API 5L generally refers to the implementation standard of line pipes, which are pipelines used to transport oil, steam, water, etc. extracted from the ground to oil and natural gas industrial enterprises. Line pipes include seamless steel pipes and welded steel pipes. At present, the commonly used welded steel pipe types in oil pipelines in China include spiral submerged arc welded pipe (SSAW), longitudinal submerged arc welded pipe (LSAW), and electric resistance welded pipe (ERW). Seam steel pipes are generally selected when the pipe diameter is less than 152mm.

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

　　As everyone knows about API 5L, there are two standards, PSL1 and PSL2. Although there is only one word difference, the content of these two standards is very different. This is similar to the GB/T9711.1.2.3 standard. They all talk about the same thing, but the requirements are very different. Now I will talk about the difference between PSL1 and PSL2 in detail:

　　1. PSL is the abbreviation for product specification level. The product specification level of line pipe is divided into PSL1 and PSL2, it can also be said that the quality level is divided into PSL1 and PSL2. PSL2 is higher than PSL1. These two specification levels are not only different in inspection requirements, but also in chemical composition and mechanical properties. Therefore, when ordering according to API 5L, the terms in the contract shall not only indicate the usual indicators such as specifications and steel grades. , Must also indicate the product specification level, that is, PSL1 or PSL2. PSL2 is stricter than PSL1 in indicators such as chemical composition, tensile properties, impact energy, and non-destructive testing.

　　2, PSL1 does not require impact performance, PSL2 all steel grades except x80, full-scale 0℃ Akv average value: longitudinal ≥ 41J, transverse ≥ 27J. X80 steel grade, full-scale 0℃ Akv average value: longitudinal ≥ 101J, transverse ≥ 68J.

　　3. Line pipes should be subjected to water pressure test one by one, and the standard does not stipulate allow non-destructive test substitute water pressure. This is also a big difference between the API standard and the Chinese standard. PSL1 does not require non-destructive inspection, PSL2 should be non-destructive inspection one by one.