Using ASTM A 995 Grade 4A in H₂S-Containing Environments

This page includes two questions and answers pertaining to the use of ASTM A 995 Grade 4A (UNS J92205) 22 Cr duplex stainless steel in H₂S-containing environments, based on NACE MR0175/ISO 15156.

Question 1: Can ASTM A 995 Grade 4A be used in H₂S environments?

Answer 1: Yes, if the ASTM A 995 Grade 4A meets the material limits of Table A.24 of Annex A, it can be used in H₂S environments as long as the environmental limits given in Table A.24 are not exceeded.

Question 2: Does ASTM A 995 Grade 4A have to be listed in Annex D Table D7?

Answer 2: No, it is not necessary for ASTM A 995 Grade 4A to be listed in Annex D Table D7, which is believed to be for information purposes only and lists only some duplex stainless steels.

This page pertains to NACE MR0175/ISO 15156-3 Annex A and D. The reference cited for both questions and answers is ISO 15156 Maintenance Panel Inquiry #2006-04Q1 and #2006-04Q2.