If potential monitoring shows the structure is over-protected, what consequence is likely?

Prepare for the Corrosion Prevention and Control Test with multiple choice questions. Learn with detailed explanations, hints, and more. Boost your confidence and pass the test!

Over-protection means the structure is held at a potential more negative than needed for protection. When you push the potential too far negative, water reduction at the metal surface kicks in more strongly, producing hydrogen gas. That hydrogen can form under the coating, causing blistering and coating disbondment, and it can even diffuse into the metal and cause hydrogen embrittlement in susceptible steels. So the likely consequence is excess hydrogen evolution and possible coating damage. This wouldn’t increase coating thickness, and it wouldn’t mean less current or no effect—the current is typically higher than necessary when over-protected, and the problem is the hydrogen-related damage.