Post Weld Heat Treatment as a PQR Essential Variable

[dynopepticman]

I have noticed a difference among certain codes regarding welding procedure qualification and post weld heat treatment as an essential variable. Some codes, such as AWS D15.1 state that any "addition, deletion or change" to PWHT requires requaification of the procedure. Other codes such as AAR M-1002 state that a "change" in the postweld heat treatment requires requalification.

Am I reading too much into this or does the M-1002 allow addition or deletion without requalification ? To me addition and deletion are also a change, but somebody at AWS obviously went through the trouble of writing what they did in AWS D15.1, I assume for a reason. Or maybe not.

 

[Golflinks]

The "CHANGE" in Usual codes would mean addition and deletion of PWHT to a qualified procedure requires Re-Qualification of the procedure.

However, the statement in AWS D15.1 has gone further in my opinion in that it means any change in temperature to that qualified would require re-qualification. This is perhaps justified in that the PWHT temp should be at least 20-25 degrees Centigrade lower than the tempering temperature for the case of Q&T steels.

 

[sip125]

See ASME Section IX - Welding Procedure - Essential variables.