Pipe Bending and Tube Bending: What Sizes Go On What Machines


Pipe bending and tube bending can be achieved in various ways.  Factors to be considered include the size of the pipe or tube to be bent, the wall thickness, the desired radius, and, of course, the material.   Then there are the equipment and methodologies available as well as the skills of the machine operator.  By the skillful match of material, machinery, methods, and talented operators, a wide variety of bends can be achieved with great accuracy and appearance.

Perhaps the most common method of pipe and tube bending is done on what is called a “rotary draw bender.”  Round pipe, as well as round, square and rectangular tubing, is clamped into a form and drawn over a die with the desired radius.  Each die must conform not only to the desired radius, but also to the outside dimensions of the material to be bent.  Once set up, however, the method can produce quality parts relatively quickly.  And the radii can be as tight as two-times the diameter of the pipe.  The maximum limit on the outside diameter of the pipe is usually 10in; the minimum limit might be 1/8in or smaller.

Pipe Being Curved by Rotary-Draw Bending

Seldom used in construction, these curved parts are commonly used as component parts of equipment, e.g. tractor parts, process piping, and bollards.

Stepping up in capacity, three-roll benders (also called “section benders,”  and “angle rolls”)  can bend pipe and tubing up to 24” OD  pipe and 20×20 tube.  Rolling sizes this large is not that common; a more common range would be from 2in to 8in outside diameters.  With this method, pipe or tubing is passed through 3 or more rollers which induce the curve at the point of contact.  The parts are rolled back and forth until the desired radius is achieved. Multiple dies are required to hold the outside diameter of the sections, but the three rolls can be manipulated to create a very wide range of radii.

20in Outside Diameter Pipe Being Curved

Three-roll benders are used to create parts for equipment as well as sections curved for construction.

Lastly, the largest pipe and tube sections can be bent using induction bending.  An electric coil heats a small section of the pipe or tube while machinery pushes it to a swing arm that induces the curve.  Water cools the section once it has been bent to the correct radius.  Pipe up to 66in in diameter can be bent.  The process can also provide close tolerance tight bends.

Induction Bending

Applications include processing pipe, component parts of equipment and curved structural members.

As you can see, there are a variety of methods to bend pipe and tubing, and part of the decision-making process is choosing the equipment right for the job.

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