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  1. #1
    Join Date
    Apr 2007
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    347

    Default Curving a Piece of Pipe for a Corral Project

    I need to curve several pieces of 2 3/8 oilfield pipe for a cattle corral project. The radius will be 10' and 12'. I had a local guy roll several pieces for me into 20' diameter half circles and that will get part of what I need done, but it's not economical and scheduling him to do the work is a pain.

    Anyway, I have this grand idea of buiding a press jig to bend the pieces in short sections and the weld them in place. These pieces would be about 8 to 9 feet long and need an arc of about a foot or so. I've already done the CAD work to know the exact dimensions and I have a log splitter with 30" stroke to use as my power plant for the hydraulic press. I'll custom make two press "dies" to get the two different arcs I need. I can make one frame with two different roller pins for the top half of the press frame.

    The only thing I'm unsure of is how much spring back I'll have and how to compensate for it. The log splitter has a 5" diameter cylinder and with 2500PSI behind it, so I have plenty of power to work with.

    Anyone ever done something like this before and have any words of wisdom for me?

    Thanks
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  2. #2
    Join Date
    Jul 2008
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    East Tennessee
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    Default

    If you have a large and heavy enough welding table I'd lay out the shape you want and heat with a torch[rose bud] and pull with a come a long or such. I did this to a piece of 6" pipe at a old job. Much cheaper and faster than making dies. Once I layed out the radius I welded some large angle on the inside of the radius to form the pipe to. Also welded down one end to the table and started the bend from that end. It was really pretty easy.Get a helper so one can heat and the other to do the cranking on the come a long.
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  3. #3
    Join Date
    Feb 2007
    Location
    West Farmington, OH
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    Default

    You might also want to fill the tube with sand to avoid the possibility of crushing the pipe or kinking it.
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  4. #4
    Join Date
    Feb 2008
    Location
    miami
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    Default pipe

    it's hard to believe that what you are proposing to undertake is going to be less costly than finding someone to roll them for you. your time is valuable also. i am aware that this is not always possible if you live away from a city.


    that said you could get some 2 x 10's , screw them together. take a piece of plywood cut it so that it follows the arc and projects about one inch out. this will contain your pipe while you are bending it. lay out your larger radius first. somehow you are going to have to anchor this to something really solid. maybe get some expansion bolts and bolt it to a concrete floor. schedule forty pipe comes in 21's so i would anchor one end a foot or so before the beginning of my template and then attach the other end to a comealong and cold form it over the template. this will work, but life would be easier if you got some schedule ten.

  5. #5
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    Feb 2008
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    miami
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    261

    Default pipe

    stacking two two by ten's will give you app three inches. lay out your pattern on them. largest first; i would layout a little tighter radius than required but it's going to be trial and error. then cut the two by tens to form the radius and then put the piece of plywood or whatever to retain the pipe during the bending process. try not to use any heat; the uneven deformation will be noticeable. you will also lose a lot of pipe because you are going to have to lay your finished product over the correct radius and choose the points that are going to give you the most accurate form; if tyou don't it will look like **** when you weld it together.

  6. #6
    Join Date
    Feb 2008
    Location
    miami
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    261

    Default pipe

    couple of more points; you can make your radius tighter to allow for spring back. it is fairly easy to open something up that has been rolled or formed as opposed to cutting your template several times. i used to layout cam shaped templates so that i could work my metal as i was bending it and checking it against my template.

    also, i said to lay out the larger radius first so that you can use your wood again to for the tighter radius on the second set of bends.

  7. #7
    Join Date
    Jul 2008
    Location
    East Tennessee
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    613

    Default

    Quote Originally Posted by fdcmiami View Post
    stacking two two by ten's will give you app three inches. lay out your pattern on them. largest first; i would layout a little tighter radius than required but it's going to be trial and error. then cut the two by tens to form the radius and then put the piece of plywood or whatever to retain the pipe during the bending process. try not to use any heat; the uneven deformation will be noticeable. you will also lose a lot of pipe because you are going to have to lay your finished product over the correct radius and choose the points that are going to give you the most accurate form; if tyou don't it will look like **** when you weld it together.
    Why not use heat ? Makes it ALOT easier to bend. I'm speaking from experiance.It wont deform if you heat evenly. If your worried about deformation fill with sand as blondie said. Also if you form it to a radius you shouldn't have to choose your points and waste pipe , I never had to waste any.I'd have gotten run off for wasting unneccesary material.
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  8. #8
    Join Date
    Feb 2008
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    Default pipe

    i have formed, hot and cold, a lot of steel and aluminum. heat for bending is always localized. i am calculating, using a chord length of ten feet that would make the included angle between the chord app sixty degrees. pi x d is equal to about sixty three feet. i am working to inside numbers here; custormarily i would be calculating to the mean diameter of the pipe in circumference.

    using these numbers i am estimating the rise from the chord to the underside of the arc at app sixteen inches. this should be not to difficult to bend. if you are locked into the sch forty go for it, but if you can order some sch ten.

    if you rolled semi circles to 20 feet in diameter you had something other than a twenty foot diameter as it would take three lengths of 21 foot sch forty to make the correct diameter. again pi x d.

  9. #9
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    Feb 2008
    Location
    miami
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    261

    Default two further points

    1. we are talking about bending a schedule forty pipe to a radius of 120 inches. elevation from c/l of chord, app 16 inches. this is not a tight bend. therefore we will not be needing any sand. sch forty pipe has app a 5/32 wall. beefy enough to not need any sand.

    2. this whole excercise is about deformation of the steel pipe to get to the specified radius. bending IS deformation. as to wasting pipe it depends on what kind of product you want to put out. as i said earlier. i have done a lot of this. pipe is cheap.

  10. #10
    Join Date
    Feb 2008
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    835

    Default

    Quote Originally Posted by garybdavis View Post
    I need to curve several pieces of 2 3/8 oilfield pipe...

    ...The only thing I'm unsure of is how much spring back I'll have and how to compensate for it...
    2" pipe is all 2.38" OD whether it is standard, extra strong, or double extra strong.

    Without knowing which cross section and grade of pipe, estimating spring back is impossible.

    Accurately predicting springback is a little more difficult. You generally need to run a bending process on a uniform batch of material and measure springback angle for several runs, then use statistical analysis to determine the spread. Material properties generally exceed their specifications and do vary a good bit from batch to batch. Therefore, test runs are the only way to really even get close to the actual quantity you are looking for.

    http://www.thefabricator.com/hydrofo...le.cfm?ID=1607

    Sure, you can whip up a bending die for a log splitter in a fast hurry, but in the time you spent correcting things it can't do well, you could have made a roll bender.

    If you MUST do it yourself, make a roll bender. Just scale up the HF model big enough (and strong enough) to do 2" pipe. You'll need some elbow grease to run it though.
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