Seamless steel pipe is a long strip of steel with a hollow cross-section and no seams around its perimeter. Due to its hollow cross-section, steel pipes are widely used as pipelines for transporting fluids, such as oil, natural gas, coal gas, water, and certain solid materials. Compared to solid steel materials such as round bars, steel pipes are lighter in weight while maintaining the same bending and torsional strength. They are an economical cross-section steel material, widely used in the manufacture of structural components and mechanical parts, such as oil drill pipes, automobile drive shafts, bicycle frames, and steel scaffolding used in construction. Using steel pipes to manufacture circular parts can improve material utilization, simplify manufacturing processes, and save materials and processing time. For example, rolling bearing rings and jack sleeves are widely manufactured using steel pipes. Steel pipes are also indispensable materials for various conventional weapons, such as gun barrels, which require steel pipes for manufacturing. Steel pipes can be divided into round pipes and shaped pipes based on the shape of their cross-sectional area. Since the circular area is the largest under the condition of equal perimeter, round pipes can transport more fluids. In addition, the circular cross-section is more evenly stressed when subjected to internal or external radial pressure. Therefore, the vast majority of steel pipes are round pipes. However, round pipes also have certain limitations. For example, under the condition of plane bending, round pipes are not as strong as square or rectangular pipes in terms of bending strength. Some agricultural machinery skeletons and steel-wood furniture commonly use square or rectangular pipes. Depending on different applications, other shaped steel pipes with different cross-sectional shapes are also required.

1. Structural seamless steel tubes (GB/T8162-1999) are seamless steel tubes used for general structures and mechanical structures.

2. Seamless steel pipes for fluid conveyance (GB/T8163-1999) are general seamless steel pipes used for conveying fluids such as water, oil, and gas.

3. Seamless steel tubes for low and medium pressure boilers (GB3087-1999) are high-quality carbon structural steel hot-rolled and cold-drawn (rolled) seamless steel tubes used for manufacturing various structural low and medium pressure boiler superheated steam tubes, boiling water tubes, as well as superheated steam tubes, large smoke tubes, small smoke tubes, and arch brick tubes for locomotive boilers.

4. Seamless steel tubes for high-pressure boilers (GB5310-1995) are excellent carbon steel, alloy steel, and stainless heat-resistant steel seamless tubes used for the heating surfaces of water tube boilers with high pressure and above.

5. High-pressure seamless steel pipes for fertilizer equipment (GB6479-86) are excellent seamless steel pipes made of carbon structural steel and alloy steel, suitable for chemical equipment and pipelines with operating temperatures ranging from -40 to 400℃ and operating pressures ranging from 10 to 30MPa.

6. Seamless steel tubes for petroleum cracking (GB9948-88) are suitable for use as furnace tubes, heat exchangers, and pipelines in petroleum refineries.

7. Steel pipes for geological drilling (YB235-70) are steel pipes used by geological departments for core drilling. According to their purposes, they can be divided into drill pipes, drill collars, core barrels, casing pipes, and sedimentation pipes.

8. Seamless steel tubes for diamond core drilling (GB3423-82) are seamless steel tubes used for drill rods, core rods, and casings in diamond core drilling.

9. Oil drilling pipes (YB528-65) are seamless steel pipes used for oil drilling, with internal or external thickening at both ends. These steel pipes are divided into two types: threaded and non-threaded. Threaded pipes are connected using joints, while non-threaded pipes are connected to tool joints through butt welding.

10. Carbon steel seamless steel tubes for ships (GB5213-85) are used for manufacturing Class I pressure piping systems, Class II pressure piping systems, boilers, and superheaters for ships. The working temperature of the carbon steel seamless steel tube wall does not exceed 450℃, while the working temperature of the alloy steel seamless steel tube wall exceeds 450℃.

11. Seamless steel tubes for automotive half-shaft casings (GB3088-82) are high-quality hot-rolled seamless steel tubes made of carbon structural steel and alloy structural steel, which are used for manufacturing automotive half-shaft casings and drive axle housing shaft tubes.

12. High-pressure fuel pipes for diesel engines (GB3093-86) are cold-drawn seamless steel pipes used for manufacturing high-pressure pipes in diesel engine injection systems.