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Pipe Bending
Pipe Bending

In profile pipe and tube bending terminology, elbow types are often referred to and referenced by their respective elbow radii.

Custom pipe bends are usually any type of profile pipe bend that does not meet standard short or long radius bends at 45, 90, and 180 degree standard bends.

Custom profile pipe bends are not anything with standard 1D to 5D centerline bend radii with standard bends. Learn why you need to discuss the process used to make these bends—mandrel pipe bends or rotational stretch bends. Rotary stretch bending machines require a complete set of molds to successfully bend in the standard 1D to 5D range. This includes forward clamps, bending dies, mandrels, wiper dies, and push-assist dies. This set of tools is dedicated to specific pipe diameters and specific centerline radii. Designating these 1D to 5D bends as standard bends allows engineers to specify radii across a variety of pipe diameters while still being able to obtain parts at a reasonable cost in a reasonable amount of time.

Bends of 1.5D and above are considered long radius bends. A 2D bend on a 6-inch pipe will have a 12-inch centerline radius. This will be called a long radius bend, and it includes 2D to 5D bends (including 5D bends), or the centerline radius is 5 times the respective diameter of the pipe. The standard rotations of these standard bending specifications all roll on a single plane with a simple horizontal plane geometry.

For standard pipe bending, this can be done by comparing the bending radius with the diameter of the pipe to be bent. 1D, 2D, and 3D bends are commonly referred to as short-radius bends and long-radius bends; according to the 1D, 2D, and 3D specifications, the centerline radius of the bend is referred to as the multiplier for the corresponding diameter of the pipe. 1D is the centerline bending radius, which is twice the diameter of the pipe. This means that a 1D bend on a 6-inch pipe will be a 6-inch centerline radius. Short radius bends are designated as one-dimensional bends.

You can specify custom pipe bends on any radius, and it is more complicated because some parts require multiple bends in a single part. This is often called a spool. A spool is a length of prefabricated pipe. The number of bends is fixed in a certain length of pipe, the geometry of the bend is determined, and the pipe flange is fixed at both ends, so that it is ready to be bolted in place during installation. The spool can contain as many elbows as the part manufacturer / manufacturer allows or can accommodate. Many times, these types of custom pipe bends are called 3D bends because the plane of the bend changes as the bend changes, requiring forward and reverse rotation between bends