PWHT Temp for 1.25 Cr - 0.5 Mo
PWHT Temp for 1.25 Cr - 0.5 Mo
(OP)
Dear all,
I have an Heat Exchanger made by 1.25 Cr - 0.5 Mo (SA 387). AS per ASME VIII PWHT for P4 min temp is 593 C. But Our project spec stated that PWHT temp min is 670 C. I also read from KOBE cataloque temp min PWHT is 670 C.
My question what make these different value ? Is there any problem if my min temp PWHT is 593 ? Is there any mettalurgical reason ?
I have an Heat Exchanger made by 1.25 Cr - 0.5 Mo (SA 387). AS per ASME VIII PWHT for P4 min temp is 593 C. But Our project spec stated that PWHT temp min is 670 C. I also read from KOBE cataloque temp min PWHT is 670 C.
My question what make these different value ? Is there any problem if my min temp PWHT is 593 ? Is there any mettalurgical reason ?





RE: PWHT Temp for 1.25 Cr - 0.5 Mo
Post weld heat treatment can also be specified as a normalize and temper. In this case, the welded component is heated (at higher temperature) above the lower critical transformation temperature to eliminate the weld heat affected zone.
The normalize and temper is commonly specified during seam welded pipe and vessel component fabrication. However, this type of post weld heat treatment is typically not performed in the field or when installing nozzles or attachments to finished pressure parts because of cost and potential distortion concerns. The normalize and temper post weld heat treatment provides for uniform mechanical properties across the weld and base metal.
RE: PWHT Temp for 1.25 Cr - 0.5 Mo
RE: PWHT Temp for 1.25 Cr - 0.5 Mo
The sub-critical PWHT minimum temperature differences will not result in a longer lasting weld joint OR will outperform one over the other.