CATHELCO is World leader in Seawater Pipework Anti Fouling(AF) and Impressed Current Cathodic Protection(ICCP) systems.
Anti Fouling (AF) systems.
The settlement and growth of marine life forms in salt water piping systems in ships and other marine installations can be very costly. The resulting problems include overheating and possible shut-down of machinery, accelerated corrosion, and reduced firefighting capability.
The flow velocity and temperature in these systems are more often than not ideal for encouraging the larvae of marine animals to enter the adult stage after they have passed through the inlet strainers, and settle on the available surfaces of pipes, heat exchangers, valves, etc. The most common culprits are blue mussels, barnacles and tubularia.
It is not practical to filter out the tiny spores and larvae of these creatures, thus filtration has to be supplemented with water treatment.
Cathelco anti-fouling systems are based on the fact that the main fouling organisms can be inhibited from growing by the introduction of very small quantities of copper into the water. The required dosage per litre is only a few parts per billion. This amount is of the same order of magnitude as the copper content in a typical sample of sea water. Copper is introduced into the water flow by electrolysis, in the form of positive ions. Thus the principle is known as copper ion generation, or CIG. Sea water is a good electrolyte, and a low DC voltage is sufficient to provide the necessary current.
Impressed Current Cathodic Protection (ICCP) systems.
Preventing Hull Corrosion with ICCP Systems.
Although modern hull coatings can provide some protection against corrosion they seldom offer a complete solution. For this reason, most operators choose to protect their vessels with a purpose designed impressed current cathodic protection system.
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.
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.