[Poland308]

On some small diamiter pipe welding 3/4 of the way around or even all the way around for a single pass is not going to cause warping issues. An example of this would be welding half couplings onto pipe for test ports or taps. If it was tacked well and sitting tight to the pipe it has no where to pull to. If this were not the case and stoping durring the first pass was required to keep it from warping then the use of positioners to rotate a pipe continuously as it is welded with a mig machine would cause all sorts of problems. Yet fab shops everywhere successfully weld even large diamiter pipe where each pass is welded in a single weld from start to finish.

[DLewis0289]

Yep we do it all the time in. We do this thing on chilled water called a "hybrid" piping system. We pre-fab weld pipe in positioners (flanges, el's with flanges, etc.) and then put Victaulic grooves on the other end for bolt up on site. I think it's cheesy, but that is what they pay for. In the engineers mind it should be a seamless bolt up, just like a Lego set, zero on-site welding. When that happens I will make sure to report back.

[wheresmejumper]

I also weld pipe by day.some jobs you get by with being close.most of the work i do,close isnt close enough.
if youre welding a spool thats tacked in position you can worry a little less about distortion,as the structure holds itself holds some strength.if you are welding 2 flanges to a short pup then the tolerance is tight.a 2 inch flange is probably 6 inches diameter, 1/32 out over that 6 inches is a big deviation from true.the fitter better have a big hammer

[DLewis0289]

I couldn't agree more. I actually just finally received the utility patent early this year for a tool we designed that is perfect for the application you are talking about. We are currently working with a well known tool company (their tools are red) to finalize the manufacturing engineering and anticipating store shelves mid 2017. Attached is a couple of the prototype photographs in our patent documents. Our people have been field trialing it for 18 months and the fitters won't do without it. (Target retail price $22.00)

You could install those two flanges on the pup (stub) in less than 5 minutes, including tacks with laser two hole accuracy and both axis dead nuts square. Leaving your pipe stands and two hole pins in the truck.

TLL.jpg (24.44 KiB) Viewed 1113 times

Our first working prototype, been through hell and back during durability trials.

image1 (2).jpg (35.01 KiB) Viewed 1113 times

[wheresmejumper]

Great idea. Will have to try when theyre out

[AKweldshop]

Nice stuff