Gasket seal between sewer pipe and manhole opening

摘要

An annular gasket is provided to provide a leak proof seal between the surface of an opening through the wall of a manhole and the outer surface of a pipe which passes through said opening. The gasket is made of elastomeric material and has a cross-section defining a radially outward T-shape portion embedded in the concrete of the manhole wall around the opening. The gasket further includes a radially inner enlargement tapering radially inwardly and terminated by a laterally directed lip. The enlargement and lip are flexed by the pipe inserted through the opening with the maximum thickness of the enlargement forming a sealing ridge contacting the pipe in a first zone and with the lip also contacting the pipe in a second zone with a void between the first and second zones. The surface of the manhole opening has a channel for receiving the anchoring part of the gasket and on each side of the channel two frusto-conical surface portions of different minimum diameter; the frusto-conical surface portion of lesser minimum diameter being disposed on the side of the lip and acting as a solid stop for the pipe when subjected to abnormally high shearing force so that the portion of the gasket diametrically opposite said stop will not disengage the pipe.