Galvanic corrosion occurs when two dissimilar metals come into electrical contact with a conductive electrolyte that is usually rainwater or groundwater. If aluminum and carbon steel are connected and immersed in seawater, the aluminum is likely to corrode more quickly, whilst the steel will receive protection. This is a good example of galvanic corrosion. It is not only costly to repair, but can also cause damage that can lead to injury or even possibly death. We have guidelines on preventing galvanic corrosion:
How To Prevent Galvanic Corrosion
Galvanic corrosion can be prevented by:
Selecting Materials With Similar Corrosion Potentials
To minimize the risk of galvanic corrosion of fasteners, match the surface metal on the fastener with that on the metal it will fasten. Fasteners such as bolts and screws should be made of the metal less likely to corrode.
Insulating The Two Metals From Each Other
Metals like copper are great conductors of electricity and are prone to electrolysis and galvanic corrosion. If left unprotected, underground copper or brass lines can be rotted out by galvanic corrosion. To insulate these metals, PVC or plastic irrigation tubing can be used. Paints, coatings, oils, and greases can also be used.
Using Corrosion Inhibitors
The inhibitors that are most effective against galvanic corrosion are those that remove dissolved oxygen from the electrolyte solution. Removing oxygen reduces the possibility of reduction taking place at the anode, and as a result, this halts the galvanic process.
Other Considerations To Take Note Of When Preventing Galvanic Corrosion
Galvanic corrosion can sometimes occur without initial physical contact. Corrosion of a metal may result in water-soluble corrosion products, which can deposit on to the surface of another metal. A good way to prevent incidents like this from occurring is to ensure that the right materials are used. Also keep in mind the relative placement of a particular metal on a building. For example, one should ensure the gutters from a copper roof should always be in copper or stainless steel, but not aluminum.