API 5L X80

API 5L X80

API 5L X80 (ISO 3183 L555) is an ultra-low carbon microalloyed high-strength pipeline steel, belonging to the X80 grade under the API Spec 5L standard. It has a minimum yield strength of 80,000 psi (555 MPa) and a minimum tensile strength of 90,000 psi (625 MPa). API 5L is an internationally recognized specification for pipeline steel tubes, covering both seamless and welded steel tubes. It is suitable for pipeline systems used in the long-distance high-pressure transportation of oil, natural gas, water, and gaseous fluids.
The core feature of API 5L X80 lies in the comprehensive balance of ultra-high strength and excellent low-temperature toughness. This steel grade is produced using a thermomechanical controlled rolling (TMCP) process, combined with advanced controlled rolling and cooling technologies, which yield a uniform and fine acicular ferrite + bainite microstructure. This microstructure ensures a yield strength of 555 MPa while still maintaining excellent low-temperature toughness and weldability. X80 is one of the highest strength grades currently commercially applied in pipeline steels, representing the advanced development direction of modern pipeline steels. It is widely used in ultra-high-pressure long-distance transmission pipelines, marine pipelines, and structural pipe applications.
API 5L X80 covers two product specification levels: PSL1 and PSL2. PSL1 is the basic level with broader requirements for chemical composition and mechanical properties, suitable for conventional pipeline engineering. PSL2 is the enhanced level with stricter requirements for carbon equivalent (CE), impact toughness, non-destructive testing, and others, applicable to harsh service environments such as high pressure, low temperature, and acidic conditions. The product complies with international standards including API Spec 5L, ISO 3183, and GB/T 9711. For acidic service environments containing H₂S, PSL2 Appendix J acid-resistant pipes (X80MS / L555MS) can be selected to meet more stringent HIC/SSC requirements. The application of X80 can reduce pipe wall thickness by 10-15% and pipe weight by 15-20%, thereby significantly lowering steel consumption and welding construction costs.
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Description
Technical Parameters

Products Features

High-Temperature Oxidation Resistance

Exceptional strength matched with outstanding toughness (core advantage)

The core advantage of API 5L X80 lies in its excellent balance between ultra-high strength and superior toughness. Thanks to its ultra-low carbon micro-alloyed design (carbon content typically ≤ 0.07%) and TMCP controlled rolling and cooling process, X80 maintains a minimum yield strength of 555 MPa and a minimum tensile strength of 625 MPa while still exhibiting excellent low-temperature impact toughness (-30°C impact energy ≥ 60 J). Its yield strength is approximately 1.91 times that of X42 (290 MPa), making it one of the highest-strength grades among currently commercialized pipeline steels, suitable for high-pressure conveying applications with ultra-high pressure and large wall thickness.

Performance indicators

PSL1 Requirements

PSL2 Requirements

Minimum Yield Strength (MPa)

555

555

Maximum Yield Strength (MPa)

-

675

Minimum Tensile Strength (MPa)

625

625

Maximum Tensile Strength (MPa)

-

825

Yield ratio

-

Usually ≤ 0.93

Elongation

≥ 18%

≥ 18%

Note: PSL2 imposes limits on both maximum yield strength and maximum tensile strength (with upper limits of 675 MPa and 825 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. 

High-Temperature Corrosion Resistance

Excellent welding performance (core requirement for pipeline steel)

The ultra-low carbon equivalent design of API 5L X80 ensures excellent welding performance, which is a core requirement for large-scale construction of pipeline steels. The PSL2 grade 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 content of P and S is strictly controlled (S ≤ 0.005%) to ensure the purity of the weld and base metal

• 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 (≤ 0.22%), and preheating at 100-150°C is recommended during welding; for PSL2 grade, the carbon content requirement is stricter (≤ 0.07%), resulting in better weldability and typically no need for special preheating or only requiring a lower preheating temperature.

High Stability

Excellent low-temperature toughness and resistance to brittle fracture

The API 5L X80 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 (with grain size typically ≥ 10-11) significantly enhances the material's low-temperature toughness, enabling X80 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 -30°C or lower (as per user requirements)
• Minimum impact energy:≥ 60 J (average value) / ≥ 45 J (single value)

Good Processability

Good corrosion resistance and environmental adaptability

API 5L X80 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 acid-resistant pipes (X80MS / L555MS), including lower sulfur content (≤ 0.002%), hardness control (≤ 250 HV), and strict verification of HIC/SSC resistance performance. It should be noted that the use of X80 in acidic service is subject to certain limitations, and hardness must be strictly controlled.
For the marine environment, Appendix H and Appendix J of PSL2 provide corresponding material supplementary requirements applicable to offshore platform structural pipes and subsea pipelines.

High-Temperature Oxidation Resistance

Good cold bending and processing performance

API 5L X80 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. Its work hardening characteristics help improve strength after cold bending.

Technical Specifications

Chemical Composition(API Spec 5L / ISO 3183)

 

Element

PSL1 Seamless Tube

PSL1 Welded Pipe

PSL2

Note

C

≤ 0.22%

≤ 0.22%

≤ 0.07%

Ultra-low carbon design ensures weldability and low-temperature toughness

Mn

≤ 1.40%

≤ 1.40%

≤ 1.85%

Solid solution strengthening, improve strength

P

≤ 0.030%

≤ 0.030%

≤ 0.025%

Harmful elements, strictly controlled

S

≤ 0.030%

≤ 0.030%

≤ 0.005%

Harmful elements, strictly controlled to ensure low-temperature toughness

Si

≤ 0.45%

≤ 0.45%

≤ 0.50%

Deoxidizer, improve strength

V

≤ 0.05%

≤ 0.05%

≤ 0.10%

Microalloying elements, precipitation strengthening

Nb

≤ 0.05%

≤ 0.05%

≤ 0.06-0.08%

Microalloying elements, controlled rolling for fine grain

Ti

≤ 0.04%

≤ 0.04%

≤ 0.02-0.04%

Microalloying elements, precipitation strengthening

Cr

-

-

≤ 0.50%

Improve hardenability and corrosion resistance

Mo

-

-

≤ 0.30%

Improve hardenability and temper stability

Ni

-

-

≤ 0.30%

Improve low-temperature toughness

Cu

-

-

≤ 0.20%

Improve atmospheric corrosion resistance

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)

≈ 11.5 × 10⁻⁶ /K

---

Poisson's ratio

≈ 0.28

Room Temperature

Mechanical Properties (Typical Value)

 

Performance

PSL1

PSL2

Implementation standards

Minimum Yield Strength

555 MPa

555 MPa

API Spec 5L / ISO 3183

Maximum Yield Strength

-

675 MPa

API Spec 5L / ISO 3183

Minimum Tensile Strength

625 MPa

625 MPa

API Spec 5L / ISO 3183

Maximum Tensile Strength

-

825 MPa

API Spec 5L / ISO 3183

Elongation

≥ 18%

≥ 18%

API Spec 5L

Note: The 'X80' in API 5L X80 refers to the minimum yield strength of 80,000 psi (approximately 555 MPa), with the number representing the unit of kilopounds per square inch (ksi). The actual yield strength of the pipe material typically ranges between 560-620 MPa, and the tensile strength ranges between 640-700 MPa.

Applicable Media

 

1. Natural gas, crude oil, and refined oil: Ultra-high pressure long-distance main transmission lines

2. Water and slurries: Long-distance water pipelines, slurry transportation

3. Chemical media: High-pressure fluid pipelines in chemical plants

4. Urban gas: Urban high-pressure gas distribution networks

5. Structural pipes: Building structures, offshore platform conductor jackets (non-corrosive environments)

6. General corrosive environments: Conventional soil, atmosphere, freshwater

Note:API 5L X80 is not suitable for high-temperature, high-pressure, strongly acidic media (such as hot 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 X80MS / L555MS) should be selected. Additional controls are required for sulfur content (≤ 0.002%), hardness (≤ 250 HV), and HIC resistance. It should be noted that the use of X80 in acid-resistant service is subject to certain limitations.

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 X80 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 acicular ferrite + bainite microstructure (grain size typically ≥ 10-11), ensuring a balanced combination of strength and toughness. For sour service line pipes, TMCP is the preferred process route to avoid the precipitation of harmful phases.

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 prevent excessive hardness (≤ 250 HV) caused by improper post-weld heat treatment.

During welding, strict control of heat input (recommended 0.5-2.5 kJ/mm) and interpass temperature (typically ≤ 100°C) is required to prevent grain coarsening in the heat-affected zone and excessive hardness.

API 5L X80 (L555) is suitable for high-pressure oil and gas long-distance transmission pipelines, marine pipelines, and high-strength structural pipe applications. It is recommended for use in the following areas:

 

Application Fields

  •  

    Long-distance main transmission lines for oil and natural gas
    ● Ultra-high pressure long-distance oil and gas transmission main pipelines (national projects such as the China-Russia East Line)
    ● Submarine pipelines, marine risers
    ● Main gathering and transmission lines for large gas fields, main natural gas pipeline networks

  •  

    Urban high-pressure gas pipeline network
    ● Urban high-pressure gas transmission and distribution main pipeline network
    ● Inlet and outlet main pipelines of urban gas high-pressure pressure regulation stations

  •  

    Water Conveyance and Irrigation Engineering
    ● Long-Distance High-Pressure Water Transmission Main Pipeline
    ● Accompanying Pipelines for Large-Scale Water Conservancy Projects

  •  

    Chemical Engineering and Industrial High-Pressure Piping
    ● High-pressure process pipelines in chemical industrial parks
    ● Power station high-pressure circulating water pipe

  •  

    Structural Tubing (High Strength)
    ● Jacket for offshore platform (high-strength section)
    ● Pipes for pile foundations of large bridges
    ● Steel structural support pipes for high-rise buildings
    ● Structural pipes for offshore wind power foundations

Delivery and Customization

We offer flexible and reliable supply chain solutions to ensure you receive API 5L X80 line pipe that perfectly matches your project requirements.

Form

3001
Seamless Steel
Pipe
1001
Straight Seam Resistance
Welded Pipe (ERW)
4001
Spiral Submerged Arc
Welded Pipe (SSAW)
4001
Straight Seam Submerged Arc
Welded Pipe (LSAW)

Conventional Range

Outer Diameter: 21.3 - 1067 mm; Wall Thickness: 2 - 150 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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Own 20,000㎡ facility with 10+ automated lines (8,000+ tons/year). In-house tooling & die center enables rapid customization and effective cost control - no middleman markup.

Full Traceability

Strict Quality Control at Every Stage

Full traceability across key QC checkpoints throughout production. 100% compliant with ASTM/ASME, EN, and GB standards. Material test reports available with every shipment.

Professional Logistics & Packaging

Reliable Delivery & Export Packaging

10+ years exporting to Europe, North America, Southeast Asia & Middle East with waterproof and anti-rust protection, combined with flexible shipping options ensures safe and on-time arrival.

Complete Export Documentation

Sample Validation Before Mass Production

We provide free samples for quality verification, allowing you to place bulk orders only after approval. We ensure consistency from sample to mass production by accurate dimensional measurement and transparent manufacturing.

FAQ

Q: What are the main advantages of API 5L X80?

 

Q: What are the differences between API 5L X80 PSL1 and PSL2? How to choose between them?

 

Q: What are the differences between API 5L X42, X60, X70, and X80? How to choose among them?

 

Q: What is the maximum operating temperature for API 5L X80?

 

Q: What is the corrosion resistance of API 5L X80?

 

Q: Can API 5L X80 replace ASTM A53 or X70?

 

 

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