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Seamless carbonsteel pipe is a capillary tube made of steel ingots or solid tube blanks through perforation, and then made by hot rolling, cold rolling or cold drawing. Seamless carbon steel pipes have an important position in my country’s steel pipe industry. According to incomplete statistics, there are more than 240 seamless carbon steel pipe production enterprises in my country, and more than 250 seamless carbon steel pipe units, with an annual production capacity of about 4.5 million tons. In terms of caliber, those with <φ76 accounted for 35%, and those with <φ159-650 accounted for 25%. In terms of varieties, general purpose pipes are 1.9 million tons, accounting for 54%; oil pipes are 760,000 tons, accounting for 5.7%; hydraulic props and precision pipes are 150,000 tons, accounting for 4.3%; stainless pipes, bearing pipes, and automotive pipes total 50,000 Tons, accounting for 1.4%.
The raw material of the seamless carbon steel pipe is a round tube blank, which is cut by a cutting machine into a blank of about 1 meter in length, and then sent to the furnace for heating via a conveyor belt. The billet is fed into the furnace and heated at a temperature of approximately 1200 degrees Celsius. The fuel is hydrogen or acetylene. The temperature control in the furnace is a key issue. After the round tube billet is out of the furnace, it is pierced through a pressure piercing machine. Generally, the more common piercing machine is the tapered roller piercing machine. This type of piercing machine has high production efficiency, good product quality, large perforation diameter expansion, and can wear a variety of steel types. After piercing, the round tube billet is cross-rolled, continuous rolled or extruded by three rolls one after another. After squeezing, take off the tube and calibrate. The sizing machine uses a tapered drill bit to rotate at a high speed into the steel blank to punch holes to form a steel pipe. The inner diameter of the steel pipe is determined by the length of the outer diameter of the drill bit of the sizing machine. After the steel pipe is sized, it enters the cooling tower and is cooled by spraying water. After the steel pipe is cooled, it will be straightened. After straightening, the steel pipe is sent to the metal flaw detector (or hydraulic test) by the conveyor belt for internal flaw detection. If there are cracks, bubbles, etc. inside the steel pipe, it will be detected. After the quality inspection of steel pipes, strict manual selection is required. After the quality inspection of the steel pipe, paint the serial number, specification, production batch number, etc. with paint. It is hoisted into the warehouse by a crane.
Seamless steel pipes are divided into hot-rolled (extruded) seamless steel pipes and cold-drawn (rolled) seamless steel pipes due to their different manufacturing processes. Cold drawn (rolled) tubes are divided into two types: round tubes and special-shaped tubes. Seamless steel pipes are divided into the following varieties due to their different uses:
1. Seamless steel pipe for structure (GBT8162-2008). Mainly used for general structure and mechanical structure. Its representative materials (brands): carbon steel, 20, 45 steel; alloy steel Q345, 20Cr, 40Cr, 20CrMo, 30-35CrMo, 42CrMo, etc.
2. Seamless steel pipe for conveying fluid (GBT8163-2008). Mainly used in engineering and large-scale equipment to transport fluid pipelines. The representative material (brand) is 20, Q345, etc.
3. Seamless steel pipes for low and medium pressure boilers (GB3087-2008) are used to manufacture superheated steam pipes, boiling water pipes for low and medium pressure boilers of various structures, and superheated steam pipes for locomotive boilers, large smoke pipes, small smoke pipes and arch bricks. High-quality carbon structural steel hot-rolled and cold-drawn (rolled) seamless steel pipes for pipes. Representative materials are 10 and 20 steel.
4. 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. Representative materials are 20G, 12Cr1MoVG, 15CrMoG, etc.
5. Seamless steel pipes for high-pressure fertilizer equipment (GB6479-2000) are high-quality carbon structural steel and alloy steel seamless steel pipes suitable for chemical equipment and pipelines with a working temperature of -40 to 400 ℃ and a working pressure of 10 to 30 Ma. Representative materials are 20, 16Mn, 12CrMo, 12Cr2Mo, etc.
6. Seamless steel pipes for petroleum cracking (GB9948-2006). Mainly used in boilers, heat exchangers and fluid pipelines of petroleum smelters. Its representative materials are 20, 12CrMo, 1Cr5Mo, 1Cr19Ni11Nb, etc.
7. 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.
8. Seamless steel pipes for diamond core drilling (GB3423-82) are seamless steel pipes for drill pipes, core rods, and casings used for diamond core drilling.
9. Petroleum drilling pipe (YB528-65) is a seamless steel pipe used for thickening inside or outside at both ends of oil drilling. There are two types of steel pipes: wire and non-wired. Wired pipes are connected by joints, and non-wired pipes are connected with tool joints by butt welding.
10. Carbon steel and carbon-manganese steel seamless steel pipes for ships (GB/5312-1999) 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℃. Representative materials are 360, 410, 460 steel grades, etc.
11. Seamless steel tubes for automobile axle sleeves (GB3088-82) are high-quality carbon structural steel and alloy structural steel hot-rolled seamless steel tubes for the manufacture of automobile axle sleeves and drive axle axle tubes.
12. High-pressure oil pipes for diesel engines (GB3093-86) are cold-drawn seamless steel pipes used in the manufacture of high-pressure pipes for diesel engine injection systems.
13. 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.
14. Cold-drawn or cold-rolled precision seamless steel pipe (GB3639-83) 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.
1 5. Structural stainless steel seamless steel pipe (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.
16. 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.
17. 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-thickness special-shaped seamless steel pipe (code D), unequal-thickness 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 machines.
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.
18. Seamless steel pipes for gas cylinders (GB18248-2000). Mainly used to make various gas and hydraulic cylinders. Its representative materials are 37Mn, 34Mn2V, 35CrMo, etc.
In addition, there are GB/T17396-1998 (hot-rolled seamless steel pipes for hydraulic props), GB3093-1986 (high-pressure seamless steel pipes for diesel engines), GB/T3639-1983 (cold drawn or cold-rolled precision seamless steel pipes), GB /T3094-1986 (cold drawn seamless steel pipe special-shaped steel pipe), GB/T8713-1988 (precision inner diameter seamless steel pipe for hydraulic and pneumatic cylinders), GB13296-1991 (stainless steel seamless steel pipe for boilers and heat exchangers), GB/T14975 -2002 (Stainless steel seamless steel pipe for structural use), GB/T14976-2002 (Stainless steel seamless steel pipe for fluid transportation), GB/T5035-1993 (Seamless steel pipe for automobile half-shaft casing), API SPEC5CT-1999 (casing and tubing) Specification) etc.

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