pipe bending

By TRC

Date 02-11-2012 19:00

I have done bending in the past using Greenlees one shot benders up to 4". Also done segment bending up to 5". Enough so that I consider myself fully proficient at this task. An upcoming job may require bending of 12" X42/52, .250 wall. Having bending experiance on small stuff and having been a welder/fitter in the gas distrubution business for over 30 years I'm going to offer to do the bending (they have no one else available). I don't have any experience using the transit other than shooting grades so I would have to use string lines and protractors to get my angles just as I would if we were cutting segments.

I have seen bending done and have a general idea what goes on but I'm looking for the details i.e.
Does the machine have a dial or indicator telling how far the ram has traveled?
Is there a wench that pulls the pipe through the machine so your segments can be accurately marked?
How much deformation is gennerally accepted in the pipe wall within the bend zone?
I'm sure the bending machine will be older than dirt -nothing modern from this contractor.
Stuff like that, any info would be great- Thank- Ted

By justahand (*)

Date 02-11-2012 21:57

The machine probabely won't have a dial indicator. What you will do is use a digital level and take a reading in front of the winch do a pull then while it is still under pressure in the shoe you will take another reading. That will give you your degrees.

The inspector should tell you how many degrees in a pull i e 1 degree per foot or 1 degree every 1.5' etc.

The inspector will also state the tolerances on deformation.

You should consider using a mandrel to keep it from deforming

Also once you figure out how high to let the ram go to give you a degree than mark your cylinder so you don't have to measure each time.

The machine should have a wench if not your going to have fun

You will need a side boom to hold the end of pipe opposite the winch so you don't get a rolling offset bend
You will need a helper to keep an eye on the pipe as it comes out the back end Toledo it straight up and down and in turn tell the operator which way to lean the boom

You will want to figure out the middle of your bend and then figure out the degrees desired divide it in half and mark half the degrees before the middle of your bend and then half after.

Don't forget about

By justahand (*)

Date 02-11-2012 21:59

Don't forget about your seams. Run a practice pup to familiarize yourself with the machine. Good luck

By TRC

Date 02-11-2012 23:30

Thanks Justa. Does the machine have to be level or do ya just do the math for the angle?

By pipehead (***)

Date 02-12-2012 00:33

I have done quite a bit of bending on a shoe and with a machine with and without a mandrel my advise with as expensive as pipe is right now steer clear! There is alot too it more then just the math it takes alot of feel to become familiar with the machine and pipe to keep from wrinkling it.

Just my two cents if you want you can PM me and i can put you in touch with some true bending engineers that might could help you.

By justahand (*)

Date 02-12-2012 00:49

No the machine doesn't need to be level but the closer the better so that your not fighting to many variables at one time. Usually there us a close enough to level area near your bend. Just put your pipe in do a pull get a degree or a degree and half whatever the inspector wants then before you release the pressure from the shoe check with your digital level on the winch side and subtract from the back side which if you need to get a high number of degrees will end up being in air pretty high so get your ladder and your help to hold it for you.

On a different note if you have to engineer the bends, over bends, sags and rolling offsets than you could be in for quite a ride. But if someone has already engineered it then practice on a pup piece to get familiar with your machine then have the inspector there measuring the deformation and telling you how many degrees per pull.

And really watch your seams as they need to be on to be on top.

Operating the machine isn't that hard but I've never worked with a mandrel Ice bent 8",6" and 3" with a machine and a shoe. I also agree with Pipe head about the engineering part that can get tricky but it's not too complicated if you can work with an old timer to show you the tricks.

Also don't forget it's not just bending but you also got to account for overlapps in the pipeline and you have to be on the stringing crew to string the pipe proper. So there is alot to consider

Also

By justahand (*)

Date 02-12-2012 00:55

Also keep your last pull Ag least 5' from either end which only gives you out of a ~40' joint 30' bendable pulls which depending on the inspector could get you 30 degree per joint or less. Now you also must consider you right off way and the amount of room you have at your disposal at the PI. Also you need to ask how much the contractor wants you to follow the Kay of the land with overhangs and sags or are they going to rope it in and just want you to bend the drastic stuff.

Good luck show us your work.

By TRC

Date 02-12-2012 01:50 Edited 02-12-2012 02:06

It's a distribution job 5500' down a winding secondary road thats relatively flat. The bending will only be a few degrees to follow the road. The tie-ins will be done with fittings. Completetion date is September 1st so we won't start with the 5 man crew until August 15 or the 20 Hahah!

Pipehead, are wrinkles or buckles caused by trying to bend to much at one time? IF they elect to use a bending machine we do have some pipe in the yard that I could do a couple practice bends with. Really appreciate your responses- Ted

By pipehead (***)

Date 02-12-2012 02:52

Yes to much pull or also your pulls being to close together especially .250 wall, also keep an eye on your coating putting pipe in and out of that machine they can create alot jeeps. Alot of the machines will have some what of a gauge but the are primitive and not real accutate but bieg that you are running .250 i am guessing your inspector will only make you bend anything over about 5 or 6 degrees