API PSL2 is the product specification level 2 in API 5L standard formulated by api gravity (API), and it is an enhanced quality standard for seamless and welded steel pipes used for conveying fluids in oil and gas industry.
The PSL2 standard has stricter requirements for steel pipes in high-risk and corrosive environments. In terms of chemical composition, fine-grained killed steel is used, and the contents of carbon, sulfur and phosphorus are strictly limited, such as carbon content ≤0.24%, phosphorus content ≤0.02% and sulfur content ≤0.015%. In terms of mechanical properties, not only the minimum strength is specified, but also the maximum strength and the upper limit of yield ratio are defined to ensure that the material has both strength and toughness. For example, the yield strength of X52 steel grade PSL2 steel pipe is required to be ≥460MPa, while PSL1 only requires ≥414MPa.
Additional impact test and drop weight tear test (DWTT) are required for PSL2 steel pipe to verify the fracture resistance of the material at low temperature or high pressure, such as longitudinal impact work ≥41J at-20℃. At the same time, PSL2 steel pipes shall be subjected to comprehensive nondestructive testing one by one, such as ultrasonic flaw detection, to ensure that there are no internal defects. In addition, each steel pipe should be subjected to water pressure test, and the test pressure is 1.5 times of the design pressure.
The steel grade covered by PSL2 standard ranges from B to X80, and it is suitable for severe working conditions such as deep-sea platforms, high-pressure gas pipelines and highly corrosive environments containing hydrogen sulfide (HS). Although the initial cost of PSL2 steel pipe is about 10%-20% more expensive than PSL1, its longer service life and lower maintenance requirements make its comprehensive cost more advantageous.