More particularly the invention relates to elastomeric jointing rings for providing a seal in a pipe joint of the spigot and socket kind.

It is to be understood that the expression"pipe"as used herein is intended to include pipes and tubes as such, and also pipe-like fittings used within pipework such as elbows,'T'bends and similar fittings, and also other elements such as valves incorporated in pipework and having parts of a pipe-like nature.

Joints of the above-mentioned kind are utilised in the inter-connection of pipes of water or gas carrying capability, for example, and comprise a socket at one end of a pipe having a recess within which is located an elastomeric jointing ring, which is sealingly engageable with a spigot of the next adjacent pipe on insertion into the socket so as to provide a sealed joint.

It is an object of the present invention to provide a simple and effective form of jointing ring for pipes, and a pipe joint incorporating such a jointing ring.

In accordance with a first aspect of the present invention, there is provided a jointing ring for a spigot and socket pipe joint comprising a sealing body of elastomeric material adapted in use to be located in and to fil. at least a substantial part of an appropriately shaped annular recess in

a pipe socket, a nose part of the sealing body having a radially inner surface generally parallel with the pipe axis, and being arranged for disposition in use at the mouth end of the socket, a resilient holding ring in an annular groove in a radially inner wall of the sealing body and exerting a radially outwardly-directed force on the sealing body such as to urge the sealing body to expand radially and thereby retain the sealing body in the annular recess of the pipe socket to which the sealing member is fitted for use, and an annular sealing part integral with and extending inwardly from the sealing body adapted to engage a spigot entered into the socket for sealing therewith.

In accordance with a second aspect of the present invention, there is provided a spigot and socket pipe joint in which the socket has an annular recess around its inner surface, and a jointing ring in accordance with the foregoing first aspect of the present invention is disposed between the spigot and socket, the sealing body of the jointing ring filling at least a substantial part of the annular recess, the annular sealing part of the jointing ring engaging and sealing the spigot within the socket, and the radially outwardly-directed force exerted by the resilient holding ring of the jointing ring on the sealing body retaining the sealing body in the annular recess of the socket.

Preferably the resilient holding ring is in the form of a spring, more particularly a clock spring or the like being of spring metal strip or ribbon spirally wound into a coil. The spring may have 1 to 2 turns, or possibly more. In a preferred form the spring is coiled from a length 11/2 to 2 times the circumference at the base diameter of the annular groove into approximately llh turns and then the outer turn is re-positioned inside the coil so as to contract the coil and so pre-load it for exerting the

required radially outwardly-directed force on the sealing body when the spring is located in the annular groove.

The spring is coiled to be oversize for the internal diameter of the annular groove. Typically it is 10 to 15% oversize.

The outward force exerted on the sealing body may be tuned to requirements of use by adjustment of material gauge, diameter and length of the spring. Preferably the outward force is such as to provide substantial resistance to detachment of the sealing body from the annular recess when the pipe work in which the jointing ring is fitted is in use, and also to detachment by hand or tools.

Pipes with which the jointing ring is used may be made of various materials e. g. plastics or fibreglass, and may take various forms e. g. cylindrical with a parallel bore.

The jointing ring may be adapted for use with spigot and socket pipe joints of various shapes and dimensions.

The sealing body of the jointing ring may comprise any suitable elastomeric material such as rubber or a mouldable polymeric material.

The annular sealing part of the jointing ring may comprise a spigot sealing flap positioned on the sealing body at the axially inner side of the holding ring and arranged such as in use of the jointing ring to be inclined axially inwardly of the socket in which the jointing ring is located.

The resilient holding ring ensures that the jointing ring is held securely in position in the socket during and after make-up of the joint. It

may be located in the recess manually so that costly assembly machinery can be avoided. Production of the jointing ring may thus be simplified and kept low in cost.

An embodiment of the invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a sectional view showing a jointing ring in accordance with the invention in a socket and spigot pipe joint, the spigot being shown only partially inserted, Figure 2 is an enlarged fragmentary sectional view of part of the jointing ring, and Figure 3 is a plan view of two conditions of a clock spring included in the jointing ring.

Referring to Figure 1 of the drawings, a jointing ring 1 comprises an annular sealing body 2 formed of an elastomeric material such as natural or synthetic rubber having a radially outer wall 3 engaging and filling a recess or seal housing 4 in the wall of the socket end 5 of a first pipe 6.

On the radially inner wall of the jointing ring, extending from the sealing body 2, is an inclined annular sealing flap 7 extending towards the axially inward part of the ring.

Extending axially outwardly away from the sealing flap 7 is a nose part 8 of the sealing body 2 which has an internal wall 9 of a cylindrical configuration. In the internal wall 9 adjacent to the root of the sealing

flap 7 is an annular groove 10. The annular recess 10 is conveniently in accordance with the standard retaining groove often provided in a jointing ring for a spigot and socket pipe joint.

Located in the annular groove 10 is a resilient holding ring 11 which, as shown in Figure 3, if in the form of a clock spring made from flat metal, preferably stainless steel, strip spirally wound into a coil. The strip is of complimentary width to the width of the recess axially of the jointing ring, Figure 2, and typically is wound into 11/2-2 turns. It is formed from a length of strip 11/2-2 times the circumference of the annular groove 10 at its base diameter and is initially rolled and coiled, as indicated at X in Figure 3, to be about 10-15% over-size relative to the base diameter of the annular recess 10 at its outer turn. Subsequently that turn is re-positioned inside the coil, as indicated at Y in Figure 3, so that the spring is then contracted and compressively pre-loaded. When spring is inserted into the recess in that pre-loaded state it exerts substantial outwardly-directed force on the sealing body 2 which urges the sealing body to expand.

In operation of the invention the jointing ring 1 is located within the seal housing 4 within the socket 5 of the first pipe 6 such that the radially outer wall 3 of the jointing ring 1 mates upon the inner surface of the seal housing 4. Location of the holding ring 11 in the annular groove 10 of the sealing body 2 urges the sealing body to expand radially and so tightly engage with substantial force against the inner surface of the seal housing 4. The location of the jointing ring 1 within the seal housing 4 is thus assured and securely retained by means of the holding ring 8. Having located the jointing ring to the seal housing a spigot 12 of a second pipe 13 to be jointed to the first pipe 6 is then inserted into the socket 5. It will be seen that the nose part 8 of the sealing body 2 of the

jointing ring 1 is chamfered 14 at its tip to ease access of the incoming spigot 12 into the socket 5. As it is inserted, the spigot 12 first of all lightly engages the inner wall 9 of the nose part 8 of the jointing ring 1 before engaging and bending the sealing flap 7 radially outwardly and axially inwardly so as to form a seal between the socket 5 and the spigot 12. Any tendency of the sealing flap 7 to turn the jointing ring 1 within the seal housing 4 in the socket 5, or to move the jointing ring 1 axially from its location in the seal housing 4 is firmly resisted by the tight and secure location of the sealing body 2 in the seal housing 4 of the socket 5.

By means of the invention we have provided a jointing ring and a pipe joint incorporating such a jointing ring, the jointing ring being able to be positively located in the seal housing 4 of the socket in its correct disposition within the joint before and during after the introduction of the spigot by the secure retention afforded by the use of the holding ring.

It will be appreciated that a known jointing ring having a retaining groove in its internal wall may be brought into accordance with the present invention by location of a resilient holding ring in the groove such as to urge the sealing body of the ring to expand.