So what is it about words like approximate or recommended that make people commonly jump to a mandatory shall?????
I promise to vote negative on any B31.3 ballot that takes the word approximate out of the gap requirement. There is no need to make more out of this requirement than what is stated.
As for 3/32" its approximately close to 1/16"!
Instead of worrying about the gap, what about the filler metal, or undercuts at the toe of the welds, or leg height and geometry?
XHPIPE;
Being involved with Codes and Standards committees I agree, and a star for your negative vote along with mine for B31.1! Leave the wording as is.
metengr/XHPIPE
Had I a vote, I would vote negative with you. There is no reason to change the decades long wording. Unfortunately, a number of Owner/Engineers do not appreciate the present wording and the reasons for it and have required RT of socket welds to demonstrate conformance.
Please save me some time and tell me the numbers for the existing interpretations having to do with the socket weld gap. I am now very curious and I would like to educate myself on the full committees' reading.
I understand the current Codes wording RECOMMENDS an APPROXIMATE gap of 1/16 inch BEFORE WELDING (that is plainly written). There is nothing in either Code that requires any "after welded" gap. No need for further discussion there.
OK, summing it up. The answer to the original question by klkweld is simply "B31.1 and B31.3 RECOMMEND an APPROXIMATE gap of 1/16 inch. Please refer to B31.1 Figure 127.4.4(B) and to B31.3 Figure 328.5.2C".
Contrary to what I THOUGHT I was reading, I can now see that nobody in this thread objects to the APPROXIMATE gap of 1/16 inch BEFORE WELDING. I see that the point is that no matter what gap is used there can be no guarantee as to what the resulting after weld gap will be. Since the subject has generated previous inquiries and interpretations there is likely no need to go there again. No words to change, no negative votes required.
I find the experience of Welder4956... "If we set the gap at 1/16", the weld shrinkage would always close the gap to almost zero",... to be really interesting. It makes me wonder how many times, when the Gap-A-Let device has been used; it caused insufficient room for weld shrinkage. I also benefited from stanweld's experience regarding leakage when the pipe was inserted less than 1/4 inch. Since the range of NPS's for socket welds is all the way up to NPS 4, there is a need for experienced judgment in deciding the optimum pre-weld gap.
Why are you adding words to the code. The word "Recommended" does not exist in the code with regard to this subject. It is a minimum requirement of an approximate gap. So it is a requirement, not a recommendation, but the specified dimension of the gap is approximate.
The question raised in our forum is construction concern. So, based on ASME/ANSI B31.3, because i'm working with , it is clear that 1/16 inch is requiered. in general we have to ovoid any contact steel - steel .
since we are talking about socket weld, the branch connection is greater than 2 inchs , can you use tee in stead ?
Adding a little information:
The last project using socket welds that I was associated with was what in some circles could have been considered a nightmare.
The project had a total of 3268 welds of which 2013 were socket welds. These welds not only had to meet the applicable codes but were also required to meet our piping standards. Our standards called for a 1/16" gap after welding and minimum engagement of 2t (pipe) using 2 passes.
This was a turnkey project until the pressure testing phase started. The initial test was a vacuum test with a pressure decay of less than 1 # hr. They were unable to pull a vacuum on completed section. This attracted our group’s attention and a cursory visual inspection of the completed socket welds prompted a scope change on the project to where we would do the weld inspection and testing. Our normal inspection requirements for piping in this service (vaporized heating fluid at 700? F) was VT, 100% RT, followed with a He leak test at 100 psig had been waved based on assurances by the contractor of their expertise and QC that convinced project management to go with a 5% RT program to save money. Our initial over site was not what it should have been.
Here is our inspection summary:
Of the 2013 Socket Welds, mainly 1" or 1.5" CS the following defects were found:
101 welds that had no gap or excessive gap. The sockets were being used as a crutch. In fact some pipe didn’t make it to the fitting.
75 welds that had Cap problems taken out by VT.
52 just bad welds, mainly porosity.
21 weld with fusion problems.
The second half of this project with an almost equal number of welds (socket and grove) had less than a 1% weld defect rate of all welds.
We went to court over our inspection program and after 7 years,just recently we won.
Something good did come out of this in that several welders who worked on the project have told me they now know how to fit and weld out socket fittings now. The negative side is that some have told me on later jobs they were told to stab it and one pass it as it’s only a socket weld.
To me, that's just pipefitting that's sloppy at best, and incompetent at worst. The number of guys out there who cannot work end to centre or centre to centre on their fitting work is large & growing. Many cannot even do 45* offsets. And rolling offsets? Get ready for a lot of trail and error and a pile of scrap pipe.
