Cathodic protection with impressed current
In this type of cathodic corrosion protection, the current comes from an external direct current source (rectifier). Usually, the anode is a material that is not consumed significantly (inert anodes). This means that very long lifetimes of this type of cathodic corrosion protection can be achieved. These systems are often projected for a lifespan of 50 years. Common examples of cathodic protection with impressed current are larger water pipes, natural gas pipes and tanks.
As the current flow in this case becomes controllable, much greater opportunities for regulation are obtained in this type of cathodic protection. This type of cathodic protection also offers the possibility of a significantly greater current output. For galvanic cathodic protection, the driving voltage becomes in the order of 0.5 V, while at the applied current voltages up to 50 V, i.e. 100 times more current can be emitted with the same anode geometry under favorable conditions.
ICCP is a method used in corrosion control to reduce the dissolution of anodic structures by reducing the difference between potential energy & the cathodic and anodic sites on the metal surface, when put into an electrolyte environment.
The types and sizes of these components and their positions on the hull are specified according to design parameters which allow for the size of the vessel and fluctuations in the protection current likely to be encountered during sea-going service.