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FAQs

At Oil and Gas Corrosion we help the Oil and Gas industry finding answers to some of their most difficult questions. We have created this section hoping that you will find answers to some of the most common questions in the following areas:

  • H2S
  • ANSI/NACE MR0175 / ISO 15156
  • Corrosion in offshore industry
  • Downhole corrosion
  • Materials Selection

If you require technical support in metallurgy, corrosion, or welding; or if you need assistance meeting the requirements of ANSI/NACE MR0175/ISO 15156 then contact our team, we are here to help you.

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  • 1. Who is in charge of NACE MR0175 / ISO 15156?
     

    The document is maintained by a maintenance panel, the role of the Maintenance Panel is solely to ensure that NACE MR0175/ ISO 15156 is clear in its stated requirements and is kept up-to-date. You can find more information in the ISO website www.iso.org/iso15156maintenance

    Since 2007, NACE MR0175 / ISO 15156 is a document updated by an ISO dedicated Maintenance Agency that has established 3 groups of experts for the process of reviewing and updating this standard. The first group is the Maintenance Panel; formed by 15 experts, the Maintenance Panel reviews the document and proposes any changes. Proposed changes are reviewed and balloted by the TG299 Oversight Committee (second group). If approved, changes are confirmed by ISO TC67 WG7 (third group) and incorporated into the document for publication in the next revision. Each country then incorporates the document as a national standard through their national committees and standardization bodies. Information regarding this process can be found in the ISO website.

    The role of the Maintenance Panel is solely to ensure that NACE MR0175/ ISO 15156 is clear in its stated requirements and is kept up-to-date. You can find more information in the ISO website www.iso.org/iso15156maintenance

    Some of the questions in this section are inquiries and clarifications submitted to the maintenance panel. References are used where appropriate.

    We are here to help you, if you need help with interpretation and implementation of NACE MR0175 you can contact us. 

     

    With a wealth of experience in the oil and gas industry, we provide independent materials and corrosion consultancy to help companies reduce risk, save money and apply best practice in their oil and gas businesses.

    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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  • 2. Is 22HRC the only requirement to meet NACE MR0175?
     

    Is 22HRC the only requirement to meet NACE MR0175? from Ivan Gutierrez on Vimeo.

    Ivan Gutierrez clarifies is 22HRC is the only requirement to meet NACE MR0175

    Question: Is 22HRC the only requirement to meet NACE MR0175?

    Answer:

    No, a maximum hardness of 22 HRC is one of the requirements for some carbon steel and low alloy steels and it is not the only requirement. In this video, Ivan Gutierrez, Managing Director of Oil & Gas Corrosion discusses what other requirements need to be fulfilled to meet NACE MR0175.

    Carbon and low alloy steels must meet requirements of chemical composition, heat treatment, and HIC resistance to fulfil the NACE MR0175 requirements. The risk of HIC and other cracking mechanisms needs to assessed.

    Stainless steels and other Corrosion Resistant Alloys (CRAs) have additional requirements. Furthermore, for each type of CRA, different applications may have different requirements, e.g. downhole components requirements may be different to valves and pipeline material.

    Visit our Frequently Asked Questions sections to access more information on NACE MR0175.

    If you have to supply material to NACE MR0175, or if you need to specify NACE MR0175 as a project requirement, talk to our corrosion consultants and oilfield metallurgists. We have the Technical Authority to help you comply with NACE MR0175 / ISO 15156.

    Talk to our team today!

     

    With a wealth of experience in the oil and gas industry, we provide independent materials and corrosion consultancy to help companies reduce risk, save money and apply best practice in their oil and gas businesses.

    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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  • 3. What is the difference between pressure containing and pressure retaining parts? and how does NACE MR0175 apply?
     

    ANSI / NACE MR0175/ISO 15156 defines a pressure-containing part as follows:

    part whose failure to function as intended results in a release of retained fluid to the atmosphere

    EXAMPLES Valve bodies, bonnets and stems.

    NACE MR0175 does not provide an exhaustive list of "pressure containing parts". Some users require a definite definition between pressure-containing parts and pressure-retaining parts. Regardless of a design code definition of pressure containing or pressure retaining parts,  NACE MR0175, in part 1 Clause 5, states that the equipment user shall determine whether or not the service conditions are such that NACE MR0175 applies and to ensure that any material specified for use is satisfactory in the service environment. This means that the equipment user must identify which parts require compliance with NACE MR0175 (including pressure containing and pressure retaining parts).

    At Oil & Gas Corrosion, we get this question all the time “What is the difference between pressure-containing and pressure-retaining parts?”. The answer to this will depend on the applicable regulatory framework and design codes, nevertheless we have put together a few examples of how these parts are defined according to relevant references.

    ASME PTC 23
    • Pressure Containing Member: A component which is exposed to and contains pressure
    • Pressure Retaining Member: A component which holds one or more pressure containing members together but is not exposed to the pressure.
    Various documents from API such API 16A, API 16AR, API Std 674 These API documents follow a very similar approach:

    • A pressure-containing part is exposed to the fluid exerting the pressure and failure to function as intended results in release of fluids. These parts act as a barrier between the fluid and the environment.
    • A pressure-retaining part is not exposed to the fluid exerting the pressure, it is stressed due to the effects of a differential pressure, failure to function as intended results in release of fluids.
    API 6X
    • pressure-containing: component whose failure to function as intended results in a release of retained fluid to the atmosphere.
    • pressure-retaining is not included in this document.
    Pressure Equipment Directive (PED) 2014/68/EU (formerly97/23/EC)
    • PED 2014/68/EU does not address pressure containing or retaining parts, the term used is “pressure-bearing parts”. The main pressure-bearing parts are the parts, which constitute the envelope under pressure, and the parts which are essential for the integrity of the equipment.

    These are just some examples of how pressure-containing and pressure retaining parts are defined in different codes. When pressure equipment is exposed to sour service conditions, the equipment user must define which parts need to comply with the relevant materials requirements such as NACE MR0175 or NACE MR0103. There is no general rule that covers all possible scenarios and as such, a materials engineer must review which pressure-containing and pressure-retaining parts have to comply with NACE MR0175.

    At Oil & Gas Corrosion we help manufacturers and users to carry out a material selection review for their design and to identify the parts that need to meet the requirements of NACE MR0175 / ISO 15156.

    We can help you review and document that your design complies with NACE MR0175 / ISO 15156 and the relevant regulatory requirements such as ASME VIII, PED 2014/68/EU, etc.

     

    Talk to our team today!

     

    With a wealth of experience in the oil and gas industry, we provide independent materials and corrosion consultancy to help companies reduce risk, save money and apply best practice in their oil and gas businesses.

    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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    In 2003 an inquiry was sent to the NACE MR0175 Maintenance Panel:

    Question: Definition of pressure-containing parts: “Those parts whose failure to function as intended would result in a release of retained fluid to the atmosphere. Examples are valve bodies, bonnets, and stems.” Are stems always defined as pressure-containing parts, regardless of features that by design keep the stem intact? Example #1: Internal entry stems for ball valves that have a shoulder that rests against the body around the stem bore. Example #2: Shafts for butterfly valves that have a retaining ring holding the shaft inside the valve.

    Answer:

    The NACE MR0175/ISO 15156 maintenance panel cannot interpret design issues.

    This question is in relation to NACE MR0175/ISO 15156-2 Clause 3.14

    Reference: ISO 15156 Maintenance Panel Inquiry #2003-12 Q2.

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  • 4. In NACE MR0175, Is a welding consumable with a nickel content of 1.03% acceptable ?
     

    Question: Is a welding consumable with a nickel content of 1.03% acceptable or is 1.00% the maximum allowed?

    Answer:

    For carbon and low-alloy steels, 1% nickel has been set to be the maximum to avoid SSC. However, a value above 1% could be used if it is qualified as stated in A.2.1.4. It is not the role of the Maintenance Panel to give an opinion on a specific metallurgical issue.

    This question is in relation to NACE MR0175/ISO 15156-2 Clause 5.3.1.4

    Reference: ISO 15156 Maintenance Panel Inquiry #2009-20

     

    With a wealth of experience in the oil and gas industry, we provide independent materials and corrosion consultancy to help companies reduce risk, save money and apply best practice in their oil and gas businesses.

    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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  • 5. In NACE MR0175, does “Hardness of parent metals” apply to machined forgings just to weldment parent metals?
     

    Question: Do NACE MR0175/ISO 15156-2, 7.3.2 “Parent metals” and NACE MR0175/ISO 15156-3, 6.2.1 “Hardness of parent metals” apply to machined forgings or are they meant to be applied to weldment parent metals only?

    Answer:

    The requirements listed in NACE MR0175/ISO 15156-2 Section 7.3.2 apply to the parent materials applicable to part 2; carbon and low alloy steels and cast irons. The parent materials include forgings. See also sections A.2.1.2 and A.2.1.3 of Annex A for additional requirements. The requirements listed in NACE MR0175/ISO 15156-3 Section 6.2.1 apply to parent materials applicable to part 2; CRAs and other alloys. The parent materials include forgings

    This question is in relation to NACE MR0175/ISO 15156-3 Clause 6.2.1

    Reference: ISO 15156 Maintenance Panel Inquiry #2014-03

     

    With a wealth of experience in the oil and gas industry, we provide independent materials and corrosion consultancy to help companies reduce risk, save money and apply best practice in their oil and gas businesses.

    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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  • 6. Seal welding of vent holes on saddle plates welded to pipe, do they need to comply with NACE MR0175?
     

    Talk to our team for answers on seal welding of vent holes. 

    Question:

    Seal welding of vent holes on saddle plates welded to pipe. We have provided vent holes on saddle plates in accordance with ASME B31.3. We have used these saddle plates at support locations as a protective shield to pipe. Now we would like to close the vent hole by seal welding after completion of saddle welding with pipe and carrying out PWHT. Permanent closing of vent hole is required to avoid corrosion in offshore conditions. Service is crude oil with H2S, i.e., NACE MR0175/ISO 15156 is applicable. Kindly advise us about the acceptance of seal welding for these service conditions.

    Answer:

    The ISO 15156 Maintenance Panel cannot provide guidance on the acceptability of seal welding in this application.
    It is the responsibility of the equipment user to decide whether NACE MR0175/ISO 15156-2 is applicable to these seal welds. The applicability of this standard is described in Clause 1, Scope.
    If this standard is considered applicable then the seal welds must comply with the requirements of NACE MR0175/ISO 15156-2, 7.3.3 or NACE MR0175/ISO 15156-3, 6.2.2.

    This question is in relation to NACE MR0175/ISO 15156-2 Clause 7.3.3

    Reference: ISO 15156 Maintenance Panel Inquiry #2005-21

     

    With a wealth of experience in the oil and gas industry, we provide independent materials and corrosion consultancy to help companies reduce risk, save money and apply best practice in their oil and gas businesses.

    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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  • 7. Is it acceptable to use HV 500g (microhardness) testing for NACE applications for WPS qualification?
     

    Question: Is it acceptable to use HV 500g (microhardness) testing for NACE applications for WPS qualification? I understand that Paragraph 7.3.3.2 of NACE MR0175/ISO 15156 Part 2 says that hardness testing shall normally be carried out using HV 10kg or HV 5kg, which is our usual practice. FYI, the hardness testing was done with HV 500g on CSA Z245.1 Grade 359 pipe material.

    Answer:

    Yes, subject to the agreement of the equipment user. Please see NACE MR0175/ISO 15156-2, Para. 7.3.3.2.

    This question is in relation to NACE MR0175/ISO 15156-2 Clause 7.3.3.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2006-08

     

    With a wealth of experience in the oil and gas industry, we provide independent materials and corrosion consultancy to help companies reduce risk, save money and apply best practice in their oil and gas businesses.

    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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  • 8. In NACE MR0175, what does "as close as possible to, but no more than 1mm from, the fusion boundary" mean?
     

    Question:

    Per 7.3.3.3 Using the Vickers or Rockwell 15N measurement methods, hardness impressions 2, 6, and 10 should be entirely within the heat-affected zone and located as close as possible to, but no more than 1mm from, the fusion boundary between the weld overlay and HAZ." Is a correct interpretation that when welding dissimilar metals such as corrosion resistant overlays on low alloy steels, the phrase, "as close as possible to, but no more than 1mm from, the fusion boundary" means that the indentation should be no less than 3x the mean diagonal length of the indentation from the fusion boundary as is required for adjacent indentations in ISO 6507-1:1998? Note: ISO 6507-1:1998 is referenced by NACE/ISO 15156-2 in the first paragraph of Section 7.3.3.2 (Hardness testing methods for welding procedure qualification).

    Answer:

    The ISO 15156 Maintenance Panel cannot provide an interpretation of the ISO 6507-1:1998 in relation to the minimum distance of hardness indentations from the boundary between the base metal and the overlay weld.
    As stated in ISO 15156-2, 7.3.3.2 and ISO 15156-3, 6.2.2.2.2 hardness measurements can also be carried out using a smaller indentation load, for example HV5 rather than HV10, and in many cases this will allow compliance with the requirements of ISO 15156-2, Fig. 6.

    It is important to recognize that there will be a gradient in HAZ hardness in any case, and thus measurements too far from the fusion boundary could be un-conservative.

    In all cases it is the task of the equipment user (and hence the supplier) to ensure that the hardness values measured are the most representative possible of the cracking resistance of the welded material in any sour service it is expected to experience.

    This question is in relation to NACE MR0175/ISO 15156-2 Clause 7.3.3.3

    Reference: ISO 15156 Maintenance Panel Inquiry #2006-01Q2

     

    With a wealth of experience in the oil and gas industry, we provide independent materials and corrosion consultancy to help companies reduce risk, save money and apply best practice in their oil and gas businesses.

    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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  • 9. If sulphur and phosphorous are controlled, is HIC testing necessary as per NACE MR0175?
     

    ANSI/NACE MR0175/ISO 15156 states that the risk Hydrogen Induced Cracking (HIC) needs to be evaluated, and testing as per NACE TM0284 should be considered to demonstrate a specific materials are HIC resistant. Oil & Gas Corrosion can help you decide if HIC testing is required. Talk to our team today.

    Question: We are trying to interpret the NACE/ISO requirements for pressure vessel plate material. The NACE/ISO standard leaves the option of HIC testing with the client, as it appears. In accordance with the standard, the condition in which the HIC testing becomes mandatory should be based on some criteria other than H2S partial pressure. We would appreciate it if you can guide in giving the other conditions if sulfur and phosphorous content are controlled in accordance with NACE/ISO. Does HIC become mandatory due to non-uniformity of sulfur and phosphorous in the material due to steelmaking process even if the limit of these elements are maintained? Are there other reasons such as chloride environment?

    Answer:

    The statements in ISO 15156-2, 8 "Evaluation of carbon and low-alloy steels for their resistance to HIC/SWC" are based on the extensive experience of the experts who drew up the requirements of the standard.

    They serve as a warning to the equipment user that damage to products from some flat-rolled carbon steel types due to HIC has been common and the risk of attack must be considered when selecting such materials for sour service. (See ISO 15156-1, 3.19 for definition of sour service in this context.) They also provide some indications of the types of flat-rolled carbon steel likely to give satisfactory resistance to HIC.

    The overall aim of ISO 15156-2, Clause 8, is to ensure that materials that give satisfactory HIC performance in sour service can be selected. It is not the intention of this Clause to provide detailed information that can lead to the qualification, without testing, of HIC-resistant steels.

    If, in accordance with NACE MR0175/ISO 15156:2, Clause A.2.2.2, Paragraph 3, the HIC resistance of flat-rolled plate is uncertain then the equipment user can elect to carry out HIC testing, possibly for use in an application-specific environment. Testing in accordance with Annex B.5 is proposed as a means of qualifying the material to ISO 15156-2.

    Testing is not necessary if the equipment user can document that he has evaluated the risk of HIC failure of his equipment and considers the risk acceptable.

    This question is in relation to NACE MR0175/ISO 15156-2 Clause 8

    Reference: ISO 15156 Maintenance Panel Inquiry #2005-04

    The team at Oil and Gas Corrosion Ltd has prepared checklists that will help you make sure your material complies with NACE MR0175, visit the live and fully functional checklist for:

    ASTM A516 Gr 70 NACE MR0175

    We can also help you quantify the risk of HIC and determine the requirements to meet NACE MR0175.

    UPDATE 2018-06-04: A recent Technical Circular brings relevant updates on NACE MR0175 regarding the HIC testing acceptance criteria: https://oilandgascorrosion.com/nace-mr0175-iso-15156-technical-circulars-for-part-2-and-3-published-2018-06-01/

    We are here to help you, talk to our team today!

     

    With a wealth of experience in the oil and gas industry, we provide independent materials and corrosion consultancy to help companies reduce risk, save money and apply best practice in their oil and gas businesses.

    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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  • 10. What is NACE MR0175 acceptance criteria for HIC / NACE TM0284?
     

    ANSI/NACE MR0175/ISO 15156 requires carbon steels and low alloy steels to be HIC resistant. One way to confirm HIC resistance is by testing as per NACE TM0284, the acceptance criteria is as per NACE MR0175.

    If you require additional support to confirm HIC resistance of a material talk to our team, we are Corrosion Consultants in Oil & Gas and we are here to help you.

    Question: It appears that ISO 15156-2 is ambiguous in defining the acceptance criteria for HIC testing. Section B.5 and Table B.3 refer to NACE TM0284. This TM prescribes CLR, CTR, and CSR results to be reported for each of the three sections taken from a specimen and also as the average per specimen.

    Q1. Could you please confirm that the intention of Section B.5 and Table B.3 is that the requirements of NACE TM0284 for the evaluation of test specimens should be followed and that CLR, CTR, and CSR should be calculated and reported for each section and the average for each test specimen. Table B.3 does not specify if the criteria apply to the single section numbers or to the averages per specimen or to the averages over a series of specimens. The last of these was suggested recently to us, for qualification purposes, by a materials manufacturer. ISO 3183-3 (the successor to API 5L) uses the same CLR, CTR, and CSR values as criteria as ISO 15156 but in addition it mentions that averages per specimen should be measured against the acceptance criteria (not single section numbers). I think it is common practice to apply this approach. If one decides that the acceptance criteria are to be applied to single sections, I do not believe that using, in addition, the same criteria for the average per specimen yields any useful additional information (because it is less restrictive), but it does no harm either. If, however, one decides that the acceptance criteria are to be applied only to the average per specimen, I am of the opinion that an additional condition should be imposed for single section results or for single crack lengths, for instance, no single crack length should exceed 5 mm, as part of the overall acceptance requirements.

    Q2. Are the acceptance criteria intended to apply to the test results of both single section and the average per specimen?

    Q3. Is the intention that, in coming to a qualification the CLR, CTR, and CSR values be calculated by averaging the results for a series of specimens?

    Q4. If they are intended to apply to only the average per specimen, what additional requirements should be placed on the results of single section results?

    Answer:

    A1. Yes.
    A2. The referenced standard, NACE TM0284, Paragraph 8.4, requires the (calculation and) reporting of test results for each of three sections and the average for each test specimen. The application of the acceptance criteria to single section and/or the average for a specimen is subject to agreement between equipment user and the manufacturer.
    A3. See Answer A.2 above, the referenced standard NACE TM0284 makes no mention of calculating results by averaging the results for a series of test specimens.
    A4. The Maintenance Panel is unable to comment on issues that would involve an extension of the requirements of the standard. Any materials purchaser is free to add requirements beyond those required or made optional by the standard. Any amendment proposal to extend the requirements for single section test results must be submitted in accordance with the requirements outlined in:-
    01. Introduction to ISO 15156 maintenance activities (Annex C) of the web site
    www.iso.org/iso15156maintenance.

    This question is in relation to NACE MR0175/ISO 15156-2 Clause 8

    Reference: ISO 15156 Maintenance Panel Inquiry #2006-11

    The team at Oil and Gas Corrosion Ltd has prepared checklists that will help you make sure your material complies with NACE MR0175, visit the live and fully functional checklist for:

    ASTM A516 Gr 70 NACE MR0175

    A new revision of NACE TM0284 was issued in 2016; make sure you read our article on the main changes of NACE TM0284 2016: https://oilandgascorrosion.com/tm0284-2016/

    UPDATE 2018-06-04: A recent Technical Circular brings relevant updates on NACE MR0175 regarding the HIC testing acceptance criteria: https://oilandgascorrosion.com/nace-mr0175-iso-15156-technical-circulars-for-part-2-and-3-published-2018-06-01/

    We are here to help you, talk to our team today!

     

    With a wealth of experience in the oil and gas industry, we provide independent materials and corrosion consultancy to help companies reduce risk, save money and apply best practice in their oil and gas businesses.

    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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    UK: +44(0)1144000850

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  • 11. Does NACE MR0175 require PWHT of overlay weld inconel 625?
     

    Question:We have weld overlays (Inconel 625 filler metal with SAW process) applied to low-alloy ferritic steel valves (ASME/ASTM A 352 Gr LCC). The steel valve is used on wet gas wellhead production platform with operating temperatures at 93°C, operating pressure of 145 bar with vapor fraction of H2S (177 kg-mol/h) and CO2 (877 kg-mol/h). Hardness tests were performed on the as-welded condition. The results achieved were well below the 250 HV criteria of Table A.1 of NACE MR0175/ISO 15156-2. Since the hardness results complied with the requirements of Table A.1 of NACE MR0175/ISO 15156-2, we believe and understand that the valve does not require postweld heat treatment after the weld overlay. Having met the hardness criteria after overlay we believe that we met the requirements of the following paragraphs of NACE MR0175/ISO 15156-2: -Paragraph A.2.1.5 and -Paragraph A.2.1.4 Question: Is our interpretation of Paragraphs A.2.1.5 and A.2.1.4 of NACE MR0175/ISO 15156-2 correct based on the above-stated specific application and conditions and that the valves overlayed with Inconel 625 consumables do not require postweld heat treatment?

    Answer:

    Paragraph A.2.1.4 states (in the third sentence):
    “As welded carbon steels, carbon manganese steels, and low-alloy steels that comply with the hardness requirements of Table A.1 do not require postweld heat treatment.” Paragraph A.2.1.5 states: “Overlays applied by thermal processes such as welding . . . are acceptable if they comply with one of the following: (a) The heat-treated condition of the substrate is unchanged, i.e., it does not exceed the lower critical temperature during application of the overlay. (b) The maximum hardness and final heat-treated condition of the base metal substrate comply with A.2.1.2 and, in the case of welded overlays, A.2.1.4.
    Therefore, your interpretation is correct. Provided your weld procedure qualification complies with the hardness requirements in A.2.1.4 and A.2.1.5, no postweld heat treatment is required.

    This question is in relation to NACE MR0175/ISO 15156-2 Annex A.2.1.4 and A.2.1.5

    Reference: ISO 15156 Maintenance Panel Inquiry #2004-11

    UPDATE 2018-06-04: A recent Technical Circular brings relevant updates on NACE MR0175 and 625 weld overlays: https://oilandgascorrosion.com/nace-mr0175-iso-15156-technical-circulars-for-part-2-and-3-published-2018-06-01/

    We are here to help you, talk to our team today!

     

    With a wealth of experience in the oil and gas industry, we provide independent materials and corrosion consultancy to help companies reduce risk, save money and apply best practice in their oil and gas businesses.

    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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  • 12. What are the NACE MR0175 requirements for risers (choke, kill and booster) lines?
     

    Question:

    We have a request for interpretation of item A.2.2.3.3 of ISO 15156-2. It states that “tubulars and tubular components made of Cr-Mo low alloy steels (UNS G41XX0, formerly AISI 41XX, and modifications), if quenched and tempered in the tubular form, are acceptable if the hardness does not exceed 26 HRC. These products should be qualified by SSC testing in accordance with B.1 using the UT test.” We use AISI 4130 tubes in the quenched and tempered condition for drilling riser P-lines (choke, kill and booster lines) and have at present a hardness limit of HRC 22. The relaxation of above hardness requirement to HRC 26 would be helpful in production of the pipes as well as weldments.

    Answer:

    Paragraph A.2.2.3.3 of ISO 15156-2 is applicable to downhole casing, tubing, and tubular components used in region 3 of the diagram in Paragraph 7.2. Materials for P-lines in drilling risers are not included in Paragraph A.2.2.3.3. Materials for P-lines used in Region 3 are hardness limited to HRC 22. The point you raise concerning Inquiry 2005-23 is valid since testing according to Table B.1 in Annex B is one of the accepted qualification methods. Testing can be used to qualify any material/application (including 4130/P-lines in drilling risers) provided it is performed according to ISO 15156 requirements.

    This question is in relation to NACE MR0175/ISO 15156-2 Annex A.2.2.2 and A.2.2.3

    Reference: ISO 15156 Maintenance Panel Inquiry #2010-04

     

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  • 13. What does the MR0175 define as a shear blade?
     

    Question:

    What does the MR0175 define as a shear blade?

    Answer:

    No. NACE MR0175 does not define the term "shear blades".

    This question is in relation to NACE MR0175/ISO 15156-2 Annex A.2.3.2.1

    Reference: ISO 15156 Maintenance Panel Inquiry #2015-05rev1 Q1

    Question: MR0175 states “The suitability of shear blades that do not comply with this annex is the responsibility of the equipment user”. Does the equipment user taking responsibility for the suitability of the shear blades make the shear blades compliant with MR0175?

    Answer:

    No. Blowout preventer shear blades are included in the list of equipment that has permitted exclusions in Part 2 Table 1 and Part 3 Table 1. In Part 2 Section A.2.3.2.1, the cautionary note is there to alert the end user that the shear blades can be susceptible to SSC.

    This question is in relation to NACE MR0175/ISO 15156-2 Annex A.2.3.2.1

    Reference: ISO 15156 Maintenance Panel Inquiry #2015-05rev1 Q2

    At Oil & Gas Corrosion we can help you with interpretation and implementation of NACE MR0175.

     

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  • 14. The NACE MR0175 requirements for shear rams
     

    Question: The title of Paragraph A.2.3.2.2 in NACE MR0175/ISO 15156-2 is “Shear rams.” This section allows the use of rams made from quenched and tempered, Cr-Mo, low-alloy steels up to a maximum hardness of 26 HRC provided the composition and heat treatment are carefully controlled and supporting SSC testing is performed. The text of this section does not limit these provisions to just shear rams; however, the section title would imply that only shear rams are covered by its provisions. This apparent shear ram restriction was not in previous revisions of the standard. It is important to ram manufacturers as well as end users that all Cr-Mo, low-alloy steel rams, not just shear rams, be allowed up to 26 HRC to ensure maximum hang-off capacity and for anti-extrusion purposes. Do the provisions of A.2.3.2.2 apply only to shear rams or can they be applied to other types of rams as well?

    Answer:

    The requirements for Cr-Mo, low-alloy steel rams in A.2.3.2.2 in NACE MR0175/ISO 15156-2 are not intended to be restricted to shear rams only, but may be applied to other types of rams as well. This is consistent with all previous revisions of MR0175.

    This question is in relation to NACE MR0175/ISO 15156-2 Annex A.2.3.2.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2004-16

    At Oil & Gas Corrosion we can help you understand and define the NACE MR0175 requirements. 

     

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  • 15. NACE Standard MR0175 accepts ductile iron to ASTM A 395. Can we use ASTM A 536 Grade 60/40/18?
     

    Question: I have a query regarding material suitability on a recent enquiry to supply a nodular iron screw compressor. NACE Standard MR0175 accepts ferritic ductile iron to ASTM A 395. My question is if our existing in-house standard of ASTM A 536 Grade 60/40/18 will comply as a direct alternative. On the face of it tensile strength, elongation are similar at 415N/mm2 and 18%!

    Answer:

    The ISO Maintenance Panel cannot advise on materials selection issues. The role of the Maintenance Panel is solely to ensure that NACE MR0175/ISO 15156 (the current edition of NACE MR0175) is clear in its stated requirements and is kept up-to-date.
    Should you wish, the procedure to propose an amendment to the standard to include ASTM A 536 Grade 60/40/18 is described in
    "01. Introduction to ISO 15156 Maintenance Activities" on the Web site
    www.iso.org/iso15156maintenance.

    This question is in relation to NACE MR0175/ISO 15156-2 Annex A.2.4.3

    Reference: ISO 15156 Maintenance Panel Inquiry #2005-27

    We can help you verify materials substitution and compliance with NACE MR0175.

     

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  • 16. The OTI 95 635 reference in NACE MR0175
     

    Question:

    During the last ISO/TC 67 plenary meeting on 2012-09-19/20 in Rio the UK delegation had a request to the ISO 15156 MP regarding ISO 15156-2. Following resolution was taken and is in the minutes: Resolution 2012/08 (Rio de Janeiro, 2012) The British delegation, noted that ISO 15156-2 includes a reference to the British publication OTI 95 635, Testing method to determine the susceptibility to cracking of line pipe steels in sour service. This publication is about 20 years old and the British delegation would request the ISO 15156 Maintenance Panel under WG 7 to review whether this British publication is still needed and if so to develop an international standard on this subject, so that the British publication could be withdrawn. Additional information: • OTI 95 635 can be found via: https://www.hse.gov.uk/research/otipdf/oti95635.pdf • The document is mentioned only in ISO 15156-2: B.4.3 Full pipe ring tests Full pipe ring tests may be used. The document HSE OTI-95-635 describes a test and acceptance criteria. NOTE Residual stress has been shown to play an important role in the initiation of SOHIC and SZC. It is sometimes considered that such stresses in field situations are better represented in large-scale specimens. and in Bibliography [27] HSE OTI-95-635 7), A test method to determine the susceptibility to cracking of line pipe steels in sour service 7) UK Health and Safety Executive, HSE Books, PO Box 1999, Sudbury, Suffolk CO10 2WA, UK [ISBN 0-7176-1216-3].

    Answer:

    Developing a new international standard is outside the scope of the Maintenance Panel. The British publication is still assumed to be technically relevant, but the OTI 95 635 reference will be removed if the publication is withdrawn.

    This question is in relation to NACE MR0175/ISO 15156-2 Annex B.4.3

    Reference: ISO 15156 Maintenance Panel Inquiry #2012-10.

     

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  • 17. Non-ideal gas behavoir, HPHT wells and NACE MR0175 - partial pressure of H2S
     

    Question: NACE MR0175/ISO 15156, Part 2, Annex C, Section C.1 states that "The partial pressure of H2S may be calculated by multiplying the system total pressure by the mol fraction of H2S in the gas." Does the word "may" permit other methods, such as incorporating the effects of non-ideal gas behavior, to calculate partial pressure for determining material selection?

    Answer:

    Yes. Please note: Annex C as a whole is "informative" rather than "normative" and is therefore not mandatory.

    This question is in relation to NACE MR0175/ISO 15156-2 Annex C

    Reference: ISO 15156 Maintenance Panel Inquiry #2004-08

    At Oil & Gas Corrosion we see many enquiries related to the partial pressure of H2S. We have the expertise to support you selecting materials where ideal gas behaviour deviated such as High Pressure and High Temperature wells (HPHT). We do this by evaluating the production conditions (pressure, temperature, produced water etc) and evaluating the risks and consequences. Let us help you with the materials selection and partial pressure calculations.

     

     

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    The partial pressure of H2S (ppH2S ) is used throughout ANSI/NACE MR0175/ISO 15156 to set the production environment limits for carbon steels, low alloy steels and corrosion resistant alloys. However, NACE MR0175 does not specify if the user should consider operation pressure, design pressure or an intermediate value. So, what is NACE MR0175 intent when it comes to H2S partial pressure? operating or design pressure to be used in the calculations? Here, Oil & Gas Corrosion addresses these questions.

    First, we have to define the partial pressure of H2S (ppH2S ) which is calculated as:

                     ppH2S = system total absolute pressure x mol fraction of H2S present

    Is the system total absolute pressure the design or the operating pressure? This is one of the most  frequently asked questions and this video clarifies if design or operating pressure should be used.

    partial pressure of H2S, design or operating conditions? from Ivan Gutierrez on Vimeo.

     

    At Oil & Gas Corrosion we help clients to determine the partial pressure of H2S. We have the expertise to help you decide if you should use the operating or design pressure. We do this by evaluating the production conditions (pressure, temperature, produced water etc.), the design and evaluating the risks and consequences. We are here to help you with sour service materials selection and partial pressure calculations.

    Talk to our team to today!

     

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    This video makes reference to an inquiry sent to the NACE MR0175 maintenance panel. The inquiry is below:

    QUESTION: What is NACE’s intent when it comes to H2S partial pressure? i.e., when calculating the H2S partial pressure per Annex C.1 and C.2 in NACE MR0175/ISO 15156-2, should the operating or design pressure be used in the calculations? I believe operating pressure should be used. Could you please confirm?

    ANSWER:

    15156-1 Para 6.1 states that the user shall define the service conditions including unintended exposures (e.g., resulting from failure of primary containment). These service conditions become the basis for calculating H2S partial pressure. It is up to the user to decide whether to use operating or design pressure for partial pressure calculations.

    Reference: ISO 15156 MP Inquiry #2009-21 (NACE MR0175 Part 2 Annex C)

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  • 18. NACE MR0175, austenitic stainless steels, Table A.2 and the technical circulars.
     

    We have a full article on the latest revision of NACE MR0175 2015, make sure you read the full article as it addresses austenitic stainles steels.

    Question: NACE MR0175/ISO 15156-3: 2009(E) Table A2 & NACE MR0175/ISO 15156-3: 2009/Cir.2:2013(E), Table A2 As long as the partial pressure of H2S is below 15 psi and Flowing medium temperature is below 140 DEG F Any combinations of chloride concentration and in situ pH occurring in production environments are acceptable and materials as suggested under clause A2 “Austenitic stainless steels” can be selected.

    Answer:

    As long as your definition of “Flowing medium temperature” is “exposure temperature” your interpretation is correct. Note that these materials shall be of type described in A.2, shall be in the solution-annealed and quenched, or annealed and thermally-stabilized heat-treatment condition, be free of cold work intended to enhance their mechanical properties, and have a maximum hardness of 22 HRC.

    This question is in relation to NACE MR0175/ISO 15156-3 Table A.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2015-02 Q2 & Q3

    alloy select is the only web-based software for materials selection of oil and gas assets and has been developed by the team of experts at Oil & Gas Corrosion. alloy-select can help you confirm austenitic stainless steels are suitable for production environments and verify compliance with NACE MR0175 and other industry standards. To learn more about alloy-select visit alloyselect.com

    At Oil & Gas Corrosion we see many enquiries related to the 316, 316L and other austenitic stainless steels. Let us help you find the optimal solution for you.

     

    With a wealth of experience in the oil and gas industry, we provide independent materials and corrosion consultancy to help companies reduce risk, save money and apply best practice in their oil and gas businesses.

    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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  • 19. NACE MR0175 and orbital welding of austenitic stainless steels
     

    Question:

    My stainless steel sheet material qualifies to Section A.2. I am forming this sheet into tubes and (longitudinally) welding the formed tube without filler metals using an automatic arc welding process (ASTM 249/ASTM 269). After welding the tube is fully annealed per ASTM. My hardness values are all below 22 HRC as required. A. Is my welded and annealed tubing bound to the welding requirements of A.2.3 and 6.2.2? B. After annealing, if I now butt weld two ends of the tubing above using the orbital weld (no filler metal) process (no additional anneal), am I now bound to A.2.3 and 6.2.2?

    Answer:

    A. Yes, this is still a weld even if it was made without filler materials.

    B. Yes.

    This question is in relation to NACE MR0175/ISO 15156-3 Annex A.2.3

    Reference: ISO 15156 Maintenance Panel Inquiry #2004-19 Q2

     

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  • 20. ISO 13680 and NACE MR0175 have different hardness limits for solid solution nickel based alloys, which one to follow?
     

    Question: NACE MR0175/ISO 15156 Table A.14 (Environmental and materials limits for annealed and cold worked, solid-solution nickel-based alloys used as any equipment or components) at the bottom indicates "The maximum hardness value for these alloys in these applications shall be 40 HRC." 2. ISO 13680 Table C.27 (Example for PSL-2 product mechanical properties at room temperature) indicates Mean Hardness Number of 33 or 35 HRC depending on the grade (Category 3). These are vastly different values--I appreciate your thoughts.

    Answer:

    The MP can only answer about NACE MR0175/ISO 15156 Standard. The maximum hardness values correspond to the maximum hardness values of the tested materials. The MP cannot comment on hardness values from other ISO standards like ISO 13680.

    This question is in relation to NACE MR0175/ISO 15156-3 A.14

    Reference: ISO 15156 Maintenance Panel Inquiry #2010-10

    Talk to us to resolve your nickel alloys inquiries.

     

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  • 21. What is the difference between NACE MR0175 and ISO 15156?
     

    Question: What is the difference between NACE MR0175 and ISO 15156?

    Answer:

    There is no technical difference. The documents are identical, NACE MR0175 and ISO 15156 is the same document  and it is written and maintained by the same committee. ISO 15156 is the document number adopted by ISO while NACE MR0175 is the document number used by NACE, ANSI NACE MR0175 is the official document number within the US. In the UK the document is BS EN ISO 15156.

    In terms of the technical requirements and the information presented by this document, there is no difference among them, they are identical.

    At Oil & Gas Corrosion we can help you implement the requirements of ANSI/NACE MR0175 / ISO 15156. Talk to our team today!

     

    With a wealth of experience in the oil and gas industry, we provide independent materials and corrosion consultancy to help companies reduce risk, save money and apply best practice in their oil and gas businesses.

    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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  • 22. If a product doesn’t meet NACE MR0175, how long will it take before it fails?
     

     

    At Oil & Gas Corrosion we frequently receive this question "If a product doesn’t meet NACE MR0175, how long will it take before it fails?", our answer to this is always the same.

    We need to assume that it will be an immediate catastrophic failure. Furthermore, you must remember that H2S is fatal in very low concentrations, therefore an uncontrolled release can lead to sudden death of anyone in range. Read more about the dangers of H2S in this article

    If you allow material and equipment that does not meet NACE MR0175 / ISO 15156 to be in contact with H2S, you could be breaking the law according to the United States Code of Federal Regulations, in the United Kingdom the Health and Safety Executive regulations and local legislation in other countries. 

     

    With a wealth of experience in the oil and gas industry, we provide independent materials and corrosion consultancy to help companies reduce risk, save money and apply best practice in their oil and gas businesses.

    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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  • 23. Is there a NACE office available in Italy or in other European countries?
     

    Question:

    Is a NACE office available in Italy or in other European countries?

    All inquiries should be transmitted to the ISO Maintenance NACE Headquarters in Houston, Texas (Maintenance.Panel@nace.org). The Maintenance Panel has an international membership. Details of its current membership can be obtained from the above address.

    This question is in relation to NACE MR0175/ISO 15156

    Reference: ISO 15156 Maintenance Panel Inquiry #2003-26 Q5

    Oil and Gas Corrosion comment:

    NACE International, The Worldwide Corrosion Authority, serves nearly 36,000+ members in 130 countries and is recognized globally as the premier authority for corrosion control solutions. The organization offers technical training and certification programs, conferences, industry standards, reports, publications, technical journals, government relations activities and more. NACE International is headquartered in Houston, Texas, with offices in San Diego, California; Kuala Lumpur, Malaysia; Shanghai, China, Sao Paulo, Brazil and Al-Khobar, Saudi Arabia.

    Mission
    To protect people, assets and the environment from corrosion.

    Structure
    NACE International is organized into four Areas in North America and four Global Areas. NACE International has 108 sections and 33 student sections worldwide sponsor local programs to promote the exchange of corrosion information and education.

    North America Areas (U.S. & Canada)
    • Northern Area
    • Eastern Area
    • Central Area
    • Western Area

    Global Areas
    • East Asia and Pacific Area
    • West Asia and Africa Area
    • European Area
    • Latin American Area

     

    If you need support to with the interpretation and implementation of NACE MR0175 / ISO 15156 talk to our team of corrosion consultants and oilfield metallurgists.

     

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    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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  • 24. Crude oil storage, does it have to comply with NACE MR0175?
     

    Question: Crude oil storage and handling facilities operating at a total absolute pressure below 0.45 MPa. My understanding of the above paragraph is that, it includes only dead oils with no gas in equilibrium. If any gas is in equilibrium with a crude (operating less than 0.45 MPa) which contains H2S more than 0.3kPa (in the gas phase), the whole system is considered as sour. I need your advice for my understanding, if correct or not?

    Answer:

    Crude oil storage and handling facilities means that it is dead oil and H2S/CO2 have been removed. The very low residual amount is considered negligible. This is the reason why these facilities are permitted exclusions from the standard. However, it is up to the user to check that these statements are true for the considered facilities.

    This question is in relation to NACE MR0175/ISO 15156

    Reference: ISO 15156 Maintenance Panel Inquiry #2009-14

     

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  • 25. Produced water handling facilities and NACE MR0175
     

    Question: Water handling facilities (less than 0.45 MPa) I really don’t know what does it mean? It means that the possibility of corrosion is low enough to be excluded from the standard requirements? Or the consequence of the problem is minimum? Can we conclude from the above paragraph that, low pressure water handling facilities, has no gas to be released which may produce SSC or any hydrogen problems?

    Answer

    Water handling facilities have typically low service pressure, a near neutral pH and they usually contain trace amounts of H2S. Consequently their sour service severity is quite low. However, it is the responsibility of the user to check whether these assumptions are correct for the particular equipment considered.

    This question is in relation to the Scope of  NACE MR0175/ISO 15156

    Reference: ISO 15156 Maintenance Panel Inquiry #2009-15

    At Oil & Gas Corrosion we can help you select materials for water handling facilities.

     

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  • 26. Is ISO 9001/9002 required to supply NACE MR0175 equipment and material?
     

    Question:

    Some buyers in the U.S. are requesting equipment to ISO 15156, and then saying that the supplying company has to be ISO registered, i.e., has ISO 9002 in place (quality standard). As far as I know these are unrelated issues; a supplier to ISO 15156 does not have to be ISO 9002 registered. Can the Maintenance Panel confirm that ISO 9002 is not a requirement for supply to ISO 15156? Is there an equivalent U.S. standard to ISO 9002?

    Answer:

    ISO 9002 is NOT referenced in any of the ISO 15156 parts. That means ISO 9002 is not necessary to comply with ISO 15156.
    If ISO 9002 is part of a contract between two business parties, ISO 9002 becomes a requirement based on the contract, not based on ISO 15156.
    In addition, ISO 9002 has been replaced by ISO 9001: Quality management systems--Requirements.
    There are no widely accepted American equivalents to either ISO 9002 or ISO 9001.

    This question is in relation to NACE MR0175/ISO 15156

    Reference: ISO 15156 Maintenance Panel Inquiry #2009-25

     

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  • 27. Who is responsible for certification of materials and equipment to NACE MR0175? The manufacturer or the user?
     

    At Oil & Gas Corrosion we frequently receive questions about the certification of materials and equipment to NACE MR0175. This is why we prepared a short webinar on the basics of certification to NACE MR0175 and how we are helping clients to solve some of these challenges.

    Certification of materials and equipment to NACE MR0175 from Ivan Gutierrez on Vimeo.

     

    Reference: ISO 15156 Maintenance Panel Inquiry 2006-13.

    Certification can be a challenging topic and we have helped clients answer some of these questions:

    • Who is responsible for certification?

    • Our material is certified to NACE MR0175 2009 and our client needs certificates to 2015, what can we do?

    • How can a raw material (steel) manufacturer certify a material if they do not know the final application and its conditions.

    • Our material does not state "Certified to NACE MR0175", can it be used in sour service?

    At Oil & Gas Corrosion we can help you resolve this and more certification issues. Talk to our team today!

     

    With a wealth of experience in the oil and gas industry, we provide independent materials and corrosion consultancy to help companies reduce risk, save money and apply best practice in their oil and gas businesses.

    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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    Question:

    Is it the intent of NACE MR0175/ISO 15156-2 that material manufacturers state on the Material Test Certificates that material conforms to the NACE standard even though no operating criteria are known?

    Answer:

    Certification requirements are outside the scope of the standard and there are no stipulations concerning certification in NACE MR0175/ISO 15156.

    The compliance with the NACE/ISO standard of a material for use in H2S-containing environments in oil and gas can only be assessed for the material in its final product form and this may differ metallurgically from that of the material supplied by the materials manufacturer. In addition, compliance with the standard also depends on the cracking mechanisms that have to be considered.

    NACE MR0175/ISO 15156-2, Clause 9, Annex E (Informative) and NACE MR0175/ISO 15156-3, 7.2, Annex C (Informative) make some suggestions on how materials manufacturers and other suppliers might mark their materials to indicate the evaluation (testing) that they have carried out.

    This question is in relation to NACE MR0175/ISO 15156 / Certification and Compliance

     

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  • 28. What is NACE MR0175 definition of a Corrosion Resistant Alloy (CRA)?
     

    Question:

    I need your help with the definition of CRAs in Part 3 of MR0175/ISO 15156. The "corrosion-resistant alloys" is very general and does not specify whether or not the definition includes the Fe-based alloys or not. More than that, the term CRA is used together with "other alloys" making it even more confusing.

    Answer:

    NACE MR0175/ISO 15156-1, Paragraph 3.6 contains a definition of "corrosion-resistant alloy" (CRA). It reads: "alloy intended to be resistant to general and localized corrosion of oilfield environments that are corrosive to carbon steel." This is taken from EFC 17.

    "Other Alloys" are those not covered by the definitions of carbon steel or CRA. For example, copper is not considered resistant to general corrosion but is considered in NACE MR0175/ISO 15156-3.

    This question is in relation to NACE MR0175/ISO 15156-1 Clause 3

    Reference: ISO 15156 Maintenance Panel Inquiry #2004-12

     

    With a wealth of experience in the oil and gas industry, we provide independent materials and corrosion consultancy to help companies reduce risk, save money and apply best practice in their oil and gas businesses.

    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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  • 29. Are metal rupture discs outside of the scope of NACE MR0175-ISO 15156?
     

    Question: Using NACE MR0175-ISO 15156-1, Clause 5, Paragraph 9 and NACE Interpretation MP INQUIRY #2009-05 Part 1 as references. Based on the fact that most metal rupture discs are plastically deformed during manufacturing and all metal rupture discs plastically deform when they burst, are metal rupture discs outside of the scope of NACE MR0175-ISO 15156?

    Answer:

    No. Permitted exclusions are listed in ISO 15156-1 Table 1. When ISO 15156 is specified, components, including rupture discs, must comply with the materials and conditions listed in the standard or qualified in accordance with Annex B.

    This question is in relation to NACE MR0175/ISO 15156-1 Clause 5

    Reference: ISO 15156 Maintenance Panel Inquiry #2011-08

    At Oil & Gas Corrosion can help you with NACE MR0175 compliance.

     

    With a wealth of experience in the oil and gas industry, we provide independent materials and corrosion consultancy to help companies reduce risk, save money and apply best practice in their oil and gas businesses.

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  • 30. NACE MR0175 and elastic or plastic design criteria
     

     

    The question below was submitted to NACE MR0175 maintenance panel. At Oil & Gas Corrosion we can help you with materials selection to comply with NACE MR0175.

    Question: Unfortunately answer #2011-08 left my organization at a loss. This answer does not address the fact that NACE MR0175-ISO 15156-1, Clause 5 states: This part of ANSI/NACE MR0175/ISO 15156 applies to the qualification and selection of materials for equipment designed and constructed using conventional elastic design criteria. For designs using plastic criteria (e.g. stain-based and limit-states designs), use of this part of ANSI/NACE MR0175/ISO 15156 might not be appropriate and the equipment/material supplier, in conjunction with the equipment user, shall assess the need for other requirements. This response does not address the issue that rupture discs plastically deform which is at the heart of and the basis of the previous inquiry.Metal rupture discs are made 8 to order product that plastically deform as part of the manufacturing process and will plastically deform when they burst (fail) when exposed to an overpressure process condition.

    Answer: 

    "The Maintenance Panel for NACE MR0175/ISO 15156 has reviewed your inquiry submitted May 4, 2012. You asked for further clarification of the answers to MP Inquiries #2009-05 and #2011-08.
    Here is the Maintenance Panel’s response:
    • The answer previously given has been confirmed to be correct by the Maintenance Panel (MP).
    • The MP also confirms there is no conflict with the reply given for Inquiry 2009-05.
    • Since the rupture disk is not a “Table A.1 exclusion,” it must either meet the material requirements in Annex A or be approved by the end user based on laboratory testing or field history. Confirming compliance with the material requirements in Annex A may be difficult for a rupture disk. However, it may be possible to demonstrate that the same raw material sheet with plastic deformation equivalent to worst-case locations on the rupture disk have metallurgical properties well within the material requirements in the standard.
    Additional comments from other MP members:
    1. On the issue of plastic deformation during manufacturing:
    -Whether the material is plastically deformed in fabrication is not the issue here.
    -Plastic deformation during manufacturing is irrelevant to clause 5, paragraph 9.
    2. On the issue of deformation during rupture:
    -Plastic deformation occurs when they burst, but then they’re intended to burst.
    -The rupture disk functions within its elastic limit during the pressure-containing (bulk) of its service life. They are not designed to operate after additional in situ deformation (i.e., no strain-based design). Plastic deformation on failure is incidental to the function.
    -The purpose of the wording in Part 1 Section 5 is to cover design criteria where the material is expected to function beyond the elastic limit in service without failing (strain-based designs for pipelines being a prime example). Bursting disks do not fall into this category, either being plastically deformed (cold worked) prior to service or suffering from plastic deformation incidental to failure (albeit failure is part of the function of the bursting disc in cases of over pressurization) in service."

    This question is in relation to NACE MR0175/ISO 15156-1 Clause 5

    Reference: ISO 15156 Maintenance Panel Inquiry #2012-04

    At Oil & Gas Corrosion we can help you with materials selection during design, whether you use elastic or plastic design criteria.

     

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  • 31. How can used and old equipment be certified to NACE MR0175?
     

    Question:

    My customer has some swab tanks that were manufactured in 1953; they are made of rolled 1/2-inch plate A283C; the tank is 84 in. in diameter and is rated for 100-psi service. The question is given the following conditions does this tank meet NACE MR0175? According to Section A2.1.6 the requirement that all rolled or deformed material must be stress relieved and have a hardness of 22 HRC max. The problem is we cannot or have no documentation as it relates to the heat treat of the plate post welding. yet when tested the material meets the A283C requirements and the hardness are in the 120-127 HB. Ultrasonic testing as part of a corrosion survey on the tank was performed and all was in order. Engineering approval was granted on the status of the vessel as a pressure vessel under the ABSA (Alberta Boilers Safety Association). This tank is 52 years old, is in excellent condition, and the customer wants to have more current documents on the tank as it relates to its status as an ABSA pressure vessel and it's NACE MR0175. With all this information can a determination be made that this material in its current state is suitable as a material that qualifies as a NACE MR0175/ISO 15156-compliant material? Using the long life, performance, and the mechanical data gathered can this determination be made? If so, can these criteria be used to establish a basis for performing future work on this exact style of tank?

    Answer:

    The ISO 15156 Maintenance Panel cannot advise on the suitability of this tank for use in sour service.

    It is the responsibility of the equipment user to assess the suitability of the material and to ensure compliance with NACE MR0175 / ISO 15156.

    Consideration of the following could contribute to any evaluation of suitability you undertake:-

    For some equipment NACE MR0175/ISO 15156-2, Table 1 allows the equipment user to categorize equipment as a "Permitted exclusion" where the operating pressure does not exceed 0.45 MPa (65 psi).

    NACE MR0175/ISO 15156-1, Clause 6 and in particular 6.2 d) offer some guidance on the fitness for purpose evaluation of materials in existing equipment.

    This question is in relation to NACE MR0175/ISO 15156-1 Clause 6

    Reference: ISO 15156 Maintenance Panel Inquiry #2005-31

    At Oil & Gas Corrosion our team of corrosion consultants and oilfield metallurgists can help you verify and document fitness for service even for old equipment in service.

     

    With a wealth of experience in the oil and gas industry, we provide independent materials and corrosion consultancy to help companies reduce risk, save money and apply best practice in their oil and gas businesses.

    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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  • 32. What are the NACE MR0175 requirements for C95800, C95400, C95500 and C63200?
     

    Question:

    We are using the following materials for manufacturing of valve components. In reference to the clause A.12.1 of NACE MR0175/ISO 15156-3:2003, no any special requirements are specified to these materials for use in SOUR environment. We wish to know what shall be the chemical, physical, hardness properties and heat treatment requirements for using these materials in SOUR service environment. Valve Components: Body – ASTM B148 UNS C95800, C95400 & C95500. Stem – ASTM B150 UNS C63200. Ball – ASTM B148 UNS C95800.

    Answer:

    For these materials, there are no 15156 restrictions on chemistry, hardness or heat treatment. However, note that these materials can undergo severe weight loss corrosion. They may also be susceptible hydrogen stress cracking when galvanically coupled to steel. It is up to the user to decide if qualification of these materials is necessary in the applicable sour service environment. § 8 of NACE MR0175/ISO 15156 Part 1 indicates how these materials can be qualified.

    This question is in relation to NACE MR0175/ISO 15156-1 Clause 8

    Reference: ISO 15156 Maintenance Panel Inquiry #2009-12

    At Oil & Gas Corrosion we help the industry understand and implement the NACE MR0175 requirements for copper, aluminium, titanium and other alloys.

     

    With a wealth of experience in the oil and gas industry, we provide independent materials and corrosion consultancy to help companies reduce risk, save money and apply best practice in their oil and gas businesses.

    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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  • 33. Successful field service? No documentation? What does NACE MR0175 require?
     

    Question:

    When materials in an existing field are replaced, what criteria should be used? Paragraph 8.2 of ISO 15156-1 provides some criteria for qualification, but it is not clear what approach should be used for materials that have been in use with no problems, but documentation does not exist.

    Answer:

    NACE MR0175/ISO 15156-1 Paragraphs 6.2, 8.1, 8.2, and 9.0 provide a complete description of the documentation required for two years’ successful field service. Documentation has always been required.

    This question is in relation to NACE MR0175/ISO 15156-1 Clause 8.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2003-41

    If you require to qualify an equipment based on field service but you are not sure how to complete the documentation contact us and we can help you.

     

    With a wealth of experience in the oil and gas industry, we provide independent materials and corrosion consultancy to help companies reduce risk, save money and apply best practice in their oil and gas businesses.

    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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  • 34. Does NACE MR0175/ISO 15156 require production casing to be sour service compliant?
     

    Oil & Gas Corrosion can help you select materials for tubing, casing and downhole components. We understand oilfield metallurgy and the role it plays in well integrity.

    Question: Does NACE MR0175/ISO 15156 require production casing to be sour service compliant if the containment string of tubing is a sour service grade and the bottom hole temperature (below the packer) satisfies the casing material operating temperature? For example--a sour gas well with a H2S partial pressure of 0.10 psi (0.007 bar), P-110 casing, L-80 tubing, and a bottom hole temperature of 300 F (150 C). Supporting Information: Related information can be found in NACE MR0175/ISO 15156-2, Table 1, page 2. Production casing is not excluded from meeting the requirements of ISO 15156. AND ISO 15156-1/NACE MR0175, Section 6, which is reproduced in part below with the relevant parts underlined. 6. Evaluation and definition of service conditions to enable material selection 6.1 Before selecting or qualifying materials using other parts of NACE MR0175/ISO 15156, the user of the equipment shall define, evaluate and document the service conditions to which materials may be exposed for each application. The defined conditions shall include both intended exposures and unintended exposures which may result from the failure of primary containment or protection methods. Particular attention shall be paid to the quantification of those factors known to affect the susceptibility of materials to cracking caused by H2S.

    Answer:

    1) As stated in your inquiry the secondary barrier must also be sour service and follow the requirements of NACE MR0175/ISO 15156.
    2) A casing grade can be used under severity 3 of the diagram Fig. 1 of § 7.2.1.2. provided its working temperature is always above the minimum temperature given in ISO 15156-2 Table A.3. This can only be true if the material is well defined (API grade) and its temperature is always above the minimum temperature. According to Table A.3 if P110 is at a temperature ≥80°C 175°F) it can be used in Region 3 of the diagram Figure 1 of §7.2 in ISO 15156-2. It is up to the equipment user to establish that all intended and unintended exposure conditions are covered.

    This question is in relation to NACE MR0175/ISO 15156-2 Clause 7.2.1.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2010-12

    alloy select is the only web-based software for materials selection of oil and gas assets and has been developed by the team of experts at Oil & Gas Corrosion. alloy-select can help you select materials for tubing and casing. To learn more about alloy-select visit alloyselect.com

    At Oil & Gas Corrosion we see help operators and contractors to select downhole metallurgy and to comply with NACE MR0175 and other regulatory requirements. Talk to our team today!

     

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    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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  • 35. Why does NACE MR0175 list S31600 and S31603 separately in part 3 Table A.2?
     

    Question: 

    Q1: Table A.2 lists material types and individual alloy UNS numbers. UNS S31600 and S31603 appear below the listing for ""Austenitic stainless steel from materials type described in A.2"" S31600 and S31603 comply with the requirements for material described in A.2 Why are S31600 and S31603 listed separately from the other austenitic stainless steels?

    Q2:Do S31600 and S31603 have different environmental limitations than other austenitic stainless steels?

    Answer

    A1-Clause A.2 materials permit less highly alloyed grades than S31600 and S31603.

    A2-Yes

    This question is in relation to NACE MR0175/ISO 15156-3 Table A.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2013-06

    We can provide support with NACE MR0175 and austenitic stainless steels. 

     

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  • 36. What are the NACE MR0175 requirements for expansion joints and flexible hoses in austenitic stainless steel?
     

    Question:

    We're a manufacturer of expansion joints and flexible hoses and since we get more and more often inquiries regarding bellow according to MR0175 we purchased a copy of this standard some time ago. Since our bellows standard material is austenitic stainless steel, we paid particular attention to Table A.2 (attached) where there some notes about cold work and maximum hardness. Our understanding of these notes is that to meet this particular requirement we have to perform a heat treatment of the bellows after cold forming and to check the maximum hardness to be not higher than 22 HRC. Could you please tell me if our understanding is correct or what is the right method to follow to satisfy the requirements of MR0175 when the subject is cold formed bellows?

    Answer:

    Table A.2 is applicable to austenitic stainless steels used for ANY components. There may be other applicable tables depending on the end use of the bellows (e.g. Table A.7 for gas lift service).
    If Table A.2 is the applicable table, the requirements for material conditions, hardness limit and cold forming are stated in A.2.
    The MP is restricted to providing interpretations of the standard’s requirements and may not provide direction beyond this scope.

    This question is in relation to NACE MR0175/ISO 15156-3 Table A.2 (cold work)

    Reference: ISO 15156 Maintenance Panel Inquiry #2012-03

     

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  • 37. What are the NACE MR0175 limits for Nitronic 50 (UNS S20910)?
     

    The NACE MR0175 received the inquiry shown below, if you need technical support on Nitronic 50 (UNS S20910) get in touch with us.

    Question:

    Our customer does not understand the NACE the same way as we do regarding the use of Nitronic 50 "hot worked" when applying Table A.3 (see document attached). It is only a matter of interpretation of the NACE and we are convinced that on the contrary Nitronic 50 should be used "hot worked" and can be used "cold worked" if preceded by an annealed treatment. The only way to convince them that they can use Nitronic 50 hot worked for their application, would be if we have someone from NACE who would certify that our interpretation above is correct.

    Answer:

    The following interpretation can be given for use of UNS S20910:
    “The note in Table A.3 permits the use of UNS S20910 in the solution annealed and cold worked condition provided that the hardness does not exceed 35 HRC. The solution annealed condition is also acceptable.
    Also, refer to Table A.2 which permits use of listed materials for any equipment or components. This Table contains the following note “S20910 is acceptable in the annealed or hot rolled (hot/cold worked) condition at a maximum hardness of 35 HRC”.
    If your question is of whether UNS S20910 is acceptable in hot worked conditions for the limits listed in Table A.3, we would ask you to re-phrase your inquiry to specifically ask for this. The standard is not using expressions such as “should be used” or “can be used” for limits given in the tables.
    Note that the answer to this is not clearly given in the standard and we will need some time to discuss the answer to this with the Maintenance Panel for the ISO 15156 / NACE MR0175.

    This question is in relation to NACE MR0175/ISO 15156-3 Table A.3

    Reference: ISO 15156 Maintenance Panel Inquiry #2014-09

    At Oil & Gas Corrosion we help clients to select materials such as Nitronic 50 (UNS S20910) and to comply with NACE MR0175.

    UPDATE 2018-06-01: A new technical circular for NACE MR0175 has been issued with changes that are relevant to Nitronic 50, read more: https://oilandgascorrosion.com/nace-mr0175-iso-15156-technical-circulars-for-part-2-and-3-published-2018-06-01/

     

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  • 38. NACE MR0175 and the maximum allowable case depth for nitriding to 0.006".
     

     

    Question:

    NACE MR0175/ISO 15156-2:2015 A.2.1.5 limits the maximum allowable case depth for nitriding to 0.006". Case depth is not defined in NACE MR0175/ISO 15156 and there are multiple definitions of case depth that are possible. Which of the following definitions of case depth is intended here?

    a) The total case depth (determined by metallographic analysis)

    b) The effective case depth, based on a difference of 50 HV between core and case

    c) The effective case depth, based on a difference of 10% between core and case

    d) The effective case depth, based on manufacturer spec of case hardness criteria

    e) Other – if so, please explain

    ANSWER:

    The measurement of case depth is not defined in NACE MR0175/ISO 15156. Adding a definition of the measurement criteria requires a ballot.

    Reference: ISO 15156 Maintenance Panel Inquiry #2016-01

    This question is in relation to NACE MR0175/ISO 15156-3 A.2.1.5

    Talk to us to discuss nitriding and NACE MR0175

     

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  • 39. NACE MR0175 and the requirements for HSC, GHSC and SSC
     

    Question:

    HSC describes cracking in metals that are not sensitive to SSC but which can be embrittled by hydrogen when galvanically coupled, as the cathode, to another metal that is corroding actively as an anode. The term “galvanically induced HSC” has been used for this mechanism of cracking. It means HSC is the same as "galvanically induced HSC" and different from SSC. But in NACE MR0175-1 clause 3.23 SSC is a form of hydrogen stress cracking (HSC) and involves the embrittlement of the metal by atomic hydrogen that is produced by acid corrosion on the metal surface. It means SSC is a type of HSC. The words from two paragraphs are contradictory. I think the words should be understood as below. There are two types of HSC. One is "galvanically induced HSC”, it is abbreviated as GHSC, because in NACE MR0175-3, clause 3.7,the definition galvanically induced hydrogen stress cracking cracking that results due to the presence of hydrogen in a metal, induced in the cathode of a galvanic couple, and tensile stress (residual and/or applied) The other one is "Sulfide induced HSC" .e.g "Sulfide Stress Crack"(SSC) because in NACE MR0175-1 clause 3.23, the definition is as below. SSC is a form of hydrogen stress cracking (HSC) and involves the embrittlement of the metal by atomic hydrogen that is produced by acid corrosion on the metal surface. Hydrogen uptake is promoted in the presence of sulfides. The atomic hydrogen can diffuse into the metal, reduce ductility and increase susceptibility to cracking. High strength metallic materials and hard weld zones are prone to SSC. Please help me if my understanding about HSC, GHSC, and SSC right or not?

    Answer:

    We thank you for your inquiry and agree that there is some confusion in the notes to these definitions. The HSC includes cracking in metals that are not sensitive to SSC but which can be embrittled by hydrogen when galvanically coupled, as the cathode, to another metal that is corroding actively as an anode. The term “galvanically induced HSC” has been used for this mechanism of cracking. We believe that this can be clarified by a ballot on our definitions; we are initiating the ballot process.

    This question is in relation to NACE MR0175/ISO 15156-1 3.1.3

    Reference: ISO 15156 Maintenance Panel Inquiry #2016-02

    Talk to us, our corrosion consultants will help you manage the risk of  HSC, GHSC and SSC.

     

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  • 40. is 3D printing considered within the scope of NACE MR0175 / ISO 15156?
     

    Can you please clarify if metal additive manufacturing (also referred as 3D printing) is a manufacture process considered within the scope of NACE MR0175 / ISO 15156?

    If the answer is negative, can you clarify if a material/alloy that is listed in NACE MR0175/ISO 15156 as acceptable for a certain environment and under certain metallurgical conditions is also considered acceptable when processed by 3D printing provided hardness limits are observed? E.g. if alloy UNS N07718 is listed as acceptable in the cast condition to a maximum hardness of 40HRC, would a N07718 component processed by 3D printing and with hardness below 40HRC is considered to meet the requirements of NACE MR0175 / ISO 15156?
    Q1: Is metal additive manufacturing (also referred to a 3D metal printing) a manufacturing process defined or included in NACE MR0175/ISO 15156?
    A1: 3D metal printing/metal additive manufacturing is not defined in NACE MR0175/ISO 15156.
    Q2: If the answer to Q1 is no, would a currently listed alloy be acceptable for a specific application if manufactured through 3D printing and final hardness limits were within requirements of NACE MR0175/ISO 15156?
    A2: In itself, this is not sufficient because 3D metal printing/metal additive manufacturing is not defined as an acceptable process route.
    Q3: If the answer to Q2 is no, would UNS N07718 manufactured through 3D printing be acceptable within the restrictions of the cast condition for UNS N07718 in NACE MR0175/ISO 15156-3 Table A.31 or Table A.32?
    A.3: The same answer to Q2 applies here; it is not known whether the 3D printed condition is equivalent to the cast condition defined for this alloy. To be acceptable, the production route would need to qualify in accordance with NACE MR0175/ISO 15156-3 Appendix B.

    This question is in relation to NACE MR0175/ISO 15156-2 Annex A.2.1.2 and A.2.2.2
    Reference: ISO 15156 Maintenance Panel Inquiry #2016-03

     

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  • 41. NACE MR0175 and cold work of 316L and other austenitic stainless steels.
     

    With reference to NACE MR0175 / ISO 15156-3 (2015), I am querying one of the comments under Note b (applicable to UNS S31603) in the notes section of Table A.2 which states; “after the final solution annealing and quenching treatment, hardness and cold work incidental to machining or straightening shall not exceed the limits imposed by the appropriate product specification”.
    The product specification ASTM A479 does not state a maximum hardness limit for UNS S31603. Cold drawing is permitted for straightening purposes under Supplementary Requirement S5 (related to SCC resistance) of ASTM A479, which ties in with ‘cold work incidental to straightening’ stated in your NACE MR0175 / I15156-3 (2015) standard. However, due to their being no hardness limit and also no clear limit on the amount of cold work (other than for straightening purposes) in this ASTM A479 product specification, what is your definition of these limits? Do we assume a maximum limit of 22 HRC stated under note ‘a’ in table A.2? Also, can a limit be placed on the material’s maximum yield and tensile strength (that correlates with the amount of permitted cold work) that does not compromise the material’s resistance to SCC?
    ANSWER:

    Q1: Referring to 15156-3 Table A.2, what is the definition of cold work limits for UNS S31603 with respect to straightening in accordance with ASTM A479 Supplement S5?
    A1: The cold work limit is not defined in Table A.2 only that the material shall be free of cold work intended to enhance mechanical properties.
    Q2: With the straightening cold work, can we assume that the hardness limit of 22 HRC applies?
    A2: Correct, the maximum hardness is 22 HRC.
    Q3: Can a limit on the material’s maximum yield and tensile strength be placed on the material that corresponds to the maximum permitted cold work?
    A.3: The maximum yield and tensile is not defined. During our discussions on the ballot regarding cold work of UNS S31603 and Table A.2, there was a lot of agreement that the maximum “specified minimum yield strength (SMYS)” needed to correspond to that of the annealed without cold work condition. However, there was not sufficient consensus to define what this maximum SMYS should be.
    Reference: ISO 15156 Maintenance Panel Inquiry #2016-04
    This question is in relation to NACE MR0175/ISO 15156-3 Table A.2

    Do you need technical advice on UNS S31603 and other austenitic stainless steels? Talk to our corrosion consultants and oilfield metallurgists.

     

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  • 42. What are the NACE MR0175 requirements for ASTM A216 Grade WCB valves?
     

    ASTM A216 WCB valves are widely used in hydrocarbon processing. NACE MR0175 is applicable when materials like ASTM A216 WCB are exposed to H2S. The sour service requirements for ASTM A216 WCB are included in NACE MR0175.

     

    What are the NACE MR0175 requirements for ASME IX P1 Group 1 and 2 materials? from Ivan Gutierrez on Vimeo.

    Ivan Gutierrez discusses the NACE MR0175 requirements for ASME IX P1 Group 1 and 2 materials.

    ASME IX P1 material is listed as acceptable in NACE MR0175, but this does not mean that the general requirements do not apply, i.e. hardness heat treatment, HIC resistance etc. At Oil & Gas Corrosion we can help you confirm material compliance to ANSI/NACE MR0175/ISO 15156.

    Our team is here to discuss ASTM A216 Gr WCB, ASME IX P1/P2 and NACE MR0175 / ISO 15156 compliance. Talk to us today!

     

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    Question:

    I am writing about one question which is not clear for me after reading “NACE MR0175/ISO 15156” My question is: whether this standard is applicable for valve casting material as ASTM 216WCB or not? I have read many time this standard, but just mentioned for pipe, and fitting products . Regarding attached file I have confused should I do HIC and SSC test on the valve casting components or not? Could you please deal with the question and let me know how I can find clear idea. Reference to Valve Magazine 18 January 2011 Materials Q&A

    Answer 1: If NACE MR0175/ISO 15156 is a requirement for the product then NACE MR0175/ISO 15156-2 Section 1 with Table 1 defines applicability. Valve materials are not listed in NACE MR0175/ISO 15156-2 Table 1 as a permitted exclusion. Therefore, valves must comply with the standard.

    Question 2: If yes, is ASTM A216 Grade WCB compliant? ASTM A216 grade WCB is a low carbon steel with 250 MPa (36 ksi) minimum yield strength in one of the following conditions: annealed, normalized or normalized & tempered.

    Answer 2: NACE MR0175/ISO 15156-2 Annex A Section A.2 lists the general compliance requirements for carbon and low alloy steels (including castings). One of the requirements of A.2.1.2 is that the hardness must be 22 HRC maximum. ASTM A216 Grade WCB could be compliant with the addition of the maximum hardness limit.

    Question 3: Am I required to perform HIC and SSCs test on the valve casting components?
    Answer 3: If all the requirements of NACE MR0175/ISO 15156-2 Annex A Section A.2 are met then Section A.2.1.1 states “Carbon and low-alloy steels, products and components that comply with A.2 are, with stated exceptions, qualified in accordance with this part of ISO 15156 without further SSC testing. Nevertheless, any SSC testing that forms part of a materials manufacturing specification shall be carried out successfully and the results reported.” NACE MR0175/ISO 15156-2 Clause 8 defines the need to perform HIC testing. As noted in Clause 8, castings with less than 0.025% Sulfur mass fraction are not normally considered sensitive to HIC or SOHIC
    Reference: ISO 15156 Maintenance Panel Inquiry #2016-05

    alloy select is the only web-based software for materials selection of oil and gas assets and has been developed by the team of experts at Oil & Gas Corrosion. alloy-select can help you verify mateerials compliance to NACE MR0175 and other industry standards. To learn more about alloy-select visit alloyselect.com

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  • 43. In Table A.3, is there a maximum hardness value for AISI 4130 Q & T with (140 ksi) yield for temperatures > 80°C?
     

    Question:

    In Table A.3, is there a maximum hardness value for AISI 4130 Q & T with (140 ksi) yield for temperatures > 80°C?

    Answer:

    4130 is not listed in Table A.3
    Reference: ISO 15156 Maintenance Panel Inquiry #2016-06
    This question is in relation to NACE MR0175/ISO 15156-2 A.2.2.3.3, Table A.2, and Table A.3

     

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  • 44. What are the NACE MR0175 hardness requirements for a buttweld with inner CRA cladding?
     

    It is understood that the section A.2.1.5 and Table A.1 of NACE MR0175 / ISO 15156-2 and section A.13.1 of NACE MR0175 / ISO 15156-3 for cladding, lining and overlay deal with the cladding, lining and overlay of the overall internal surface of a carbon steel component and in contact with the fluid. In the case of CRA girth welding of a clad pipe, it is understood that the above mentioned sections are not applicable to the carbon steel HAZ of the CRA girth weld (except the portion which crosses the carbon steel HAZ of the overlay). See  below figure. Could you confirm that our understanding is correct?

    ANSWER:
    NACE MR0175/ISO 15156-2 Section A.2.1.5 does permit the waiver of the maximum hardness requirements in accordance with NACE MR0175 / ISO 15156-3 Section A.13.1. The NACE MR0175 / ISO 15156-3 Section A.13.1 define the conditions and requirements for waiving the maximum hardness. Specifically, the user must demonstrate and document the likely long term integrity of the cladding or overlay. The long term integrity can be affected by (1) application of heat or stress-relief treatments, (2) environmental cracking under intended service conditions, (3) other corrosion mechanisms, (4) mechanical damage and (5) dilution of the overlay.
    This question is in relation to NACE MR0175/ISO 15156-2 A.2.1.4 and A.2.1.5

    Reference: ISO 15156 Maintenance Panel Inquiry #2016-07

    Talk to us to verify compliance with NACE MR0175.

     

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  • 45. Which NACE MR0175 table applies to 718 (regardless of heat treated condition)?
     

    If a Nickel alloy does not have any age / precipitation-hardening heat treatment applied to it, does this not make it a solid-solution type alloy, and therefore should be covered by  Tables A.12 to A.16 of the NACE standard instead?

    Regarding precipitation hardened Nickel based alloys, Tables A.31 to A.34 all have the heading ‘Environmental and materials limits for precipitation-hardened nickel based alloys used…….’. The heading gives the impression that all materials listed in the Tables A31. to A.34 are precipitation hardened type Nickel based alloys only, however in the notes sections in the Tables, the alloys are allowed to be in other conditions i.e. in Table A.32, wrought UNS N07718 is allowed to be in four different heat treated conditions including a solution-annealed condition, and a hot-worked condition (both of these conditions do not involve any age / precipitation-hardening).
    If a Nickel alloy does not have any age / precipitation-hardening heat treatment applied to it, does this not make it a solid-solution type alloy, and therefore should be covered by Tables A.12 to A.16 of the NACE standard instead?

    Question: If UNS N07718 precipitation hardened nickel base alloy in NACE MR0175/ISO 15156-3 is in the solution annealed condition, is this Table A.32 still applicable or should it be considered a solid solution nickel base alloy and Table A.14 would be applicable?

    Answer: UNS N07718 is considered to be a precipitation hardened nickel base alloy regardless of the heat treated condition; Table A.32 is the applicable Table as opposed to Table A.14.
    This question is in relation to NACE MR0175/ISO 15156-3 A.9 Table A.31
    Reference: ISO 15156 Maintenance Panel Inquiry #2016-08

    UPDATE 2018-06-04: A recent Technical Circular brings relevant updates on NACE MR0175 including Inconel 718: https://oilandgascorrosion.com/nace-mr0175-iso-15156-technical-circulars-for-part-2-and-3-published-2018-06-01/

    We are here to help you, talk to our team today!

     

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  • 46. Is there anything preventing someone from averaging HRV values right now?
     

    QUESTION:
    Section 7.3.2 of Part 2 of NACE MR0175/ ISO 15156 states that when hardness of parent metals are taken, after welding, using the Rockwell C method, as long as no individual reading is greater than 2HRC above the specified value, you are allowed to average several readings in close proximity. For example, if you punch a 23HRC (where 22 HRC max is the requirement), you can take 3 or 4 reading (e.g. 21, 21,22, 22) and if the average does not exceed 22, the test is valid and the qualification or procedure is successful. When using the HV5, HV10 or HRC 15N scales, the document is silent on averaging.
    If you look on the ASTM E140 conversion chart, 22 HRC is approximately 250 HV, and 20 HRC is approximately 234HV. In this hardness range there is basically a 16HV difference that equates to 2 HRC—or 8 HV points for every 1HRC point. It does not seem to make any technical sense to reject a weld procedure for being off say, 1 2 or 3 HRV points, which would amount to less than 0.5 HRC points. It seems to that averaging a few points (for example, if you punched a 252HV in one area) would be the logical and prudent thing to do.
    The basic question would be is there anything preventing someone from averaging HRV values right now? If there is, does the group feel that a formal ballot would be warranted?

    ANSWER:
    The referee hardness tests in for proving out isolated hard readings is not currently addressed in NACE MR0175/ISO 15156. A successful ballot would be required to add this into the standard.

    This question is in relation to NACE MR0175/ISO 15156-2 7.3.2 and 7.3.3
    Reference: ISO 15156 Maintenance Panel Inquiry #2016-10

    If you require support during a WPQR to meet NACE MR0175 contact us, we have the Technical Authority to help you.

     

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  • 47. Is HIC a potential risk if the partial pressure of H2S is below 0,3 kPa?
     

    Risks of HIC (and SWC) are mentioned in Clause 7.1.2 / Note 3, and reference is made to Clause 8. Clause 8 underlines that HIC shall be considered as potential risk in sour service even if only trace amounts of H2S are anticipated. This is puzzling, and I’d like you to help me on clarification:
    What does “trace amount” refer to? Is there a certain threshold? Is HIC not applicable as potential risk if the partial pressure of H2S is below 0,3 kPa (refers to Clause 7.1.1)? This interpretation is derived by the fact that HIC is not mentioned in Clause 7.1.1. On the other hand, this interpretation – on first sight – is not reasonable: As there is no threshold for H2S with regard to HIC (Clause 8), HIC -from my point of view – must considered as risk, and should be mentioned already in Clause 7.1.1.
    The present ISO design implies that HIC only is of concern if Clause 7.1.2. is applicable. And this – in turn – is a contradiction to Clause 8. Please (1) clarify the misunderstanding / misinterpretation from my side and (2) advise on how to handle the risks of HIC in case of Clause 7.1.2:
    Is Clause 8 valid or not?

    ANSWER:
    This inquiry pertains to Risks of HIC (and SWC) that are mentioned in NACE MR0175/ISO 15156-2 Clause 7.1.2 / Note 3 with reference to Clause 8. Clause 8 underlines that HIC shall be considered as potential risk in sour service even if only trace amounts of H2S are anticipated.
    Question 1: What does “trace amount” refer to? Is there a certain threshold?
    Answer 1: This is not defined in NACE MR0175/ISO 15156-2.
    Question 2: HIC is not mentioned in Clause 7.1.1. Is HIC not applicable as potential risk if the partial pressure of H2S is below 0,3 kPa (refers to Clause 7.1.1)? Is  Clause 8 Valid considering that Clause 7.1.1 does not list HIC?
    Answer 2: The NOTES in Clause 7.1 apply to both Clauses 7.1.1 and 7.1.2; for HIC and SWC, you are referred to Clause 8.
    This question is in relation to NACE MR0175/ISO 15156-2 7.1.2
    Reference: ISO 15156 Maintenance Panel Inquiry #2016-11

     

     

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  • 48. NACE MR0175 and the evaluation and acceptance criteria for the Four Point Bend (FPB) test
     

    QUESTION:
    This inquiry for help with interpretation concerns the clause NACE MR0175/ ISO 15156-2 B.4.2.3 Evaluation and acceptance criteria for FPB test specimens.
    1) It is written “Damage developed on the tensile side of a specimen in the form of blisters less than 1 mm below the surface, or on the compression side regardless of the depth of the blister, may be disregarded for the assessment of SOHIC/SZC but shall be reported”
    Question : Does this means that Damage developed on the tensile side of a specimen in the form of blisters MORE than 1 mm below the surface has to be considered as not allowed/not acceptable or should only be reported as “blisters more than 1 mm below the surface”? (See below) Example 1: No blisters deeper than 1mm in the tension side are allowed (?)
    2) It is written “No ladder-like HIC features nor cracks exceeding a length of 0.5 mm in the through thickness direction are allowed”
    Question: Are cracks developed inside an area affected by a blister disregarded for the assessment (cf. example 2 picture)? In other words: Shall the damage in example 2 be reported as:
    A) a blister?
    B) a crack?
    C) a blister and a crack?
    ANSWER:
    Question 1: “Damage developed on the tensile side of a specimen in the form of blisters less than 1 mm below the surface, or on the compression side regardless of the depth of the blister, may be disregarded for the assessment of SOHIC/SZC but shall be reported”. Does this means that Damage developed on the tensile side of a specimen in the form of blisters MORE than 1 mm below the surface has to be considered as not allowed/not acceptable or should only be reported as “blisters more than 1 mm below the surface”?
    Answer 1: Blisters greater than 1 mm below the surface are not acceptable.
    Question 2: “no ladder-like HIC features or cracks exceeding a length of 0.5 mm in the through thickness direction is allowed”. Are cracks developed inside an area affected by a blister disregarded for the assessment (cf. example 2 picture)? In other words: Shall the damage in example 2 be reported as:
    A) a blister?
    B) a crack?
    C) a blister and a crack?
    Answer 2: if both cracks and blisters are present as defined Clause B.4.2.3, they both need to be reported.
    This question is in relation to NACE MR0175/ISO 15156-2 B.4.2.3
    Reference: ISO 15156 Maintenance Panel Inquiry #2016-12

    UPDATE: A new standard for Four Point Bend has been published by NACE. NACE TM0316 2016 addresses four point bend testing for sour service. Read a review of the document following this link:

    https://oilandgascorrosion.com/new-nace-tm0316-2016

    Contact us to discuss Four Point Bend testing requirements.

     

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  • 49. In NACE MR0175, is UNS S41425 sulfur resistant in Table A.18?
     

    QUESTION:
    Material grade S41425 is listed as not being sulfur resistant in Table A.18 — “Environmental and materials limits for martensitic stainless steels used for any equipment or components”, ANSI/NACE MR0175/ISO 15156-3:2015(E). For the column ‘Sulfur resistant?’, it says ‘No’. I wanted to confirm that was indeed a correct designation, and not an error.
    (MP INQUIRY #2016-13)
    ANSWER:
    No and it is not a misprint.
    This question is in relation to NACE MR0175/ISO 15156-3 A.6.2 Table A.18
    Reference: ISO 15156 Maintenance Panel Inquiry #2016-13

     

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  • 50. What are the NACE MR0175 material requirements for Inconel 625 (UNS N06625)?
     

    Sour service material manufactured with Inconel 625 (UNS N06625) has to comply with ANSI/NACE MR0175/ISO 15156. NACE MR0175 provides the metallurgical requirements for Inconel 625. Metallurgical condition and hardness are two of those requirements discussed in this article.

    NACE MR0175 requires alloy 625 to be in the annealed condition. Some suppliers offer alloy 625 quenched off the hammer. This question was raised to the maintenance panel.

    Question: Is Alloy N06625 (Name - Alloy 625) material meet NACE MR0175/ISO 15156-3, Table A.13 if forged material is quenched off the hammer as opposed to performing a separate annealing?

    Answer:

    It is up to the Manufacturer to determine if alloy 625 is annealed under these conditions. It is not the role of the MP to answer metallurgical questions. If alloy 625 is annealed then it meets requirements of Table A.13.

    Question:

    What is the NACE MR0175 hardness requirement for Inconel 625 (UNS N06625)?

    Answer:

    NACE MR0175 / ISO 15156 Part 3 Clause A.4 provides details of material requirements for solid solution nickel alloys. 

    At Oil & Gas Corrosion we help manufacturers determine the optimal route for forging and annealing Alloy 625. We also help users review material test reports (MTRs) and manufacture documentation to confirm compliance with NACE MR0175 and other regulatory requirements.

    UPDATE 2018-06-04: A recent Technical Circular brings relevant updates on NACE MR0175 and 625 weld overlays: https://oilandgascorrosion.com/nace-mr0175-iso-15156-technical-circulars-for-part-2-and-3-published-2018-06-01/

    We are here to help you, talk to our team today!

     

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  • 51. What does NACE MR0175 mean by "Qualification based upon field experience"?
     

     

    Question:

    Q1: I need some clarifications on the clause 8.2 of the MR0175/ISO 15156-1 (Qualification based upon field experience). “A material may be qualified by documented field experience”--”the duration of the documented field experience shall be at least two years. . . “ What kind of documentation is expected? We need to know exactly what to ask from the end user. Is a letter describing the conditions for which the material qualified for the past two years enough?

    A1: NACE MR0175/ISO 15156-1, Paragraphs 6.2, 8.1, 8.2, and 9.0 provide a complete description of the documentation required for two years’ successful field service. Documentation has always been required.

    Q2: What do we (the equipment manufacturer) do with this documentation (field service qualification)?

    A2:The equipment user is responsible for the preparation of the required documentation (see NACE MR0175/ISO 15156-1, Clause 9, Paragraph 1 to support the use of a material in a plant on the basis of field experience. It would also be in the equipment user’s interest to keep copies of this documentation in their records in case they are challenged to prove they are responsible operators. The equipment manufacturer can choose to retain a copy for future reference.

    Q3: Does it have to be filed with NACE? If yes, is this our responsibility?

    A3: It is not the responsibility of the equipment manufacturer to file information with NACE, unless they choose to. This may be the case because the equipment manufacturer has made the effort to compile a non-proprietary database that they believe supports the use of alloys for their equipment under the conditions documented by the process in Question One.

    Q4: If filing (field service documentation) with NACE is not required, do we have to verify the claims or can we just provide the materials as requested by the end user?

    A4: The manufacturer can provide this information to a user, but it is the user’s responsibility to determine the operating conditions and select the appropriate materials. It is the manufacturer’s responsibility to meet the metallurgical requirements of the appropriate alloys in NACE MR0175/ISO 15156.

    This question is in relation to NACE MR0175/ISO 15156-1 Clause 8.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2004-05

    If you need to qualify equipment based on field service but you are not sure how to complete the documentation contact us, we can help you.

     

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  • 52. What happens to equipment and material certified to old NACE MR0175 versions?
     

    Question:

    How should existing equipment affected by changing materials requirements in later editions of the standard be handled?

    Answer:

    By convention, a new version of the standard is not applied retrospectively to equipment built to the previous version of the standard valid at the time of equipment construction.

    New requirements in the latest version may be applied retrospectively by an equipment user or mandated for retrospective application by a regulatory authority.

    This question is in relation to NACE MR0175/ISO 15156-1 Clause 8.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2005-10

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  • 53. According to NACE MR0175, compressive stress means exclusion or waiver?
     

    Question:

    MR0175 part 2, Table 1: Does the intent to only load in compression, regardless of resultant stresses, fulfill the requirement for exclusion?

    Answer:

    The exclusion applies to components loaded in compression. It does not apply to equipment, assemblies, or aggregate parts loaded in compression. However, due to part geometry, constraint, bending, friction, or other factors, local stresses within a single component may have a significant tensile element. In such cases the likelihood of environmental cracking, and its consequences, shall be considered before invoking this exemption.

    This question is in relation to NACE MR0175/ISO 15156-2

    Reference: ISO 15156 Maintenance Panel Inquiry #2015-04

     

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  • 54. Equipment of a SAGD plant, is it covered by NACE MR0175?
     

    Question: Regarding Table 1 in NACE MR0175/ISO 15156-2 is it defined what field facilities and field processing plants include? Would this include a SAGD plant? Also, when using below 65 psi for exclusion does this stand true for all: liquid, vapour, or mixed streams, also in Table 1?

    Answer:

    SAGD plant is not specifically included in Table 1 because it is not a “conventional” technique of oil production. However, it is up to the user to determine if some parts of a SAGD process may fit with the listed permitted exclusions. Please refer to answer to Inquiry #2009-14 for the second part of the question.

    This question is in relation to NACE MR0175/ISO 15156-2

    Reference: ISO 15156 Maintenance Panel Inquiry #2010-01

     

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  • 55. Is HIC Resistance "included" when specifying NACE MR0175?
     

    Question: Does requiring/specifying steel compliance to ANSI/NACE MR0175/ISO 15156-2 in a purchase order include resistance to HIC as well as other forms of sulfide cracking, or must HIC resistance be specifically required separately in the purchase order?

    Answer:

    ISO 15156 / NACE MR0175 covers all cracking mechanisms caused by H2S to be addressed for materials exposed in production environments. This includes HIC/SWC as stated in the scope for Part 2. Section 8 in ISO 15156 / NACE MR0175 Part 2 describes how carbon and low alloy steels shall be evaluated for their resistance to HIC/SWC. Test procedures and acceptance criteria to evaluate the resistance of carbon and low-alloy steels to HIC/SWC are described in B.5. As only flat-rolled carbon steel products are susceptible to HIC/SWC, section 5.2 requires that “requirements for HIC resistance” are provided in the purchasing specification. Note that a list of information must be included in the purchase order (note also the use of the word “shall” in the section) that includes “requirements for HIC resistance”.

    This question is in relation to NACE MR0175/ISO 15156-2 Clause 5.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2014-02

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  • 56. NACE MR0175, Carbon steels and further questions on SOHIC, SZC, SSC, HIC and SWC?
     

    Question: I have two questions concern hydrogen induced cracking. Question 1. Clause 7 of the standard is headed "Qualification & selection of C and low alloy steels with resistance to SSC, SOHIC and SZC" Clause 7.1.1 concerns SSC only in low partial pressure of H2S. There is no mention of the other forms of cracking. Clause 7.1.2 has three footnotes: NOTE 1 deals with SSC, NOTE 2 concerns SOHIC and SZC and NOTE 3 concerns HIC and SWC.Should these three NOTES be applied to Clause 7.1.1 too? Question 2. Clause 8 deals with the evaluation of C and low alloy steels for their resistance to HIC/SWC. It indicates that a few ppm of H2S must be considered during an evaluation of a steel. But have the steels that meet the requirements of Appendix A.2 been deemed to have been evaluated for HIC/SWC and so do not need additional HIC testing?

    Answer 1

    The applicability of Notes 1, 2, and 3 is for the entire Clause 7.1 and not restricted to Clause 7.1.2.

    Answer 2

    Materials described in Annex A.2 may require additional testing to confirm resistance to SOHIC, SZC, and/or SWC. This shall be determined by the equipment user and can be influenced by factors such as whether the material was produced as a flat rolled carbon steel product and the steel chemistry (see clause 8).

    Question 1 is in relation to NACE MR0175/ISO 15156-2 Clause 7.1

    Question 2 is in relation to NACE MR0175/ISO 15156-2 Clause 8

    Reference: ISO 15156 Maintenance Panel Inquiry #2012-12

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  • 57. What is the minimum partial pressure of H2S that requires compliance with NACE MR0175?
     

    What is the minimum partial pressure of H2S that requires compliance with NACE MR0175? What is the maximum ppm of H2S allowed without NACE MR0175?

    NACE MR0175 is an international standard that provides the requirements for metallic materials exposed to H2S in oil and gas production environments. In NACE MR0175, the presence of H2S is quantified as the partial pressure of H2S. The material requirements, as well as environmental limits, are based on ppH2S. In this video the lower limit of ppH2S for NACE MR0175 compliance is discussed.

     

    ANSI/NACE MR0175/ISO 15156 indicates that in production conditions with partial pressure of H2S (ppH2S) below 0.3kPa (0.05psi) no special precautions are required for carbon and low alloy steels. However highly susceptible carbon and low alloy steels (high strength, heavily cold worked etc) can still be susceptible to H2S related damage mechanisms even at ppH2S below these limits. Furthermore, the risk of Hydrogen Induced Cracking is present even at partial pressure of H2S (ppH2S) below 0.3kPa (0.05psi).

    For corrosion resistant alloys (CRAs) there is now ppH2S low limit, which means precautions need to be taken whenever the possibility of H2S is present.

    At Oil & Gas Corrosion our team can help you evaluate sour service production environment and confirm if NACE MR0175 applies to your equipment, talk to us today!

     

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    To find more information visit our Frequently Asked Questions sections to access more information on NACE MR0175.

    Question:

    NACE MR0175 / ISO 15156-2 Para 7.1.2 says "If the partial pressure of H2S in the gas is equal to or greater than 0.3kPa (0.05psi), SSC-resistant steels shall be selected using A.2" Could I please get clarification regarding the sour service H2S partial pressure cut-off value as NACE MR0175 / ISO 15156 use both imperial and metric units. The conversion of 0.05 psi is 0.345 kPa. Please clarify if the H2S pp cut-off for sour service is 0.3 kPa or 0.345 kPa (conversion from 0.05 psi).

    Answer:

    The value was rounded off when converting from 0.05 psi. This limit is actually not a very sharp and accurate value and this is why 0,3 kPa value was taken as a practical engineering value. Note, however, that even below this H2S partial pressure, some materials can be susceptible to SSC as stated in 7.1.1. This means that in principle there is no cut-off value for sour service. It is just that below this value, only particularly sensitive steels can be susceptible to SSC. It is up to the user to make sure that the steel used is resistant below 0.05 psi (0.3 kPa).

    This question is in relation to NACE MR0175/ISO 15156-2 Clause 7.1.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2009-18

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  • 58. NACE MR0175 SSC Resistant Steels above 0.3 kPa (0.05 psi) and the acceptable pH and Cl- limits
     

    Question: Sub-clause 7.1.2 says SSC Resistant Steels for partial pressures equal to or above 0.3 kPa (0.05 psi) can be selected using A.2. a) If criteria, like temperature, hardness are met, do we assume that for all partial pressures above 0.05 psi the suggested SSC-resistant materials could be used? E.g., SSC-resistant materials mentioned in Table A.2 and Table A.3. b) What are the acceptable pH and Cl- limits? c) Does A.2.2.3.3 cover L80 type 1? d) For low-alloy steels described in Section A.2 of this standard, what are the cases where injection of corrosion inhibitors are required, both for downhole casings/tubing and surface pipelines?

    Answer:

    a) This is correct.
    b) No limits of pH and Cl- have been formally defined for carbon and low-alloy steels. Any combinations of chloride concentration and in situ pH occurring in production environments are considered acceptable. Metal loss corrosion, which can be influenced by both pH and chlorides, is not the subject of the standard.
    c) No, this grade is covered in Paragraphs A.2.2.3.1 and A.2.2.3.4.
    d) NACE MR0175/ISO 15156 does not cover the use of corrosion inhibitors. The use of any kind of corrosion inhibitor is not considered to allow any relaxation of the requirements for cracking resistance of materials in sour service.

    This question is in relation to NACE MR0175/ISO 15156-2 Clause 7.1.2, A.2.2.3.3, Table A.2, and Table A.3

    Reference: ISO 15156 Maintenance Panel Inquiry #2005-14

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  • 59. In NACE MR0175, what is the maximum H2S partial pressure for carbon steel?
     

    Question:I was wondering if you could assist me in interpreting the partial pressure limitation for Carbon Steels referenced in part 2 section 7.1.2 and A.2. Is there a partial pressure max limit for carbon steels? If so, where is the reference in NACE MR0175/ISO 15156?

    Answer:

    The partial pressure mentioned in Section 7.1.2 is the partial pressure of H2S in the gas phase in equilibrium with the water in the production fluid. Annex C gives information on how to calculate H2S partial pressure.
    Regions 1, 2, and 3, Figure 1, cover usual conditions above 0.3 kPa. Note 1 mentions the unknown performance of steels above 1 MPa. The maximum partial pressure limit for carbon steels depends on many variables as noted in 15156-2 Clause 6. Currently a NACE TM0177 test with 100 kPa H2S, ~2.7 pH, room temperature, 50 g/L NaCl is considered to cover all normal production conditions for carbon steels.

    This question is in relation to NACE MR0175/ISO 15156-2 Clause 7.1.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2010-09

     

     

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  • 60. Difference between the NACE MR0175 requirements of SSC and HIC/SWC
     

    Question: There is ambiguity between two passages, they contradict, paragraph 7.2.1.2 “SSC regions of environmental severity” of NACE MR0175/ISO 15156-2:2009 (E) to 17 Paragraph 8, “Evaluation of carbon and low alloy steels for their resistance to HIC/SWC” of NACE MR0175/ISO 15156 – 2:2009 (E) The paragraph 7.2.1.2 for Region 0 – For pH2S <0.3 kPa (0.05 psi) “ Normally, no precautions are required for the selection of steels for use under these conditions, whereas paragraph 8, says even trace amounts of H2S and shall consider HIC/SWC testing of these products” In addition the Sulfur restriction in the chemistry of.003% maximum.

    Answer:

    “Your quoted passages of the standard are not contradictory. The standard provides different qualification requirements for different materials and different potential cracking modes. Clause 7 is for “- - steels with resistance to SSC, SOHIC, and SZC”. 7.2.1.2 & 7.2.1.3 are only applicable to SSC. Clause 8 is for “Evaluation of carbon and low alloy steels for their resistance to HIC/SWC”. For carbon steel products made from rolled plate, in addition to consideration of SSC resistance, HIC/SWC shall be considered (clause 8) and SOHIC and SCZ should be considered (clause 7.2.2).”

    This question is in relation to NACE MR0175/ISO 15156-2 Clause 7.2.1.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2012-09

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  • 61. In NACE MR0175, what does the uncertainty below 0.3 kPa mean?
     

    Question: There is the sentence in the note 1 of Figure 1 in ISO 15156-2: "The discontinuities in the figure below 0.3 kPa (0.05 psi) and above 1 MPa (150 psi) partial pressure H2S reflect uncertainty with respect to the measurement of H2S partial pressure (low H2S) and steels performance outside these limits (both lower and higher H2S)." I understand the above sentence, and if I will use the carbon steel and low-alloy steel in the sour service above 1 MPa (150 psi) of partial pressure of H2S, what can I do? Should I require a special laboratory test imitating the H2S partial pressure and pH in the service for SSC of the carbon steel and low-alloy steel? Which solution can I use in the special laboratory test? NACE TM0177 A solution or the imitating solution in the service?

    Answer:

    The following response must be seen in the context of NACE MR0175/ISO 15156-2, Clause 7.

    1. NACE MR0175/ISO 15156-2, Fig. 1 is a schematic definition of Regions of environmental severity with respect to SSC of carbon and low alloy steels. As mentioned in Paragraph 7.2.1.4, qualification for the use of a material not listed in Annex A for use in one or more of the Regions of Fig. 1 is always dependent on reported field experience or laboratory testing.
    There is little documented evidence that describes the SSC resistance of carbon and low alloy steels in H2S-containing environments outside the H2S limits of Fig. 1. The Note quoted reflects this.

    2. The equipment user must decide whether the listing of a steel in Annex A serves as an adequate guide for its behavior in H2S-containing field environments that might be more severe with respect to SSC than those represented by the SSC testing methods normally used; see Annex B.1a).
    For qualification for a specific application all the test conditions must be at least as severe, with respect to the potential mode of failure, as those expected to occur in field service.

    This question is in relation to NACE MR0175/ISO 15156-2 Clause 7.2.1.2, Fig 1

    Reference: ISO 15156 Maintenance Panel Inquiry #2005-17

     

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  • 62. According to NACE MR0175, who is responsible to ensure sour service conditions are qualified?
     

    Question: As stated in Part 1 Clause 5: "Qualification, with respect to a particular mode of failure, for use in defined service conditions also qualifies a material for use under other service conditions that are equal to or less severe in all respects than the conditions for which qualification was carried out. " The diagram Fig 1 Part 2 defines the severity in terms of the main environmental parameters, i.e., H2S partial pressure and pH but other parameters (temperature, stress level ...) must also be considered. It is the equipment user's responsibility to ensure the service conditions are equal or less severe "in ALL respects."

    Answer

    1. This interpretation is correct for SSC qualification only since this diagram applies to SSC. If a material is qualified at a point in the diagram, it will be qualified for any conditions less severe than these conditions, i.e., higher pH and/or lower H2S partial pressure.
    2. The diagram Fig 1 Part 2 defines the severity in terms of the main environmental parameters, i.e., H2S partial pressure and pH but other parameters (particularly stress level, temperature ...) must also be considered.
    3. It is the equipment user's responsibility to ensure the service conditions are equal or less severe "in ALL respects."
    4. Guidance is also given in Part 1 Clause 5: "Qualification, with respect to a particular mode of failure, for use in defined service conditions also qualifies a material for use under other service conditions that are equal to or less severe in all respects than the conditions for which qualification was carried out".

    This question is in relation to NACE MR0175/ISO 15156-2 Clause 7.2.1.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2009-23, Part 1

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  • 63. In NACE MR0175, is 0.3kPa ppH2S the lower limit for sour service compliance? What happens at lower partial pressures of H2S?
     

    What is the minimum partial pressure of H2S that requires compliance with NACE MR0175? from Ivan Gutierrez on Vimeo.

    At Oil & Gas Corrosion we can help you define the sour service requirements including CRA selection and HIC resistance at low ppH2S.

    Our team can help you evaluate materials selection at ppH2S below 0.3kPa. Talk to our team today!

     

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    Question 1: I am preparing a “position” document regarding SSC on behalf of my company. I am trying to understand the NACE definition for sour/non-sour (with relation to NACE MR0175). The definition of sour service is provided by NACE. That states, “exposure to oilfield environment that contain H2S and can cause cracking by the mechanisms addressed by this part . . .” However, this needs further qualification as the environmental conditions (degree of H2S and pH) may determine whether cracking can result. This is found in 7.2.1.3 of part 2 within NACE MR0175/ISO 15156, the document that refers to carbon steel (ISO 15156-2). For environments with a partial pressure of H2S below 0.3 kPa (0.05 psi) the document states, “Normally, no precautions are required for the selection of steels for use under these conditions”

    Answer 1: There is no “non-sour” limit as some steels can still be susceptible below the limit of 0.05 psi (0.3 kPa).

    This question is in relation to NACE MR0175/ISO 15156-2 Clause 7.2.1.3

    Reference: ISO 15156 Maintenance Panel Inquiry #2009-11, Part 1

    Part 2: While not explicitly stated, the implication of that statement is that an environment with a partial pressure below 0.3 kPa is regarded as “non-sour.” This is reinforced later, where Annex C, C.2 defines H2S partial pressure isobars to determine “if a system is sour.” Line 1 of Figure C.1 (0.3 kPa) identifies the demarcation between “sour” and “non-sour” conditions (referred to as being in accordance with Option 1, where environments below 0.3 kPa require no precautions), while lines 2-5 identify the degree of sourness (Option 2—prequalification of material or specific testing needs to be performed).

    Answer 2: In addition for CRAs, 15156-3 has no defined “non-sour” limit. Due to the wide range of environmental cracking resistance of CRAs, particularly those not listed in 15156-3, a non-sour limit would be so low (i.e., minimum detection level) that it would be useless.

    Reference: ISO 15156 Maintenance Panel Inquiry #2009-11, Part 2

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  • 64. Does ISO 15156-2, 7.3.2 also apply to low-alloy martensitic steels such as CA6NM ?
     

    Question:

    Does the MR0175/ISO 15156-2, 7.3.2 also apply to low-alloy martensitic steels such as CA6NM which is in fact considered a CRA (MR0175/ISO 15156-3)?

    Answer:

    No, it does not. Please see ISO 15156-3, 6.2.1 and ISO 15156-3, A.6.2, Table A18.

    This question is in relation to NACE MR0175/ISO 15156-2 Clause 7.3.2 and 7.3.3

    Reference: ISO 15156 Maintenance Panel Inquiry #2004-18 Q2

     

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  • 65. For Hardness (vickers HV), What is NACE MR0175 retesting criteria?
     

    Question: Typically, when an indentation fails the micro hardness test several additional indentations are made and measured in the same area as the suspect indentation on the same weld test coupon. The results are then averaged. If the additional indentations average is acceptable, the survey is considered acceptable. This is in line with the NACE MR0175 Part 2 Section 7.3 “Hardness” paragraph 7.3.2 “Parent Materials” which allows additional hardness readings in the adjacent areas of a failed hardness reading. Logically, the same testing methodology would apply to welds, even though it is not specifically stated in the standard and subsequent paragraphs of Part 2. I would like to clarify if the above is acceptable with regards to Vickers HV 10 micro hardness testing / re-testing requirements for welds while conforming to NACE MR0175 Section 7.3.3 Welds.

    Answer:

    Maximum acceptable hardness values for carbon steel, carbon-manganese steel and low-alloy steel welds are given in Table A.1.
    No individual readings above these limits are acceptable for welds.

    Reference: ISO 15156 Maintenance Panel Inquiry #2014-07

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  • 66. In the NACE MR0175 butt weld survey criteria, what is the acceptance criteria of middle points?
     

    Question:

    Ref Part 2 Figure 2 Butt Weld Survey method for Vickers Hardness Measurement. Location points 17, 18 & 19. What are the acceptance criteria? Table A.1 only provides acceptance for the Weld Cap and Root. As the area is not exposed should the acceptance level be 275 HV 10?

    Answer:

    Since it is not at the cap the acceptance level should be 250 HV 10 unless it is proven that it can be relaxed. For now there is no demonstrated evidence to show that 250 Hv can be relaxed at location points 17, 18, and 19 of Part 2 Figure 2.

    This question is in relation to NACE MR0175/ISO 15156-2 Clause 7.3.3 Figure 2 Table A.1

    Reference: ISO 15156 Maintenance Panel Inquiry #2009-04

    Talk to one of our welding engineers or our corrosion consultants to discuss WPQR/WPS and NACE MR0175

     

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  • 67. According to NACE MR0175, is 22HRC and PWHT required?
     

    Question:

    Section 7.3.3.2 states: "The HRC method may be used for welding procedure qualification. . . And the welding procedure specification includes post-weld heat treatment" and Clause A.2.1.4 states: "As-welded carbon steels, carbon manganese steels and low alloy steels that comply with the hardness requirements of Table A.1 do not require postweld heat treatment." It is confusing whether the latter statement implies that an as-welded carbon steel, carbon manganese steel, or low alloy steel would require a PWHT if only HRC hardness testing is performed. Per Section 7.3.3.2, I would say yes it does require PWHT. But if the as-welded hardness survey meets the 22 HRC limit then doesn't the as-welded material "comply with the hardness requirements of Table A.1 as stated in clause A.2.1.4?

    Answer:

    For carbon, carbon manganese, and low alloy steels hardness testing for welding procedure qualification (PQR) may be performed by the HRC method only if the design stress does not exceed 2/3 SMYS and PWHT is perform. If PQR hardness testing is performed by the 7.3.3.2 specified HV or HR15N methods, the restrictions for design stress and PWHT are not required.

    This question is in relation to NACE MR0175/ISO 15156-2 Clause 7.3.3.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2011-14

    Contact us to discuss the NACE MR0175 requirements and your welding procedure qualification, we are here to help.

     

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  • 68. According to NACE MR0175/ISO 15156, is there a maximum sulfur content for carbon steel SMLS pipe?
     

    What is the acceptable sulfur content to meet NACE MR0175 and HIC resistance? Our team can help you comply with NACE MR0175

    Question: According to NACE MR0175/ISO 15156, Part 2, Paragraph 8, HIC test is not mandatory for carbon steel SMLS pipe. But what about maximum sulfur content? Do we have to apply maximum sulfur content requirement to carbon steel regardless of HIC test?

    Answer:

    There are no requirements for the control of the chemistry of any elements to prevent HIC in NACE MR0175/ISO 15156. Some guidance concerning acceptable sulfur levels is given in Section 8 of NACE MR0175/ISO 15156 Part 2. For seamless products, testing can also be performed according to Table B.3 if deemed necessary.

    This question relates to Part 2, paragraph 8

    Reference: ISO 15156 Maintenance Panel Inquiry #2005-15

    alloy select is the only web-based software for materials selection of oil and gas assets and has been developed by the team of experts at Oil & Gas Corrosion. alloy-select can help you verify that materials like seamless pipe comply with the requirements of ANSI / NACE MR0175 / ISO 15156, API 5CT, API 5L and more. To learn more about alloy-select visit alloyselect.com

    Our team can help you specify the sulphur content on seamless pipe to comply with NACE MR0175 and HIC resistance requirements. Talk to our team today, we are here to help you.

     

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  • 69. NACE MR0175 does not mention clearly about sulfur restrictions for carbon steels such as ASTM A105 and A216. What are the sulfur limits?
     

    At Oil & Gas Corrosion we can help you specify the sulphur limits for carbon and low alloy steels and to comply with NACE MR0175.

    NACE MR0175 / ISO 15156 -2 in section 8 states:

    "The probability of HIC/SWC is influenced by the steel chemistry and manufacturing route. The level of sulfur in the (carbon and low alloy) steel is of particular importance"

    At Oil & Gas Corrosion we help clients to develop material specifications that specify sulfur contents in order to meet NACE MR0175 / ISO 15156 and that consider integrity threats throughout service life, including HIC, SWC and SOHIC.

    We also help clients that need to clarify the sulfur requirements during fabrication and when there is no project specification to use as reference.

    We can help you make the correct decision. Talk to us today.

    Question: NACE MR0175 /ISO 15156 does not mention clearly about sulfur restrictions for carbon steel forgings and castings to ASTM-A105 and ASTM-A216 respectively. These two specs are work-horse of any oil/gas processing industry. Almost 75% to 90% of materials of construction would fall into these specifications. For example: flanges and fittings and valves and rotating machinery casings. The paragraph A.2.1.3 states: A.2.1.3 Carbon steels acceptable with revised or additional restrictions In addition to the restrictions of A.2.1.2, some carbon steels are acceptable subject to the revised or additional restrictions as follows. a) Forgings produced in accordance with ASTM A 105 are acceptable if the hardness does not exceed 187 HBW. Please note: In the original standards ASTM-A105 allows sulfur up to 0.040% and ASTM A 216 allows sulfur up to 0.045%. However, NACE MR0175/ISO 15156, Section 8 says: Conventional forgings with sulfur levels less than 0.025 %, and castings, are not normally considered sensitive to HIC or SOHIC. The above statement means ASTM A 105 forgings are acceptable, if sulfur is limited to 0.025% and hardness to 187 HBW Castings have no additional sulfur limit other than specified in the base spec. (for example: 0.045% for ASTM-A216). The document has reference to many casting and forging grades, but, these two grades are not adequately covered. ASTM A 216 is not covered at all. It would be appreciated if NACE clearly makes mention of these two important materials with limitations if any clearly stated. Would such changes be possible?

    Answer:

    It is outside the scope of the standard to provide information concerning the "limitations" of ASTM A 105 and ASTM A 216 in the specific form you request.

    Many steels, including ASTM A 216, are not individually listed in NACE MR0175/ISO 15156-2. As stated in A.2.1.1 General, Para. 3:

    "The majority of steels that comply with the general requirements of A.2 are not individually listed; however, for convenience, some examples of such steels are listed in Table A.2, Table A.3 and Table A.4." A.2.1.1 deals only with sulfide stress corrosion resistance.

    Where any possible additional restrictions are mentioned (as is the case in Section 8 in relation to HIC/SWC resistance), they refer to any carbon or low alloy steel to which the text might apply.

    This question is in relation to NACE MR0175/ISO 15156-2 Annex A.2.1.1

    Reference: ISO 15156 Maintenance Panel Inquiry #2007-05

    alloy-select can help you determine the NACE MR0175 requirements. alloy select is the only web-based software for materials selection of oil and gas assets and has been developed by the team of experts at Oil & Gas Corrosion. alloy-select has a verify tool that can be used to confirm if a material meets NACE MR0175. To learn more about alloy-select visit alloyselect.com

    Contact our team today for Technical Support in metallurgy, corrosion and NACE MR0175. We can help you confirm HIC resistance.

     

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  • 70. Is 243 Brinell acceptable for carbon steels in accordance with NACE MR0175 / ISO15156-2 Table A.1?
     

    Question:

    I am writing to you to ask for clarification regarding NACE MR0175/ISO 15156-2 We have a part here which was welded and PWHT and the subsequent hardness check revealed a hardness on the weld cap of 243 Brinell. Our engineering department dispositioned this as acceptable in accordance with Table A.1, as Section A.2.1.4 suggests that "Acceptable maximum hardness values for carbon steel, carbon manganese steel, and low-alloy steel welds are given in Table A.1." An independent Competent Body, Lloyds Register, however, has pointed out that Table A.1 mentions "Hardness test locations for welding procedure qualification" utilizing Vickers and Rockwell hardness techniques. Can you please therefore confirm if NACE compliant production welding can be accepted in accordance with this Table, or is it merely for weld procedure qualification.

    Answer:

    Hardness measurements must be performed according to § 7.3.3 using Vickers hardness HV 10 or 5 or Rockwell 15N methods. Brinell hardness method is subject to the acceptance of the equipment user.
    Table A.1 applies to qualification and production hardness values. However since 243 Brinell is above 250 HV or 22 HRC but below the alternate weld cap limit of 275 HV it requires “equipment user” acceptance and also to obey the two other listed requirements in Table A.1.

    This question is in relation to NACE MR0175/ISO 15156-2 Annex A Table A.1

    Reference: ISO 15156 Maintenance Panel Inquiry #2011-05

    Contact our team for technical support.

     

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  • 71. In NACE MR0175, when is a "qualification" required?
     

    Question:

    Could you please define the word "Qualification." In our understanding, qualification is required for new materials that are not listed in Table A.2 of NACE MR0175/ISO 15156-2. We would like you to confirm that our interpretation is correct and if not what is your position?

    Answer:

    Table A.2 of ISO 15156-2 gives examples of materials that can be qualified provided they comply with Paragraph A.2.1. If not listed in Table A.2, materials must be assessed in the terms of the requirements given in Annex A as explained in Paragraph 7 of Part 1. Again it is up to the equipment user to decide if materials need further qualification through testing or field experience as explained in Paragraph 8 of Part 1.

    This question is in relation to NACE MR0175/ISO 15156-2 Annex A Table A.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2009-01

    At Oil & Gas Corrosion we can help you define the qualification requirements to comply with NACE MR0175

     

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  • 72. In NACE MR0175, does the term “hot rolled” only apply to sheet or plate material and cannot be applied to the forming of butt weld fittings?
     

    Question:

    Does the term “hot rolled” referred to in Paragraph A.2.1.2 only apply to sheet or plate material and as such cannot be applied to the forming of butt weld fittings?

    Answer:

    Yes, “hot rolled,” in the view of the Maintenance Panel, does not apply to the forming of butt weld fittings.

    This question is in relation to NACE MR0175/ISO 15156-2 Annex A.2.1.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2004-06

     

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  • 73. Can "as-forged" material be certified to NACE MR0175?
     

    Question:

    Often my company is asked by customers to certify our forgings to NACE MR0175. It is my understanding from them that our competition (including imports), certifies to MR0175 without normalizing and consequently we are pressured to do the same. We have three presses, two are fed by gas-fired furnaces, and one is with induction heaters. The gas heat forgings are typically heated to 2,300 to 2,350°F and forged on a 900T or 3500T open die press in a tooling pot, then still air cooled to ambient. The forgings heated by induction are heated to similar temperatures but only a portion of a bar and the flange end is forged close to shape, then air cooled in still air. Customers can order these forgings in the "as forged" or "normalized" condition per SA105. My question is do we have to normalize the forgings coming from either forging process in order to certify to NACE MR0175? The problem is interpretation of NACE MR0175/ISO 15156-2:2003(E), page 17, Annex A, Paragraph A.2.1.2. The heat-treated condition "hot-rolled" is not clearly understood and competitors with similar processes interpret that if the entire raw material piece prior to forge, let's call it a mult, is taken to 2,300 to 2,350°F prior to forge that this satisfies the "hot-rolled" definition. We have contended that our products need to be subsequently followed with a normalizing cycle after being fully cooled to ambient in order to be certified to NACE and that neither of the forging processes listed above satisfies the definition of "hot-rolled" process.

    Hot-forged material does not meet the intent of NACE MR0175/ISO 15156-2, A.2.1.2a).

    An exception to this statement is given in A.2.1.3a).

    Other hot-forged materials would have to be treated according to one of the five other heat-treatment conditions described in Paragraph A.2.1.2 to comply with this standard.

    As a consequence, ASTM A 105 material is acceptable in the "as-forged" condition not because it is equivalent to a "hot rolled" condition in A.2.1.2, but because it is a permitted exception in A.2.1.3.a.

    This question is in relation to NACE MR0175/ISO 15156-2 Annex A.2.1.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2005-25

    Contact our team of oilfield metallurgists and corrosion consultants to discuss NACE MR0175 and as forged steels.

     

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  • 74. Is ASTM A105 Class 150# flange in the non-normalized is acceptable to NACE MR0175?
     

    Question: Would a forged ASTM A105 Class 150# flange in the non-normalized condition be in accordance with NACE MR0175 and NACE MR0103?

    Answer:

    The ISO 15156 Maintenance Panel can only answer for NACE MR0175/ISO 15156, not for NACE MR0103.
    AS FORGED is not an acceptable condition in A.2.1.2. Both requirements of A.2.1.2. and A.2.1.3 of Part 2 must be fulfilled for ASTM A 105 flanges to meet NACE MR0175/ISO 15156.

    This question is in relation to NACE MR0175/ISO 15156-2 Annex A.2.1.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2009-08

    Our oilfield metallurgist and corrosion consultants in oil and gas can help you comply with NACE MR0175 and NACE MR0103.

     

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    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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  • 75. What are the NACE MR0175 requirements for ASME IX P1 Group 2?
     

    What are the NACE MR0175 requirements for ASME IX P1 group 1 and 2 Material?

    What are the NACE MR0175 requirements for ASME IX P1 Group 1 and 2 materials? from Ivan Gutierrez on Vimeo.

    Ivan Gutierrez discusses the NACE MR0175 requirements for ASME IX P1 Group 1 and 2 materials.

    ASME IX P1 material is listed as acceptable in NACE MR0175, but this does not mean that the general requirements do not apply, i.e. hardness heat treatment, HIC resistance etc. At Oil & Gas Corrosion we can help you confirm material compliance to ANSI/NACE MR0175/ISO 15156. Visit our Frequently Asked Questions sections to access more information on NACE MR0175.

    At Oil & Gas Corrosion we can help you understand and implement the NACE MR0175 requirements for ASME IX materials. Talk to our team today!

     

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    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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    Question: We are trying to identify the MR0175 hardness requirements for P1, Group 2 Carbon Steel (and not A105 or A234) for Pipe, Plate, Fittings, and Pressure vessels. The source of confusion: a) A.2.1.2 identifies a hardness requirement of Rc 22. b) A.2.2.2 states that P-No 1, Group 1 pressure vessel steels are “acceptable.” Theory A supports a requirement of Rc 22 max. Theory B supports that “acceptable” means “acceptable at any hardness,” i.e., there is no maximum hardness requirement for P-No 1, Group 2 material. Which theory is correct? (Note: Our part of interest, a rupture disc holder, seems to fit under both “Pipe, plate and fittings” and “Pressure Vessel.”)

    Answer:

    The Section A.2.2 pertains to the application of the general guidelines to product forms such as pipe, plate and fittings. Section A.2.2.1 states that “Except as modified below, the general requirements of A.2.1 shall apply to all product forms”. There are no exceptions listed in Section A.2.2.2 and Table A.2 that permits exception to the 22 Rockwell C hardness limit. The requirement for 22 Rockwell C maximum remains in effect.

    This question is in relation to NACE MR0175/ISO 15156-2 Annex A.2.1.2 and A.2.2.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2015-01

     

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  • 76. In NACE MR0175, are tubulars with SMYS below 52ksi exempt of hardness testing?
     

    Question:

    Per A.2.1.4 "Tubular products with an SMYS not exceeding 360 MPa (52ksi) and listed in Table A.2 are acceptable in the as-welded condition. For these products, hardness testing of welding procedures may be waived if agreed by the equipment user". Is a correct interpretation that all hardness testing is being waived for tubular products with an SMYS not exceeding 52ksi in the as-welded condition if as agreed by the equipment user?

    Answer:

    No, tubular products listed in Table A.2 with an SMYS not exceeding 360 MPa (52 ksi) are acceptable in the as welded condition. For these products hardness testing OF WELDING PROCEDURES may be waived if agreed by the equipment user.

    This question is in relation to NACE MR0175/ISO 15156-2 Annex A.2.1.4

    Reference: ISO 15156 Maintenance Panel Inquiry #2006-01Q1

     

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  • 77. For NACE MR0175 compliance of carbon steels, what's the maximum hardness after PWHT?
     

    Question:

    A.2.1.4 Welding, Paragraph 6 states: "Carbon steel and low-alloy steel weldments that do not comply with other paragraphs of this subclause shall be stress-relieved at a minimum temperature of 620 °C (1 150 °F) after welding. The maximum weld zone hardness, determined in accordance with 7.3, shall be 250 HV or, subject to the restrictions described in 7.3.3, 22 HRC." This particular paragraph does not refer to Table A.1 (Maximum acceptable hardness values for carbon steel, carbon-manganese steel and low-alloy steel welds), which states that weld cap hardness can be 275 HV with limitations. Could NACE please clarify if Table A.1 should or should not be applicable for stress-relieved weldments. Which hardness value 250 HV or 275 HV shall be applicable for weld cap hardness of stress-relieved weldments?

    Answer

    Table A.1 gives maximum acceptable values for carbon steel, carbon-manganese steel and low alloy steel weldments. It is applicable to welds whether they have been post weld heat treated or not.

    This question is in relation to NACE MR0175/ISO 15156-2 Annex A.2.1.4

    Reference: ISO 15156 Maintenance Panel Inquiry #2011-01

     

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  • 78. Weldment with Nickel greater than 1%, does NACE MR0175 / ISO 15156-2 subclause A.2.1.4 say they are not acceptable?
     

     

    Question: ISO 15156-2 subclause A2.1.4 Welding has the following two paragraphs: "Carbon steel and low-alloy steel weldments that do not comply with other paragraphs of this subclause shall be stress-relieved at a minimum temperature of 620 °C (1150 °F) after welding. The maximum weld zone hardness, determined in accordance with 7.3, shall be 250 HV or, subject to the restrictions described in 7.3.3, 22 HRC". "Welding consumables and procedures that produce a deposit containing more than 1 % mass fraction nickel are acceptable after successful weld SSC qualification by testing in accordance with Annex B". Based on this, I interpret the requirements as follows: If there are weldments with Ni contents greater than 1% mass fraction, they can be accepted if the weld procedures are successfully tested to SSC qualification in accordance with Annex B. Alternately, weldments with Ni contents greater than 1% mass fraction shall be acceptable if stress-relieved at a minimum temperature of 620 °C (1150 °F) after welding. The maximum weld zone hardness, shall be 250HV or 22 HRC in that case.Please can you confirm the interpretation.

    Answer:

    The intent of the next to last paragraph in A.2.1.4 (15156-2, Annex A) dealing with the 620C (1150F) SR option does not negate the requirement in the following paragraph which requires SSC qualification testing regardless of SR if the weld deposit is >1% Ni.

    This question is in relation to NACE MR0175/ISO 15156-2 Annex A.2.1.4

    Reference: ISO 15156 Maintenance Panel Inquiry #2013-07

    At Oil & Gas Corrosion we see many enquiries related to stress relief and nickel content in weldments. Weldments with Ni contents greater than 1% mass fraction shall be qualified.

     

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  • 79. NACE MR0175 and surface treatments to prevent SSC
     

    Question: ANSI/NACE MR0175/ISO 15156-2, Section A.2.1.5, Surface Treatments, Overlays, Plating, Coatings, Linings, etc. This section states that metallic coatings, such as electroless nickel plating, are not acceptable for preventing SSC. It was my understanding that the qualification of a plated part was dependent on the base metal. If the base metal is in conformance with MR0175 then the part can be qualified regardless of what plating or coating may be applied. Is my understanding correct?

    Answer:

    The application and use of metallic plating that does not affect the ISO 15156 compliant base material is not prohibited. No metallic platings are listed as acceptable or unacceptable in ISO 15156 but the use of any surface treatments to prevent SSC is not acceptable.

    This question is in relation to NACE MR0175/ISO 15156-2 Annex A.2.1.5

    Reference: ISO 15156 Maintenance Panel Inquiry #2011-13

     

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    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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  • 80. In NACE MR0175, are all bolts required to comply, even external flange bolts?
     

    UPDATE 2017-12-22

    ANSI / NACE MR0175 / ISO 15156 has been updated with a Technical Circular which is relevant to external bolts. We recommend to follow this link related to part 2 A.2.2.4 Bolting and Fasteners:

    https://oilandgascorrosion.com/nace-mr0175-iso-15156-technical-circulars-for-part-1-and-2-published-2017-12-22/

    Below there is some further information for reference.

    Bolt compliance to NACE MR0175 can sometimes cause confusion, for example flange bolts are not in direct contact with the transport fluids, however a leak may expose them to H2S. NACE MR0175 / ISO 15156 -2 section A.2.2.4 addresses this matter.

    In 2011 an inquiry was sent to the maintenance panel as shown below, and the answer reinforces the fact that the equipment user is responsible for NACE MR0175 compliance.

    Question:

    I have a query in respect to the identification of the sour environment for deciding whether a bolting alloy shall conform to the general requirements of A.2.1 as reuired by A.2.2.4, where the bolting material is denied direct atmosphere exposure. An example best illustrates my question. In a pressure containing piping or vessel, it is clear that the partial pressure of H2S within the pressure containment determines whether the piping or vessel is exposed to sour service. Flange bolting is located ourside the vessel and the piping and flange protection systems are seldom pressure containing enclosures. If a leak occurs the partial pressure of H2S will be reduced according to the ratio of the external pressure (typically 1 atm or 100 kPa) to the total pressure internal to the vessel. My question then is whether it is the partial pressure of H2S in the external environment or the partial pressure of H2S in the internal environment that is used to determine whether the bolting material is in sour service.

    Answer

    The equipment user is responsible for defining the intended service environment and selecting materials in accordance with this standard.

    This question is in relation to NACE MR0175/ISO 15156-2 Annex A.2.1 and A.2.2.4

    Reference: ISO 15156 Maintenance Panel Inquiry #2011-12

    At Oil & Gas Corrosion we help equipment users, operators and product manufacturers to comply with NACE MR0175 including bolt material selection.

     

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  • 81. For NACE MR0175 compliant products, is Carburizing an acceptable surface treatment process?
     

    Q1: For NACE MR0175 compliant products, is Carburizing an acceptable surface treatment process?

    A1 Carburizing is not currently permitted in ISO 15156 except in conjunction with the permitted exclusions in Table 1 of ISO 15156-2. These exclusions are associated with specific equipment that is loaded in compression and equipment that is outside the scope of ISO 15156.

    Q2: If Carburizing is not considered the same as Nitriding in paragraph A. 2.1.5, is it acceptable to have carburized surface treatment (where the surface hardness will be well over HRC 22 hardness) but the core to meet the maximum average hardness of 22 HRC?

    A2: Carburizing is not permitted regardless of core hardness except as noted in Q1.

    Q3: If Carburizing is acceptable surface treatment method, can the max hardness (HRC 22) and Nickel content (max 1%) of the core of carburized part be allowed to be higher than what NACE MR0175 allows?

    A3: Not applicable.

    This question is in relation to NACE MR0175/ISO 15156-3 Annex A.1.5.1

    Reference: ISO 15156 Maintenance Panel Inquiry #2013-04

     

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  • 82. Does NACE MR0175 accepts 26HRC for temporary pipework?
     

    Question:

    We need a clarification on MR0175/ISO 15156 Part 2, Annex A. We are a manufacturer of temporary pipe work, flowlines, etc., for sour gas service in well testing and process use in a surface application. As such we believe Paragraphs A.2.1 through A.2.4 and Table A.1 with a hardness limit of 22 HRC are applicable in these circumstances. However, pipe suppliers in this region tell us that 26 HRC is acceptable in such applications. I believe the 26 HRC limit is only applicable to material used in a downhole application as in Paragraph A.2.2.3, etc. (i.e., not a surface application) and that this is in error in terms of our usage.

    Answer:

    ISO 15156-2, A.2.2.1 indicates that carbon and low alloy steels for use in any product form must comply with the requirements of A.2.1 which include the hardness requirement of maximum 22 HRC for the parent material. Exceptions to this rule are named specifically in other paragraphs of Annex A.
    Welds in such materials shall comply with the requirements of A.2.1.4 that also refers to Table A.1 that sets hardness requirements for welds.
    Sub-clause A.2.2.2 provides examples of materials that can comply with A.2.1, including some examples of tubular products in Table A.2.
    Sub-clause A.2.2.3 addresses downhole components only.
    The standard allows materials, such as AISI 4130, to be qualified at higher hardness than 22 HRC for possible use as pipe in sour service by laboratory testing in accordance with Annex B and Table B.1 or on the basis of field experience as described in ISO 15156-1, 8.2. Welds must be shown to comply with the requirements of Paragraph 7.3.3.4.

    This question is in relation to NACE MR0175/ISO 15156-2 Annex A.2.2.1, A.2.2.2 and A.2.2.3

    Reference: ISO 15156 Maintenance Panel Inquiry #2005-23

     

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  • 83. What are the NACE MR0175 requirements for API 5CT C110?
     

    Question: This question regards to mild sour service conditions and where C110 grade steel would fall into the standard (it is my understanding is that it is currently going to ballot to be added expressly to MR0175/ISO15156).By section A.2.2.3.2 C110 is qualified for any SSC region at greater than 150°F (65 C) , yet, section A.4 seems to indicate that C110 would be fine at any temperature in Region 1. The flow chart in B.2.1 describes the process and the question is whether we can select any steel that is listed in Annex A (includes steels in A.2, A.3 and A.4) for Region 1?

    Answer:

    The Table A.3 with the temperature constraints is part of Section A.2.2.3 for Downhole casing, tubing and tubular components; the temperature restrictions of this Table apply to Section A.2.2.3.2. The user of the document may use A.4 to qualify those steels that may not comply with Sections A.2 or A.3 using the UT test as specified in Section B.1 for each test batch. Figure 1 addresses pH and H2S partial pressure without the limitations that are associated with minimum temperatures for higher strength steels.

    This question is in relation to NACE MR0175/ISO 15156-2 Annex A.2.2.3.2 and A.4

    Reference: ISO 15156 Maintenance Panel Inquiry #2015-07

    UPDATE: NACE MR0175 / ISO 15156 -2 Technical Circular 1 modifies Table A.3. follow this link for more information:

    https://oilandgascorrosion.com/nace-mr0175-iso-15156-technical-circulars-for-part-1-and-2-published-2017-12-22/

     

    If you need additional support for API 5CT materials selection talk to one of our oilfield metallurgists.

     

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  • 84. In NACE MR0175, is ductile iron ASTM A 536 acceptable for pressure-containing parts?
     

    Question:

    In NACE MR0175/ISO 15156 Part 2, Paragraph A.2.4, ductile iron ASTM A 536 is listed in Table A.5 as acceptable materials for drillable packer components for sour service. However, it is not mentioned in Paragraph A.2.4.1. Can we use this material for pressure-containing parts, i.e., valve stems?

    Answer:

    No, ductile iron ASTM A 536 is not listed in A.2.4.1 and may not be used for pressure-containing parts.

    This question is in relation to NACE MR0175/ISO 15156-2 Annex A.2.4.1 and A.5

    Reference: ISO 15156 Maintenance Panel Inquiry #2004-20

    Talk to our team to discuss the NACE MR0175 requirements for cast irons.

     

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  • 85. For HIC test, What is the NACE MR0175 / TM0284 acceptance criteria?
     

    Question: For HIC test, NACE MR0175/ISO 15156-2, Table B.3 is not clear regarding the acceptance criteria to be taken into account. We usually understood that "CLR, CTR, CSR" to be taken into account is the average of the values measured from one test specimen as defined in NACE Standard TM0284, Paragraph 4.2.1. What is your position?

    Answer:

    ISO 15156-2, B.5, Paragraph 3 makes clear that where no requirement is given NACE TM0284 shall be followed.

    This question is in relation to NACE MR0175/ISO 15156-2 Annex B Table B.3

    Reference: ISO 15156 Maintenance Panel Inquiry #2005-26Q2

    The team at Oil and Gas Corrosion Ltd has prepared checklists that will help you make sure your material complies with NACE MR0175, visit the live and fully functional checklist for:

    ASTM A516 Gr 70 NACE MR0175

    A new revision of NACE TM0284 was issued in 2016; make sure you read our article on the main changes of NACE TM0284 2016: https://oilandgascorrosion.com/tm0284-2016/

    UPDATE 2018-06-04: A recent Technical Circular brings relevant updates on NACE MR0175 regarding the HIC testing acceptance criteria: https://oilandgascorrosion.com/nace-mr0175-iso-15156-technical-circulars-for-part-2-and-3-published-2018-06-01/

    We are here to help you, talk to our team today!

     

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  • 86. What is NACE MR0175 intent when it comes to H2S partial pressure? operating or design pressure to be used in the calculations?
     

     

    The partial pressure of H2S (ppH2S ) is used throughout ANSI/NACE MR0175/ISO 15156 to set the production environment limits for carbon steels, low alloy steels and corrosion resistant alloys. However, NACE MR0175 does not specify if the user should consider operation pressure, design pressure or an intermediate value. So, what is NACE MR0175 intent when it comes to H2S partial pressure? operating or design pressure to be used in the calculations? Here, Oil & Gas Corrosion addresses these questions.

    First, we have to define the partial pressure of H2S (ppH2S ) which is calculated as:

                     ppH2S = system total absolute pressure x mol fraction of H2S present

    Is the system total absolute pressure the design or the operating pressure? This is one of the most  frequently asked questions and this video clarifies if design or operating pressure should be used.

    partial pressure of H2S, design or operating conditions? from Ivan Gutierrez on Vimeo.

     

    At Oil & Gas Corrosion we help clients to determine the partial pressure of H2S. We have the expertise to help you decide if you should use the operating or design pressure. We do this by evaluating the production conditions (pressure, temperature, produced water etc.), the design and evaluating the risks and consequences. We are here to help you with sour service materials selection and partial pressure calculations.

    Talk to our team to today!

     

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    This video makes reference to an inquiry sent to the NACE MR0175 maintenance panel. The inquiry is below:

    QUESTION: What is NACE's intent when it comes to H2S partial pressure? i.e., when calculating the H2S partial pressure per Annex C.1 and C.2 in NACE MR0175/ISO 15156-2, should the operating or design pressure be used in the calculations? I believe operating pressure should be used. Could you please confirm?

    ANSWER:

    15156-1 Para 6.1 states that the user shall define the service conditions including unintended exposures (e.g., resulting from failure of primary containment). These service conditions become the basis for calculating H2S partial pressure. It is up to the user to decide whether to use operating or design pressure for partial pressure calculations.

    Reference: ISO 15156 MP Inquiry #2009-21 (NACE MR0175 Part 2 Annex C)

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  • 87. According to NACE MR0175, what is a Corrosion Resistant Alloy?
     

    What is a Corrosion Resistant Alloy? 

    Question: I need your help with the definition of CRAs in Part 3 of MR0175/ISO 15156. The "corrosion-resistant alloys" is very general and does not specify whether or not the definition includes the Fe-based alloys or not. More than that, the term CRA is used together with "other alloys" making it even more confusing.

    Answer:

    NACE MR0175/ISO 15156-1, Paragraph 3.6 contains a definition of "corrosion-resistant alloy" (CRA). It reads: "alloy intended to be resistant to general and localized corrosion of oilfield environments that are corrosive to carbon steel." This is taken from EFC 17. "Other Alloys" are those not covered by the definitions of carbon steel or CRA. For example, copper is not considered resistant to general corrosion but is considered in NACE MR0175/ISO 15156-3.

    This question is in relation to NACE MR0175/ISO 15156-3

    Reference: ISO 15156 Maintenance Panel Inquiry #2004-12

     

    With a wealth of experience in the oil and gas industry, we provide independent materials and corrosion consultancy to help companies reduce risk, save money and apply best practice in their oil and gas businesses.

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  • 88. in NACE MR0175, what does “Exposure temperature” mean? Design or operating Temperature?
     

     

    NACE MR0175/ISO 15156-3: 2009(E), What does “Exposure temperature” mean? Design or operating Temperature?

    “The equipment user shall define the exposure temperature”

    This question is in relation to NACE MR0175/ISO 15156-3 Clause 5

    Reference: ISO 15156 Maintenance Panel Inquiry #2015-02 Q1

    At Oil & Gas Corrosion we can help you define the exposure temperature and comply with NACE MR0175.

     

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  • 89. What is NACE MR0175 test position for cold worked austenitic stainless steels (e.g. 304, 316 and 316L)?
     

    Question: Our company has understood that NACE MR0175/ISO 15156, Table A.2 required the maximum specified hardness for austenitic stainless steels be satisfied at any location on bar stock (e.g., at locations considered significant by the user). Since cold-finished bars frequently have surface hardness values above the maximum specified in MR0175, we have declined to certify these products as compliant to the specification. We appear to be in the minority, or perhaps the only stainless bar producer that interprets the standard in this way. We routinely find competitors' cold-finished stainless bar in the marketplace certified to MR0175 based on a mid-radius hardness even though the surface hardness is above the maximum permitted in the standard. We realize this is a long-standing issue, but would like to clarify the hardness requirements of the Table A.2. We understand the logic in requiring the material meet a hardness maximum at any location (e.g., surface) in order to provide a predictable level of stress corrosion cracking resistance. Yet the standard does not clearly state, for example, that meeting surface hardness is a requirement. Please clarify the hardness requirements of MR0175 to allow all stainless bar producers to provide a uniform product to this standard.

    Answer:

    NACE cannot provide assistance in specifying where to take hardness impressions and readings for this alloy or for any other alloy. This is because NACE MR0175/ISO 15156 is not a quality assurance document. It is the responsibility of the alloy supplier to meet the hardness requirements and metallurgical requirements of the austenitic stainless steels in Table A.2.

    This question is in relation to NACE MR0175/ISO 15156-3 Clause 6.2.1

    Reference: ISO 15156 Maintenance Panel Inquiry #2003-06

    At Oil & Gas Corrosion we help clients to implement the requirements of NACE MR0175. If you need assistance with the NACE MR0175 compliance of austenitic stainless steels (304, 316, 316L etc) we can help you.

     

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  • 90. In NACE MR0175, are austenitic and duplex stainless steels acceptable "as welded"? or do they need PWHT?
     

    Question:

    For the cast austenitic and duplex stainless steels there is no specific mention of a requirement for post weld heat treatment in Part 3 that discusses welding of these alloys. However, there is a statement in the application of these alloys that they are only acceptable in the solution annealed and quench condition. In my opinion, the as welded condition does not meet the intent of being solution annealed and quenched. So can these alloys be used in the as welded condition?

    Answer:

    These alloys can be used in the as welded condition provided they meet the requirements of Paragraph 6.2 of ISO 15156-3 and the corresponding Tables in Annex A. In particular Paragraph 6.2.2 indicates that welding PQRs shall include documented evidence of satisfactory cracking resistance.

    This question is in relation to NACE MR0175/ISO 15156-3 Clause 6.2.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2009-03

    Talk to us to discuss your WPQR/WPS and NACE MR0175 compliance.

     

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  • 91. According to NACE MR0175, What are the hardness requirements and what hardness method should be used?
     

    What are the hardness requirements according to NACE MR0175? Is 22HRC enough to meet NACE MR0175? What method should be used to measure hardness?

     

    ⊗ 22HRC is not the only NACE MR0175 requirement (see this link).

    ⊗ 22HRC applies for some carbon and low alloy steels, but 22HRC is not the hardness limit for all materials.

    ⊗ The conversion of hardness readings to and from other scales is material dependent; there are hardness conversion tables such as ASTM E140, ISO 18265 . As per NACE MR0175, the user may establish the required conversion tables.

    At Oil & Gas Corrosion we can help you confirm the NACE MR0175 including hardness, heat treatment and chemical composition. Don't risk making a mistake, Talk to our team today!

     

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    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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    alloy select is a web-based software for materials selection of oil and gas assets and has been developed by the team of experts at Oil & Gas Corrosion. alloy-select can help you determine the NACE MR0175 requirements.  To learn more about alloy-select visit alloyselect.com or use our webchat today, we are here to help.

    Specifically for CA6NM and F6NM, the hardness requirements are listed in NACE MR0175 part 3, clause A.6. The hardness limits are listed in Hardness Rockwell scale C (HRC). However, for welding purposes HV10 or HV5 is required and currently there is no conversion from HRC to HV10 in the published references. The conversion must be agreed between manufacturer and equipment user.

    Question:

    Per A.6.3 "The hardness of the HAZ after welding shall not exceed the maximum hardness allowed for the base metal, and the hardness of the weld metal shall not exceed the maximum hardness limit of the respective alloy used for the welding consumable." Per Table A.23 note (b) "Low-carbon, Martensitic stainless steels either cast J91540 (CA6NM) or wrought S42400 or S41500 (F6NM) shall have 23 HRC maximum hardness..." Per 6.2.2.2.2 "Hardness testing for welding procedure qualification shall be carried out using Vickers HV 10 or HV 5 methods in accordance with ISO 6507-1 or the Rockwell 15N method in accordance with ISO 6508-1. The use of other methods shall require explicit user approval." However, neither a Vickers nor Rockwell 15N acceptance criteria is specified for Martensitic Stainless Steels. Furthermore, ASTM E140 does not provide a hardness conversion for Martensitic Stainless Steels. Thus, there is neither a Vickers nor Rockwell 15N acceptance criteria. Is a correct interpretation that the acceptable hardness test method for qualification of Martensitic Stainless Steels is the Rockwell C Method, regardless of the applied stress, and without the need for explicit user approval?

    Answer:

    No, ISO 15156-3, 6.2.1, Para. 2 states "The conversion of hardness readings to and from other scales is material dependent; the user may establish the required conversion tables".

    This question is in relation to NACE MR0175/ISO 15156-3 Clause 6.2.2.2.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2006-01Q3

    There is an API committee currently working in preparing a conversion table for martensitic stainless steel, duplex stainless steels and nickel alloys.

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  • 92. In NACE MR0175, is nitro-carburizing allowed?
     

    Question:

    Will "Nitro-Carburizing" be allowed surface treatment with the same status of "Nitriding"? If it is allowed, would the NACE requirement be the same as Nitriding or it would be different?

    Answer:

    As ISO 15156 is written today, the acceptable surface treatment has been defined solely as nitriding below the lower critical temperature.
    Additional response to query submitter: We believe that you have identified an area where our standard ISO 15156 does not accurately define what has been accepted practice in the Oil & Gas Industry.
    It has been common practice to use salt bath, liquid or ion nitriding including nitrocarburizing and carbonitriding for a wide variety of applications.
    The two key elements that have been constant through the years are that the maximum case depth has been defined as 0.15 mm (0.006”) and the process temperature is below the temperature where any new transformation products are formed; this is the lower critical temperature for the alloy being processed.
    The only application problems that we are aware of are when the nitriding (and related) processes are applied to areas where the local yield strength is exceeded; in these areas the plastic deformation has resulted in local breaks or cracks through the hardened surface due to the reduced ductility that is associated with the higher hardness. The MP will propose a ballot to clarify the description of acceptable processes.
    Note that this ballot will need to be successful before this is an approved process listed in ISO 15156.

    This question is in relation to NACE MR0175/ISO 15156-3 Annex A.1.5.1

    Reference: ISO 15156 Maintenance Panel Inquiry #2013-08

    Contact us to discuss your surface treatment requirements and NACE MR0175 compliance.

     

    With a wealth of experience in the oil and gas industry, we provide independent materials and corrosion consultancy to help companies reduce risk, save money and apply best practice in their oil and gas businesses.

    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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  • 93. NACE MR0175 requirements for Gr. 660 flange bolting materials
     

    Question 1:

    Does NACE MR0175/ISO 15156-2, Paragraph A.2.2.4 apply to Gr. 660 flange bolting materials or only to carbon and low alloy steel bolting materials in Part 2?

    Answer:

    Paragraph A.2.2.4 only applies to materials in Part 2. See also response to MP Inquiry #2005-09Q2 posted under ISO 15156-3, Table A.26.

    It is assumed in Table A.2 that this is a mixed-phase environment with both a gas phase and a liquid phase. This is always true throughout the document. The operator is responsible for determining the service conditions, including chloride content (see ISO 15156-1, 6.1) and the ISO Maintenance Panel cannot provide advice. As mentioned in ISO 15156-3, A.1.3, Paragraph 2: “The tables show the application limits with respect to temperature, pH2S, Cl, pH, S. These limits apply collectively.” However, if, as an equipment user, you feel that ISO 15156-3, Table A.2 does not address your expected field conditions you have the freedom to test materials under alternative environmental limits and to use the outcome of successful tests to justify the use of a material outside the limits set in the standard. (See ISO 15156-3, 6.1, Para. 5.)

    Question 2:
    Does NACE MR0175/ISO 15156-3 Table A.26 apply to Gr. 660 material used in subsea bolting applications external to the production wellbore environment when indirectly heated above 150°F?
    Answer

    Table A.26 does not apply to Grade 660 material used in subsea bolting applications external to the production wellbore environment

    This question is in relation to NACE MR0175/ISO 15156-2 Annex A.2.2.4

    Reference: ISO 15156 Maintenance Panel Inquiry #2005-09Q1 and Q2

    At Oil & Gas Corrosion we help clients define bolt requirements to comply with NACE MR0175 including subsea bolting.

     

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  • 94. What are the NACE MR0175 traceability requirements?
     

    Question:

    Following ISO 15156-3 Section 7.2 Marking, labeling and documentation, it is indicated that material complying with ISO 15156 shall be made traceable. This section confirms that suitable documentation can ensure acceptable traceability without listing the documentation required. Could you please clarify what are the documents required to ensure acceptable traceability of material complying with ISO 15156?

    Answer:

    Required documents to ensure acceptable traceability shall be agreed with the equipment user.

    This question is in relation to NACE MR0175/ISO 15156-3 Clause 7.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2014-10

     

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    At Oil & Gas Corrosion we frequently receive questions about the certification of materials and equipment to NACE MR0175. This is why we prepared a short webinar on the basics of certification to NACE MR0175 and how we are helping clients to solve some of these challenges.

    Certification of materials and equipment to NACE MR0175 from Ivan Gutierrez on Vimeo.

     

    Reference: ISO 15156 Maintenance Panel Inquiry 2006-13.

    Certification can be a challenging topic and we have helped clients answer some of these questions:

    • Who is responsible for certification?

    • Our material is certified to NACE MR0175 2009 and our client needs certificates to 2015, what can we do?

    • How can a raw material (steel) manufacturer certify a material if they do not know the final application and its conditions.

    • Our material does not state “Certified to NACE MR0175”, can it be used in sour service?

    At Oil & Gas Corrosion we can help you resolve this and more certification issues. Talk to our team today!

     

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    Question:

    Is it the intent of NACE MR0175/ISO 15156-2 that material manufacturers state on the Material Test Certificates that material conforms to the NACE standard even though no operating criteria are known?

    Answer:

    Certification requirements are outside the scope of the standard and there are no stipulations concerning certification in NACE MR0175/ISO 15156.

    The compliance with the NACE/ISO standard of a material for use in H2S-containing environments in oil and gas can only be assessed for the material in its final product form and this may differ metallurgically from that of the material supplied by the materials manufacturer. In addition, compliance with the standard also depends on the cracking mechanisms that have to be considered.

    NACE MR0175/ISO 15156-2, Clause 9, Annex E (Informative) and NACE MR0175/ISO 15156-3, 7.2, Annex C (Informative) make some suggestions on how materials manufacturers and other suppliers might mark their materials to indicate the evaluation (testing) that they have carried out.

    This question is in relation to NACE MR0175/ISO 15156 / Certification and Compliance

     

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  • 95. What does NACE MR0175 require from dissimilar welds without filler?
     

    Question:

    My employer manufactures pressure sensing devices that have a very small sensing diaphragm welded to a threaded port. I am hoping you can provide some clarification regarding welding of dissimilar metals. I am employing the material hardness limits for specific materials from Annex A of ISO 15156-3 in conjunction with the weld survey locations specified in 7.3.3.3 of ISO 15156-2. I believe the hardness requirements are clearly interpreted if welding dissimilar metals by use of a third weld-filler metal. Hardness requirements can be clearly applied to each of the weld survey locations for all three involved parent materials. However, I do not know how to apply the hardness requirements when two materials are welded directly together without the use of a third weld-filler metal. 1. If the two materials have different hardness limits, what is the hardness requirement for the weld survey locations within the weld metal region (non parent material nor HAZ regions)? 2. Is the hardness limit governed by the higher of the two material limits or the lower of the two? 3. Can you tell me where I can find clarification in these standards or where I can direct my question? 4. On an unrelated note, I would like to suggest a minor improvement to table A.1 of ISO 15156-3 Annex A. In Table A.6, Note-B defines the table applicable to “…diaphragms, pressure measuring devices and pressure seals.” Table A.1 would be improved if “A.6” was specified in the first column (Austenitic stainless steel) for the row designated for “Diaphragms, pressure measuring devices and pressure seals”.

    Answer:

    1. The hardness requirements for each material shall be met for both the base metal and HAZ. The standard does not specify requirements for the fusion line hardness between two dissimilar metals with different maximum hardness requirements. Qualification by successful laboratory testing in accordance with Annex B of ISO 15156-3 is required. Qualification based on satisfactory field experience is also acceptable. Such qualification shall comply with ISO 15156-1.
    2. See answer to point 1
    3. See answer to point 1.
    4. This is an editorial improvement and this will be changed.

    This question is in relation to NACE MR0175/ISO 15156-3 Annex A

    Reference: ISO 15156 Maintenance Panel Inquiry #2014-04

    Talk to our team of experts in welding and NACE MR0175

     

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  • 96. Flame spraying, is it allowed in NACE MR0175?
     

    Question:

    We have some 316 stainless steel housings with a large through bore machined. Inadvertently this bore was machined oversize. We would like to flame spray build up the surface with 316 or 316L stainless material and remachine to size. As we understand the standard, 316 and 316L stainless are both included in a lengthy list of materials accepted for direct exposure to sour gas. As we intend to apply stainless to stainless for the purpose of remachining to dimension and not as a corrosion-inhibiting coating, would this process be acceptable and compliant with the NACE Standard MR0175/ISO 15156?

    Answer:

    1.0 Flame spraying as a coating for corrosion resistance over a base material that is resistant to sulfide stress cracking is acceptable within the requirements of NACE MR0175/ISO15156 Part 2 Paragraph A.2.1.5 when applied over carbon steels and of Part 3 Paragraph A.1.5.1. In the case of your inquiry, the 316 or 316L base materials are acceptable coating substrates if they conform to the metallurgical requirements of Part 3 Table A.2 and are used within the environmental restrictions of this table for any equipment.
    2.0 If this application of flame spray is for the replacement of material that will be load bearing of tensile stresses, then the inquiry is not currently addressed by NACE MR0175/ISO15156. NACE/ISO have not been balloted with data to demonstrate that the 316 SS or 316L SS deposited flame spray coating has the same cracking resistance as the materials referenced in Part 3 Table A.2, which are assumed to be in the cast or wrought conditions.

    This question is in relation to NACE MR0175/ISO 15156-3 Annex A.1.5.1

    Reference: ISO 15156 Maintenance Panel Inquiry #2005-01

     

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  • 97. 22HRC for NACE MR0175? is it before or after shaping, forming, cold reducing, expansion?
     

    Question:

    As per Technical Circular 3 of ISO 15156 Part 3, Table A.2, parent material selected for our site condition complies with note (a) of table A.2. This parent material will comply with requirement of maximum 22HRC. It is not mentioned in note (a) if this maximum hardness requirement should be verified before or after shaping, forming, cold reducing, tension, expansion, etc… Could you please clarify?

    Answer:

    Hardness requirement of maximum 22 HRC shall be verified after cold working. Note that cold working intended to enhance the mechanical properties is prohibited.

    This question is in relation to NACE MR0175/ISO 15156-3 Table A.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2014-11

     

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  • 98. NACE MR0175, which Temperature has to be considered; Operating or Design Temperature?
     

    Question:

    NACE MR0175/ISO 15156-3: 2009(E) Table A2 & NACE MR0175/ISO 15156-3: 2009/Cir.2:2013(E), Table A2 Which Temperature has to be considered against Colum no:2 of Table A.2, Operating or Design Teperature?

    Answer:

    “The temperature column in Table A.2 (and for all other tables) defines the maximum exposure temperature in combination with the limits for partial pressure of H2S, chloride and pH. The equipment user shall define the exposure temperature. The equipment manufacturer may define an operating temperature range or safe use maximum temperature for a specific product.”

    This question is in relation to NACE MR0175/ISO 15156-3 Table A.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2015-02 Q2 & Q3

    At Oil & Gas Corrosion we see many enquiries related to the exposure temperature. We have the expertise to help you decide if you should use the operating or design temperature. We do this by evaluating the production conditions (pressure, temperature, produced water etc) and evaluating the risks and consequences.

     

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  • 99. Refinery sour gas treatment units , what are the NACE MR0175 limits?
     

    Question:

    We are now in the detailed engineering design phase of a sour gas refinery, and we have implemented NACE MR0175/ISO 15156 for design purposes. NaCl (sodium chloride) will come to the refinery through three-phase flow pipeline from offshore, after liquid separation in slug catcher; then the sour gas will go to gas treatment units for further processing. Table A.2 refers to chloride content in aqueous solution as mg/L; my question is in sour gas treatment units in which we use austenitic stainless steel, what are the criteria for the limitation of application of austenitic stainless steel? My idea is we have to comply with the first row of Table A.2. There is no means to identify the chloride content in the gas stream.

    Answer:

    It is assumed in Table A.2 that this is a mixed-phase environment with both a gas phase and a liquid phase. This is always true throughout the document.
    The operator is responsible for determining the service conditions, including chloride content (see ISO 15156-1, 6.1) and the ISO Maintenance Panel cannot provide advice. As mentioned in ISO 15156-3, A.1.3, Paragraph 2: “The tables show the application limits with respect to temperature, pH2S, Cl, pH, S. These limits apply collectively.”
    However, if, as an equipment user, you feel that ISO 15156-3, Table A.2 does not address your expected field conditions you have the freedom to test materials under alternative environmental limits and to use the outcome of successful tests to justify the use of a material outside the limits set in the standard. (See ISO 15156-3, 6.1, Para. 5.)

    This question is in relation to NACE MR0175/ISO 15156-3 Table A.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2004-21

    The information of this inquiry needs to be reviewed in light of the requirements of NACE MR0103. Talk to us to discuss sour service requirements for upstream and downstream applications.

     

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  • 100. SS316L in thermowell applications and NACE MR0175
     

    Question:

    I have a technical query related MR0175/ISO 15156 and the use of 316 stainless steel for sour service application. This standard imposes restrictions on the use of 316 SS in environments operating above 60°C. My question is can 316 SS be used above 60°C for non-stressed vessel internals or for items such as thermowells located into sour lines or vessels? I ask this because I note that the standard need not be applied to parts loaded in compression (Table 1). The implication may be that parts have to be stressed for SCC to be an issue. As a similar situation to vessel internals and thermowells, please could you advise on the use of 316 stainless steel for valve internals in a sour application, operating above 60°C. Of particular interest is the use of solid 316 SS balls for ball valves.

    Answer:

    1.0 The scope of NACE MR0175/ISO 15156 Part 3, Paragraph 1, Sentence 1 defines the applicability of the standard. The standard need not be applied for equipment not covered by this sentence. In addition, in Table 1, parts loaded in compression are included among those considered to be "permitted exclusions." SCC requires a tensile stress (applied and/or residual) to occur. There is no provision for any of the alloys in the standard for a threshold tensile stress below which failure cannot occur.
    2.0 The Maintenance Panel cannot analyze the design of equipment. It is up to the manufacturer and equipment user to agree whether or not the scope or any of the listed exclusions in Table 1 apply for a given design.

    This question is in relation to NACE MR0175/ISO 15156-3 Table A.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2005-03

     

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  • 101. What is the NACE MR0175 test location for round bar stock 304/316 SS?
     

    Question:

    For round bar stock 304/316 SS material, does the NACE MR0175 Rockwell C 22 max hardness requirement refer to the hardness anywhere on the raw material or does it refer to the hardness measured at mid-radius, which is the location where ASTM standards require the hardness measurement to be made? For 304/316 austenitic stainless steel MR0175 indicates that the hardness must be Rockwell C 22 max as long as the material was not hardened to enhance mechanical properties. The hardness on 304/316 SS round bar typically varies with radial position. The material typically has the highest hardness readings at the outer surface and lowest in the center. ASTM standards define hardness measurements for bar stock to be taken at mid-radius. In purchasing raw material, the hardness readings reported are at mid-radius.

    Answer

    The Maintenance Panel cannot comment on the hardness test locations specified in ASTM standards.
    These materials, when used for sour service, must comply with all the requirements of NACE MR0175/ISO 15156-3, Table A.2. The definition of the hardness testing location is outside the scope of the standard, but hardness requirements must be met regardless of the chosen test location.

    This question is in relation to NACE MR0175/ISO 15156-3 Table A.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2006-05

    At Oil & Gas Corrosion help clients meet NACE MR0175 requirements including hardness values (and testing location).

     

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  • 102. NACE MR0175 allow the use of Alloys S20100, S20200 and S20500?
     

    Question:

    Clause A.2.1 lists the required elements and ranges for austenitic stainless steels. Alloys S20100, S20200 and S20500 listed in table D1 do not meet the specified limits nor are they covered by individual approval. Is there any reason for these materials being listed in the aforementioned table?

    Answer:

    These alloys do not meet the requirements of A.2 so they are not covered by the ISO 15156-3 austenitic stainless steel limit tables. Annex D as stated in the standard is for information only. It is not a list of approved materials.

    This question is in relation to NACE MR0175/ISO 15156-3 Table A.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2009-19

     

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  • 103. SS 304L for compressor pipeline and NACE MR0175
     

    Question:

    I have an application where I am supplying a pipeline from a gas compressor to a turbine generator. The pipe is 10 in. in diameter and contains natural gas with H2S. The H2S concentration is 250 ppm by volume. The gas is pressurized to 475 psi @152°F. I would like to know what table from Annex A this pipe would fall under. The material I would like to use is 304L SS, which satisfies the requirements in A.2. I would appreciate any guidance you can provide with this subject.

    1a) NACE MR0175/ISO 15156-3, Table A.6 provides environmental and materials limits for austenitic stainless steels used in compressors. NACE MR0175/ISO 15156-3, Table A.2 applies to austenitic stainless steels used for any equipment or components.
    b) The limits on austenitic stainless steels in NACE MR0175/ISO 15156-3, Table A.6 (when compared to those of NACE MR0175/ISO 15156-3, Table A.2) are based upon industry experience with these alloys in compressors.
    c) The latest editions of API Standard 618 for Reciprocating compressors and API Standard 617 for Axial and Centrifugal compressors define the scope of equipment associated with the compressor environment including accessories, instrumentation, and piping systems.
    d) It is the user’s responsibility to determine if the pipe mentioned in your inquiry is directly associated with the compressor and experiences the same service environment as inferred for compressors in NACE MR0175/ISO 15156-3,Table A.6.
    e) The Maintenance Panel cannot review individually designed equipment and pressure stations to make this interpretation.
    2a) The manufacturer and user may consider documenting previous experience with pipelines in accordance with NACE MR0175/ISO 15156-1, Paragraphs 8.2 and 9.0.
    b) NACE MR0175/ISO 15156-1:2001 provides minimal requirements for these issues and the user is ultimately responsible for ensuring the alloy in final fabricated form has adequate resistance to the types of cracking listed in the Scope 1.0 of NACE MR0175/ISO 15156-1:2001.
    3. The ISO Maintenance Panel cannot comment on the suitability of using the 304L SS materials compared to alternative alloys.

    This question is in relation to NACE MR0175/ISO 15156-3 Table A.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2004-02

     

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  • 104. As per NACE MR0175, austenitic stainless steel weldments need to be solution annealed and quenched?
     

    Question: I am requesting a clarification of intent for comments included in Tables A.2 and A.6 In both of these tables there is a statement "these materials shall also be in the solution-annealed and quenched condition." It is my interpretation that this was a requirement for the base material and was not intended for a fabricated part, e.g., a welded compressor housing. We have to complete some fabrications and believe the required heat treatment will cause cracking and distortion of the part--however, a part must meet the requirements of MR0175/ISO 15156.

    Answer:

    You are correct. NACE MR0175/ISO 15156-3, Tables A.2 and A.6 apply to base materials only. The requirements for welding are given in NACE MR0175/ISO 15156-3, A.2.3, "Welding of austentitic stainless steels of this materials group."

    This question is in relation to NACE MR0175/ISO 15156-3 Table A.2

    Reference: ISO 15156 Maintenance Panel Inquiry #2006-10

     

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  • 105. In NACE MR0175, how are bourdon tubes classified?
     

    Question:

    In the latest NACE MR0175 there are two component categories "Instrument tubing and associated compression fittings,..." and "Diaphragms, pressure measuring devices and pressure seals." To which category does the Bourdon tube belong?

    Answer:

    Bourdon tubes are not specifically addressed in NACE MR0175/ISO 15156.  The Maintenance Panel cannot meet your request to categorize Bourdon tubes between "Instrument tubing and associated compression fittings,..." and "Diaphragms, pressure measuring devices and pressure seals."
    In all cases the material selected must be acceptable to the equipment user for their service conditions.

    This question is in relation to NACE MR0175/ISO 15156-3  A.2.2, Table A.4

    Reference: ISO 15156 Maintenance Panel Inquiry #2007-01

    Talk to our corrosion consultants and oilfield metallurgists to select acceptable equipment for sour service conditions.

     

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  • 106. For CRAs in NACE MR0175, how does the 22HRC value convert to other hardness scales?
     

    Question:In Section of Part 3: Table A.2 (austenitic stainless steel) states: "These materials shall also -be in the solution-annealed and quenched, or annealed and thermally stabilized heat-treatment condition, -be free of cold work intended to enhance their mechanical properties, and -have a maximum hardness of 22 HRC." Whereas for welding in Section A.2.3 it is stated that: "The hardness of the HAZ after welding shall not exceed the maximum hardness allowed for the base metal, and the hardness of the weld metal shall not exceed the maximum hardness limit of the respective alloy used for the welding consumable." I addition Section 6.2.2.2.2 states that "Hardness testing for welding procedure qualification shall be carried out using Vickers HV 10 or HV 5 methods in accordance with ISO 6507-1 or the Rockwell 15N method in accordance with ISO 6508-1. The use of other methods shall require explicit user approval."

    Q1. Please clarify how the requirement for 22 HRC is interpreted in light of this, i.e., what Vickers (HV 10 or HV 5) or Rockwell (15N) value should be used as a maximum for weld HAZ and weld metal? On an associated point, for solid-solution nickel-based alloys (Section A.4) and duplex stainless steels (Section A.7) there are no hardness requirements for materials in the solution-annealed condition (with the exception of one HIP duplex stainless steel alloy). The relevant sections (A.4.3 and A.7.3) on welding state: "The hardness of the HAZ after welding shall not exceed the maximum hardness allowed for the base metal, and the hardness of the weld metal shall not exceed the maximum hardness limit of the respective alloy used for the welding consumable".

    Q2. Please confirm that the interpretation that NACE MR0175/ISO 15156 therefore places no hardness restrictions for welds in these materials is correct.

    Answer

    (1) NACE MR0175/ISO 15156 provides no guidance for hardness conversion from the Vickers to the Rockwell scales for the austenitic stainless steels, which is then left to an agreement between the manufacturer and the equipment user possibly based on conversion tables made using empirical data; see ISO 15156-3, 6.2.1, Paragraph 2.

    (2) There are no hardness limits for the HAZ of welds of corrosion-resistant alloys when there are no hardness limits in the tables or the text of the document for the base materials.
    For the weld metal, any hardness limit depends on any hardness limit set for the alloy used as consumable. For matching consumables for solid-solution nickel-based alloys (Section A.4) and duplex stainless steels (Section A.7) there are no hardness limits for weld metal.

    This question is in relation to NACE MR0175/ISO 15156-3 Annex A.2.3

    Reference: ISO 15156 Maintenance Panel Inquiry #2005-13

    At Oil & Gas Corrosion we can help you set the hardness requirements for CRAs in order to meet NACE MR0175 compliance.

     

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  • 107. According to NACE MR0175, can UNS S20910 be used for choke valve stems as well as valve stems?
     

    Question: Can UNS S20910 be used in the condition specified in table A.3 for choke valve stems as well as valve stems?

    Answer: Yes, table A.3 includes choke valve stems since chokes are considered to be a type of valve in the Oil & Gas Industry.

    This question is in relation to NACE MR0175/ISO 15156-3 A.3 Table A.3

    Reference: ISO 15156 Maintenance Panel Inquiry #2015-06

     

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  • 108. Does NACE MR0175 allows UNS S20910 to be used in the hot rolled or solution annealed and hot rolled condition?
     

    Question:

    UNS S20910 can be used for the applications in Table A.3 in the hot rolled or solution annealed and hot rolled conditions as long as the hardness does not exceed 35 HRC.

    Answer:

    This question is in relation to NACE MR0175/ISO 15156-3 Table A.3

    Reference: ISO 15156 Maintenance Panel Inquiry #2015-06

     

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  • 109. In NACE MR0175, is UNS S20910 acceptable in hot worked conditions?
     

    Question: In NACE MR0175, is UNS S20910 acceptable in hot worked conditions?

    Answer:

    The Table A.3 permits cold working to 35 HRC as long as the material has a solution annealing cycle that precedes it. The UNS S20910 is acceptable per the applications of Table A.3 in the hot worked condition that is subsequently solution annealed and cold worked to 35 HRC. The UNS S20910 is acceptable per the applications of Table A.3 in the hot worked condition as long as it is free of cold work intended to enhance mechanical properties and has a maximum hardness of 35 HRC. The condition of UNS S20910 in the hot worked condition followed only by cold working that enhances mechanical properties is not addressed in Table A.3; changing Table A.3 to permit this condition would require a successful ballot.

    This question is in relation to NACE MR0175/ISO 15156-3 Table A.3

    Reference: ISO 15156 Maintenance Panel Inquiry #2014-09R

     

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  • 110. For austenitic stainless steels (304, 316/316L etc), is there a limit of cold work in NACE MR0175?
     

    Question:

    In several paragraphs of both NACE MR0175 and ISO 15156 it is stated that materials (e.g., austenitic SS) are acceptable if they are free of cold work intended to enhance their mechanical properties or is stated "in the annealed or solution-annealed condition only" (e.g., Ni-based only). Question: Is there a limit to what is considered cold work, e.g., 5%, or is any cold work whatsoever included?

    answe:

    NACE MR0175/ISO 15156-3 does not prohibit all cold work of the austenitic stainless steels; it prohibits cold work intended to enhance mechanical properties. A limit for the percentage of cold work is not provided.

    This question is in relation to NACE MR0175/ISO 15156-3 A.3 and A.4

    Reference: ISO 15156 Maintenance Panel Inquiry #2003-28 Q1

     

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  • 111. If hydrotesting induces cold deformation, is this acceptable as per NACE MR0175?
     

    Question:

    In order to decrease the danger of low stress creep we slightly overstress superaustenitic SS and Ni-based alloy valve bodies during hydrotesting. This overstressing causes a "cold deformation" of 0.2-0.5%. We do not use the cold deformation in order to enhance the mechanical properties! Is this practice allowed under the rules of NACE MR0175/ISO 15156 ?

    Answer:

    Hydrotesting the austenitic stainless steels to the appropriate industry or design code is acceptable.

    This question is in relation to NACE MR0175/ISO 15156-3 A.3 and A.4

    Reference: ISO 15156 Maintenance Panel Inquiry #2003-28 Q2

     

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  • 112. Is alloy 600 (UNS N06600) included in NACE MR0175?
     

    Currently Alloy 600 (UNS N06600) is not listed in NACE MR0175.

    Question: Your name was given to me as someone that might be able to help sort out an issue that was raised by one of my co-workers. At one point many years ago, alloy 600 (UNS N06600) was included in MR0175 as a specific alloy that could be used in NACE applications. For some reason along the way with the revisions between 2002/2003 and the changeover to ISO 15156, it has been left out or removed on purpose. However, I was not able to find out specifically what happened to alloy 600. A friend did a search of ISO 15156 and found a query on the same topic (2011-03 on UNS N06600) with the same question as mine. The proposed response was as listed below: “N06600 is not listed in 15156 as an acceptable alloy. There is currently a ballot proposal to introduce UNS N06600 back into NACE MR0175/ISO 15156 Standard. According to ISO 15156 rules this ballot will have to pass votes from the Maintenance Panel and the Oversight Committee to be accepted”. No records of the proposed ballot were found. Not sure what happened to this. I was told that my inquiry should be sent to you to be able to get the formal inquiry recorded and entered into the NACE system so that the Maintenance Panel would be able to investigate. I do appreciate your help. If you have any questions, please let me know.

    Answer:

    Item 4 in Minutes of meeting from San Antonio MP meeting: Nickel Alloy 600 ballot. Alloy 600 was in the previous version of MR0175 and left off in translation into 15156. The proposal was to relist without limits in annealed conditions with 35 HRC maximum. The ballot submitter was asked to resubmit with data or use history; we have not had a reply as of this meeting.

    Reference: ISO 15156 Maintenance Panel Inquiry #2014-06

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  • 113. NACE MR0175 Table A.6, does it cover pressure gauges, transmitters, diaphragms etc?
     

    Question:

    Our inquiry is regarding Table A.6, in which the material and environmental limits for instrumentation and control devices are described. The note b in Table A.6 only provides an indication of possible components that fall in this category (diaphragms, pressure measuring device and pressure seals). However, we do not fully understand if the following instruments also fall in this category. - pressure gauges (with bourdon tube or diaphragms) - diaphragm seals/chemical seals - electronic pressure transmitters - electric and mechanical temperature measuring devices - Accessories o Restrictor Overpressure protector o Thermowell (solid machined, fabricated) o Syphon o Cooling tower Do you agree that the above mentioned instruments fall in the category as noted in Table A.6. ?

    Answer:

    Table A.6 includes instrumentation and control devices that have been used so far without known failures in sour service. It is up to the Manufacturer to assess if the use of austenitic stainless steel instrumentation and control devices used for compressors are included in Table A.6. The Maintenance Panel cannot give advice on specific design issues. The applicability of Table A.6 to specific components must be agreed between the user and manufacturer. You are encouraged to submit a ballot to revise/clarify Table A.6. This ballot should include field history as prescribed in 15156-1 clause 8.2.

    This question is in relation to NACE MR0175/ISO 15156-3 Table A.6

    Reference: ISO 15156 Maintenance Panel Inquiry #2011-02

     

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  • 114. What are the NACE MR0175 limits for UNS J93254 (A351 CK3MCuN)?
     

    Question:

    We have requirement of 6Mo valves for one of our ongoing projects wherein we need to use A 351 CK3MCuN (J 93254) body material. With reference to Table A -8 of NACE MR0175/ISO-15156 - 2003 Environmental and materials limits for highly alloyed austenitic steels used for any equipment or components ) we have following clarification: Table A - 8 lists the above material J 93254 (ASTM A 351 CK3MCuN) can be used for any combinations of temperature, pH2S, chloride concentration and in situ pH occurring in production environments are acceptable. We understand that forging grade equivalent of above J 93254 which is UNS 31254 will also be qualified under these conditions. Please confirm /clarify the whether forging grade equivalent of J 93254 which is UNS 31254 will also be qualified?

    Answer:

    Table A.8 is the subject of an amendment proposal that has been accepted by the ISO 15156 Maintenance Panel, by NACE TG 299 (ISO 15156 Oversight Committee) and by ISO TC67 WG7 and will now go forward for publication.
    The revision involves limits being placed upon the application of UNS J93254. Publication of this document can be expected within the coming year.

    This question is in relation to NACE MR0175/ISO 15156-3 A.3.2, Table A.8

    Reference: ISO 15156 Maintenance Panel Inquiry #2006-12

    UPDATE: NACE MR0175 / ISO 15156 latest revision includes an update on the UNS J93254 limits.

     

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  • 115. NACE MR0175, UNS S31600, S30940 and types 3a and 3b, what is the difference?
     

    Question:

    We are doing a pipe skid system that requires ASME B31.3 and NACE MR0175 as project requirements. According to A.3.2 of NACE MR0175, Table A.8 lists some material UNS numbers. We are wondering what NACE means by “type 3a” and “3b” (max temp 140 deg F). The pipe we were contemplating using was ASTM A312 Gr TP 316. According to another chart we saw that the equivalent URN (UNS) number for A312 is S30940. What therefore is the maximum temperature rating on S30940 (ASTM A316 Gr TP316). Our application is on frame oil where the design values are -18 to 160 deg C, 300 lb.

    Answer:

    The definition of materials type 3a and 3b is given at the bottom of Table A.8. It is based on alloy chemical composition. The temperatures given in the tables are the maximum known acceptable values with the given H2S partial pressure, pH, and chlorides limits. The alloys UNS S31600 and S30940 you are referring to are austenitic stainless steels and are covered by Table A.2 and Clause A.2. The MP does not answer questions concerning specific applications.

    This question is in relation to NACE MR0175/ISO 15156-3  A.3.2, Table A.8

    Reference: ISO 15156 Maintenance Panel Inquiry #2010-12

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  • 116. In NACE MR0175 Table A.2, are the chemistry requirements additive?
     

    Question:

    We have a question regarding the meaning of a sentence in Paragraph 4.4 in MR0175-2003. This same sentence is repeated in Paragraph 10.2.1. 62 The paragraph states: Highly alloyed austenitic stainless steels in this category are those with Ni% + 2 Mo% >30 and 2% Mo minimum. A1. Does the statement mean that there are essentially two groups in this category? Such that . . . One qualifying group consists of materials that contain N% + 2 Mo% >30 Another qualifying group consists of any austenitic stainless steel with 2% Mo minimum (such as 316, 317). A2. Or does the statement mean that there must be a minimum of 2% Mo in the Ni% + 2 Mo% >30 requirement? Since the environmental restrictions in Paragraph 4.4 are the same as in 4.2 (where most austenitics are acceptable), I assume #A1 is the correct interpretation since this would allow for inclusion of 316 and 317.

    answer:

    Your answer A2 is correct. The chemistry requirements are additive.

    This question is in relation to NACE MR0175/ISO 15156-3 A.3.2, Table A.8 and Table A.9

    Reference: ISO 15156 Maintenance Panel Inquiry #2003-15

     

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  • 117. What are the NACE MR0175 environmental limits for UNS S31254?
     

    Question: NACE Standard MR0175-2003 has two different highly alloyed austenitic SS families, one (Paragraph 4.4) with Ni% + 2 Mo% >30 (and Mo>=2%) and one (Paragraph 4.5) with PREN >40. Both have two different ranges for temperature, partial H2S partial pressure, and maximum chloride content. Which environmental limits have to be used for materials applicable for both categories like UNS S31254?

     

    Answer:

    If UNS S31254 has a PREN >40, then the less restrictive environmental limits in Paragraph 4.5 apply.

    This question is in relation to NACE MR0175/ISO 15156-3  A.3.2, Table A.8 and Table A.9

    Reference: ISO 15156 Maintenance Panel Inquiry #2003-19 Q1a

     

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  • 118. in NACE MR0175, what Types in Table A.12 cover UNS N08825?
     

    Question: in NACE MR0175, what Types in Table A.12 cover UNS N08825?

    Answer:

    UNS N08825 meets type 4a and 4c in Table A.12.

    This question is in relation to NACE MR0175/ISO 15156-3  A.4, Table A.12

    Reference: ISO 15156 Maintenance Panel Inquiry #2015-08

     

     

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  • 119. In NACE MR0175, is UNS N08825 resistant to sulfur without limitations on pH, temperature, pH2S and chloride?
     

    Question: Is UNS N08825 resistant to sulfur without limitations on pH, temperature, pH2S and chloride? In the remarks column in Table A.13 the following is stated: “…some combinations of the values of these parameters might not be acceptable”. How should this be interpreted?

    Answer:

    Table A.14 currently states that Type 4c alloys including UNS N08825 are resistant to sulfur under any combination of conditions up to and including 132°C (270°F). Note that recent discussions in the Maintenance Panel have highlighted that the term “sulfur resistant” is not adequate (conservative) in itself and there is activity currently underway defining levels of resistance that are determined through three different test techniques and resultant 3 groups (#1 where successful tests were conducted using 1 g/l dissolved sulfur, #2 where there is direct exposure to solid sulfur – applicable below 110°C and #3 direct exposure to liquid sulfur – applicable for temperatures above 110°C). The user is cautioned that even though there are no environmental limits currently defined below 132°C for UNS N08825, there could be some combinations of parameters including elemental sulfur form (i.e. physically dissolved, solid or liquid) that may not be acceptable.

    This question is in relation to NACE MR0175/ISO 15156-3 A.4, Table A.12

    Reference: ISO 15156 Maintenance Panel Inquiry #2015-08

     

     

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  • 120. Is UNS N08020 listed in NACE MR0175 / ISO 15156?
     

    Question: I am looking for a definitive interpretation of NACE MR0175 concerning nickel-based alloys. My company produces alloy 20 (UNS N08020). The standard ASTM/AMS/UNS composition is listed in Table D3 on pg. 65 showing a Mo range of 2.0-3.0. Section A.4 of MR0175 contains Table A.12--Materials types of solid solution nickel-based alloys. This table does not list any specific alloys, but it does list the minimum Mo (which I assume is for compliance with the standard) at 2.5%. Does that mean that in order to certify our 20Cb3 to MR0175 the heat must have at least 2.5% Mo, even though the acceptable Mo range is 2.0-3.0? If so, what is the impetus behind requiring a higher Mo range than is standard for the alloy?

    Answer:

    You are correct, a minimum of 2.5% Mo is required for N08020 to be compliant with Table A.12, material types 4a and 4c. Heats of N08020 not meeting the 2.5% Mo minimum may be acceptable as "Highly alloyed austenitic stainless steels" under the limits provided in Tables A.8, A.9, and/or A.11.
    The 2.5% Mo restriction for N08020 is similar to the PREN restrictions for Duplex Stainless steels. The full chemistry ranges of the UNS numbers listed in the Annex D tables are for reference only.

    This question is in relation to NACE MR0175/ISO 15156-3 A.4, Table A.12

    Reference: ISO 15156 Maintenance Panel Inquiry #2011-07

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  • 121. Is NiMo16Cr16Ti (TUV Specification 429 09.2002 Material No 2.4610) qualified to NACE MR0175?
     

    Question:

    We produce a highly corrosion resistant NiMo 16 Cr 16 Ti alloy to the German TUV Specification 429 09.2002 Material No 2.4610. Could you please confirm that this material complies with the requirements for materials Types 4b and 4e of NACE MR0175/ISO 15156:2009 Part 3 Annex A Table A.12?

    Answer:

    If, in addition to the TUV specification, this material also satisfies the requirements of UNS N06455 with a minimum chromium content of 14.5%, it does comply with the requirements for Type 4b and 4e provided the metallurgical conditions defined in Table A.12 are also fulfilled.

    This question is in relation to NACE MR0175/ISO 15156-3 A.4, Table A.12

    Reference: ISO 15156 Maintenance Panel Inquiry #2014-01

     

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  • 122. Alloy UNS N06625 (Alloy 625) and compliance with NACE MR0175/ISO 15156-3, quenched off the hammer or separate annealing?
     
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  • 123. In NACE MR0175, what is the API 5CT L-80 Type 13Cr hardness limit?
     

    Question:

    Is the maximum hardness limit for ISO 11960 L-80 Type 13 Cr tubing used as a downhole tubular component, packer, and other subsurface equipment in accordance with NACE MR0175/ISO 15156 the maximum hardness as specified in the latest edition of ISO 11960? Note: ISO 11960 is also designated as API 5CT. Note: ISO 11960 currently specifies 23 HRC as the maximum hardness for L-80 Type 13 Cr tubing. Discussion: NACE MR0175/ISO 15156-3, Table A.19 lists ISO 11960 L-80 Type 13 Cr and two other materials as begin acceptable for "downhole tubular components, packers, and other subsurface equipment." There are notes in this table that specify the maximum hardness limits of the other two materials, individually. However, there is no note to specify the maximum hardness limit of ISO 11960 L-80 Type 13 Cr tubing. This seems to indicate that ISO 11960 becomes the controlling document for L-80 Type 13 Cr, and therefore the maximum hardness for ISO 11960 L-80 13 Cr tubing is currently 23 HRC as specified in Table C.6 and Table E.6 of ISO 11960.

    Answer:

    Your interpretation is correct.
    As a general rule during the preparation of ISO 15156, the unnecessary repetition of information provided in cited sources was avoided.

    This question is in relation to NACE MR0175/ISO 15156-3 A.6.2, Table A.19

    Reference: ISO 15156 Maintenance Panel Inquiry 2006-03

     

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  • 124. In NACE MR0175, Why are tubing and subsurface equipment treated as two separate categories?
     

    Question:

    I need to clarify a confusion about NACE MR0175/ISO 15156-3. Why are tubing and subsurface equipment in Tables A.19 and A.20, respectively, treated as two separate categories? Tubing itself is subsurface equipment so why is it treated separately? Moreover, K90941 as mentioned in Table A.20 is recommended for subsurface equipment under any H2S partial pressure but not for tubing, exposed to the same condition; why? L-80 type 13 Cr is more cracking-resistant material than K90941; still it is not recommended for subsurface equipment apart from tubing; why? We are in a process of developing a sour gas field and purchased a copy of this standard to be a guideline for material selection. We need answers to these questions so we can select the most appropriate material for downhole casing/tubing.

    Answer:

    NACE MR0175/ISO 15156-3 reflects the experience of the oil industry and its experts in the use of materials in sour service over many years.
    The separation of materials into Tables A.19, A.20, and A.21 allowed convenient grouping of the data available.
    In some cases the differences you identify reflect the availability of different product forms manufactured from the different materials.
    As indicated in the title of Table A.19, ISO 11960 L80 type 13Cr is acceptable for other subsurface equipment (other than tubing) providing the material fully meets the applicable material requirements of ISO 11960 L80 type 13Cr. Additionally as indicated in the title and notes of Table A.21, 420 (modified) having the chemical composition of ISO 11960 L80 type 13Cr is acceptable for packers and subsurface equipment.
    In all cases the data presented reflect successful laboratory testing of an alloy or successful field experience with the alloy used in the product form listed.
    For martensitic alloys not listed in Tables A.19, A.20, and A.21 qualification of the alloy for use in accordance with ISO 15156-3 can be carried out in accordance Annex B.

    This question is in relation to NACE MR0175/ISO 15156-3 A.6.2, Table A.19, A.20 and A.21

    Reference: ISO 15156 Maintenance Panel Inquiry #2005-22

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  • 125. How to evaluate the microstructure of duplex stainless steels welding for NACE MR0175?
     

    NACE MR0175, DNV-RP-F112, Norsok M630 and BS4515-2 are just some of the design codes and standards that require exhaustive examination of the microstructure of duplex and superduplex stainless steels. At Oil & Gas Corrosion we can help you navigate through these requirements to make sure your equipment and materials are fit for purpose.

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    Question:

    ISO 15156-3, A.7.3--Regarding metallographic examination of the microstructure: a) Do closely spaced spheroidal precipitates such as grain boundary carbides constitute continuous precipitates? b) At what spacing would closely spaced spheroidal precipitates be considered continuous? c) Are the quantification of precipitates (intermetallic phases, nitrides, carbides) to be evaluated as a volume fraction relative to the bulk sample? d) In cases where only grain boundary precipitates are observed, is the quantification to be made as a volume fraction relative to the bulk sample or as a lineal fraction relative to grain boundary length? e) In the absence of intermetallic phases and nitrides, does 1 vol.% represent the maximum allowable carbide precipitate content? f) What is a suitable recommended practice or standard by which to perform this quantification?

    Answer:

    a), b), e)  For NACE MR0175/ISO 15156-3, A.7.3 it is the responsibility of the equipment user and the manufacturer to set the quantitative standard they wish to follow when this goes beyond the guidance given.

    c), d), f)  It is the responsibility of the equipment user and the manufacturer to agree on the method and acceptance criteria for the measurement of precipitates.

    This is in relation to NACE MR0175/ISO 15156-3 A.7.3

    Reference: ISO 15156 Maintenance Panel Inquiry #2005-28

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  • 126. In NACE MR0175, Are 17-4PH hangers considered "subsurface equipment"?
     

    Question:

    Reference: NACE MR0175/ISO 15156-3 Table A.27--Environmental and materials limits for martensitic precipitation-hardened stainless steels used for wellhead and christmas tree components (excluding bodies and bonnets), valves and chokes (excluding bodies and bonnets) and packers and other subsurface equipment API 6A makes a distinction between hangers and body components. NACE MR0175/ISO 15156 doesn't define either. This has led to some confusion regarding whether or not UNS S17400 material may be used as hangers in a sour environment.

    Q1. Does the exclusion of wellhead "bodies and bonnets" in Table A.27 also mean that hangers are excluded?

    Q2. Are hangers considered "subsurface equipment" in the context of Table A.27?

    Q3. Does Table A.27 prohibit the use of UNS S17400 material for hangers in sour service?

    A1. No, it does not.
    A2. In the context of Table A.27, hangers are more commonly considered to be covered by the term "wellhead and christmas tree components."
    A3. No, it does not provided the environmental limits and metallurgical requirements of Table A.27 are followed.
    See also response to MP Inquiry #2006-07 posted under ISO 15156-3, Table A.3.

    This is in relation to NACE MR0175/ISO 15156-3 A.8.2, Table A.27

    Reference: ISO 15156 Maintenance Panel Inquiry #2005-12

    Update April 2016: NACE MR0175 2015 - Technical Circular 1 has implications for 17-4PH. Contact us for more details.

    Are you using 17-4PH (UNS s17400) as a material for sour environments? We can provide support in 17-4PH metallurgy to safeguard the integrity of your asset.

     

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  • 127. If a weld is qualified to NACE MR0175, is NACE TM0177 required?
     

    Question:

    About welds, in accordance with NACE MR0175/ISO 15156, Part 2, Item 7.3.3.4, "hardness acceptance criteria for welds," "weld hardness acceptance criteria for steels selected using option 1 (see 7.1) shall be as specified in A.2.1.4. Alternative weld hardness acceptance criteria may be established from successful SSC testing of welded samples. SSC testing shall be in accordance with Annex B." So, in our understanding, if our welding procedure qualifications (WPSs) are qualified in accordance with NACE MR0175/ISO 15156, Part 2, Item A.2.1.4, it is not necessary to test them according to NACE TM0177. We would like you to confirm whether our interpretation below is correct and if not give us the correct interpretation.

    Answer:

    Your interpretation is correct.

    Question:

    NACE MR0175/ISO 15156 and NACE TM0177--WELDS
    On the other hand, if we make the test in accordance with NACE TM0177 in our WPSs that are previously qualified to conform to NACE MR0175/ISO 15156, what kind of results will we have? Will we have necessary or redundant results?

    Answer:

    A manufacturer may choose to qualify a welding procedure specification in accordance with ANNEX B. Testing welds acceptable in accordance with A.2.1.4 is an optional activity chosen by the manufacturer to confirm resistance to cracking. This is not necessarily a redundant result depending on the anticipated service conditions and the selected test environment, the results could be used
    -to confirm that the hardness control specified in A.2.1.4 is adequate to prevent sulfide stress cracking
    -or to define alternative weld hardness control requirements that will not lead to sulfide stress cracking when the requirements of A.2.1.4 are not met.

    Reference: ISO 15156 Maintenance Panel Inquiry #2005-08 Q1, Q2 and Q3

    This question is in relation to NACE MR0175/ISO 15156-1 Clause 7

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  • 128. NACE MR0175 limits for UNS N06975 and UNS N10276
     

    Question:

    (a) NACE MR0175/ISO 15156-3, Sub-clause A.4.2, Table A.14 permits sulfur at 300°F in any H2S partial pressure, but not at 425°F. Where, if anywhere, between 425°F and 300°F are alloys in this category sulfur-resistant? If an oil-company client has a well with bottom-hole temperature of 350°F with produced brine that contains sulfur, will an alloy like 2550 (UNS N06975) be sufficiently resistant,

    (b) must C-276 (UNS N10276) be deployed?

    Answer

    (a) In some cases the comparisons you make are not strictly valid because the data sets for the materials considered vary in the H2S limits, in the temperature limits, and in the metallurgical limits that are imposed. It is thought that the limits given are conservative and further testing could demonstrate that the true limits are less restrictive than those shown.

    (b) UNS N10276 would be acceptable.

    This question is in relation to NACE MR0175/ISO 15156-3 A.4.2, Table A.14 and A.33

    Reference: ISO 15156 Maintenance Panel Inquiry #2003-13 Q4

     

     

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  • 129. In NACE MR0175 Table A.22, are martensitic stainless steels "limitless"? Do they need qualifying?
     

    Question:

    In NACE MR0175/ISO 15156 -3, Table A.22 lists the "Environmental and materials limits for martensitic stainless steels used as compressor components." The maximum partial pressure requirement for H2S directs you to see Remarks, and the Remarks state "Any combination of temperature, partial pressure of H2S, chloride concentration and in situ pH occurring in production environments are acceptable." Does this remark indicate that conformance to the NACE MR0175/ISO 15156 is required for any amount of H2S? I am looking for clarification as to what "acceptable conditions" is referring to. As a centrifugal compressor manufacturer, we often build compressors for process gases which are a hydrocarbon mix containing a few parts per million or trace amounts of H2S.

    Answer

    Conformance to the Standard is required for any trace amount of H2S. In the case of Table A.22 the listed martensitic stainless steels can be used in any production environment provided they are in conformance with the metallurgical requirements indicated in the lower part of the Table. Note that item c) in Table A.22 requires a resistance in the anticipated service environment of at least 95% of the actual yield strength of the impeller material using Annex B for laboratory testing. Qualification requirements to ISO 15156 are listed in §8 of NACE MR0175/ISO 15156-1.

    This question is in relation to NACE MR0175/ISO 15156-3 A.6.2, Table 22

    Reference: ISO 15156 Maintenance Panel Inquiry #2010-06

    If you need assistance selecting and qualifying material to Table A.22 contact us, we got the Technical Authority to help you.

     

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  • 130. NACE MR0175 and HIP materials used in valve components?
     

    Question:

    PM HIP materials are used in valve components. The reason we are doing this is that casting quality of high alloy material has been poor and lead times long. The required casting repair process is very expensive as well. Our questions: 1. Do these PM HIP materials fulfill the standard requirements of sour service if they have the same chemical and mechanical properties and heat treatment as their wrought or forged counterparts? 2. Do the same environmental limits apply for PM HIP materials as specified for the corresponding wrought alloys in the referred tables? [Tables referred to are A.24, A.8, A.13 in Part 3.]

    Answer:

    HIP materials have been separately listed so far as in Tables A.24 and A.33. Their resistance to sour service must be demonstrated by material qualification testing in accordance with ISO 15156-3 Annex B.

    This question is in relation to NACE MR0175/ISO 15156-3 Tables A.23 and A.24

    Reference: ISO 15156 Maintenance Panel Inquiry #2010-08

     

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  • 131. What does "continuous precipitates" mean in NACE MR0175?
     

    Question:

    See A.2.3, MP inquiry #2005-13. The question is in regard to Appendix A.7 of NACE MR0175/ISO 15156-3. In A.7.3 third paragraph, it requires that "the microstructure ... shall have grain boundaries with no continuous precipitates". Is there any guidance as to what continuous means? For example, does it mean continuous throughout the microstructure? Our laboratory has reported suspected continuous precipitates "at some locations".

    Answer:

    There is no definition of "continuous precipitates" in the standard. An acceptance criterion or other quantitative limit shall be agreed between the manufacturer/supplier and the equipment user.
    As noted in the WARNING above ISO 15156-3, Scope, it is the equipment user's responsibility to select the CRAs and other alloys suitable for the intended service. This responsibility includes the selection of specific quality requirements when none are given by the standard.

    This question is in relation to NACE MR0175/ISO 15156-3 A.7.3

    Reference: ISO 15156 Maintenance Panel Inquiry #2005-18

    Our oilfield metallurgy team can help you define the microstructural requirements to maintain integrity in duplex and superduplex built equipment. We can help you assure integrity and meet regulatory requirements such as NACE MR0175, DNV OS F101 and BS 4515-2.

     

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  • 132. Is UNS S66286 acceptable for tubing hanger according to NACE MR0175?
     

    Question:

    What grade of stainless steel meeting NACE requirements can be used for a tubing hanger when the pH is <3.5? My interpretation based on understanding of NACE MR0175/ISO 15156-3 Section A.8 Table A.26 is that only UNS S66286 is acceptable. Could you please confirm my statement or correct it?

    Answer:

    UNS S66286 is the only precipitation-hardenable stainless steel that is acceptable for tubing hangers in environments with pH <3.5. The martensitic stainless steels are also not acceptable for environments with pH <3.5.

    This question is in relation to NACE MR0175/ISO 15156-3 A.8, Table A.26

    Reference: ISO 15156 Maintenance Panel Inquiry #2004-13

     

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  • 133. What are the NACE MR0175 limits for UNS S66286
     

    Question:

    Table A.26 limits the precipitation-hardened austenitic steel UNS S66286 to 150°F and 15 psi H2S when chlorides are present. a) Can this material be used at higher temperature if no chlorides are present?

    Answer

    No, it may not. The table states that the temperature restriction is for "Any combinations of chlorides . . . " NACE MR0175/ISO 15156-3 does not define the expected performance of UNS S66286 in environments containing no chlorides.

    This question is in relation to NACE MR0175/ISO 15156-3 A.8, Table A.26

    Reference: ISO 15156 Maintenance Panel Inquiry #2005-02 Qa

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  • 134. What are the NACE MR0175 requirements for Gr. 660 subsea bolting external to the production wellbore?
     

    Question:

    Does NACE MR0175/ISO 15156-3 Table A.26 apply to Gr. 660 material used in subsea bolting applications external to the production wellbore environment when indirectly heated above 150°F?

    Answer:

    Table A.26 does not apply to Grade 660 material used in subsea bolting applications external to the production wellbore environment.

    This question is in relation to NACE MR0175/ISO 15156-3 A.8, Table A.26

    Reference: ISO 15156 Maintenance Panel Inquiry #2005-09Q2

     

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  • 135. What is the NACE MR0175 hardness limit for 17-4PH?
     

    Question: We have a requirement to supply NACE-compliant control valves for the oil and gas industry. One of our internal components is a part made from UNS S17400 (17-4 PH), details of which are described in Table A27 of Part 3 of the standard. NACE MR0175/ISO 15156-3 states this material should have a maximum hardness of 33 HRC, after one of the following heat treatment processes: HEAT TREATMENT (DOUBLE AGE-HARDENING PROCESS) 1) - SOLUTION-ANNEAL AT 1040±14°C AND AIR COOL OR LIQUID-QUENCH TO BELOW 32°C; - FIRST PRECIPITATION-HARDENING CYCLE AT 620±14°C FOR 4 HRS MINIMUM AT TEMPERATURE, THEN AIR-COOL OR LIQUID-QUENCH TO BELOW 32°C; - SECOND PRECIPITATION-HARDENING CYCLE AT 620±14°C FOR 4 HRS MINIMUM AT TEMPERATURE, THEN AIR-COOL OR LIQUID-QUENCH TO BELOW 32°C 2)- SOLUTION-ANNEAL AT 1040±14°C AND AIR COOL OR LIQUID-QUENCH TO BELOW 32°C; - FIRST PRECIPITATION-HARDENING CYCLE AT 760±14°C FOR 2 HRS MINIMUM AT TEMPERATURE, THEN AIR-COOL OR LIQUID-QUENCH TO BELOW 32°C; - SECOND PRECIPITATION-HARDENING CYCLE AT 620±14°C FOR 4 HRS MINIMUM AT TEMPERATURE, THEN AIR-COOL OR LIQUID-QUENCH TO BELOW 32°C. Ultimately we are trying to establish if these components are still compliant and if not, what we can do to rework the parts. Other materials such as 316 state an annealing process, but there is not one for UNS S17400. In addition, the components are “delicate” in design so post-machining heat treatment is probably not desirable due to component distortion. What does the hardness of 33 HRC refer to, wrought bar or finished component? What, if anything, can we do to rework these parts if the hardness value refers to the finished (machined) condition?

    Answer

    The 33 HRC max. hardness is applicable to the finished component. The MP does not provide consulting service for material processing issues.

    This is in relation to NACE MR0175/ISO 15156-3 A.8.2, Table A.27

    Reference: ISO 15156 Maintenance Panel Inquiry #2011-16

    Update April 2016: NACE MR0175 2015 - Technical Circular 1 has implications for 17-4PH. Contact us for more details.

    Are you using 17-4PH (UNS s17400) as a material for sour environments? We can provide support in 17-4PH metallurgy to safeguard the integrity of your asset. 

     

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  • 136. What are the NACE MR0175 limits for UNS S17400 safety relief valves and subsurface equipment?
     

    Question: Use of SST 17-4 PH UNS S17400 material for NACE is listed in NACE MR0175/ISO 15156-3, Tables A.27, A.28, and A.30. Only Table A.27 contains limitations for partial pressure H2S and PH. Questions: (1) For surface safety relief valves with internal components made of SST 17-4 PH heat treated and hardness tested to limits specified, do the limits of Table A.27 or A.28 apply? Internal components are considered non-pressure retaining by definition 3.4 in Part 2. However, failure of an internal component can cause release of service fluid to the valve outlet. It is assumed for NACE applications that safety relief valves for NACE service would not be vented to atmosphere. (2) Does Part 3 Table A.28 only apply to subsurface equipment or does it apply to all valves?

    Answer:

    The equipment user is responsible for defining the intended service environment and selecting materials in accordance with this standard.

    This is in relation to NACE MR0175/ISO 15156-3 A.8.2, Table A.27, A.28 and A.30

    Reference: ISO 15156 Maintenance Panel Inquiry #2011-17

    Update April 2016: NACE MR0175 2015 - Technical Circular 1 has implications for 17-4PH. Contact us for more details.

    Are you using 17-4PH (UNS s17400) as a material for sour environments? We can provide support in 17-4PH metallurgy to safeguard the integrity of your asset.

     

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  • 137. What does "17-4PH service tool applications mean" in NACE MR0175 Table A.28,?
     

    Question: Can you provide clarification on NACE MR0175/ISO 15156-3, Table A.28: “UNS S17400 …. has been used in service tool applications at the surface when stressed at less than 60% of its minimum specified yield strength under working conditions.” This Table also lists “Internal Components for Valves, Pressure Regulators, and Level Controllers”. What exactly do service tool applications encompass?

    Answer:

    This paragraph is intended to apply to components that are temporarily installed at the surface as part of routine well servicing. For example, components of wireline valves used during a wireline job are considered as service tools.

    This question is in relation to NACE MR0175/ISO 15156-3 A.8.2, Table A.28

    Reference: ISO 15156 Maintenance Panel Inquiry #2003-32

    Update April 2016: NACE MR0175 2015 - Technical Circular 1 has implications for 17-4PH. Contact us for more details.

    Are you using 17-4PH (UNS s17400) as a material for sour environments? We can provide support in 17-4PH metallurgy to safeguard the integrity of your asset.

     

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  • 138. in NACE MR0175, is UNS S17400 acceptable for use in compressors?
     

    Question: NACE MR0175/ISO15156-3,Table A.30: Are wrought UNS S17400 and S15500 martensitic precipitation-hardenable stainless steels that meet the hardness and heat-treat requirements of this Table acceptable for use in compressors in sour environments with no environmental limits with respect to chloride content, partial pressure of H2S, temperature, and free elemental sulfur? QUESTION: If the answer to the former question is no, what are the specific environmental limits?

    Answer:

    Yes, they are acceptable with no environmental limits in accordance with NACE MR0175/ISO 15156 Table A.30. No data have been submitted to verify resistance to cracking in the presence of elemental sulfur.

    This question is in relation to NACE MR0175/ISO 15156-3 A.8.2, Table A.30

    Reference : ISO 15156 Maintenance Panel Inquiry #2003-34

    Update April 2016: NACE MR0175 2015 - Technical Circular 1 has implications for 17-4PH. Contact us for more details.

    Are you using 17-4PH (UNS s17400) as a material for sour environments? We can provide support in 17-4PH metallurgy to safeguard the integrity of your asset.

     

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  • 139. What are the NACE MR0175 limits for alloy 718 (UNS N07718)?
     

    Question

    Our question relates to ISO 15156-3, Table A.32: How should the table be interpreted in terms of the maximum allowable temperature for applications with less than 30 psi partial pressure of H2S? For example, in its current layout the table prohibits the use of UNS N07718 at temperatures higher than 450°F at any H2S pressure below 30 psi.

    Answer:

    ISO 15156-3, Table A.32 does not qualify UNS N07718 for use at higher temperatures than 450°F.
    The limits on temperature, H2S, Cl-, pH, and sulfur defined in some of the tables of ISO 15156-3, Annex A apply collectively and reflect the knowledge available, usually from laboratory tests, at the time the standard was published. There were no data available related to the use of UNS N07718 at any temperature higher than 450°F.

    ISO 15156 allows the qualification and use of materials, to an equipment user's requirements, outside the limits stated in the tables. (See ISO 15156-3, Figure B.1, Column 2.)

    A qualification to define an alternative temperature limit for UNS N07718 for a partial pressure of H2S less than 30 psi must be carried out in accordance with ISO 15156-3, Annex B.

    This question is in relation to NACE MR0175/ISO 15156-3 A.9.2, Table A.32

    Reference: ISO 15156 Maintenance Panel Inquiry #2005-20

    Our corrosion consultants and oilfield metallurgists can help you evaluate the production environment and validate your alloy 718 selection.

    UPDATE 2018-06-04: A recent Technical Circular brings relevant updates on NACE MR0175 including Inconel 718: https://oilandgascorrosion.com/nace-mr0175-iso-15156-technical-circulars-for-part-2-and-3-published-2018-06-01/

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  • 140. NACE MR0175 requirements for 718 springs
     

    Question:

    We are having some discussions with a user who tells us that Table A.32 ‘Environmental and materials limits for precipitation-hardened nickel-based alloys used for any equipment or component’ can be referred to for spring materials, and therefore Inconel N07718 can be used for spring as long as it is solution-annealed and aged to a maximum hardness of 40 HRC. However the Table A.36 ‘Environmental and materials limits for precipitation-hardened nickel-based alloys used as springs’ does not list N07718. How should I interpret these tables for nickel-based alloys springs? Can I follow table A.32?

    Answer:

    Materials listed in 15156-3 Table A.32 are acceptable for “any equipment or component” including springs. Other materials from other “any equipment or components” tables may also be acceptable for springs if used within the metallurgical and environment limits specified in the applicable tables.

    This question is in relation to NACE MR0175/ISO 15156-3 A.9.2, Table A.32

    Reference: ISO 15156 Maintenance Panel Inquiry #2013-03

    UPDATE 2018-06-04: A recent Technical Circular brings relevant updates on NACE MR0175 including Inconel 718: https://oilandgascorrosion.com/nace-mr0175-iso-15156-technical-circulars-for-part-2-and-3-published-2018-06-01/

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  • 141. Does NACE MR0175 apply to springs that are plastically deformed (not more than 1 or 2% strain)?
     

    Question:

    Does NACE MR0175 / ISO 15156 apply when areas of a spring are plastically deformed (not more than 1 or 2% strain)?

    Answer:

    NACE MR0175/ISO 15156 does not apply to design made with plastic deformation criteria, as written in Paragraph 5 of Part 1. Qualification through testing or field experience may be used to qualify this type of design but this will be outside the limits of the standard.

    This question is in relation to NACE MR0175/ISO 15156-3 Table A.39

    Reference: ISO 15156 Maintenance Panel Inquiry #2009-05

     

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  • 142. NACE MR0175 limits for UNS R30003
     

    Question:

    Why does NACE MR0175 / ISO 15156, Part 3 specifically demand age-hardening although age-hardening typically increases the hardness of UNS R30003? Is this because problems were reported when the material was not age-hardened, because data is only available for age-hardened material, or another reason?

    Answer:

    In Table A.39 the cold worked + age hardened condition of UNS R30003 was the only condition originally balloted and accepted.

    This question is in relation to NACE MR0175/ISO 15156-3 Table A.39

    Reference: ISO 15156 Maintenance Panel Inquiry #2009-05

    Contact us to discuss the UNS R30003 NACE MR0175 in the latest revision.

     

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  • 143. Are UNS C72900 and C96900 NACE MR0175 approved?
     

    Because UNS C72900 and C96900 are copper alloys, are they, by definition, covered by NACE MR0175/ISO 15156-3, A.12 which basically states copper alloys are suitable for use without restriction other than as noted in the footnote, which informs the user that such materials may exhibit accelerated general weight-loss corrosion in some sour environments?

    Answer:

    Yes, the UNS C72900 and UNS C96900 copper alloys are included in NACE MR0175/ISO 15156-3, A.12.

    This question is in relation to NACE MR0175/ISO 15156-3 A.12

    Reference: ISO 15156 Maintenance Panel Inquiry #2003-21

     

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  • 144. What are the NACE MR0175 electrode requirements for 625 overlay welding? what about dilution?
     

    Reference: NACE MR0175/ISO 15156-3, Clause A.13.1 (Corrosion-resistant claddings, linings and overlays) The first sentence of Clause A.13.1 states: “The materials listed and defined in Clauses A.2 to A.11 may be used as corrosion-resistant claddings, linings or as weld overlay materials.” The fifth paragraph of Clause A.13.1, as stated below, recognizes that dilution of the weld metal with the substrate occurs during welding. “Dilution of an overlay during application that can impact on its corrosion resistance or mechanical properties should be considered.” Discussion: While the composition of a starting filler metal electrode may meet the composition requirements of an applicable UNS alloy listed in Clause A.2 to A.11, the as-deposited filler metal may be diluted (as noted in the fifth paragraph of A.13.1) to the point where it no longer falls within the applicable UNS alloy’s composition range. For example, a starting electrode for a 625 weld overlay may meet the composition requirements of UNS N00625, but API 6A, 625 overlay made to class FE10 allows an iron content in the as-deposited filler metal of up to 10.0% which exceeds the 5.0% maximum iron limit in UNS 06625. QUESTIONS:

    Q1: Does the as-deposited filler metal have to comply with the UNS composition of the starting electrode?

    ANSWER:

    ISO15156-3 does not state anything specific about the composition of the as-deposited filler metal. It does state that dilution can affect the corrosion resistance. The purpose of an overlay has historically been for corrosion resistance and not cracking resistance. If the enquirer wishes to consider the overlay as a barrier for cracking resistance, a ballot is required to define cracking limits for a specific as deposited composition for a define location within the weld.

    Q2: If the answer to Q1 is yes, then what locations within a weld must meet the UNS composition allowing for some dilution?

    ANSWER:

    This issue is not addressed by this standard. See answer to Q1.

    Q3: Does a 625 overlay made to the prescribed API 6A requirements for FE10 meet NACE MR0175/ISO 15156?

    ANSWER:

    The standard does not define the cracking limits for as-deposited filler material beyond the UNS compositions. See answer to Q1

    This is in relation to NACE MR0175/ISO 15156-3 A.13.1

    Reference: ISO 15156 Maintenance Panel Inquiry #2013-02

    UPDATE 2018-06-04: A recent Technical Circular brings relevant updates on NACE MR0175 and 625 weld overlays: https://oilandgascorrosion.com/nace-mr0175-iso-15156-technical-circulars-for-part-2-and-3-published-2018-06-01/

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  • 145. In NACE MR0175, is GHSC a qualification or production requirement?
     

    Question: Can you confirm our company’s interpretation of the testing described in ANSI/NACE MR0175/ISO 15156-3:2009 Annex B, Section B.8? Our interpretation is that the GHSC testing described in B.8 is for qualification of CRA’s for H2S-service by laboratory testing; this testing in B.8 is qualification testing for including the CRA in the standard and it is not intended to be routine/quality control testing that must be performed on every heat of CRA that is produced at a mill.

    Answer:

    Section B.8 defines the additional requirements/changes to SSC testing for GHSC testing. There is no implied limitation on the application of these tests. The type of tests and the frequency of “periodic” testing to confirm the resistance to cracking for quality control purposes is not defined in ANSI/NACE MR0175/ISO 15156-3 and, these tests, if required, shall be agreed between the manufacturer and the purchaser. The subject of production route qualification is covered in Section B.2.3 “Qualification of a defined production route”.

    This question is in relation to NACE MR0175/ISO 15156-3 Annex B B.8

    Reference: ISO 15156 Maintenance Panel Inquiry #2015-03

     

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  • 146. Is ASTM A 995 Grade 4A (UNS J92205) 22 Cr duplex listed in NACE MR0175?
     

    Question:

    It is our understanding of NACE MR0175/ISO 15156 that provided ASTM A 995 Grade 4A (UNS J92205) 22 Cr duplex stainless steel complies with the material limits of Table A.24 of Annex A, it can be selected for use in H2S-containing environments provided the environmental limits given in Table A.24 are not exceeded.

    Your understanding is correct.

    Reference: ISO 15156 Maintenance Panel Inquiry #2006-04Q1

    Question 2 It does not ALSO have to be listed in Annex D Table D7, which we believe is for information only and lists only SOME duplex stainless steels.

    You are correct.

    This is in relation to NACE MR0175/ISO 15156-3 Annex D

    Reference: ISO 15156 Maintenance Panel Inquiry #2006-04Q2

     

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  • 147. According to NACE, what is the correct chemistry of inconel 625 (UNS N06625)?
     

    Question:

    For the interpretation question of NACE spec MR0175-3, table D.3 Inco 625 alloy chemistry. I believe it is a "typo" but need your concurrence or interpretation if it is not a "typo". Table D.3 as attached below lists Inco 625 chemistry as Nb max weight % 3.15 to 4.15. Typical Inco 625 would have Tantalum in addition to Niobium and typical mill chemistry would specify Nb + Ta as 3.15 % to 4.15 % instead of Nb only. Industry standard spec ASTM B446 chemistry for Inco 625 bars specifies Nb + Ta as 3.15 to 4.15% instead of Nb only. So the question to you (or to NACE) is as follows: 1. Is it a "typo" in the NACE spec and it should be interpreted as Nb + Ta as 3.15% to 4.15% instead of Nb only as specified in the MR0175 spec? 2. If it is not "typo", is there any technical reason why Tantalum would not be accepted as part of standard Inco 625 chemistry?

    Answer:

    1) No. 15156-3 Annex D is an INFORMATIVE annex. ISO 15156 specifies material requirements for specific material groups or UNS numbers. The chemistries of these UNS numbers are established by the international standards organizations that maintain the UNS. Annex D lists chemical composition data using the values and elements defined by UNS. It should be noted that the compositions listed in Annex D have no effect on the NORMATIVE composition limits in Table A.12.

    2) The scope of the MP is limited to interpretation to wording in ISO 15156. The technical reason for tantalum not being included in Annex D for UNS N06625 is, as stated above, the standard adopted the UNS chemistries.

    This question is in relation to NACE MR0175/ISO 15156-3 Table D.3

    Reference: ISO 15156 Maintenance Panel Inquiry #2013-01

     

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  • 148. Is the hardness testing survey required as part of the welding procedure qualification for solid solution nickel-based alloys (as addressed in NACE MR0175/ISO 15156-3, A.4) welded with solid-solution nickel-based weld metal?
     

    Question:

    See A.2.3, MP inquiry #2005-13. This question relates to NACE MR0175/ISO 15156 Part 3, Appendix A, Paragraph A.4.3. Is the hardness testing survey required as part of the welding procedure qualification for solution heat-treated nickel-based alloys welded with solid-solution nickel-based weld metal? In accordance with A.4.3 there are no hardness requirements. A.4.3 Welding solid-solution nickel-based alloys of this materials group. The requirements for the cracking-resistance properties of welds shall apply (see 6.2.2). The hardness of the HAZ after welding shall not exceed the maximum hardness allowed for the base metal, and the hardness of the weld metal shall not exceed the maximum hardness limit of the respective alloy used for the welding consumable. There are no hardness requirements for welding solid-solution nickel-based alloys with solid-solution nickel-based weld metal.

    Answer:

    No.

    This question is in relation to NACE MR0175/ISO 15156-3 A.4.3

    Reference: ISO 15156 Maintenance Panel Inquiry #2006-06

     

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  • 149. What's NACE MR0175 of ferritic stainless steels?
     

    Question:

    NACE MR0175/ISO 15156-3 section A.5.1 and Table D.5, concerning ferritic stainless steels, refer to “some alloys of this type” Given that Table D.5 is stated to not be all-inclusive, can I rightfully construe that any stainless alloy that meets the definition of “ferritic stainless steel” under definition 3.6 can be used under the conditions of Table A.17?

    Answer:

    Yes, any stainless steel that meets the definition of "ferritic stainless steels" under 3.6 can be used under conditions of Table A.17.

    This question is in relation to NACE MR0175/ISO 15156-3 A.5.1

    Reference: ISO 15156 Maintenance Panel Inquiry #2013-10Q1

     

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  • 150. Are free-machining ferritic stainless steels allowed in NACE MR0175?
     

    Question:

    NACE MR0175/ISO 15156-3 sections A.2.1, A.3.1, and A.6.1 each forbid the use of their respective steels in “free-machining” grades. However, this requirement is notably lacking in section A.5.1 regarding ferritic stainless steels. Can I rightfully construe that there is no mistake here, and that free-machining ferritic stainless grades are therefore allowed under the conditions of Table A.17?

    Answer:

    Even though not specifically stated in the current standard, no free machining ferrous alloys including stainless steels are acceptable. This applies also for ferritic stainless steels.

    SUPPLIMENTARY INFORMATION
    A search through historical answers to interpretations has revealed two instances where the interpretation has been that free machining covers all ferrous alloys including stainless steels and these are unacceptable; there have been no interpretations that have permitted the use of free machining steels including ferritic stainless steels. We will investigate wording changes through ballot or editorial means to clarify this.

    This question is in relation to NACE MR0175/ISO 15156-3 A.5.1

    Reference: ISO 15156 Maintenance Panel Inquiry #2013-10Q2

     

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  • 151. Is CA6NM acceptable per MR0175/ISO 15156 at a hardness of max 255 BHN?
     

    Question:My inquiry concerns CA6NM: Earlier editions of the NACE standard contain a note stating that the hardness correlation in ASTM E 140 doesn’t apply to CA6NM and that for this material the maximum permissible value (in Brinell) is 255 BHN. In NACE MR0175/ISO 15156-3, this statement is no longer used. However, Paragraph 7.3.2 of NACE MR01756/ISO 15156-2 stipulates that users can establish hardness correlations for individual materials. Please see below: Quote For ferritic steels EFC Publication 16 shows graphs for the conversion of hardness readings, from Vickers (HV) to Rockwell (HRC) and from Vickers (HV) to Brinell (HBW), derived from the tables of ASTM E 140 and BS 860. Other conversion tables also exist. Users may establish correlations for individual materials. Unquote Finally the questions: Is CA6NM acceptable per MR0175/ISO 15156 at a hardness of max 255 BHN which has been (empirically) determined to be the equivalent of 23 HRC (but which on the ASTM E 140 scale corresponds to about 25 HRC)?

    Answer:

    The prescribed hardness limit of 23 HRC for CA6NM in Table A.18 in NACE MR0175/ISO 15156-3 utilizes the Rockwell C scale as the basis for acceptance. Conversions to other hardness scales are no longer included in the standard. Other hardness scales may still be used provided a correlation can be shown between the scale used and the prescribed Rockwell C scale for the particular material being tested. As stated in Paragraph 6.2.1 of NACE MR0175/ISO 15156-3, conversion between hardness scales is material-dependent. The ISO Maintenance Panel cannot make this conversion for you. The user may establish the required conversion tables.

    This question is in relation to NACE MR0175/ISO 15156-3 A.6.2 Table A.18

    Reference: ISO 15156 Maintenance Panel Inquiry #2004-18 Q1

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  • 152. Does NACE MR0175 allow additional heat treatment for stress relief of CA6NM and F6NM?
     

    Question:

    I have a question regarding NACE MR0175/ISO 15156-3. On Table A.18, the heat treatment requirements for CA6NM and F6NM are listed. Is this the only approved heat treatment? If we follow this heat treatment initially, are other heat treatments allowed as long as they do not exceed the original? We're trying to find out if a supplemental stress relieve is acceptable to try and lower the material hardness.

    Answer:

    Only the heat treatments listed are currently acceptable. Other heat treatments may be qualified in accordance with the requirements of NACE MR0175/ISO 15156-3 Annex B.

    This question is in relation to NACE MR0175/ISO 15156-3 A.6.2. Table A.18

    Reference: ISO 15156 Maintenance Panel Inquiry #2006-19

     

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  • 153. Is UNS J91153 NACE MR0175 approved?
     

    Question:

    In Part 3, A.6.2, Table A.18, under note a) it lists the cast equivalents of the wrought alloys (CA15, CA15M) but under note c) it says cast or wrought S42000 but does not mention the cast equivalent CA40. So, the question is: can I say UNS J91153 is compliant with NACE?

    Answer:

    Early versions of MR0175 did not include UNS S42000 in either the cast or wrought form but S41000 and the cast alloys CA15 and CA15M were included. Wrought S42000 was balloted in 1994. When ISO 15156 was being developed, the statement including "cast or wrought S42000" was added. There was previously a cast version of S42000 (J91201) but that has been withdrawn from the UNS numbering system. Since a cast version of S42000 was never balloted and the casting alloy your inquiry specifies (J91153) is chemically different from S42000, it is not correct to claim that J91153 meets ISO 15156-3. A ballot would be required to change this. See ISO 15156-3 Annex B for CRA testing and balloting guidance. The ballot form is available on the ISO Web site www.iso.org/iso15156maintenance in the document "Introduction to ISO 15156 Maintenance Activities" Annex C.
    A.6.2, Table A.18 and Table A.23

    This question is in relation to NACE MR0175/ISO 15156-3 A.6.2 Table A.18

    Reference: ISO 15156 Maintenance Panel Inquiry #2011-09

     

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  • 154. In NACE MR0175 CRA tables, what's the difference between "any equipment and component" and all the other tables?
     

    Question:

    Inconsistency between Table A.18 and A.23 of Para. A.6.2 in NACE MR0175/ISO 15156-3. Table A.18 allows martensitic stainless steels for any equipment or component, but Table A.23 excludes casing and tubing hanger and valve stems. What is the meaning of any equipment or component? Does any equipment or component from Table A.18 exclude casing and tubing hangers and valve stems?

    Answer:

    No, ISO 15156-3, Tables A.18 and A.23 set different H2S limits for the same selection of martensitic stainless steels. The other environmental limits are the same.
    Table A.18 addresses the use of the materials under the environmental limits of this table. "Any equipment or component" includes wellhead and tree components and valve and choke components, and casing and tubing hangers and valve stems. Table A.23 allows the use of the same selection of materials for wellhead and tree components and valve and choke components under a less restrictive set of environmental conditions but excludes casing and tubing hangers and valve stems under these less restrictive conditions.
    Please see Table 1 of NACE MR0175/ISO15156-3 for the list of equipment covered by this standard and also "General Remarks" under ISO 15156-3, A.1.6 of this "Inquiries and interpretations" document.

    This question is in relation to NACE MR0175/ISO 15156-3  A.6.2, Table A.18 and Table A.23

    Reference: ISO 15156 Maintenance Panel Inquiry 2004-23 Q2

     

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  • 155. About welds, in accordance with NACE MR0175/ISO 15156, Part 2, Item 7.3.3.4, "hardness acceptance criteria for welds," "weld hardness acceptance criteria for steels selected using option 1 (see 7.1) shall be as specified in A.2.1.4. Alternative weld hardness acceptance criteria may be established from successful SSC testing of welded samples. SSC testing shall be in accordance with Annex B." So, in our understanding, if our welding procedure qualifications (WPSs) are qualified in accordance with NACE MR0175/ISO 15156, Part 2, Item A.2.1.4, it is not necessary to test them according to NACE TM0177. We would like you to confirm whether our interpretation below is correct and if not give us the correct interpretation.
     
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    Question:

    About welds, in accordance with NACE MR0175/ISO 15156, Part 2, Item 7.3.3.4, “hardness acceptance criteria for welds,” “weld hardness acceptance criteria for steels selected using option 1 (see 7.1) shall be as specified in A.2.1.4. Alternative weld hardness acceptance criteria may be established from successful SSC testing of welded samples. SSC testing shall be in accordance with Annex B.” So, in our understanding, if our welding procedure qualifications (WPSs) are qualified in accordance with NACE MR0175/ISO 15156, Part 2, Item A.2.1.4, it is not necessary to test them according to NACE TM0177. We would like you to confirm whether our interpretation below is correct and if not give us the correct interpretation.

    Answer:

    Your interpretation is correct.

    Question:

    NACE MR0175/ISO 15156 and NACE TM0177–WELDS
    On the other hand, if we make the test in accordance with NACE TM0177 in our WPSs that are previously qualified to conform to NACE MR0175/ISO 15156, what kind of results will we have? Will we have necessary or redundant results?

    Answer:

    A manufacturer may choose to qualify a welding procedure specification in accordance with ANNEX B. Testing welds acceptable in accordance with A.2.1.4 is an optional activity chosen by the manufacturer to confirm resistance to cracking. This is not necessarily a redundant result depending on the anticipated service conditions and the selected test environment, the results could be used
    -to confirm that the hardness control specified in A.2.1.4 is adequate to prevent sulfide stress cracking
    -or to define alternative weld hardness control requirements that will not lead to sulfide stress cracking when the requirements of A.2.1.4 are not met.

    Reference: ISO 15156 Maintenance Panel Inquiry #2005-08 Q1, Q2 and Q3

    This question is in relation to NACE MR0175/ISO 15156-1 Clause 7

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  • 156. What is a NACE MR0175 material?
     

     

    What is a NACE material? What is NACE piping? What is a NACE MR0175 compliant steel? Where is the definite list of NACE MR0175 compliant materials?

    NACE is the National Association of Corrosion Engineers, NACE publishes many documents related to corrosion control including NACE MR0175 which provides the requirements for metallic materials exposed to H2S in oil and gas production environments.

    NACE MR0175 lists the requirements for carbon steels, low alloys and corrosion resistant alloys.  For each material group, NACE MR0175 provides the following metallurgical requirements:

    • Chemistry
    • Hardness
    • Heat treatment
    • HIC resistance etc

    NACE MR0175 also provides the environment limits i.e, amount of H2S expressed as partial pressure, the maximum chloride content, pH range etc.

    A NACE MR0175 compliant material (sometimes inaccurately referred to as NACE material or NACE piping) is a material that meets all the requirements of NACE MR0175 and can be used in H2S environments within the limits set by the standard.

    It is extremely important to say: Hardness below 22HRC is required for some materials but it is not the only NACE MR0175 requirement.

    Our team can help you answer the following questions:

    • What are the NACE MR0175 requirements for a specific material?
    • The MTR does not state "NACE compliant", is the material ok?
    • What's the minimum ppm of H2S for "NACE material"?
    • How to specify "NACE material"? Is HIC required?
    • Is there a list of NACE MR0175 approved materials?
    • Where are the NACE material checklists?

    Our team of metallurgist can help you to specify and select materials that are fully compliant with NACE MR0175.

    Talk to our team today!

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    Contact us to find out more. In the US call our toll-free number 877.399.1010 and in the UK call 0114 4000850; or use our webchat for online materials and corrosion support.

    Oil and Gas Corrosion Ltd is an independent materials and corrosion consultancy for the Oil and Gas industry. Oil and Gas Corrosion Ltd is under the guidance of Ivan Gutierrez. Ivan has more than 20 years’ experience in materials and corrosion and is a member of the National Association of Corrosion Engineers (NACE), a professional member of the Institute of Corrosion (MICorr) and the Society of Petroleum Engineers (SPE). He is a recognised materials and corrosion authority recognised as a Great Britain national expert member of the British Standard Institution committee PSE/17/67/7 "Corrosion Resistant Materials" and internationally as a member of Task Group 299 on the Oversight of Maintenance Panel for NACE MR0175 / ISO 15156. “Materials for use in H2S-containing environments in oil and gas production”, IOGP 15156 Committe (ISO/TC 67/WG 7 "Corrosion Resistant Materials". Ivan is also a member of ISO/TC 67/WG 8 Materials, corrosion control, welding and jointing, and non-destructive examination (NDE) which is responsible for standards such as ISO 21457 "Materials selection and corrosion control for oil and gas production systems".Oil & Gas Corrosion has headquarters in the United Kingdom providing services to clients across the globe.

     

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  • 157. The material certificate states NACE MR0175 2009, does it meet NACE MR0175 2015?
     

     

    There are several changes from NACE MR0175 2009 to NACE MR0175 2015, you can find a list of changes in this article.

    There is no definite answer for this question, material and equipment certified to NACE MR0175 2009 in some instances comply with the requirements of NACE MR0175 2015. each Material Test Certificate (MTC) also referred to as Material Test Report (MTR)  needs to be reviewed against the requirements of ANSI/NACE MR0175/ISO15156 2015.

    It is also very important to remember that the production environmental limits for some alloys have changed from NACE MR0175 2009 to NACE Mr0175 2015 and users must keep this in mind.

    At Oil & Gas Corrosion we can assist you to determine if a Material Test Certificate (MTC) also referred to as Material Test Report (MTR) meets the requirements of NACE MR0175 2015. Contact our team today

     

    With a wealth of experience in the oil and gas industry, we provide independent materials and corrosion consultancy to help companies reduce risk, save money and apply best practice in their oil and gas businesses.

    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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  • 158. What is sour service?
     

    What is sour service?

    Sour service is referred to exploration and production environments in oil and gas that have enough H2S that could cause cracking of metallic materials.

    H2S (hydrogen sulphide) H2S is a highly flammable, explosive gas, and can cause possible life-threatening situations if not properly handled. H2S is deadly even at very low concentrations. Government regulators, health and safety bodies and industry associations across the world stressed this out. Short time exposures to concentrations as low as 100ppm (parts per million) of H2S can have deadly consequences Immediately Dangerous to Life and Health. In the UK H2S has a 10 ppm per 15-minute time weight averaged

    The oil and gas industry recognise sour service as one of the toughest challenges in hydrocarbon production. H2Scracking is a risk to the integrity of assets and operations,
    Industry bodies including API and IOGP as well as national and international codes likes ANSI, EN and ISO recognise NACE MR0175 as a standard to prevent H2S cracking in metallic materials. The Code of Federal Regulations as well as UK Health and Safety Executive refer to NACE MR0175 as a method to prevent cracking of metallic materials exposed to H2S.

    NACE MR0175 is an international standard that provides the requirements for metallic materials exposed to H2S in oil and gas production environments. NACE MR0175 is identical to ISO 15156. ANSI / NACE MR0175 / ISO 15156 lists the requirements for carbon steels, low alloys and corrosion resistant alloys.

    NACE MR0175 defines sour service as “Exposure to oilfield environments that contain sufficientH2S to cause cracking of materials by the mechanisms addressed by NACE MR0175/ISO 15156.”

    The team at Oil and Gas Corrosion Ltd. can help you develop and implement H2S management strategies. Talk to us today!

     

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    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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  • 159. What is the NACE MR0175 heat treatment?
     

    What is the NACE MR0175 heat treatment?

    NACE MR0175 is an international standard that provides the requirements for metallic materials exposed to H2S in oil and gas production environments. These requirements include:

    • Chemistry
    • Heat treatment form
    • Hardness
    • Microstructure (in some cases)
    • HIC resistance.
    • NACE MR0175 has specific heat treatment requirements for carbon steel and low alloy steels, NACE MR0175 also has specific heat treatment requirements for corrosion resistant alloys.

    NACE MR0175 defines heat treatment as heating and cooling of a solid metal or alloy in such a way as to obtain desired properties, hot working is not considered heat treatment. Heat treatment is an important requirement that has a direct impact on the metallic material resistance to H2S damaging mechanisms such as sulphide stress cracking (SSC), stress corrosion cracking (SCC) and other related cracking mechanisms.

    When a material that does not comply with the NACE MR0175 heat treatment requirement is exposed to H2S, catastrophic failure can take place.

    Oil and Gas Corrosion Ltd. has a team of expert metallurgists that can help you identify the NACE MR0175 heat treatment requirements and make sure the materials used in your project comply with these requirements.

    Talk to our team today!

     

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    Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

     

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  • 160. Which corrosion resistant alloy cladding complies with NACE MR0175?
     

     

    Which corrosion resistant alloy cladding complies with NACE MR0175?

    NACE MR0175 is an international standard that provides the requirements for metallic materials exposed to H2S in oil and gas production environments. ANSI / NACE MR0175 / ISO 15156 provides the requirements for corrosion resistant claddings and linings. These requirements may include:

    • Requirements for corrosion resistant alloy (CRA) cladding and linings
      • Chemistry
      • Heat treatment condition
      • Microstructure
      • Corrosion testing
      • Welding requirements for overlay weld deposition
      • Dilution requirements
    • Requirements for base material (carbon steel in most cases)
      • Chemistry
      • Heat treatment form
      • Hardness
      • HIC resistance

    A material used in upstream hydrocarbon production that is cladded or lined with CRA and is exposed to H2S must comply with NACE MR0175. If the classing (or lining) does not meet the requirements, or if the base material is susceptible to H2S related damage mechanisms, the equipment can have a catastrophic failure leading to H2S release to the environment.

    Oil and Gas Corrosion Ltd. has a team of expert metallurgists that can help you identify the NACE MR0175 requirements for corrosion resistant alloys cladding and linings as well as base materials. Our team can help you make sure fabrication of pressure vessels and pipelines that use CRA cladded materials comply with statutory requirements and NACE MR0175

    Talk to our team today!

     

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  • 161. What is NACE bolting?
     

     

    What is NACE bolting?

    NACE bolting is a term used for bolts that are in compliance with NACE MR0175. NACE MR0175 is an international standard that provides the requirements for metallic materials exposed to H2S in oil and gas production environments. NACE MR0175 is identical to ISO 15156. ANSI / NACE MR0175 / ISO 15156 lists the requirements for carbon steels, low alloys and corrosion resistant alloy exposed to H2S in oil and gas exploration and production environments.

    Bolt compliance to NACE MR0175 sometimes can be confusing confusion, for example flange bolts are not in direct contact with the transport fluids, however a leak may expose them to H2S. NACE MR0175 / ISO 15156 -2 section A.2.2.4 addresses this matter by stating “Bolting that can be exposed directly to a sour environment, or that is buried, insulated, equipped with flange protectors or otherwise denied direct atmospheric exposure or direct open seawater exposure, shall conform to the general requirements of A.2.1.”

    Our team of metallurgists can help you select the correct bolting material for your project.

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  • 162. What is the NACE MR0175 latest edition?
     

    What is the NACE MR0175 latest edition?

    NACE MR0175 is an international standard that provides the requirements for metallic materials exposed to H2S in oil and gas production environments.
    NACE MR0175 is identical to ISO 15156. ANSI / NACE MR0175 / ISO 15156 lists the requirements for carbon steels, low alloys and corrosion resistant alloy exposed to H2S in oil and gas exploration and production environments.

    The latest edition is 2015, this third edition issued in 2015 cancels and replaces the second edition of 2009. ANSI / NACE MR0175 / ISO 15156 was fully updated in all three parts.

    NACE MR0175 is continuously updated via Technical Circulars. To find out the latest Technical Circulars you can visit our NACE MR0175 tracker

     

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  • 163. What is the NACE MR0175/ISO 15156 revision history?
     

     

    What is the NACE MR0175/ISO 15156 revision history?

    NACE MR0175 is an international standard that provides the requirements for metallic materials exposed to H2S in oil and gas production environments.

    NACE MR0175 is identical to ISO 15156. ANSI / NACE MR0175 / ISO 15156 lists the requirements for carbon steels, low alloys and corrosion resistant alloy exposed to H2S in oil and gas exploration and production environments.

    This is the ANSI / NACE MR0175 / ISO 15156 revision history

    • NACE MR0175 / ISO 15156-2:2003 (Status: Revised,Withdrawn)
    • NACE MR0175 / ISO 15156-2:2009 (Status: Revised,Withdrawn)
    • NACE MR0175 / ISO 15156-2:2015 (Status: Current – with technical circulars)

    To keep up with the latest NACE MR0175 version and the technical circulars visit our NACE MR0175 tracker: https://oilandgascorrosion.com/nace-mr0175-latest-edition/

     

     

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  • 164. What are the NACE MR0175 marking requirements?
     

     

    What are the NACE MR0175 marking requirements?

    NACE MR0175 is an international standard that provides the requirements for metallic materials exposed to H2S in oil and gas production environments.

    NACE MR0175 is identical to ISO 15156. ANSI / NACE MR0175 / ISO 15156 lists the requirements for carbon steels, low alloys and corrosion resistant alloy exposed to H2S in oil and gas exploration and production environments.

    NACE Mr0175 in Part 2 Clause 9 requires compliant materials to be traceable, preferably by marking. It is important that any identification stamping is low-stress type (e.g. dot- vibratory and round V). Marking on high stress areas should be avoided. For carbon and low alloy steel, NACE MR0175 Part 2 Annex E (informative) provides examples of designations that may be used to identify materials. For CRAs you can find examples of designations for marking in NACE MR0175 Part 3 Annex C

    Our team can help you define suitable marking and identification methods for raw material and equipment in compliance with NACE MR0175.

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  • 165. NACE MR0175/ISO 15156 and NACE TM0177--WELDS On the other hand, if we make the test in accordance with NACE TM0177 in our WPSs that are previously qualified to conform to NACE MR0175/ISO 15156, what kind of results will we have? Will we have necessary or redundant results?
     
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    Question:

    About welds, in accordance with NACE MR0175/ISO 15156, Part 2, Item 7.3.3.4, “hardness acceptance criteria for welds,” “weld hardness acceptance criteria for steels selected using option 1 (see 7.1) shall be as specified in A.2.1.4. Alternative weld hardness acceptance criteria may be established from successful SSC testing of welded samples. SSC testing shall be in accordance with Annex B.” So, in our understanding, if our welding procedure qualifications (WPSs) are qualified in accordance with NACE MR0175/ISO 15156, Part 2, Item A.2.1.4, it is not necessary to test them according to NACE TM0177. We would like you to confirm whether our interpretation below is correct and if not give us the correct interpretation.

    Answer:

    Your interpretation is correct.

    Question:

    NACE MR0175/ISO 15156 and NACE TM0177–WELDS
    On the other hand, if we make the test in accordance with NACE TM0177 in our WPSs that are previously qualified to conform to NACE MR0175/ISO 15156, what kind of results will we have? Will we have necessary or redundant results?

    Answer:

    A manufacturer may choose to qualify a welding procedure specification in accordance with ANNEX B. Testing welds acceptable in accordance with A.2.1.4 is an optional activity chosen by the manufacturer to confirm resistance to cracking. This is not necessarily a redundant result depending on the anticipated service conditions and the selected test environment, the results could be used
    -to confirm that the hardness control specified in A.2.1.4 is adequate to prevent sulfide stress cracking
    -or to define alternative weld hardness control requirements that will not lead to sulfide stress cracking when the requirements of A.2.1.4 are not met.

    Reference: ISO 15156 Maintenance Panel Inquiry #2005-08 Q1, Q2 and Q3

    This question is in relation to NACE MR0175/ISO 15156-1 Clause 7

    At Oil & Gas Corrosion we can resolve your queries in welding procedures and qualifications to meet NACE MR0175.

     

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  • 166. Do NACE MR0175/ISO 15156-2, 7.3.2 “Parent metals” and NACE MR0175/ISO 15156-3, 6.2.1 “Hardness of parent metals” apply to machined forgings or are they meant to be applied to weldment parent metals only?
     
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    Question: Do NACE MR0175/ISO 15156-2, 7.3.2 “Parent metals” and NACE MR0175/ISO 15156-3, 6.2.1 “Hardness of parent metals” apply to machined forgings or are they meant to be applied to weldment parent metals only?

    Answer:

    The requirements listed in NACE MR0175/ISO 15156-2 Section 7.3.2 apply to the parent materials applicable to part 2; carbon and low alloy steels and cast irons. The parent materials include forgings. See also sections A.2.1.2 and A.2.1.3 of Annex A for additional requirements. The requirements listed in NACE MR0175/ISO 15156-3 Section 6.2.1 apply to parent materials applicable to part 2; CRAs and other alloys. The parent materials include forgings

    This question is in relation to NACE MR0175/ISO 15156-3 Clause 6.2.1

    Reference: ISO 15156 Maintenance Panel Inquiry #2014-03

     

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  • 167. For NACE MR0175 compliant products, is Carburizing is an acceptable surface treatment process?
     

    Carburizing is not currently permitted in ISO 15156 except in conjunction with the permitted exclusions in Table 1 of ISO 15156-2. These exclusions are associated with specific equipment that is loaded in compression and equipment that is outside the scope of ISO 15156.

    This question is in relation to NACE MR0175/ISO 15156-3 Annex A.1.5.1

    Reference: ISO 15156 Maintenance Panel Inquiry #2013-04Q1

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  • 168. If Carburizing is not considered the same as Nitriding in paragraph A. 2.1.5, is it acceptable to have carburized surface treatment (where the surface hardness will be well over HRC 22 hardness) but the core to meet the maximum average hardness of 22 HRC?
     

    Carburizing is not permitted regardless of core hardness except as noted in Q1.

    This question is in relation to NACE MR0175/ISO 15156-3 Annex A.1.5.1

    Reference: ISO 15156 Maintenance Panel Inquiry #2013-04Q2

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  • 169. If Carburizing is acceptable surface treatment method, can the max hardness (HRC 22) and Nickel content (max 1%) of the core of carburized part be allowed to be higher than what NACE MR0175 allows?
     

    Not applicable.

    This question is in relation to NACE MR0175/ISO 15156-3 Annex A.1.5.1

    Reference: ISO 15156 Maintenance Panel Inquiry #2013-04Q3

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  • 170. Is NACE MR0175 used only for sour service?
     

    Is NACE MR0175 used only for sour service?

    NACE MR0175 is an international standard that provides the requirements for metallic materials exposed to H2S in oil and gas production environments. NACE MR0175 is identical to ISO 15156. ANSI / NACE MR0175 / ISO 15156 lists the requirements for carbon steels, low alloys and corrosion resistant alloy exposed to H2S in oil and gas exploration and production environments.

    NACE MR0175 defines sour service as “Exposure to oilfield environments that contain sufficientH2S to cause cracking of materials by the mechanisms addressed by NACE MR0175/ISO 15156”.

    If your production environment is not at immediate risk of H2S exposure, then NACE MR0175 may be applicable. To get expert advice talk to our team, our experts in sour service will help you determine the requirements for your project.

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    • 171. What are the sour service limits for UNS N08029?
       

       

      UNS N08029 seamless tube is specified in ASTM B668-14. According to ISO 15156-3 Table A.12, UNS N08029 belongs to materials type 4c. However the material is not included in ISO 15156-3 2015 Annex D, Table D.3 - Chemical compositions of some solid-solution nickel-based alloys. Based on our testing using constant load and SSR (at least duplicate specimens), this material passed the tests in the sour environments outside of the limit for material type 4c.

      Question 1: What would be done in order to include UNS N08029 in standard ISO 15156-3, Annex D, Table D.3?

      Question 2: We are thinking of additional testing, to propose new limit through NACE Ballot. Are the data points "A" and "B" enough for extending the acceptable limit to the yellow area in the attached figure?

      Question 3: Is one of the testing methods enough to propose the new limit, using constant load or SSR per NACE TM0177 or MR0198?

      Question 4: Is 1 g/l sulfur ok to represent the environment with elemental sulfur?

      Answer 1: Table D.3 is an informative table and adding a material that complies with type 4c is not a technical change. This can be added to the document at the next opportunity or Technical Circular at your request once a formal request for the editorial change is submitted.

      Answer 2: Please refer to 15156-3 Annex B especially B.2.4. To extend the limits, you will need test data (in accordance to B.3 and for applicable cracking mechanisms in Table B.1) from a minimum of three separately processed heats. Since the alloy is cold worked to achieve mechanical properties note that B.3.2.c states that the following shall be considered “the directional properties of alloys because cold-worked alloys may be anisotropic with respect to yield strength and for some alloys and products, the susceptibility to cracking varies with the direction of the applied tensile stress and consequent orientation of the crack plane”.

      Answer 3: Please refer to B.3.3. Generally, constant load tests are preferred for homogeneous materials. For constant load and constant displacement (constant deformation) tests, a test duration between 90 and 180 days should be considered. You can augment the data with SSRT test results.

      Answer 4: This has been one of subjects recently discussed in the Maintenance Panel. The requirements for testing with elemental sulphur have not been fully defined but use of 1 g/L S0 is severely limiting. Please see NACE Corrosion 1995, Paper 47 for more details and guidance as to the appropriate methodology which will depend on the expected physical state of the elemental sulfur for the application conditions.

      Reference: Maintenance Panel 2016-14 and is in relation to NACE MR0175 part 3, table D.3

      If you require further information on the sour service limits of UNS 08029 contact our team through our webchat. We are here to help

       

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    • 172. Inconel X750 (UNS N07750),can it be used for sour service?
       

       

      Inconel X750 (UNS N07750) is a precipitation hardened nickel based alloy that is listed in NACE MR0175 / ISO 151656 part 3tables A.35 and A.36 as a valid material for non-pressure containing components and springs.
      This material was previously listed in NACE MR0175-2002 as an approved Nickel-Chromium alloy. It is still listed in NACE MR0103 as an approved precipitation-hardenable Nickel alloy.

      a) Is the correct interpretation that this material is prohibited from use as a pressure boundary component for any NACE MR0175 application under any conditions?

      b) If yes, can you provide any explanation for why it was removed? Was there testing or a ballot submittal to justify its exclusion?

      Question 1: Is the correct interpretation that this material is prohibited from use as a pressure boundary component for any NACE MR0175 application under any conditions?

      Answer: Yes, that is the correct interpretation.

      Question 2: If yes, can you provide any explanation for why it was removed? Was there testing or a ballot submittal to justify its exclusion?

      Answer: The alloy was removed in the NACE MR0175 2003 rewrite and this was carried over in NACE MR0175/ISO 15156 in 2003. We cannot provide a definitive answer as to why it was removed but we know that the alloy is susceptible to hydrogen embrittlement and there have been some failures with the alloy. Please review the subject in “H2S Corrosion in Oil & Gas Production: A Compilation of Classic Papers, NACE, 1981” and NACE Corrosion 2003 conference paper 03133.

      Reference: Maintenance Panel Inquiry #2015-15 and in reference to NACE MR0175 part 3 A.9

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    • 173. NACE MR0175 and the heat treatment of Inconel X750
       

       

      Based on NACE paper 03133, the cause of failure of UNS N07750 was identified as sensitization of the material when it was exposed to a temperature of around 2000⁰F and cooled slowly. The paper points to the lack of defined quality control procedures, specifically the definition of Solution Heat Treatment. This no longer seems to be the case as Table A.27 of NACE MR0175-3 lists very specific heat treating process requirements for UNS S17400.
      If the heat treatment of UNS N07750 were properly controlled per a well-defined standard such as AMS 5667, would this material be acceptable for qualification by lab testing or field experience?

      Or are there additional causes to doubt this materials ability to resist hydrogen embrittlement or SSC?

      ANSWER:

      Question 1: If the heat treatment of UNS N07750 were properly controlled per a well-defined standard such as AMS 5667, would this material be acceptable for qualification by lab testing or field experience?
      Please review , Clause 6.1 of ISO 15156-3. You may test in accordance with Annex B of ISO 15156-3 and, with successful tests, the alloy would be acceptable for use with the agreement of the end-user for the application. The documentation requirements for these tests shall be in accordance with ISO 15156-1 Clause 9. You may also use field experience noting the requirements of ISO 15156-1 Clause 8.2 with the documentation requirements of Clause 9.
      NACE Corrosion 2003 Conference Paper 03133 demonstrated a sensitization of X750 alloy at grain boundaries as the root cause of embrittlement. Question 2: are there additional causes to doubt this materials ability to resist hydrogen embrittlement or SSC?

      There are known cases of embrittlement in this alloy due to hydrogen charging. We do not know whether some or all the reported instances were due to sensitization.

      Reference: MP INQUIRY #2016-16 (Ref NACE MR0175 part 3 A.8.2, Table A.27)

      Contact us to discuss the use of Inconel X750 in sour service.

       

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    • 174. Cold forming (rolling) of threads and NACE MR0175
       

       

      ISO 15156-3:2015 says about threading:
      A.1.5.2 Threading
      Threads produced using a machine-cutting process are acceptable.
      Threads produced by cold forming (rolling) are acceptable on CRAs and other alloys if the material and the limits of its application otherwise comply with this part of ISO 15156.
      Is the meaning:
      a) it is acceptable in general to use a material that comply with the ISO 15156 series and produce a thread by cold forming with the material
      or
      b) specific tests are required on the thread produced by cold forming. If yes, which specifications and which threshold values shall be used?

      Answer:

      a) it is acceptable in general to use a material that comply with the ISO 15156 series and produce a thread by cold forming with the material.
      Answer: Threads produced by cold forming are acceptable as long as the final threaded product meets the requirements, including chemical composition mechanical properties, etc.) of the specific material (employed for its manufacture) as described in ISO 15156-3:2015

      b) specific tests are required on the thread produced by cold forming. If yes, which specifications and which threshold values shall be used?
      Answer: Qualification of CRA materials (including manufactured products) that do not meet the requirements of ISO 15156-3:2015 shall be done per ISO 15156-3:2015 Annex B. It is the manufacturer responsibility (in close collaboration with the end user) to define a suitable testing plan to ensure that the final manufactured product is appropriate and fit-for-purpose for the intended sour service application.

      Contact our team for technical support with NACE MR0175 compliance of threads and bolts.

       

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    • 175. Water handling facilities and the exceptions in NACE MR0175 / ISO 15156
       

      ISO 15156 Table 1 provides a non-exhaustive list of equipment to which this part of ISO 15156 is applicable, including permitted exclusions. Among the exclusions are :

      1. “Water-handling facilities operating at a total absolute pressure below 0,45 MPa (65 psi)” .
        Q1. What are the fundamentals of such exclusions in this standard?
        Q2. Can they be ALWAYS excluded independently of the H2S amount, HCN, pH, material strength, etc.?
        Question comes because HIC damage could be present regardless of the pressure. Also SSC might be expected in the Welds/HAZ in not PWHT CS at H2S >670ppm and 65 psi (sour service).
        There is a perceived danger with this interpretation, as the current tendency to minimize H2S flaring and to comply with the environmental regulations is to by-pass the H2S scrubbers moving the waste water from a non-sour service in the original design (<50 ppm H2S) to sour service ranges (up to 1000 ppm H2S). Because the standard doesn’t establish any boundary, it looks acceptable to do so.
      2.  “Water injection and water disposal equipment” .
        Q3. Usually the water injection works at a very high pressure (i.e. 90 bars in our facilities and original design 50 ppm H2S). Such case is already considered sour service (PpH2S>0.3 kPa). What are the fundamentals to permit exclusions under this standard then?

      ANSWER:
      ISO 15156 Table 1 provides a non-exhaustive list of equipment to which this part of ISO 15156 is applicable, including permitted exclusions. Among the exclusions are “Water-handling facilities operating at a total absolute pressure below 0,45 MPa (65 psi)”.
      Question 1: What are the fundaments of such exclusions in this standard?
      Answer 1: The exclusions are historical and based on successful applications over many decades.
      Question 2: Can they be ALWAYS excluded independently of the H2S amount, HCN, pH, material strength, etc.?
      Answer 2: Table 1 of NACE MR0175/ISO 15156 does not impose any limits on the equipment with permitted exclusions unless otherwise noted at the bottom of Table 1.
      Question 3: Usually the water injection works at a very high pressure (i.e. 90 bars in our facilities and original design 50 ppm H2S). Such case is already considered sour service (pPH2S>0.3 kPa). What are the fundamentals to permit exclusions under this standard then?
      Answer 3: The User has the responsibility to ensure that materials selected are suitable for the intended service (see Warning paragraph under Part 1: General principles for selection of cracking-resistant materials). You have the responsibility to determine whether your application is safe under intended service conditions; you may wish to employ a consultant to assist you in your evaluation.

      Reference: Maintenance Panel inquiry 2016-18 (NACE MR0175-2 Table 1)

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    • 176. Cold work of dual certified 316/316L and NACE MR0175
       

      1. Under Table A.2 – ‘Environmental and materials limits for austenitic stainless steels used for any equipment or components’, in the notes section under the sub heading ‘b’, which apply to grade UNS S31603 (316L), is the following statement ‘the material shall be free from cold work caused by shaping, forming, cold reducing, tension, expansion, etc. after the final solution annealing and quenching treatment. My question is, why is this statement also not applicable to other types of austenitic stainless steels described in paragraph A.2 (under sub heading ‘a’ above)?
      2. Following on from question 1 above, if a material is dual certified as 316/316L (UNS S31600/S31603), what category of Table A.2 will it be designated under? i.e. will it be deemed under category A.2 (note ‘a’) or as UNS S31603 (note ‘b’)? Or both?
      (MP INQUIRY #2016-19)
      ANSWER:
      Under ISO 15156-3 Table A.2, in the notes section under the sub heading ‘b’, which apply to grade UNS S31603 (316L), is the following statement ‘the material shall be free from cold work caused by shaping, forming, cold reducing, tension, expansion, etc. after the final solution annealing and quenching treatment.
      Question 1: Why is this statement also not applicable to other types of austenitic stainless steels described in paragraph A.2 (under sub heading ‘a’ above)?
      Answer: The words present in note “b” are in accordance with a successful ballot to extend the use limits of UNS S31603. The extension of these use limits was accompanied by a more descriptive definition of what constitutes cold work.
      Question 2: If a material is dual certified as 316/316L (UNS S31600/S31603), what category of ISO 15156-3 Table A.2 will it be designated under?
      Answer: The alloy meets and applies to both “a” and “b” as applicable. Note the paragraph in ISO 15156-3 Clause A.2.1 which states “It is common industry practice to dual certify 300 series stainless steels as standard grade and low carbon grade such as S31600 (316) and S31603 (316L). The environmental limits given for low carbon 300 series stainless steels are acceptable for the dual certified grades”.

      Reference: Maintenance Panel inquiry 2016-19 (NACE MR0175 Part 3 Clause A.2)

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    • 177. What are the NACE MR0175 hardness requirements for LF2?
       

       

      Question: Kindly clarify does NACE MR-0175/ISO 15156 specifies the Hardness requirement for ASTM A350 Grade LF2 material.

      Answer:

      NACE MR0175/ISO 15156 does not dictate the hardness requirements that may be present in other standards. The standard does define material requirements and use limits as they relate to environmental cracking in the presence of H2S. ASTM A350 LF2 requires the hardness to be 197 HB maximum and this meets the requirements for carbon steel forgings in NACE MR0175/ISO 15156-2. Please refer to Clause A.2.1 and the sub-clauses beneath it for carbon and low alloy steels.

      Reference MP Inquiry 2017-01 (NACE MR0175 Part 2 Scope)

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    • 178. What are the NACE MR0175 limits for ferritic ductile iron ASTM A395?
       

      Question 1: Section A.2.4.1, part 2 (ANSI/NACE MR0175/ISO 15156-2:2015) states “Ferritic ductile iron in accordance with ASTM A395 is acceptable for equipment unless otherwise specified by the equipment standard” - does this imply that its use is acceptable for pressure-containing parts?
      Question 2: Are there any partial pressure limits that would apply to using ferritic ductile iron in accordance with ASTM A395?
      Answer 1:

      There is no restriction in ANSI/NACE MR0175/ISO 15156-2 regarding using ferritic ductile iron in accordance with ASTM A395 for pressure containing components. Note that there may be restrictions on using this material from other standards such as API standards that are outside the scope of ANSI/NACE MR0175/ISO 15156-2.

      Answer 2:

      There are no partial pressure limits with respect to H2S for cast irons but note the warning that precedes the Scope of ANSI/NACE MR0175/ISO 15156-2. This warning states: Carbon and low-alloy steels and cast irons selected using this part of ISO 15156 are resistant to cracking in defined — H2S-containing environments in oil and gas production but not necessarily immune to cracking under all service conditions. It is the equipment user’s responsibility to select the carbon and low alloy steels and cast irons suitable for the intended service.

      Reference: MP Inquiry 2017-02 (NACE MR0175 Part 2 A.2.4.1)

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    • 179. Is cold-finishing be acceptable for an annealed material that is limited to 22 HRC max hardness?
       

       

      Section A.1.5.3 of ANSI/NACE MR0175/ISO 15156-3:2015 states “Cold deformation of surfaces is acceptable if caused by processes such as burnishing that do not impart more cold work than that incidental to normal machining operations (such as turning or boring, rolling, threading, drilling, etc.).” - Would cold-finishing be acceptable for an annealed material that is limited to 22 HRC max hardness?

      Answer:
      Cold finishing is acceptable only if the cold work is no more than that that would be incidental to normal machining operations. The hardness restrictions for the material remain as specified in ANSI/NACE MR0175/ISO 15156-3:2015.

      Reference: Mp Inquiry 2017-03 (NACE MR0175 Part 3 A.1.5.3.

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    • 180. What are the NACE MR0175 requirements for UNS S66220 and UNS S66286?
       

      QUESTION:
      Material S66286 may be used according Table A.26. In the note is written “UNS S66286 shall have a maximum hardness of 35 HRC and shall be in either the solution-annealed and aged or solution-annealed and double-aged condition.”.
      According ASTM A638 and ASTM A453 is Grade 660 UNS S66286 and Grade 662 UNS S66220. But the heat treatment differs:
      (UNS S66286) ASTM A638 Grade 660 type 1 and 2 Heat treatment: solution-annealed and aged, see ASTM A638 Table 3
      ASTM A453 Grade A and B Heat treatment: solution-annealed and aged, see ASTM A453Table 4
      ASTM A453 Grade C and D Heat treatment: solution-annealed and double aged condition, see ASTM A453Table 4
      (UNS S66220) ASTM A638 Grade 662 Heat treatment: solution-annealed and double aged condition, see ASTM A638 Table 3
      ASTM A453 Grade 662 A and B Heat treatment: solution-annealed and aged, see ASTM A453Table 4

      Question 1: Regarding UNS S66286 and 15156-3 Table A.26, does this Table apply to bolting (ASTM A453) and bar (ASTM A638) materials?
      Answer 1: The Table has no restrictions on product form. UNS S66286 is required by Table A.26 to be in the solution annealed and aged or solution annealed and double aged condition with a maximum hardness of 35 HRC.
      Question 2: If ASTM A638 is included in 15156-3 Table A.26, then is UNS S66220 (Grade 662) also included in Table A.26.
      Answer 2: 15156-3 Table A.26 only applies to UNS S66286; this Table does not include UNS S66220.

      Reference MP Inquiry 2017-04 (NACE MR0175 Part 3 A.8 Table A.26

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    • 181. Welding UNS S31603 and NACE MR0175, welds need to be solution annealed and quenched again?
       

      NACE MR0175/ISO15156 Table A.2 footnote (b) states that UNS S31603 shall be in the solution-annealed and quenched condition.
      Question: Do welds need to be solution annealed after welding if the base metals were all solution annealed and the filler metal is of an ER/E316L type?
      The operating condition is around 1000 psig at 80F. The H2S partial pressure is 40 psi, chloride content around 2000 ppm, pH around 4.85.
      Question 1: Regarding UNS S31603 and 15156-3 Table A.2 Footnote (b), this footnote states that the UNS S31603 shall be in the solution annealed and quenched condition. Do welds need to solution anneal after welding if the base metals were all solution annealed and the filler metal is of the E/ER316L type? The operating condition is 1000 psig at 80F with 40 psi partial pressure H2S, 2000 ppm chloride and pH about 4.5.

      Answer 1:

      The 15156-3 Table A.2 does not specifically address the requirements for weldments. Note Clause 6.2.2.1 that states that “the metallurgical changes that occur when welding CRAs and other alloys can affect their susceptibility to SSC, SCC and/or GHSC. Welded joints can have greater susceptibility to cracking than the parent material(s) joined.” The required documented evidence for welding PQRs is defined in Clause 6.2.2 sub-clauses. You may want to employ a consultant to assist you with your application.

      Reference MP Inquiry 2017-05 NACE MR0175 Part 3 A.2

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    • 182. What are the chloride limits for UNS S31600 and UNS 31603?
       

      Chloride con column is "see remark"- which is any combination of chloride concentration and in situ pH occurring in production is acceptable.
      E.G. TABLE A.2, S31600 can resist 5000 mg/h Chloride concentration??
      How to understand these figures? or they are same service, means
      5000 mg/l is only valid for temp less than 93 oc, PH2S less than 10.2 kPa???

      Q1: Regarding 15156-2 Table A.2 for UNS S31600, the remarks section defines acceptance for any chloride and in situ pH. Can UNS S31600 be acceptable with a chloride content of 5000 mg/L?

      A1: Table A.2 permits any level of chloride for austenitic stainless steels defined in Clause A.2 with the following restrictions: temperature shall be no higher than 60°C, the partial pressure of H2S shall be no higher than 100 kPa and no elemental sulfur. Note that the material restrictions defined in note a in Table A.2 also apply.

      Q2: How do I understand these figures in Table A.2?

      A2: We cannot provide consulting services. You may need to employ a consultant to help your understanding of these material and application limits.

      Reference MP Inquiry 2017-06 (NACE MR0175 Part 3 A.2)

      Our team of metallurgists and corrosion specialists can help you with the interpretation and implementation of the NACE MR0175 requirements. We have experience dealing with chlorides, pH and ppH2S requirements. Contact us today to find the answers you are urgently requiring.

       

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    • 183. Is there a Fahrenheit to Centigrade discrepancy in NACE MR0175?
       

      The age hardening temperature midpoint in Centigrade for UNS S17400 and UNS S15500 in Tables A.27, A.28, A.29 and A.30 is 620 C; should be 621 C.
      NACE MR0175-3 2015
      In Centigrade, 634 °C max.
      For comparison, NACE MR0103-2015:
      In Centigrade, 635 °C max.
      I believe the intent is to adhere to the Fahrenheit range of 1125 - 1175 F, or 1150 +/- 25 F.
      By direct conversion, 1125 - 1175 F = 607.2 – 635 C, which is 621 +/- 14 C. Not 620 +/- 14 C. NACE MR0103 has it right, NACE MR0175-3 is off by 1 degree.
      Note that in Table A.28 for UNS S45000, it has it correct as 621 C.
      Why does this one degree matter? When a heat treater reports age hardening temperature in Centigrade as 635 C, in Centigrade it meets MR0103, but not MR0175 and therefore it is not acceptable for NACE MR0175 service. When converted to Fahrenheit it meets both.
      Additionally, in Table A.29 for USN S15700, c) has 560 C = 1150 F. But 560 C = 1040 F. 565 C = 1150 F. That too should be corrected to 565 C to match ASTM A564 Table 4, and I note that there is no tolerance, or min./max. stated in this table, but maybe that is OK.
      What steps need to be taken to initiate this change?
      Background: There are inconsistencies and errors in the specified age hardening temperatures and ranges for precipitation hardening stainless steels.
      1. For UNS 17400 and UNS 15500, NACE MR0175-3 Tables A.27 (S17400 only), A.28 and A.30 specify age hardening temperatures as (620 + 14) °C [(1150 +- 25) °F]
      Note that 620 °C = 1148 °F; 621 °C = 1150 °F
      For comparison, NACE MR0103 (clause 13.9.2.3 & 4) specifies age hardening for these same materials as 621 °C + 14 °C (1 150 °F ± 25 °F)
      2. For UNS S45000, NACE MR0175-3 Table A.27 specifies (620 + 8) °C [(1150 + 15) °F].
      For UNS S45000, NACE MR0175-3 Table A.28 specifies (621 + 8) °C [(1150 + 14) °F].
      For UNS S15700, NACE MR0175-3 Table A.29 specifies 620 °C (1150 °F) (no range specified).
      For UNS S45000, NACE MR0175-3 Table A.30 specifies (620 + 8) °C [(1150 + 15) °F].
      For comparison, NACE MR0103 (clause 13.9.2.5) specifies age hardening for UNS S45000 as 621 °C (1 150 °F) (no range specified)
      For comparison, NACE MR0103 (clause 18.6.2) specifies age hardening for UNS S15700 as 621 °C (1 150 °F) (no range specified)
      Q1: Is it correctly understood that the occurrences in MR0175-3 of 620 °C in Table A.27, A.28, A.29 and A.30 are in error and those should be changed to 621 °C?
      A1:

      For BOTH UNS S17400 and UNS S45000, NACE MR0175-2002 has 620°C AND NACE MR0175-2003 has 621°C. In NACE MR0175/ISO 15156-2003, UNS S17400 has 620°C and UNS S45000 has 620°C in Tables A.27 and A.30 but 621°C in Table A.28. The 1150°F in the heat treatment of both these materials is a constant and the technical basis. This is a conversion issue. The conversion equation is T°C = (T°F -32) x 5/9. Using this equation, 1150°F becomes 621.1°C. 621°C is the correct conversion for these materials in Tables A.27, A28 and A30.
      The conversion issue for UNS S15700 and UNS S15500 respectively in Tables A.29 and A.30 is identical and the correct conversion from 1150°F is 621°C.

      Reference: MP Inquiry 2017-09

       

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    • 184. For CRAs, what is the maximum hardness of the weld consumable and the weldments?
       

      QUESTION:
      The statement I’m referring to is in NACE MR0175, Part 3, Sect A.2.3 Welding of austenitic stainless steels of this material group and the statement reads “the hardness of the weld metal shall not exceed the maximum hardness limit of the respective alloy used for the welding consumable.” It would be greatly appreciated if you could provide some clarification as to what the standard is referring to by the “maximum hardness limit of the respective alloy” and where I can find these values.

      Answer
      The maximum consumable hardness applies to the corresponding base metal (UNS number composition). This has been defined as the maximum hardness that is listed in NACE MR0175/ISO 15156 for that UNS number or meets one of defined alloy classes that is in the NACE MR0175/ISO 15156. The question that you ask does not have a defined answer if the consumable used does not correspond to an existing UNS or does not fit one of defined alloy classes that is in the NACE MR0175/ISO 15156 standard. For a better understanding of weld cracking resistance requirements and especially for this latter case, you are directed to ISO 15156-3, Clause 6.2.2 where the cracking resistance of weldments are addressed.

      Reference MP Inquiry 2017-10

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    • 185. In NACE MR0175, can I qualify a fillet with a but weld coupon?
       

      QUESTION:
      We have one WPS Qualified in butt joint and Hardness survey done according to NACE MR 0175 (7.3.3.3 Figure 2) on Butt weld coupon.
      Is it correct that we cannot use the above WPS in a fillet weld joint, because the fillet weld hardness survey is not carried out.

      Answer:

      The applicability of weld procedure qualification tests for specifications is in accordance with the welding codes. For fillet welds, a hardness survey shall be in accordance with NACE MR0175/ISO 15156-2, Clause 7.3.3.3, Fig. 3. The use of butt weld hardness tests to qualify a fillet welding application is not specifically addressed in NACE MR0175/ISO 15156-2. The requirement of NACE MR0175/ISO 15156-2 is that the hardness values in the weld and heat affected zones remain in compliance. You may need a consultant to assist you in this determination.

      Reference MP Inquiry 2017-11 (NACE MR0175 Part 2 7.3.3.3

      Do you need urgent welding support to comply with NACE MR0175? Talk to our team.

       

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    • 186. API 5CT proprietary grades and NACE MR0175
       

       

      Q1. NACE MR0175 Part 2 Table A.3 references “Proprietary Grades” for three temperature ranges. There is no definition of “proprietary grades” in NACE MR0175. However, this suggests that not all materials will be adequate despite meeting the Table A.3 mechanical / product form requirements. Is there an accepted definition of “proprietary grade”?
      Q2. Table A.3 is entitled “Environmental conditions for which grades of casing and tubing are acceptable”. A.2.2.3.1 refers to Table A.3 in the context of ISO 11960 and API 5CT grades. Other sections of A.2.2.3, not directly referencing table A.3, refer to tubular components as well as casing and tubing. Is Table A.3 restricted to Casing and Tubing?
      Q1. NACE MR0175 Part 2 Table A.3 references “Proprietary Grades” for three temperature ranges. There is no definition of “proprietary grades” in NACE MR0175. However, this suggests that not all materials will be adequate despite meeting the Table A.3 mechanical / product form requirements. Is there an accepted definition of “proprietary grade”?

      A1: Proprietary grade as a term does not have a definition in NACE MR0175/ISO 15156-2. NACE MR0175/ISO 15156-2 Table A.3 defines what constitutes the proprietary grades and specifically references clauses A.2.2.3.2 and A.2.2.3.3.

      Q2. Table A.3 is entitled “Environmental conditions for which grades of casing and tubing are acceptable”. A.2.2.3.1 refers to Table A.3 in the context of ISO 11960 and API 5CT grades. Other sections of A.2.2.3, not directly referencing table A.3, refer to tubular components as well as casing and tubing. Is Table A.3 restricted to Casing and Tubing?

      A2: NACE MR0175/ISO 15156-2 Table A.3 is restricted to tubular components including casing and tubing. Tubulars are noted in the column for temperatures less than 65°C (150°F) and well as the referenced clauses A.2.2.3.2 and A.2.2.3.3.

      Reference MP inquiry 2017-12 NACE MR0175 Part 2 A.3

      If you require assistance with the NACE MR0175 requirements for proprietary grades; or if you are considering the use o proprietary grades, talk to our team of oilfield metallurgist to discuss the material selection for your tubulars.

       

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    • 187. What is the minimum temperature for PWHT of carbon steels according to NACE MR0175?
       

       

      Question: According to NACE MR0175, what is the minimum post weld heat treatment temperature (PWHT) for carbon and low alloy steels?

      Answer: ANSI / NACE MR0175 / ISO 15156 – 2 in clause A.2.1.4 states that a minimum temperature of 620°C (1150°F) is required for low alloy steels. There is no minimum temperature requirement for carbon steels.

      Question: Is PWHT mandatory as per NACE MR0175?

      Answer: ANSI / NACE MR0175 / ISO 15156 – 2 in clause A.2.1.4 states that weldments that do not comply with the standard requirements (hardness) shall undergo PWHT.

      Our team of welding engineers can help you define the project requirements to comply with NACE MR0175. Talk to our team today!

       

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      Regarding new revision of NACE MR0175/ ISO15156-2 (2015) Section A.2.1.4, I have following question:
      - On 2009 revision: minimum post weld heat treatment temperature (PWHT) shall be 1150 F for Carbon and Low Alloy Steel. With the changes on 2015 “ A minimum PWHT at 1150F shall be used for low alloy steel”, is minimum PWHT temperature at 1150 F apply to Carbon Manganese steel as well or this temperature is just applicable to Low Alloy steel.?
      - If minimum PWHT temperature at 1150 F is not applicable to Carbon Manganese steel, is there any minimum PWHT temperature requirement applicable to carbon manganese steel?
      (MP INQUIRY #2017-13)
      ANSWER:
      Q1: Regarding NACE MR0175/ ISO15156-2 (2015) Section A.2.1.4, the 2009 revision states that the minimum post weld heat treatment temperature (PWHT) shall be 1150 F for Carbon and Low Alloy Steel. The 2015 revision states “ A minimum PWHT at 1150F shall be used for low alloy steel”. Does the minimum PWHT temperature at 1150 F apply to Carbon Manganese steel as well or this temperature is just applicable to Low Alloy steel?
      40
      A1: The 1150F requirement is specific to low alloy steels. Note that carbon and carbon manganese steels still are required to comply with the hardness requirements as defined in Table A.1 when the SMYS exceeds 52 ksi. As noted in Clause A.2.1.4, as-welded carbon steels, carbon-manganese steels and low-alloy steels that comply with the hardness requirements of Table A.1 do not require post-weld heat treatment.
      Q2: If minimum PWHT temperature at 1150 F is not applicable to Carbon Manganese steel, is there a minimum PWHT temperature requirement?
      A2: There is no specific defined PWHT minimum temperature defined for carbon and carbon-manganese steels. The PWHT requirement is that it must yield a product that complies with the other requirements defined by NACE MR0175/ ISO15156-2 Clause A.2.1.4

      Reference MP Inquiry 2017-13 (NACE MR0175 Part 2 A.2.1.4)

       

       

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    • 188. In NACE MR0175, what are the hardness requirements for SS254Mo (UNS S31254)?
       

       

      We have a query about Hardness of SS-254SMO (Grade) S31254 (UNS Number). We used ASTM A182 Gr F44 in Valve Components (Seat ring and Bonnet Bush).
      As per Nace MR 0 175 Hardness doesn’t specify for the UNS S31254 material. But Nace MR 0 103 Stated that 35 HRC (Max).
      Please clarify the below.
      1. Nace MR 0 175 Hardness not specified for SS-254SMO (Grade) S31254 (UNS Number) – Correct or Not?
      78
      2. Referring Nace MR 0 103 specified for SS-254SMO (Grade) S31254 (UNS Number) – 35 HRC (Max) – Please confirm.
      The applicable tables for the subject alloy are A.8 thru A.11. As shown in Table A.8, there are no hardness requirements for material in solution-annealed condition used for any equipment or components; however, the cast version of UNS S31254, which is UNS J93254 (solution heat-treated and water-quenched condition), has a maximum hardness of 100 HRB. Table A.9 for downhole tubular components and packers and other subsurface equipment indicates that the material shall be in the solution-annealed and cold-worked condition with a maximum hardness of 35 HRC.

      Reference MP Inquiry 2017-18 (NACE MR0175 Part 3 A.3.2 Table A.8)

       

       

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    • 189. NACE MR0175 and API 938-C have different limits for superduplex stainless steels. Why?
       

      Please be informed that as per NACE MR0175/ ISO 15156, Super duplex stainless steel material can be used for temperature Up to 232 deg. C and partial pressure of H2s 3 Psi maximum with any combination of chloride concentration and in situ pH occurring in production environment is acceptable. However, based on API 938-C, the experimental data of critical pitting and crevice critical temperature of super duplex stainless steel material (Grade 2507) indicates that the maximum temperature it can be used as 80 deg. C and 50 deg. C respectively. Hence, would like to solicit the clarification on discrepancy in temperature limit for using of super duplex stainless material.
      Revised Question: Regarding NACE MR0175/ISO 15156-3 Tables A.24 and A.25, super duplex alloys are listed for service up to 232C and 3 psi H2S with no limits on chloride and in-situ pH, the attached section of API 938-C shows lower maximum temperatures (80C and 50C respectively for pitting and crevice corrosion). Please explain the discrepancy.

      Answer: NACE MR0175/ISO 15156-3 is a document that addresses environmental cracking in the presence of H2S; the standard title defines “Materials for use in H2S containing environment in oil and gas production”. The standard does not currently address pitting and crevice corrosion. The current values that are in the document are based on successful ballots and history. Note that the tables state “production environments” which are oxygen-free. The subject of API Technical Report 938-C is “Use of Duplex Stainless Steels in the Oil Refining Industry. You may need to employ a consultant to assist you with your particular application.

      Reference MP Inquiry 2017-17

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    • 190. In NACE MR0103, is carbon steel allowed "hot-forged" or is heat treatment mandatory?
       

      Question:
      NACE MR0103 in section 13.1.1 allows "hot rolled" as a heat treatment condition for carbon steels. Is this applicable for flanges, fittings, seamless pipe, etc which are not produced by rolling? Hot rolled can be interpreted as “hot formed” for product types other than plate? ANSI / NACE MR0175 / ISO 15156-2 in paragraph A.2.1.3 provides an allowance, and there is documented evidence that “hot formed” ASTM A105 and A234 WPB and WPC flanges and fittings are fit for purpose.

      Answer:
      Hot-rolling and hot-forming are not equivalent. Forged material shall be heat treated to the requirements of 13.1.1

      Reference NACE MR0103/ISO 17945 clause 13.1.1

      Our team of metallurgists and corrosion experts is here to help you with the interpretation and implementation of ANSI / NACE MR0103 / ISO 17945.

       

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    • 191. According to NACE MR0103, What is a “nace material” and who is responsible to make sure it really is a “nace material”?
       

      According to NACE MR0103 / ISO 17945, What is a “nace material” and who is responsible to make sure it really is a “nace material”?

      Q1: Who should be the entity that guarantees the conformance of NACE MR0103 / ISO 17945? Raw material supplier (e.g. mill or stockist) or fabricator?

      Q2: What do you think of the idiom “NACE material”? Is it an official expression?

      Many of fabricators are applying “NACE material” to fabricate pressure vessels or pipings when wet H2S Service is specified. And “they” say that the conformity of NACE MR0103 should be guaranteed by mill and specified on mill certification. One mill says that they put “NACE MR0103” in mill certification when purchaser requests but there is no difference with other normal CS order since the base metal hardness and chemistry specified in the standards are within the range of their ordinary CS products. However, I am wondering this kind of authentication since as far as I know, NACE MR0103 / ISO 17945 requires not only base metal hardness and chemistry but the weldment control as a primary factor to prevent SSC

      A1: Responsibility is defined in section 5 of MR0103/ISO 17945. Per 5.2, the manufacturer is responsible for meeting the metallurgical requirements of the standard. Beyond that, MR0103/ISO 17945 provides no guidance.

      A2: MR0103/ISO 17945 provides no guidance on how compliance shall be documented. It is up to the manufacturer and end user to determine what documentation is adequate to establish compliance with the requirements of the standard

      Reference: NACE MR0103 Inquiry

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      • 192. What are the hardness requirements for cobalt alloys as per NACE MR0175?
         

        Question 1:
        The main obstacle we foresee is that in Section A.10 Table A.39, Environmental limits for cobalt-based alloys used as springs, we see that the requirements for UNS R30003 are:
        -Shall be cold worked
        -[Shall be] age-hardened
        -[Shall be] maximum 60 HRC
        -This requirement means, in our interpretation, that after the cold working, and age hardening, we must be able to prove that the HRC hardness of the end product falls at or below 60HRC.
        -This presents a problem – due to the geometric constraints of spring design, the area presented for hardness examination can be both very narrow and thin. This drives testing to either Knoop or micro-Vickers hardness. This means we are relying on a conversion, like ASTM E140 Table 3, to approximate hardness. ASTM very clearly states that converted values are approximate, and may not be accurate. -ASTM E140 also lacks a conversion table that covers high nickel alloys in the range up to 60 HRC.

        Answer 1:
        Q1: Regarding 15156-3 Table A.39 for UNS R30003, we believe that the limitations for the alloy as springs are (1) shall be cold worked, (2) shall be in the age-hardened condition and (3) shall have a maximum hardness of 60 HRC.
        A1: Your interpretation is correct.

        Question 2:
        In what way is conformance to NACE MR0175:3 Table A.39 able to be assessed, for springs of small cross section which cannot be tested with the standard 150kgf HRC hardness test?

        Answer 2:
        Q2: How do we prove compliance to the 60 HRC limit when (1) the geometry prevents use of HRC and (2) suitable hardness measurements such as Vickers (DPH) or Knoop can be used but there are no published conversion Tables such as ASTM E140 that apply to this alloy/hardness range?
        A2: This is outside the scope of NACE MR0175/ISO 15156 but there is no prohibition from you developing hardness conversions based on test data.

        Question 3:
        Additionally, can the material also be considered compliant without age-hardening?
        Are there corrosion issues related to non-age hardened cobalt alloys?

        Answer 3:
        Q3: Additionally, can UNS R30003 also be acceptable in the cold worked condition without age-hardening? Additionally, are there any corrosion issues with the nonage hardened cobalt base alloys?
        A3: There was a recent successful ballot to NACE MR0175/ISO 15156-3 Table A.40 that once published will permit the use of the UNS R30003 in both the cold worked and the cold worked + aging conditions. However, Table A.39 does not include the as cold worked condition without subsequent age hardening. The inclusion of this ascold worked condition to Table A.39 would require a successful ballot to NACE MR0175/ISO 15156.

        This question is in relation to NACE MR0175/ISO 15156-3 Table A.39
        Reference MP inquiry #2017-07

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      • 193. In NACE MR0175, What does"shall exhibit a threshold stress >=95% of the actual yield strength (AYS)" mean for UNS S41500?
         

        NACE MR0175 / ISO 15156 in part 3, clause A.6, table A.22 requires impellers manufactured with martensitic stainless steel UNS S41500 to exhibit a threshold stress ≥95 % of actual yield strength in the anticipated service environment, this may involve testing as per NACE TM0177 2016.
        We have helped clients to qualify UNS S41500 for sour service use.
        Question 1:
        In accordance with Table A.22 of NACE MR 0175 / ISO 15156-3 “Environmental and materials limits for martensitic stainless steels used as compressor components for compressor impellers in H2S-containing environments, S41500 steel is recommended. Please clarify the requirements of Notes "c" of Table 22, namely:
        - in laboratory SSC tests, shall exhibit a threshold stress =95% of the actual yield strength (AYS);
        - if the design stresses for the product are less than the actual yield strength (AYS) by a factor of 1.5, what stress level are allowed to be used in laboratory tests for SSC.
        Answer 1:
        Q: Regarding 15156-3 Table A.22 for UNS S41500, footnote “c” states if used for impellers, the alloy shall exhibit a threshold stress = 95% of actual yield strength in the anticipated service environment. If the design stresses are less than the actual yield strength by a factor of 1.5, what stress level is allowed in laboratory tests to demonstrate compliance?
        A: Table A.22 requires the 95% threshold stress of the actual yield strength with no provision for lower acceptable stress levels; product/component design stresses are generally not covered by NACE MR0175/ISO 15156.
        This question is in relation to NACE MR0175/ISO 15156-3/A.6.2
        Reference MP inquiry #2017-08

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      • 194. What happens when HIC, SOHIC or SZC fails in testing as per NACE MR0175 Part 2 Clause B.4?
         

        Question 1:
        Application of section B4 (Test procedures to evaluate the resistance of carbon and low-alloy steels to SOHIC and SZC). Our Interpretation: Section B4 applies to SOHIC/SZC only. Where SSC is required section B3 applies.
        Answer 1:
        Section B.4 applies only to the evaluation of resistance to SOHIC and SZC as indicated, but per B.4.1 the "materials shall have been qualified with respect to SSC resistance for the design conditions prior to the SOHIC/SZC evaluation." which is B.1 - B.3

        Question 2:
        Clause B.4.2.3 (Evaluation and acceptance criteria for FPB test specimens) third paragraph : Sections produced in these ways shall be examined for possible ladder-like HIC features and other cracks related to SOHIC or to soft zones of a weld (SZC). No ladder-like HIC features nor cracks exceeding a length of 0.5 mm in the length of 0.5mm in the through thickness direction are allowed”. Our Interpretation : the word “nor cracks’ refers to cracks associated to SOHIC and SZC only. Other than ladder-like, SOHIC and SZC including single HIC (no ladderlike) types of cracks exceeding in length the 0.5mm are accepted.

        Answer 2:
        Part of the referenced text is incorrect as noted above. The missing component in your interpretation is the last part of the paragraph "No ladder-like HIC features nor cracks exceeding a length of 0,5 mm in the through thickness direction are allowed." Thus, the paragraph does not infer what you indicate is your interpretation.

        This question is in relation to NACE MR0175/ISO 15156-2/B.4.2.3
        Reference MP inquiry #2017-20

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      • 195. What is the NACE MR0175 criteria for retesting HIC?
         

        Question 1:
        We have a question on interpretation of clause B.2.2.2 e) in annex B of MR0175 / ISO 15156-2:2015. Third paragraph says: Re-testing is permitted as follows. If a single specimen fails to satisfy the acceptance criteria, … two further specimens may be tested. If after HIC testing a 0.5” plate to TM0284, two specimens out of three fail to satisfy the acceptance criteria, is it permitted to test four further specimen in order to qualify the batch?

        Answer 1:
        MR0175 / ISO 15156-2:2015 – Annex B, Clause B.2.2 Qualification of manufactured products; this clause allows for re-testing in the event of one of the required triplicate specimens (per test batch) failing to satisfy the acceptance criteria. In addition, the clause also states that the cause of the failed performance shall be investigated. If in fact the material is found to conform to the manufacturing specification, then two further specimens may be tested. However, it is not implied that multiple specimens may be subject to re-testing for a given batch. The particular paragraph closes with the statement that further retests shall require the purchaser’s agreement.
        This question is in relation to NACE MR0175/ISO 15156-2/B.2.2.2
        Reference MP inquiry #2017-21

        The team at Oil and Gas Corrosion Ltd has prepared checklists that will help you make sure your material complies with NACE MR0175, visit the live and fully functional checklist for:

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      • 196. What are the NACE MR0175 stress relief requirements for fibre deformation greater than 5%?
         

        Question: NACE MR0175 part 2 Annex A section A.2.1.2 refers to fibre deformation greater than 5%. Is this referring to surface strain when a residual tension stress is applied as a result of manufacturing processes? A.2.1.6 Cold deformation and thermal stress relief Carbon and low-alloy steels shall be thermally stress-relieved following any cold deforming by rolling, cold forging or other manufacturing process that results in a permanent outer fibre deformation greater than 5 %. Thermal stress relief shall be performed in accordance with an appropriate code or standard. The minimum stress relief temperature shall be 595 °C (1 100 °F). The final maximum hardness shall be 22 HRC except for pipe fittings made from ASTM A234 grade WPB or WPC, for which the final hardness shall not exceed 197 HBW.

        Answer: YES

        This question is in relation to NACE MR0175/ISO 15156-2/A.2.1.2
        Reference MP inquiry #2017-22

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      • 197. In NACE MR0175, What is a carbon-manganese steel?
         

        Question:
        ISO 15156-2 Annex A.2.1.4 differentiate between “carbon steel”, “carbon manganese steel” and “low-alloy steel”. The terms “carbon steel” and “low-alloy steel” are defined in ISO 15156-1, but not “carbon manganese steel”. What is the definition of “carbon manganese steel” in the scope of NACE MR0175?
        Answer:
        Although not directly defined in ISO 15156-1, the definition of carbon manganese steel is inferred in the definition of carbon steel. As described, these alloys may contain up to 1.65 mass percent Mn. The MP will discuss the need to provide a separate definition or enhance the definition in ISO 15156-1. However, a technical ballot would need to be submitted to make any suggested changes.
        This question is in relation to NACE MR0175/ISO 15156-2/A.2.1.4
        Reference MP inquiry #2017-23

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      • 198. For duplex and superduplex stainless steels, what is the NACE MR0175 maximum hardness for HAZ (heat affected zone)?
         

        Question 1:
        This request is related to ISO 15156 / NACE MR0175 part 3, A.7.3 Welding of duplex stainless steels. “The hardness of the HAZ after welding shall not exceed the maximum hardness allowed for the base metal, and the hardness of the weld metal shall not exceed the maximum hardness limit of the respective alloy used for the welding consumable.”
        Q1: In Table A.24 there are is no hardness limit for solution-annealed and liquid quenched or rapidly cooled duplex stainless steels. Does this mean that there is no defined hardness limit for the HAZ to be used for qualification of the welds?

        Answer 1:
        It is correct that in Table A.24 there is no hardness limit for solution-annealed and liquid-quenched or rapidly cooled duplex stainless steels. Hence, there is no requirements for welds in NACE MR0175 / ISO 15156. It should be noted that NACE MR0175 / ISO 15156 does not list hardness limits for other causes than cracking mechanisms defined in the document. For other properties the team at Oil and Gas Corrosion Ltd can help you define the requirements.

        Question 2:
        Or, do the hardness limits given in relevant ASTM standards apply? E.g. ASTM A790/A928/A240.

        Answer 2:
        Advice regarding which other standard(s) that may apply for a particular product is not covered by NACE MR0175 / ISO 15156.

        This question is in relation to NACE MR0175/ISO 15156-3/A.7.3

        Reference MP inquiry #2018-01

        The team at Oil and Gas Corrosion Ltd can help you resolve your queries qualification of duplex and super duplex stainless steel and their welding qualification to meet NACE MR0175 requirements. We can also help you comply with other standards such as DNV RP F112.
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      • 199. 4130, 4140 and low alloys. When does NACE MR0175 require SSC testing for qualification?
         

        NACE MR0175/ISO 15156 in part 2 / Annex A does quote 4130 grades A.2.2.3.2 Tubulars and tubular components made of Cr-Mo low-alloy steels (UNS G41XX0, formerly AISI 41XX, and modifications), if quenched and tempered in the tubular form, are acceptable if their hardness does not exceed 30 HRC and they have SMYS grades of 690 MPa (100 ksi), 720 MPa (105 ksi), and 760 MPa (110 ksi). The maximum yield strength for each grade shall be no more than 103 MPa (15ksi) higher than the SMYS. SSC resistance shall be demonstrated by testing each test batch and shall comply with B.1 using the UT test. A.2.2.3.3 Tubulars and tubular components made of Cr-Mo low-alloy steels (UNS G41XX0, formerly AISI 41XX and modifications), if quenched and tempered in the tubular form, are acceptable if the hardness does not exceed 26 HRC. These products should be qualified by SSC testing in accordance with B.1 using the UT test.

        Q1: Shall we consider that §A.2.2.3.2 applies only for hardness 26 < hardness = 30HRC and §A.2.2.3.2 applies only for hardness 22 < hardness = 26 HRC?

        A1: The requirements in A.2.2.3.2 go beyond just the specification of max hardness of 30 HRC as noted in the clause. Applicable limits for AYS are also indicated. SSC resistance in this case shall be demonstrated by testing as indicated in the clause.

        Q2: A.2.2.3.2 doesn’t quote ‘’test batch’’: Shall we consider that SSC results are considered as valid for any similar applications?

        A2: A.2.2.3.3 doesn’t quote ‘’test batch’’ and uses only ‘’should’’ : Are SSC results valid for any similar applications if tested once for material meeting A.2.2.3.3 requirements?
        If requirements are met in accordance to the stricter criteria applicable to materials of higher hardness (and additional yield strength requirements) than the ones applied in A.2.2.3.3, then those materials will also be considered acceptable for the lesser material condition (i.e. lower hardness). As noted in the clause, the word should implies a recommendation rather than a strict requirement as long as the rest of the requirements in Clause A.2 (and all-inclusive sub-clauses as applicable) are satisfied.

        Q3: Are any grade UNS G41XX with hardness = 22 HRC if Q&T in the tubular form, acceptable without additional testing as soon long as it meet NACE MR0175 chemical composition requirements (mainly S = 0.025 %....) ?

        A3: As noted in Clause A.2.1.1 (second paragraph) “Carbon and low-alloy steels, products and components that comply with A.2 are, with stated exceptions, qualified in accordance with this part of ISO 15156 without further SSC testing. Nevertheless, any SSC testing that forms part of a materials manufacturing specification shall be carried out successfully and the results reported. “Therefore, tubular materials with hardness <= 22 HRC that meet general and specific requirements in Clause A.2 (and all-inclusive sub-clauses as applicable) are acceptable without further testing. Please also note that chemical composition is not the only requirement that needs to be met. As noted in Clause A.2.1.1 – third paragraph, “The majority of steels that comply with the general requirements of A.2 are not individually listed; however, for convenience, some examples of such steels are listed in Table A.2, Table A.3 and Table A.4.” Also, NACE MR0175-2 = ISO 15156-2 ed 2015 7.2.1.4 SSC regions 1, 2 and 3. Documented field experience may also be used as the basis for material selection for a specific sour-service application; see ANSI/NACE MR0175/ISO 15156-1.

        Q4: Is there an official & recognized list associated to NACE MR0175-2 = ISO 15156- 2 ed 2015 for material qualified upon field experience?

        A4: There is no official record that tracked and documented field experience.

         

        This question is in relation to NACE MR0175/ISO 15156-2/A.2.2.3

        Reference MP inquiry #2018-02

        The team at Oil and Gas Corrosion Ltd can help you select low alloy steels 41XX for sour service and specify the correct requirements to assure fitness for purpose.

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      • 200. In NACE MR0175 Part 3 Clause A.3 are 3B materials qualified for all conditions?
         

        Question 1:
        Shouldn’t it have the same material restrictions of all type 3b materials, and be able to be used under the conditions stated in both entries for materials type 3b, and not only according to the first entrance? Otherwise, could you kindly explain the reason of this difference in limits, with such a similar chemical composition?
        Answer 1:
        Materials requirements for sour service are not solely based on chemical composition as there are other metallurgical conditions that directly impact their resistance and, thus, their specific sour service limits. Cast vs. wrought materials is an example of such differences in terms of metallurgical conditions that affect their resistance and as such need to be qualified accordingly. A ballot with the required testing data in compliance with NACE MR0175/ISO 15156-1 and NACE MR0175/ISO 15156-3, Appendix B or field experience data as described in NACE MR0175/ISO 15156-1 would be needed to extend current limits.
        This question is in relation to NACE MR0175/ISO 15156-3/A.3.2
        Reference MP inquiry #2018-03

        The team at Oil and Gas Corrosion Ltd can help you define the limits for highly alloyed austenitic stainless steels.
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      • 201. Does NACE MR0175 require impact test?
         

        NACE MR0175 is an international standard that provides the requirements for metallic materials exposed to H2S in oil and gas production environments. NACE MR0175 is identical to ISO 15156. ANSI / NACE MR0175 / ISO 15156 lists the requirements for carbon steels, low alloys and corrosion resistant alloy exposed to H2S in oil and gas exploration and production environments.

        There are no toughness test (impact or charpy v notch) requirements for materials compliance in NACE MR0175.

        If you require any further technical support contact us today!

         

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      • 202. What is NACE MR0175 compliance?
         

         

        What is NACE MR0175 compliance?

        Compliance with NACE MR0175 is achieved when all materials, fabrication and equipment comply with the requirements of ANSI / NACE MR0175 / ISO 15156.
        NACE MR0175 is an international standard that provides the requirements for metallic materials exposed to H2S in oil and gas production environments.
        NACE MR0175 is identical to ISO 15156. ANSI / NACE MR0175 / ISO 15156 lists the requirements for carbon steels, low alloys and corrosion resistant alloy exposed to H2S in oil and gas exploration and production environments.
        NACE MR0175 also provides the environment limits i.e, amount of H2S expressed as partial pressure, the maximum chloride content, pH range etc. Equipment that complies with NACE MR0175 can only be used within the limits established by NACE MR0175.

        Our team can help you achieve NACE MR0175 compliance.

         

        With a wealth of experience in the oil and gas industry, we provide independent materials and corrosion consultancy to help companies reduce risk, save money and apply best practice in their oil and gas businesses.

        Find out more by getting in touch – you’ll get an answer from a qualified, experienced materials engineer every time.

         

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      • 203. Are carbon-manganese steels included in NACE MR0175?
         

        QUESTION:

        ISO 15156-2 Annex A.2.1.4 differentiate between “carbon steel”, “carbon manganese steel” and “low-alloy steel”.
        The terms “carbon steel” and “low-alloy steel” are defined in ISO 15156-1, but not “carbon manganese steel”.
        What is the definition of “carbon manganese steel” in the scope of NACE MR0175? (MP INQUIRY #2017-23)
        ANSWER:
        Although not directly defined in ISO 15156-1, the definition of carbon manganese steel is inferred in the definition of carbon steel. As described, these alloys may contain up to 1.65 mass percent Mn. The MP will discuss the need to provide a separate definition or enhance the definition in ISO 15156-1. However, a technical ballot would need to be submitted to make any suggested changes.

        NACE MR0175 is an international standard that provides the requirements for metallic materials exposed to H2S in oil and gas production environments.
        NACE MR0175 is identical to ISO 15156. ANSI / NACE MR0175 / ISO 15156 lists the requirements for carbon steels, low alloys and corrosion resistant alloy exposed to H2S in oil and gas exploration and production environments.

        this question is in relation to NACE MR0175 / ISO 15156 Part 2 Clause A.2.1.4

        Reference MP #2017-23

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