1. API 5L: API 5L is a pipeline pipe standard developed by the American Petroleum Institute.

2. X42: X42 is a steel grade of standard steel pipes. The steel grades in API 5L mainly include: A, B, X42, X46, X52, X56, X60, X65, X70, X80, X90, X100, X120, etc. His naming convention is basically based on the capital letter X plus the minimum yield strength of the material. Of course, the difference between different steel grades is not only in yield strength, but also in manufacturing process, chemical composition, physical properties, inspection methods, and other aspects.

3. PSL2: When formulating API 5L, it was considered that there are two basic levels of standard technical requirements for pipeline pipes, therefore two product specification levels of technical requirements were established: PSL1 and PSL2. PSL1 provides general pipeline quality level requirements. PSL2 includes mandatory requirements for increased chemical composition, notch toughness, strength performance, and supplementary NDE.