What is seamless pipe?

A seamless pipe is a long strip of steel with a hollow section and no seams around it. There are more than 5,100 production plants under more than 1,850 companies in more than 110 countries in the world that produce seamless pipes, of which there are more than 260 plants under more than 170 companies in 44 countries that produce oil pipes.

Its standards are mainly classified as follows:

1. Structural seamless pipes (GB/T8162-2008) are seamless pipes for general structures and mechanical structures.

2. Seamless pipe for fluid transportation (GB/T8163-2008) is a general seamless pipe used to transport water, oil, gas and other fluids.

3. Seamless pipes for low and medium pressure boilers (GB3087-2008) are used for the manufacture of superheated steam pipes, boiling water pipes, and superheated steam pipes, large smoke pipes, small smoke pipes and arch bricks for low and medium pressure boilers of various structures. Hot-rolled and cold-drawn (rolled) seamless pipes of high-quality carbon structural steel for pipes.

4. Seamless tubes for high-pressure boilers (GB5310-2008) are high-quality carbon steel, alloy steel and stainless heat-resistant steel seamless tubes used to manufacture the heating surface of water-tube boilers with high pressure and above.

5. High-pressure seamless pipe for fertilizer equipment (GB6479-2000) is a high-quality carbon structural steel and alloy steel seamless pipe suitable for chemical equipment and pipelines with a working temperature of -40~400℃ and a working pressure of 10~30Ma.

6. Seamless pipes for petroleum cracking (GB9948-2006) are seamless pipes for furnace tubes, heat exchangers and pipelines in petroleum refineries.

7. The steel pipe for geological drilling (YB235-70) is a steel pipe used by the geological department for core drilling. According to the purpose, it can be divided into drill pipe, drill collar, core pipe, casing and sedimentation pipe.

8. Seamless pipe for diamond core drilling (GB3423-82) is a seamless pipe for drill pipe, core pipe and casing for diamond core drilling.

9. Oil drilling pipe (YB528-65) is a seamless pipe used for inner or outer thickening at both ends of oil drilling.

10. Carbon steel seamless pipe for ships (GB5312-85)
China Classification Society Material and Welding Specifications - China Classification Society (CCS)
Det Norske Veritas (DNV) Rules - Det Norske Veritas (DNV)
Lloyd's Register of Shipping (LR) Specifications - Lloyd's Register of Shipping (LR)
Germanischer Lloyd (GL) Specification - Germanischer Lloyd (GL)
American Bureau of Shipping (ABS) Specifications - American Bureau of Shipping (ABS)
Bureau Veritas (BV) Specifications - Bureau Veritas (BV)
Italian classification society (RINA) specification - Italian classification society (RINA)
Nippon Kaisha (NK) Rules - Nippon Kaisha (NK)
It is a carbon steel seamless pipe for the manufacture of Class I pressure-resistant piping systems, Class II pressure-resistant piping systems, boilers and superheaters. The working temperature of the carbon steel seamless pipe wall does not exceed 450℃, and the working temperature of the alloy steel seamless pipe wall exceeds 450℃.

11. Seamless pipe for automobile axle casing (GB3088-82) is a high-quality carbon structural steel and alloy structural steel hot-rolled seamless pipe used for manufacturing automobile axle casing and drive axle axle casing.

12. High pressure oil pipe for diesel engine (GB3093-86) is a cold drawn seamless pipe for manufacturing high pressure pipe of diesel engine injection system.

13. Precision inner diameter seamless pipes for hydraulic and pneumatic cylinders (GB8713-88) are cold drawn or cold rolled precision seamless pipes with precise inner diameters for the manufacture of hydraulic and pneumatic cylinders.

14. Cold-drawn or cold-rolled precision seamless pipe (GB3639-83) is a cold-drawn or cold-rolled precision seamless pipe with high dimensional accuracy and good surface finish for mechanical structures and hydraulic equipment. Use precision seamless pipes to manufacture mechanical structures or hydraulic equipment.

15. Structural stainless steel seamless pipes (GB/T14975-2002) are hot-rolled ( Extrusion, expansion) and cold drawn (rolled) seamless pipes.

16. Stainless steel seamless pipes for fluid transportation (GB/T14976-2002) are hot-rolled (extruded, expanded) and cold-drawn (rolled) seamless pipes made of stainless steel for fluid transportation.

17. Special-shaped seamless pipe is a general term for seamless pipes with other cross-sectional shapes other than round pipes. According to the shape and size of the steel pipe section, it can be divided into equal-wall thickness special-shaped seamless pipe (code D), unequal wall thickness special-shaped seamless pipe (code BD), variable diameter special-shaped seamless pipe (code BJ). Shaped seamless pipes are widely used in various structural parts, tools and mechanical parts.

18. Seamless steel pipes for low temperature pipelines (GB/T18984-2003) are seamless steel pipes used for -45℃～-195℃ low temperature pressure vessel pipes and low temperature heat exchanger pipes.
Generally, seamless pipes are made of 10, 20, 30, 35, 45 and other high-quality carbon-structured steels such as 16Mn, 5MnV and other low-alloy structural steels or 40Cr, 30CrMnSi, 45Mn2, 40MnB and other combined steels by hot-rolling or cold-rolling. Seamless pipes made of low carbon steel such as 10 and 20 are mainly used for fluid transportation pipelines. 45, 40Cr and other medium carbon steel seamless pipes are used to manufacture mechanical parts, such as the stressed parts of automobiles and tractors.

Generally, seamless pipes are used to ensure strength and flattening tests. Hot-rolled steel pipes are delivered in a hot-rolled state or heat-treated state; cold-rolled steel pipes are delivered in a heat-treated state. Seamless pipes for low and medium pressure boilers: used to manufacture various low and medium pressure boilers, superheated steam pipes, boiling water pipes, water wall pipes and superheated steam pipes, large smoke pipes, small smoke pipes and arch brick pipes for locomotive boilers.
Hot-rolled or cold-rolled (dial) seamless tubes with high-quality carbon structural steel. It is mainly made of No. 10 and No. 20 steel. In addition to ensuring the chemical composition and mechanical properties, it is necessary to perform hydrostatic tests, curling, flaring, flattening and other tests. Hot-rolled delivery is in hot-rolled state, and cold-rolled (dial) is delivered in heat-treated state.

Calculation formula of seamless management theory:
(Outer diameter – wall thickness) × wall thickness × 0.02466 = weight per meter of seamless pipe {kg}