Originally pigs were used in the oil and gas business. They were used to retrieve high value products in the process line as well as to clean the line of build up. The projectile (pig/pusher) generated a squealing noise as it sped through the pipeline, therefore the name pig. Pigging, as a manufacturing process, is where a pig is sent down a piping system to clean the pipe and/or recover product in the line. This process is used in many food and beverage, cosmetics, and pharmaceutical application for the same reasons.