GB/T 9948 Seamless Steel Tubes For Petroleum Cracking
Material Specification
GB/T 9948 is a Chinese standard that specifies the requirements for seamless steel tubes used in petroleum cracking. These tubes are essential components in the petrochemical industry, where they are subjected to high temperatures and pressures. The standard ensures that the tubes have the necessary mechanical and chemical properties to withstand these harsh conditions.
Key Features
High Temperature Resistance: Designed to perform under extreme temperatures, making them suitable for high-temperature applications in petroleum refineries.
Corrosion Resistance: The chemical composition of the steel provides excellent resistance to corrosion, which is critical in environments where the tubes are exposed to various chemicals.
Durability: The seamless construction of the tubes ensures high durability and reliability, reducing the risk of failure during operation.
Versatility: Suitable for a wide range of applications within the petrochemical industry, including cracking furnaces and reformers.
Chemical Composition
| Element | Composition (%) |
| Carbon (C) | 0.15 - 0.20 |
| Silicon (Si) | 0.20 - 0.35 |
| Manganese (Mn) | 0.40 - 0.70 |
| Phosphorus (P) | ≤ 0.035 |
| Sulfur (S) | ≤ 0.035 |
| Chromium (Cr) | 0.80 - 1.10 |
| Molybdenum (Mo) | 0.15 - 0.25 |
Mechanical Properties
| Property | Value |
| Tensile Strength (MPa) | ≥ 485 |
| Yield Strength (MPa) | ≥ 275 |
| Elongation (%) | ≥ 21 |
| Hardness (HB) | ≤ 156 |
Physical Properties
| Property | Value |
| Density (g/cm³) | 7.85 |
| Thermal Conductivity (W/m·K) | 46.0 |
| Specific Heat Capacity (J/kg·K) | 460 |
Process Performance
| Process | Performance |
| Welding | Good |
| Machining | Moderate |
| Forming | Excellent |
| Heat Treatment | Applicable |
Steel Grade
The steel grades specified under GB/T 9948 include a range of carbon and alloy steels. These grades are designed to meet the specific requirements of high-temperature and high-pressure applications in the petrochemical industry. The standard provides guidelines on the chemical composition and mechanical properties for each grade, ensuring that they deliver optimal performance in their intended applications.
Application
GB/T 9948 seamless steel tubes are primarily used in the petrochemical industry for:
Cracking Furnaces: Where hydrocarbons are broken down into simpler molecules.
Reformers: Used in the production of hydrogen and other chemicals.
Heat Exchangers: For efficient heat transfer in various processes.
Pipelines: Transporting high-temperature fluids within refineries.
Possible Alternative Grades
While GB/T 9948 is a widely used standard in China, there are alternative international standards that may be considered depending on specific requirements:
ASTM A335: Specification for seamless ferritic alloy-steel pipe for high-temperature service.
EN 10216-2: European standard for seamless steel tubes for pressure purposes.
JIS G3458: Japanese standard for alloy steel pipes for high-temperature service.
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