Electric Field Gradient Sensing for Offshore Cathodic Protection Surveying

The inevitability of corrosion presents demanding and expensive challenges for oceanic engineering, and cost-effective solutions are imperative in the current industry. A widely utilized approach for combating corrosion in offshore applications involves equipping underwater structures with cathodic protection (CP) systems. Electric field gradient measurements provide local information to the health of a CP system. These measurements are collected from a pair of differentially compared reference electrodes attached to a remotely operated vehicle (ROV) or other designated craft. We investigate various electrodes for use in CP surveying, namely thin-film platinum and silver/silver chloride (Ag/AgCl) microelectrodes deposited on flexible polyimide foil, as well as platinum bulk electrodes. Ag/AgCl electrodes were fabricated by electrodeposition of silver and partial electrochemical conversion to silver chloride. The possibility for mass fabrication, simple realization of robust multielectrode arrays and cheap costs justify frequent replacements following inevitable contaminations are just a few of the advantages to these flexible sensor chips. Finite element modeling (FEM) provides a baseline standard of what should theoretically be measured. The developed sensor method was successfully applied to measure electric field gradients created by CP systems in saltwater. Electric field mapping experiments in a laboratory setting showed Ag/AgCl microelectrodes to perform the most reliably and accurately when compared to nonpreconditioned, bare platinum counterparts.