The manufacturing processes for large - diameter thick - wall seamless steel pipes can be divided into three basic methods: cold drawing, cold rolling, and hot rolling. Pipes made of materials such as 10#, 20#, 35#, and 45# are called ordinary steel pipes. 16Mn, which is between ordinary steel pipes and alloy steel pipes, is called low - alloy steel pipe. Pipes made of materials like 27SiMn, 12CrMoV, 10CrMo910, 15CrMo, 35CrMo, and stainless steel pipes are collectively referred to as alloy steel pipes.
According to their uses, they can be classified into seamless steel pipes for structural use, seamless steel pipes for transportation, seamless steel pipes for boilers, high - pressure seamless steel pipes for boilers, high - pressure seamless steel pipes for fertilizer equipment, seamless steel pipes for geological exploration, seamless steel pipes for oil exploration, seamless steel pipes for petroleum cracking, seamless steel pipes for ships, cold - drawn and cold - rolled precision seamless steel pipes, and various alloy pipes.
Seamless steel pipes are expressed in terms of outer diameter and wall thickness. Thick - wall seamless steel pipes are mainly used in various applications such as machining, coal mines, hydraulic cylinders, etc.
Classification of thick - wall seamless steel pipes: hot - rolled thick - wall seamless steel pipes, cold - rolled thick - wall seamless steel pipes, cold - drawn thick - wall seamless steel pipes, extruded thick - wall seamless steel pipes, and pipe jacking.
Stainless steel seamless pipes for structural purposes (GB/T 14975 - 1994) are hot - rolled (extruded, expanded) and cold - drawn (rolled) seamless pipes made of stainless steel. They are widely used as corrosion - resistant pipelines, structural components and parts in industries such as chemical engineering, petroleum, light textile, medical treatment, food, and machinery.
Stainless steel seamless pipes for fluid transportation (GB/T 14976 - 1994) are hot - rolled (extruded, expanded) and cold - drawn (rolled) seamless pipes made of stainless steel and are used for transporting fluids.
Special - shaped seamless steel pipes are a general term for seamless steel pipes with cross - sectional shapes other than circular. According to differences in the cross - sectional shape and size of the pipes, they can be further divided into special - shaped seamless steel pipes with equal wall thickness (code - named D), special - shaped seamless steel pipes with unequal wall thickness (code - named BD), and special - shaped seamless steel pipes with variable diameter (code - named BJ). Special - shaped seamless steel pipes are widely used in various structural components, tools, and mechanical parts. Compared with circular pipes, special - shaped pipes generally have larger moment of inertia and section modulus, as well as greater bending and torsional resistance, which can significantly reduce the structural weight and save steel.
1.Seamless steel pipes for structural purposes (GB/T 8162 - 1999) are applicable to seamless steel pipes for general structures and mechanical structures.
2.Seamless steel pipes for fluid transportation (GB/T 8163 - 1999) are applicable to general seamless steel pipes for transporting fluids such as water, oil, and gas.
3.Seamless steel pipes for low - and medium - pressure boilers (GB/T 3087 - 1999) are high - quality carbon structural hot - rolled and cold - drawn (rolled) seamless steel pipes used for manufacturing superheated steam pipes, water - boiling pipes of various low - and medium - pressure boilers, as well as superheated steam pipes, large flue pipes, small flue pipes, and arch brick pipes for locomotive boilers.
4.Seamless steel pipes for high - pressure boilers (GB5310 - 1995) are seamless steel pipes made of high - quality carbon steel, alloy steel, and stainless heat - resistant steel, which are used to manufacture the heating surfaces of water - tube boilers with high - pressure and above.
5.High - pressure seamless steel pipes for fertilizer equipment (GB6479 - 2000) are seamless steel pipes made of high - quality carbon structural steel and alloy steel, suitable for chemical equipment and pipelines with a working temperature ranging from -40℃ to 400℃ and a working pressure from 10 to 30 MPa.
6.Seamless steel pipes for petroleum cracking (GB9948 - 88) are seamless steel pipes suitable for furnace tubes, heat exchangers and pipelines in petroleum refineries.
7.Steel pipes for geological drilling (YB235 - 70) are used by geological departments for core drilling. According to their uses, they can be divided into drill pipes, drill collars, core barrels, casings, and settling pipes, etc.
8.Seamless steel pipes for diamond core drilling (GB3423 - 82) are seamless steel pipes used for drill pipes, core rods and casings in diamond core drilling.
9.Oil drilling pipes (YB528 - 65) are seamless steel pipes with internal or external upsetting at both ends for oil drilling. The pipes are divided into two types: threaded pipes and non - threaded pipes. Threaded pipes are connected by pipe heads, while non - threaded pipes are connected to tool joints by butt - welding.
10.Carbon steel seamless steel pipes for ships (GB5213 - 85) are carbon steel seamless steel pipes used for manufacturing Class 1 and Class 2 pressure - resistant pipe systems of ships, as well as boilers and superheaters. For carbon steel seamless steel pipes, the working temperature of the pipe wall does not exceed 450°C, while for alloy steel seamless steel pipes, the working temperature of the pipe wall exceeds 450℃
11.Seamless steel pipes for automotive half - shaft sleeves (GB3088 - 82) are hot - rolled seamless steel pipes made of high - quality structural carbon steel and alloy structural steel, used for manufacturing automotive half - shaft sleeves and drive axle housing shafts.
