pwht of lug

[maryam1979]

we are fabricating a pressure vessel with thickness of 20 milimeters.pressure vessel is Pnumber 8. the Pno:1 lug is welded to a Pno:1 pad and then pad is welded to pressure vessel.the weld nominal thickness of pad to lug is 20 milimeters. is it mandatory to perform pwht for the weld of lug to pad?

 

[metengr]

maryam1979;
Using ASME Section VIII, Div 1, UCS-56 requirements, if the weld nominal thickness between the lug and pad is 20mm, PWHT is not required provided you have used a 250 deg F preheat for welding.

 

[vesselfab]

the p8 pad to p8 shell weld is p8 and will not require PWHT

the p1 lug to p8 pad is out side of code limits and does not require pwht. Even if it was a code weld, you do not have to worry until over 1.25" (32 mm)and if you preheat per code rules you don't pwht untill after 1.5" (38mm)

in this case a warm preheat is suggested but is is no way required to be 250*

 

[metengr]

vesselfab;
The OP was the weld deposit between the lug and poison pad on the P8 vessel. Second, preheat at 250 deg F is recommended by me for this weld deposit thickness to avoid delayed cracking in the weld HAZ of the lug and poison pad material. You can do what you want.

 

[vesselfab]

weld that same joint almost every day.

weld the same way...warm

no problems