Coating Health Sensor System and Service Life Model

Computational Mechanics Inc. (CMI) will develop a paint coating condition or"health"monitoring system that can signal without tank entry by an inspector when a coating actually needs possible repair. It will also provide diagnostic assistance in assessing with a high degree of confidence whether or not a coating needs to be replaced through the use of a service life prediction model. The coating sensor can be considered as an enhanced CP system as it will be developed based on the typical components used in a cathodic protection system combined with software simulation technology to provide a"smart"system to identify the current state of the coating system and to forward predict its condition over the life of the vessel. A key innovation will be the integration with the simulation model as this will enable the system to automatically extract and interpret information about the condition of the coating. The simulation model will be based upon similar technology to that used in the BEASY Corrosion and CP software which has been widely used to model Galvanic Corrosion and Cathodic Protection systems. The models are based on Boundary and Finite Element Technology to model the IR drop and electric fields in the electrolyte, models of the electrode kinetics on the metal surfaces and coating degradation models. A key feature of the proposed technology is that results suggest that good predictions of the overall coating condition can be achieved even if the open circuit corrosion potential is unknown, the polarization curve is non-linear and unknown and there are unknown reference electrodes offsets. Therefore the usual detailed inputs into a model are not required. The coating degradation model will provide data on the performance of the coating at a particular location at the time the measurements are made. It will also use historical data to predict how the degradation is expected to change over the service life to provide data for maintenance planning.