I. Overview of GB/T 9711 Line Pipe
GB/T 9711 steel pipe for transmission purposes is a high-performance line pipe manufactured in accordance with the Chinese National Standard GB/T 9711. It is widely utilized in long-distance transmission systems for petroleum, natural gas, and various other fluids.
In terms of technical requirements and performance specifications, this product is benchmarked against API 5L. It exhibits excellent strength, toughness, and weldability, thereby meeting operational demands under high-pressure and complex working conditions.
Depending on specific project requirements, these steel pipes are available in various Product Specification Levels (PSL), such as PSL1 and PSL2. Furthermore, they support a range of manufacturing processes—including ERW, LSAW, and SSAW—making them suitable for onshore pipelines, offshore subsea lines, and urban energy transmission projects. Consequently, they constitute one of the key materials frequently employed in international pipeline engineering.
II. Classification of GB/T 9711 Line Pipe
i. Classified by Product Grade
| Category | Description |
|---|---|
| PSL1 | Base grade, suitable for general service conditions |
| PSL2 | High grade, suitable for high-pressure, long-distance oil and gas pipelines |
ii. Classified by Production Process
| Category | Full Name | Features |
|---|---|---|
| ERW | High-Frequency Resistance Welded Pipe | Primarily small diameter, low cost, high efficiency |
| LSAW | Longitudinal Submerged Arc Welded Pipe | Large diameter, high strength, suitable for critical projects |
| SSAW | Spiral Submerged Arc Welded Pipe | Can produce extra-large diameter, cost-effective |
iii. Classified by Steel Grade (Material Strength)
| Steel Grade (GB) | Corresponding API Grade | Features |
|---|---|---|
| L245 | B | Common basic grade |
| L290 | X42 | Medium strength |
| L320 | X46 | Standard pipeline |
| L360 | X52 | Common engineering grade |
| L390 | X56 | Medium-high strength |
| L415 | X60 | High strength |
| L450 | X65 | High-end projects |
| L485 | X70 | Long-distance pipeline |
iv. Classified by Use
| Category | Application |
|---|---|
| Oil Pipeline Pipe | Crude oil transportation |
| Natural Gas Pipe | Natural gas transportation |
| Water Pipeline | Urban water supply and drainage |
| Structural Pipe | Bridges, piling, etc. |
v. Classified by surface treatment
| Category | Description |
|---|---|
| Black Pipe | Original state, no coating |
| Anti-corrosion Pipe | 3PE / FBE coating |
| Painted Pipe | Rust-proof oil or paint |
| Galvanized Pipe | Galvanized treatment (less commonly used for pipeline pipes) |
III. GB/T 9711 PSL1 vs. PSL2 Chemical Composition Comparison Table (%)
| Steel Grade | Grade | C (Carbon) | Mn (Manganese) | Si (Silicon) | P (Phosphorus) | S (Sulfur) |
|---|---|---|---|---|---|---|
| L245 | PSL1 | ≤0.28 | ≤1.20 | ≤0.45 | ≤0.035 | ≤0.035 |
| L245 | PSL2 | ≤0.28 | ≤1.20 | ≤0.45 | ≤0.030 | ≤0.030 |
| L290 | PSL1 | ≤0.28 | ≤1.30 | ≤0.45 | ≤0.035 | ≤0.035 |
| L290 | PSL2 | ≤0.28 | ≤1.30 | ≤0.45 | ≤0.030 | ≤0.030 |
| L320 | PSL1 | ≤0.28 | ≤1.40 | ≤0.45 | ≤0.035 | ≤0.035 |
| L320 | PSL2 | ≤0.28 | ≤1.40 | ≤0.45 | ≤0.030 | ≤0.030 |
| L360 | PSL1 | ≤0.28 | ≤1.40 | ≤0.45 | ≤0.035 | ≤0.035 |
| L360 | PSL2 | ≤0.28 | ≤1.40 | ≤0.45 | ≤0.030 | ≤0.030 |
| L390 | PSL1 | ≤0.26 | ≤1.50 | ≤0.45 | ≤0.030 | ≤0.030 |
| L390 | PSL2 | ≤0.26 | ≤1.50 | ≤0.45 | ≤0.025 | ≤0.025 |
| L415 | PSL1 | ≤0.24 | ≤1.60 | ≤0.45 | ≤0.030 | ≤0.030 |
| L415 | PSL2 | ≤0.24 | ≤1.60 | ≤0.45 | ≤0.025 | ≤0.025 |
| L450 | PSL1 | ≤0.22 | ≤1.60 | ≤0.45 | ≤0.030 | ≤0.030 |
| L450 | PSL2 | ≤0.22 | ≤1.60 | ≤0.45 | ≤0.025 | ≤0.025 |
| L485 | PSL1 | ≤0.22 | ≤1.70 | ≤0.45 | ≤0.030 | ≤0.030 |
| L485 | PSL2 | ≤0.22 | ≤1.70 | ≤0.45 | ≤0.025 | ≤0.025 |
IV. GB/T 9711 Mechanical Properties Table (PSL2)
| Steel Grade | Yield Strength (MPa) ≥ | Tensile Strength (MPa) ≥ | Elongation (%) ≥ |
|---|---|---|---|
| L245 | 245 | 415 | 21 |
| L290 | 290 | 415 | 21 |
| L320 | 320 | 435 | 21 |
| L360 | 360 | 460 | 21 |
| L390 | 390 | 490 | 20 |
| L415 | 415 | 520 | 20 |
| L450 | 450 | 535 | 18 |
| L485 | 485 | 570 | 18 |
V. GB/T 9711 Line Pipe: Application Fields
GB/T 9711 steel pipes for transmission are widely utilized in a diverse range of transport and engineering projects. Their primary applications encompass the following areas:
- Petroleum Pipeline Transport
Used for crude oil transmission pipelines and oilfield gathering lines.
Suitable for high-pressure, long-distance oil transport projects. - Natural Gas Pipelines
Urban gas distribution networks and long-distance natural gas trunk lines.
Capable of stable operation in low-temperature and high-pressure environments. - Water Conservancy and Urban Water Supply
Urban water supply, drainage, and water transmission projects.
Includes pipelines for potable water, industrial water, and irrigation systems. - Offshore and Coastal Engineering
Subsea oil and gas transmission pipelines.
Pipelines for offshore platforms and near-shore engineering structures. - Industrial Pipelines
Transmission pipelines for industries such as chemicals, metallurgy, and electric power.
Used for conveying liquids, gases, and other industrial media. - Structural Applications
Bridges, building pile foundations, and support structures.
Serve a dual function, combining load-bearing capacity with fluid transmission capabilities.
