ASTM A335 P9 Alloy Steel Seamless HFW Finned Tubes for Petrochemical Industrial Furnace
What is the HFW finned tubes? How did this HFW process come into being and what about advantages of this type?
*HFW finned tubes is one type of finned tubes, this type of finned tubes are commonly used in the following scenarios: radiant and convection sections of petrochemical heating furnaces, ethylene cracking furnaces, hydrogenation reactors, heat transfer fluid furnaces, and waste heat recovery systems.
*HFW (High-Frequency Welded) denotes the advanced welding process used to bond fins tightly to the base tube, ensuring superior structural integrity and thermal conductivity.
*These finned tubes are designed to maximize heat transfer efficiency in harsh petrochemical environments involving high temperatures, high pressures, and corrosive flue gases. High-frequency welding creates a uniform, high-strength weld seam that resists vibration, thermal expansion, and contraction in cyclic heating/cooling furnace conditions. The fins are not prone to loosening or detachment, ensuring reliable operation over a service life of 10–15 years under standard maintenance.
Core Characteristics of ASTM A335 P9 Seamless Steel Pipes
*Chemical Composition UNS K90941
| Carbon % | Manganese % | Phosphorus % | Sulfur % | Silicon % | Chromium % | Molybdenum % |
|---|---|---|---|---|---|---|
| 0.15max | 0.30-0.60 | 0.025 | 0.025 | 0.25-1.00 | 8.00-10.00 | 0.90-1.10 |
1.High Chromium Content (8.00%-10.00%): Forms a dense Cr₂O₃ oxide film at high temperatures, significantly enhancing resistance to high-temperature oxidation and sulfidation corrosion, making it suitable for corrosive environments containing sulfur-bearing flue gas and process gas.
2.Molybdenum Content (0.90%-1.10%): Strengthens the matrix structure, improves the material's high-temperature strength and creep resistance, and delays deformation failure during long-term high-temperature service.
3.Low Impurity Control: Ultra-low phosphorus (P≤0.025%) and sulfur (S≤0.025%) contents reduce the risk of high-temperature embrittlement and improve weldability and toughness.
*Mechanical Properties
| Tensile Strength, min | Yield Strength, min | Elongation in 2" or 50mm, min |
|---|---|---|
| 60ksi (415 MPa) | 30ksi (205 MPa) | Longitudinal:30%; Transverse:20% |
1.P9 This material has high-temperature resistance, making it suitable for high-temperature equipment such as petrochemical heating furnaces and waste heat boilers. It also has excellent creep resistance, and can operate under high temperature and pressure of 550-600℃ for a long time without the pipe wall thinning or failure due to creep, thus meeting the requirements for long-term operation of equipment.
2.P9 This material is corrosion-resistant, resisting not only high-temperature oxidation but also sulfide corrosion, making it suitable for use in heating furnaces and converters processing sulfur-containing crude oil, and protecting against corrosive media such as H₂S.However, it is not recommended for use in high-chlorine environments (such as cold and humid coastal conditions).
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