The PETRA facility at the Tritium Laboratory Karlsruhe (TLK) has finished its useful life and the glove box and auxiliary systems are being refurbished. During the lifetime of PETRA the glove box became contaminated with a small amount of tritium but the source has not been positively identified. Removing large redundant components would be hazardous as this would require removing the glove box panels and thus exposing the inner surfaces to moist air which would release tritium. Over several months defined amounts of water have been introduced into the glove box daily which has liberated significant quantities of tritium which has subsequently been absorbed by the in-built tritium retention system. This technique has slowly reduced the tritium liberated at each step. The large components, such as a getter bed, catalyst bed and a permeator, have been detritiated as far as possible in-situ in readiness for disposal once it is safe to remove them from the glove box.