Corrosion Protection

Impressed Current Cathodic Protection (ICCP) is a proven system for protecting stainless steel against electrochemical corrosion.

The basic principle is that the metallic object to be protected is made a cathode which does not corrode. This is achieved by continuously supplying electrons to the metal via an external current system. The system consists of several reference electrodes and several anodes. The anodes are connected to a power supply unit and emit the protective current into the conductive water. Almost all surfaces of the protected object immersed in the water are reached by the protective current.

The reference electrodes measure the electrical protection potential and, based on this data, the power supply unit automatically regulates the required power at the anodes. The protective current given via the anodes leads to a change in potential on the surface of the protected object and prevents the corrosion process.

Advantages of cathodic corrosion protection with sacrificial current are that relatively large surfaces and structures are effectively protected, comparatively few anodes are required and the applied voltage adapts to changing environmental conditions.

Corrosion protection can also be achieved by using galvanic anodes, the so-called sacrificial anodes. These consist of an electrochemically less noble metal, usually aluminium, zinc or magnesium, which is connected to the protected object through the seawater acting as an electrical conductor. The decisive factor for effective corrosion protection is that the sacrificial anodes are either mounted directly on the protected object or are directly connected to it via a metal cable.

The less noble material of the sacrificial anode oxidises and gives off its electrons, which flow as a protective current to the protected object. The object acts as a cathode, so to speak. The sacrificial anode dissolves during the process and protects the protected object from corrosion.

Sacrificial anodes must be replaced at the end of their service life, which is usually after a period of 2 to 5 years. They have the advantage of relatively low material costs, they are relatively easy to install and do not require a power source. In addition, they are suitable for localised protection and are less susceptible to interaction with neighbouring structures. A disadvantage is the lack of control and direct measurability compared to cathodic protection with external current.