What Is API 5L? Line Pipe Specification
API 5L is the specification for line pipe used in pipeline transportation systems for oil, gas, and water. Published by the American Petroleum Institute, it is the global standard for pipeline pipe and covers seamless, welded (ERW/HFW), and submerged arc welded (LSAW, DSAW, SSAW) manufacturing methods.
API 5L defines two Product Specification Levels (PSL1 and PSL2) with PSL2 imposing stricter requirements on chemistry, mechanical properties, and testing.
| Property | Detail |
|---|---|
| Scope | Steel pipe for pipeline transportation |
| Manufacturing | Seamless (SMLS), ERW/HFW (EW), SAW (SAWL, SAWH) |
| Size range | NPS 1/8 to NPS 80+ (OD 10.3 to 2032+ mm) |
| PSL levels | PSL1 (standard), PSL2 (enhanced) |
| Grades | A, B, X42, X46, X52, X56, X60, X65, X70, X80 |
| Design code | ASME B31.4 (liquid), B31.8 (gas), DNV-OS-F101 (submarine) |
| Current edition | 46th Edition (ISO 3183 aligned) |
Grade System
The “X” number represents the minimum yield strength in ksi. For example, X65 has a minimum yield strength of 65 ksi (448 MPa).
| Grade | Min. Yield Strength | Min. Tensile Strength |
|---|---|---|
| A | 207 MPa (30 ksi) | 331 MPa (48 ksi) |
| B | 241 MPa (35 ksi) | 414 MPa (60 ksi) |
| X42 | 290 MPa (42 ksi) | 414 MPa (60 ksi) |
| X52 | 359 MPa (52 ksi) | 455 MPa (66 ksi) |
| X60 | 414 MPa (60 ksi) | 517 MPa (75 ksi) |
| X65 | 448 MPa (65 ksi) | 531 MPa (77 ksi) |
| X70 | 483 MPa (70 ksi) | 565 MPa (82 ksi) |
| X80 | 552 MPa (80 ksi) | 621 MPa (90 ksi) |
PSL1 vs PSL2
The Product Specification Level determines the stringency of requirements. See the full comparison in API 5L PSL1 vs PSL2.
Key differences:
- PSL2 mandates maximum yield and tensile strength limits (not just minimums)
- PSL2 requires Charpy impact testing
- PSL2 has tighter chemistry limits (lower carbon equivalent)
- PSL2 requires non-destructive testing per specific acceptance criteria
Applications
- Onshore oil and gas transmission pipelines
- Offshore and subsea pipelines
- Gas distribution networks
- Water transmission mains
- Gathering and flow lines in upstream operations
API 5L is the pipeline counterpart to ASTM A106 (refinery process piping) and ASTM A53 (general service). Many mills dual-certify pipe to API 5L and ASTM A106 or A53 where chemistry and mechanical properties overlap.
Leave a Comment
Have a question or feedback? Send us a message.