Sch 120 SA 333 Pipe max interpass temp required w/ PWHT

[bradsr0138]

I have 10" thru 16" Sch 120 SA 333 pipe in my work scope and my experience has been to keep the interpas temp lower than normal on theis material. Our current procedure for this type of material has a max of 300 deg. F for interpass temp. It seems to me that stress relieving the material at 1100 deg. F would defeat the purpose of keeping the temp down while welding.

I guess my question is can I forget about the max interpass temp if I am going to PWHT?

 

[SJones]

Cooling rate during weld deposition is a factor in the final weld microstructure developed. Stress relieving will not alter that microstructure. If the welds are subject to impact test restrictions, relinquishing control of the interpass temperature should not be contemplated. Notwithstanding that, you may find the welders, if manual welding, getting a little hot and bothered! For information, the maximum recommended interpass temperature in API RP 582 is 315 deg C.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[Welder4956]

The maximum interpass temperature is limited to 100 F above that measured during the welding procedure qualification and recorded on the PQR per supplementary essential variable QW-406.3 in ASME Section IX. That variable also says that the limit applies unless PWHT is performed above the upper transformation temperature (which is 1775 F if I remember correctly). So the answer to your question is no.