Abstract: An expansion joint includes first and second conduits connected by an expansion joint element. The second conduit has a liner portion which protrudes into the first conduit, so that the expansion joint element, first conduit, second conduit and liner portion together define an expansion joint cavity. A cartridge is located within the expansion joint cavity and is affixed to an end portion of the first conduit. The cartridge has a groove which faces the liner portion and houses a ring which slides within the groove while maintaining sliding contact with the liner portion of the second conduit. The outer diameter of the groove is preferably larger than an outer diameter of the ring to allow lateral movement of the first and second conduits relative to one another. Either the expansion joint cavity or the cartridge groove may be provided with a purge fluid inlet to prevent the intrusion of the service fluid and its associated contaminants into the expansion joint cavity.