Products Features
Good strength and toughness match (core advantage)
The core advantage of API 5L X52 lies in its excellent balance between strength and toughness. Thanks to its low-carbon micro-alloyed design (carbon content ≤ 0.16-0.28%) and TMCP controlled rolling and cooling process, X52 maintains good low-temperature impact toughness while ensuring a minimum yield strength of 360 MPa and a minimum tensile strength of 460 MPa. Its yield strength is approximately 1.24 times that of X42 (290 MPa), making it an ideal material for medium-pressure transmission applications.
|
Performance indicators |
PSL1 Requirements |
PSL2 Requirements |
|
Minimum Yield Strength (MPa) |
360 |
360 |
|
Maximum Yield Strength (MPa) |
- |
530 |
|
Minimum Tensile Strength (MPa) |
460 |
460 |
|
Maximum Tensile Strength (MPa) |
- |
760 |
|
Yield ratio |
- |
Typically ≤ 0.90-0.93 |
|
Elongation |
≥ 23% |
≥ 23% |
Note: PSL2 imposes limits on both maximum yield strength and maximum tensile strength (with upper limits of approximately 530 MPa and 760 MPa, respectively), ensuring the material has sufficient plastic deformation capacity and a higher safety margin to avoid brittle failure risks caused by an excessively high yield-to-tensile strength ratio.
Excellent welding performance (core requirement for pipeline steel)
The low carbon equivalent design of API 5L X52 ensures excellent welding performance, which is a core requirement for large-scale construction of pipeline steels. Grade PSL2 requires a carbon equivalent (CEIIW) ≤ 0.43 and Pcm ≤ 0.25, ensuring good toughness and resistance to cold cracking in the heat-affected zone under field welding conditions.
Key Welding Points:
• Low CE value:
Effectively reduces the tendency of the welding heat-affected zone to harden and lowers the risk of cold cracks
•Low-harmful-element content:
The S content is strictly controlled at a low level to ensure the purity of the weld and base material
• Suitable for various welding methods:
butt welding of seamless steel pipes, submerged arc welding of spiral/straight seam welded pipes, etc., with good field ring welding performance
For PSL1 grade, the upper limit of carbon content is relatively wide (≤ 0.28% for seamless pipes, ≤ 0.26% for welded pipes), and preheating of 100-150°C is recommended during welding. For PSL2 grade, the carbon content requirement is stricter (≤ 0.20-0.22%), resulting in better weldability, and usually no special preheating or only lower preheating temperature is required.
Good low-temperature toughness and resistance to brittle fracture
The API 5L X52 PSL2 grade requires Charpy V-notch impact testing to ensure the material's resistance to brittle fracture under low-temperature service conditions. The fine-grained microstructure obtained through the TMCP process significantly enhances the material's low-temperature toughness, enabling X52 line pipe steel to be reliably applied in cold regions and environments with large seasonal temperature variations.
Typical impact toughness index (PSL2):
• Test temperature: Typically -20°C or lower (as per user requirements)
• Minimum impact energy:≥ 27 J (average value) / ≥ 20 J (single value)
Good corrosion resistance and environmental adaptability
API 5L X52 exhibits good resistance to uniform corrosion in normal atmospheric, fresh water, soil, and oil and gas media. For acidic service environments (containing H₂S), API 5L PSL2 Appendix J provides supplementary requirements for sour service pipes, including lower sulfur content (≤ 0.002%) and more stringent verification of HIC/SSC resistance performance.
For marine environments, PSL2 grade can be selected along with appropriate anti-corrosion coatings (such as 3PE, FBE), suitable for offshore platform structural pipes and subsea pipelines.
Good cold bending and processing performance
API 5L X52 has a lower carbon content and a moderate yield-to-tensile ratio (typically ≤ 0.93 for PSL2), which gives it good cold bending formability. It is suitable for cold-bent pipe production and can be used to manufacture hot-bent elbows through hot bending processes. It also exhibits good shearing, blanking, and roll forming properties in coil and plate conditions.
Technical Specifications
Chemical Composition(API Spec 5L / ISO 3183)
|
Element |
PSL1 Seamless Tube |
PSL1 Welded Pipe |
PSL2 |
Note |
|
C |
≤ 0.28% |
≤ 0.26% |
≤ 0.20-0.22% |
Low-carbon design to ensure weldability and low-temperature toughness |
|
Mn |
≤ 1.40% |
≤ 1.40% |
≤ 1.40% |
Solid solution strengthening, improve strength |
|
P |
≤ 0.030% |
≤ 0.030% |
≤ 0.025% |
Harmful elements, strictly controlled |
|
S |
≤ 0.030% |
≤ 0.030% |
≤ 0.015% |
Harmful elements, strictly controlled to ensure low-temperature toughness |
|
Si |
≤ 0.45% |
≤ 0.45% |
≤ 0.45% |
Deoxidizer, improve strength |
|
V |
≤ 0.05% |
≤ 0.05% |
≤ 0.10% |
Microalloying elements, precipitation strengthening |
|
Nb |
≤ 0.05% |
≤ 0.05% |
≤ 0.05% |
Microalloying elements, controlled rolling for fine grain |
|
Ti |
≤ 0.04% |
≤ 0.04% |
≤ 0.04% |
Microalloying elements, precipitation strengthening |
|
CEIIW |
- |
- |
≤ 0.43% |
Carbon equivalent, controlling weldability |
|
Pcm |
- |
- |
≤ 0.25% |
Crack Sensitivity Index |
|
Fe |
Remaining quantity(≈ 97%) |
Remaining quantity(≈ 97%) |
Remaining quantity(≈ 97%) |
Matrix element |
Physical Properties
|
Property |
Value/Range |
Test Conditions |
|
Density |
≈ 7.85 g/cm³ |
Room Temperature (20°C) |
|
Melting Point |
≈ 1420-1460°C |
--- |
|
Elastic modulus |
≈ 207 GPa |
Room Temperature |
|
Thermal Conductivity |
≈ 50 W/(m·K) |
Room Temperature |
|
Coefficient of Thermal Expansion (20-100°C) |
≈ 12.0 × 10⁻⁶ /K |
--- |
|
Poisson's ratio |
≈ 0.28 |
Room Temperature |
Mechanical Properties (Typical Value)
|
Performance |
PSL1 |
PSL2 |
Implementation standards |
|
Minimum Yield Strength |
360 MPa |
360 MPa |
API Spec 5L / ISO 3183 |
|
Maximum Yield Strength |
- |
530 MPa |
API Spec 5L / ISO 3183 |
|
Minimum Tensile Strength |
460 MPa |
460 MPa |
API Spec 5L / ISO 3183 |
|
Maximum Tensile Strength |
- |
760 MPa |
API Spec 5L / ISO 3183 |
|
Elongation |
≥ 23% |
≥ 23% |
API Spec 5L |
Note: The 'X52' in API 5L X52 indicates a minimum yield strength of 52,000 psi (approximately 360 MPa), with the number representing thousands of pounds per square inch (ksi). The actual yield strength of the pipe material typically ranges between 380-480 MPa, and the tensile strength ranges between 470-550 MPa.
Applicable Media
1. Natural gas, crude oil, and refined oil: main trunk lines and branch lines for long-distance transportation
2. Water and slurries: water pipelines, slurry transportation
3. Chemical media: fluid pipelines in chemical plants
4. Urban gas: medium and high-pressure gas networks in cities
5. Structural pipes: building structures, platform jackets (non-corrosive environments)
6. General corrosive environments:conventional soil, atmosphere, and fresh water
Note: API 5L X52 is not suitable for high-temperature, high-pressure, strongly acidic media (such as high-temperature concentrated hydrochloric acid and hydrofluoric acid). In acidic oil and gas environments containing H₂S, special grade materials specified in Appendix J of API 5L PSL2 (acid-resistant pipes) should be selected, with additional control over sulfur content, hardness, and HIC resistance performance.
Product Form and Manufacturing Process
Seamless steel pipe (Seamless)
Process: Hot Rolling Piercing + Extension Rolling
Diameter Range: 21.3 - 1067 mm (1/2" - 42")
Wall thickness range: 2 - 150 mm
Features: Seamless, high pressure-bearing capacity, suitable for high-pressure oil and gas mainlines
Typical applications: high-pressure fluid transportation, oil and gas wellhead gathering and transmission pipelines
Straight Seam High-Frequency Resistance Welded Pipe (ERW)
Process: Hot-rolled coil → Cold bending forming → High-frequency resistance welding
Outer Diameter Range: Typically ≤ 610 mm (24")
Wall thickness range: Typically ≤ 20 mm
Features: High dimensional accuracy, high production efficiency, and significant cost advantages
Typical applications: medium and low-pressure oil and gas branch lines, urban gas pipelines, and structural pipes
Welding Heat Input Control: High-frequency welding at ≥ 100 kHz (PSL2 requirement) to ensure stable weld quality
Spiral Submerged Arc Welded Pipe (SSAW)
Process: Hot-rolled coil → Spiral forming → Dual-sided submerged arc welding
Outer Diameter Range: Typically 219 - 2500 mm
Wall thickness range: 6 - 25 mm
Features: The large diameter offers significant advantages, allowing steel strips of the same width to produce various diameters. The stress of spiral welds is only 75-90% of that of straight seams, enabling them to withstand higher pressures. Theoretically, they can be continuously produced in unlimited lengths.
Typical applications: large-diameter water/gas transmission pipelines, offshore engineering jacket
Straight Seam Submerged Arc Welded Pipe (LSAW)
Process: Steel Plate → JCOE Forming / UOE Forming → Dual-Sided Submerged Arc Welding
Outer Diameter Range: 406 - 1620 mm (16" - 64")
Wall thickness range: 6 - 50 mm
Features: Short welds, low welding material consumption, wide range of outer diameter and wall thickness
Typical applications: high-pressure long-distance transmission pipelines, submarine pipelines, oil and gas gathering and transportation mainlines
Applicable Standards and Delivery Condition
Standard:API Spec 5L,ISO 3183,GB/T 9711
Product Specification Level: PSL1 (Basic Level), PSL2 (Enhanced Level)
Delivery Condition: Hot-rolled, Controlled Rolling (TMCP), Normalized, Normalized Rolling, Heat Treatment (Quenching + Tempering), etc.
End Processing: Flat Ends, Beveled Ends, Threaded Ends, Special Fitting Ends
Certificate: When complying with PSL2 requirements, a compliance certificate (SR15.1 mandatory) must be provided, and full-process traceability must be implemented (SR15.2 mandatory).
Treatment Regime and Welding Key Points
The final performance of API 5L X52 depends on the TMCP controlled rolling and controlled cooling process:
1. Controlled Rolling and Controlled Cooling (TMCP, used to obtain a fine-grained microstructure and optimal mechanical properties):
Heat to 1100-1200°C for rough rolling, then perform controlled rolling with large reduction in the 850-950°C finishing temperature range (rolling in the non-recrystallization zone), followed by controlled cooling within 600-800°C. This results in a uniform and fine ferrite + pearlite microstructure (grain size typically ≥ 9) to ensure a balanced combination of strength and toughness.
2. Post-weld Heat Treatment (if required):
If stress relief is required after pipe ring weld welding, post-weld heat treatment at 550-650°C for 1-2 hours can be performed. Post-weld heat treatment should pay attention to controlling the heating and cooling rates to avoid affecting the microstructure and properties of the base material.
Important Reminder:
In conventional oil and gas transmission environments without H₂S, stress relief heat treatment is typically not required after welding.
For pipelines in an acidic environment (containing H₂S), strict compliance with Appendix J of API 5L PSL2 is required to avoid excessive hardness caused by improper post-weld heat treatment.
During welding, strict control of heat input and interpass temperature is required to prevent grain coarsening in the heat-affected zone.
API 5L X52 (L360) is suitable for medium and high-pressure oil and gas transmission, urban pipeline networks, and structural pipe applications. It is recommended for use in the following areas:
Application Fields
-
Oil and Natural Gas Gathering and Long-Distance Transportation
● Main trunk lines and branch lines of long-distance oil and gas pipelines
● Internal oil gathering and transportation pipelines in an oil field
● Gas field raw gas gathering and transportation pipeline -
Urban gas pipeline network
● Medium and high-pressure gas transmission and distribution pipeline network
● Inlet and outlet pipelines of urban gas pressure regulating stations -
Water Conveyance and Irrigation Engineering
● Long-distance water transmission pipeline
● Complementary pipes for irrigation canals in farmland. -
Chemical Engineering and Industrial Piping
● Chemical plant process pipelines
● Power station circulating water pipe
● Industrial cooling water system -
Structural Tubing
● Building steel structure support pipe
● Offshore Platform Jacket (Non-Corrosive Areas)
● Pipes for bridge pile foundations
● Transmission line tower structural pipe
Delivery and Customization
We offer flexible and reliable supply chain solutions to ensure you receive API 5L X52 line pipe that perfectly matches your project requirements.
|
Form |
 Seamless Steel
Pipe |
 Straight Seam Resistance
Welded Pipe (ERW) |
 Spiral Submerged Arc
Welded Pipe (SSAW) |
 Straight Seam Submerged Arc
Welded Pipe (LSAW) |
|---|---|---|---|---|
|
Conventional Range |
Outer Diameter: 21.3 - 1067 mm; |
Outer Diameter: 21.3 - 610 mm; Wall Thickness: 2 - 20 mm |
Outer Diameter: 219 - 2500 mm; Wall Thickness: 6 - 25 mm |
Outer Diameter: 406 - 1620 mm; Wall Thickness: 6 - 50 mm |
|
Customization Capability |
Hot-rolled seamless pipes, fixed-length cutting, bevel machining, pipe end threads, special heat treatment conditions |
High-frequency straight-seam welded pipes, fixed-length cutting, bevel processing, galvanization/plastic coating treatment |
Large-diameter spiral welded pipes, fixed-length cutting, bevel processing, anti-corrosion coating (FBE/3PE) |
JCOE/UOE forming, length cutting, bevel machining, special pipe end treatment |
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FAQ
Q: What are the main advantages of API 5L X52?
Q: What is the difference between API 5L X52 PSL1 and PSL2? How to choose?
Q: What are the differences between API 5L X42, X52, X60, and X65? How to choose among them?
Q: What is the maximum operating temperature for API 5L X52?
Q: What is the welding performance of API 5L X52?
Q: What is the corrosion resistance of API 5L X52?
Q: Can API 5L X52 replace ASTM A53 or structural pipe?
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