Abstract: A pneumatic pipe plug for pipeline tee-connections and access ports having a molded cap structure, an elastomeric inflatable body, and a sealant ring. The molded cap structure of the pneumatic pipe plug having two concentrically spaced projections which act to receive and seal the elastomeric inflatable body. The elastomeric inflatable body having a closed bottom and an open top which has a peripheral shoulder extending therefrom. The sealant ring of the pneumatic pipe plug having a threaded exterior and an interior lip which compresses the peripheral ridge of elastomeric inflatable body against the projections of the molded cap structure when the sealant ring is joined to the molded cap structure. The molded cap having an inflation device that is suitable to regulate air flow through the upper surface of the cap and into the area contained within the inner most projection of the lower molded cap.