A water storage tank with no interior coating has a cathodic protected system installed. What will happen to the anodes?

• A. They will disintegrate quickly
• B. They will become plated with zinc
• C. They will remain intact
• D. They will corrode slowly

Answer: (A)

In a sacrificial cathodic protection system, the anodes are designed to corrode in place, sacrificing themselves to protect the steel surface. When the tank interior has no coating, the entire interior steel surface is exposed and requires protective current across a large area. The sacrificial anodes must supply that current, so they dissolve to maintain the protected potential. That means the anodes will disintegrate quickly. They don’t get plated with zinc, they don’t stay intact, and the corrosion rate isn’t slow because the uncoated interior drives higher anode consumption to protect the exposed surface.