Process for cutting welded pipe/cross headers in half?

[aeroUB]

I am making headers for a ‘pressure vessel’ out of pipe and crosses. It will be 4” sch. 40 steel pipe with two (2) 4” butt weld crosses. I would like to have these cut in half after being welded up and be able to use BOTH halfs. It will need to have a small kerf as I can’t have much material lost during the process. Maybe around 1/8” max?

This would all be done as opposed to using just butt weld tees, cutting in half and then scrapping half the pipe and tee. This would also cut down on the number of welds (which will need to be x-rayed also).

My question is what processes of cutting would work for these headers? EDM, laser, plasma, saw, torch? I’m not real familiar with what’s available and just would like some input and what would be the most suitable for this application.

Thanks for any input

 

[MikeHalloran]

Laser cutting 12 gage stainless sheet typically leaves a kerf .007" to .010" wide. Under magnification, it looks like closely spaced tiny holes were drilled (actually, blasted) to separate the parts, and there is a very small HAZ, so the cut face needs to be ground just a little, but nothing like you need to clean up after a plasma cutter. [ The as- delivered surface _looks_ clean and weldable, but my welders reported that it 'welded funny', _after_ trashing my blanks. ]

The machinery is expensive, so a lot of it goes to companies that do nothing else and can keep it busy enough to pay off the investment. The process is very, very fast.

I'm not sure how many have been sold, but multi-axis laser cutters exist, capable of cutting fancy holes, bevels and conjugate keys in round and square tube. The Tube and Pipe Journal, house rag of tpa.org, would be a good place to start looking for them.




Mike Halloran
Pembroke Pines, FL, USA

 

[aeroUB]

I wont be looking to do this our selves, but will have some place do the cutting for us after we weld the headers up. I just want to know what processes would be the best most cost effective to use. The surface that is left by the process wont really be of concern as long as the kerf is small, because the edge will be beveled for later welding to a 'tubesheet'.

You refer to 12ga. but is this a resonable process for 4" Sch. 40 pipe and crosses? Also, there would be a good quant. of these, not just 1 or 2 of them. At least 70 and up to 150, just for now.

Thanks

 

[MikeHalloran]

You need a bigger laser to cut thicker material, which in turn limits the selection of cutting vendors. Just figure out the thickness and the material, and start calling around. Most of the vendor's variable cost has to do with getting the workpieces in and out of the machine, so your quantity will pay for a little fixturing.






Mike Halloran
Pembroke Pines, FL, USA

 

[dicksewerrat]

I'd look at a old fashioned power metal saw.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[DDRSS10]

You can get kerfs in the .06-.09 range with a band saw. any shop with a good saw can pound out these cuts with good precision. I would consider this about the only cost effective method.

Nick