SANI PRESS impressed current cathodic protection system
Introduction and aims Cathodic protection is a method that has been used since the early 1800s to prevent the corrosion of maritime structures such as ships. Electrochemical corrosion can be prevented if the potential, or voltage, on a metal is altered past a certain value. Impressed Current Cathod
Technical features
Introduction and aims
Cathodic protection is a method that has been used since the early 1800s to prevent the corrosion of maritime structures such as ships. Electrochemical corrosion can be prevented if the potential, or voltage, on a metal is altered past a certain value. Impressed Current Cathodic Protection (ICCP) systems operate with anode current which is supplied by a power supply rather than by a sacrificial metal. Because the system now actively controls the corrosion, anodes can be made from noble metals to minimize deterioration, fewer anodes are required because of the increased output capabilities, and feedback control can be included to closely monitor the hull protection levels.
This is the reason why the best corrosion protection for an underwater hull is an impressed current cathodic system. SANI.PRESS ICCP system consists of nonsacrificial noble anodes connected to power supplies, reference cells to monitor hull potential state, and a controller to adjust the current output of the anodes. Anodes must be located so that the current distribution can be uniformly maintained at all points along the underwater hull.
Working condition
In a two sub-system installations, the total current is divided approximately 60% stern section and 40% bow section. This distribution performs well on large ships of 200-250 m class. The added current in the stern is mainly for protection of appendages (propeller, rudder etc).
The SANI.PRESS performance monitoring is based on the Zinc Reference Electrode potential developed with respect to the steel hull of the ship. There is one control reference electrode per sub-system which feeds the control signal to the automatic power supply. An auxiliary reference electrode may also be employed as on installed spare or as additional verification of the polarisation.
In the stern section, anodes and reference cells are located within the engine room casing or void areas, a minimum of 1.5 meters below the light water line and above the double bottom or ballast tank and a minimum of 4 meters forward of the propeller plane.
In the bow sections anodes and reference cells are usually located in a water ballast tank. In these cases, internal cofferdam are required. The versatility of SANI.PRESS assures optimal solutions for each working condition.