The GB seamless steel pipe is made of steel ingot or solid tube blank through perforation, and then made by hot rolling, cold rolling or cold drawing. GB steel pipe has an important position in China’s steel pipe industry. According to incomplete statistics, there are more than 240 national standard steel pipe production enterprises and more than 250 seamless steel pipe units with an annual production capacity of more than 4.5 million tons. From the caliber, <φ76, accounting for 35%, <φ159-650, accounting 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 steel pipes, bearing pipes and automobile pipes are 50,000 yuan. Tons, accounting for 1.4%.seamless steel pipe manufacturer
The raw material for rolling the national standard steel pipe is a round tube blank, and the round tube embryo is cut into a blank having a length of about 1 m by a cutting machine, and sent to a furnace for heating via a conveyor belt. The billet is fed into a furnace and heated to a temperature of approximately 1200 degrees Celsius. The fuel is hydrogen or acetylene. Furnace temperature control is a key issue. After the round billet is released, it is subjected to a through-hole punching machine.
The more common perforating machine is a conical roller punching machine. This perforating machine has high production efficiency, good product quality, large diameter of perforation and can wear a variety of steel types. After perforation, the round billet is successively rolled, rolled or extruded by three rolls. After extrusion, the tube should be sizing. The sizing machine is rotated at a high speed by a conical drill bit into a steel core to form a steel pipe. The inner diameter of the steel pipe is determined by the outer diameter of the sizing machine drill bit.
After passing the sizing, the GB steel pipe enters the cooling tower and is cooled by water spray. After the steel pipe is cooled, it will be straightened. After the steel pipe is straightened, it is sent to a metal flaw detector (or water pressure test) by a conveyor belt for internal flaw detection. If there are cracks inside the steel pipe, bubbles and other problems will be detected. After the quality inspection of the steel pipe, it must be carefully selected by hand. After the quality inspection of the steel pipe, the paint is sprayed with the number, specification, production batch number, etc. It is hoisted into the warehouse by a crane.steel tubing manufacturers
The standard calculation formula for the bearing pressure of the national standard seamless steel pipe:
One: National standard seamless pipe outer diameter, specifications, wall thickness can withstand the pressure calculation method (the different tensile strength of different steel pipes) pressure = (wall thickness * 2 * steel material tensile strength) / (outer diameter * coefficient)
Two: It is known that the seamless pipe seamless steel pipe outer diameter and the pressure to calculate the wall thickness calculation method: wall thickness = (pressure * outer diameter * coefficient) / (2 * steel material tensile strength)
Three: seamless pipe pressure coefficient representation method: steel pipe pressure P <7Mpa coefficient S = 8 7 < steel pipe pressure P <17.5 coefficient S = 6 steel pipe pressure P> 17.5 coefficient S = 4
GB standard steel pipe implementation standards:
Seamless steel pipe for structure: GB8162-2008 2. Ground seam steel pipe for conveying fluid: GB8163-20083, seamless steel pipe for boiler: GB3087-2008 4. High-pressure seamless pipe for boiler: GB5310-2008 (ST45.8-III Type) 5. High-pressure seamless steel pipe for fertilizer equipment: GB6479-1999 6. Seamless steel pipe for geological drilling: YB235-70 7. Seamless steel pipe for oil drilling: YB528-65 8. Seamless steel pipe for petroleum cracking: GB9948- 88 9. Special seamless pipe for oil drill collar: YB691-70 10. Seamless steel pipe for automobile semi-axle: GB3088-1999 11. Seamless steel pipe for ship: GB5312-1999 12. Cold drawn cold-rolled precision seamless steel pipe: GB3639 -1999 13, various alloy tubes 16Mn, 27SiMn, 15CrMo, 35CrMo, 12CrMov, 20G, 40Cr, 12Cr1MoV, 15CrMo
In addition, there are GB/T17396-1998 (hot rolled seamless steel pipe for hydraulic props), GB3093-1986 (high pressure seamless steel pipe for diesel engine), GB/T3639-1983 (cold drawn or cold rolled precision seamless steel pipe), GB /T3094-1986 (cold drawn seamless steel pipe 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 -1994 (stainless steel seamless steel pipe for structure), GB/T14976-1994 (stainless steel seamless pipe for fluid transportation) GB/T5035-1993 (seamless steel pipe for automobile semi-axle casing), API SPEC5CT-1999 (casing and oil pipe) Specification) and so on.