Appendix C4 ASME Sec.I 2017 1

[ukmet]

Dear Gurus,

The newly added Appendix C4 in ASME Sec.I 2017 addresses the preheat and pwht requirements for P No.15E. It refers to table C-4-1 for soak band, heating band and GCB. I am confused regarding heating band and soak band. If I fulfill the minimum requirement of heat band requirements for soak band will already be fulfilled? Why it is separately mentioned?

Please guide

 

[pradipgoswami]

Please get a copy of AWS D-10.10-2008, the industry wide standard for Local Preheat and PWHT. Heating and Soaking band & GCB(Gradient Control Band) are well explained with diagrams. The essential need of the soak band & GCB is to reduce differential thermal stress on the metals being PWHT-ed. PWHT for P-91 in 740-760 Deg C will severe thermal stress. Hence those bands are needed to mitigate distortion & cracking arising from local PWHT.

Thanks

Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
ca.linkedin.com/pub/pradip-goswami/5/985/299