The steel tube has a hollow section, and its length is much larger than that of the steel with diameter or circumference.
They are divided into circular, square, rectangular and special-shaped steel tubes according to the section shape.
The material is divided into carbon structural steel pipe, low alloy structural steel pipe, alloy steel pipe and composite steel pipe.
It is divided into pipeline, engineering structure, thermal equipment, petrochemical industry, mechanical manufacturing, geological drilling, and high pressure equipment for use.

According to the production process, it is divided into seamless steel pipe and welded pipe, of which two kinds of seamless steel pipe are hot rolling and cold rolling (drawing). The welded pipe is divided into straight seam welded pipe and spiral seam welded pipe.

Steel pipe is not only used for transporting fluid and powdery solid, exchanging heat energy, manufacturing mechanical parts and containers, but also an economic steel. The use of steel pipe to build structural grid, pillar and mechanical support can reduce weight, save metal 20 to 40%, and realize mechanized construction in factories. The manufacture of road and bridge with steel pipe can not only save steel products and simplify construction, but also greatly reduce the area of protective coating and save investment and maintenance costs.

According to the production method, the steel pipe can be divided into two main categories: seamless steel pipe and slotted steel pipe.

1, seamless steel tubes can be divided into hot rolled seamless pipes, cold drawn tubes, precision steel pipes, hot expansion pipes, cold spinning pipes and extruded pipes according to the production methods.

Seamless steel tubes are made of high quality carbon steel or alloy steel, and are divided into hot rolling and cold rolling (drawing).

2, welded pipes are divided into furnace pipe, electric welding (resistance welding) tube and automatic arc welding pipe because of its different welding technology. Because of its different welding forms, there are two kinds of welded pipe and spiral welded pipe, and the end shape is divided into circular welded pipe and special type (square, flat, etc.) welded pipe.

The welded steel pipe is made of the rolled tube shaped steel plate, which is welded by the seam or spiral seam. In the manufacturing method, it is divided into the welded pipe of low pressure fluid transportation, the spiral seam welded pipe, the direct coil welding pipe, the welding pipe and so on. Seamless steel pipe can be used in various industries such as liquid pressure pipes and gas pipes. Welded pipes can be used for water conveyance pipelines, gas pipes, heating pipes, electrical appliances pipes, etc.