Bending Stainless Steel Pipes

Propane burner?

Another way: a hydraulic pipe/conduit bender.

Oxy Acetylene torch heating will be fastest and safest also. Other alternate is just weld a bead over the pipe and cool it to shrink. Another one is cut the pipe partially by grinding and make weld joint after matching the flange.

You may wish to consult with the pipe manufacturer, or other expert that I would not pretend to be in this, depending on the internal and extenal exposure (I do wonder a little bit however about the possibility of "sensitizing" the stainless steel, or making it more prone to corrosion, with the oxyacetylene torch heat and bending etc.??)

The best way to remove misalignment in piping is cut it and weld in aligned condition. As the flange was broken and you have to weld with new flange, why to bend the pipe to align?

1" stainless steel pipe can be cut with hacksaw. Clean and wipe/dry the inner pipe before hot work. Do surface preparation by grinding, align and TIG weld it.

Just a note: often in America, when we say a flange is broken, we mean it is taken apart (e.g., by removing the bolts)--not necessarily (or even usually) do we mean the flange has broken off its attached pipe.

Thanks for the information, we call decoupled in India. My suggestion still stands. The best way to rectify the problem is cut, align and weld.

What's the inside pressure???

Always check (after bending) what is the pipe's out-of-roundness...usualy shouldn't be more than 4%.

Be carefull not to lose mechanical properties due to over heating - sometimes it's better to use cold bending technics.

Operating pressure is 90 psig. The line is back in service and we are planning to correct the misalignment by cutting and welding at the next outage of the compressor. Thanks very much for all the comments.

First off, I presume you have to replace the broken flange. I also presume that the other end of the tube ends in a flange. If so, disconnect the whole length of tube and fill it with dry sand. Dry is the key, as it will not compact properly if damp. You need to plug the end of tubing with a blind flange and stand it on end to fill it. Tamp it on the floor, gently but repeatedly on the closed off end, to compact the sand, and when completely full, block off the damaged end. You can now bend the tubing over a wooden mandril to fit your bending requirements, with very little deformation of the tubing walls. You may have to slip a piece of larger diameter tubing over the end of the 1" s/s tubing (as an extension handle) for added leverage when bending, if the bend is required towards the end of your tubing. Empty out your 1" s/s tubing of sand and re-align for fit before welding on your new flange in place. I would imagine you will have to go through this procedure a couple of times before you hit it right. If as you say, "slightly bending it" is all that's needed, I doubt you will need any heat at all. Dry, compacted sand and enough leverage force over a simple wooden mandril should be all that's needed for a slight bend without deforming or collapsing the walls of the tubing.

I believe some of you have misunderstood the citation 'broken flange' in my question. What I meant by 'broken flange' was that the flange was opened to remove the spool to carry out a repair at the fixed end of the line at the lube oil tank. The removed 1" spool was in good condition. The term 'break flanges' is often used in our industry. My apology for the misleading statement.

I have a couple of field techs who would hit it with a rosebud and a squirt bottle. Water on one side of a hot pipe will draw it anywhere you want.

Depending on the service, the metallurgical changes could scare the heck out of me.

1. Old guys know all the tricks.

2. Stuff used to blow up allot more often than it does these days.

-A-