How to Prevent Warped Small Welded Pipe?

8/16/2019

I've heard from several installers that small diameter schedule 10 pipe (such as 1-1/4") will warp if there's more than two welded outlets made onto it.

Would any installer/contractors weigh in on how you best combat this problem?

I could see larger diameter (1-1/2" or more) schedule 10 as a possible solution, which also helps hydraulics. I could also see voluntarily going to schedule 40 as a possible solution. Cutting the pipe into shorter segments and adding couplings would also help, but I could see the cost adding up for the labor, couplings, and additional hangers.

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5 Comments

Brian Gerdwagen FPE

8/16/2019 10:09:19 am

When I was a designer for a contractor, this would come up when welding sprigs on branch lines. It seemed like every sprig went a different direction instead of straight up. We found that more couplings and less welds per piece worked out best. Unless you want to use outlet couplings or Fit/Sock-it Fittings for every other outlet.

On the clock

8/16/2019 11:02:07 am

My welders, when hand-welding, always torpedo-leveled each POL so at least they were similar. But never found a way to avoid the warped pipe on 1¼", so I'd also be interested to hear if anyone out there had a solution. With a minimal price difference between 1¼" and 1½", we just went with 1½". The alternative of more pieces, grooves, fittings hangers, all adds up to more material costs, shop time, and installation time that will multiply throughout the job. (It's tough competition out there, to make money a designer needs think like an estimator and fitter, and understand the material and installation labor implications of everything.) One less coupling size to deal with on site was a small plus. Also, maximum hanger spacing increases at 1½" so you might have fewer hangers.
Indirectly related, a common designer mistake in that they do not make reducing grooved couplings (like the Vic 750) in every size combination. And our rule of thumb was don't reduce if you are only saving the diameter on one last stick of pipe on a line.

Vinnie

8/16/2019 11:07:37 am

We rarely fab welded outlets on 1 1/4" and don't fab 1" outlets on 1 1/4" at all. The cost difference is minimal to get a better looking product with 15' hanger spacing as On the Clock mentioned.

Mike

8/16/2019 08:16:27 pm

I've successfully welded 1/2“ outlets on Sch 10 for SSU's with no problem. I it calced at 1" but supplier said that would definitely warp.

But I wouldn't weld any bigger outlet on it.

Stainless Steel Fabrication Auckland link

1/18/2021 10:40:01 am

Thanks to the author for sharing such a great post. The article was very well written and providing great info about how to prevent warped welded pipe . It can be really great for people like me who are looking for grabbing more knowledge about it.

How to Prevent Warped Small Welded Pipe?

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