Seamless steel pipe is a steel pipe that is perforated from the entire round steel and has no welds on the surface, which is called seamless steel pipe. According to production methods, seamless steel pipes can be divided into hot-rolled seamless steel pipes, cold-rolled seamless steel pipes, cold-drawn seamless steel pipes, extruded seamless steel pipes, top pipes, etc. According to the cross-sectional shape, seamless steel pipes are divided into two types: circular and irregular. The irregular pipes have various complex shapes such as square, elliptical, triangular, hexagonal, melon seed, star, and finned pipes. The maximum diameter is 900mm, and the minimum diameter is 4mm. According to different purposes, there are thick walled seamless steel pipes and thin-walled seamless steel pipes. Seamless steel pipes are mainly used for petroleum geological drilling pipes, cracking pipes for petrochemical industry, boiler pipes, bearing pipes, and high-precision structural steel pipes for automobiles, tractors, and aviation.