There are more classification ways of seamless steel pipes, and the common classification and specific application fields are as follows:

Classification by production mode  :

- Hot rolled (extruded) seamless steel pipe  : Generally rolled by ordinary carbon structural steel, low alloy structural steel or alloy structural steel, with a large output, mainly used as a pipeline or structural parts for transporting fluids. For example, it can be used to transport oil, natural gas, gas, water and some solid materials; It is also widely used in the manufacture of structural and mechanical parts, such as oil drill pipe, automobile drive shaft, bicycle frame and steel scaffolding in construction.

- Cold rolled (drawing) seamless steel pipe  : After cold rolling (drawing) process, with high dimensional accuracy and surface quality.

- Cold-drawn seamless steel pipe  : It has the characteristics of high dimensional accuracy and good surface finish, and is often used in occasions with high requirements for size and surface quality.

- Extruded seamless steel pipe  : can produce a more complex shape of seamless steel pipe.

- Pipe jacking  : Suitable for specific engineering requirements.

Classification by section shape :

- Circular section pipe  : under the condition of equal circumference, the circle area is the largest, more fluid can be transported, and the ring section is more uniform when it is subjected to internal or external radial pressure, and it is widely used.

- Shaped section pipe  : such as square pipe, rectangular pipe, oval pipe, semicircle pipe, triangular pipe, hexagonal pipe, convex pipe, quince-shaped pipe, etc. Under the condition of plane bending, the bending strength of the shaped section pipe may be greater than that of the circular pipe, and some agricultural machinery skeletons, steel and wood furniture often use square and rectangular pipes.

By material  :

- Carbon steel pipe  : made of carbon steel, such as common 10#, 20#, 45# steel. Widely used in the general structure and mechanical manufacturing field.

- Alloy steel pipe  : contains a certain amount of alloying elements, has good comprehensive performance, can be used for some of the strength, wear resistance, corrosion resistance and other requirements of high occasions.

- Stainless steel pipe  : has good corrosion resistance, often used in chemical, petroleum, food and other industries with high corrosion requirements.

- Composite pipe  : composed of two or more different materials, with the advantages of various materials, suitable for special working conditions.

 By use  :

- High pressure seamless tube for boiler  : Generally used 15CrMo, 12CrMoV and other materials rolling, for high temperature and high pressure environment in boiler equipment.

- Fluid pipe  : A large number of pipelines used to transport various fluids, such as oil, natural gas, gas, water and so on. Commonly used materials are 10#, 20#, 16Mn (Q345A, B, C, D, E) and so on.

- General structure pipe  : suitable for general structure, engineering support, mechanical processing, etc., material including 10#, 20#, 45#, 27SiMn, 16Mn (Q345A, B, C, D, E) and so on.

- Oil casing  : such as J55, K55, N80, L80, C90, C95, P110 and other materials, used in oil Wells to extract oil or gas, casing is used as the wall of oil and gas Wells.

- High pressure seamless pipe for fertilizer  : Made of 20, 15MnV, 12MnMoV, 10MoVNbTi, Cr17Mn18Mo2N and other materials, for high pressure equipment and pipelines in fertilizer production.

- Seamless pipe for geological and oil drilling : The use of special steel rolling for geological drilling, with the "DZ" symbol and two digits representing the steel yield point, for geological and oil drilling fields.

- Seamless pipes for chemical power  : In the chemical and power industry, used for conveying various media or as parts of specific equipment.

- Other special seamless pipe  : such as seamless steel pipe for ships, automobiles, aerospace, energy, geology, construction and military and other fields, according to different working conditions and requirements, choose the corresponding material and specifications.

Seamless steel pipe has a hollow section, compared with solid steel such as round steel, the bending and torsional strength is the same, the weight is light, is an economic section of steel. Its specific classification and application will vary according to different industry needs and engineering requirements. In the actual selection, it is necessary to consider the material, size, performance, use environment and other factors.