Analyze the national standard seamless steel pipe Analyze the national standard seamless steel pipe specification table

The national standard seamless steel pipe is made of steel ingots or solid tube billets through perforation into capillary tubes, and then made by hot rolling, cold rolling or cold drawing. National standard steel pipe has an important position in my country's steel pipe industry. According to incomplete statistics, there are more than 240 national-standard steel pipe manufacturers in my country, and more than 250 sets of seamless 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 for rolling the national standard steel pipe is a round tube billet. The round tube billet is cut by a cutting machine into a billet with a length of about 1 meter, 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 is out of the furnace, it must be 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 successively cross-rolled, continuous rolled or extruded by three rolls. 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 sizing, the national standard steel pipe 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.

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