Elbow as a kind of pipe fitting, used to connet two pipes. As usual , elbow contains three material , it is carbon steel elbow, stainless steel elbow and alloy steel elbow. Elbow usually has seamless elbow and erw elbow. 1/2"-24" often is seamless elbow, size over 24",  it usually means erw elbow. We use hot forming elbow machine to produce carbon steel elbow, the production of carbon steel elbow is simple.