The seamless steel tube is perforated from the entire round steel, and there is no welded steel pipe on the surface. According to the production method, seamless steel pipes can be divided into hot -rolled seamless steel pipes, cold -rolled seamless steel pipes, cold pulled seamless steel pipes, squeezing seamless steel pipes, and top pipes. According to the shape of the section, seamless steel tubes are divided into two types: round and alien. The alien pipes include square, oval, triangular, hexagonal, melon seeds, astrology, and wing tubes.