According to the production method, seamless pipe is divided into hot-rolled pipe, cold-rolled pipe, cold-drawn pipe, extruded pipe, pipe jacking and so on. According to the cross-section shape, seamless steel pipe can be divided into two types: circular and irregular. The irregular pipe has many complex shapes, such as square, ellipse, triangle, hexagonal, melon seed, star and finned pipe. The maximum diameter is 650 mm and the minimum diameter is 0.3 mm. According to different uses, there are thick-walled and thin-walled tubes. 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.
Seamless pipe material can be divided into ordinary and high quality carbon structural steel (Q215A - Q275A and #10 - #50 steel), low alloy steel (09MnV, 16Mn, etc.), alloy steel, stainless acid-resistant steel, etc. According to their use, they are divided into two categories: general use (for water conveyance, gas pipeline and structural components, mechanical parts) and special use (for boilers, geological exploration, bearings, acid resistance, etc.).
Seamless steel tubes are widely used.
1, Seamless steel pipe for general use is rolled by common carbon structural steel, low alloy structural steel or alloy structural steel, with the largest output. It is mainly used as pipeline or structural parts for conveying fluids.
2, According to different uses, there are three types of supply:
a. supply according to chemical composition and mechanical properties;
b. supply according to mechanical properties;
c. supply according to hydraulic test.
For steel pipes supplied according to category a and b, if they are used to withstand liquid pressure, hydrostatic tests should also be carried out.
3. Seamless tubes for special purposes include seamless tubes for boilers, chemical and electric power, seamless tubes for geology and seamless tubes for petroleum, etc.