Different types of helical high finned tubes

Helical high finned tubes are specially manufactured to repair air-cooled heat exchangers. Many tube suppliers have the facilities to produce helical high finned tubes, but few offer more expertise than the team at USEL Tubular Division.

5 types of helical high finned tubes


  • Extruded fin tubes


Helical high finned tubes, formed by a bi-metallic tube and an inner tube of almost any material, are known as extruded fin tubes. This type of finned tube is hardened in the extrusion process and provides complete protection to the base of the tube. 

Extruded fins are used in water coolers, air coolers, heat exchangers, boilers and burners.


  • Wrapped fin tubes (L fin)


Wrapped helical high finned tubes, also known as L fins, rely on surface contact between the fin and tube to maximise heat transfer. The foot of the L fin enhances the corrosion protection of the base – making it ideal for moderate temperature cooling applications (temperatures up to 120°C).

L fin tubes are used in air coolers in petrochemical and power plants, as well as air heaters in food processing equipment.


  • Overlapped fin tubes (LL fin)


Overlapped fin tubes are manufactured in a similar way to the wrapped tubes, only the fin foot is completely overlapped and secured at each end to enclose the base of the tube. The LL fin offers high atmospheric corrosion resistance and is usually supplied in aluminium or copper.

Overlapped fins are suitable for temperatures up to 180°C – making them a cost-efficient alternative to extruded fins in corrosive environments.


  • Embedded fin tubes (G fin)


Unlike other finned tubes, the embedded fin tubes have a fin strip that’s cut into a groove and securely locked into place by backfilling the base tube and has a maximum working temperature of 450°C.

Aluminium embedded fins are ideal for refineries, petrochemical and gas plants. They are typically used in higher temperature applications, such as air cooling, heat exchangers, gas compressors and blast furnaces.


  • Knurled L fin tubes (KL fin)


Similar to the L fins, the KL fin tubes are knurled before the fin foot is applied. The fin foot is knurled again after application to strengthen the bond between the fin and tube – thereby improving heat transfer and providing good surface protection.

Knurled helical high fins are the preferred choice of chemical and petrochemical industries – ideal for steel mills, gas compression facilities, incinerators, food processing plants and refrigeration technology.

If you’d like to know more about helical high finned tubes, don’t hesitate to get in touch with USEL Tubular Division. They can also share their expertise to guide and advise you if you’re unsure which suits your industry best. Call 0191 587 1777 or email tubesales@usel.uk.com today.