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　　Seamless carbon steel pipe is made of steel ingot or solid billet by piercing and then hot rolling, cold rolling or cold drawing. Seamless carbon steel pipe plays an important role in China's steel pipe industry. According to incomplete statistics, there are more than 240 seamless carbon steel pipe manufacturers in China, more than 250 ASTM A53 Seamless Carbon Steel Pipe units, with an annual capacity of more than 4.5 million tons. In terms of caliber, < φ 76 accounts for 35%, and < φ 159-650 accounts for 25%. In terms of varieties, 1.9 million tons of general-purpose pipes, accounting for 54%; 760000 tons of oil pipes, accounting for 5.7%; 150000 tons of hydraulic props and precision pipes, accounting for 4.3%; 50000 tons of stainless pipes, bearing pipes and automobile pipes, accounting for 1.4%.

　　The raw material of seamless carbon steel pipe is round pipe blank. The round tube blank needs to be cut by the cutting machine to process the blank with a growth of about 1 meter, and sent to the furnace for heating through the conveyor belt. The billet is heated in a furnace at a temperature of about 1200 degrees Celsius. The fuel is hydrogen or acetylene. The temperature control in the furnace is a key problem. After the round tube blank is discharged, it needs to pass through the pressure piercer. The common piercer is the cone roll piercer. This kind of piercer has high production efficiency, good product quality, large perforation expanding capacity and can wear many kinds of steel.

　　After piercing, the round tube blank is successively rolled, continuously rolled or extruded by three rollers. After extrusion, the tube shall be removed for sizing. The sizing machine uses a cone-shaped bit to rotate into the steel embryo at high speed to drill holes to form steel pipes. The inner diameter of the steel pipe is determined by the outer diameter length of the drill bit of the sizing machine. After sizing, the steel pipe will enter the cooling tower and be cooled by water spray. After cooling, the steel pipe will be straightened. After straightening, the steel pipe is sent to the metal flaw detector by the conveyor belt for internal flaw detection. If there are cracks, bubbles and other problems inside the steel pipe, they will be detected. After the quality inspection of steel pipes, strict manual selection is also required. After steel pipe quality inspection, paint the number, specification, production batch number, etc. And it is hoisted into the warehouse by crane.

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