GB2525991A

GB2525991A - Gasket assembly

Info

Publication number: GB2525991A
Application number: GB1507681.3A
Authority: GB
Inventors: Mark Williams
Original assignee: KLINGER Ltd
Current assignee: KLINGER Ltd
Priority date: 2014-05-09
Filing date: 2015-05-05
Publication date: 2015-11-11
Anticipated expiration: 2035-05-05
Also published as: GB201507681D0; GB201414034D0; GB201408263D0; GB2525991B

Abstract

A gasket assembly is provided. The gasket assembly comprises a gasket 11 and a duct 15 extending from the gasket 11. The duct 15 has a bore 16 communicating with a fluid channel opening onto a sealing face of the gasket 11 and the duct 15. The duct has an anti-rotation device 20 with a non-circular cross-section, which is optionally near an outer end of the duct 15, optionally adjacentto a tip of a connector 30. A cap 35 cooperates with the connector 30 on the duct 15 to close the opening to the central bore 16. The anti-rotation device 20 comprises a plate and can have a flat side wall, optionally a pair of parallel flat sections 21, 22 on opposite sides of the anti-rotation device 20, and can resist rotation of the duct 15 relative to the gasket 11.

Description

Title: Gasket Assembly The present invention relates to a gasket assembly, particularly a gasket assembly for sealing joints between two pipe flanges.

Background to the present invention

It is conventional to join flanged sections of pipe by compressing an annular gasket between the opposing faces of the flanges in order to prevent leaks when the bolts are tightened to make up the joint Optionally the gasket is received within cooperating annular recesses in the opposing faces of the flanges, which align to receive the gasket between the recesses.

Norwegian patent 175832 (which is useful for understanding the invention, and which is incorporated herein by reference) discloses a gasket incorporating a leak detection system, in which a tube connected to the outside the gasket allows fluid communication with a small T-shaped channel within the gasket that communicates with cavities formed between the recesses and the gasket when the gasket is sealed between the recesses. The tube extends radially from the gasket in the space between the flanges, and is accessible from the outside of the pipe when the gasket is sealed in the recess. Pressure changes within the sealed recess can be monitored from outside the flanges via the tube. In practice, the annular space between the gasket and the recess can be pressurised through the tube and the T-shaped channel. If the seal between the gasket and the recess is sufficient, the pressure will be maintained in the recess, the T-shaped channel and the tube. Conversely, in the event of a seal fault, failure to hold the pressure can provide an indication of a leak path in the seal between the gasket and the recess, indicating intervention is required in that particular joint The outer end of the tube leading to the gasket has a connector with an external thread used to connect the outer end of the tube to the source of pressurised fluid, for example, a pump, a bottle of pressurised gas, and/or a pressure gauge.

Summary of the invention

According to the invention there is provided a gasket assembly comprising a gasket, and a duct extending from the gasket, the duct having a bore, and the gasket having at least one sealing face and a fluid channel permitting fluid communication between the at least one sealing face of the gasket and the duct, wherein the duct comprises an anti-rotation device with a non-circular cross-section.

Optionally the gasket is in the form of an annukr ring having a bore, advantageously with a central axis. Optionally the annular ring has at least two sealing faces) which are optionally disposed on axially spaced portions of the annular ring.

Optionally an inner end of the duct is connected to the channel, and the duct has a connector on its outer end, optionally adapted to connect to a hose of a pressure source, such as a pump, a bottle of pressurised gas, and/or a pressure gauge. The duct optionally has an inner opening at one end into the channel in the gasket, and an outer opening outside the gasket (optionally at the other end of the duct] to the central bore of the duct, allowing fluid communication between the outer opening the bore of the duct, the inner opening, the channel in the gasket, and the sealing face of the gasket. The duct optionally is connected to the gasket, optionally to the outer surface of the gasket with respect to the bore of the gasket, and optionally extends radially outwardly from the gasket.

Optionally the anti-rotation device is located near an outer end of the duct, optionally adjacent to the connector. Optionally the connector comprises a tip.

Optionally the connector comprises an outer thread, adapted to cooperate with an internal thread of a cap, and optionally with an internal thread on a pressure delivery device, for example a pump, a bottle of pressurised gas) and/or a pressure gauge.

Optionally the duct can be generally tubular, with a generally arcuate (e.g. circukr) cross-section apart from the anti-rotation device.

Optionally the assembly comprises a cap adapted to cooperate with the connector on the duct, to close the opening to the central bore. Optionally the cap and the connector can have cooperating threads. Optionally the cap has an internal thread.

Optionally the cap has a sealing member in the form of an annular packer.

Optionally the sealing member comprises mica or a mica-containing material.

Optionally the sealing member can comprise graphite or a graphite-containing material. Optionally the sealing member has a spiral wound structure comprising an elongate length of strip mica and/or graphite material wound in a spiral in the form of an annular ring. Optionafly the spiral comprises a planar spira' coiled in a common plane. Optionally the sealing member is formed by compressing the elongate strip material when wound into the spiral. Optionally the annular ring in the sealing member has a central bore adapted to receive the externally threaded portion on the outer end of the duct. Optionally the sealing member is axially compressed in the direction of the axis of the bore of the cap, which is advantageously coaxial with the axis of the duct. Optionally the sealing member is compressed between opposing planar surfaces on the cap and the duct respectively.

Optionally the cap comprises a recess to retain the sealing member. Optionally the recess incorporates an annular planar surface, optionally in the form of a shoulder.

Optionally the recess abuts the sealing member on two surfaces. Optionally the two abutting surfaces of the recess are adjacent and are optionally disposed at right angles to one another. Optionally the sealing member abuts the recess on two surfaces, and optionally comprises at least two surfaces which do not engage the recess. Optionally the surfaces of the sealing member which do not engage the recess are adjacent surfaces, and are optionally disposed at right angles to one another. Optionally the surfaces of the sealing member which do not engage the recess engage the duct when the cap is secured in place on the duct. Optionally at least two surfaces of the sealing member engage the cap, and at least two surfaces of the sealing member engage the duct. Optionally at least one, and optionally both) of the surfaces on the sealing member which engage the duct are parallel to surfaces of the sealing member which engage the cap. Optionally the sealing member is slightly larger than the recess in at least one dimension, and is compressed into the recess when the cap is connected to the duct.

Optionally the cap connects to the duct by a screw thread mechanism, which transmits torque applied to the cap into axial compression to compress the sealing member in the recess.

Optionally the anti-rotation device comprises a plate. Optionally the anti-rotation device is radially spaced from the end of the duct, with the connector between the end of the duct and the plate. Optionally the pkte is adjacent to the connector, and in certain examples, the plate forms part of the connector.

Optionally the connector at the end of the duct is located between the flanges of the pipe joint in which the gasket is retained. Optionally the end of the duct does not protrude beyond the radial extent of the flanges of the pipe joint Optionally when the cap is attached to the connector on the end of the duct, the cap is disposed between the flanges of the pipe joint. Optionally the cap does not protrude beyond the radial extent of the flanges of the pipe joint.

Optionally the anti-rotation device has at least one side wall extending in an axial direction parallel to the axis of the bore of the duct. Optionally the at least one side wall can incorporate at least one flat section. Optionally the anti-rotation device has a noncircifiar cross-section in a plane perpendicular to the axis of the duct.

Optionally the anti-rotation device can comprise more than one flat section, and optionally can comprise a pair of parallel flat sections on opposite sides of the anti-rotation device. Optionally the anti-rotation device can be at least partially symmetrical, and in particular can have at least a partially symmetrical cross- section in the plane perpendicular to the axis of the duct. Optionally the cross-section of the anti-rotation device can be at least partially rectilinear. Optionally the cross-section of the anti-rotation device can be at least partially square or rectangular. Optionally the anti-rotation device has a pair of short sides and a pair of long sides. Optionally the long sides are longer than the short sides. Optionally the anti-rotation device resists rotation of the duct relative to the gasket. Optionally the anti-rotation device has at least one configuration in which it resists rotation of the duct relative to the gasket. Optionally the anti-rotation device can have more than one configuration in which it resists rotation of the duct relative to the gasket.

Optionally the anti-rotation device is disposed between the opposing faces of the flanges in the pipe joint. Optionally the anti-rotation device does not extend beyond the radial extent of the flanges of the pipe joint.

Optionally the flat sections of the anti-rotation device abut against opposing faces of the flanges in the pipe joint when the pipe joint is made up with the gasket in place.

Optionally the opposing faces of the flanges in the pipe joint compress the flat sections of the anti-rotation device, but in certain examples, the axial distance between the flat sections of the anti-rotation device (with respect to the axis of the pipe joint] is less than the axial distance between the opposing faces of the flanges in the pipe joint when the pipe joint is made up with the gasket in place. Accordingly, it is possible in certain examples for the anti-rotation device to be axially spaced by a small distance from the opposing faces of the flanges in the pipe joint when the pipe joint is made up.

Optionally the flat sections of the anti-rotation device extend radially outwards (with respect to the axis of the duct] beyond other components of the anti-rotation device and of the duct. Accordingly, flat sections of the anti-rotation device are generally the only portions of the anti-rotation device which are engaged by the opposing faces of the flanges when the pipe joint is made up with the gasket in place.

Application of torque to the connector during connection of the hose in some embodiments induces partial rotation of the duct relative to the gasket, damped within the pipe joint) but optionally the extent of rotation of the duct relative to the gasket is limited within the intra-flange space by the anti-rotation device provided on the duct) which is optionally rotated into a position in which it limits or prevents further rotation of the duct, while permitting increased torque to be applied to the duct without rotation of the duct relative to the gasket, in order to make up a connection on the end of the duct, for example between the duct and a hose connecting the duct to the source of pressurised fluid. Optionally the extent of rotation of the duct permitted by the anti-rotation device is very small, for example less than 5°, for example 1° or even less, and in some examples, there is no rotation permitted at all. By limiting or preventing the permitted rotation of the duct relative to the gasket, during application of torque to the duct while making up the connection, the anti-rotation device reduces the risks of creating leak paths between the duct and the gasket through weld failures or other joint faults arising as a result of application of torque beyond the stress limits of the duct The various aspects of the present invention can be practiced alone or in combination with one or more of the other aspects, as will be appreciated by those skilled in the relevant arts. The various aspects of the invention can optionally be provided in combination with one or more of the optional features of the other aspects of the invention. Also, optional features described in relation to one aspect can optionally be combined alone or together with other features in different aspects of the invention. Any subject matter described in this specification can be combined with any other subject matter in the specification to form a novel combination.

Various aspects of the invention will now be described in detail with reference to the accompanying figures. Still other aspects) features, and advantages of the present invention are readily apparent from the entire description thereoL including the figures, which illustrates a number of exemplary aspects and imp'ementations. Any subject matter described in the specification can be combined with any other subject matter in the specification to form a novel combination. The invention is also capable of other and different examples and aspects, and its several details can be modified in various respects) all without departing from the spirit and scope of the present invention. Accordingly, the drawings and descriptions are to be regarded as illustrative in nature, and not as restrictive. Furthermore, the terminology and phraseology used herein is solely used for descriptive purposes and should not be construed as limiting in scope.

Language such as "including" "comprising" "having" "containing" or "involving," and variations thereof, is intended to be broad and encompass the subject matter listed thereafter, equivalents, and additional subject matter not recited, and is not intended to exclude other additives, components, integers or steps. Likewise, the term "comprising" is considered synonymous with the terms "including' or "containing" for applicable legal purposes.

Any discussion of documents, acts, materials, devices, articles and the like is included in the specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any or all of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present invention.

In this disclosure, whenever a composition, an element or a group of elements is preceded with the transitional phrase "comprising", it is understood that we also contemplate the same composition, element or group of elements with transitional phrases "consisting essentially of', "consisting", "selected from the group of consisting of', "including', or "is" preceding the recitation of the composition, element or group of elements and vice versa. In this disclosure, the words "optionally" or "optionally" are to be understood as being intended to indicate optional or non-essential features of the invention which are present in certain examples but which can be omitted in others without departing from the scope of the invention.

All numerical values in this disclosure are understood as being modified by "about".

All singular forms of elements, or any other components described herein are understood to include plural forms thereof and vice versa. References to directional and positional descriptions such as upper and lower and directions e.g. "up", "down" etc. are to be interpreted by a skilled reader in the context of the examples described and are not to be interpreted as limiting the invention to the literal interpretation of the term, but instead should be as understood by the skilled addressee.

Brief description of the drawings

In the accompanying drawings: figure 1 is an end view of a flange on which is disposed a gasket assembly visible in plan view; figure 2 is a close up of a duct of the gasket assembly in figure 1; figure 3 is a section view through a pipe joint comprising the flange and gasket assembly of figure 1; figure 4 is a close up view of the gasket assembly of figure 3; figure 5 is a side view of the pipe joint in figure 3 showing an end view of the duct in the gasket assembly, with the cap removed; figure 6 is a close up of the end view of the duct in figure 5; figure 7 is a sectional side view through the gasket assembly in figure 3; figure 8 is an end view of the gasket assembly with a cap in place and visible in end view; figure 9 is an end view similar to figure 8, but with the cap removed; figure 10 is at sectional side view through the cap; figure 11 is an end view of the cap; and Figure 12 shows a sectional view of the pipe joint in Fig 3, with the cap removed the duct connected to a hose leading to a pressure source; Figure 13 is a side view of an alternative design of gasket assembly; Figures 14-16 shows close up perspective views of the Figure 13 assembly from different ang'es; and Figure 17 is a close up view from the side of the Figure 13 assembly with the cap removed.

Detailed description of one or more examples of the invention Referring now to the drawings, a gasket assembly in one example comprises a gasket in the form of an annular ring 11 which optionally has a circular and symmetrical cross-section) and which is received within an opposed pair of annular recesses R in opposing faces of flanges F in a pipe joint. The pipe joint has an axis X-X, which is optionally coaxial with the central axis of a bore through the annular ring 11 of the gasket, as best shown in figure 3. The plane of the annular ring 11 is perpendicular to the axis of the bore through the ring, as best shown in figure 3. The pipe joint is held together by bolts or similar fixings extending through boftholes in the flanges, which are tightened to make up the joint. The flanges F are optionafly spaced apart along the axis of the pipe joint by the annular ring 11 of the gasket when the annular ring 11 is received within the recesses R creating an axial spacing in the made up joint. The annular ring 11 of the gasket assembly 10 optionally has an octagonal cross section as best shown in figures 3 and 4, and when received within the recesses R, creates a small cavity between the annular ring of the gasket and the walls of the recess R. The dimensions of each recess Rand the annular ring 11 are usually controlled very precisely, so the precise axial spacing between the opposing end faces of the flanges F is usually known to a relatively high degree of accuracy in each case. The angled sidewalls of the recess R provide inner and outer radially spaced seals against corresponding angled and radially spaced faces on the octagonal cross-section of the annular ring 11, to provide a seal to contain fluids within the bore of the pipe.

Spacing the flanges axially apart from one another as described above enables passage of a duct 15 in the form of a cylindrical tube [in this example) between the opposing faces of the flanges F to allow fluid communication through the duct 15 with the annular ring 11. The duct 15 has an axis which is optionally perpendicular to the axis X-X, and has a bore 16 (optionally a central bore that is coaxial with the axis of the duct] which communicates with a T-or L-shaped channel in the annular ring 11 communicating with at least one of the cavities formed between the recess R and the annular ring 11 when the gasket assembly 10 is damped in place between the flanges F. The radially inner end of the duct 15 is connected to the radially outermost surface of the annular ring 11, optionally by means of a screw thread, or by welding, brazing soldering or by some other connection mechanism. The radially outer end of the duct 15 optionally has a connector 30 with an open end 31, an opening to the bore of the duct 15.

Optionally the gasket assembly 10 comprises a cap 35 adapted to cooperate with the connector 30 on the duct 15, to close the radially outermost opening to the central bore 16 on the end of the duct 15. Optionally the cap 35 and the connector 30 can have cooperating threads. Optionally the cap 35 has a blind ended cylindrical bore 37 with an internal thread and one open end. Optionally the connector 30 has a generally cylindrical outer surface with an external thread 32. The internal thread on the blind ended bore 37 on the cap 35 optionally cooperates with the externa' thread 32 on the connector 30 to seal an open end 31 of the bore 16 in the duct 15.

The external threads 32 on the connector 30 are optionally also adapted to cooperate with an internal thread on a pressure delivery device, for example a hose leading to a pump, a bottle of pressurised gas, and/or a pressure gauge.

Optionally the connector 30 has an inwardly tapering chamfer 33 at the radially outer end of the thread 32, between the end of the thread 32 and a tip 34. The chamfer 33 tapers inwardly towards the open end 31 and guides the inner bore of the cap 35 onto the connector 30 so that the threads between the cap 35 and the connector 30 approach one another in alignment, and so that crossing of the threads is reduced when making up the connection. The tip 34 steps inwardly in diameter above the chamfer 33, and has a shoulder 34s extending radially with respect to the axis of the bore 16, facing the open end 31. Above the shoulder 34s, the tip 34 has a narrow cylindrical stem leading to the open end 31 of the bore 16 of the duct 15.

The cap 35 optionally has a sealing member 40 in the form of an annular packer.

The sealing member could instead be located on the connector 30, for example on the tip 34. Optionally the sealing member 40 comprises a mica material. In other examples the sealing member can incorporate a graphite material, instead of or in addition to the mica material. In this example, the sealing member 40 comprises a spiral wound structure comprising an elongate length of thin strip mica (or graphite) material wound in a spiral into the form of an annular ring. The sealing member 40 is formed by compressing the elongate strip material when it is wound into the spiral, causing or inducing the strips to adhere together to form the annular i-i-ring structure. The annular ring of the sealing member 40 has a central bore adapted to receive the narrow stem on the end of the tip 34 of the connector 30.

In the present example, the cap 35 comprises a recess 38 to retain the sealing member 40. The recess 38 incorporates an annular planar surface, optionally in the form of a shoulder 38s extending radially with respect to the axis of the cap 35, which is coaxial with the axis of the bore 16 of the duct 15. The shoulder 38s faces toward the open end of the cap 35. The recess 38 in the cap 35 abuts the sealing member 40 on two abutting surfaces formed by the annular planar shoulder 38s and the arcuate inner surface of the bore 37 of the cap. The two surfaces are adjacent, abutting and disposed at right angles to one another, so that the sealing member 40 abuts the recess 38 on two surfaces, but the sealing member 40 comprises at least two other surfaces which do not engage the cap 35, and which instead engage the connector 30 when the two are made up. The surfaces of the sealing member 40 which do not engage the cap are also adjacent, abutting and disposed at right angles to one another. These surfaces comprise an annular planar end surface of the sealing member 40, which faces the open end of the cap 35 and which abuts against the arcuate planar surface of the shoulder 34s on the connector 30, and an arcuate inner surface of the generally cylindrical sealing member 40, which abuts against the outer surface of the stem on the end of the tip 34 when the cap 35 is screwed onto the connector 30. The cap 35 connects to the duct 15 by the cooperation of the screw threads on the cap 35 and the connector 30, which transform torque applied to the cap 35 into axial compression to compress the sealing member axially within the recess 38.

The sealing member 40 is seated on the radially extending shoulder 38s. The radially extending shoulder 38s faces the radially extending shoulder 34s, and is parallel to it. The sealing member 40 is axially compressed in the direction of the axis of the bore 16 of the duct 15, coaxial with the long axis of the cap 35, between the opposing planar surfaces formed by the shoulders 34s and 38s when the cap 35 is tightened onto the connector 30 of the duct 15.

At the closed end of the cap 35, the outer surface optionally has a hexagonally-shaped recess which receives a torque tool such as an Allen key or the like, so that torque can be applied to the cap to tighten it onto the connector 30. Optionally, the torque tool can incorporate a torque limiting and/or torque indicating mechanism serving to indicate and/or limit the torque applied to the cap 35 when making up the connection. Optionally the torque tool can retain the cap on the end of the torque tool (for example with a sprung ball bearing or the like) to facilitate handling of the cap on the end of the torque tool and deploymentof the cap into the narrow axial space between the flanges F. Thus the torque tool can be used to deploy the cap into position, and can be used to apply very high torque to the cap to tighten it in place on the connector 30.

Thus the surfaces of the sealing member 40 which do not engage the cap 35 engage the connector 30 on the duct 15 when the cap 35 is secured in place on the connector 30. In this example, the sealing member 40is slightly larger than the recess 38 in at least one dimension (optionally the radial dimension) and is compressed into the recess 38 when the cap 35 is connected to the connector 30 on the duct 15.

The sealing member 40 is advantageously able to withstand significant compressive loads with minimal "creep" of the mica material. The mica strips that are wound in the spiral optionally have an adhesive quality, which binds the strips together, and reduces the extent to which the strips the associate with one another when placed under compressive loads when the cap 35 is screwed into place on the connector 30.

Optionally the strips are wound into the spiral form and then compressed by up to 25-30% before being deployed, which also tends to bind the mica strips together and increase coherence in the sealing member 40.

An additional advantage provided by the present example is that the mica sealing material in the sealing member 40 exhibits significant resistance to fire. This is a significant improvement over polymeric seal rings used in earlier gasket assemblies, as if the fluid communication pathway through the duct, T-shaped channel, gasket and recess is compromised in a leaking joint, then the mica sealing member 40 provides a more reliable fire resistant barrier as well as being able to contain the pipeline fluids.

The duct 15 comprises an anti-rotation device with a non-circular cross-section. In this example, the anti-rotation device is located near an outer end of the duct 15, forming part of the connector 30. The anti-rotation device in this example comprises a plate 20 which has a rectangular cross-section as best shown in figure 5. The plate 20 is radially spaced from the end of the duct, with the connector 30 between the open end 31 of the duct 15 and the plate 20. In this example, the duct 15, the connector 30 and the plate 20 are located between the flanges F of the pipe joint in which the gasket assembly lOis retained. The end of the duct 15 and the end of the cap 35 (and thus the plate 20) are each contained within the radial extent of the flanges F. The plate 20 optionally has two pairs of sidewalls each pair extending parallel to the axis of the bore 16 of the duct 15. In this example, the plate 20 has a first pair of sidewalls 21 that are arranged perpendicular to the plane of the annular ring 10 of the gasket The plate 20 has a second pair of sidewalls 22 arranged parallel to (but optionally spaced from) the plane of the annular ring 10. The sidewalls 21 are optionally longer than the sidewalls 22, so that the plate has a generally rectangular configuration, with the pair of opposing and parallel long sides 21, and the pair of opposing and parallel short sides 22. Note that the rectangular configuration is only one option for the anti-rotation device, and could be modified in other examples of the invention.

The sidewalls 21, 22 extend in an axial direction parallel to the axis of the bore of the duct, and each sidewall 21, 22 incorporates at least one flat section to form a noncircular cross-section in the plane perpendicular to the axis of the duct, as best seen in figure 6, thereby providing parallel flat sections on opposite sides of the plate 20. The plate 20 has a symmetrical rectangular cross-section in the plane perpendicular to the axis of the bore 16 of the duct 15. The plate 20 resists rotation of the duct 15 relative to the annular ring 11 because the flat sections of the sidewalls 22 extend radially outwards (with respect to the axis of the duct) beyond other components of the connector 30 so they are engaged first by the opposing faces of the flanges F when the pipe joint is made up with the gasket assembly in place. Thus the flat sections of the sidewalls 22 of the plate 20 abut against opposing faces of the flanges F in the pipe joint when the pipe joint is made up with the gasket assembly 10 in place as best seen in figure 6. In this example, the opposing inner faces of the flanges F engage and compress the flat sections of the sidewalls 22 of the plate 20 because the axial distance [with respect to the axis of the pipe joint) between the sidewalls 22 (i.e. the length of the sidewalls 21) is very slightly less than the distance between the opposing faces of the flanges F when the joint is made up with the gasket assembly 10 in place.

When torque is applied to the connector 30 during connection of the hose 50, or during connection of the cap 35, this normally transfers rotation moments to the duct to rotate relative to the annular ring 11 clamped within the pipe joint, but as the connector 30 begins to experience the rotational force, the sidewalls 22 abut against the faces of the flanges F and inhibit rotation of the duct 15 relative to the gasket 30. In this example, the intra-flange spacing is very slightly more than the length of the sidewalls 21, because it is advantageous that the very large compressive forces that are experienced by the annular ring 11 when clamped into the recesses Rare then not applied directly to the plate 20, which only needs to resist or limit rotation, and does not need to withstand leaks etc. in the same way as the annular ring 11. Hence, some limited rotation of the duct 15 within the intra-flange space is acceptable, but this is limited by the pkte 20 provided on the duct 15, which is rotated into position in which it prevents further rotation of the duct 15, while permitting increased torque to be applied to the connector without transfer to the duct 15. Therefore, the cap 35 can be screwed tightly onto the threads of the duct 15 under very high torque applied by the Allen key or other torque toot in order to make up a fluid tight connection on the end of the duct, or to close the bore 16. The extent of rotation of the duct permitted by the anti-rotation device is very small, for example less than 5°, and in this example, less than 10 in order to avoid stress to the welds or screw connections between the duct 15 and the ring 11. In some cases the plate 20 could resist rotation entirely. By limiting the permitted rotation of the duct 15 relative to the ring 11, during application of torque to the duct 15 while making up the connection, the plate 20 reduces the occurrence of leak paths between the duct 15 and the annular ring 11 as a result of application of torque beyond the stress limits of the duct 15 or its connection.

Other forms of plate can be used for the anti-rotation device, for example hexagonal, square etc., and while parallel pairs of opposing flats are useful and are illustrated in the present example, it is sufficient to have a single flat, or even an oval or some other noncircular shape for the anti-rotation device. The anti-rotation device can optionally have a mixture of flat and arcuate sides in certain examples.

Referring now to Figures 13-17, a second gasket assembly 110 is similar to the first gasket assembly 10 and similar features are labelled with the same reference number, increased by 100. The assembly 110 differs from the assembly 10 in respect of the annular ring 111 which as best shown in Figure 13 has the form of a generally flat plate with a generally round circumference having a flat section ilif.

The ring 111 has radially spaced apart annular raised sealing surfaces 112, 113, separated by a groove 114. The ring 111 is received within an opposed pair of annular recesses in opposing faces of flanges in a pipe joint as previously described (not shown), but the recess for the ring 111 has a complimentary shape. The sealing surfaces 112, 113 cooperate with sealing areas on the flanges to seal with pipe joint.

The pipe joint axis is coaxial with the central axis of a bore 1 llb through the annular ring 111, and the plane of the annular ring 111 is perpendicular to the axis of the bore lllb.

The assembly 110 has a duct 115 in the form of a cylindrical tube disposed between the opposing faces of the flanges to allow fluid communication through the bore of the duct 115 with the annular ring 111 as previously described in the previous example. The duct 115 has an axis which is perpendicular to the axis of the pipe connection, and the bore of the duct 115 which communicates with a T-or L-shaped channel in the annular ring 111 communicating via an opening 114o with the groove 114 formed between sealing surfaces 112, 113 of the annular ring 111 when the gasket assembly 110 is clamped in place between the flanges. The radially inner end of the duct 115 is connected to the flat section lllf of the annular ring 111, optionally by means of a screw thread, or by welding, brazing soldering, or by some other connection mechanism. The radially outer end of the duct 115 optionally has a connector 130 with an open end 131, an openingto the bore of the duct 115.

Optionally the gasket assembly 110 comprises a cap 135 adapted to cooperate with the connector 130 on the duct 115, to close the radially outermost opening 131 to the central bore on the end of the duct 115. The cap 135 is optionally the same as the cap 35 described in the previous example and cooperates with threads 132.

The connector 130 is optionally the same as the connector 30 described in the previous example. The duct 115 comprises an anti-rotation device with a non-circular cross-section, comprising a plate 120. The plate 120 is optionally the same as the plate 20 described in the previous example. For brevity, the common features between the examples will not be repeated, but the reader is referred to the earlier

description for details of these features.

When torque is applied to the connector 130 for example during connection of the cap 135, this normally transfers rotation moments to the duct to rotate relative to the annular ring 111, but as the connector 130 begins to experience the rotational force) the sidewalls of the plate 120 abut against the inner faces of the flanges as previously described and inhibit rotation of the duct 115 relative to the ring 111. As before, the intra-flange spacing is optionally very slightly more than the dimensions of the plate 120 because it is advantageous that the very large axial compressive forces that are experienced by the annular ring 111 are then not applied directly to the plate 120, which only needs to resist or limit rotation, and does not need to withstand leaks etc. in the same way as the annular ring 111. Hence, some limited rotation of the duct 115 within the intra-flange space is acceptable, but this is limited by the plate 120 provided on the duct 115, which is rotated into position in which it prevents further rotation of the duct 115, while permitting increased torque to be applied to the connector without transfer to the duct 115. Therefore, the cap 135 can be screwed tightly onto the threads of the duct 115 under very high torque applied by the Allen key or other torque to in order to make up a fluid tight connection on the end of the duct, or to close the bore of the duct 115. The extent of rotation of the duct 115 permitted by the anti-rotation device is very small, for example less than 5°, and in this example, less than 1° in order to avoid stress to the welds or screw connections between the duct 115 and the ring 111. By limiting the permitted rotation of the duct 115 relative to the ring 111, during application of torque to the duct 115 while making up the connection) the plate 120 reduces the risk of creation of new leak paths between the duct 115 and the annular ring 111 as a result of application of torque beyond the stress limits of the duct 115 or its connection to the ring 111.

Claims

Claims 1 A gasket assembly comprising a gasket and a duct extending from the gasket, the duct having a bore, and the gasket having at least one sealing face and a fluid channel permitting fluid communication between the at least one sealing face of the gasket and the duct, wherein the duct comprises an anti-rotation device with a non-circubr cross-section.
2 A gasket assembly as claimed in claim 1, wherein the gasket comprises an annular ring having a bore with a central axis, and at least two sealing faces disposed on axially spaced portions of the annular ring.
3 A gasket assembly as claimed in claim 1 or claim 2, wherein an inner end of the duct is connected to the channel.
4 A gasket assembly as claimed in any one of claims 1 to 3, wherein the duct has an inner end connected to the gasket, and a free outer end, a connector on its outer end, an inner opening at its inner end into the channel in the gasket, and an outer opening outside the gasket to a bore of the duct, allowing fluid communication between the outer opening, the bore of the duct, the inner opening, the channel in the gasket, and the sealing face of the gasket.
A gasket assembly as claimed in any one of claims 1 to 4, wherein the duct is connected to the outer surface of the gasket with respect to the bore of the gasket, and extends radially outwardly from the gasket.
6 A gasket assembly as claimed in any one of claims ito 5, wherein duct has a connector on its outer end, and wherein the anti-rotation device is located between the connector and the gasket.
7 A gasket assembly as claimed in any one of claims ito 6, wherein the assembly comprises a cap adapted to cooperate with the duct, to close an outer opening of the duct.
8 A gasket assembly as claimed in any one of claims 1 to 7, including a sealing member in the form of an annular packer comprising a mica material.
9 A gasket assembly as claimed in claimS, wherein the sealing member has a spiral wound structure comprising an elongate length of strip mica material wound in a spiral in the form of an annular ring.
A gasket assembly as claimed in claims or claim 9, wherein the sealing member is formed by compressing the elongate strip material when wound in the spiral form.
11 A gasket assembly as claimed in any one of claims 8-10, when dependent on claim 7, wherein the cap comprises a recess to retain the sealing member, wherein the recess incorporates an annular planar surface, and abuts the sealing member on two surfaces.
12 A gasket assembly as claimed in claim 11, the two abutting surfaces of the recess are adjacent and disposed at right angles to one another.
13 A gasket assembly as claimed in any one of claims 11-12, wherein the sealing member comprises at least two adjacent perpendicular surfaces which do not engage the recess, but which engage the duct when the cap is secured in place on the duct.
14 A gasket assembly as claimed in any one of claims 1-13, wherein the anti-rotation device comprises a flat plate.
A gasket assembly as claimed in claim 14, wherein the anti-rotation device is radially spaced from the end of the duct, with the connector between the end of the duct and the plate.
16 A gasket assembly as claimed in claim 14 or claim 15, wherein the plate forms part of the connector.
17 A gasket assembly as claimed in any one of claims 1-16, wherein the duct is located in an axial space between the flanges of a pipe joint in which the gasket is retained) and wherein the anti-rotation device is located within the radial extent of the flanges of the pipe joint 18 A gasket assembly as claimed in any one of claims 1-17, when dependent on claim 7, wherein when the cap is attached to the connector on the end of the duct, the cap is disposed between the flanges of the pipe joint, and wherein the cap does not protrude beyond the radial extent of the flanges of the pipe joint.19 A gasket assembly as claimed in any one of claims 1-18, wherein the anti-rotation device has at least one wall extending in an axial direction parallel to the axis of the bore of the duct, and incorporating at least one flat section.A gasket assembly as claimed in any one of claims 1-19, wherein the anti-rotation device has a noncircular cross-section in a plane perpendicular to the axis of the duct.21 A gasket assembly as claimed in any one of claims 1-20, wherein the anti-rotation device comprises more than one flat section on a sidewall thereof 22 A gasket assembly as claimed in any one of claims 1-21 wherein the anti-rotation device comprises a pair of parallel flat sections on opposite sides of the anti-rotation device.23 A gasket assembly as claimed in any one of claims 1-22, wherein the anti-rotation device is at least partially symmetrical.24 A gasket assembly as claimed in any one of claims 1-23, wherein the anti-rotation device has at least a partially symmetrical cross-section in the plane perpendicular to the axis of the duct A gasket assembly as claimed in any one of claims 1-24 wherein the cross-section of the anti-rotation device is at least partially rectilinear.26 A gasket assembly as claimed in any one of claims 1-25 wherein the cross-section of the anti-rotation device is at least partially square or rectangular.27 A gasket assembly as claimed in any one of claims 1-26, wherein the anti-rotation device has a pair of short sides and a pair of long sides, wherein the long sides are longer than the short sides.28 A gasket assembly as claimed in any one of claims 1-27 wherein the anti-rotation device resists rotation of the duct relative to the gasket.29 A gasket assembly as claimed in any one of claims 1-28 wherein the anti-rotation device has at least two configurations in which it resists rotation of the duct relative to the gasket.30 A gasket assembly as claimed in any one of claims 1-29, wherein the anti-rotation device is disposed between the opposing faces of the flanges in the assembled pipe joint.31 A gasket assembly as claimed in any one of claims 1-30 wherein the anti-rotation device does not extend beyond the radial extent of the flanges in the assembled pipe joint.32 A gasket assembly as claimed in any one of claims 1-3 1, wherein at least one flat section of the anti-rotation device engages a face of at least one of the flanges in the pipe joint when the pipe joint is made up with the gasket in place.33 A gasket assembly as claimed in any one of claims 1-32 wherein the opposing faces of the flanges in the pipe joint compress the flat sections of the anti-rotation device.34 A gasket assembly as claimed in any one of claims 1-33 wherein the anti-rotation device is axially spaced from the opposing faces of the flanges in the pipe joint when the pipe joint is made up.A gasket assembly as claimed in any one of claims 1-34, wherein the flat sections of the anti-rotation device extend radially outwards (with respect to the axis of the duct] beyond other components of the anti-rotation device and of the duct.36 A gasket assembly as claimed in any one of claims 1-3 5, wherein flat sections of the anti-rotation device are the only portions of the anti-rotation device which are engaged by at least one flange when the pipe joint is made up with the gasket in place.37 A gasket assembly as claimed in any one of claims 1-36, wherein flat sections of the anti-rotation device are engaged by each flange when the pipe joint is made up with the gasket in place) and wherein the anti-rotation device prevents rotation of the duct between the flanges with the pipe joint is made up.38 A gasket assembly as claimed in any one of claims 1-36 wherein application of torque to the connector induces partial rotation of the duct between the flanges relative to the gasket clamped within the pipe joint and wherein the extent of rotation of the duct relative to the gasket is limited within the intra-flange space by the anti-rotation device provided on the duct, and wherein the partial rotation of the duct within the intra-flange space in the joint rotates the anti-rotation device into a position in which it limits or prevents further rotation of the duct between the flanges, while permitting increased torque to be applied to the duct and preventing rotation of the duct relative to the gasket when making up a connection on the end of the duct.39 A gasket assembly as claimed in any one of claims 1-38, when dependent on claim 7, wherein the cap has a non-circular recess which receives a torque tool to apply torque to the cap.A gasket assembly as claimed in claim 39, wherein the torque tool incorporates a torque limiting mechanism.41 A gasket assembly as claimed in claim 39 or 40, wherein the torque tool incorporates a torque indicating mechanism.42 A gasket assembly as claimed in any one of claims 39-41, wherein the torque tool incorporates a cap retention device to retain the cap on the torque tool.43 A method of making up a connection to a duct on a gasket assembly in a pipe joint having at least one flange, the gasket assembly comprising a gasket, and wherein the duct extends from the gasket, the duct having a bore, and the gasket having at least one sealing face and a fluid channel permitting fluid communication between the at least one sealing face of the gasket and the duct, and wherein the duct comprises an anti-rotation device with a non-circular cross-section, wherein the method comprises applying torque to the duct to make up a connection) and resisting rotational movement of the duct relative to the gasket by interaction between the anti-rotation device and at least one the inner face of the flange of the pipe joint.