What do the common suffixes for API 5L X52 pipes mean?

The common suffixes of API 5L X52 pipes are as follows and their meanings:
Suffixes indicating delivery status
N: stands for normalizing status. For example, X52N means that the pipe has been normalized. Normalizing can refine the grains, so that the pipe has good strength, toughness and fatigue resistance, etc., and is often used in occasions with certain requirements for comprehensive performance.
M: stands for deformation heat treatment status. Through the combination of special thermal deformation and heat treatment processes, the strength and toughness of the pipe can be further improved, which is suitable for high-pressure, high-strength transportation and other application scenarios with high requirements for pipe performance.
Q: stands for quenching and tempering status. Quenching can significantly improve the strength of the pipe, and tempering can eliminate quenching stress, improve toughness and plasticity, so that the pipe has good comprehensive mechanical properties, and is often used in special working conditions with high requirements for strength and toughness.
Suffix indicating product specification level
PSL1: This is the mark of product specification level 1. PSL1 has basic requirements for the chemical composition, mechanical properties, dimensional tolerances, etc. of the pipe, and is suitable for more conventional applications such as general oil and gas pipelines.
PSL2: The symbol of product specification level 2. Compared with PSL1, PSL2 has stricter control over chemical composition, and has higher requirements for tensile properties, impact energy, non-destructive testing and other indicators. It is usually used in harsher environments, more complex conveying media, or occasions with higher requirements for pipeline safety and reliability, such as submarine oil and gas pipelines.