Pit

1) A small, sharp depression or cavity produced in a metal surface during electro-deposition or by corrosion. Pits in electro-deposits may or may not pass through to the basic metal and are usually caused by the shielding action of bubbles of gas during deposition. 2) Pockets or cavities created by vaporization of fluid at the point of drawing or rolling as the metal is forced to change its profile or is reduced to a different size. The vaporized bubbles deform the metal under the pressure created at the point of work. 3) A term for the chamber that is usually below grade and designed to hold the reservoirs or be the reservoir for the process fluids of a production facility.