API 5L X70 PSL2 is a specification for high-strength, welded or seamless steel pipes used in the transportation of oil, gas, and water in pipeline systems. The API 5L standard covers two levels of product specifications: PSL1 (Product Specification Level 1) and PSL2 (Product Specification Level 2). PSL2 has stricter quality control and additional mechanical and chemical requirements compared to PSL1.

API 5L X70 PSL2 Specification Overview:

1. Chemical Composition (Typical for PSL2)

PSL2 has stricter requirements for the chemical composition of steel, which ensures better control over impurities and elements such as sulfur and phosphorus.

2. Mechanical Properties

• Yield Strength: 485 MPa (70,300 psi) minimum
• Tensile Strength: 570-700 MPa (82,700 - 101,500 psi)
• Elongation: Depending on pipe dimensions, generally around 18-22%
• Impact Toughness: PSL2 requires Charpy V-Notch impact testing, especially for low-temperature performance.

3. Pipe Dimensions

• Outer Diameter (OD): Typically from 21.3 mm to 1422 mm (1/2 inch to 56 inches)
• Wall Thickness (WT): Various thicknesses, depending on the application and design requirements

4. Delivery Condition

PSL2 pipes are delivered in controlled rolled, normalized, or quenched and tempered conditions to meet specific mechanical property requirements.

5. Testing Requirements

PSL2 requires stricter and more comprehensive testing compared to PSL1, including:

• Charpy V-notch Impact Test: Required for toughness and resistance to brittle fracture at low temperatures.
• Non-destructive Testing (NDT): Such as ultrasonic or radiographic inspection for weld seams and defects.
• Hydrostatic Testing: Required to ensure the pipe can withstand the design pressure without leaks.
• Tensile Tests: Ensuring the pipe meets yield and tensile strength requirements.

6. Applications

• API 5L X70 PSL2 is commonly used for high-pressure pipelines, long-distance oil and gas pipelines, and pipeline systems in harsh environments, such as:
  • Offshore and onshore gas and oil transmission
  • Sour service applications where resistance to hydrogen sulfide (H₂S) is required
  • Subsea pipelines
  • High-strength pipelines with resistance to extreme weather conditions

7. Traceability

PSL2 pipes require full traceability from raw materials to final production. This ensures high quality and compliance with strict regulations for safety and performance.

8. Manufacturing Process

Pipes under PSL2 are manufactured using specific methods such as:

• Seamless or welded manufacturing, depending on requirements.
• Heat treatment processes like normalizing or quenching and tempering to achieve the necessary mechanical properties.

Summary Table

Conclusion:

API 5L X70 PSL2 is a high-strength pipe specification used in demanding pipeline applications where toughness, durability, and resistance to extreme conditions are required. It offers superior performance compared to PSL1 due to its stricter chemical composition, mechanical properties, and testing requirements.