_____________ and __________ are used to control crevice corrosion.

• A. Design and passivation
• B. Design and cathodic protection
• C. Cleaning and inspection
• D. Coatings and sealants

Answer: (B)

Crevice corrosion is driven by localized chemistry in a confined space where the solution becomes stagnant and oxygen levels differ, creating a strong corrosion driver in the crevice. You tackle this by two complementary approaches: changing the design to minimize or eliminate crevices, and applying cathodic protection to suppress the metal’s tendency to corrode in those areas.

Design changes reduce or remove the environmental niches where crevice corrosion can develop, such as avoiding tight joints, using compatible metals, and preventing trapped gaps or gasketed interfaces that disrupt fluid flow. When crevices cannot be avoided, cathodic protection helps by shifting the metal potential to more negative values, making dissolution less favorable and limiting localized attack inside the crevice.

Other options are less effective as primary controls: passivation helps with general corrosion but may not prevent attack in crevices, especially if a crevice traps corrosive solution; cleaning and inspection manage problems after they occur rather than preventing crevice formation; coatings and sealants can reduce exposure, but they may degrade over time and still rely on the crevice being sealed, whereas design and CP provide more robust, targeted control.