Cathodic Protection Measurement and Modeling

Marine structures and ships fight a constant battle against corrosion. Sacrificial anodes and impressed-current cathodic protection (ICCP) are two common protection techniques. Many structures employ a hybrid configuration of both, in the hope that the combination provides more protection than either does individually. Doing so, however, can create situations in which these techniques interfere with each other. It is essential to verify that protection extends adequately to all areas of the structure. This article describes instrumentation and measurement strategies to determine the corrosion potential and extent of ICCP protection in difficult-to-reach areas on ships. A case study is presented for these methods on a vessel that experienced severe galvanic corrosion damage in its stern tube. Operators of mission-critical marine structures can use these insights to tune and improve corrosion protection schemes before damage manifests.