B31.1 Butt Weld vs. B31.3 Groove Weld

[AgsMyDude]

I was attempting to compare visual examination acceptance criteria between B31.1 and B31.3 and am getting tripped up by the different terminology used by each code. B31.3 seems to favor the term groove weld in Table 341.2-1 while B31.1 uses butt weld in Table 136.4.1-1.

In my experience, large bore pipe and fittings are always specified with beveled ends which would (as I understand it) mean all butt welds are actually groove welds. Am I splitting hairs here or is there some distinction I'm missing?

 

[GBTorpenhow]

Yes, in a piping context a butt weld is always a groove weld.

Butt weld more generally describes the configuration of the joint with the two pieces butted up against each other as opposed to lap or tee, while groove weld describes the type of weld (vs fillet). So all butt welds in a piping context are groove welds, but not all groove welds are butt welds. B31.3 is referring to groove welds in general most likely, including for example the groove welds required for a full penetration branch connection weld shown in 328.5.4D, which are groove welds but not butt welds: