US-12618501-B2 - Spline lock restrained pipe joining system for plastic pipe

US12618501B2US 12618501 B2US12618501 B2US 12618501B2US-12618501-B2

Abstract

A restrained pipe joining system for plastic pipe is shown comprising male and female ends each having aligned circumferential grooves which form a canal for passage of a locking keystrap. The keystrap can be formed of PEEK or PEEK reinforced with glass fiber. During manufacture, the female belled end is sequentially formed over a Rieber style gasket and then over a ring-shaped casing member. The casing member is also formed from polymeric composite materials. In some cases, the casing is reinforced with an internal metal band.

Inventors

Mark A. Weih
Guido Quesada

Assignees

S&B TECHNICAL PRODUCTS, INC.

Dates

Publication Date: 20260505
Application Date: 20240422

Claims (9)

1 . A joining system for use in assembling a restrained joint of a first and second sections of plastic pipe, the joining system comprising: a first section of plastic pipe having a female, belled pipe end with an end opening and having an exterior surface, an interior surface and having a circumferential recess formed in the belled pipe end adjacent the end opening on the interior surface thereof; at least one bore communicating the exterior surface of the belled pipe end with the interior recess thereof; a second section of plastic pipe having a mating male plastic pipe end having an interior surface and exterior surface, and wherein the exterior surface has at least one groove formed at one circumferential location thereof which is alignable with the interior recess formed in the belled pipe end when the male pipe end is inserted within the mouth opening of the belled pipe end to form a joint; a ring-shaped casing member installed within the circumferential recess provided in the belled end of the first section of plastic pipe, the ring-shaped casing member having an inner circumferential surface and an outer circumferential surface and having at least one groove formed at one inner circumferential location on the inner circumferential surface thereof, wherein at least one bore extends from the outer circumferential surface to the groove which is provided on the inner circumferential surface thereof, and wherein the bore of the ring-shaped casing member aligns with the bore in the belled end of the first section of plastic pipe whereby the bores, in combination with the aligned recess and groove, form a canal passageway; a flexible keystrap adapted to be inserted at least partly through the canal passageway, wherein the flexible keystrap is made of polyether ether ketone (PEEK) or PEEK reinforced with glass fiber; an associated sealing element co-located within the circumferential recess provided in the first section of plastic pipe adjacent the ring-shaped casing member, the sealing element having an inner circumferential region and an outer circumferential region, the outer circumferential region being arranged to form a seal with the interior surface of the belled end while the inner circumferential region forms a sealing surface for the exterior surface of the mating male pipe section; and wherein the ring-shaped casing member is made of PEEK, polyethylene terephthalate (PET), or polypropylene (PP) and glass or carbon fiber reinforced versions thereof.
2 . The joining system of claim 1 , wherein the ring-shaped casing member and associated sealing element are both located within the female belled pipe end during manufacture of the pipe in a Rieber style manufacturing operation.
3 . The joining system of claim 2 , wherein the sealing element is located within the circumferential recess of the belled pipe end rearwardly of the ring-shaped casing member, the sealing element having a downwardly extending sealing lip which is contacted by the exterior surface of the mating male plastic pipe during the assembly of a pipe joint.
4 . The joining system of claim 1 , wherein the ring-shaped casing member is is filled with 15 to 30% by weight glass or carbon fiber.
5 . The joining system of claim 1 , wherein the keystrap has a curvature equivalent to 1.4 to 1.6 times the radius of the canal passageway.
6 . A joining system for use in assembling a restrained joint of a first and second sections of plastic pipe, the joining system comprising: a first section of plastic pipe having a female, belled pipe end with an end opening, an exterior surface, an interior surface, and having a heat and expansion formed interior circumferential recess formed in the belled pipe end adjacent the end opening on the interior surface thereof; at least one bore communicating the exterior surface of the belled pipe end with the interior circumferential recess thereof; a second section of plastic pipe having a mating male plastic pipe end having an interior surface and exterior surface, and wherein the exterior surface has at least one groove formed at one circumferential location thereof which is alignable with the interior circumferential recess formed in the belled pipe end when the male pipe end is inserted within the mouth opening of the belled pipe end to form a joint; a ring-shaped casing member installed within the heat and expansion formed interior circumferential recess provided in the belled end of the first section of plastic pipe, the ring-shaped casing member having an inner circumferential surface and an outer circumferential surface and having at least one groove formed at one inner circumferential location of the inner circumferential surface thereof, wherein at least one bore extends from the outer circumferential surface to the groove which is provided on the inner circumferential surface thereof, and wherein the ring-shaped casing member is positionable so that the bore of the ring-shaped casing member aligns with the bore in the belled end of the first section of plastic pipe, whereby the bores, the at least one groove of the ring-shaped casing member, and the at least one groove of the second section of the plastic pipe form a canal passageway; a flexible keystrap adapted to be inserted at least partly through the canal passageway when the first and second plastic pipes are joined, wherein the flexible keystrap is made of polyether ether ketone (PEEK) or PEEK reinforced with glass fiber a ring-shaped elastomeric sealing element installed within the same heat and expansion formed interior, circumferential recess provided in the first section of plastic pipe as the ring-shaped casing member and in contact with the ring-shaped casing member, the sealing element having an inner circumferential region and an outer circumferential region, the sealing the outer circumferential region forming a seal with the interior surface of the belled end of the first pipe and the inner circumferential region forming a seal with the exterior surface of the mating male pipe section when the male pipe end is inserted within the opening of the belled pipe end, the sealing element being installed within the circumferential recess of the belled pipe end rearwardly of the ring-shaped casing member and of the end opening of the bell pipe end; wherein the ring-shaped casing member has a leading edge and a trailing edge, the trailing edge being provided with a recessed profile which mates with and engages a leading nose portion of the sealing element so that while the sealing element and the ring-shaped casing member are separate elements, the sealing element and the ring-shaped casing member are interengaged with the leading nose portion of the sealing element extending into the recessed profile of the ring-shaped casing member, the interengagement to secure the sealing element within the interior of the circumferential recess; and wherein the ring-shaped casing member is made of PEEK, polyethylene terephthalate (PET), or polypropylene (PP) and glass or carbon fiber reinforced versions thereof.
7 . The joining system of claim 6 , the sealing element having a downwardly extending sealing lip which is contacted by the exterior surface of the mating male plastic pipe to form a lip seal during the assembly of the coupling.
8 . The joining system of claim 6 , wherein the ring-shaped casing member is filled with 15 to 30% by weight glass or carbon fiber.
9 . The joining system of claim 6 , wherein the keystrap has a curvature equivalent to 1.4 to 1.6 times the radius of the canal passageway.

Description

1. CROSS-REFERENCE TO RELATED APPLICATIONS The present application claims priority from an earlier filed provisional application, Ser. No. 63/499,574, filed May 2, 2023, entitled “Spline Lock Restrained Pipe Joining System for Plastic Pipe”, by the same inventors. BACKGROUND OF THE INVENTION 2. Field of the Invention The present invention relates generally to a restrained joint for coupling plastic pipe and, more specifically to such a restrained joint which utilizes a spline or keystrap to connect a male spigot pipe end to a mating female belled pipe end. 3. Description of the Prior Art A variety of piping systems are known for the conveyance of fluids which employ elastomeric type sealing rings or gaskets. The pipes used in such systems may be formed of PVC, polyolefins such as PE and PP, ductile iron, concrete, clay, fiberglass, steel, cast iron, fiberglass/cement reinforced pipes and such metals as aluminum and copper. At the present time, pipes formed of thermoplastic materials, including PVC and polyethylene, are preferred for use in pipeline installations for below ground pressure piping such as might be encountered in municipal water systems as well as for low pressure or non-pressure pipelines such as those carrying sewage. In forming a joint between thermoplastic sections of pipe of this general type, the spigot or male pipe end is inserted within the female or socket pipe end. An annular, elastomeric ring or gasket is typically seated within a groove formed in the socket end of the thermoplastic pipe. As the spigot is inserted within the socket, the gasket provides the seal capacity for the joint. In many situations, it is also desirable to provide a “restrained joint” to insure the spigot or male pipe end and the female or socket end do not separate due to hydraulic forces that exist inside the pipeline, or due to other causes, such as ground movement and the like. The need to restrain lengths of pipe coupled together in this general fashion exists not only with respect to municipal water lines, but in other diverse applications including well casings, directional drilling applications, laying of fiber optic cable, and above ground pressure piping applications. Over time, various solutions have been proposed for providing the needed restraining function for such applications. In each of the above described example conduit and pipeline applications, it is desirable that the joint be air and water tight. For example, when pulling fiber optic cable through a conduit, it is a common practice to use air pressure to first blow a fine fish-string through the pipeline. Also, where electrical wire or fiber optic cable is located inside the pipeline, the pipeline joints need to prevent infiltration of ground water. In similar fashion, well casing applications need to prevent infiltration of percolated surface water that potentially contains contaminants. Municipal water and sewer lines must also remain water-tight for most usable applications. The “restrained joint” helps to maintain the sealing integrity of the coupled lengths of pipe in such pipelines. In the area of well casings and directional drilling applications using PVC pipe, one approach has been to use axially aligned circumferential grooves machined into the mouth region of the belled pipe end and into the exterior surface of the mating male, spigot pipe end. A port is drilled through the female bell to complete a circumferentially shaped, canal type passageway for receiving a locking key strap which is subsequently passed through the bell wall, into the canal of the aligned grooves, and around the circumferential passageway. A number of different variations of this general concept are known in the marketplace at the present time. For example, U.S. Pat. No. 6,086,279 describes the equipment used in a manufacturing process for machining grooves into the inside surface of the female bell member of a plastic pipe coupling. U.S. Pat. No. 6,352,288 shows another mechanical pipe connection that includes the feature of coupler recesses with cooperating locking grooves on the pipes. Other patents representative of the general state of the prior art describe various purported improvements to these basic concepts, while sharing the common element of machining one or more grooves into the inner mouth region of the belled pipe end. U.S. Pat. No. 7,845,686, assigned to the assignee of the present invention, describes a cooperating casing member and sealing member individually placed on a Rieber bellling mandrel. The patent cites advantages of this arrangement, for example, different seal designs can be placed in cooperation with the same casing design. The male and female pipe ends used in the system each have aligned circumferential grooves which form a canal for passage of a locking key strap. During manufacture, the female belled end is sequentially formed over a Rieber style gasket and then over a ring-shaped casing member having an inner circumferenti