ASTM A106 Gr B High Frequency Welded Fin Tube For Heat Exchanger

1. ASTM A106 Gr.B Fin Tube Mechanical & Material Properties

• Base Material (ASTM A106 Gr B):

Tensile Strength: 415 MPa (60,200 psi) minimum

Yield Strength: 240 MPa (35,000 psi) minimum

Elongation: ≥ 21%

Carbon Content: 0.30% max

Operating Temperature Range: -29°C to 425°C (-20°F to 800°F)

• Weld Strength:

HFW creates a metallurgical bond between fin and tube

Weld penetration: Typically 85-95% of fin thickness

Pull strength: ≥ 80 MPa (11,600 psi) fin-to-tube bond

Thermal conductivity: Enhanced 5-10x compared to bare tube

2. ASTM A106 GR.B Fin Tube Manufacturing Process

1. Tube Preparation: ASTM A106 Gr B tubes are cleaned and inspected
2. Fin Strip Feeding: Carbon steel strip is fed at controlled angle
3. High-Frequency Welding: HF current (100-800 kHz) induces localized heating at fin-tube contact point. Pressure rollers forge the heated materials together. Creates solid-state weld without filler material.
4. Fin Formation: Simultaneous spiral winding during welding
5. Post-Weld Treatment: Air cooling, potential annealing for stress relief
6. Finishing: Straightening, cutting to length, surface treatment (galvanizing/painting if specified)
7. Testing: Hydrostatic, eddy current, visual, and bond strength tests

3. ASTM A106 GR.B Fin Tube Applications

• Heat Recovery Steam Generators (HRSG) in power plants
• Air-Cooled Heat Exchangers (ACHEs) in refineries and petrochemical plants
• Fired Heaters and process heaters
• Waste Heat Recovery Systems
• Economizers and superheaters
• HVAC and industrial drying systems

4. ASTM A106 GR.B Fin Tube Advantages:

Enhanced Heat Transfer: 5-10x improvement over bare tubes

Strong Metallurgical Bond: Resists vibration and thermal cycling

Material Efficiency: Less steel required for equivalent heat transfer

Design Flexibility: Various fin densities and heights available

Proven Reliability: Extensive industry track record

5. Frequently Asked Questions

Q1: How does HFW compare to L-foot or embedded fins?
A: HFW provides superior thermal conductivity (direct metal-to-metal bond) and better mechanical strength than mechanical attachments.

Q2: What are temperature limitations?
A: Base material limits to 425°C; fin efficiency decreases above 650°C due to oxidation and thermal stress.

Q3: Can these tubes handle thermal cycling?
A: Yes, the metallurgical bond resists thermal fatigue better than mechanically attached fins.

Q4: What coatings are recommended for corrosive environments?
A: Hot-dip galvanizing, aluminizing, or specialized high-temperature paints.