Computer Modeling of Impressed Current Cathodic Protection (ICCP) System Anodes

Computer modeling is now widely used to predict how effective cathodic protection (CP) systems are at protecting structures and maritime vessels. There are two types of CP systems based on either sacrificial anodes or impressed anodes (ICCP) or some combination of the two types. Impressed anodes are often referred to as “active” systems as they can respond to changes in the protection requirements as they are connected to some form of control system. Typically in computer models ICCP anodes are controlled by specifying the current they output in response to the potential measured at a reference electrode. In this paper an alternative approach has been investigated where the model also includes the power supply as well as the associated cables etc connecting to the anodes. This enables us to more accurately model situations where any number of anodes are connected to a single power supply, anode/reference electrode (RE) failure scenarios, non symmetric anode layouts, localized damage to coatings and situations where there are significant appendages to the vessel which change the current requirements. The paper will describe the technical approach to the modeling and present examples of modeling of a commercial FPSO vessel. (Floating, Production, Storage and Offloading vessels are used in the Oil & Gas industry typically as part of deepwater developments) The benefits of the proposed approach compared with the conventional approach will be presented and the results critically analyzed.