Seamless steel tube is a steel pipe made by piercing a whole round steel without any weld on the surface, which is called a seamless steel tube. According to the production method, seamless steel tubes can be divided into hot-rolled seamless steel tubes, cold-rolled seamless steel tubes, cold drawn seamless steel tubes, extruded seamless steel tubes, top pipes, etc. According to the cross-sectional shape, seamless steel tubes 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 tubes and thin-walled seamless steel tubes. Seamless steel tubes are mainly used as drilling pipes for petroleum geology, cracking pipes for petrochemicals, boiler pipes, bearing tubes, as well as high-precision structural steel tubes 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