It is generally accepted that destructive interference can occur between impressed and sacrificial cathodic protection systems, which can result in difficulty with control of the ICCP system, and which can also cause problems with performance of the sacrificial CP system.
Less well known is the possibility of interference between multiple sacrificial CP systems. Such interference can occur under a number of different circumstances, and may for example arise when different design approaches are used for sub-structures which are then to be integrated together. Each CP system may be competently designed for stand-alone operation, but when combined together, protection potentials and life of the systems may be affected by interference. Consequences may include early consumption of anodes and more positive potentials towards end of life.
Such effects can readily occur when different types of anode material are used, but may also occur when anodes in both CP systems are made from the same anode material. This paper shows how mathematical modelling has been used to simulate performance of both stand-alone and integrated sacrificial systems. It goes on to identify interference effects between such systems, and investigates a number of different situations in which destructive interference can occur. Conclusions are reached of practices that can be adopted to avoid such destructive interference.
Key words: Galvanic anodes, sacrificial anodes, Cathodic Protection, Interference
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