Crevice Corrosion
What is Crevice Corrosion
Crevice corrosion is a localised form of corrosion that occurs within confined spaces, such as crevices, cracks or gaps. Because there’s little airflow or movement inside these gaps, the protective layer on stainless steel may start to break down. This makes the alloy more susceptible to corrosion than normal. Over time, the trapped liquid becomes more acidic, causing the material in the crevice to wear away much more quickly than on open surfaces.
How Crevice Corrosion Occurs in Stainless Steel
Stainless steels rely on a thin passive oxide layer to prevent corrosion. But in crevices, the lack of fresh air and flowing liquid changes the chemical balance. Ions and chlorides accumulate, pH drops, and an electrical potential difference forms between the crevice interior (anodic) and exterior surface (cathodic). These combined effects drive dissolution within the gap. Factors such as chloride concentration, temperature, crevice width and fluid stagnation further influence susceptibility.
Common Places Where Crevice Corrosion Occurs
Crevice corrosion typically arises in areas where two surfaces meet and trap stagnant fluid. Common zones include gaps under gaskets, seals or washers, overlapping joints or seams in welded assemblies, fastener interfaces, overlapping surfaces and inside cracks or voids. Stainless steel components in oil & gas, marine, and water systems are particularly at risk due to exposure to chloride-rich fluids, elevated temperatures and challenging service conditions.