ASME SA210 Gr. C KL Finned Tube with Al1060 Fins For Boiler Economizer Bundles Overview ASME SA210 GR.C KL type finned tube fitted with Al1060 fins is a robust mechanically tension-wound heat transfer component, widely deployed in boiler heat surfaces, high-pressure waste heat recovery units, process air coolers and high-temperature industrial heat exchangers. Unlike conventional L-type wound fin tubes, this KL variant adopts tube knurling paired with L-foot tension wrapping