Steel pipe is a kind of steel with hollow section and its length is much larger than the diameter or circumference.
According to the section shape, it is divided into circular, square, rectangular and special-shaped steel pipes;
According to the material, it is divided into carbon structural steel pipe, low alloy structural steel pipe, alloy steel pipe and composite steel pipe;
According to the purpose, it is divided into steel pipes for transmission pipeline, engineering structure, thermal equipment, petrochemical industry, machinery manufacturing, geological drilling, high-pressure equipment, etc;
According to the production process, it is divided into seamless steel pipe and welded steel pipe.