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In NACE MR0175, Are 17-4PH hangers considered “subsurface equipment”?

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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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