ASME SA249 Stainless Steel Wound Fin Tube Fin Type L
What are finned tubes used for?
Finned tubes are the main components of heat exchangers. They are a series of tubes where fins have been added on the outside to increase the contact area with the outside fluid, to exchange heat and between the fluid inside the tube and the fluid outside the tube. Finned tubes are elongated aluminium cladded carbon steel flat tubes with brazed aluminium fins.
The metal strip (aluminum, copper or stainless steel) is fixed to the outer surface of the base tube by winding, welding or inlaying. Its main function is to increase the heat exchange area and improve the heat transfer efficiency on the air side.
The fin strip is wound at a specific angle (such as a helical angle of 30°~60°) to form a continuous spiral fin, which may be marked as "Type L".
The root of the fin is "L" shaped and fixed to the base tube by mechanical locking or welding to enhance the contact strength between the fin and the base tube and prevent loosening.
The core advantage may be anti-vibration performance or special heat transfer structure. In the petrochemical industry, such fin tubes are often used in air coolers, waste heat recovery and other scenarios, and need to be selected based on medium characteristics (temperature, corrosiveness), environmental conditions (wind speed, dust) and cost factors.
Core advantages
Efficient heat transfer: The expanded surface area of the fin can reach 10~30 times that of the base tube, significantly improving the heat transfer efficiency on the air side.
Corrosion resistance: If aluminum fins + carbon steel base tubes (Al-Fe bimetallic) are used, it has both cost advantages and atmospheric corrosion resistance.
Mechanical strength: The L-shaped root design or welding process ensures that the fins are not easy to fall off in high-speed airflow.
Economical: Lower cost than rolled fin tube (Embedded Fin), suitable for large-scale application.
SS304 Chemical Compositions
| Element |
% Present |
| Carbon (C) |
0.07 |
| Chromium (Cr) |
17.50 - 19.50 |
| Manganese (Mn) |
2.00 |
| Silicon (Si) |
1.00 |
| Phosphorous (P) |
0.045 |
| Sulphur (S) |
0.015b) |
| Nickel (Ni) |
8.00 - 10.50 |
| Nitrogen (N) |
0.10 |
| Iron (Fe) |
Balance |
SS304 Mechanical Properties
| Property |
Value |
| Comprehensive Strength |
210 MPa |
| Proof Stress |
210 Min MPa |
| Tensile Strength |
520 - 720 MPa |
| Elongation |
45 Min% |
Application
Air Cooler:
Used to cool high-temperature oil and gas (such as catalytic cracking unit outlet gas), light hydrocarbon condensation (such as LPG recovery).
Example: Wound Fin Tube is commonly used in API 661 standard air cooler, and the fin type is selected according to the medium temperature (such as stainless steel fin for high temperature).
Waste Heat Recovery System:
To recover heat in flue gas waste heat boiler, the fin material needs to be resistant to high temperature oxidation (such as 409 stainless steel).
Refrigeration Equipment:
External fin tubes of ammonia or Freon condensers, aluminum fins can reduce weight and prevent corrosion.
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