Steel High Frequency Welded Spiral Fin Tube (High Frequency Welded Helical Fin Tube)
1. Basic Concept
Steel High Frequency Welded Spiral Fin Tube is a core heat transfer element used in industrial heat exchange equipment.
Its full name is Steel High Frequency Electric Resistance Welded Spiral Fin Tube.
It consists of:
- A seamless steel tube as the base pipe
- A carbon steel strip as the spiral fin
Through high-frequency electric resistance welding, the steel strip is continuously helically wound around the outer surface of the tube and metallurgically fused with the pipe wall.
This process greatly increases the external heat transfer surface area, making it highly suitable for:
- Gas-to-liquid heat exchange
- Gas-to-gas heat exchange
- Waste heat recovery systems
- Industrial heating and cooling applications
2. Structure Composition (All-Steel Construction)
Steel Base Tube (Fluid Flow Channel)
The base tube is the main pressure-bearing component where the heat transfer medium flows.
Common materials include:
- 20# seamless carbon steel pipe
- Q235B carbon steel pipe
- 16Mn low alloy steel pipe
- 304 stainless steel pipe
Typical internal heat transfer mediums:
- Hot water
- Saturated steam
- Thermal oil
- High-temperature flue gas
Pressure range:
1.6–25 MPa
Steel Spiral Fins (Extended Heat Transfer Surface)
The spiral fins are manufactured from continuous cold-rolled steel strips and are welded onto the tube surface.
There are mainly two types:
Solid Fin Type
A continuous steel strip forms a complete spiral fin.
Advantages:
- Lower airflow resistance
- Stable operation
- Suitable for clean gases and heating systems
Typical applications:
- Industrial heating
- Clean air heat exchangers
- HVAC systems
Serrated Fin Type
The fin strip is cut into segmented teeth before welding.
Advantages:
- Improves turbulence
- Enhances heat transfer efficiency
- Reduces boundary layer thickness
Typical applications:
- Boiler economizers
- Waste heat recovery systems
- High-temperature flue gas heat exchangers
Welding Joint (Core Metallurgical Bond)
The high-frequency welded joint creates a strong metallurgical connection between the fin and tube.
Features:
- No gaps
- No air layer
- Extremely low contact thermal resistance
- Strong resistance against vibration and thermal cycling
Unlike ordinary mechanically wrapped fin tubes, HF welded spiral fin tubes maintain long-term performance without fin loosening.
3. Manufacturing Process: High Frequency Resistance Welding Technology
The production process includes:
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The steel strip is continuously fed and spirally wound around the steel tube.
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A high-frequency current of approximately 200–500 kHz passes through the contact area.
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Due to the skin effect and proximity effect, heat is concentrated at the tube-fin interface.
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The contact surface rapidly reaches approximately 800–1000°C, creating a molten bonding zone.
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Pressure rollers simultaneously compress the materials, forming a solid-state metallurgical weld.
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No welding wire or flux is required.
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After cooling, the finished fin tubes can be processed with:
- Hot-dip galvanizing
- High-temperature painting
- Anti-corrosion coatings
The continuous automated production process ensures stable quality and high manufacturing efficiency.
4. Key Advantages of High Frequency Welded Spiral Fin Tubes
Excellent Heat Transfer Performance
Compared with plain tubes:
- External heat transfer area increases by 3–8 times
- Heat dissipation capacity improves by 4–7 times
- Spiral fins enhance airflow turbulence
- Thermal boundary layers are effectively reduced
Contact thermal resistance:
<0.0005 m²·K/W
The metallurgical welding structure ensures efficient heat conduction with minimal thermal loss.
Strong Welding Bond and No Fin Detachment
Advantages:
- Welding rate ≥95%
- Weld strength close to base metal strength
- Excellent resistance to thermal expansion and contraction
- Suitable for vibration environments
Unlike traditional wrapped fin tubes, high-frequency welded fin tubes do not loosen or lose heat transfer efficiency during long-term operation.
High Temperature and High Pressure Capability
Material performance:
Carbon Steel Version
- Operating temperature: ≤450°C
Stainless Steel Version
- Operating temperature: 600°C+
Suitable for:
- High-pressure steam systems
- Thermal oil heaters
- High-temperature flue gas environments
- Industrial boilers
Compact Structure and Cost Efficiency
Benefits:
- Smaller equipment size under the same heat transfer capacity
- Reduced installation space
- Moderate material cost
- Long service life after anti-corrosion treatment
Typical service life:
10–15 years
Adjustable Flow Resistance
Fin parameters can be customized according to working conditions:
- Fin height
- Fin pitch
- Fin thickness
- Fin type
Examples:
Loose fin spacing:
- Suitable for dusty flue gas
Dense fin spacing:
- Suitable for industrial heating and drying systems
5. Main Applications of Steel Spiral Fin Tubes
Industrial Heating Systems
Applications:
- Factory heating
- Greenhouse heating
- Drying rooms
- Steel fin radiators (GRD type)
Boiler Waste Heat Recovery
Used in:
- Boiler economizers
- Air preheaters
- Flue gas heat recovery units
Chemical and Power Industries
Applications:
- Process heaters
- Flue gas coolers
- Thermal oil heat exchangers
- Industrial heat recovery systems
Drying Equipment
Widely used for:
- Wood drying
- Grain drying
- Pharmaceutical drying
- Paint curing production lines
HVAC and Thermal Energy Systems
Applications:
- District heating stations
- Steam heat exchange units
- Industrial heating equipment
