Carbon steel pipes are made by piercing steel ingots or solid round steel into rough tubes, and then hot-rolled, cold-rolled or cold-drawn. Generally, carbon steel pipes are made by hot-rolling or cold-rolling high-quality carbon structural steel such as 10, 20, 30, 35, 45, low alloy structural steel such as 16Mn, 5MnV or alloy steel such as 40Cr, 30CrMnSi, 45Mn2, 40MnB. Seamless pipes made of low carbon steel such as 10 and 20 are mainly used for fluid transportation pipelines. Seamless pipes made of medium carbon steel such as 45 and 40Cr are used to manufacture mechanical parts, such as load-bearing parts of automobiles and tractors. [1] Carbon steel pipes have an important position in my country's steel pipe industry.
CO2 transportation pipelines mainly use high-frequency resistance welded pipes (HFW), and the steel grade is usually X65～X80. In May 2023, my country carried out the first full-size burst test of a CO2 pipeline in China. The pipeline was an HFW welded pipe with a specification of Φ323.9 mm and X65 steel grade. Hydrogen transportation pipelines are generally made of low-grade carbon steel and low-alloy steel welded or seamless pipes.