Which practice does NOT mitigate galvanic corrosion in shipboard assemblies?

Which practice does NOT mitigate galvanic corrosion in shipboard assemblies?

• A. Using dissimilar metals with no isolation
• B. Coatings and isolation
• C. Proper material pairing
• D. Sacrificial anodes

Answer: (A)

Galvanic corrosion happens when two different metals are in electrical contact in an electrolyte, like seawater. The metal with the more negative electrochemical potential (the anode) tends to corrode, while the other metal (the cathode) is protected. In shipboard assemblies, preventing that current flow or reducing the potential difference between metals is key to mitigation. Coatings and isolation prevent the electrolyte from reaching the metal surfaces and break the electrical path, so the galvanic current can’t form. Proper material pairing selects metals with compatible electrochemical potentials or minimizes the galvanic difference. Sacrificial anodes provide a willing target that corrodes instead of the structural metal, protecting the joined components. Using dissimilar metals with no isolation does not mitigate galvanic corrosion; it creates a galvanic couple in which the anodic metal will corrode rapidly.

Galvanic corrosion happens when two different metals are in electrical contact in an electrolyte, like seawater. The metal with the more negative electrochemical potential (the anode) tends to corrode, while the other metal (the cathode) is protected. In shipboard assemblies, preventing that current flow or reducing the potential difference between metals is key to mitigation.

Coatings and isolation prevent the electrolyte from reaching the metal surfaces and break the electrical path, so the galvanic current can’t form. Proper material pairing selects metals with compatible electrochemical potentials or minimizes the galvanic difference. Sacrificial anodes provide a willing target that corrodes instead of the structural metal, protecting the joined components.

Using dissimilar metals with no isolation does not mitigate galvanic corrosion; it creates a galvanic couple in which the anodic metal will corrode rapidly.