PWHT at 1250 instead of 1150 - P1 Group

[Geof]

Our heat treating contractor just sent a unit back. Reviewing the charts, we found that the unit was post weld heat treated at 1250°F instead of the specified 1150°F.

The item is a T-strainer - constructed of carbon steel body and flanges.

Will this cause any problems?

 

[metengr]

No. This temperature is below the lower critical transformation temperature for carbon steel.

 

[weldstan]

In general, I agree with metengr. Time at 1250 F and somewhat greater temperature may reduce tensile strength of some of the very low carbon medium manganese weld filler metals below their stated minimums. I have certainly seen it occur at 1275 F and 1300 F.