Bending Black Iron Pipe in a Gentle Arc

I would recommend using angled pipe fittings with a good sealant on them. Anything that is used in flamable situations when using rigid pipe is not allowed to be bent for fear of stress fractures. I believe it is also in the NFPA code book as well.

Not a good idea at any rate especially when the fitting in black pipe ar not that much.

Just get a couple of 45deg and you can have you bend without compromising the piping.

Makes sense. Thanks.

No Problem glad to help.

If you get a 20ft section you should be able to do it. I used wooden stakes to assit me with an arc when I bent one years ago to go around a huge boulder.

I would use pipe fittings to direct the pipe where you want it to go.

bending an arc like that takes quite a bit of tweaking to get it just right to make the threads of your fittings to line up well enough to thread them together from on pipe to another.

With the fittings everything stays straight so the ends will line up appropriately.

Yes you can bend it, but you'll need to draw an arc on the ground and check your bend repeatedly to see that it matches the arc. It's a time consuming process, that would have been done already by using fittings, when checking to see if your arc is correct after your first attempt at bending.

Also when you bend pipe, you're going to get some distortion to the inside radius, it would be advisable to take the pipe to a machine shop and have it rolled, rather then bent.

I have been involved with bending some light angles and radiuses on ERW (black iron)pipe in the past and it worked very well. Most pipe will tend to flatten out way before it cracks when trying to bend it. Sometimes on tanks or in very tight areas there is just no other way to get from point a to b without a bend. One thing you might consider if you are worried about cracking is to upgrade to SA106 grade B seamless pipe for the bent portion. Another thing is to apply a pressure test on the system at an increased pressure to insure you have no cracks after bending. This is routinely done on most piping systems with water or air pressure after construction is complete anyways. Allot of high pressure hydraulic and lube oil piping is done with all bends so that the long radiused ells have less restriction as well as to eliminate as many extra welds as possible than using normal ells. I worked on several steam turbine installations where we ran the oil piping with 5D radius bends.

pipewelder

we bend 3/4" pipe all the time even in tighter radius. 150 to 550 psi natural gas pressure is common. Probably much more that the LP pressure you will be using. We do cold bendswith the pipe laying in the ditch one person pulling or puching the pipe against the dicth wall and a shovel.

You have been afforded some very good suggestions here. However, one that was not advanced is the use of that orange plastic pipe normally used for gas service. It is flexible and well suited for the service. Bending the black iron pipe does present the dilemma of having to thread the pipe onto the next fitting or section of pipe. Could present a problem.

Thanks for that suggestion. What is that orange plastic pipe called in the trade and can you confirm it is good for LP service?

I just found online at a DOT site that the only plastic pipe approved for LP service is yellow Polyethylene pipe conforming to ASTM D2513. I assume that is for low pressure (inches wc, which is my application) as well as high pressure. The reference made no mention of pressure.

oyacetelyene welding works great

If the fittings are available that is the easiest way to go. If you are in an isolated area, such as being at sea then you do what you have to.

One trick to bending pipe is to prevent the pipe collapsing. The way I was taught was to seal one end of the pipe, fill it with dry sand and seal the other end.

Small diameter pipes bend easily cold.

Large diameter require heating.

Large thick steam pipes require lots of heat, big chain blocks, lots of jigging to locate it and lots of suitable adjectives to encourage it to conform to the will of the engineers.

BAB

rponds,

in the previous century (1800's) it was fairly common for plumbers to bend the gas piping in homes to get around obstacles in walls and ceilings. (Gas was supplied to every light fixture while electricity was considered too unreliable!) Rigid electrical conduit has the same size and thread specifications in the USA as black iron pipe. Bending black iron pipe is easy with a standard electrician's hand bender; use one sized for the next larger thinwall size. Thus, you would use a 1-1/4" bender to do any desired bends in the 1" pipe. These benders have sides on their shoes which minimize any flattening of the pipe being bent.

You can achieve a sweeping arc by calculating the circumference of the section to be bent and then doing 5-degree or even 10-degree bends spaced uniformly apart along this circumference. You can even thread a straight piece almost wrench-tight, do all the bends, and then finish tightening it so it lays in the ditch as desired. If you can't do that, butt the bent piece to a previous straight piece with a coupling on its end, then unthread the coupling so it is half on each piece of pipe, then turn the new piece until it is wrench-tight (perhaps 6-10 turns will be needed) and the pipe lays properly in the ditch.

Regards--JMM

Very good to know. Thanks!