Elbow plays a very important role in the pressure pipeline system. It can not only change the direction of the pipeline in the pipeline system, but also increase the flexibility of the pipeline, reduce the vibration of the pipeline, reduce the binding force of the pipeline, and play a certain role in compensating the thermal expansion. Therefore, elbow is a very important part of the pressure pipeline. The elbow is located in the most stressed part of the pipeline, so it is also the most vulnerable part of the pipeline. Elbow plays a role in changing the direction of the pipeline.

According to the angle division, there are 45 degree elbow, 90 degree elbow and so on. There are some elbow with unusual angle, such as 60 degree elbow. Because of the different needs of pipeline, the angle of elbow is also different.

According to the material classification, there are stainless steel, alloy steel, carbon steel and so on. According to the way of pipe connection, there are direct welding, flange connection, hot melt connection, electric fusion connection, thread connection and socket connection.

According to the production process, there are welding elbow, stamping elbow, push elbow, etc.

According to the radius of curvature, there are long radius elbow and short radius elbow (long radius elbow refers to its curvature radius equal to 1.5 times of the outer diameter of the pipe; short radius elbow refers to its radius of curvature equal to the outer diameter of the pipe.

According to different shapes and uses, there are ferrule elbow, double bearing elbow, flange elbow, reducing elbow, stamping elbow, push elbow, socket elbow, butt welding elbow, etc.

Elbow is a kind of pipe fitting which is suitable for pipe turning. It can be divided into seamless elbow and straight seam elbow according to different welding methods. Among all the pipe fittings used in the pipeline system, seamless elbow accounts for the largest proportion. Generally, different forming processes are selected for elbows with different materials or wall thickness. At present, the commonly used forming process of seamless elbow is hot pushing, stamping, extrusion, etc.

Because of its good comprehensive performance, elbow is widely used in chemical engineering, construction, drainage, petroleum, light and light industry, water heating, fire protection, electric power, aerospace, shipbuilding and other basic projects.