During the finning operation the inside diameter of the base tubes is reduced and simultaneously helical fins are rolled out of the tube wall. Therefore the outside diameter of the fins becomes smaller or at least not larger than the permissible outside diameter of the unfinned tube sections. It is an advantage of the finning procedure that the finning operation can be interrupted at any point of the tube. The unfinned tube sections make it possible to support and fit these finned tubes in shell-and-tube heat exchangers in the same way as plain tubes.

In comparison to Trufin^® S/T Finned Tubes, Trufin^® S/TT (Turbo-Chil^®) High Performance Finned Tubes have in addition helical inside ridges which provoke an increase of the flow turbulence on the inside fluid resulting in a considerable performance increase.