China's implementation standards for seamless steel tubes:
 Seamless steel pipe for structure (GB/T8162-2008) is a seamless steel pipe used for general structure and mechanical structure.
 Seamless steel pipe for fluid transportation
(GB/T8163-2008) is a general seamless steel pipe used to transport water, oil, gas and other fluids.
 Seamless steel pipes for low and medium pressure boilers (GB3087-2008) are high-quality carbon structural steels used to manufacture superheated steam pipes, boiling water pipes for low and medium pressure boilers of various structures, and superheated steam pipes and arch brick pipes for locomotive boilers. Hot rolled and cold drawn (rolled) seamless steel tubes.
 Seamless steel pipes for high-pressure boilers (GB5310-2008) are high-quality carbon steel, alloy steel and stainless heat-resistant steel seamless steel pipes for the heating surface of water-tube boilers with high pressure and above.
 High-pressure seamless steel pipes for fertilizer equipment (GB6479-2000) are high-quality carbon structural steel and alloy steel seamless steel pipes suitable for chemical equipment and pipelines with working temperature of -40~400℃ and working pressure of 10~30Ma .
 Seamless steel pipes for petroleum cracking (GB9948-2006) are seamless steel pipes suitable for furnace tubes, heat exchangers and pipelines in petroleum refineries.
 Steel pipes for geological drilling (YB235-70) are steel pipes used for core drilling by geological departments. They can be divided into drill pipes, drill collars, core pipes, casing pipes
and sedimentation pipes according to their purposes.
 Seamless steel pipes for diamond core drilling (GB3423-82) are seamless steel pipes used for drill pipes, core rods, and casings for diamond core drilling.
 Petroleum drilling pipe (YB528-65) is a seamless steel pipe that is thickened inside or outside at both ends of oil drilling. Steel pipes are divided into two types: wire and non-wired. Wired pipes are connected by joints, and non-wired pipes are connected with tool joints by butt welding.
 Carbon steel seamless steel pipes for ships (GB5213-85) are carbon steel seamless steel pipes used in the manufacture of Class I pressure piping systems, Class II pressure piping systems, boilers and superheaters. The working temperature of the carbon steel seamless steel pipe wall does not exceed 450℃, and the working temperature of the alloy steel seamless steel pipe wall exceeds 450℃.
 Seamless steel pipes for automobile axle casings (GB3088-82) are high-quality carbon structural steel and alloy structural steel hot-rolled seamless steel pipes used in the manufacture of automobile axle casings and drive axle axle tubes.
 High-pressure oil pipes for diesel engines (GB3093-2002) are cold-drawn seamless steel pipes used to manufacture high-pressure pipes for diesel engine injection systems.
 Precision inner diameter seamless steel pipes for hydraulic and pneumatic cylinders (GB8713-88) are cold-drawn or cold-rolled precision seamless steel pipes with precise inner diameters for the manufacture of hydraulic and pneumatic cylinders.
 Cold-drawn or cold-rolled precision seamless steel pipe (GB3639-2000) is a cold-drawn or cold-rolled precision seamless steel pipe with high dimensional accuracy and good surface finish for mechanical structures and hydraulic equipment. Choosing precision seamless steel pipes to manufacture mechanical structures or hydraulic equipment can greatly save machining man-hours, improve material utilization, and at the same time help improve product quality.
 Stainless steel seamless steel pipe for structure (GB/T14975-2002) is a hot-rolled stainless steel made of corrosion-resistant pipes and structural parts and parts widely used in the chemical, petroleum, textile, medical, food, machinery and other industries (Extruded, expanded) and cold drawn (rolled) seamless steel tubes.
 Stainless steel seamless steel pipes for fluid transportation (GB/T14976-2002) are hot-rolled (extruded, expanded) and cold-drawn (rolled) seamless steel pipes made of stainless steel used to transport fluids.
 Special-shaped seamless steel pipe is a general term for seamless steel pipes with cross-sectional shapes other than round pipes. According to the different shape and size of the steel pipe section, it can be divided into equal-walled special-shaped seamless steel pipe (code D), unequal-walled special-shaped seamless steel pipe (code BD), and variable diameter special-shaped seamless steel pipe (code BJ). Special-shaped seamless steel pipes are widely used in various structural parts, tools and mechanical parts. Compared with round pipes, special-shaped pipes generally have larger moments of inertia and section modulus, and have greater bending and torsion resistance, which can greatly reduce structural weight and save steel.
 Seamless steel pipes for low-temperature pipelines (GB/T18984-2003) are suitable for -45℃～-195℃ low-temperature pressure vessel pipes and seamless steel pipes for low-temperature heat exchanger pipes.
Seamless steel pipes are made of steel ingots or solid tube billets through perforation into capillary tubes, and then made by hot rolling, cold rolling or cold drawing. The specifications of seamless steel pipes are expressed in millimeters of outer diameter * wall thickness.
Seamless steel tubes are divided into two types: hot-rolled and cold-rolled (dial) seamless steel tubes. Hot-rolled seamless steel pipes are divided into general steel pipes, low and medium pressure boiler steel pipes, high pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, geological steel pipes and other steel pipes. Cold rolled (dial) seamless steel pipes are divided into general steel pipes, low and medium pressure boiler steel pipes, high pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, and other steel pipes, as well as carbon thin-walled steel pipes, alloy thin-walled steel pipes, Stainless thin-walled steel pipes, special-shaped steel pipes. The outer diameter of hot-rolled seamless pipe is generally greater than 32mm and the wall thickness is 2.5-75mm. The outer diameter of cold-rolled seamless pipe can be up to 6mm and the wall thickness can be up to 0.25mm. The outer diameter of thin-walled pipe can be up to 5mm and the wall thickness is less than 0.25mm. Rolling has higher dimensional accuracy than hot rolling.
Generally, seamless steel pipes are made of 10#, 20#, 30#, 35#, 45# and other high-quality carbon steels such as 16Mn, 5MnV and other low-alloy structural steels or 40Cr, 30CrMnSi, 45Mn2, 40MnB and other composite steels that are hot-rolled or cold Rolled. 10#, 20# and other low-carbon steel seamless pipes are mainly used for fluid transportation pipelines. Seamless tubes made of medium carbon steel such as 45 and 40Cr are used to manufacture mechanical parts, such as stressed parts of automobiles and tractors. Generally, seamless steel pipes should be used for strength and flattening tests. Hot-rolled steel pipes are delivered in hot-rolled state or heat-treated state; cold-rolled steel pipes are delivered in heat-treated state.
The hot-rolled seamless steel pipe has a high temperature, a small deformation resistance, and a large amount of deformation. Taking the rolling of steel plate as an example, the thickness of the continuous casting billet is generally about 230mm, and after rough rolling and finishing rolling, the final thickness is 1-20mm. At the same time, due to the small width-to-thickness ratio of the steel plate, the dimensional accuracy requirements are relatively low, and the shape problem is not prone to occur, and the crown is mainly controlled. The requirements for the structure are generally achieved through controlled rolling and cooling, that is, controlling the opening temperature, final rolling temperature and coiling temperature of finishing rolling to control the microstructure and mechanical properties of the strip.
Tips: ASTM A53 covers seamless and welded steel pipe with nominal wall thickness. The surface condition is usually black and hot-dipped galvanized. ASTM A53 is produced mainly for pressure and mechanical applications, and is also used for transport of steam, water, gas line pipes.
ASTM A53 ERW steel pipe is a typical carbon steel pipe. It is largely used to convey fluids at low / medium pressures such as oil, gas, steam, water, air and also for mechanical applications.