What is an Impressed Current Cathodic Protection System?

What is an Impressed Current Cathodic Protection System?

Impressed current systems are generally used in applications with large current requirements, such as buried pipelines, large ships, retrofitting of offshore structures and concrete-rebar structures. Impressed Current Cathodic Protection systems can be applied in soil, fresh water, brackish water, and seawater environment.

Impressed current cathodic protection (ICCP) systems, often referred to as “active” systems, require an external power source to generate a potential difference between the anodes and structure—enabling a large amount of current to discharge from the anodes through the electrolyte and onto the structure being protected. To minimize auto-corrosion of the anodes and achieve longer life of the CP system, the anodes typically used for impressed current systems (e.g., high silicon cast iron and mixed-metal oxide) are much noble on the galvanic series than the structure. For the current to flow in the correct direction and protect the structure, the negative pole of the rectifier is connected to the structure being protected and the positive pole is connected to the anodes.

In impressed current cathodic protection, buried metal structures receive the protection current from an external source or current rectifier installed on the surface, and using a set disperser current in the electrolyte, which consists of an inert anode. The source of the electrical current from by the rectifier converts AC power into a DC current and injects this into the medium by means of inert anodes, whose selection depends on several factors, such as cost, useful life, conductivity, and resistivity of the corrosive medium.