GB2211255A

GB2211255A - Pipe joints and pipe couplings

Info

Publication number: GB2211255A
Application number: GB8823943A
Authority: GB
Inventors: Nicholas Lewis
Original assignee: Victaulic Co PLC
Current assignee: Victaulic Co PLC
Priority date: 1987-10-16
Filing date: 1988-10-12
Publication date: 1989-06-28
Anticipated expiration: 2008-10-12
Also published as: GB2211255B; GB8724335D0; GB8823943D0

Abstract

A coupling for,and a joint between, the ends of two pipes wherein the end of each pipe is shaped to provide a radially outwardly extending shoulder adjacent to the pipe end, and a tapering portion of the outer surface of the wall pipe tapering radially inwardly from at or adjacent the shoulder towards the pipe end; an annular sleeve-like housing split by at least one axially extending slit and having at each axial end thereof a radially inwardly extending annular protrusion engagable behind the shoulders on the pipes; fastening means secured across the or each slit; and an annular sealing gasket located within the housing and compressed radially inwardly by the inner peripheral wall thereof, the sealing gasket having lips extending from each axial end thereof in a radially and axially inward inclined direction so as to abut and seal upon the tapered outer surface of the pipe wall.

Description

Pipe Joints and Pipe Couplings This invention relates to pipe joints and couplings for pipes.

By the expression pipes as used herein is meant pipes and tubes as such, as well as pipe-like members and fittings for use in pipework such as bends, elbows, "T" connectors and parts of devices fitted into pipework such as valves and pumps.

It is known to provide a pipe joint utilising a coupling in which the ends of two pipes to be connected are each provided either with a shoulder at its end (which may be formed by an expanded end, a turned back end or a thickened end) or a groove adjacent the end which, when taken with the end portion of the pipe, is the physical equivalent of a shoulder. The groove may be formed by cutting or by deforming the metal such as by rolling.

A joint between two such prepared ends of pipes may be made by means of a coupling comprising an annular axially segmented sleeve-like housing having inwardly radially extending end walls which are fitted behind the shoulder or within the groove (as the case may be) of the end of each of the two pipes with an annular sealing member located between the housing and the ends of the pipes. The segments of the housing are then fastened and tightened together.

The annular sealing member used in couplings of this kind may function both as a compression seal, and also a lip seal by having returning lips which bear against the annular outer periphery of the end portions of each of the pipes, a space radially outwardly from the lips being accessible to fluid from within the pipes so that the pressure within the pipes acts upon and increases the sealing effect of the returned lips.

Couplings of this kind which utilise a sealing member of the form just discussed do require a substantial radial dimension to operate satisfactorily with both compressive and pressure responsive lip sealing functions.

This can lead to the joint having an undesirably high profile increasing the space required for a pipework system incorporating such joints, and increasing the weight of the couplings and, hence, the pipework.

It is an object of the present invention to overcome or at least sunbstantially reduce the above mentioned problem.

In accordance with one aspect of the invention there is provided a joint between the ends of two pipes wherein the end of each pipe is shaped to provide a radially outwardly extending shoulder adjacent the pipe end, and a tapering portion of the outer surface of the wall of the pipe tapering radially inwardly from at or adjacent the shoulder towards the pipe end; an annular sleeve-like housing split by at least one axially extending slit and having at each axial end thereof a radially inwardly extending annular protrusion engageable behind the shoulders on the pipes; fastening means secured across the or each slit; and an annular sealing gasket located within the housing and compressed radially inwardly by the inner peripheral wall thereof, the sealing gasket having lips extending from each axial end thereof in a radially and axially inward inclinded director so as to abut and seal upon the tapered outer surface portion of the pipe wall.

The end of each pipe may be shaped by working so as to form the radially outwardly extending shoulder.

The tapering portion of the outer surface of the wall of the pipe may taper at any convenient angle to the longitudinal axis of the pipe and housing appropriate for the dimensions and configuration of the joint and housing.

Thus, whilst with some configurations an angle of the order of 300 is appropriate, with other configurations the angle, for satisfactory sealing by the gasket, may be as little as 0.50.

The ends of the pipes in the pipe joint of the invention may be pre-prepared to their required configuration by machining, or in an alternative the pipe ends may be subjected to a rolling operation circumferentially provide the required outwardly extending shoulder and tapered portion. Other techniques may include mill pre-forming, expansion, for example.

In accordance with a further aspect of the invention there is provided a coupling for forming a joint between the ends of two pipes in which the end of each pipe is shaped to define a radially outwardly extending shoulder adjacent the end thereof, and a tapering portion of the outer surface of the wall of the pipe tapering radially inwardly from the shoulder towards the pipe end; the coupling comprising an annular sleeve-like housing split by at least one axially extending slit and having at or adjacent each axial end thereof a radially inwardly extending annular protrusion engageable in use with the shoulders on the pipes; fastening means securable across the or each slit; and an annular sealing gasket located within the housing and supported by the inner peripheral wall thereof, the sealing gasket having lips extending from each axial end thereof in a radially and axially inward inclined direction so as, in use, to abut and seal upon the tapered outer surface portions of the pipe walls.

The housing may, with joints and couplings of small to moderate size, be comprised by a single segment split by a single axially extending slit and made capable of tightening about the pipes to be joined on assembly by means of the fastening means connecting across the slit.

Such fastening means may conveniently comprise appropriate nuts and bolts fitting within bores in lugs adjacent each side of the axial slit. In an alternative, a toggle or latch arrangement can be used.

For larger sized joints, e.g. joints above approximately 12in internal diameter a plurality of segments and fastening means may be provided.

The housing may, in its axial direction, be gently domed and accommodate within it a similarly domed elastomeric sealing gasket. Alternatively, the housing may be of right cylindrical sleeve-like configuration between the two radially inwards extending shoulders, and the gasket contained therewithin may similarly be provided with a right cylindrical outer surface.

By means of the invention, and in particular because of the mating axial radially inwardly inclined surfaces of the gasket and the pipes, satisfactory operation, both in compressive sealing and lip sealing can be achieved with a coupling housing of less radial magnitude, so that a lower profile and hence lighter coupling can be provided.

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 elevation of part of a first embodiment of the coupling and pipe joint in accordance with the invention; Figure 2 is a cross-section of the sealing ring of the arrangement of Figure 1 in a relaxed condition; Figure 3 is an isometric view of part of the coupling of the joint of Figure 1; Figure 4 is a sectional elevation of part of a second embodiment of a coupling and pipe joint in accordance with the invention; Figure 5 is a cross-section of the sealing ring of the arrangement of Figure 4 in a relaxed configuration.

Figure 6 is a part sectional side elevation of a third embodiment of a coupling in accordance with the invention; Figure 7 is a part sectional front elevation of the coupling of Figure 6; Figure 8 is an isometric view of part of the coupling of Figure 6 in a separated condition; Figure 9 is an isometric view of the sealing gasket of the coupling of Figure 6; Figure 10 is an enlarged sectional front elevation of part of the gasket of Figure 9; and Figure 11 is a cross-section of a modification of the gasket of Figure 9.

Referring now to Figures 1, 2 and 3 of the drawings, it will be seen that the pipe joint includes the ends of two pipes 1, 2, which may be formed of steel or similar material, which have been prepared by circumferential rolling so as to define, in each case, a shoulder 3, 4 adjacent the end of the pipe extending radially outwardly of the pipe, leading to an inwardly tapered end portion 5, 6 of the outer peripheral wall thereof (at an angle of the order of 300 to the longitudinal arm of the joint), and a coupling 7 located about the shoulders and tapered portions of the two pipes. The coupling comprises a sleeve-like housing 8 of segmented annular configuration.

It is to be seen from Figure 3 that, in this case, the housing is constituted by a single segment split by a single axially extending slit 9. The housing may be formed of a malleable material which may be of malleable iron, ductile iron, aluminium, plastics or steel, for example, and has a protrusion or shoulder 19, 20 extending radially inwardly at each end.

Lugs 10, 11 are provided on the housing 8, one on each side of the axial slit 9, the lugs being adapted to receive fastener means comprising a bolt 12 and a nut 13.

The bolt may be provided with a shaped neck beneath its head (not shown) adapted to locate within an appropriate shaped bore in the associated lug 10, thereby preventing rotation of the bolt 12 on tightening the nut 13.

It is to be noted that, in this particular embodiment, the housing 8 is, in axial cross-section, of a shallow configuration with a gently domed shape.

Within the housing is an elastomeric sealing ring or gasket 14 conforming to the shape of the housing 8 and having, from each of its axial ends, sealing lips 15, 16 which incline radially and axially inwardly so as to abut against the tapered portions 5, 6 of the pipes. It will be seen from Figure 2 that, in its relaxed condition, the lips of 15, 16 of the sealing ring 14 are more radially inwardly protruding than when disposed within the joint in the fully tightened condition shown in Figure 1. Hence, the sealing ring 14 operates as a compression sealing member and, in addition, the two lips 15, 16 under action from the fluid contained within the pipes, act as an internal pressure dependent sealing arrangement. As shown in Figure 2, the underside of each of the lips may be provided with a plurality of circumferential ribs 17, 18 to improve the sealing effect.

The coupling 7 from which the joint of Figure 1 is assembled may be supplied to the user in a pre-assembled condition with the sealing ring 14 located within the housing 8, and with the nut 13 and bolt 12 fastenings loosely positioned. In this condition, one pipe 1 can be pushed into the coupling 7 until shoulder 19 of the housing is behind the shoulder 3 on the pipe and the appropriate sealing lip 15 of the sealing ring is in contact with the tapered portion 5 of the pipe ends. The second pipe 2 is then inserted into the open end of the coupling 7 again until its shoulder 4 is fully in position behind the shoulder 20 of the housing. In this condition, the sealing ring 14 is in direct contact with both pipe ends within the housing.The nut and bolt fastening 12, 13 is then tightened until the lugs 10, 11 of the housing are in contact with each other so that the axial slit 9 is closed. At this point, the tolerances of the arrangement are such that the internal diameter of the housing shoulders 19, 20 is in partial or total contact with the outside diameter of the pipes 1, 2.

The arrangement of Figures 4 and 5 is the same as that of Figures 1, 2 and 3 except that, in this case, the housing has a right cylindrical section 21 axially within inwardly extending shoulders 22, 23 and the elastomeric sealing ring has a like configuration of its outer wall 24.

A further modification of joint and coupling according to the invention is illustrated in Figures 6 to 10. In this modification, the housing 25 is in the form of two segments 26, 27 connected together at one side, as best shown in Figure 8, by means of a latch comprising a hook-like protrusion 28 from one segment 26 engageable within appropriately shaped slots 29 and ribs 30 at the end of the other segment 27.

Diametrically opposite to the latch lugs 31, 32 are provided at the opposed ends of each segment 26, 27 by means of which the coupling may be securely clamped together by means of a bolt 33 and nut 34 passing through bores in the lugs.

As can be seen from Figure 9, the sealing gasket of this embodiment is in the form of a slit moulded gasket 35 having additional rubber 36 adjacent and within the lugs of the segments. In addition, as can be seen in Figure 10, a lip seal 37 is provided at the inner periphery of the gasket adjacent the mutually engaging faces 38 thereof alongside the lug portions 36 of the gasket so as to ensure secure sealing at this portion of the gasket.

As can be seen in Figure 6, the cross-section of the gasket 35 of this embodiment is somewhat different from the gaskets illustrated in Figures 2 and 5, in that the overall angle of inclination of the lips 39 is considerably less, and additionally there is a portion 40 without inclination to mate with a "flat" on the relevant pipe shoulder (not shown) It will be appreciated that with a coupling of the configuration illustrated, and with the angle of inclination of the lip seal portions 39 of the gasket 35 of the low order of magnitude as shown, the corresponding inclined surfaces of the pipes to be inserted into the coupling (not shown) can be much lower than those shown in Figures 1 and 4, and can even be as low as 0.50.

The latch mechanism for securing together the two segments of the coupling may be formed by pressing moulding or casting the relevant segments. This latch arrangement enables the coupling to fit together to form a strong hinged joint.

The configuration of the split gasket illustrated in Figure 9, moulded in elastomeric material of suitable form, is, as has been noted, formed in such a way as to seal all around the pipe circumference when clamped within the housing.

The advantages of the arrangement of Figures 6 to 10 is that there is a considerable ease of fitting, especially on existing pipework where the need to move pipes apart is obviated in view of the hingable nature of the coupling which can be, therefore, fitted over the pipes in their fixed position. Again, permanent location of the sealing gasket within the housing obviates the need to place the latter onto the pipe ends prior to fixing the joint. The whole assembly can be placed over the pipe ends and tightened by the nut and bolt shown. It is to be noted that the large volume of sealing material within the abutting lug parts of the coupling, when under compression, enables a sound seal to be formed at the contact faces of the gasket.

A variation of the gasket of the embodiment of Figures 6 to 10 is illustrated in Figure 11. As can be seen, the gasket 41, shown in section, has a centre rib 42. This may be a solid circumferential rib, or may be formed of a plurality of projections displaced uniformly around the inner surface of the gasket.

The rib or projections help to prevent a pipe end from "pushing" through the gasket past its optimum operational position during assembly of the joint. In assembly a pipe end is inserted into the joint and makes contact with one side of the rib. This prevents any further passage through the ring. A second pipe is then inserted from the other side of the coupling in a similar manner.

Additionally, the gasket 41 is provided with different angled portions 43, 44 of the sealing lips 45 to allow the leading edge to "spring" on to the outer periphery of a pipe inserted into the coupling.

The coupling and joint as herein described permits a considerable degree of angular misalignment of juxtaposed pipes while still maintaining a fully secure sealed joint, pipe end load is adequately restrained, the coupling may be easily and quickly fitted to pipe ends, and can be assembled on the pipe ends without any dismantling.

Additionally, a low profile and, therefore, reduced weight of the coupling housing can be provided by arranging for the lip seal to be on inwardly inclined surfaces of the pipe ends. The arrangement of Figures 4 and 5 provides an even lower profile.

With the embodiments illustrated, there is improved access during assembly with only one fastening device requiring attention.

It will be understood that the present invention has been described above purely by way of example and modifications of detail can be made within the scope of the invention.

Claims

CLAIMS:

1. A joint between the ends of two pipes wherein the end of each pipe is shaped to provide a radially outwardly extending shoulder adjacent to the pipe end, and a tapering portion of the outer surface of the wall pipe tapering radially inwardly from at or adjacent the shoulder towards the pipe end; an annular sleeve-like housing split by at least one axially extending slit and having at each axial end thereof a radially inwardly extending annular protrusion engagable behind the shoulders on the pipes; fastening means secured across the or each slit; and an annular sealing gasket located within the housing and compressed radially inwardly by the inner peripheral wall thereof, the sealing gasket having lips extending from each axial end thereof in a radially and axially inward inclined direction so as to abut and seal upon the tapered outer surface of the pipe wall.

2. A joint as claimed in Claim 1 wherein the end of each pipe is shaped by working so as to form said radially outwardly extending shoulder.

3. A joint as claimed in Claim 2 wherein the ends of the pipes are pre-prepared to the required configuration by machining.

4. A joint as claimed in Claim 2 wherein the pipe ends are subjected to a rolling operation circumferentially to provide the required outwardly extending shoulder and tapering portion.

5. A joint as claimed in any one of the preceding claims wherein the housing is comprised by a single segment split by a single axially extending slit capable of tightening about the pipes to be joined on assembly by means of the fastening means connecting across the slit.

6. A joint as claimed in any one of Claims 1 to 4 wherein the housing is comprised by two segments connectable on one side by means of a latch mechanism, and having# on the other side an axially extending slit capable of tightening upon the pipes to be joined on assembly by means of a fastening means connecting across the slit.

7. A joint as claimed in any one of the preceding claims wherein the annular gasket is provided with at least one slit adapted in use to coincide with the or each slit in the housing.

8. A joint as claimed in any of the preceding claims wherein the housing is, in its axial direction, domed and accomodates within it a similar domed elastomeric sealing gasket.

9. A coupling for forming a joint between the ends of two pipes in which the end of each pipe is shaped to define a radially outwardly extending shoulder adjacent the end thereof, and a portion of the outer surface of the wall of the pipe tapering radially inwardly from the shoulder towards the pipe end; the coupling comprising an annular sleeve-like housing split by at least one axially extending slit and having at or adjacent each axial end thereof a radially inwardly extending annular protrusion engagable in use with the shoulders on the pipes; fastening means securable across the or each slit; and an annular sealing gasket located within the housing and supported by the inner peripheral wall thereof, the sealing gasket having lips extending from each axial end thereof in a radially and axially inward inclined direction so as, in use, to abut and seal upon the tapered outer surfaces of the pipe walls.

10. A pipe coupling substantially as shown in and as hereinbefore described with reference to the accompanying drawings.

11. A pipe joint substantially as shown in and as hereinbefore described with reference to Figure 1 or Figure 4 of the accompanying drawings.