Abstract: A plumbing test fitting for waste or vent pipes and stacks extending between adjacent floors of a building having a closure plate adapted to be slidably fitted between a pair of spaced adjacent ends of a pair of pipes, the joint being sealed by a detachable sealing clamp which also sealably bears against the periphery of the closure plate. A sliding valve element having an operating stem which extends outwards between the pipes and through the sealing clamp can be operated to open or close a passage in the closure plate so as to enable the pipe to be closed for testing and thereafter opened to permit testing fluid to escape down the pipes.