Acceptability of Austenitic and Duplex Stainless Steels in the As-Welded Condition in NACE MR0175/ISO 15156

Question:

In NACE MR0175/ISO 15156, is it acceptable to use austenitic and duplex stainless steels in the as-welded condition, or is post weld heat treatment (PWHT) required?

Answer:

When it comes to cast austenitic and duplex stainless steels, Part 3 of NACE MR0175/ISO 15156 does not specifically mention the requirement for post weld heat treatment. However, there is a statement stating that these alloys are only acceptable in the solution annealed and quenched condition. In my opinion, the as-welded condition does not meet the criteria of being solution annealed and quenched. So, can these alloys be utilized in the as-welded condition?

Answer:

Yes, these alloys can be used in the as-welded condition, as long as they satisfy the requirements outlined in Paragraph 6.2 of ISO 15156-3 and the corresponding Tables in Annex A. Specifically, Paragraph 6.2.2 states that welding procedure qualification records (PQRs) must include documented evidence of satisfactory cracking resistance.

This response pertains to NACE MR0175/ISO 15156-3, Clause 6.2.2.