ASTM A179 KL Type Finned Tube with Al1060 Fins For Power Plant Air Cooling Systems Overview ASME SA179 KL type finned tube with Al1060 fins is a high-efficiency mechanical wound heat exchange tube widely adopted in industrial air coolers, heat exchangers, waste heat recovery systems and HVAC thermal equipment. Different from ordinary standard fin tubes, the KL-type structure adopts a knurled tube surface combined with L-foot tension winding technology, which perfectly solves