text: Epoxy and modified epoxy are standard coatings used to provide protective barriers to corrosion in ballast tanks. Exposed, unprotected steel will corrode much more rapidly than steel covered with this protective layer.  Many ships also use sacrificial anodes or an impressed current for additional protection.  Empty ballast tanks will corrode faster than areas fully immersed due to the thin - and electo conducting - moisture film covering them.
  The main factors influencing the rate of corrosion are diffusion, temperature, Conductivity, type of ions, pH, and 
  electrochemical corrosion potential.