Tube & Pipe Bending Processes and Terminology

Common Methods of Pipe Bending & Tube Bending

Rotary Draw Bending: This is the method of bending in which pipe or tube is bent using a combination of dies and other various components working in a rotary action. This action draws the pipe or tube forward making the desired bend in the pipe or tube. Rotary draw bending can also utilize mandrels. See Mandrel Bending below.

Compression Bending: This is a method of bending pipe or tube where the die in place stays stationary while a counter die bends the material around the stationary die.

Mandrel Bending: In this process a mandrel is placed inside the tube or pipe that is being bent, especially with thinner wall materials, in order to prevent defects that can occur in the bend of the piece such as rippling, flattening, or collapse.

Roll Bending: This method is used when large radius bends or curves are required. A piece of pipe or tube is passed through a series of three rollers that are in a pyramid configuration.

  • Rotary Draw Bending
  • Rotary Draw Bending
  • Compression Bending
  • Mandrel Tube Bending
  • Roll Bending

Common Materials Used for Bending:

  • Ferrous Materials: Steel, steel alloys, and stainless steel. These are materials the are primarily from iron.
  • Non-Ferrous Materials: Aluminum, copper, and nickel. These materials are made from other ingredients other than iron.

Common Pipe & Tube Bending Terminology


Tube or Pipe Outside Diameter

O.D. = OUTSIDE DIAMETER:* The measurement across the widest area of a pipe or tube.

*It is important to note that the measurements of pipe and tube are called out differently. Read about the differences in  Pipe & Tube Measurements

I.D. = INSIDE DIAMETER: The measurement across the widest part of the inside opening of pipe or tube
Tube or Pipe Inside Diameter

WALL THICKNESS:  The measurement between the outside and inside surfaces of the pipe or tube.

GAGE: Gage refers to the wall thickness of metal tube.

SCHEDULE: Schedule refers to the wall thickness of pipe.

DEGREE OF BEND: The angle at which the pipe or tube is required to be bent.
TANGENT = The straight portion(s) of a bent piece of pipe or tube. The tangent starts where the bend ends.

C.L.R. = CENTERLINE RADIUS: Radius along the centerline of the pipe or tube to be bent.

C.L.D.= CENTERLINE DIAMETER: The measurement across the whole part - centerline to centerline or

C.L.R. x 2 = C.L.D

I.R. = INSIDE RADIUS: The radius of the inner most part of the bend.


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