Definition - What does Waterline Corrosion mean?
Waterline corrosion is a type of oxidation process that can happen to materials in contact with water. Waterline corrosion occurs when one portion of a base material is submersed in the water and another portion is in contact with the air. This creates a differential of the amount of oxygen in contact with the material's surface above and below the waterline and results in a corrosive reaction.
Corrosionpedia explains Waterline Corrosion
Waterline corrosion occurs because of the differential in oxygen concentration between the atmosphere and the water. This happens because the portion of the substrate exposed to higher amounts of oxygen (the area exposed to air) becomes a cathode, while the portion of the substrate exposed to less oxygen (the area in contact with water) becomes an anode. The creation of an anode and a cathode allows oxidation to occur. This ultimately causes the area of the substrate submersed in water to become oxidized and corrode.
Waterline corrosion is a concern in several different industries. Tanks that are used to store liquids such as water are often prone to waterline corrosion. Marine structures can also fall victim to waterline corrosion; this can lead to a complete structural failure. Ships that are left in the water for extended periods of time can be at risk of waterline corrosion as well.
Waterline corrosion can be combated by several different methods. One way is to coat the material being placed in the water. The coating keeps oxygen exposure across the substrate to a uniform amount and to a minimum. Another method is to use materials that are not as prone to oxidation as steel. Stainless steels and aluminum may be better alternatives to deter waterline corrosion.