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?
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