Seamless steel pipe is a kind of hollow cross section, no seams around the circle, square, rectangular steel. 
 Seamless steel ingot is made of perforated or solid through the capillary tube, and then by the hot-rolled, cold-rolled or cold call is made. Specifications of seamless steel tubes with wall thickness mm diameter * number indicates. Hot-rolled and cold rolled seamless steel pipe points (written) seamless steel categories. Hot-rolled seamless steel tube sub-normal, low, medium pressure boiler pipe, high pressure boiler steel pipes, steel pipes, stainless steel pipe, oil cracking pipe, steel and other steel and other geological. Cold-rolled (allocated) Subject to sub-general seamless steel pipe, low and medium pressure boiler pipe, high pressure boiler steel pipes, steel pipes, stainless steel pipe, oil cracking pipe, the other steel, but also includes carbon thin-walled steel pipe, alloy thin-walled steel pipe, thin-walled stainless steel, special steel pipe. Hot rolled seamless pipe diameter is generally greater than 32mm, wall thickness 2.5-75mm, cold-rolled seamless steel pipe diameter can go to 6mm, wall thickness can be 0.25mm, outer diameter thin-walled tube to 5mm thickness can be less than 0.25mm , cold than hot-rolled high dimensional accuracy. Seamless is 10,20,30,35,45 general and other high quality carbon steel 16Mn, 5MnV low-alloy structural steel or 40Cr, 30CrMnSi, 45Mn2, 40MnB and other hot-rolled or cold-rolled structural steel made. 10,20 and other low-carbon steel seamless pipe is mainly used for fluid pipes. 45,40 Cr, etc. made of carbon steel seamless pipe used in the manufacture of mechanical parts, such as cars, tractors and the force components. General seamless steel pipes to ensure the strength and flattening test. Hot-rolled steel with hot-rolled state or heat treatment delivery; cold to heat treatment delivery. Hot, by definition, high temperature rolling, so the deformation resistance is small, can achieve a large deformation. The steel rolling, for example, generally about 230mm slab thickness, and after a rough rolling and finish rolling, the final thickness of 1 ~ 20mm. Meanwhile, the steel plate thickness ratio is small, relatively low accuracy requirements size, shape problems are not prone to control the convexity-based. Requirements for the organization, usually by controlled rolling and cooling to achieve that control the opening and finishing rolling temperature, finish rolling temperature and coiling temperature to control the strip microstructure and mechanical properties.