PWHT Thickness issue

[mamoizkhan1967]

Dear Experts. We are using ASME Section I, for PWHT we see the relevant table PW 39. It makes PWHT mandatory beyond a thickness of 19 mm. Similarly we see that using ASME Section VIII, for PWHT we see the relevant table which is UCS 56. It makes PWHT mandatory beyond 38 mm. My material is P-1 Gr-2. For my Power Boiler can i use ASME Setion VIII PWHT requirements as they are less stringent. Why their is a mismatch in Section I & VIII w.r.t PWHT?. Kindly some one explain.

 

[metengr]

Prior to the 2013 Edition of ASME B&PV Code, Section I had a restrictive PWHT thickness, similar to B31.1 above 3/4 inch (19mm) thickness. This restriction was relaxed to allow for carbon equivalent and preheat to exempt PWHT to a thickness greater than 1.5 inch (38mm).

To answer your first question, no, you cannot cherry pick more favorable PWHT requirements between code book sections. Second, the relaxation of Section I PWHT was done to synch with Section VIII, Div 1 for consistency purposes related to carbon steel base materials. This also happened in B31.1.

 

[GenB]

My inspector would say... good try and shame on you for trying