Which statement is true about crevice corrosion control?

• A. It can be achieved by simply adjusting color of coating
• B. It cannot be controlled
• C. It is best controlled by cleaning only
• D. It is controlled by design and cathodic protection

Answer: (D)

The main idea here is that crevice corrosion is best controlled by removing or reducing the crevice environment and by applying protective electrochemical measures. Crevice corrosion forms where tight gaps trap solution and restrict oxygen access, creating a localized, aggressive chemistry that drives rapid attack. By designing joints and connections to minimize crevices, using sealants or gaskets that do not trap solution, and choosing compatible materials, you reduce the places where this localized attack can start. Adding cathodic protection shifts the metal’s potential to a more negative value, lowering the driving force for dissolution inside any remaining crevices and helping to suppress corrosion where crevices exist. Coatings can support protection, but they don’t replace the need for proper design and CP.

Color changes in coatings are cosmetic and do not address the electrochemical conditions that cause crevice corrosion. Cleaning alone removes deposits but does not eliminate the crevice itself or alter the local chemistry driving the attack, so it isn’t sufficient as the sole control method. And since effective design and cathodic protection can prevent or greatly reduce crevice corrosion, saying it cannot be controlled isn’t accurate.