PWHT for fillet weld under the scope of ASME B31.3

[Hollan Petersen]

Given that, in a 16 inches piping SA-106 Gr B, I need to weld lifting lugs made by plate SA-516 Gr 60 (throat thickness: 18 mm) and the thicknesses of welded parts are 40 mm for the lung and 12.7 mm for the pipe, I was reviewing the PWHT requirements of ASME B31.3 but I am a little bit confused if needs be for performing PWHT.

[wgadmin]

In accordance with ASME B31.3 par. 331.1.3(b), for a lifting lung, heat treatment is required when the thickness through the weld in any plane is more than twice the minimum material thickness requiring heat treatment. In your case the ''thickness through the weld in any plane'' is the leg length of the fillet weld and considering that the throat thickness is 18 mm then the leg length easily can be calculated to be 25.45 mm. Since the minimum wall thickness for requiring PWHT for materials with P-No 1 is 19 mm (table 331.1.1) it happens that you had to perform PWHT if the leg length was 38 mm. From all above it is made clear that there is no need for PWHT for your case.