Cathodic Protection (CP) for Corrosion Control
Cathodic protection (CP) is a critical component of corrosion mitigation. An electrochemical process, CP is a branch of chemistry dealing with the chemical changes that accompany the passage of an electric current, or a process in which a chemical reaction produces an electric current.
It is used to control the corrosion of a metal surface by transferring the corrosion from the protected structure to a more easily corroded metal. In other words, it controls the corrosion of a metal surface by making it the cathode of an electrochemical cell. It’s accomplished by sending a current into the structure from an external electrode and polarizing the metallic surface in an electronegative direction. This provides protection to the surface and extends the life of the asset.
Examples of structures where cathodic protection systems are employed include underground tanks and pipelines; aboveground storage tanks; water tank interiors; ship hulls; ballast tanks; docks; sheet piling; land and water foundation piles; bridge substructures; tube sheets; oil heater treaters; and reinforcing steel in concrete.
Important considerations for CP management are
- material selection and design to minimize corrosion, and
- items that should be addressed in cathodic protection control planning, which affect CPC in design, fabrication and construction, operation and use, and maintenance and sustainability.