API 5L steel pipe specification

　　In API Spec 5L 2012, the scope is defined as "the requirements of two product specification levels (PSL1 and PSL2) for the manufacture of seamless and welded steel pipes for pipeline transportation systems in the oil and gas industry. This standard does not apply to cast pipes. "

　　In short, API 5L pipe is a carbon steel pipe used in oil and gas transmission system. At the same time, other fluids such as steam, water and slurry can also be transmitted according to API 5L standard.

　　Different types of manufacturing

　　API 5L specification covers welding and seamless manufacturing types.

　　The common types of welded pipe are SSAW, LSAW and ERW.

　　Check here for differences between ERW, LSAW and SSAW piping.

　　On the other hand, API 5L Gr. B Seamless Steel Line Pipe is commonly used for small diameter pipes (pipe diameter is less than 150 mm or 6 inches, and seamless steel pipes are used more than steel pipes in welding.)

　　For your information, there are also large caliber seamless tubes. Through the hot rolling manufacturing process, we can obtain seamless pipes with a maximum diameter of 20 inches (508 mm). However, if you need more than 20 inches of seamless pipe, we can get it through the thermal expansion process, with a maximum diameter of 40 inches 1016 mm.

　　API 5L pipeline manufacturing development

　　In addition to seamless and ERW, saw manufacturing technology, the earliest API 5L steel pipe can also be manufactured by furnace lap welding (deleted in API 5L in 1962).

　　With the development of pipe steel plate manufacturing technology, the pipe forming and welding technology has been greatly improved, so ERW pipe and saw pipe are widely used in the pipeline construction. Especially for large-diameter steel pipe, saw pipe has great advantages. Welded steel pipes occupy the first place in the oil and gas pipeline industry with low cost of raw materials, simplified production process and unified process.

　　API 5L covers different grades

　　API 5L steel pipe adopts different steel grades, generally gr. B，X42，X46，X52，X56，X60，X65，X70，X80。 Some manufacturers are able to produce grades up to X100 and X120. With the improvement of steel pipe grade, the control of carbon equivalent is more strict, and the mechanical strength performance is higher and higher.

　　In addition, for the same grade of API 5L pipe, the content of seamless and welding chemical elements is different, which requires more strict requirements for welded pipe, while the content of carbon and sulfur is lower.

　　Through different delivery conditions, rolling, normalizing rolling, thermomechanical rolling, normalizing forming, normalizing, normalizing tempering, quenching and tempering can also be carried out.