Elbows are a kind of pipe fitting used to change the pipeline direction. According to the different angles, there are elbows with angles of 45¡ã, 90¡ãand 180¡ã. And besides these three most commonly used elbows, according to the need of the project, there are also elbows with 60¡ãangles and other abnormal angle. The elbows have good comprehensive properties, so it is widely used in chemical industry, construction, water supply, drainage, oil industry, heavy industry, refrigeration, sanitation, plumbing, fire protection, electric power, aerospace, shipbuilding and other infrastructure projects.

As for the manufacture technology of elbows, the most important is to control the radius of curvature. For example, if the length of radius is 1.5D, then the radius of curvature must be within the tolerance range required. Because most of these fittings used for welding, in order to improve the welding quality, the end is always made into a groove, keeping a certain angle and certain boundary. This requirement is more stringent, the edge thickness, angle size and scope of deviation are defined, which makes elbows have more items in the geometric size than pipes. The surface quality and mechanical properties of elbows is basically the same to the pipes be connected.