Dave,
Personally, I would Dye Pen before stress relief, then stress relieve, then Dye Pen again after the part is cool enough. Depending on the grade of steel and the heat treat temperature, a lot can happen during the stress treatment.

Chuck

I look at it this way; your WPS is qualified with PWHT. You are not finished with the "process" until the PWHT is completed. Therefore, NDE is not allowed for final acceptance until after PWHT.

When we get into PWHT and RT, we always do an informational RT before the PWHT. We don't want to have to get into determination of whether an additional PWHT would be required if repairs are needed. If you find out about repairs before PWHT, the decision never has to be made.

All that aside, PWHT has the potential to cause indications that weren't present before. You have to be prepared to make repairs if NDE reveals rejectable indications.

Charles

In general, most of the welds we make that require PWHT also require RT because of the increased thickness needed for high pressure or temperature. We typically perform the code-required RT before PWHT, then perform a wet fluorescent MT after PWHT to verify no cracking has occurred. Occasionally cracking has occured in CrMo alloys due to high as-welded weld metal hardnesses that were not sufficiently reduced by PWHT and repairs were required. We would not normally choose PT after PWHT since the only alloys we weld that require PWHT are ferritic alloys and MT is much quicker and effective at detecting cracks with less surface prep required.