Here in the pipeline system, elbow is to change the direction of the line pipe fittings ,Points according to the Angle 45 ° and 90 ° 180 ° three most commonly used, according to the requirements of the project also includes 60 °, and other abnormal Angle bend. Elbow materials have cast iron, stainless steel, alloy steel, malleable cast iron, carbon steel, nonferrous metal and plastic, etc. With the pipe connection mode: direct welding (way) of the most commonly used flange connection, hot melt connection, fused connection, threaded connection and socket type connection, etc. According to the production process can be divided into: welding bend, stamping elbow, pushing system bend, casting bend, butt welding elbow and so on. Other names: 90 degrees bend, right-angle bend, such as love and curved.