An API (American Petroleum Institute) 5L line pipes are manufactured in two forms, PSL 1 and PSL 2. PSL stands for Product Specification Levels. PSL stands for Product Specification Levels. These specs cover seamless and welded steel line pipe from grades X42 through X80. API 5L is suitable for transporting gas, water, and oil, and is usually found in the hydrocarbon petroleum and natural gas industry.
PSL-1 is a loose standard quality for line pipe, whereas PSL-2 contains additional testing requirement, stricter chemical physicals, along with different ceiling limits of mechanical properties, and require Charpy impact testing conditions.
Furthermore, additional testing requirements under PSL-2 include CVN testing, non-destructive inspection of seamless products, certification to SR15, and mandatory traceability throughout the entire production process. Most FERC, DOT, or FEMSA lines require PSL-2, meaning these types of requirements are a must when supplying pipe for pipelines that are regulated by any of these governing bodies.
| Parameter | PSL 1 | PSL 2 |
| Grade range | A25 through X70 | B through X80 |
| Max C for Seamless pipe | 0.28% for grades ≥ B | 0.24% |
| Max C for Welded pipe | 0.26% for grades ≥ B | 0.22% |
| Max P | 0.030% for grades ≥ A | 0.03% |
| Max S | 0.03% | 0.02% |
| Carbon Equivalent | Only when purchaser specifies SR18 | Maximum required for each grade |
| Yield Strength, Max | None | Maximum for each grade |
| UTS (Ultimate Tensile Strength), Max | None | Maximum for each grade |
| Size Range | 0.405″ through 80″ | 4.5″ through 80″ |
| Type of Ends | Plain end, Threaded end, Bevelled end special coupling pipe | Plain End |
| Seam Welding | All methods: continuous welding limited to A25 | All methods: except continuous welding and laser welding |
| Electric Welds: Welder frequency | No Minimum | kHz minimum 100 |
| Heat Treatment of Electric Welds | Required for grades >X42 | Required for all grades (B through X80) |
| Fracture Toughness | None | Required for all grades |
| Traceability | Traceable only until all tests are passed unless SR15 is specified | Traceable after completion of tests (SR15.2) mandatory |
| Certification | Traceable only until all tests are passed | Certificates (SR15.1) mandatory |
| Non-Destructive Inspection of Seamless | Only when purchaser specifies SR4 | SR4 mandatory |
| Repair by Welding of Pipe Body Plate and Skelp | Permitted by agreement | Prohibited |
| Repair by Welding of Weld Seams without Filler Metal | Permitted by agreement | Prohibited |
