PWHT B31.1

[flight23]

When you read the requirements of PWHT of P-1 materials The nominal thickness is 3/4" or less PWHT is not required. If you have a STD 6" Buttweld olet going on a STD 16" pipe how do you determine if the olet needs to be PWHT due to thickness?

 

[metengr]

The thickness of the weld deposit and not the base metal determines the requirements for PWHT.

 

[CodeRef]

It is defined in B31.1.

Please read Paragraph 132.4 and note that the terms "nominal thickness" and "nominal material thickness" are defined there.

The "nominal thickness" in accordance with Para.
132.4.1 may be the weld thickness under some specified conditions but the "nominal material thickness" is always the material thickness.
See the following interpretations: (found here)

http://cstools.asme.org/csconnect/CommitteePages.cfm?Committee=N10020200&Action=11005

Interpretation: (B31.1) 25-24
Subject: B31.1, Table 132, Postweld Heat Treatment
DateIssued: June 22, 1994
File: B31-94-027

Interpretation: (B31.1) 26-2
Subject: B31.1, Table 132, Postweld Heat Treatment
DateIssued: April 20, 1995
File: B31-94-027

ConfirmHistory:
Interpretation: (B31.1) 31-2
Subject: B31.1, Para. 132.4.1(A) and Table 132, Postweld Heat Treatment
DateIssued: July 15, 1997
File: B31-96-062