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06/01/2022
Prevention | Maintenance & Technology
Galvanic Corrosion
The Galvanic Series and what it means for you. - What you may or may not know is that not all metals are compatible. Metals find their place on a chart called the ‘Galvanic Series’ or ‘Electro-potential Series’ which outlines them from most noble to least noble.
When using two metals together, such as when stainless steel stanchions are installed, you need to ensure the screws/bolts used to secure them are compatible with the stainless. If they are not compatible, the chance of suffering galvanic corrosion becomes very real. Galvanic corrosion occurs when metals are incorrectly combined and exposed to water and other electrolytes. In this scenario the metal with a lesser nobility will become susceptible to corrosion. For harsh settings, like the humid or salt filled air around the ocean, it is suggested that metals used together do not have a greater difference that 0.15-0.2 volts on the anodic index. In standard environments like homes, the general rule is a difference no greater than 0.25 volts. If the difference between the metals is greater than these voltages the less noble metal will suffer galvanic corrosion.
Despite these rules to prevent corrosion, if two metals are not compatible they are still able to be used together provided adequate protection is in place. The protection can be achieved through methods such as sealing to make the metal watertight, electronically insulating the components from each other, sacrificial anode coating to the cathodic element which has a similar potential to the anodic area, or by developing resistance through coating, plating and other methods which increase electrical circuit protection. Either way, it’s best to have an expert confirm whether the protection method and the elected metals will be safe to use together.
See the link below from MPS and Logix Group for more information on how galvanic corrosion occurs.
