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Galvanic corrosion occurs when one metal causes corrosion in another metal because of differing potential voltages. Learn more about how a Sacrificial Anode Cathodic Protection system takes advantage of this natural phenomenon to prevent corrosion in valuable metal structures.
Metal structures exposed to the environment will corrode over time.
Sacrificial Anode Cathodic Protection is a method of mitigating corrosion to these important structures.
(Underground view of a Cathodic Protection System for a Pipeline. This scene focuses on introducing the components of a Cathodic Protection System.)
Cathode: In a Cathodic Protection System, the Cathode is the metal structure that we want to mitigate corrosion on.
Soil: The Cathode and Anode must be immersed in a medium that allows ions to flow freely – Earth or Water.
Anode: The Anode a metal that is more reactive than the Cathode, and will donate electrons to the Cathode, causing the Anode to corrode.
There must be an electrical connection between the Cathode and Anode, so that there is a return path for current flow.
(Same underground view of Cathodic Protection System for a Pipeline. This scene focuses on how the components of the Cathodic Protection System work together to mitigate corrosion.)
The moisture in the soil serves as the electrolyte which causes ions to move freely.
Since this is a more active metal, it’s more likely to lose electrons, as a result, corrosion begins.
Negative electrons are forced to travel from the anode to the structure. As the electrons flow to the cathode, it creates chemical reactions which in turn help mitigate corrosion.
As the electrons flow to the cathode, it creates chemical reactions which in turn help mitigate corrosion.
In Sacrificial Anode Cathodic Protection, no external current source is used. The electric potential difference between the Anode and Cathode are what causes current to flow.
The most common metals used in Sacrificial Cathodic Protection are Aluminum, Zinc and Magnesium.
The advantages of a Sacrificial Anode Cathodic Protections system are:
No external electrical current is required
It is easy to install
Is it less expensive to install than other types of Cathodic Protection systems
The disadvantages of a Sacrificial Anode Cathodic Protection system are:
Anode current is uncontrollable, making it more difficult ensure protection throughout the entire metal structure
It requires frequent monitoring and replacement of anodes.
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About Allied Corrosion
Allied Corrosion Industries, Inc. is a full service corrosion control corporation providing design, installation and maintenance of corrosion solutions and cathodic protection systems since 1980. We are also a materials and test equipment provider, offering a full line of corrosion-related products.