NACE MR0175 Valve Materials for Sour Service

Per NACE MR0175/ISO 15156, carbon steel valve bodies (WCB, WCC) must not exceed 22 HRC (237 HBW) throughout the entire cross-section. This applies to the body, bonnet, and all pressure-containing parts. The material must be in the normalized, or normalized and tempered, condition. All weld repairs must be post-weld heat treated (PWHT) and hardness-tested to confirm compliance.

Yes, but with conditions. Austenitic stainless steels (SS304/CF8, SS316/CF8M) are acceptable in sour service per NACE MR0175 when solution-annealed and limited in cold work. Maximum hardness is 22 HRC. Duplex (2205/CD3MN) is also acceptable at up to 28 HRC with ferrite content controlled between 35-65%. Super duplex (2507/CE3MN) is permitted up to 32 HRC. Martensitic stainless steels are restricted — only specific grades like F6a Class 1 (max 22 HRC) are allowed.

Yes. Saudi Aramco requires NACE MR0175/ISO 15156 compliance for all valves in sour service environments, as mandated by SAES-L-008 (piping material specification) and SAES-L-133 (corrosion protection). Given that many of Saudi Aramco's gas fields contain significant H2S concentrations, NACE compliance is a standard procurement requirement for gate, globe, ball, butterfly, and check valves on most upstream and gas processing projects.