Sand impingements on cathodic protection of marine carbon steel in natural sea water

In this work, the influence of sand impingements on cathodic protection (CP) of marine carbon steel in natural sea water was studied in comparison with the CP performances in static and flowing sea water without sand particles. Results show that the propagation of local active anodic dissolution at the steel inclusions could be totally inhibited by providing sufficient cathodic current in the sea water free of sand particles. However, the local 'CP shielding', potential fluctuation and sand impingements would enhance the anodic dissolution at inclusions, thus leading to the occurrence of erosion-corrosion under CP. The negative shift of the CP potential could not retard the propagation of erosion-corrosion pits under sand impingements. The synergy of erosion and corrosion might result in long-term failure of local CP.