Seamless steel pipes Hot-rolled seamless 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 ordinary 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, there are also cold-rolled (rolled) seamless steel pipes including carbon thin-walled steel pipes, alloy thin-walled steel pipes, Stainless steel thin-walled steel pipes, special-shaped steel pipes. The outer diameter of hot-rolled seamless steel 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 tubes can reach 5mm and the wall thickness is less than 0.25mm. Cold rolling has higher dimensional accuracy than hot rolling.
Ordinary seamless steel pipes: use 10, 20, 30, 35, 45, 16Mn, 5MnV and other low-alloy structural steel hot-rolled or cold-rolled high-quality carbon structural steel or 40Cr, 30CrMnSi, 45Mn2, 40MnB and other alloy steel. Seamless pipes made of grade 10 and 20 low carbon steel are mainly used for fluid transportation pipelines. Medium carbon steel seamless pipes such as 45 and 40Cr are used to manufacture mechanical parts, such as stressed parts of automobiles and tractors. Generally, seamless steel pipes must 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.
