Sealing gasket with corrugated insert for sealing restrained or non-restrained plastic pipelines
A pipe sealing gasket is shown which is designed to be received within a raceway provided within a socket end of a female bell plastic pipe end which is assembled with a mating male spigot pipe end to form a plastic pipe joint. The raceway in the female bell plastic pipe end is preformed during manufacture and the gasket is installed thereafter. The gasket has a rubber body portion which is reinforced by a hard corrugated ring-shaped insert. The hard corrugated ring-shaped insert acts to prevent extrusion of the gasket during a variety of pressure conditions as well as preventing displacement during field assembly.
1. A pipe sealing gasket designed for receipt within a raceway provided within a female belled socket end of a thermoplastic pipe, whereby fitting the gasket within the raceway allows a mating male pipe having a spigot pipe end to be inserted therein to form a continuous pipe joint, the gasket comprising:
a ring shaped elastomeric body having a main body portion formed of rubber which, when viewed in cross section, includes a leading nose region, a lower compression region and a trailing tail region, the leading nose region capable of facing generally towards the female socket end of the pipe once the gasket is inserted within the raceway of the female bell socket end of the pipe;
wherein the leading nose region of the main body portion of the gasket is reinforced by a hard plastic band, the hard plastic band comprising a corrugated ring member formed as a series of interconnected alternating crest and root regions, the hard plastic band being embedded within the leading nose region of the main body portion of the gasket during gasket manufacture;
wherein the alternating crest and root regions define a generally conical area on an exterior region of the hard plastic band and a generally cylindrical area on an interior region of the hard plastic band, the alternating crest and root regions also defining an entire circumference of the hard plastic band, and wherein the hard plastic band has a uniform wall thickness about the entire circumference thereof;
wherein hydraulic pressure due to fluid in the pipe acts upon alternating the crest and root regions of the hard plastic band to push the alternating crest and root regions into tighter engagement with the mating male and female pipe members to prevent extrusion of the gasket from the raceway provided in the female belled socket end of the thermoplastic pipe once a spigot end of a mating male pipe is installed to form a pipe joint and the pipe is conveying fluid; and
wherein the corrugated ring member with its alternating crest and root regions is stretchable from an initial relaxed diameter to an expanded diameter which allows it to be stretched when placed into an injection mold cavity and yet return elastically to an intended diameter as surrounding rubber in the mold cavity shrinks during an injection molding operation.
2. The pipe sealing gasket of claim 1 , wherein the sealing gasket has an outer conical surface for mating with walls of the raceway provided in the female belled pipe end, and wherein the crest regions of the corrugated ring member are exposed from the conical surface of the sealing gasket after manufacture at regular spaced intervals, and wherein the exposed corrugated ring member is for contact with the raceway walls and for preventing extrusion of the sealing gasket from the raceway.
3. The pipe sealing gasket of claim 2 , wherein the exposed crest regions of the corrugated ring member are capable of acting as a restraint mechanism for a pipe joint.