The classification method of the curvature radius classification welding elbow is divided into its long radius elbow and short radius elbow according to its radius of curvature. A long radius elbow refers to the outer diameter of the tube whose radius of curvature is equal to 1.5 times, ie R = 1.5 D. The short radius elbow means that its radius of curvature is equal to the outer diameter of the tube, ie R = D. In the formula, D is the diameter of the elbow and R is the radius of curvature. The most common one is the 1.5D elbow. If it is not indicated in the contract as 1D or 1.5D, then it is necessary to optimize the 1.5D. The most commonly used implementation standards in China are GB/T12459-2005, GB/13401-2005, GB/T10752-1995. The elbow is a metal pipe fitting that changes the direction of the pipeline on the carbon steel pipe. The connection method is threaded and welded. According to the angle, there are three most commonly used 45° and 90°180°, and other abnormal angle elbows such as 60° are also included according to engineering needs. Elbows are made of cast iron, stainless steel, alloy steel, malleable iron, carbon steel, non-ferrous metals and plastics. The way to connect to the pipe is: direct welding (the most common way) flange connection, hot melt connection, fused connection, threaded connection and socket connection. According to the production process, it can be divided into: welding elbow, punching elbow, push elbow, casting elbow, etc. Other names: 90 degree elbow, right angle bend, love and bend.
Carbon steel can be divided into: 10# 20# A3 Q235A 20g Q345B 20G 16Mn ASTM A234 ASTM A105 st37 ASTM A403, etc.