Carbon steel pipe can be divided into two categories: hot and cold rolled (pull) steel.
Hot-rolled carbon steel tube is divided into general, low, medium pressure boiler pipe, high pressure boiler pipe, steel pipe, stainless steel pipe, oil cracking pipe, geological steel pipes and other steel pipe.
General steel pipe: is hot-rolled or cold-rolled steel with 10,20,30,35,45 and other high quality carbon steel, 16Mn, 5MnV low-alloy structural steel or 40Cr, 30CrMnSi, 45Mn2,40MnB other alloy. 10, 20 and other low-carbon steel seamless pipes are mainly used for fluid pipes. The seamless tube made of medium carbon steel of 45,40Cr etc., used to fabricate mechanical parts, such as the force components of as cars, tractors. Usually carbon steel pipe is ought to ensure the strength and flattening test. Hot-rolled steel is in hot-rolled state or with heat treatment to deliver; Cold-rolled steel with heat treatment to deliver.
Cold-rolled (allocated) not only comprises general carbon steel pipe steel pipe, low pressure boiler pipe, high pressure boiler pipe, steel pipe, stainless steel pipe, oil cracking pipe and other steel pipes, but also includes carbon thin-walled steel, alloy thin-walled steel, stainless thin-walled stainless steel pipe, special- shaped steel. The diameter of hot-rolled seamless pipe is generally greater than 32mm, wall thickness 2.5-75mm. The diameter of cold-rolled seamless steel pipe can go to 6mm, wall thickness can be 0.25mm, outer diameter thin-walled tube to 5mm, wall thickness less than 0.25mm. The dimensional accuracy of cold-rolled is higher than that of hot-rolled.
The raw material of carbon steel pipe is round pipe billet. Round billet be?processed?into a length of about 1 meter blank by a cutting machine. And it should be delivered to the furnace by conveyor belt to heat. The billet is fed into the furnace to be heated with a temperature of about 1200 degrees Celsius. The fuel is hydrogen or acetylene. Furnace temperature control is the key issue. After a round tube came out, then, go through the pressure punching machine to perforate. Generally, more common puncher is tapered roller punching machine. This kind of punching machine has high production efficiency, product quality, perforated expanding capacity, can perforate a variety of steels. After perforation, round tube billet has been skew?rolled, continuous rolled or extruded. After extrusion, to conduct detached sizing. Sizing machine through high-speed rotary by cone drills bit after the perforated steel billet to form steel. Pipe inner diameter is determined by the drill length of outer diameter sizing mill. After sizing, steel pipe should be taken into the cooling tower through spray cooling pipe. After cooling, steel pipe will be straightened. After straightening the steel pipe, it will go to conveyor belt to the metal detection machine (or pressure test) for internal testing. If cracks, bubbles and other issues exist in the internal pipe, they will be detected. After quality control, it should pass the strict manual selection. If the steel pipe pass the quality inspection, using spray paint label number, size, production batch number. And send it into the warehouse by a crane.
According to incomplete statistics, China's current steel pipe production enterprises are about 240, carbon steel pipe mills are about 250 sets, with an annual capacity of about 450 million tons. From the perspective of caliber, <φ76, accounting for 35%, <φ159-650, accounting for 25%. From the perspective of species, the general purpose pipe is 1.9 million tons, accounting for 54%; oil pipe is 760,000 tons, accounting for 5.7%; hydraulic prop and precision pipe are both 15 million tons, accounting for 4.3% of stainless steel tube bearing tube, pipe applied in automobile has a total of 50,000 tons, accounting for 1.4%.