Line pipe is a world of its own inside carbon steel, and the X-grades are how it measures strength. Metinox Overseas supplies carbon steel API 5L X-series line pipe in grades B through X70, PSL1 and PSL2, seamless and welded, with 3.1 certification and export lanes to the USA, the Middle East and Africa. API 5L is the specification for pipe that transports oil, gas and water between points, and its X-grade system labels each grade by minimum yield strength, so a pipeline designer can trade wall thickness against grade to hit a pressure at the lowest installed cost. The general carbon range sits at Carbon Steel Pipes & Tubes.
Two honest boundaries. API 5L is a transmission and structural steel, not a high-temperature one; hot service still belongs to the chrome-moly grades on Alloy Steel Pipes, and corrosive service to Stainless Steel Pipes. Within ambient pipeline and structural duty, this page is where strength meets economy.
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Table of content
- The API 5L X-Grade Strength Ladder
- PSL1 vs PSL2: The Quality Level Decision
- The API Monogram and What It Means
- API 5L Chemistry & Line Pipe Sizes
- Sour Service: PSL2 & NACE MR0175
- API 5L Line Pipe Applications & Export to USA, Middle East & Africa
- Explore Related Ranges
- Carbon Steel API 5L X-Series Pipe: Frequently Asked Questions
The API 5L X-Grade Strength Ladder
The number after the X is the minimum yield strength in thousands of psi, and that is the whole logic: climb the ladder for a stronger steel that lets you use a thinner wall or carry a higher pressure. Higher grades cost more per tonne but can lower the delivered cost of a pipeline by reducing steel weight.
| Grade | Min Yield (psi) | Min Yield (MPa) | Typical use |
|---|---|---|---|
| Gr B | 35,000 | 245 | Utility and lower-pressure lines, structural |
| X42 | 42,000 | 290 | Gathering and distribution |
| X52 | 52,000 | 359 | The common transmission grade |
| X60 | 60,000 | 414 | Higher-pressure transmission |
| X65 | 65,000 | 448 | Long-distance and offshore trunk lines |
| X70 | 70,000 | 483 | High-pressure, large-diameter transmission |
X80 and above exist for the highest-specification trunk lines and are supplied against project order. Match the grade to the design pressure and the wall thickness calculation, not to habit.
PSL1 vs PSL2: The Quality Level Decision
API 5L sells two product specification levels, and the difference is how tightly the steel is controlled. PSL1 is the basic level with standard chemistry and testing. PSL2 adds tighter limits on chemistry, mandatory notch-toughness (Charpy) testing, controlled carbon equivalent for weldability, and stricter non-destructive examination, and it is required for most modern transmission and any critical or sour service. The two are not interchangeable: a PSL2 line specified as PSL1 loses the toughness and weldability guarantees the pipeline was designed around. State the PSL level with the grade, always.
The API Monogram and What It Means
The API monogram on a pipe is a licensing mark: it certifies that the manufacturer operates under API's quality system and that the pipe was made to the full API 5L requirements for its grade and level. For pipeline work it is frequently a contractual requirement, not a nicety, because it is the buyer's assurance that X65 PSL2 on the certificate means X65 PSL2 in the ditch. Our supply is documented to API 5L with full traceability; the quality program is on our Quality Policy page.
Sour Service: PSL2 & NACE MR0175
Where a pipeline carries sour hydrocarbons, hydrogen sulphide brings the risk of sulphide stress cracking and hydrogen-induced cracking, and the material must be qualified for it. Sour-service API 5L is supplied to PSL2 with the additional NACE MR0175 / ISO 15156 requirements, controlled hardness and HIC-resistant steel making, arranged at order stage. Where the sour environment is also wet and corrosive rather than only cracking-prone, the design may move to a clad or corrosion-resistant alloy line instead, on the stainless or nickel-alloy side. Say sour in the enquiry and the qualification is built into the quote.
API 5L Line Pipe Applications & Export to USA, Middle East & Africa
- Oil & Gas Transmission: cross-country and gathering lines across Gulf, African and Indian fields, X52 to X70.
- Water Pipelines: large-diameter transmission mains, an African infrastructure lane.
- Offshore & Subsea: trunk lines in X65 and X70 PSL2.
- Structural & Piling: Gr B and X42 for structural and casing duty.
- Slurry & Utility: mine and plant transfer lines.
Every order ships with EN 10204 3.1 and API 5L documentation; see Quality Policy. Consolidations run from Mumbai to the USA, the Middle East and Africa, oiled, strapped and end-protected per Packing and Dispatch. Ex-stock dispatches in 7 to 14 working days; X grades and PSL2 take 4 to 6 weeks.
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Carbon Steel API 5L X-Series Pipe: Frequently Asked Questions
The number after the X is the minimum yield strength in thousands of psi. X52 has a 52,000 psi minimum yield, X65 has 65,000, and so on up. A higher grade is a stronger steel, letting a designer use a thinner wall or carry a higher pressure, which can lower the installed cost of a pipeline despite the higher price per tonne.
Quality level. PSL1 is the basic specification with standard chemistry and testing. PSL2 adds tighter chemistry limits, mandatory Charpy notch-toughness testing, controlled carbon equivalent for weldability, and stricter NDE, and it is required for most modern transmission and all sour service. The two are not interchangeable; specifying a PSL2 line as PSL1 loses the guarantees it was designed around.
It is a licensing mark certifying that the pipe was made under API's quality system to full API 5L requirements. For pipeline work it is frequently a contractual requirement, because it is the buyer's assurance that the grade and level on the certificate are real. Our supply is documented to API 5L with full traceability.
Yes, when qualified for it. Sour-service API 5L is supplied to PSL2 with NACE MR0175 / ISO 15156 requirements, controlled hardness and HIC-resistant steelmaking, to resist sulphide stress cracking and hydrogen-induced cracking. Where the sour stream is also wet and corrosive, a clad or corrosion-resistant alloy line may be specified instead.
Yes, on regular consolidations from Mumbai with EN 10204 3.1 and API 5L documentation. Oil and gas transmission in the Gulf and Africa, water pipelines across Africa, and structural and offshore work in all three regions are the regular lanes, shipped oiled and end-protected.
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