Seamless steel pipe is a steel pipe made by perforating a whole round steel bar. There is no weld on the surface. It is called seamless steel pipe. According to the production method, seamless steel pipe can be divided into hot-rolled seamless steel pipe, cold-rolled seamless steel pipe, cold-drawn seamless steel pipe, extruded seamless steel pipe, jacking pipe, etc. According to the cross-sectional shape, seamless steel pipe is divided into round and special-shaped. Special-shaped pipes have square, oval, triangle, hexagon, melon seed, star, winged pipe and many other complex shapes. The maximum diameter is 900mm and the minimum diameter is 4mm. According to different uses, there are thick-walled seamless steel pipes and thin-walled seamless steel pipes. Seamless steel pipes are mainly used as petroleum geological drilling pipes, cracking pipes for petrochemicals, boiler pipes, bearing pipes, and high-precision structural steel pipes for automobiles, tractors, and aviation.

GB5310-1995 is the standard for seamless steel pipes used to manufacture the heating surface of water tube boilers with high pressure and above.

GB3093-1986 is the manufacturing standard for high-pressure oil pipes for diesel engines.

GB/T8162-1999 is the national standard for seamless steel pipes for general structures and mechanical structures.

YB235-70 is the standard model for geological drilling steel pipes, mainly used for core drilling in geological departments.

GB5213-85 is the standard for carbon steel seamless steel pipes for ships.

GB3423-82 is a seamless steel pipe specially used for diamond core drilling, mainly used to make drill rods, core rods and casings.

GB3087-1999 is the standard for seamless steel pipes for low and medium pressure boilers.

GB/T8163-1999 is the standard for seamless steel pipes for fluid transportation.

GB9948-88 is the standard for seamless steel pipes for petroleum cracking.

GB6479-2000 is the standard for high-pressure seamless steel pipes for fertilizer equipment.

GB/T14975-1994 is the standard for stainless steel seamless steel pipes for structures.

GB8713-88 is the standard for precision inner diameter seamless steel pipes for hydraulic and pneumatic cylinders.

GB/T14976-1994 is the standard for stainless steel seamless steel pipes for fluid transportation.

GB3088-82 is the standard for high-quality carbon structural steel and alloy structural steel hot-rolled seamless steel pipes used to manufacture automobile half-axle sleeves and drive axle axle housing shaft tubes.

GB/T8713-1988 is the standard for precision inner diameter seamless steel pipes for hydraulic and pneumatic cylinders.

GB13296-1991 is the standard for stainless steel seamless steel pipes for boilers and heat exchangers.

GB3639-83 is the standard for cold-drawn or cold-rolled precision seamless steel pipes.

GB/T3094-1986 is the standard for cold-drawn seamless steel pipes and special-shaped steel pipes.

GB/T17396-1998 is the standard for hot-rolled seamless steel pipes for hydraulic props.

GB/T3639-1983 is the standard for cold-drawn or cold-rolled precision seamless steel pipes.

1. Ordinary seamless steel pipe: The outer diameter is divided into 22mm, 25mm, 28mm, 32mm, 38mm, 42mm, 48mm, 57mm, 60mm, 73mm, 83mm, 90mm, 100mm and other specifications.

2. Hot-rolled seamless steel pipe: The outer diameter is 10-100mm and the wall thickness is 2-10mm.

3. High-pressure seamless steel pipe: It has high strength and durability and is widely used in high-pressure boilers, pipelines and other fields. The outer diameter range is 10-159mm and the wall thickness range is 2-45mm.

4. Precision seamless steel pipe: It has high precision and is suitable for high-precision machining and manufacturing. The outer diameter range is 10-377mm and the wall thickness range is 1-25mm.

5. Stainless steel pipe: It has good corrosion resistance and high strength and is widely used in chemical, food, medicine and other fields. The outer diameter range is 6-530mm and the wall thickness range is 0.5-15mm.

6. Rectangular tube: It has good compressive strength and durability, and is widely used in building structures and other fields. The specifications are 10×10-150×150mm.

7. Special-shaped tube: It has special shapes and structures, such as elliptical tubes, hexagonal tubes, etc., and is widely used in machinery manufacturing, decoration and other fields.

The materials include ordinary and high-quality carbon structural steel (Q215-A~Q275-A and 10~50 steel), low alloy steel (09MnV, 16Mn, etc.), alloy steel, stainless acid-resistant steel, etc.

Seamless steel pipes have a wide range of uses.

1. General-purpose seamless steel pipes are rolled from ordinary carbon structural steel, low-alloy structural steel or alloy structural steel, with the largest output, and are mainly used as pipes or structural parts for conveying fluids.

2. They are supplied in three categories according to different uses:

a. Supply according to chemical composition and mechanical properties;

b. Supply according to mechanical properties;

c. Supply according to water pressure test. Steel pipes supplied in categories a and b, if used to withstand liquid pressure, must also be subjected to water pressure tests.

3. Special-purpose seamless pipes include seamless pipes for boilers, chemical power, geological seamless steel pipes, and seamless pipes for petroleum.

Seamless steel pipes have hollow cross-sections and are widely used as pipelines for conveying fluids, such as pipelines for conveying oil, natural gas, coal gas, water, and certain solid materials. Compared with solid steels such as round steel, steel pipes are lighter in weight when the bending and torsional strengths are the same, and are an economical cross-section steel.

It is widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipes, automobile drive shafts, bicycle frames, and steel scaffolding used in construction. The use of steel pipes to manufacture annular parts can improve material utilization, simplify the manufacturing process, save materials and processing time, and has been widely used in steel pipe manufacturing.