Carbon steel pipes are divided into hot rolled and cold rolled (drawn) steel pipes. Hot rolled carbon steel pipe is divided into general steel pipe, low and medium pressure boiler steel pipe, high pressure boiler steel pipe, alloy steel pipe, stainless steel pipe, petroleum cracking pipe, geological steel pipe and other steel pipes. Cold rolled (dial) carbon steel pipe in addition to general steel pipe, low and medium pressure boiler steel pipe, high pressure boiler steel pipe, alloy steel pipe, stainless steel pipe, oil cracking pipe, other steel pipe, also includes carbon thin-wall steel pipe, alloy thin-wall steel pipe, stainless thin-wall steel pipe, special-shaped steel pipe. The outer diameter of the hot-rolled seamless pipe is generally greater than 32mm, the wall thickness is 2.5-75mm, the outer diameter of the cold-rolled seamless steel pipe can be 6mm, the wall thickness can be 0.25mm, the outer diameter of the thin-walled pipe can be 5mm, the wall thickness is less than 0.25mm, and the size accuracy is higher than that of the hot-rolled seamless pipe.