Definition - What does Flange mean?
A flange is a protruding wheel-shaped end of a piece of equipment that is fastened to another end of an object to facilitate attachment. Adjoined flanges often become the focal point of corrosion if not properly managed and monitored.
Corrosionpedia explains Flange
A flange is usually made of metal and affixed to another flanged object via the use of bolts and nuts. The adhering of the various fixtures in immediate physical contact with each other traps oxygen, moisture and other corrosion-inducing substances, ultimately leading to crevice and pitting corrosion.