Seamless steel pipe is a steel pipe made by piercing a whole round steel without any weld on the surface, which is called a seamless steel pipe. According to the production method, 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. Irregular pipes include square, elliptical, triangular, hexagonal, melon seed shaped, star shaped, and winged pipes with various complex shapes. 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 as drilling pipes for petroleum geology, cracking pipes for petrochemicals, boiler pipes, bearing pipes, as well as high-precision structural steel pipes for automobiles, tractors, and aviation.