Common carbon steel pipe knowledge

Carbon steel pipes are made of steel ingots or solid round steel through perforation into capillary tubes, and then made by hot rolling, cold rolling or cold drawing. Carbon steel pipe plays an important role in my country's steel pipe industry.

Classification of carbon steel pipes

Carbon steel pipes are divided into two types: hot-rolled and cold-rolled (drawn) steel pipes.
Hot-rolled carbon 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.

In addition to 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, cold-rolled (dial) carbon steel pipes also include carbon thin-walled steel pipes, alloy thin-walled steel pipes, Rust 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 steel pipe can reach 6mm, and the wall thickness can reach 0.25mm. The outer diameter of thin-walled pipe can reach 5mm, and the wall thickness is less than 0.25mm. Cold rolling has higher dimensional accuracy than hot rolling.

General carbon steel pipe: It is made of high-quality carbon steel such as 10, 20, 30, 35, 45, 16Mn, 5MnV and other low-alloy structural steels or 40Cr, 30CrMnSi, 45Mn2, 40MnB and other alloy steels that are hot-rolled or cold-rolled. 10, 20 and other low carbon steel seamless pipes are mainly used for fluid conveying 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, carbon steel pipes are used to ensure strength and flattening tests. Hot-rolled steel pipes are delivered in a hot-rolled or heat-treated state; cold-rolled steel pipes are delivered in a heat-treated state.

Preparation method of carbon steel pipe

The raw material for carbon steel pipe is round tube billet, and the round tube embryo should be cut by cutting machine to grow billets with a length of about 1 meter, and transported to the furnace by conveyor belt. Billet is fed into the furnace to heat, the temperature is about 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 piercer. Generally, the more common piercer is the cone roll piercer. This kind of piercer 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 extrusion, the tube should be taken off for sizing. Sizing by high-speed rotary cone drill holes into the billet to form a tube. 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 and other problems inside the steel pipe, they 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. And hoisted into the warehouse by a crane.

Technical parameters of carbon steel pipe

Carbon steel pipes are made of steel ingots or solid tube blanks that are perforated into capillary tubes, and then made by hot rolling, cold rolling or cold drawing. Carbon steel pipe plays an important role in my country's steel pipe industry. According to incomplete statistics, there are more than 240 carbon steel pipe production enterprises in my country, more than 250 sets of carbon steel pipe units, and an annual production capacity of about 4.5 million tons. From the perspective of caliber, <φ76 accounts for 35%, and <φ159-650 accounts for 25%. In terms of varieties, general-purpose pipes are 1.9 million tons, accounting for 54%; petroleum steel pipes are 760,000 tons, accounting for 5.7%; hydraulic props and precision pipes are 150,000 tons, accounting for 4.3%. Accounted for 1.4%.
Specifications: The specifications of carbon steel pipes are expressed in millimeters of outer diameter * wall thickness.

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