The core characteristic of high-frequency welded finned tubes lies in their unique high-frequency induction welding process. High-frequency current instantly melts and fuses the fins to the base tube, forming a metallurgical-grade weld with a minimal heat-affected zone, ensuring high welding strength and low thermal resistance.
Their heat transfer efficiency is significantly superior to traditional finned tubes, with a heat dissipation area that can be expanded by 6-12 times, and a heat dissipation capacity of 300-1200W per meter, with a stable thermal efficiency of over 92%.
High-frequency welded finned tubes possess advantages such as high strength, corrosion resistance, and long service life, making them suitable for various applications including industrial heat exchange, HVAC, and waste heat recovery.
I. Structural Characteristics of High-Frequency Welded Finned Tubes
Metallurgical Bonding Process:
High-frequency current generates a strong magnetic field through an induction coil, causing the contact point between the base tube and the fins to instantly reach a molten state. Under pressure, a tight weld is formed, with a heat-affected zone of only 0.1-0.3mm, preventing problems such as grain coarsening and reduced toughness in steel materials due to high temperatures.
Material Selection:
The base tube uses seamless steel pipes or straight-seam welded pipes, and the fins are mostly made of low-carbon steel strips. The metallurgical bonding of the two is achieved through the high-frequency induction welding process.
Fin Design:
The fins are mostly spirally wound or longitudinally arranged. The spacing of spiral fins is typically 5-15mm, and the height of longitudinal fins can reach 20mm, allowing for a 6-12 times increase in heat dissipation area within a limited space.
II. Performance Advantages of High-Frequency Welded Finned Tubes
High Strength and Pressure Resistance: The tensile strength of the steel material itself is over 345MPa. After high-frequency welding, the tensile strength of the weld is equal to that of the base tube, and the overall structure can withstand pressures of 1.6-10MPa, making it suitable for high-pressure conditions such as industrial steam (pressure typically 0.8-4MPa) and high-temperature hot water (1.0-2.5MPa). Excellent Thermal Conductivity and Heat Dissipation Efficiency:
The thermal conductivity of steel is approximately 45 W/(m·K), which is lower than that of aluminum. However, the metallurgical bonding structure of high-frequency welding reduces the contact thermal resistance to below 0.0005 m²·K/W, allowing heat to be quickly transferred from the base tube to the fins.
Under the same operating conditions (heat medium temperature 120℃, ambient temperature 20℃), a Φ57×3mm steel finned tube (fin height 12mm, spacing 8mm) can dissipate up to 280 W/m of heat, more than four times that of a standard steel pipe of the same specifications.
Strong Corrosion Resistance and Long Service Life:
Through anti-corrosion treatments such as hot-dip galvanizing, epoxy powder coating, and fluorocarbon coating, steel finned tubes can resist corrosion from humid, dusty, and mildly acidic or alkaline environments.
When the hot-dip galvanized layer thickness reaches 85μm or more, the service life in humid industrial plant environments can reach 15-20 years, which is 3-4 times longer than that of untreated steel pipes; in central heating systems, the steel base tube with inner wall passivation treatment can also prevent water oxidation corrosion.
Cost and Maintenance Economy:
The price of low-carbon steel raw materials is only 1/3 of stainless steel and 1/5 of copper, and the high-frequency welding process is highly automated (production line speed reaches 15-20 m/min), significantly reducing manufacturing costs, making it 20%-25% cheaper than brazed steel finned tubes.
In daily maintenance, steel fins are not easily deformed and dust is easy to clean. Only 1-2 times of compressed air blowing per year is required, and the maintenance cost is less than half of that of aluminum finned tubes.
III. Applications of High-Frequency Welded Finned Tubes
High-frequency welded finned tubes for waste heat recovery systems:
In the flue gas duct at the end of a power plant boiler, an air preheater composed of Φ42×3mm steel finned tubes can reduce the flue gas temperature from 180℃ to below 120℃, achieving a waste heat recovery rate of 35%, saving more than 5000 tons of standard coal per year for a single 300MW unit. High-Frequency Welded Finned Tubes for Refineries:
Used in oil slurry heat exchangers for catalytic cracking units, these tubes withstand high-temperature oil up to 350℃, achieving efficient heat exchange.
High-Frequency Welded Finned Tubes for Central Heating Systems:
Widely used in radiators assembled with Φ32×2.5mm steel finned tubes, the modular design allows for flexible assembly according to different room layouts. In northern residential buildings, each radiator unit (10 tube rows) provides a heat output of 1800W at a supply/return water temperature of 75℃/60℃, meeting the heating needs of a 15-20㎡ room.
High-Frequency Welded Finned Tubes for Agricultural Greenhouses:
Due to their low-temperature resistance (-30℃ without cracking) and anti-aging properties, they are a preferred choice for winter heating, maintaining an indoor temperature of 15-25℃ to ensure crop growth.
High-frequency welded finned tubes are highly favored for their efficient heat transfer, robust structure, and energy-saving durability, and are widely used in greenhouses, industrial waste heat recovery, and power plant air cooling systems.