Cathodic Protection


While metals are always vulnerable to corrosion and degradation when left unprotected and exposed to the elements, they face particular risk when left exposed for long periods of time underwater. Companies making use of steel and other metals for applications that involve long-term submersion have developed techniques to fight off metal corrosion using a process known as Cathodic Protection (CP). This treatment of metals is most commonly seen in manufacturing processes that involve producing metals for applications that include piping, shipbuilding, production of concrete-embedded steel, and various marine applications.


Applying Cathodic Protection to any metal involves an electrochemical process. The metal surface of the product is altered by making the actual exposed surface the cathode of an electrochemical cell. The corrosion protection comes into play thanks to the creation of an added layer of protection that this process induces. The protective layer that is created is actually more susceptible to corrosion, allowing it to act as an anode or “sacrificial metal” that guards the primary metal surface of the product. While it may sound as if this complicated process would be reserved for advanced metals that are only involved in expansive construction projects, this technique is present in homes and small projects all over the world.


Galvanized steel is generally protected using this process. The steel is given a coating of sacrificial zinc that corrodes more easily in order to protect the structural integrity of the steel itself. The CP process is also commonly used to protect metals that are used to produce water heaters in homes and storage tanks on small properties that are used to contain petroleum or natural gases. Projects that require industrial-level production for this treatment in order to ensure the long-term safety of their applications include off-shore oil rigs and reinforced concrete in large-scale buildings and housing developments. Steel and other metals that are put under strain for extended periods of time while exposed to harsh elements have been known to suffer from stress corrosion cracking when this type of protection is not put into place.


The actual anodes and sacrificial metals that are used in the practice can vary based on the project, the conditions where the metal will be used, and the underlying metal that requires protection. Among the most common anodes are zinc, aluminum, platinum, and carbon. The anodes are also designed to increase the efficiency and performance of the metal based on the given application as well. For instance, galvanic anodes are the most common solution for fighting corrosion on ships thanks to its flexibility in regard to shape and production standards. It can be outfitted to provide corrosion protection while also minimizing the drag produced by its interaction with moving water.


Applying CP protection to metal surfaces is typically done after the metal itself has been shaped and fabricated. However, the process varies slightly when it comes to protecting steel that is embedded in concrete. In these instances, the protective technology is applied at the time of manufacturing, being embedded in the concrete along with the metal itself. It is also possible for cathodic protection to be applied to the interior of metal products as well. These strategies are most often used when constructing pipelines that transport hazardous materials or when constructing storage containers for water, including conventional water heaters.


The process was first refined using iron and copper sheathing on the bottom of boats and large vessels. However, the rudimentary technology first resulted in the increased growth of marine life, posing a completely different problem for engineers. The incorporation of an electric current and the allotment of outer corrosion soon proved to be effective on all fronts, quickly leading to the cathodic protection methods that we use today. Go to for more information on this indispensable technology used in modern metals.