What is "crevice corrosion," and where does it typically occur?

Crevice corrosion is a localized form of corrosion that occurs in confined spaces where there is limited access to the surrounding environment. This type of corrosion is particularly insidious because it can develop in areas that are not easily visible or accessible for regular inspection. Typical locations for crevice corrosion include gaps, joints, or under deposits where moisture can become trapped, such as under washers, seals, or in the spaces between components.

In crevice corrosion, the electrolyte (often saltwater in marine environments) becomes stagnant, leading to localized changes in the chemical environment, such as decreased pH and diminished oxygen levels. These conditions can accelerate the corrosion process in the confined area, separate from the bulk material, which remains unaffected.

Understanding the nature of crevice corrosion is crucial for marine engineers and those involved in vessel maintenance as it highlights the need for proper design, material selection, and maintenance practices to mitigate this specific type of corrosion.