warping pipes, howto

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I need to bend a couple of 1" steel pipes for a project I'm working on (custom shock towers). How effective would controlled warping (heating at intervals along one side) using a standard OA torch be for ~60 degree bends? How critical is the tip size/cooling method? I know I should pony up for a real pipe bender, but the torch is sitting in my garage and the pipe bender aint.Thanks!-David
Reply:I would think accuracy would matter here.  Using OA would not achieve very much in the way of accuracy.  You could probably get a local shop to bend the pipes for you...or rent the tool from a rental place.Smithboy...if it ain't broke, you ain't tryin'.
Reply:It's possible and accurate but I have never had any success.You could also bend a piece of flat bar into the shape you want and tack it on to your work bench.  Clamp on end of the pipe to the flat bar and pull the other end against the flat bar while heating.  Always allow the steel to cool slowly or it will become brittle.
Reply:Point well taken...I suppose that in place of a bender you could use a jig to get some pretty accurate bends.  But those bends in the pictures are so far out of my league it's laughable.Smithboy...if it ain't broke, you ain't tryin'.
Reply:You can do what is called a wrinkle bend using a torch.  The idea is to limit each wrinkle to no more than 15 degrees.  That means four wrinkles to make your 60 derees.  If you are bending the pipe so that the included angle is 60 then that is a 120 degree change or 8 wrinkles.   The old Union Carbide gas welding textbook showed the procedure.  I have done it with 1.5 inch pipe but it can be done with large stuff like 6 inch if you know how.   To make one wrinkle you heat a pie shaped wedge on the pipe and then pull until the wall buckles and forms a wrinkle.  I make up a 15 degree sweep so that I can compare and not ruin the effect by pulling more than 15 degrees.  A sweep is a piece of wood, cardboard or sheet metal cut at teh angle to form a template.   The trick is to form a nice red wedge then give a steady pull.  You have to have the pipe clamped or tack welded to a stationary object.  Leave the pipe extra long so that you have leaverage.  On big pipe you rig a hand winch to apply the bending force.   If done correctly the profile will not flatten significantly. You will have the wrinkles on the inside of the bend but the inside section will remain open to allow fluid to pass through.
Reply:You can do what is called a wrinkle bend using a torch.  The idea is to limit each wrinkle to no more than 15 degrees.  That means four wrinkles to make your 60 derees.  If you are bending the pipe so that the included angle is 60 then that is a 120 degree change or 8 wrinkles.   The old Union Carbide gas welding textbook showed the procedure.  I have done it with 1.5 inch pipe but it can be done with large stuff like 6 inch if you know how.   To make one wrinkle you heat a pie shaped wedge on the pipe and then pull until the wall buckles and forms a wrinkle.  I make up a 15 degree sweep so that I can compare and not ruin the effect by pulling more than 15 degrees.  A sweep is a piece of wood, cardboard or sheet metal cut at teh angle to form a template.   The trick is to form a nice red wedge then give a steady pull.  You have to have the pipe clamped or tack welded to a stationary object.  Leave the pipe extra long so that you have leaverage.  On big pipe you rig a hand winch to apply the bending force.   If done correctly the profile will not flatten significantly. You will have the wrinkles on the inside of the bend but the inside section will remain open to allow fluid to pass through.
Reply:If anyone finds a contemporary picture of wrinkle bending I would be interested.  The one I saw years ago must have been take in the 1930's from the appearance of the workmen's clothing and the surrounding equipment.Last edited by lotechman; 02-07-2006 at 08:48 PM.
Reply:I got curious and did a little poking around. Very interesting info.The first link shows exactly what you were talking about. Scroll down and to the right to the "wrinkle bend" section. There is a "next" page to it.http://www.tpub.com/content/construc.../14251_112.htmThe second link just has a short reference to wrinkle bending. http://www.aussieweld.com.au/arcweld...e19/page19.htmThe third is sort of a historical view of back when---------I liked those kind the best. How goood we got it today!!!!!!!http://www.battelle.org/environment/...rinklebend.pdf
Reply:Cool, I'll give this a shot. As far as I can tell, wrinkle bending hasn't been used commercially since WW2, but that doesn't mean it won't work, just that they can afford shinier tools.Thanks!-David
Reply:You could also go to your local plumbing shop and the will bend up to 2" pipe to 90 degrees with their rigid bender.I do alot for the guys here in BC Canada.I also have the rigid bender and it is slick on pipe.Nobody moves nobody gets hurt(safety first)millematic passportmiller 375 plasmacutter
Reply:we have used wrinkle bending to do coils before,  It takes a little practice but it works good.  The best way is with a jig of some sort and a come-along to pull as you heat. If you heat small increments and only pull a little at a time you dont get to much of a wrinkle at all and it is accurate enough for most applications i would say.   good luck
Reply:Here are soem suggestions:1This methoded I learned from a German field engineer doing modificaiton work on an hydraulic die cast machine.     First get your self some dry sand, enough to fill the pipe completely.    Remember dry sand!     Then make up two conical wedges to to trapp the sand in your pipe.   Tap one wedge into the pipe, fill with sand and plug the other end.    You then heat the pipe with a rose bud and bend it to what ever arraingement you want.   You might want to note that he did this wit a good grade of hydraulic tubing but it should work wtih other materials.    I was very much impressed with what he could do and the precision obtained.    Just realize that the sand has to be completely dry other wise you end up with high pressure steam which is not good for you or the pipe.2Bend the pipe cold.    Electrical supply house should have devices called hickies that will allow you to takle 1" pipe.    Don't bother though if you are not a physically big guy or don't have any help.    These are often used in the rnning of electical conduit to fix up alignment.   Not ideal but may work.3If you are extremely carefull you can attempt a segmented bend with a torch.    Do this by heating up a narrow ring around the pipe and giving the pipe a little pressure until it yields ever so slightly.   do this a degree or so at a time over a rather long section of pipe.    This  is probably the least sesirable method as it can be hard to control what you are doing and at the same time get uniform results.Though I haven't done anything lately I truely believe that amazing things can be done with the sand in pipe method.    The only qualification I have is that I have not seen this done with black iron pipe.   Hydrualic steel tubing is a slightly different animal.ThanksDave
Reply:To bend pipe without wrinkling it there is a real cool trick I can tell you about. First you weld a cap on one end of the pipe. Then you pack sand in the pipe except for the last few inches. Then you find anouther pipe that fits into the first pipe tightly and put a cap on that. Then you hammer the capped end into the sand filled pipe very tightly and tack it in place. Then you tack one end of the pipe to your work table and make a jig pattern to bend the pipe around. Then you heat the pipe in sections with the torch and bend the pipe around the jig. The sand will act as a mandrel keeping away any wrinkling so long as you did a good job of packing the sand tight. Good Luck
Reply:Oops Wizard already came up with the sand method. He says he saw it done with hydraulic tubing. We did it with thin wall railing tubing. I think it would work on anything as long as the sand is packed properly. The only time I saw that method fail was once I didn't.The guy who taught me that trick was from Europe too. I was taught by an Italian awning maker with a lot of old world tricks up his sleeve. Ever see someone mix cement on a piece of plywood?