GB2251280A

GB2251280A - Pipe joints and gaskets therefor

Info

Publication number: GB2251280A
Application number: GB9028190A
Authority: GB
Inventors: Nicholas Grant
Original assignee: Victaulic Co PLC
Current assignee: Victaulic Co PLC
Priority date: 1990-12-29
Filing date: 1990-12-29
Publication date: 1992-07-01
Anticipated expiration: 2010-12-29
Also published as: GB9028190D0; GB2251280B

Abstract

A spigot and socket joint has a gasket 6 of single hardness resilient material having a nose 7 engaging the inner wall of the terminal flange 5 of socket 1, and a peripheral slot engaging annular protrusion 4 in socket groove 3, said gasket having an internal diameter at its nose 7 of the same general magnitude as the internal diameter of the terminal flange 5, and the main body of the gasket 6 being bifurcated, the radially outer part 9 tapering axially inwardly and, when relaxed, lying on or adjacent the groove base, and the radially inner part 10 tapering axially inwardly and being inclined radially inwardly into the socket so as to have a decreasing internal diameter less than that of the terminal flange, the inner surfaces 21, 22 of the bifurcated outer part and inner parts merging smoothly one with the other. <IMAGE>

Description

Pipe Joints and Coupling and Parts Therefor This invention relates to pipe joints and couplings and parts therefor, and more particularly relates to spigot and socket joints between two adjacent pipes, and annular sealing members or gaskets (located in use in an internal annular groove around the socket) for such pipe joints.

It is to be understood that the socket portion of the joint may be comprised by a sleeve member open at both ends and having a socket portion at both ends, into which double spigot ended pipes are inserted for connection, although with the particular pipe joint type to which the invention is especially applicable such an arrangement of separate socket couplings is not usually used.

Additionally it is to be understood that the expression "pipes" as used herein means pipes and tubes as such and also pipe-like members and fittings for use in pipe works such as bends, elbows, "T" connectors and parts of devices adapted to be fitted into pipe work, such as valves and pumps.

The invention is especially concerned with the type of spigot and socket pipe joint known as "TYTON" (Registered Trade Mark).

In a TYTON pipe joint (hereinafter referred to as "a joint of the type described"), the socket carries around its radially inner wall adjacent its open mouth, a groove immediately behind a radially inwardly extending terminal flange, the groove being provided around its inner periphery with a curved section inner protrusion between a quarter and a third of the distance along the grooves' length axially inwardly of the socket.

Additionally, the groove is provided with an annular gasket, usually in two parts of separate hardness resilient material adapted to be seated within the groove behind the inwardly projecting annular flange, and, by means of an appropriate annular slot in its outer periphery, over the radially inner annular protrusion. In practice the protrusion engages in the gasket some one third down the gaskets' axial length, and the gasket is of such dimensions that its inner diameter is, in its relaxed state, substantially less than the inner diameter of the terminal flange of the socket.As stated, the gasket is usually of dual hardness, the harder portion being adjacent the axially outer end, or nose, thereof approximately from its position of engagement with the protrusion, to the engagement thereof with the inwardly directed terminal flange, whilst the softer portion of the gasket is comprised by the remaining two thirds, or main body, which extend, in lozenge-like configuration in section, in its relaxed state, axially inwardly of the joint, and radially inwardly of the internal diameter of the socket whilst abutting along its outer surface on the base of the groove around the socket.

In the formation of a joint of the type described, a pipe spigot is inserted into the open end of the socket and firstly bears upon the harder portion of the gasket where it is located behind the terminal flange of the socket, upon the base of the groove, and upon the protrusion thereof, the radially outwards compressive force from the spigot firmly and positively locating the nose of the gasket against any sliding within or turning movement out of the groove of the socket. Further movement of the spigot into the socket brings about engagement of the outer periphery of the spigot with the softer main body, portion of the gasket which is thereby compressed radially outwardly between the spigot and the socket to perform a satisfactory sealing function.

Pipe joints of this kind have been very widely used over several decades primarily because they have been found to be extremely reliable safe joints for use in carrying various gases and liquids at high pressure. Not only have the sealing properties been adequate for the requirements put upon the joint, but the making of the joint has been most effective without significant risk of badly made joints caused by movement of the gasket during make-up.

One disadvantage of joints of the type described has been the desirability of using double hardeness rubber for the gasket because of its effectiveness in ensuring correct assembly of the joint without disturbance of the gasket, whilst still ensuring satisfactory sealing.

Various attempts have been made, in order to provide a cheaper joint, to use a single hardness rubber, but for one reason or another no previous effort hitherto has been totally satisfactory.

It is an object of the present invention to provide a pipe joint of the type described which overcomes earlier difficulties with single rubber gaskets, and also to provide a single rubber gasket for a pipe joint of the type described.

In accordance with one aspect of the present invention there is provided a spigot and socket joint of the type described incorporating a gasket of single hardness resilient material having a nose engaging with the inner wall of the radially inwardly directed terminal flange of the socket of the joint, and a peripheral slot around its outer surface for engaging with the radially inward annular protrusion of the socket groove, said gasket having an internal diameter at its nose of the same general magnitude as the internal diameter of the terminal annular flange of the socket, and the main body portion of the gasket being at its end axially inward from the socket mouth bifurcated, the radially outer part thereof tapering to adjacent the end of the groove and the radially outer surface of the outer part in its relaxed condition lying on or adjacent the groove base, and the radially inner part thereof tapering axially inwardly of the socket and being inclined radially inwardly into the socket so as to have a decreasing internal diameter less than that of the terminal annular flange, the inner surfaces of the bifurcated radially outer part and radially inner part merging smoothly one with the other.

Preferably the inner surfaces of the bifurcated radially outer part and radially inner part merge by means of a smooth curving surface which may be of wide diameter relative to the gasket width to ensure that the bifurcated outer part and inner part commence tapering from root portions of little thickness compared to that of the gasket as a whole. Thus, by way of an example, each outer part and inner part may have at its root a thickness between 20% and 30% of the thickness of the gasket at its nose, when in a relaxed configuration. The tapering outer part and inner part may each have generally flat inner and outer surface and end in "feather" edges.Such a configuration has been found by the applicants to provide excellent flexibility at the bifurcated part and surprisingly good sealing properties, whilst the remainder of the gasket provides exceptionally secure location thereof in the socket.

In accordance with another aspect of the present invention there is provided a gasket of single hardness resilient material for a spigot and socket joint of the type described incorporating a nose for engagement, in use, with the inner wall of the radially inwardly directed terminal flange of the socket of the joint, and a peripheral slot around its outer surface for engaging, in use, with the radially inward annular protrusion of the socket groove, the gasket having an internal diameter at its nose arranged to be of the same general magnitude as the internal diameter of the terminal annular flange of the socket, and the main body portion of the gasket being at its end axially inward from the socket mouth bifurcated, the radially outer part thereof tapering to its end and configured such that, in use, its radially outer surface in its relaxed condition lies on or adjacent the groove base, and the radially inner part thereof tapering to its end and being inclined radially inwardly into the socket so as to have a decreasing internal diameter, the inner surfaces of the bifurcated radially outer part and radially inner part merging smoothly one with the other.

By means of the invention on insertion of a spigot into a socket, positive location of the gasket is provided by compression by the spigot of the nose of the gasket against the terminal inward flange, the base of the socket groove, and round the radially annular protrusion of the socket groove, and sealing is provided at the rear of the gasket both by means of compression of the tapered bifurcated portions, and internal pipe pressure energisation.

The gasket of the joint of the present invention may have an overall single hardness between the severe hardness previously used at the nose of the gasket of the joint of the type described and the soft nature of the main body thereof, although the general hardness and resilience of the gasket will be chosen in dependence upon the particular requirements and circumstances of the usage of the joint of the type described.

The applicants appreciate that it is known to provide gaskets having a compressive nose for combined sealing and location purposes, and a "feather edge" sealing portion behind that nose for both compression and internal pressure energised sealing. However they have appreciated for the first time that with an appropriate and special design of gasket such an arrangement can be used extremely effectively in pipe joints of the type described, so that a less expensive single hardness gasket can be used with great efficacy.

Joints of the type described are typically not joints in which the spigot is locked within the socket, although various arrangements have been provided to give the joint a locked characteristic.

This can be done with the present invention by, for example, incorporating into the gasket a plurality of metal inserts around its periphery which may, for example, engage at least partly around the protrusion at the bottom of the groove of the socket and with the inner surface of the terminal flange, and which may protrude to the radially inner surface of the gasket and have at least one tooth arranged to lie adjacent the surface of the gasket at the radially inner surface such that, after insertion of a spigot into a socket causing compression of the gasket and sealing from the main body portion thereof, the tooth or teeth of each of the metal inserts engages or nearly engages the outer periphery of the spigot.Any attempt to remove the spigot will tend to rotate each of the metal inserts about the protrusion at the bottom of the groove in the inner wall of the socket so that the tooth or teeth tend to project further inwardly into the socket and engage sharply with the outer periphery of the spigot, and thereby prevent removal of the spigot.

In order that the invention may be more readily understood, two embodiments thereof will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a sectional side elevation of part of a joint of the type described in accordance with the invention prior to assembly; Figure 2 shows the joint of Figure 1 in an assembled configuration; and Figure 3 shows a second embodiment of a joint of the type described in accordance with the invention in an assembled condition.

Referring now to Figure 1, it will be seen that the joint is of the type described and comprises a socket 1 of known form formed integrally on the end of a pipe 2. The socket 1 has an annular groove 3 running around the inner wall thereof and has on its base a protrusion 4, generally semicircular in section, approximately between a quarter and one third of the distance along the groove 3. The groove is closed at the front open end of the socket by a radially inwardly extending terminal flange 5 which additionally consitutes the axially front wall of the groove.

Disposed within the groove in the socket is an annular gasket 6 having a solid nose portion 7 substantially filling the groove up to and behind the annular protrusion 4 from the base of the groove. The radially inner wall 8 of the gasket has, at its axially front end, an internal diameter corresponding generally to that of the internal diameter of the terminal flange of the socket. The wall 8 tapers axially and radially inwardly therefrom. Axially behind the protrusion 4, the gasket 6 is bifurcated and has two tapered arms 9 and 10, the radially outer one 9 of which seats upon the base of the groove 3, whilst the inner one 10 of which extends substantially into the volume of the socket.

The inner surfaces 21,22 of the bifurcated radially outer part 9 and radially inner part 10 merge by means of a smooth curving surface 23 which has a wide diameter relative to the gasket width to ensure that the bifurcated outer part 9 and inner part 10 commence tapering from root portions 24,25 of little thickness compared to that of the gasket as a whole. Thus, by way of an example, each outer part and inner part has at its root a thickness between 20% and 30% of the thickness of the gasket at its nose 7, when in a relaxed configuration. The tapering outer part and inner part each have generally flat inner and outer surface and end in "feather" edges.

The gasket is of a single hardness resilient synthetic rubber material.

Upon insertion of a spigot 11 into the socket as shown in Figure 2, it will be seen that the nose portion of the gasket 6 is compressed into the groove 3 such that its nose is held firmly in place by the terminal flange 5 of the socket, the base of the groove 3, and the semicircular protrusion 4 on the base of the groove 3, so that the gasket is firmly held against any significant risk of sliding or turning axially inwardly of the socket upon continuing frictional strain applied by the external periphery of the spigot as it is moved to its full engagement position within the socket with its nose 12 abutting a rear shoulder 13 of the socket.

As it passes the inner tapered arm 10 of the gasket, the spigot 11 compresses this radially outwardly, and by its resilient linkage to arm 9, similarly compresses this one outwardly so as to form a seal by the arms between the spigot and the socket. In addition in use, with a fluid under pressure disposed within the pipework system and within the joint, it is to be noted that the pressure from the contained fluid bears upon the tapered arms 9 and 10 of the gasket 6 providing an even better pressure energised seal with the inner wall of the socket and the outer peripheral wall of the spigot.

The embodiment of the invention illustrated in Figure 3 shows essentially the same configuration of socket and spigot and gasket, except that in this case a plurality of metal inserts 14 have been embedded around the periphery of the gasket 15, each insert being so shaped that a nose portion 16 thereof fits into the corner between the base of the groove 3 and the axially inner wall of the terminal flange 5 of the socket, the wall 17 of each insert 14 transverse to the axis of the socket being inclined to the inner axial wall 18 of the terminal flange.

In addition the insert is shaped so as to curve around the protrusion 4 in the base of the groove 3.

Additionally each groove has two teeth 19, 20 at the radially inward edge thereof which lie at or closely adjacent to the inner peripheral wall of the gasket 15.

Insertion of the spigot 11 into the socket 1 with such a modified gasket in position acts substantially as described with reference to Figure 2 except that some engagement between the teeth 19, 20 of the insert and the outer wall of the spigot 11 will occur. If subsequently an attempt is made to remove the spigot 11 by pulling it from the mouth of the socket, the teeth 19, 20 will bite into the outer periphery of the wall of the spigot, and turn slightly the insert about the protrusion 4 until its wall 14 transverse to the axis of the socket lies tightly alongside the equivalent axially inner wall 18 of the terminal flange 5. In this disposition, the engagement of the teeth with the spigot peripheral wall is of such strength that the spigot is successfully restrained from movement out of the socket.

The applicants have found that with the gasket of each embodiment of the invention illustrated, excellent positive location of the gasket in the joint is ensured with remarkably good resistance to any disturbing force, and that in addition the flexibility of the bifurcated parts and their configuration provides surprisingly effective sealing properties.

By means of the invention the applicants have provided a satisfactory joint of the type described with a fully sufficient and proficient gasket of single hardness resilient material, and a gasket for such a joint.

Indeed the gasket can readily be fitted into standard "TYTON" (Registered Trade Mark) sockets without alteration of the configuration of the sockets.

It is to be understood that the foregoing is merely exemplary of pipe joints and gaskets therefor in accordance with the invention and that modifications can readily be made thereto without departing from the true scope of the invention.

Claims

CLAIMS:

1. A spigot and socket joint of the type described incorporating a gasket of single hardness resilient material having a nose engaging with the inner wall of the radially inwardly directed terminal flange of the socket of the joint, and a peripheral slot around its outer surface for engaging with the radially inward annular protrusion of the socket groove, said gasket having an internal diameter at its nose of the same general magnitude as the internal diameter of the terminal annular flange of the socket, and the main body portion of the gasket being at its end axially inward from the socket mouth bifurcated, the radially outer part thereof tapering to adjacent the end of the groove and the radially outer surface of the outer part in its relaxed condition lying on or adjacent the groove base, and the radially inner part thereof tapering axially inwardly of the socket and being inclined radially inwardly into the socket so as to have a decreasing internal diameter less than that of the terminal annular flange, the inner surfaces of the bifurcated radially outer part and radially inner part merging smoothly one with the other.

2. A joint as claimed in Claim 1 wherein the inner surfaces of the bifurcated radially outer part and radially inner part merge by means of a smooth curving surface which may be of a large diameter relative to the gasket width to ensure that the bifurcated outer party and inner part commence tapering from root portions of little thickness compared to that of the gasket as a whole.

3 A joint as claimed in Claim 2 wherein each outer part and inner part may have at its roots a thickness between 20% and 30% of the thickness of the gasket at its nose, when in a relaxed configuration.

4. A joint as claimed in any one of the preceding Claims wherein the tapering outer part and inner part of the gasket may each have a generally flat inner and outer surface and end in "feather edges

5. A joint as claimed in any one of the preceding Claims wherein the gasket is of material having an overall single hardness between the severe hardness previously used at the nose of the gasket of the joint of the type described and the soft nature of the main body thereof.

6. A joint as claimed in any one of the preceding Claims wherein the gasket incorporates a plurality of metal inserts around its periphery engaging at least partly around the protrusion at the bottom of the groove socket and with the inner surface of the terminal flange, and protruding to the radially inner surface of the gasket and having at least one tooth arranged to lie adjacent the surface of the gasket with a radially inner surface.

7. A gasket of single hardness resilient material for a spigot and socket joint of the type described incorporating a nose for engagement, in use, with the inner wall of the radially inwardly directed terminal flange of the socket of the joint, and a peripheral slot around its outer surface for engagement, in use, with the radially inward annular protrusion of the socket groove, the gasket having an internal diameter at its nose arranged to be of the same general magnitude as the internal diameter of the terminal annular flange of the socket, and the main body portion of the gasket being bifurcated at its end axially inward from the socket mouth, the radially outer part thereof tapering to its end and configured such that, in use, its radially outer surface in its relaxed condition lies on or adjacent the groove base, and the radially inner part thereof tapering to its end and being inclined radially inwardly into the socket so as to have a decreasing internal diameter, the inner surfaces of the bifurcated radially outer part and radially inner part merging smoothly one with the other.

8. A spigot and socket joint substantially as shown in and as hereinbefore described with reference to the accompanying drawings.

9. A gasket of single hardness resilient material substantially as shown in and as hereinbefore described with reference to the accompanying drawings.