Cold rolled (dialed) seamless steel pipes include general steel pipes, low and medium pressure boiler pipes, high pressure boiler pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes and other steel pipes. 
They also include carbon thin-walled steel pipes, alloy thin-walled steel pipes, stainless thin-walled steel pipes and profiled steel pipes. The outer diameter of hot-rolled seamless pipe is generally larger than 32 mm, the wall thickness is 2.5-75 mm, the outer diameter of cold-rolled seamless pipe can reach 6 mm, the wall thickness can reach 0.25 mm, the outer diameter of thin-walled pipe can reach 5 mm, the wall thickness is less than 0.25 mm, and the dimension precision of cold-rolled seamless pipe is higher than that of hot-rolled pipe.