API 5L standard is the standard specification of seamless and welded steel pipes for pipeline transportation system in oil and gas industry formulated by api gravity (API).
This standard specifies the requirements for steel pipes used to transport liquids and gases, including the dimensions, chemical composition, mechanical properties, manufacturing technology and so on. API 5L standard is suitable for steel pipes with nominal size (NPS) of 1/8 to 60(DN 6 to DN 1500), and its manufacturing materials usually adopt open hearth furnace, basic oxygen converter or electric furnace smelting process.
API 5L standard divides steel pipes into two product specification levels: PSL1 and PSL2. PSL1 is the standard quality level of pipelines, while PSL2 contains additional chemical and mechanical properties and testing requirements, which are more stringent for the quality of steel pipes. The steel grades covered by this standard are A25, A, B and "X" steels, such as X42, X46, X52, X56, X60, X65, X70, X80, etc. The two digits after "X" indicate the minimum yield strength (unit: 000psi).