Elbow, which is formed by stamping half-circular elbows from sheet metal of the same material as the pipe, and then welding the two halves together. Due to the different welding standards for various pipelines, it is usually shipped as semi-finished products with spot welding at the assembly points, and welding is performed on-site according to the pipeline weld grade. Therefore, it is also known as a two-piece welded elbow.