Galvanic Corrosion or two-metal corrosion must have two conditions present to occur. There must be two dissimilar metals in close proximity of each other, and a conducting fluid like salt spray, acid rain, or chemically tainted rainwater that bridges the two metals. From there, the two metals act as a battery where one metal sacrifices itself to the other. The more dissimilar the metals (like copper and aluminum), the greater the potential for corrosion.

American Standard's Spine Fin™ coil utilizes two similar metals Aluminum 7072 for the fin stock and aluminum 3102 for the tube. A copper tube/aluminum fin plate fin coil has 5 times more corrosion potential than the all aluminum Spine Fin™ coil. This helps American Standard's Allegiance® Air Conditioners and Heritage™ Heat Pumps retain their efficiency.

In the construction of plate fin coils, aluminum fin sheets are stacked on parallel rows of copper tubes. The copper tubes are then mechanically expanded to make contact with the fin sheets. After a few months or years of use, a tiny gap develops between the tube and tin sheet because the two metals expand and contract at different rates. As moisture enters this tiny crevice, corrosion begins and thermal contact is diminished or lost entirely as the aluminum fin sheet deteriorates from Galvanic corrosion. As thermal contact is lost, the air conditioner or heat pump's capacity degrades below its published rating.

American Standard's Spine Fin™ is manufactured on patented high-speed machines that cut, form, and wrap aluminum fin stock around aluminum tubing. The tubing is coated with an adhesive and then tension rollers wrap the cut fin stock around the tube. A seam of the adhesive extrudes between the fin wraps. The adhesive not only locks the fin stock on the tube, but the extruded seam actually forms a barrier against capillary attraction minimizing crevice corrosion. By sealing moisture and contaminants out, thermal contact is maintained and efficiency and capacity does riot degrade nearly as much as with plate fin.