API 5L — Specification for line pipe (harmonised with ISO 3183)
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Scope
Specification for seamless and welded steel line pipe for the pipeline transport of petroleum, natural gas and water. Grades are named by specified minimum yield strength in two parallel systems — L245 / Grade B, L290 / X42, L320 / X46, L360 / X52, L390 / X56, L415 / X60, L450 / X65, L485 / X70, L555 / X80. Every grade is ordered at one of two product specification levels: PSL1 sets minima, chemistry ceilings and a hydrostatic test; PSL2 adds a maximum yield strength, a yield-to-tensile ratio cap, a carbon equivalent limit, mandatory Charpy impact testing, drop-weight tear testing on larger sizes and tighter sulphur. Annex H covers sour service (suffix S) and Annex J offshore service (suffix O). Delivery conditions N, Q and M and manufacturing routes S, HFW, SAWL and SAWH are part of the designation.
Grades covered by API 5L
| Grade | No. | Type | C % | Yield MPa | Tensile MPa | Nearest equivalents |
|---|---|---|---|---|---|---|
| L360 / X52 | — | Line pipe steel, 360 MPa minimum yield | ≤ 0.24 | 360 | 460 | L360NB / L360MB, s355j2h, a106-b |
Revision history and superseded standards
| Year | Change |
|---|---|
| pre-1980s | three separate specifications: 5L (Grades A, B), 5LX (X42-X70), 5LS (spiral) |
| 1990s | 5LX and 5LS merged into 5L; PSL1 and PSL2 introduced |
| 2007 | harmonised with ISO 3183; the L designations adopted alongside the X designations |
| current | 46th edition; X80 and strain-based design annexes in force |
Supersedes: API 5LX (withdrawn — high strength line pipe); API 5LS (withdrawn — spiral welded line pipe); DIN 17172 (StE 360.7 and related German line pipe grades).
Where to buy the standard
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