API 5L generally refers to the executive standard of pipeline steel pipe. Pipeline steel pipe is used to transport oil, steam, water, etc. extracted from the ground to oil and gas industrial enterprises. Pipeline steel pipes include seamless steel pipes and welded steel pipes. At present, the commonly used welded steel pipe types on oil pipelines in China include spiral submerged arc welded pipe (SSAW), longitudinal submerged arc welded pipe (LSAW) and resistance welded pipe (ERW). Seamless steel pipes are generally selected when the pipe diameter is less than 152mm.
There are many kinds of steel grades of raw materials for steel pipes of API 5L standard, such as GR. B, X42, X46, X52, X56, X60, X70, X80, etc. Now large steel plants such as Baosteel have developed pipeline steel with steel grades of X100 and X120. 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.
When it comes to API 5L, we all know that there are two standards under it, PSL1 and PSL2. Although there is only a word difference, the contents of the two standards are very different. This is similar to the GB/T9722.214.171.124 standard. They all say the same thing, but the requirements are thousands of miles away. Now I’ll talk about the differences between PSL1 and PSL2 in detail:
- PSL is the abbreviation of product specification level. The product specification level of pipeline pipe is divided into PSL1 and PSL2, which can also be said that the quality level is divided into PSL1 and PSL2. PSL2 is higher than PSL1. The two specification levels are not only different in terms of inspection requirements, but also different in terms of chemical composition and mechanical properties. Therefore, when ordering according to API 5L, the terms in the contract must indicate the product specification level, that is, PSL1 or PSL2, in addition to the usual indicators such as specification and steel grade. PSL2 is stricter than PSL1 in chemical composition, tensile property, impact energy, NDT and other indicators.
- Impact performance is not required for PSL1. For all steel grades except x80, the average value of full size 0 ℃ Akv: longitudinal ≥ 41J, transverse ≥ 27J. X80 steel grade, full size 0 ℃ Akv average value: longitudinal ≥ 101J, transverse ≥ 68J.
- Hydrostatic test shall be carried out for pipeline pipes one by one, and the standard does not stipulate that nondestructive water pressure replacement is allowed, which is also a big difference between API standards and Chinese standards. PSL1 does not require NDT, and PSL2 shall conduct NDT one by one.