What do the suffix letters of the X52 pipe mean?

Product specification level related
PSL1 and PSL2: PSL is the abbreviation of product specification level.
PSL1: represents the basic product specification level. Generally speaking, its chemical composition, mechanical properties and other requirements are relatively basic, and the production and inspection requirements are relatively loose. For example, PSL1 does not require impact performance testing.
PSL2: is a higher level of product specification level. It is stricter than PSL1 in terms of chemical composition, tensile properties, impact energy, non-destructive testing and other indicators. For example, for all steel grades except X80 in PSL2, the average value of full-size 0℃ Akv is ≥41J longitudinally and ≥27J transversely, and non-destructive testing should be carried out on each steel.
Corrosion resistance related
NS and QS: When the suffix "NS" or "QS" appears, it is often related to corrosion resistance, especially resistance to sulfide stress corrosion cracking (SSC) and hydrogen-induced cracking (HIC).
NS: For example, X52NS indicates that the pipe is suitable for acid service environment and is an acid-resistant line pipe. It adopts a special production process and component design to meet the use requirements in acidic media environments such as hydrogen sulfide. It has the characteristics of low-sulfur, high-purity steel and calcification treatment.
QS: The meaning is similar to NS. It is also a mark used in specific corrosive environments, indicating that the pipe has special design and treatment in terms of corrosion resistance.

Suffix letter with each grade describe the API 5L X52 Pipe delivery condition