Evaluation Of Technical Feasibility On Applying Calcareous Deposit Coatings To Ship Ballast Tanks

摘要

This study evaluated the technical feasibility ofapplying a combination of calcareous deposit coating and cathodicprotection (anodes) in lieu of completely coating ship ballast tankswith high-performance coatings (epoxy). As an initial step toachieve this goal, batches of calcareous deposits were formed onA36 grade carbon steel plates, induced by cathodic polarization(CP) in natural seawater. The effects of deposition parameterssuch as CP current density, potential, and coating time on thecoating's characteristics were evaluated to establish the optimumcoating condition. Results showed that good overall calcareouscoating can be achieved by lowering the current density as much aspossible in the range 0.1-0.5mA/cm~2 and by increasing coating formation time.Optimum number and arrangement of CP anodes for calcareouscoating of a 3-dimensional structure such as a ballast tank werealso evaluated by using Finite Element Method (FEM) analysis ofpotential distribution under CP. The results were fairly consistentwith the experimental data obtained from coating tests made on theinner surface of a box-type, mock-up strcture.