Chemical Composition of API 5L X52
1. PSL1 (Conventional Grade)
Carbon (C):
Seamless steel pipe: ≤ 0.28%
Welded steel pipe: ≤ 0.26%
Manganese (Mn): ≤ 1.40% (if the carbon content is lower than 0.01%, the manganese content can be increased by 0.05%, with a maximum of 1.65%)
Phosphorus (P): ≤ 0.030%
Sulphur (S): ≤ 0.030%
Other elements:
Copper (Cu), nickel (Ni), chromium (Cr): all ≤ 0.50%
Molybdenum (Mo): ≤ 0.15%
Vanadium (V) + niobium (Nb) + titanium (Ti): the sum of ≤ 0.15%
2. PSL2 (High Demand Grade, such as X52N/L360N)
Carbon (C): ≤ 0.24%
Silicon (Si): ≤ 0.45%
Sulfur (S): ≤ 0.015% (stricter than PSL1)
Other elemental restrictions are consistent with PSL1, but some testing requirements are more stringent (such as low-temperature impact toughness).
3. Special Instructions
The carbon content of welded steel pipe needs to be more strictly controlled (≤ 0.26%) to reduce the risk of weld cracking.
Micro-alloying: niobium (Nb), vanadium (V) and other elements may be added in some manufacturing to improve strength (provided that the sum ≤ 0of these elements does not exceed 15%)
