In galvanic corrosion minimization between metals in seawater, which approach best minimizes galvanic corrosion?

• A. Increase the anodic metal's current by thinning protection.
• B. Remove all protective coatings from one metal.
• C. Use identical metals.
• D. Electrically isolating the metals with barriers or coatings to prevent galvanic current flow.

Answer: (D)

Galvanic corrosion happens when two metals with different electrochemical potentials are in electrical contact in an electrolyte, such as seawater. The electrolyte completes the circuit, allowing electrons to flow from the more active metal (the anode) to the less active metal (the cathode). This drives accelerated dissolution of the anodic metal. The surest way to prevent this is to break the electrical path between the metals. By electrically isolating them with barriers or coatings, you stop galvanic current flow entirely, so neither metal experiences the accelerated corrosion caused by their coupling.

The other approaches don’t prevent the galvanic current. Increasing the anodic metal’s current by thinning protection just speeds up its corrosion. Removing protective coatings from one metal exposes it and promotes corrosion. Using identical metals reduces the potential difference, but it doesn’t guarantee no galvanic current if coatings fail or if there are other contact points; isolation remains the most reliable method to minimize galvanic corrosion in seawater.