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. 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?


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. 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. and A.4

Reference: ISO 15156 Maintenance Panel Inquiry #2015-07

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