In the piping system, the piping is to change the direction of the elbow pipe. By angle points, 45 ° and 90 ° 180 ° three most commonly used, according to project needs in addition also includes other non-normal 60 ° angle bend. Elbow materials are cast iron, stainless steel, alloy steel, malleable iron, steel, nonferrous metals and plastics. Way connected with the pipe are: direct welding (the most common way) flange connection, hot melt connection, fused connection, threaded connections and socket type connections. According to the production process can be divided into: welding elbow, pressing elbow, push the system elbow, casting elbow. Other names: 90 degree elbow, right angle bend, bend, etc. love.