Abstract: A shaping element designed to form a sewer pipe receiving opening during pouring of concrete to mould a manhole. The shaping element also holds a gasket seal in position until the concrete is set. The shaping element is made of two axially separable parts each having a flange to form part of the sewer pipe receiving opening. The inner end of one flange has an L-shaped extension defining a radially inwardly extending step and an axially extending end portion, the inner end of the other part extends short of the step and overlaps the axial extension whereby there is formed a gasket seal receiving peripheral channel of L-shaped cross-section. The two parts are completely closed at their outer ends and are assembled by means of non-circular telescopic tubes at their center to maintain the same in a predetermined relative orientation.

Abstract: 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.