Boiler welded nozzle joint gap

[KevinBarr]

In B31.1, a 1/16" pre-weld gap is required in socket welded pipe joints between the pipe end and the shoulder of the fitting. thread178-25615 contains some discussion and even an explanation of the origin of this gap. However, I do not see any referral in the BPVC (sect. I or VIII) that addresses this gap or the residual stress said to remain if the two mating materials are bottomed out prior to welding (ref. Sect. I PW-16.1 figures and (z)). Is this "residual stress" addressed in another section of the BPVC or is this weld design not subject to these stresses?

 

[rhg]

Use butt weld instead of socket

 

[metengr]

The figures you reference in ASME B&PV Code, Section I Part PW specify a 1/16" recess (dashed line in each figure and (z) near the center of the weld prep).

 

[metengr]

Also forgot to mention that the welds depicted in these figures are considered partial penetration groove welds not socket welds.