The goal of Corrosion control is to eliminate the natural corrosion process. A properly designed, equipped and installed cathodic protection system is the only sure and safe way to protect immersed, water-containing and buried metal structures from corrosion
Corrosion protection prevents corrosion by reversing the corrosion process. By introducing positively charged anodes to the system cathodic protection equalizes the electrical potential to all parts in the structure. The flow of corrosive electrical currents is stopped and corrosion is control.
Whereas paints and coating slow down corrosion attack by setting up barriers, cathodic protection is positive and active: it suppresses attack at the outset. Paints and coatings wear and deteriorate and are subject to mechanical damage. Even a pin hole allows immediate onset of corrosion at the surface of the metal; coating are undermined by the products of corrosion and large areas are left completely open to attack. Cathodic protection provides overall protection and is independent of the conditions of the metal surface.
Cathodic protection is an Electro-chemical technique in which the structure is protected against corrosion by applying an external current in a direction opposite to that of the corrosion current.
The technique is used to protect existing as well as new structure. Cathodic protection current flows from the anode through the electrolyte to the protected surface (cathode). The circuit is completed by connection of the cathode to the power source. As the current passes from the anode to the electrolyte the anode material is slowly consumed. It flows then that corrosion is not eliminated by the application of cathodic protection but is simply transferred from the structure to the anode .