Snap fit sealing gasket with precisely located internal retainer ring for square pipe grooves
A pipe sealing gasket is shown which is designed to be received within a groove provided within the belled, socket end of a plastic pipe. The sealing gasket has a body formed of resilient material and has a retainer ring embedded therein which circumscribes the gasket body. The groove in the plastic pipe is preformed during the manufacture of the plastic pipe and the gasket is installed thereafter. The gasket nominal diameter exceeds the internal diameter of the belled pipe end. The retainer ring is placed within the body of the sealing gasket at a precisely determined location which most effectively retains the ring in position while withstanding the forces of the assembly of the pipe joint.
1. A method for installing a gasket within a square gasket receiving groove provided within the bell end of a pipe section, the bell end having a mouth opening which is engageable with a spigot end of a mating pipe section to form a pipe joint, the method comprising the steps of:
providing a pipe section having a bell end opening;
orienting the pipe section having the bell end along a longitudinal work axis;
providing a sealing gasket formed at least in part of a flexible material, the gasket having a relatively rigid internal retainer ring which circumscribes the gasket interior at one circumferential location;
temporarily transforming the sealing gasket from a generally cylindrical shape to a generally elliptical shape;
inserting the gasket within the mouth opening of the bell end, the annular gasket being oriented at an oblique angle with respect to the longitudinal work axis such that a trailing edge of the gasket engages the annular groove, and a leading edge of the annular gasket is moved past the annular groove provided in the bell end;
exerting a retracting force on the annular gasket by pulling the leading edge thereof backwards in the direction of the mouth opening of the bell end until the gasket again assumes a generally cylindrical shape and snaps into a locked-in position within the annular groove; and
wherein the location at which the relatively rigid ring circumscribes the gasket interior is selected according to the following formula:
R
ib
=
2
D
R
L
D
+
D
G
-
4
E
G
where when R ib is less than 1 gasket installation is possible, and when R ib is greater than 1 gasket installation is not possible; and
where D R =retainer ring diameter;
L D =distance from the bottom of the annular groove to the edge of the groove on the opposite side where the groove is formed by fillets and the distance is drawn along a line that passes through the approximate centers of the corresponding fillets;
D G =diameter of the annular groove;
E G =distance to the groove wall; and
wherein the optimum ring location is determined by the intersection of the lines which represent D R and E G .
2. The method of claim 1 , wherein the pipe sections are formed of synthetic plastic materials.
3. The method of claim 2 , wherein the pipe sections are formed of a synthetic plastic material selected from the group consisting of polypropylene, polyethylene and polyvinyl chloride.
4. The method of claim 2 , wherein the sealing gasket is inserted within the mouth opening of the bell end of the pipe section at an angle less than 90 degrees with respect to the longitudinal working axis of the bell end.
5. The method of claim 1 , wherein the sealing gasket is inserted within the mouth opening of the bell end of the pipe section at an angle greater than 90 degrees with respect to the longitudinal working axis of the bell end.
6. The method of claim 1 , wherein the relatively rigid ring is made of metal.
7. The method of claim 6 , wherein the relatively rigid ring is made of steel.
8. The method of claim 1 , wherein the relatively rigid ring has a cross-sectional diameter which defines a locus of points on an inner surface thereof which is equal to or greater than the internal diameter of the remainder of the bell end of the pipe which joins the annular groove.