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, with a maximum diameter of 900mm and a minimum diameter of 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.

① Main production processes (main inspection processes) of hot-rolled seamless steel pipes:

Preparation and inspection of pipe blank → heating of pipe blank → perforation → rolling of pipe → reheating of steel pipe → sizing (reduction) → heat treatment → straightening of finished pipe → finishing → inspection (non-destructive, physical and chemical, bench inspection) → storage

② The main production processes of cold-rolled (drawn) seamless steel pipes are:

Preparation of raw materials → Acid washing and lubrication → Cold rolling (pulling) → Heat treatment → Straightening → Finishing → Inspection