Min. Qualified Preheat Temperature
Min. Qualified Preheat Temperature
(OP)
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.





RE: Min. Qualified Preheat Temperature
131.4.2 P-No. 1. 175°F (80°C) for material which
has both a specified maximum carbon content in excess
of 0.30% and a thickness at the joint in excess of 1
in. (25.0 mm). Reheat may be based on the actual
carbon content as determined from a ladle or product
analysis in accordance with the material specification
in lieu of the maximum carbon content specified in
the material specification.
If you are oxyfuel or electrogas welding, this variable can be changed on the WPS without requalification but again, you must follow the requirements of the code of construction.
Gerald Austin
Iuka, Mississippi
http://www.weldinginspectionsvcs.com
RE: Min. Qualified Preheat Temperature
Thanks for your reply. But new PQR is necessary for reducing of 50 C from starting preheat temp. in PQR or from Max. temp. during welding in PQR?
RE: Min. Qualified Preheat Temperature
The "preheat" temp is always a "Minimum temperature before welding"
New PQR is necessary for reducing of 50 C from starting preheat temp. in PQR.
Gerald Austin
Iuka, Mississippi
http://www.weldinginspectionsvcs.com