Min. Qualified Preheat Temp

[SHG]

If in preparing of test coupon for PQR I have the min. preheat temp. as starting temp. of welding, about 80 C and during the progress of the welding the temperature of the coupon raised for example to 250 C. May I specify the Min. Preheat Temp. in WPS as 30 C because of the para. QW406.1 of ASME Sec. IX.

 

[metengr]

Yes. You can always elevate preheat without re-qualifying the welding procedure. However, Section IX limits the decrease in preheat to 50 deg C.