HOW DOES AN ICCP SYSTEM WORK?
– Using an arrangement of hull mounted anodes and reference cells connected to a control panel(s), the system produces a more powerful external current to suppress the natural electro-chemical activity on the wetted surface of the hull.
– This eliminates the formation of aggressive corrosion cells on the surface of plates and avoids the problems which can exist where dissimilar metals are introduced through welding or brought into proximity by other components such as propellers.
The systems are designed to automate the current output while the voltage output is varied. This allows the protection level to be maintained as the seawater resistivity alters.
– In a sacrificial anode system, increases in the seawater resistivity can cause a decrease in the anode output and a decrease in the amount of protection provided. But with ICCP systems protection does not decrease in the range of standard seawater.
– An essential feature of ICCP systems is that they constantly monitor the electrical potential at the seawater/hull interface and carefully adjust the output to the anodes in relation to this. Therefore, the system is much more effective and reliable than sacrificial anode systems where the level of protection is unknown and uncontrollable.
This animation shows how Cathelco impressed current cathodic protection (ICCP) systems protect the hulls of commercial vessels against corrosion.
Cathelco, UK. (www.cathelco.com).