The fin is wound into a helical groove that is machined directly into the base tube wall, then the tube is rolled to close the groove. The fin foot is mechanically locked in metal-to-metal contact — the classic G-fin construction for high-temperature air coolers.
Construction
A groove of the same width as the fin foot is cut into the base tube. The aluminium fin is wound into the groove under tension and the displaced tube metal is rolled back over the fin foot. The fin is therefore held by the tube material itself, not by tension alone, which prevents the loosening that affects wrap-on fins at elevated temperature.
Product Gallery
Typical specification
| Parameter | Range |
|---|---|
| Base tube OD | 16 mm – 63 mm |
| Base tube material | Carbon steel A179 / A192 / A106, stainless steel 304 / 316L, alloy steel |
| Fin material | Aluminium 1060 / 1100, copper |
| Fin height | 8 mm – 16 mm |
| Fin pitch | 2.5 mm – 4.5 mm |
| Fin thickness | 0.3 mm – 0.6 mm |
| Working temperature | Up to 400 °C (752 °F) |
| Groove depth | 0.3 mm – 0.5 mm (wall thickness increase required) |
Advantages
- Stable performance at high metal temperatures where tension-wound fins would relax.
- Better resistance to vibration and thermal cycling than L/LL/KL types.
- Bare or coated aluminium fins give good corrosion behaviour in coastal and industrial atmospheres.
- Proven, widely accepted design for refinery and petrochemical air coolers.
Points to watch when specifying
Because a groove is cut into the tube wall, the base tube wall thickness must be increased to keep the pressure rating. We calculate the required wall for your design pressure and confirm it on the drawing before production. For corrosive tube-side duties, stainless or alloy base tubes are available with the same fin geometry.
Send your air cooler duty for a G-fin proposal
Tell us the tube diameter, fin height, fin pitch, materials and quantity — we reply with price and lead time within one working day.