longitudinal fin, in the form of a U-shaped fin channel, is resistance welded along the tube's longitudinal axis. longitudinal fin tubes are produced by resistance welding fins in the longitudinal direction along the length of the tube.  The fin strip is first formed into a U-shaped channel, such that each leg of the U will form a fin.  The channels are cut to the appropriate length and then oriented along the length of the tubes (pipes) and resistance welded in place.  The channels are welded in pairs

Tube Sizes:	¾" O.D. to 12" NPS (12.75" O.D.)
Fin Heights:	.21" to 1 ½"
Fin Thicknesses:	20 ga. (.035") to 18 ga. (.050")
Material:	Brass, Mild steel, stainless steel, and nickel alloys.