Cold bending of straight pipe
Cold bending of straight pipe
(OP)
Is there a formulation, where by we can calculate as to max bending degree of a 20 inch OS diameter pipe of standard 12 meter length and how it can be corelated practically.
Menon
Menon





RE: Cold bending of straight pipe
This type of work requires special tooling and bending equipment and considerable experience, not just some formulation. It is highly dependent on the strength of the pipe steel and the wall thickness vs. the pipe dia., etc. I would talk to a local fabricator who does this type of work regularly. Google pipe and structural shape bending, there are a number of companies doing this kind of work.
RE: Cold bending of straight pipe
Pipeline bending is typically done to an inner radius of either 40D for a field bend or 3D or 5D for a hot formed bend.
I once did 10D for a cold bend, but it needed special treatment and sand packing to stop it wrinkling.
For a pipe of 12m long, leave at least 1m at each end. Then your angle is simply an arc of radius 40 x D, 10m long.
Circumference of your arc is 40 x d(in m)x 2 x Pi. Angle is ( 10 / circumference ) x 360.
Is this what you meant??
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Cold bending of straight pipe
FIRST and before ANYTHING ELSE find some one in your area or the fabrication area who already has the machining, the cranes and layout tables for 20 inch pipe, and the transportation to get the pipe to and from his shop to where ever you need the bent pipe. That company (for a twenty inch pipe capacity) has invested many tens of thousands in a machine not often used. Expect to pay a lot.
THEN, ask that company how far they can bend successfully and reliably 9or with what number of failures to successes for each bend diameter. Far, far more than steel welding, pipe bending is an art that doesn't always work. You will find the roller and foreman far more important than the company salesman. Do NOT believe just thumbrules - skilled rollers will be able to break thumbs and thumbrules.
Specify a bad setup, you WILL pay for the many failures between each successful bend. Set up a good, easy, well-practiced bend on a table and machine capable of that work, and you will get good bends all day every day.
RE: Cold bending of straight pipe
The forces generated on the rollers are going to be very large if you want to end up with a proper bend and straights due to the short distances to be used between rollers depending on the bending radius you are after. In case you use large distances between rollers although the bending radius require short distances you will not get the proper bending shape, the pipe will bow immediately from the rollers. So the shape and strain control will be difficult. The spring effect is another to be considered.
You can find simplistic equation for beam bending curvature and stresses created:
www.freestudy.co.uk/statics/beams/beam%20tut1.pdf
RE: Cold bending of straight pipe
www.eng.uah.edu/~wallace/mae466/DOC/bas_str.pdf
www.personal.psu.edu/juc47/Course/EMET222/BDupenBo...
Just to remind you the calculations are here and above are valid in elastic range.
For plasticity you may consult Roark's Stress and Strain Handbook.
RE: Cold bending of straight pipe
http://www.google.com.au/url?sa=t&rct=j&q=...
However this is for the I beams, but will give you the in-light of cold bending.
RE: Cold bending of straight pipe
(Section slenderness limits of very high strength circular steel tubes in bending)
http://www.google.com.au/url?sa=t&rct=j&q=...
RE: Cold bending of straight pipe
Per the specific question posed in the OP, the included bend angle possible with a 20" OS dia pipe would depend on the pipe wall thickness, the CL bend radius required, how much thinning is acceptable in the outer pipe wall at the bend, and how much deformation is acceptable in the inner pipe cross section at the bend.
RE: Cold bending of straight pipe
It's going to take a lot of lead.
RE: Cold bending of straight pipe
https://www.google.ae/search?q=pipeline+bending+ma...
I hate Windowz 8!!!!
RE: Cold bending of straight pipe
The biggest problem these days may be finding the men not the machinery.
B.E.
You are judged not by what you know, but by what you can do.