PWHT of P1 Materials 1

[iam42]

Hey guys,

I have a job that has Trunnion welded to an 18" x 1.75" wall thickness 106C Pipe. The trunnion is 8" sch 80 (1/2" thick) and is attached with a 1/4" fillet.

I am hoping that this falls into the non-mandatory PWHT category of Table 132 (a).1. from B31.1 as the nominal thickness of the weld is 1/4" throat. I have attached a sketch showing the detail

Am I correct?

Thanks

 

[Duwe6]

1/4" fillet weld does not have a 1/4" throat. If the weld profile is perfect, the throat would be 0.707 x fillet leg length = 0.177" [3/16", sort of].
And yes, you are below the PWHT region, BUT ensure that the welder uses a good preheat even for the tacks. 100 - 150°F should be plenty, and will reduce the residual weld stress. Also, make the weld in 2 passes and do not allow much oversize. Too much throat = mandatory PWHT.

 

[iam42]

I'm now starting to question my own thoughts. After reading the code again. I do believe it does need PWHT due to one of the members being joined being 1.75" thick. This nominal material thickness does not fall into either paragraph Table 132 (a).1 or (a).2.

I would love to hear other peoples interpretation of this.

Tahnsk

 

[metengr]

Here is the definition of nominal thickness in B31.1;

132.4 Definition of Thickness Governing PWHT
132.4.1 The term nominal thickness as used in
Table 132 and Notes is the lesser thickness of (A) or (B)
as follows:
(A) the thickness of the weld
(B) the thicker of the materials being joined at the
weld

Self explanatory.

 

[iam42]

Thanks Metengr,

So my original thinking is correct?

 

[metengr]

Yes.