This article describes the development of new joint coating and field repair systems on gas and oil transmission lines. Historically, the major problems associated with field applied coating were directly related to the sensitivity of prevailing environmental conditions, such as substrate cleanliness and preparation, and application technique. In lab and field trials, a new generation of heat shrinkable systems have been proven to perform as well as the mainline coating. The emphasis in these new developments, in addition to the “in service” performance, has been the search for systems that stress ease of application and tolerance to environmental conditions.