Which of the following is NOT considered a type of flow and velocity corrosion?

The correct choice identifies crevice corrosion as the option not considered a type of flow and velocity corrosion.

Impingement corrosion, cavitation corrosion, and erosion corrosion are all forms of corrosion that occur due to the movement of fluid and its interaction with solid surfaces. Impingement corrosion is primarily caused by high-velocity fluid impinging on a surface, leading to localized corrosion where the flow is disrupted. Cavitation corrosion occurs when vapor bubbles form and collapse in a liquid, creating shock waves that can erode surfaces. Erosion corrosion results from the mechanical wear and metal loss caused by the flow of a fluid containing solid particles.

In contrast, crevice corrosion happens in confined spaces where stagnant water resides, such as under a gasket or inside a joint. It is not directly tied to the flow or velocity of a fluid but instead is dependent on concentration cells forming in areas that are less accessible to corrosion inhibitors, leading to localized attack. Understanding the different mechanisms of corrosion is critical in marine applications, as they can affect material selection and design considerations to minimize these types of corrosion.