Steel Pipes and Tubes refer to steel products that are open at both ends and have a hollow section, the ratio of its length to the perimeter is large. According to the production method, it can be divided into seamless steel pipe and welded steel pipes. The specifications of the steel pipe are expressed by the external dimensions (such as outer diameter or side length) and wall thickness, and its size ranges from a small capillary tube to a large diameter tube with a diameter of several meters. Steel pipes can be used in pipelines, thermal equipment, machinery industry, petroleum geological exploration, containers, chemical industry and special purposes.