Flange nuts are a type of nut that have a wide, washer-like flange on one end. The flange provides a larger surface area that can distribute the load more evenly and prevent damage to the surface of the object being fastened.

The flange on a flange nut may have serrations or teeth on the underside to provide additional grip and prevent the nut from loosening over time. Flange nuts may also be designed to compress the threads on a bolt, which helps to create a secure, non-slip connection that resists vibration.