In a piping system, a bend is a pipe fitting that changes the direction of the line. According to the Angle, there are 45° and 90°180° three more commonly used, in addition, according to the needs of the project also includes 60° and other abnormal Angle elbow. Elbow materials are cast iron, stainless steel, alloy steel, malleable cast iron, carbon steel, non-ferrous metals and plastics. The connection modes with the pipe are: direct welding (the more commonly used way) flange connection, hot melt connection, electric melt connection, thread connection and socket connection. According to the production process can be divided into: welding elbow, stamping elbow, push elbow, casting elbow, butt welding elbow and so on. Other names: 90 degree bend, right Angle bend, love bend, etc.