It is made of steel, hot pressing or forging elbow, and its connection form is to weld elbow and steel pipe directly. Elbow divided according to its radius of curvature, can be divided into long radius elbow and short radius elbow; divided by the pressure level to about seventeen, and the American Standard pipe is the same, which is the most commonly used STD and XS two; according to the angle of bend points, there are 45 degrees of butt welding elbow, elbow elbow 90 degrees and 180 degrees elbow and other different angles; divided by material: carbon steel, alloy steel and stainless steel