Applied Fin Tubes

The G type fin is commonly known as embedded fin. The fins are manufactured from strip rolled into a taper which causes it to curl. It is then continuously helically wound into a machined groove, approximately 0.3mm (0.012") deep, into the tube wall. The fin is locked in position by backfilling of the tube material on both sides of the fin to give a firm bond. No tube material is removed. There are two methods of groove forming:

• Rolling - Used on carbon steel tubes in the hardness range 45-70 Rockwell B and thicker wall tubes (e.g.walls thicker than 13 bwg minimum wall on 1" od). A rotating profiled disc rolls a groove into the tube wall, the fin is wound into the groove, the tube material is simultaneously backfilled on each side of the fin by profiled rotating discs. Fin pull out load approximately 2-5 Kg (4-11 lb).
• Plowing - Used on all types of tube material and on thinner tube walls (e.g. 16 swg average wall on 1" od). A stationary carbide tipped tool plows a groove into the tube wall, the fin is wound into the groove, the raised tube material is simultaneously backfilled on each side of fin by flat rotating discs. Fin pull out load approximately 3-12 Kg (6-26 lb).

The L type fin is commonly known as wrap on fin. The fins are manufactured from strip which is preformed into an accurately controlled L shape rolled into a taper which causes it to curl. It is then continuously helically wound under tension onto a tube. The fin hugs the tube. Providing the correct fin strip is used the foot of one fin butts up against the next fin and there is no gap between the fins. This gives some corrosion protection to the tube. The fins are secured at each end to prevent unwinding. The most common and economic method is by stapling with galvanised or stainless steel staples. The most expensive but best method is by using cast zinc support rings. Copper fins are normally soldered to the base tube.

The LL type fin is commonly known as double L or overlapped L fin. The fins are manufactured from strip in similar to the L type except that the foot is preformed into an accurately controlled stepped double L shape, rolled into a taper which causes it to curl. It is then continuously helically wound under tension onto a tube. The fin hugs the tube with one fin overlapping the foot of the next fin with complete coverage of the base tube. This gives good corrosion protection to the tube. The fins are secured at each end in a similar way as L fin.

The KL type fin is commonly known as knurled L fin. The fins are manufactured from strip which is preformed into an accurately controlled L shape similar to the L type, rolled into a taper which causes it to curl. It is then continuously helically wound under tension onto the tube. The fin hugs the tube. The base tube is knurled by a rotating tool, then the foot of the fin is knurled into the knurling of the base tube providing a tight bond with increased thermal performance. Providing the correct fin strip is used the foot of one fin butts up against the next fin and there is no gap between the fins. This gives some corrosion protection to the tube. The fins are secured at each end to prevent unwinding in a similar way as L fins.