PWHT Requirements for P-No. 4 Material

[timmckee]

What governs PWHT requirements for P-No. 4 Materials? We are replacing flanges and a section of pipe on a 10" diameter steam line. The pipe is Sch 40 (0.365" wall) A335 P11 (P-No. 4 material). The piping is Non Boiler External Piping B31.1. However our weld procedure states that any pipe diameter above 4" requires PWHT and references Table UCS-56 (which requires PWHT for piping over 4" in diameter).

Would Table UCS-56 only apply if this was a nozzle on a Sec VIII vessel or does it supersede B31.1?

Thanks for the help.

 

[Mr168]

UCS-56 would not be invoked for B31.1 piping if it weren't for your WPS.

If you can revise the WPS to reflect Table 132 in B31.1, your 4" diameter requirement goes away. Assuming you meet all the requirements of Table 132 (which it sounds like you would), you would be exempt from PWHT.

 

[metengr]

What governs PWHT requirements for P-No. 4 Materials?

The code of construction most applicable to the work being performed or an engineering specification, if applicable.

 

[timmckee]

Thank you for the help.