Seamless steel pipe is divided into hot-rolled pipe and cold-drawing pipe by the manufacturing methods. The largest nominal diameter of cold-drawing pipe is 200mm, hot-rolled pipe with 600 mm. In the pipeline project, when the diameter is more than 57mm, the hot-rolled tube is the regular selection; otherwise, the cold-drawing tube. Seamless steel pipe commonly used in pipeline projects has the following three types:

General seamless steel pipe: general seamless steel pipe is usually called seamless steel pipe. It is made of ordinary carbon steel, quality carbon steel, ordinary low-alloy steel and alloy structural steel. We usually use it to produce liquid transportation pipelines or the production structure, and parts.

Seamless steel pipe for low and medium-pressure boiler: it is usually made of steel No. 10, 20. Hot-rolled steel is delivered in hot rolled state and cold-rolled steel is delivered in cold rolled state.

Seamless steel pipe for high-pressure boiler: it is mainly used for making quality carbon structural steel, alloy steel and heat-resistant stainless steel. The pipe is delivered in hot rolled state. Otherwise, it has definite requirements for microscopic structure, grain size, and decarburized layer.