GB2377975A

GB2377975A - A gasket device for a pipe joint

Info

Publication number: GB2377975A
Application number: GB0118032A
Authority: GB
Inventors: Der Post Jan Rupert Van; Richard Wolfgan Mosse
Original assignee: HYJOIN Ltd
Current assignee: HYJOIN Ltd
Priority date: 2001-07-24
Filing date: 2001-07-24
Publication date: 2003-01-29
Also published as: GB0118032D0; WO2003010448A1

Abstract

A gasket device 1 for a pipe joint 3 between two pipe ends 9, the device 1 comprising: a gasket 5 for providing a seal between the two pipe ends 9, and a support structure 6 for receiving the gasket 5, wherein the support structure 6 includes gripping portions 7 which clip onto a pipe end 9 to locate the gasket 5 and acts as a stop to protect the gasket 5 during the closing of the pipe joint. The support structure 6 is manufactured in one piece and is preferably made of engineering plastics material which, together with a soft material (elastomeric) gasket 5, enables the accurate alignment and location of the gasket.

Description

A PIPE JOINT AND A GASKET DEVICE THEREFOR This invention relates to pipe joints, and in particular to an improved gasket device for a pipe joint.

Many types of gasket exist, the vast majority of which are manufactured from elastomeric materials. When fitting such gaskets between pipe ends of a pipe joint, it can be very difficult to keep the soft elastomer in position to ensure that it accurately forms a quality seal between the two pipe ends as the pipe ends are closed together. In practice, it is often impossible to tell whether the gasket is correctly aligned with the pipe ends following tightening of a pipe joint without first testing the integrity of the pipe joint by pressure testing the pipe bore itself. This is clearly time consuming and expensive.

The present inventors have been involved for some time in the field of hygienic food processing systems and joints for use in such systems, and have developed a number of gaskets and pipe joints such as disclosed in PCT/GB97/01332 (WO 97/44602), PCT/GB99/03050 (WO 00/17548) and PCT/GB01/01488 (not yet published) for example. These prior art gasket designs, which have proved extremely successful, have been directed towards gaskets manufactured from more rigid materials, preferably engineering plastics materials.

Such rigid materials include polyetheretherketone (PEEK), polyethersulfone (PES), TORLON (Trade Mark), ULTEM (Trade Mark), polyamide (such as VESPEL), polyetherimid and polycarbonates. The present invention, however, uses some of the technology developed by the present inventors, but applies it to pipe joints in which non-engineering plastics materials are used for the gasket itself. More particularly, the present invention relates to a gasket device for a pipe joint between two pipe ends wherein an elastomeric or other soft material gasket is supported and accurately aligned with a pipe bore by a rigid support structure. Such a gasket device assists considerably in the installation of a soft gasket and results in far fewer alignment failures as two pipe ends are brought together during closing of a pipe joint.

Prior art gasket devices are known from US-5340170 (Shinohara et a/) and EP-0837277. Both of these documents, however, relate to stainless steel or like material gaskets simply supported by a retainer for push fitting on to a pipe end.

They make no suggestion whatsoever that the gasket could be a soft material gasket, such as an elastomer, nor that the supporting structure (i. e. the retainer) is to be used as a stop to protect the gasket from excessive compression during closing of the pipe joint. Hence, these prior art documents do not address the same problem as that of the present invention, namely how to hold a soft material gasket in position on a pipe end during closing of a pipe joint whilst preventing the gasket being crushed or bulging into the product flow as the pipe joint is closed.

As mentioned above, the present inventors have been involved in the field of hygienic food processing systems. Such systems clearly require very strict controls on the materials which come into contact with the products passing through the pipeline. Since, in general, elastomeric or similar materials have been tested and found to be acceptable for hygienic processing of pharmaceuticals, it is preferably to be able to continue using such known materials on lines that have been validated by bodies such as the US Food and Drug administration as safe for the manufacture of a product and the present invention allows this. It will, however, be appreciated that the presented invention is not limited to hygienic pharmaceutical processing systems, but could be applied to many other pipe joints or similar arrangements.

In the light of the foregoing, the present invention provides a gasket device for a pipe joint between two pipe ends, the device comprising: a gasket for providing a seal between the two pipe ends, and a support structure for receiving the gasket, wherein the support structure is shaped to engage a pipe end to locate the gasket and acts as a stop to protect the gasket during closing of the pipe joint.

As will be appreciated, a gasket device according to the present invention provides a number of advantages over known arrangements as discussed above. Not only does is simplify location of a gasket during installation of a pipe joint, but

also prevents the gasket being crushed during closing of the joint. These are significant advantages which are not addressed by any prior art known to the inventors.

As will be appreciated, the gasket is preferably annular and has a inner diameter which corresponds substantially to the internal diameter of the pipe bore.

The support structure and gasket are preferably manufactured separately and are assembly to form a single gasket device. Alternatively, the gasket may be molded in position on a pre-formed support structure, thereby causing the two components to be bonded together.

If the support structure and gasket are manufactured separately, the gasket and support structure preferably have complementary shapes for accurate engagement. Once engaged, the two parts may be carried and used as one.

In one embodiment, the gasket defines a groove which receives a radial rib defined by the support structure. In another embodiment, the gasket defines a radial rib which engages the support structure. This radial rib may engage in a channel defined in the support structure, or may simply abut against a shoulder defined by the support structure.

In another embodiment, the gasket is an O-ring received between shoulders formed on the support structure. These shoulders may be in the form of off-set castellations around the internal surface of the support structure which abut alternate sides of the gasket.

As mentioned above, the gasket may be an elastomeric gasket, but other similar materials may be used. Rubber is one alternative.

The support structure is preferably manufactured from a hard material, preferably a plastics material. The plastic matenal IS preferably an engineering

plastics material, such as polyetherimid (ULTEM). Other engineering plastics materials, such as those highlighted above, may alternatively be used.

By providing a support structure manufactured from engineering plastics material, the support structure acts as a stop against which pipe ends can abut during closing of a pipe joint. By providing such a mechanical stop, the gasket is not destroyed or significantly distorted by overtightening.

Preferably the support structure is configured to self-center the gasket about a pipe bore. To enable this to occur, the support structure preferably comprises at least two resilient structures defining bearing surfaces for gripping a pipe end. More particularly, the support structure may include two (or three) Tshaped resilient structures spaced by approximately 1800 (or 1200).

In a particular embodiment, the support structure includes four arms spaced about its circumference, each arm including a bearing surface for gripping a pipe end. Two or more T-shaped resilient structures may be provided, each T-shaped structure defining two of the four arms.

In another embodiment, resilient structures having other shapes may be used. For example, three or more structures having a single bearing surface may be appropriate.

Typical pipe ends, or ferrules, include an annular recess for receiving an annular portion of a prior art gasket for location purposes. Although this arrangement is typically satisfactory and is defined by a British Standard, the present inventors have found that it is actually unnecessary for the gasket or support structure to incorporate a complete locating ring to achieve accurate positioning of the gasket. By providing a plurality of protrusions spaced about the gasket device for locating in the annular recess of a pipe end, adequate and accurate gasket location can be achieved. Furthermore, a gasket device with protrusions for location rather than a complete ring results in a significant saving in material and, perhaps more significantly, a significant reduction in manufacturing

time because the cooling time is significantly reduced. Hence, a gasket device according to the present invention provides a marked commercial benefit without detracting from the performance of the gasket.

Furthermore, by having a plurality of protrusions located in the annular recess of a pipe end/ferrule rather than the annular recess being filled by a complete annular portion of the gasket device, failure of the gasket can more readily become apparent due to fluid leaking out through the annular recess between the protrusions in the recess. Hence, this arrangement can act as a leak detection port, which can be extremely useful in practice. If the leak detection port is not provided and the seal at the pipe bore fails, problems can arise in hygienic food pipelines because bacteria can multiply in the resulting cavity adjacent the seal. This is clearly unsatisfactory, so the inclusion of a leak detection port which immediately alerts the user to the failure of the seal is very beneficial.

In a particular embodiment, at least two, preferably three or more, protrusions are provided for seating in an annular recess in a pipe end. If only two protrusions are included, they are preferably situated 1200 or so apart around the gasket. More preferably, however, ten or more protrusions are spaced in a ring about the gasket face for seating in an annular recess in a pipe end.

The protrusions may be bumps, cones (probably truncated) or stipples, or any other appropriately shaped protrusion for engaging in a recess, or seat, in a pipe end or ferrule. With this in mind, if the protrusions have flat tops, the protrusions can be accommodated in annular recesses to a greater or lesser degree, depending upon the force applied to the pipe joint.

Although the protrusions may extend solely from one side of a gasket device, better overall alignment between the pipe ends and the gasket device can be achieved by providing protrusions on both sides of the gasket device.

The present invention further provides a pipe joint comprising two pipe ends defined by ferrules, a clamp or screw device acting on the ferrules to close the

joint and a gasket device as claimed herein between the ferrules. By using a gasket device as herein claimed, simple installation can be achieved with improved centering of the gasket.

Specific embodiments of the present invention are now described, by way of example only, with reference to the accompanying drawings, in which :- Figure 1 is a plan view of a gasket device according to the present invention; Figure 2 is a cross-section along the line 2-2 in Figure 1; Figure 3 is a cross-sectional axial view through a pipe joint showing a ferrule and clamp ; Figure 4 is a schematic side sectional view of a pipe joint incorporating a gasket device according to the present invention; Figure 5 is a plan view of another embodiment of gasket device according to the present invention; Figures 5A, 5B and 5C are cross sections along the lines A, B and C in Figure 5; Figures 6A, 6B and 6C are cross sections corresponding to Figure 5C of other embodiments of gasket device; Figure 7 is a computer generated representation depicting cooling time for a gasket device support structure incorporating a complete locating ring; and Figure 8 is a computer generated representation depicting cooling time for a gasket device support structure incorporating locating bumps.

With reference to the drawings, a gasket device 1 according to the present invention and a pipe joint 3 according to the present invention are shown. The gasket device 1 comprises an inner sealing portion 5 and an outer support structure 6 including gripping portions 7. The inner sealing portion 5 is manufactured from a soft material, such as rubber or an elastomer, and the outer support structure 6 is manufactured in one piece from engineering plastics material, such as polyetherimid (ULTEM). The complete gasket device 1 is designed for use in the pipe joint 3 between ferrules 9 at pipe ends. The gripping

portions 7 of the gasket device 1 clip onto one (and eventually both) of the ferrules 9 such that the gripping portions 7 physically grip the outside surface of the ferrule 9. A pivoted clamping device 11, acting against tapered outside surfaces 13 of the ferrules 9 is tightened using a threaded wing nut and bolt 15 to cause a seal to be produced between the ferrules 9 and the gasket device 1.

The idea of a gasket between two pipe end ferrules tightened by a clamp is, of course, well known. Further, pipe end ferrules typically have a mating surface as shown in Figure 3, with a concentric circular groove 17 formed therein.

However, the idea of a soft material seal 5 being held in position adjacent the internal bore of a ferrule 9 by a support structure 6 is unknown in the art.

Turning now to Figures 1 and 2 specifically, the sealing portion 5 (or gasket) is essentially an annular ring of appropriate gasket material defining a bore surface 19 parallel to the axis 21 of the gasket and an adjacent raised surface 23 on either side of the bore surface 19 perpendicular to the pipe bore for abutting the mating surfaces of the ferrules 9. As can be seen in Figure 2, the sealing portion 5 has a U-shaped cross-section which engages a radial rib defined on the support structure 6 in a complementary fashion. Due to the resilience of the gasket material, the sealing portion 5 (or gasket) remains in position supported by the support structure 6 as the gasket device 1 is mounted on the pipe end ferrule 9.

The sealing portion 5 is positioned accurately and positively, thereby facilitating and simplifying the assembly of a demountable pipe joint.

Other forms of gasket cross-section can be seen in Figures 6A, 6B and 6C, which all simply require complementary formations on the support structure 6 to accommodate the annular gaskets 5. For example, Figure 6A shows an arrangement in which the gasket 5 includes a radial rib which is received within a channel formed in the support structure 6. Figure 6B shows both the gasket 5 and the support structure 6 with complementary shoulders. In this embodiment, the gasket shoulder is sandwiched between the support structure shoulder and a pipe end ferrule 9 when the gasket device 1 IS In position on a pipe end. Figure 6C shows an embodiment in which the gasket is a simple O-ring which is simply

received in a seat configuration formed on the support structure 6. For example, a series of offset castellations may be formed around the inner surface of the support structure 6 between which the O-ring is received. Alternatively, the inner surface of the support structure 6 may have a shallow concave shape for receiving the annular gasket 5. As mentioned above, many other alternatives will be immediately apparent to those skilled in the art.

The gripping portions 7 of the gasket device 1 are defined by two T-shaped resilient structures each defining a pair of arms 25 carrying a protruding bearing pip 27 for gripping each pipe ferrule 9 (as shown clearly in Figure 4). A cross section through an arm 25 can be seen in Figure 2. By providing a chamfered or lead-in surface 26 on the sides of the arms 25, it is possible to push-fit the gasket device 1 onto a pipe end ferrule 9, such that the gasket device 1 is retained on the ferrule 9 by virtue of the force supplied by the gripping portions 7 being applied through the bearing pips 27. By applying the gripping force through the pips 27, the resiliency of the arms 25 does not act to push the gasket device off the pipe ferrules 9.

By virtue of the inclusion of four arms 25, and hence four bearing surfaces 27 each exerting a force on the outside of a pipe end ferrule 9, during use, and the fact that the force increases as the distance from the center of the pipe bore increases, so a balance is achieved when all the arms 25 are distorted equally. This gives a centering action, which assists greatly in alignment of the gasket device 1 correctly relative to the axis of the pipe bore.

To assemble a pipe joint according to the present invention, it is a simple matter to apply a gasket device as shown in Figure 1 to one of the pipe end ferrules 9. The second pipe end ferrule 9 can then be brought into mating engagement with the gasket device 1 and the clamp 11 can be applied.

Tightening of the clamp will cause a reliable seal to be formed between the ferrules 9 and the gasket device 1. When undoing the pipe joint, the reverse procedure is utilised. Due to the resilience of the gripping portions 7 and the engineering plastics material of the support structure 6, it is possible to reuse the

support structure 6 in another application. The elastomeric gasket portion 5, however, may be readily replaced, if necessary.

As will be appreciated, although the specific embodiment relates to a pipe joint which uses a pivoted clamping device 11, other clamping devices, such as couplings using threaded nuts or multiple bolts in flanges, could alternatively be used.

Turning now to Figure 5 of the drawings, another gasket device 1 according to the present invention is shown. The gasket device 1 is similar to that shown in Figure 1, but where in Figure 1 a discontinuous rail 36 is included for seating in an annular recess 17 in a pipe ferrule face (cf. Figure 4), a series of bumps or truncated cones 37 are included. The profile of these bumps or truncated cones can be seen clearly in the sectional view of Figure 5B. These bumps 37 are arranged on the circumference of a circle (or ring) centered on the axis of the gasket device 1 at a radius corresponding to the radius of the annular recesses or grooves 17 in the pipe end ferrules 9. As a result, when a gasket device 1 is positioned in a pipe joint 3, the bumps 37 are seated in the annular recesses 17 to dictate and locate accurately the gasket position with respect to the pipe end ferrules 9. Thus, improved location, and hence sealing, can be achieved.

Although the gasket device 1 shown in Figure 5 includes three gripping portions of the kind previously described, in theory a gasket device could take advantage of the present invention irrespective of whether or not gripping portions are included. More particularly, a gasket device which simply has a plurality of protrusions or bumps 37 for engaging a recess or recesses in pipe end ferrules 9 could be provided, and would enable a gasket to be accurately aligned with respect to the pipe end ferrules 9. Clearly, however, the gripping portions 7 aid location of the gasket on a pipe end ferrule and assist in accurate alignment of the gasket device. The protrusions 37 also assist in this regard providing a positive stop by their location in the groove of the ferrule to the misalignment that can take place on assembly.

By manufacturing the support structure 6 of the gasket device 1 from engineering plastics material, the support structure 6 can act as a mechanical stop against over compression of the elastomeric gasket 5. Thus, destruction of the gasket 5 due to misalignment and over compression should not occur.

Turning now to Figures 7 and 8, these show computer generated representations of cooling time for a support structure 6 of a gasket device 1 incorporating a complete locating ring 39 (Figure 7) and a support structure 6 incorporating a plurality of spaced protrusions 37 (Figure 8) according to the present invention. As can be seen from the Figures, the complete locating ring 39 of Figure 7 takes a significant amount of time (7.6 seconds) to cool during moulding, whereas the bumps 37 of the gasket device support structure shown in Figure 8 are much quicker to cool. The support structure 6 of Figure 8 taking approximately 2.2 seconds to cool. Hence, a vast reduction in cooling time during manufacture can be achieved by using a gasket device according to the present invention, thereby enabling a much faster manufacturing time to be achieved.

Indeed, an improvement of 50% or more in overall manufacturing cycle time has been noted by the present inventors, thereby typically reducing the marginal cost of producing a gasket device by between 25-75%. This is clearly significant in large volume manufacturing processes.

A further benefit of a gasket device 1 according to the present invention is that there is a considerable material saving to be gained from using bumps 37 rather than a complete locating ring. In the case of a support structure 6 having a diameter of 50mm, the use of bumps 37 results in a saving of around 1% grams of a material on a support structure with a net weight after the saving of about 3% grams. This is a saving of 25% on the material consumption where material accounts for almost all the marginal costs of the component apart from the manufacturing cycle.

Overall, the result is a saving of between 33%-50%, on marginal manufacturing costs, which is not insignificant.

Another benefit arising from a support structure 6 according to the present invention is that more uniform cooling and less shrinkage occurs. This significantly reduces the risk and extent of distortion. Thus, once again, a gasket device 1 according to the present invention is a marked improvement over a prior art gasket in which a complete locating ring is formed on each face of the gasket device.

Furthermore, as will be appreciated, distortion can be a significant problem in hygienic pipe joints, and even more so when the support structure 6 of the gasket device is manufactured from engineering plastics material such as polyetherimid (ULTEM).

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

Claims

CLAIMS 1. A gasket device for a pipe joint between two pipe ends, the device comprising: a gasket for providing a seal between the two pipe ends, and a support structure for receiving the gasket, wherein the support structure is shaped to engage a pipe end to locate the gasket and acts as a compression stop to protect the gasket during closing of the pipe joint.
2. A gasket device as claimed in claim 1, wherein the gasket and the support structure have complementary shapes for accurate location.
3. A gasket device as claimed in claim 2, wherein the gasket defines a groove which receives a radial rib defined by the support structure.
4. A gasket device as claimed in claim 2, wherein the gasket defines a radial rib which engages the support structure.
5. A gasket device as claimed in claim 2, wherein the gasket is an O-ring received between shoulders formed on the support structure.
6. A gasket device as claimed in any preceding claim, wherein the gasket is an elastomeric gasket.
7. A gasket device as claimed in any preceding claim, wherein the support structure is manufactured from plastics material.
8. A gasket device as claimed in claim 7, wherein the plastics material is an engineering plastics materials, such as PEEK or ULTEM.
9. A gasket device as claimed in any preceding claim, wherein the gasket is moulded in position on the support structure.

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10. A gasket device as claimed in any preceding claim, wherein the support structure is configured to self-center the gasket about a pipe bore.
11. A gasket device as claimed in any preceding claim, wherein the support structure comprises at least two resilient structures defining bearing surfaces for gripping a pipe end.
12. A gasket device as claimed in claim 11, wherein the bearing surfaces each include a pip for contacting a pipe end.
13. A gasket device as claimed in claim 11, wherein the support structure includes at least two T-shaped resilient structures.
14. A gasket device as claimed in claim 13, wherein the T-shaped resilient structures are spaced by approximately 180 or 120 .
15. A gasket device as claimed in any preceding claim, wherein the support structure includes four or six arms spaced about its circumference, each arm including a bearing surface for gripping a pipe end.
16. A gasket device as claimed in any preceding claim, comprising: locating means comprising a plurality of protrusions spaced about the support structure for positioning the device relative to the pipe ends.
17. A gasket device as claimed in claim 16, wherein the locating means are configured to self-center the gasket device about a pipe bore.
18. A gasket device as claimed in claim 16 or 17, wherein the locating means comprise at least three protrusions for seating in an annular recess in a pipe end.
19. A gasket device as claimed in any one of claims 16 to 18, wherein the locating means include ten or more protrusions.

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20. A gasket device as claimed any one of claims 16 to 19, wherein the protrusions are bumps, truncated cones or stipples.
21. A gasket device as claimed in any one of claims 16 to 20, wherein the protrusions have flat tops.
22. A gasket device as claimed in any one of claims 16 to 21, wherein the protrusions extend from both sides of the gasket.
23. A gasket device as claimed in any one of claims 16 to 22, wherein each protrusion is substantially round in plan.
24. A gasket device as claimed in any one of claims 16 to 23, wherein each protrusion is substantially the same.
25. A gasket device substantially as hereinbefore described with reference to and as shown in the accompanying drawings.
26. A pipe joint comprising two pipe ends defined by ferrules, a clamp acting on the ferrules to close the joint and a gasket device according to any preceding claim between the ferrules.
27. A pipe joint as claimed in claim 26, wherein each ferrule includes an annular recess for receiving protrusions of the support structure of the gasket device.
28. A pipe joint as claimed in claim 26 or claim 27, wherein the support structure includes a metal stop against which the ferrules bear to prevent overtightening of the clamp.
29. A pipe joint as claimed in claim 28, wherein the ferrules contact the gasket before the stop, during clamping, thereby resulting in a sealing pressure being applied to the gasket.

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