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

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We have a request for interpretation of item A. 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.


Paragraph A. 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. 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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