(Courtesy of Kingston Technical Software)
Galvanic corrosion is the most frequent cause of unexpected corrosion failures in seawater. It has caused failures of ship fittings and deckhouse structures, fasteners, hull plating, propellers, shafts, valves, condensers, and piping. In sea atmospheres, galvanic corrosion causes failures of roofing, gutters, and car trim. The reason that galvanic corrosion causes so many failures is that it can occur any time that two different metals are in electrical contact in seawater. Since most structures and devices are made of more than one kind of metal, this diversity of materials is common and frequently overlooked in corrosion prevention activities.