Seamless steel pipe is perforated by the whole round steel, the surface of the steel pipe without weld, called seamless steel pipe. According to the production method, seamless steel tube can be divided into hot rolled seamless steel tube, cold rolled seamless steel tube, cold drawn seamless steel tube, extruded seamless steel tube, pipe jacking, etc. According to the shape of section, seamless steel tube is divided into round and special-shaped, special-shaped tube has square, oval, triangle, hexagonal, melon seed, star, winged tube and a variety of complex shapes. The maximum diameter is 900mm and the minimum diameter is 4mm. According to different uses, there are thick wall seamless steel pipe and thin wall seamless steel pipe. Seamless steel pipe is mainly used as petroleum geology drilling pipe, petrochemical cracking pipe, boiler pipe, bearing pipe and automobile, tractor, aviation high-precision structural steel pipe.