Introduction: How to Bend Pipe Without a Pipe Bender

Picture of How to Bend Pipe Without a Pipe Bender

Ahoy! So you have some pipe that needs to be bent but you don't have a pipe bender. Well no problem! This instructable will show you how to do it using sand and some creativity. 

The pipe shown here is 4130 steel - 3/4" in diameter with a wall thickness of 0.035".

The point of using sand is to support the pipe (keep it round) so that it does not buckle when bent. It worked for me!

Plan ahead - the end closest to the bend will likely have to be cut off and discarded.

Step 1: Pack Your Pipe

Picture of Pack Your Pipe

The first thing to do is to plug one end of the pipe.  I used a small carriage bolt that fit snugly in the end.  The next step is to fill the pipe with sand.  I used beach sand.  The sand should be nice and compact to stop the pipe from buckling. I used a rod to tamp the sand but what really packed it in was tapping (bouncing) the pipe on a concrete paving stone. 

Step 2: Bend!

Picture of Bend!

Clamp one end to a form. Here I used a wine barrel planter and then added a rounded block (that just happened to be in my workshop) to get a tighter radius.  You will likely need a lot of leverage to bend the pipe. This piece was 4 feet long and it took some muscle to get the bend.

Step 3: Finish It Up

Picture of Finish It Up

Cut the deformed end off. Clean out the sand. I used a piece of string with a rag on the end to get all the sand out.

The picture below shows the slight dimple in the center of the bend.  Unfortunately the method is not perfect but I am very happy with how this turned out (the pipe is a new steerer arm for my bamboo box bike )

One last thing - you can heat up the pipe with a torch before bending to soften the metal and get a cleaner bend.  I did not want to mess with the temper of the pipe so I did not do this.


justin367 (author)2016-02-19

Can you use this technique on a 2 inch pipe.

strayturk (author)2013-09-11

Very nice tutorial, thanks!

My inner perfectionist wants to provide one correction, with your permission. The material you used (the 4130 steel) is most probably considered a tubing, rather than pipe. The difference is in their measurements and intended use. You measure a pipe by its internal diameter and you don't worry about wall thickness, whereas a tubing is measured by its outer diameter and wall thickness.
For all practical purposes, the bending method you described would apply to both.

Have a perfect day! :)

kwhit190211 (author)strayturk2013-09-16

I've worked with pipe for 39 years, sir. And you definately have to worry about wall thickness. Your right about one thing, though. You measure pipe by inside diameter that is, up to 12", 14" pipe you measure by OD (outside diameter). Plus, not all tubing is measured by outside diameter, either.

bowen5400 (author)kwhit1902112016-01-31

Wall thickness, type of pipe material, copper, steel etc., diameter, and angle desired. All have at least some effect on bending characteristics. Sand or salt? Why salt, such a mess, so corrosive, etc. . Heat is tricky, too hot for copper is just right for steel and so on. Water with sand? That is pretty risky except for specialized circumstances and equipment. I agree, never use water especially if the ends are plugged airtight. Seems any pipe sealed airtight is risky with heat. Sand can be damp enough, or just air expansion itself, again depending on size, material, and wall thicknesses. I guess one of the big issues on a blog like this is the wide range of people with varying projects that might read the advice here.You guys are so helpful, with your professional, industrial experience. Thank you for your info.

ayasbek (author)strayturk2013-09-11

Yes! Thank you. I love info like this.

antioch (author)strayturk2013-09-11

Indeed, nice tutorial on a clever idea.
Thanks for your addition, too.

altomic (author)2013-10-18

thanks,nice instructable.
I watched a doco on making slide trombones. to make teh bend they filled the pipe(brass) with briney/salty water. sealed each end with corks and then placed it in a larger freezer. once the briney water had gone almmost hard (it won't completely freeze or they didn't allow it to freeze) and that's when they bent it and it didn't crinkle.

kwhit190211 (author)altomic2015-08-23

They used this method in bending because that tubing is very thin and if you filled it with sand instead. You might end up with a wrinkle bend, that's definately not good for the instrument.

clubagreenie (author)2013-09-10

Sand bending has been used for decades for all sizes of tubes being bent. Not just small stuff. You need to wet it out to get it to compact, but one end (usually the long end away from the bend) needs to be left open regardless of if you;re using heat or not. When you heat it if sealed it will explode and hot sand burns aren't fun (ask a foundry worker). When you bend it sand will need to be displaced and go somewhere so one end needs to be left open.

If doing multiple bends you need to resettle the sand between bending or you will kink it. Voice of experience. If you look at the elaborate designs in F1 exhausts etc from the 70's and 80's (pre titanium days) hey were all done by hand from one piece of tube.

pictsidhe. (author)clubagreenie2015-05-06

Wrong, much like the article. If you heat, you need to let the gas out. If you let the sand out, the pipe will kink. I weld one end shut, weld a large nut on the other, then bang, rattle the sand down before finally screwing a large screw as tight as i can into that nut. The pipe has to be packed very hard to prevent kinks.

kwhit190211 (author)clubagreenie2013-09-18

Wrong!!! if your going to use sand in tubing or pipe to heat bend it you do not add water to it!! That will produce steam which is 212 degrees, hot!! To compact the sand, just hit the pipe with a hammer while filling it & the sand will compact, tightly. Never but never add water to sand to do heat bending.that "short cut" is going to get you hurt!!

ecurtain (author)2013-09-19

Oh, this is great -- I'd never seen it before, thanks.

Eh Lie Us! (author)2013-09-19

Whoa. I just learned something today.

spiderham (author)2013-09-06

1" thick wall pipe will bend fine without the sand. I bent multiple 90s using pier footings as my form for an air line install I did a couple years ago.

kwhit190211 (author)spiderham2013-09-18

your right, you don't need sand to bend pipe, it's just if you have to bend a tight radius is when your'll need it!!

randomray (author)2013-09-10

Chuckle , this method has been used by pipefitters and plumbers for probably more than a hundred years . But it's good that you're getting it out to more people . You can also keep the end of the pipe or tubing from deforming by putting a pipe or tubing coupling on the end and clamping to that .You can put a pipe plug in the coupling to hold the sand in too .If you do need to heat it for a tighter bend make sure the sand is dry and there's a way for the steam to escape . Otherwise you can end up with a pipe bomb ... a very bad thing :-(
Thanks for sharing .

kwhit190211 (author)randomray2013-09-16

When I was still working as a Pipefitter (retired now after 38years). Whe always plugged the end of a pipe with a rag. Then pour the sand into the pipe, while hitting the side of the pipe with a ball pein hammer. That packs the sand in tight. Once the pipe was full bt this method we sealed the other end with another rag. But, we only packed them with sand if we were bending a real close radius bend. Usually we never used sand. We just bent it empty, coarse we had a large bending table with pins to put the pipe between to bend.
When bending pipe you want to make sure that the pipe is level or you can end up with a twist in it. And, they are hard to get out.

randomray (author)kwhit1902112013-09-16

Yes , but this is for people who don't have a bending table or a hydraulic bender in the workshop I was just adding information that might help a home mechanic as would your info about using the rags to hold the sand in .And yeah I've been a pipefitter over 30 years .

kwhit190211 (author)randomray2013-09-16

Understandable. When I use to bend pipe, other than putting rags in the end. If the pipe to be bended was screwed I would always put a line coupling on one end with a plug in it & a sleeve with a "cheater" screwen into the other end to add length to the pull. But, all in all, if your not making a close radius bend, you don't need the sand.
And, as someone here has stated they use salt. Well, I've lost tract of how many feet of pipe that I have burned out that was clogged with salt over the years. We always ran into it with air lines bent around the bustle pipe of a blast furnance.

randomray (author)kwhit1902112013-09-17

I always thought the salt was so you could dissolve it with water if it got packed in too tight .

kwhit190211 (author)randomray2013-09-18

It all depends on the location, concerning salt. I know that it can form a concrete like plug in pipe. And, you can't always have the time to wait for it to disolve. When they want it now, they don't want it tomorrow the wanted it like yesterday. As a Pipefitter, you are always on a time schedule. And, just because they are a boss, it doesn't mean they are smart!!

kwhit190211 (author)kwhit1902112013-09-16

And, believe it or not there is such thing as a wrinkle bend. Where the wrinkles are figured into the bend. While in all the years that I worked as a Journeyman Pipefitter I have never used it. We had to know how to make it when I was a apprentist. It's just like one of those things you have to learn in school that you never use.
Case in point, I'm 66 years old, I've been out of grade school for 47 years, and during all those years out of school I have never needed to diagram a sentence, yet!!!

randomray (author)kwhit1902112013-09-17

Ha ha , yeah I can't remember diagramming a sentence since school either . The math and geometry have helped out many times though . Not that much pipe bending going on any more , of course it depends where you work . It's mostly tubing . They get so they require stress relieving most pipe bends and welds where I worked .

spylock (author)2013-09-14

I thought only us older dudes knew about the sand to keep the pipe from kinking trick.So heres a tip some of yall may not know about,the best way to mix cement is in a tarp,one of those cheap blue tarps work really well.You can have a bag of cement mixed in no time flat,and perfect,you just add water as needed,mine comes out perfect every time.I have many good ideas to put up if I ever get the time,like the shoot and see target from a disposible plate on the cheap.And many more.

arty (author)2013-09-12

Pipes can be straightened or bent by whopping them deliberately against a carpet covered tree stump. I have straightened a a combine-harvester drive shaft this way. I have bent plumbing pipes this way. Swing slowly and firmly. It is okay to bend too much or too little. If you over-shoot, turn it around and thump it again to take out the extra bend. I've been doing it this way since the mid '70's.

elic (author)2013-09-12

Very nice. I saw this method on a 1965 film - Flight of the Phoenix, but I have not idea that it was possible.

kitkatgreenfish (author)2013-09-11

Brilliant! Love it!...Huggs.....Kitty

spark master (author)2013-09-11

If you have the right sized ubolt , attached it to the end where the pipe is secured. This gives you the ability to not crush the end. If you have welder, take 4 of them line them up weld them on the outer side, cut off the arms on all but one (or two ends if you feel the need) so you have a tunnel of sorts, no welder, ,,,, take a piece of next size pipe cut a slot about 1 inch long then lop it off so you have two halves attach ubolt to the barrel leaving it loose, push pipe in use 1 of the pices as a shim on the side that will buck up against the ubolt. tighten it so the tube to be bend can move ever so slightly.

Now when you slide in the pipe/emt you have a finished round surface. You could epoxy the pipe slice onto the ubolt.

gnach (author)2013-09-10

As you found out, clamping at the end smooshes it out of round. Try securing your clamp a little further back. I've had good luck with gentle bends like yours by sliding the pipe under a care tire, just wedging it tightly, and lifting carefully. Slide it "in" a little deeper each time but be careful not to pull too hard at any one point. The tire cushions and supports the bend. Also it's easy to roll the pipe and get off plane causing a twist, just pay attention. Thinwall tubing is more problematic than pipe but it's doable.

papabikemike (author)2013-09-10

You need not have worried about hurting the heat-treatment of 4130. It is a relatively low carbon steel (but high chromium and molybdenum) that maintains a high percentage of its maximum strength during air cooling. It was originally meant to be torch welded as critical airplane structure without post-welding heat treating.

ayasbek (author)papabikemike2013-09-10

good to know! thank you.

billbillt (author)2013-09-10

great idea!

rfcalloway (author)2013-09-10

very nice!

kc0kfg (author)2013-09-09

Please if you decide to use heat to bend your tube, make sure your sand is dry,,, no Very dry!
Wet sand trapped in a tube add heat, is a huge risk.

fzbw9br (author)kc0kfg2013-09-10

as long as you don't weld the ends shut, even damp sand will vent.

but with sand, heat is not necessary at all.

chairchild (author)2013-09-09

At such a low angle, you could also just clamp it (as you did) and bend it round gently :) Filling pipes with sand only makes the job harder, it annoyingly doesn't actually improve anything

fzbw9br (author)chairchild2013-09-10

if you have ever tried to bend thin pipe, even gently, you have for sure put a kink in one.

Sand just helps eliminate that hazzard.

tootall1121 (author)2013-09-10

Now this is a useful idea. Sure, it's slower, but if you only have one job to do, maybe something you're just messing with, a great way to get it done. I do believe this would qualify for being "The Mac Gyver way."

fire (author)2013-09-09

I've also had great luck using salt (not sugar!) with 1/4" soft copper tubing. You can use hot water to dissolve the salt when you're making tight bends, such as forming a condenser coil.

vegasrandall (author)2013-09-09

you can also use frozen water,pitch,or wood's metal ( low melting point alloy)

Jackoffmanytrades (author)2013-09-09

As long as your careful the pipe won't kink anyways. Good tip if you have the time to do it. But bending in steps will accomplish the same results.

wilgubeast (author)2013-09-08

Smart technique for bending small diameter pipe. This is a project that'll appeal to a lot of dilettante benders out there. In fact, I'm trying to think of any opportunities to make use of this technique around the house. Maybe some of those cutesy/industrial pipe shelves, but bendier? Hotel-style bent shower curtain rod?

oldmicah (author)2013-09-05

Ha. I hadn't seen that used for steel pipe...nice! I'd used hot sand to do a similar thing with PVC.

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More by ayasbek:How to bend pipe without a pipe benderHow to make a vented coat hanger for a wetsuitIntro - How to Design and Build a Bamboo Cargo Bike (Box Bike - Bakfiets).
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