Abstract: In a finned tube product of the type having a flat thin fin wound helically on a heat exchange tube, wherein the fin is made from a material having a relatively higher coefficient of thermal expansion than the material of the tube, the improvement which comprises winding a wire helically on the surface of the tube in side by side relation with the fin and simultaneously with the winding of the fin on the surface of the tube such that each winding of wire is snuggly received between adjacent windings of fin, the wire being made of a material having essentially the same or smaller coefficient of thermal expansion as compared to the material of the tube and the longitudinal dimension of thickness of wire representing the desired spacing between adjacent windings of fin on the tube.