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In NACE MR0175 Table A.22, are martensitic stainless steels “limitless”? Do they need qualifying?

Environmental and Materials Limits for Martensitic Stainless Steels Used as Compressor Components in NACE MR0175/ISO 15156-3, Table A.22

Introduction

This page provides clarification on an inquiry regarding the interpretation of the Remarks on the maximum partial pressure requirement for H₂S in NACE MR0175/ISO 15156-3, Table A.22. The question concerns the acceptability of any combination of temperature, partial pressure of H₂S, chloride concentration, and in situ pH occurring in production environments. As a centrifugal compressor manufacturer, the inquirer often builds compressors for process gases containing trace amounts of H₂S.

Answer

Conformance to the standard is required for any trace amount of H₂S. The martensitic stainless steels listed in Table A.22 can be used in any production environment as long as they meet the metallurgical requirements indicated in the lower part of the table. This includes a resistance in the anticipated service environment of at least 95% of the actual yield strength of the impeller material using Annex B for laboratory testing. The qualification requirements for ISO 15156 are listed in §8 of NACE MR0175/ISO 15156-1.

Conclusion

This question pertains to NACE MR0175/ISO 15156-3 A.6.2, Table A.22, and the reference cited is ISO 15156 Maintenance Panel Inquiry #2010-06. If you need assistance in selecting and qualifying material to Table A.22, please contact our team for support.

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