Use a pipe plug or test plug to help seal off the ends of metal or PVC pipe. Test plugs are designed to test pressure in dry waste and venting (DWV) stack vents and other vent pipe. Pneumatic pipe plugs can be used in an inflatable rubber bladder to seal pipe ends. Shop Grainger today for the pipe and test plugs you need to help repair and test water, sewer and general plumbing systems.