ST 17-4 PH UNS S17400 Material for NACE Applications: Which Table Applies to Surface Safety Relief Valves?

This page provides guidance on the use of SST 17-4 PH UNS S17400 material for NACE applications, specifically for surface safety relief valves with internal components made of this material. The inquiry seeks clarification on which table from NACE MR0175/ISO 15156-3 applies to these valves.

According to the NACE MR0175/ISO 15156-3 standard, Tables A.27, A.28, and A.30 list SST 17-4 PH UNS S17400 material for NACE applications. However, only Table A.27 contains limitations for partial pressure H₂S and PH. The answer to this question depends on the intended service environment, and the equipment user is responsible for selecting appropriate materials in accordance with the standard.

This question relates to NACE MR0175/ISO 15156-3 A.8.2, Tables A.27, A.28, and A.30, and the reference cited is ISO 15156 Maintenance Panel Inquiry #2011-17.

It’s worth noting that there is an update from 2016 concerning NACE MR0175 2015 – Technical Circular 1, which has implications for 17-4 PH. If readers require additional information regarding 17-4 PH metallurgy, they can contact the team for support.