What is a recommended method to minimize galvanic corrosion risk for a carbon steel frame near an aluminum curtain wall in marine spray?

• A. Expose all metal surfaces to air to oxidize.
• B. Use only the carbon steel and remove aluminum.
• C. Use insulating barriers or coatings between metals.
• D. Increase reliance on paint on aluminum only.

Answer: (C)

Galvanic corrosion happens when dissimilar metals are in electrical contact in a salty, wet environment, such as marine spray. The electrolyte enables a galvanic cell, causing the anodic metal (one of the two metals) to corrode at the interface where they touch. The best way to minimize this risk is to keep the metals from forming a conductive path between them by using insulating barriers or coatings between the carbon steel frame and the aluminum curtain wall. Non-conductive spacers, gaskets, or isolation materials, along with protective coatings that create a continuous insulation over the touching surfaces, prevent electrical contact and block the galvanic current. Make sure joints and fastener interfaces are also protected and maintained; relying on paint on one metal alone won’t fully prevent galvanic action if any metal-to-metal contact remains.