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?
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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