API 5L Grade X42-X80 Pipeline Tubes for Oil & Gas Transmission Specification Compliant with API 5L (45th Edition)

API 5L Carbon Steel Pipe Performance Characteristics and Applications

1. Performance Characteristics

1.1 Chemical Composition and Material Properties
API 5L carbon steel pipe is mainly made of carbon steel or low-alloy steel, with carbon content controlled below 0.22%, and micro-alloying treatment with the addition of manganese, niobium, vanadium, and other elements.

By strictly controlling the content of impurities such as sulfur and phosphorus (≤0.025%), the material is ensured to have good low-temperature toughness.

1.2 Mechanical Properties
It has an excellent balance of strength and toughness. Typical steel grades such as L245 (GR.B) have a yield strength ≥245MPa and a tensile strength of 415-655MPa.

The elongation is not less than 23%, and the Charpy impact energy maintains a good value even at -30℃.

1.3 Processing Performance
High-frequency resistance welding (ERW) or submerged arc welding (SAW) processes are used, and the weld seam undergoes 100% ultrasonic testing and X-ray inspection.

1. Thermomechanical Processing (TMCP): The grain size is refined to 5-10 μm, significantly improving the material’s toughness.

2. Main Applications:
2.1 Oil and Gas Transportation:As a primary pipe material for long-distance oil and gas transmission trunk lines, it is widely used in major national pipeline projects such as the West-East Gas Pipeline and the China-Russia East Route Gas Pipeline.

It can withstand high-pressure transmission requirements exceeding 10 MPa, with working pressures up to 12 MPa.

2.2 Urban Pipeline Construction: Used in urban gas distribution networks, it has a smaller ellipticity deviation (≤0.6%) compared to spiral welded pipes, supporting high-precision docking construction.

In high-pressure urban pipeline networks, it can save 15%-20% in costs compared to seamless steel pipes.

2.3 Special Environment Applications:Through special processing, it can be applied in high-altitude and cold regions (such as the Tibet LNG project) and marine environments (such as the South China Sea gas field development).

It exhibits good environmental adaptability in permafrost zones and marine environments.

3. Application Advantages
It boasts a significant life-cycle cost advantage. Although the unit price is higher, its service life is extended by more than 50%, resulting in a substantial decrease in overall cost over a 20-year operating cycle.

With advancements in welding technology, large-diameter welded pipes offer clear advantages in cost and application flexibility, making them the mainstream choice in the pipeline industry.