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High-pressure boiler tubes made according to GB 5310 standards, such as the 20MnG type, are widely used in industries that require reliable performance under extreme conditions. These tubes are specifically designed to withstand high-pressure environments in steam boilers and other critical applications.
**Quick Details:**
- **Standard:** GB 5310
- **Manufacturing Process:** Seamless, available in both hot-finished and cold-finished options.
- **Wall Thickness (WT):** Ranges from 2.8 mm to 150 mm.
- **Outer Diameter (OD):** Available from 23 mm to 1500 mm.
- **Length:** Standard lengths include 6 meters or customized lengths as per client specifications.
- **Ends:** Plain ends, beveled ends, or threaded ends depending on requirements.
The GB 5310 standard specifies the production of seamless steel tubes and pipes for high-pressure boilers. It ensures the quality and reliability needed for steam boilers and pipelines in high-pressure systems. The 20MnG grade is particularly valued for its strength and durability.
**Manufacturing Methods:**
- **Steel Smelting Method:** The steel is produced using advanced methods such as electric furnaces combined with refining processes, oxygen converters with additional refining, or electroslag remelting techniques to ensure purity and consistency.
- **Tube Blank Production:** Tube blanks can be created through continuous casting, die casting, or hot rolling (forging), ensuring uniformity and strength.
- **Steel Tube Manufacturing:** The final product is manufactured via hot rolling (extrusion or expansion) or cold drawing (rolling), providing precise dimensions and structural integrity.
- **Codenaming:** Hot-rolled tubes are designated as WH, while cold-drawn tubes are labeled as WC.
**Chemical Composition (in %):**
Below are the chemical compositions of different grades under GB 5310-2008:
| Steel Grade | C | Si | Mn | P | S | Cr | Mo | Cu | Ni | V |
|-------------|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|
| 20G | 0.17-0.24 | 0.17-0.37 | 0.35-0.65 | ≤0.030 | ≤0.030 | ≤0.25 | ≤0.15 | ≤0.20 | ≤0.25 | ≤0.08 |
| 20MnG | 0.17-0.24 | 0.17-0.37 | 0.70-1.00 | ≤0.030 | ≤0.030 | ≤0.25 | ≤0.15 | ≤0.20 | ≤0.25 | ≤0.08 |
| 25MnG | 0.18-0.24 | 0.17-0.37 | 0.80-1.10 | ≤0.030 | ≤0.030 | ≤0.25 | ≤0.15 | ≤0.20 | ≤0.25 | ≤0.08 |
| 15CrMo | 0.12-0.18 | 0.17-0.37 | 0.40-0.70 | ≤0.030 | ≤0.030 | 0.80-1.10 | 0.40-0.55 | ≤0.20 | ≤0.30 | - |
| 12Cr2MoG | 0.08-0.15 | ≤0.50 | 0.40-0.70 | ≤0.030 | ≤0.030 | 2.00-2.50 | 0.90-1.20 | ≤0.20 | ≤0.30 | - |
| 12Cr1MoV | 0.08-0.15 | 0.17-0.37 | 0.40-0.70 | ≤0.030 | ≤0.030 | 0.90-1.20 | 0.25-0.35 | ≤0.20 | ≤0.30 | 0.15-0.30 |
| 12Cr2MoWVTiB | 0.08-0.15 | 0.45-0.75 | 0.45-0.65 | ≤0.030 | ≤0.030 | 1.60-2.10 | 0.50-0.65 | ≤0.20 | ≤0.30 | 0.28-0.42 |
| 10Cr9Mo1VNb | 0.08-0.12 | 0.20-0.50 | 0.30-0.60 | ≤0.020 | ≤0.010 | 8.00-9.50 | 0.85-1.05 | ≤0.20 | ≤0.40 | 0.18-0.25 |
**Mechanical Properties:**
Here are the mechanical properties of various grades under GB 5310-2008:
| Steel Grade | Yield Strength (MPa) | Tensile Strength (MPa) | Elongation (%) |
|-------------|----------------------|------------------------|----------------|
| 20G | 410-550 | ≥245 | 24 |
| 20MnG | ≥415 | ≥240 | 22 |
| 25MnG | ≥485 | ≥275 | 20 |
| 15CrMo | 450-600 | ≥270 | 22 |
| 12CrMoG | 410-560 | ≥205 | 21 |
| 12Cr2MoG | 450-600 | ≥280 | 20 |
| 12Cr1MoVG | 470-640 | ≥255 | 21 |
| 12Cr2MoWVTiB| 540-735 | ≥345 | 18 |
| 10Cr9Mo1VNb | ≥585 | ≥415 | ≥20 |
These tubes are extensively used in power plants, refineries, and other industrial sectors where high-pressure and temperature resistance are essential. Their superior mechanical properties and chemical composition make them ideal for demanding applications.