Steel pipe bend is a bending pipe that used to change the pipeline direction. It is similar to pipe elbow, but differently pipe bend is longer than elbow and usually manufactured for the specific needs.
So depends on different bending radius (R) to distinguish bend and elbow.
In case bending radius is more than 2 times of D (diameter), it is pipe bend.
In case bending radius in 1D or 2D, it is elbow. (short radius elbow and long radius elbow).
Pipe Bending Radius: 3D, 5D, 6D, 8D and customized
Bending Degrees: 15°, 22.5°, 30°, 45°, 60°, 90°, 180° and customized
Steel pipe bending usually required in large diameter in oil and gas pipelines, since it has better capacity to transport the material, and long pipelines will need different radius of pipe bends to be intalled in complex conditions.
Large Diameter Steel Pipe Bend in API 5L X80 with Internal and External Coating
External coated PE.
Large Pipe Bending after Sand Blasting and Before Coating
Internal coated FBE.
The pipe bend is bent by a set of bending equipment with two processes: Cold simmering and hot pushing. (Including bending, squeezing, pressing, forging, machining and etc)
Insert the straight pipe into pipe bending machine, heat the pipe and use lever (installed with different dimension of mould) to bend the pipe.
Pipe bend and elbow both for change the pipe direction, still there are a lot of differences in below aspects:
As we talked above,
Steel pipe bend radius: Above 2 times of D, so there are 2D, 2.5D, 3D, 5D, 6D, 7D or 8D pipe bend.
Steel pipe elbow radius: R=1D or R=1.5D or 2D. Below 1.5D is short radius elbow, and more than 1.5D but not over 2D is long radius elbow.
R is radius of curvature; D is (elbow or bend) pipe diameter.
As above picture CLR could be in 1D, 1.5D, 2D, 3D, 5D etc.
Bend: Could be bend directly from a finished pipe with cold bending processes, to different degrees.
Elbow: Shall be made according by standard manufacture procedures, with hot finishing or hot bending, to a certain degree, 45°, 90° or 180°.
So by the help of simple production process with standard 1.5D or 1D, steel pipe elbow cost is lower than bend. Pipe bend is mostly required with customized radius or degrees so the processes is more complicated than elbow and cost is higher.
Bend: Compatible with slower liquid and lower pressure.
Elbow: Compatible with high pressure and rapid liquid.
Sometimes elbows must be used in narrow sections, because the radius of curvature of the elbow is small, generally 2D, but the pipe bend could be up to 40D.
Manufacturing standard: AISI B16.49
Material: Carbon steel, Alloy steel, Stainless steel
Material standards: API 5L Grade B, X42, X46, X52, X56, X60, X65, X70, X80 PSL1 & PSL2 & SOUR; ASTM A234 WPB, WPC, WP1, WP5, WP9, WP11, WP22, WP91; ASTM A403 304/304L, 316/316L.
Outer Diameters: 1/2'' to 60''. DN15 to DN1500
Radius range: R=2D, 2.5D, 3D, 5D, 6D, 8D
Degree range: 45 degree, 60 degree, 90 degree and customized.
Wall thickness: SCH 10, SCH 40, SCH80
Coatings: Black paint, galvanized, epoxy coated, 3PE, FBE