What Is API 5L Grade X52?
API 5L Grade X52 is a medium-strength carbon steel line pipe grade specified in API 5L for oil and gas transmission pipelines. The “X52” designation means the pipe has a minimum yield strength of 52 ksi (359 MPa). It is one of the most commonly used grades for onshore gathering and transmission pipelines operating at moderate pressures.
Grade X52 is available in seamless, ERW, and LSAW manufacturing methods, in both PSL1 and PSL2 product specification levels.
Mechanical Properties
| Property | X52 PSL1 | X52 PSL2 |
|---|---|---|
| Yield strength (min) | 359 MPa (52 ksi) | 359 MPa (52 ksi) |
| Yield strength (max) | Not specified | 531 MPa (77 ksi) |
| Tensile strength (min) | 455 MPa (66 ksi) | 455 MPa (66 ksi) |
| Tensile strength (max) | Not specified | 600 MPa (87 ksi) |
| Y/T ratio (max) | Not specified | 0.93 |
| Elongation (min) | Per API 5L table | Per API 5L table |
| Charpy impact | Not required | Required (per table) |
| Hardness (max) | Not specified | 250 HV10 (sour: 248 HV10) |
Chemical Composition
| Element | X52 PSL1 (max %) | X52 PSL2 (max %) |
|---|---|---|
| Carbon | 0.28 | 0.24 |
| Manganese | 1.40 | 1.40 |
| Phosphorus | 0.030 | 0.025 |
| Sulfur | 0.030 | 0.015 |
| Titanium | 0.04 | 0.04 |
| Niobium | 0.05 | 0.05 |
| Vanadium | 0.10 | 0.10 |
| CE (IIW) | 0.43 | 0.43 |
| Pcm | Not specified | 0.25 |
PSL2 has tighter limits on carbon, phosphorus, and sulfur, resulting in better weldability, toughness, and sour service suitability.
Where X52 Fits Among API 5L Grades
| Grade | Yield (min, MPa) | Typical Application |
|---|---|---|
| B | 245 | Low-pressure gathering, utilities |
| X42 | 290 | Gathering lines, distribution |
| X46 | 317 | Medium-pressure gathering |
| X52 | 359 | Transmission, gathering, process |
| X56 | 386 | Transmission pipelines |
| X60 | 414 | High-pressure transmission |
| X65 | 448 | High-pressure, offshore |
| X70 | 483 | Long-distance, high-pressure |
| X80 | 552 | Ultra-high-pressure trunk lines |
X52 is the transition grade between low-pressure gathering systems and high-pressure transmission pipelines. It offers a good balance of strength, weldability, and cost.
Manufacturing Methods
| Method | Size Range | Application |
|---|---|---|
| Seamless | NPS 2 to NPS 16 | Small to medium bore gathering |
| ERW | NPS 2 to NPS 24 | Medium-diameter pipelines |
| LSAW | NPS 16 to NPS 64 | Large-diameter transmission |
| SSAW (spiral) | NPS 16 to NPS 120 | Water, low-pressure gas |
Applications
- Onshore oil and gas gathering pipelines
- Medium-pressure gas transmission (up to 80-100 bar design pressure)
- Produced water and multiphase flow lines
- Pipeline station and terminal piping
- Pipeline bends and fabricated fittings
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