Bend pipe into a 'U'?

May 1, 2007 8:49 AM

I want to bend a metal pipe into a nice U-shape. Is this possible to do myself? If not, what type of company would be able to do this for me?

The pipe would be 1-2 inches in diameter. Steel or what is used in boiler systems. I assume i could rig something up with a hydraulic jack, but i worry about the pipe pinching and folding and not giving me the nice gentle U-bend.

(I also wonder if the pipe will shatter and blast metal fragments into my eye or something.)

I only want to bend 2 pipes, so i'm not sure if it would be possible to go to a company or professional. I tried welders, but they couldn't help. Any other suggestions? (I'm in Toronto, btw.)

posted by kamelhoecker to technology (21 comments total)

This might help. You might find something similar in a local hardware store.

A plumber might also be able to help you without you having to purchase a device.
posted by odi.et.amo at 8:54 AM on May 1, 2007

Any local machine shop should be able to do it for you. Some muffler shops probably can, too.
posted by rfs at 8:55 AM on May 1, 2007

Can you not buy pipes that are manufactured in this shape? Seems like the craftsmanship involved in keeping the bore perfectly round would have to be pretty skilled.
posted by hermitosis at 8:57 AM on May 1, 2007

An auto shop that does offroad/race/rally work like roll cages, tube fenders, etc. could do it too.
posted by FuzzyVerde at 8:58 AM on May 1, 2007

I've seen several discussions of filling pipes with sand in order to bend them without crimping them.
posted by OmieWise at 9:06 AM on May 1, 2007

You can certainly bend pipe using a hydraulic rig, but I’d be more worried about catastrophic failure in the rig than the pipe. Also the diameter of the pipe doesn’t really matter as much as the gauge or thickness of the pipe. For steal piping this is often referred to as “schedule foo” the thicker the pipe the harder it will be to bend. A pipe of any considerable thickness will be very strong and creating a rig strong enough to withstand the forces you’d be applying to it might be more difficult than just finding a metal fabrication shop or a plumber or a custom auto body shop who would have the equipment to do what you need. If you were going to bend 20 pipes I’d say do it at home, for just two they should be willing to do it for a nominal fee.
posted by French Fry at 9:08 AM on May 1, 2007

Here you go, an instructable on How To Bend Tubing.
posted by OmieWise at 9:09 AM on May 1, 2007

I can't imagine that this will be a problem with steel pipe, but for pipes with thinner walls (which would otherwise buckle) the trick is to fill the pipe with something which is not readily compressable but still allows the pipe to be bent, and can be readily removed after bending. Pitch is traditional for brass insturments, and I think I've heard of using sand or soft, low melting alloys.
posted by pullayup at 9:10 AM on May 1, 2007

I tried to make snowshoes by bending sand filled aluminium pipes and failed miserably.

No, low iron steel pipes are ductile, and will not shatter and blast metal fragments into your eye or something. Unless you are trying to make glass tubular bells, you are safe.
posted by racingjs at 9:10 AM on May 1, 2007

crap, that's compressible.
posted by pullayup at 9:11 AM on May 1, 2007

I would seriously recommend going to a muffler shop. They can do these bends, and can probably sell you the pipe too. Go when it's not busy, and be friendly. Explain what it's for. I imagine many of the people working in a shop would enjoy the challenge of something different like this.
posted by cosmicbandito at 9:25 AM on May 1, 2007

You are looking for someone who does hydraulic mandrel bending. Madrel bending assures a clean, kink-free bend without any pinches. Most good muffler/exhaust shops should do it. Alternatively, any shop that does a ton of customizing work should, as should any shop that builds motorcycle frames.
posted by Thorzdad at 9:47 AM on May 1, 2007

I tried welders, but they couldn't help

Were you trying guys that are just "welders"? Because my first stop would be a steel shop (metal fabricator might be another term to look for). They bend pipe all over the place for stair railings and stuff like that. Your U-bend will probably take them about 5 minutes.

If you end up going with copper pipe (for a boiler), try a plumber.
posted by LionIndex at 9:49 AM on May 1, 2007

If you live near a university (better yet if you attend the university) with a mechanical engineering department, you might try to call the machine shop operator. He might even do it for free and let some students have a go at it.

Lately I've been fearing graduation because I'll lose access to an awesome machine shop!
posted by JacksonEsquire at 10:44 AM on May 1, 2007

If you're talking about pipe designed to handle steam pressure, it's going to be thick wall, and it's probably going to be galvanized.

It ain't gonna be easy to bend without heating it up, and there's a chance that the nickle plating will flake off. I would say that this is something you should let a pro do.
posted by Steven C. Den Beste at 12:23 PM on May 1, 2007

First of all, there is a big difference in difficulty between bending thinwall steel tubing, like engine exhaust tubing, and bending pipe. Muffler shops often have hydraulic benders with dies for bending steel exhaust tubing, but this equipment would not be suitable for bending equivalent diameters of steel pipe.

Next, when bending pipe, there are big differences in bending various materials out of which pipe can be made. Rigid aluminum electrical conduit bends differently than equivalent steel conduit, which bends differently than stainless steel, which bends differently than equivalent diameter black iron pipe.

Finally, there are significant differences in the force and sophistication of equipment needed for bending various diameters of pipe. You can buy hand tools for bending and threading 1/2" and 3/4" diameter steel conduit and black iron pipe at any hardware store. You can tackle 1" and 1 1/4" diameter conduit with such manual tools too, if you're the hefty sort, but doing a full 180° bend with such in the larger diameters would require tremendous skill, and the strength of Charles Atlas, even with long lever handles, and such tools are never intended to bend 180° bends in the first place, for reasons I'll explain in a minute. To bend 2" diameter pipe you will definitely need a power or at least a hydraulic bender.

Next, 180° bends in steel conduit or black iron pipe are very rarely, if ever, done in trade. In electrical work, it's impossible to pull wire through such a bend, and such bends are prohibited by code in conduit design, where the maximum bend will generally be specified as 90°, and if more than 1 is needed in a given run, cast fittings with pull plates are required to provide access for damage free pulling of insulated wires. In plumbing and steam fitting, bends of over 90° are likewise infrequently allowed by code, and when allowed or required as in fluid traps, are usually handled by cast fittings, which are sometimes required to have access ports for clean out, analogous to pull plates in electrical fittings.

So most commercial bending machines are going to have 90° bend limits, with minimum radiuses calculated for such. 180° bends would have much greater minimum radii, to prevent kinking of the conduit or pipe by spreading the deformation over a much greater lineal dimension.

So, my suggestion would be to carefully specify what materials and wall thicknesses you need, and the minimum bend radius you need, to first decide the feasibility of trying to find a bending fabricator at all. If you can't decide about this, talk to professional fabricators, and be prepared to disclose details of your application. If the parts you seek can't be produced as bends, you might still get weldments made, or at higher cost, even have custom castings done.
posted by paulsc at 12:36 PM on May 1, 2007

To help you when making your phone calls looking for a place: you are looking for a "fab shop" with a "tube bender." What you want is a really skilled fabrication shop that does a lot of work with tubing, such as off-road vehicle roll cages, dune buggy chassis, play ground equipment, etc.

If you need thick walled tubing, a muffler shop won't be able to help -- their equipment is for thin tubing only. But if the thin-walled stuff will work for you, a muffler shop will probably be cheaper than any other option.

Paulsc is right -- knowing the specifications will help in figuring out who to call. The other way to get to the same result is to say, hey, the tubing I want is about the thickness of the tubing in a roll cage and needs to be really strong, so I'll start by calling shops that specialize in off-road vehicles and ask who is doing skilled fab work locally; or, hey, the tubing I need is pretty slim, more like what I saw in the railings on that building on campus, so I'll call the building department and ask what metal fabrication contractors they are using. Once you know how to describe what you are looking for, you will be able to figure out who to call.
posted by Forktine at 1:33 PM on May 1, 2007

yes, "tube bending" is the magic term! That was a huge help.

I now realize that the people bending roll cages and motorcycle frames should be able to do this easily. I just have to find a shop that will do such a small job.

The muffler shop is also a great suggestion. I'm going to check one out tomorrow, but I expect their tubes will be too thin. (I need this for a bicycle stand, so ideally it should be as strong as possible.)

Thanks the help.
posted by kamelhoecker at 4:15 PM on May 1, 2007

and there's a chance that the nickle plating will flake off.

The metal used for galvanization is zinc. If you are heating the pipe enough to get a bend it won't flake off, it will come off as a vapor. And it's wonderfully bio-available. Good news: It probably won't kill you. Bad news: You'll wish you were dead. It feels like having a steam locomotive parked on either temple while men with mutton chop sideburns drive a gold spike into the top of your head.

Linsay Publications sells a book on making a pipe bender but I think they're using a hard wood die and bending things like conduit and copper tubing. You could scale it up, but for two that seems like a lot of work. Harbor freight sells a pipe bender that has to rollers on either side of a ram with a curved channel in it. I doubt it will do a two inch pipe though.
posted by Kid Charlemagne at 4:17 PM on May 1, 2007

This guy will do it for you, too.
posted by Thorzdad at 4:42 PM on May 1, 2007

Kamalhoecker,

However you solve the pipe-bending problem, please post the info here. I, too, am in Toronto, and would prefer to lock my bike to a beefy u-shaped steel tube (instead of using the front porch, as I currently do).
posted by asfi at 1:31 PM on May 18, 2007