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 (rolled) carbon steel pipes also include carbon thin-walled steel pipes, alloy thin-walled steel pipes, and stainless steel pipes. Rusty thin-walled steel pipes, special-shaped steel pipes. The outer diameter of hot-rolled seamless steel pipes is generally greater than 32mm, and the wall thickness is 2.5-75mm. The outer diameter of cold-rolled seamless steel pipes can be up to 6mm, and the wall thickness can be up to 0.25mm. The outer diameter of thin-walled pipes can be up to 5mm, and the wall thickness is less than 0.25mm. Cold rolling has higher dimensional accuracy than hot rolling.