Abstract: A method of cleaning a nitric acid absorption column cooling coil having an access port and an exit port comprising the steps of closing the access port, inserting a pig in an operative position within a sealable cavity of a launching assembly that is operatively attached to the access port to allow the pig to enter the coil, pressurizing the launching assembly with a fluid to a pre-determined level, opening the access port while maintaining pressure against the pig during its passage through the coil by a fluid pump sufficient to force the pig into and through the coil, and capturing the pig after it passes through the exit port.