API 5L generally refers to the implementation standard of pipeline steel pipes. Pipeline steel pipes are used to transport oil, steam, water, etc. extracted from the ground to oil and gas industry enterprises. Pipeline steel pipes include seamless steel pipes and welded steel pipes. At present, the welded steel pipes commonly used in oil pipelines in my country include spiral submerged arc welded pipes (SSAW), straight seam submerged arc welded pipes (LSAW), and electric resistance welded pipes (ERW). Seam steel pipe is generally selected when the diameter of the pipe is less than 152mm.

There are many kinds of steel grades for raw materials of API 5L steel pipes: GR.B, X42, X46, X52, X56, X60, X70, X80, etc. Now large steel mills like Baosteel have developed steel grades of X100, X120 pipeline steel. The steel grades of steel pipes are different, the requirements for raw materials and production are higher, and the carbon equivalent between different steel grades is strictly controlled.