ABSTRACT
The designer of an external Cathodic Protection (CP) system never needs to consider what happens to the dissolution products of the anode. However, once the movement of the seawater is constrained, as is the case in internal CP, the effect of the anodic dissolution products on the local chemistry of the seawater needs to be considered. Inevitably, the ingress of oxygenated seawater into a monopile invalidates the original “in-air” fatigue design assumption. It is this consideration that prompted many wind farm owners to retrofit internal CP in existing mono-piles and to design new monopiles with CP installed from the beginning. Internal CP of a carbon steel seawater pipeline only has a chance of being successful if it has a large diameter and is internally coated. The internal CP of the unlined carbon steel seawater piping is unlikely to be practicable.
