Why Are Uns S31600 and S31603 Listed Separately in NACE MR0175/ISO 15156-3 Table A.2?

In clause A.2 of NACE MR0175/ISO 15156-3, materials that comply with certain requirements are listed. However, UNS S31600 and S31603 are listed separately from other austenitic stainless steels, even though they meet the same requirements. This raises the question of why they are treated differently.

Do S31600 and S31603 Have Different Environmental Limitations Compared to Other Austenitic Stainless Steels?

The ISO 15156 Maintenance Panel was asked about the environmental limitations of S31600 and S31603 compared to other austenitic stainless steels. Their response stated that clause A.2 materials permit less highly alloyed grades than S31600 and S31603. Therefore, the answer to the second question is yes; S31600 and S31603 do have different environmental limitations than other austenitic stainless steels.

This inquiry is in reference to ISO 15156 Maintenance Panel Inquiry #2013-06.

At OGC Energy, we offer support with NACE MR0175 and austenitic stainless steels. Contact us for any assistance in this regard.