How critical are full penetration butt welds in joining two pipes for low pressure systems? 1

[Headphone5]

We had a vendor construct a small 2in piping system spec'd to ASME B31.3. MAWP is 200psig.

The pieces came back and didn't have full penetration welds for joining things like elbows and T-sections. Meaning they had a solid exterior weld but on the inside you couldn't see the weld, only the seam where the two pipe sections meet. This stood out to me but I'm not an expert by any means.

ASME B31.3 seems to require full penetration. But our vendor, whose expertise we trust and have a good relationship with, says it is pretty difficult to get full penetration on sch40 2". I kind of find this hard to believe. But since we're only at 200psig I'm wondering how necessary this is.

So I guess those are my 2 questions,
1. Is full penetration overkill for 200psig?
2. Is it pretty common to forgo full penetration when trying to meet ASME B31.3?

 

[FacEngrPE]

My experience is that rejecting non compliant welding sometimes gets you a new set of welders.
<story>Utility piping job 60 psi Natural Gas about 1985, my roll was owners engineer. I observed some butt welds that looked like they had too much undercut. I asked the forman if I could see the welders qualifications.
Next day all of the welds on the job were cut out, and different welders were on the jobsite. <end story>

Your supplier owes you good welds, Insist on it.

 

[StrucPatholgst]

Our welders helped construct the Pearl GTL complex in Qatar. 100% xray, full pen, 16 inch down to 1 inch. Getting full pen on small ID pipe is not rocket science. For a decent welder, it may take a coupon or two each day to dial in, but it is not difficult. From my experience, a full pen spec makes a decent welder snap to attention, and a so-so welder question his existence.

 

[r6155]

This is a classic situation due to the owner's lack of inspection.

Regards