The present application relates to gaskets and to a method of effecting a seal between opposed surfaces

Gaskets are deployed to seal opposed surfaces, for example to seal together neighbouring conduits. The gaskets are frequently subjected to high compression forces or stresses, resulting from the high temperatures or pressures of the material passing through the conduit. These stresses or compression forces can result in the distortion of the gasket. For example, flanges of the gaskets may pivot disadvantageously, potentially affecting the quality of the seal.

GB 2010 417 discloses a rigid sealing unit.

WO 9429620 discloses a solid gasket with concentric arced ridges.

CN 203477686 discloses a slurry pump sealing device

DE 9005064.9 and DE 19706889 disclosure a ductile and creep resistant metal support ring including inner and outer radial shoulders.

DE 4139453, US 5580068 and DE 3904933 also relate to seals.

It is an aim of the invention to overcome the above-mentioned disadvantages, and any other disadvantages that would be apparent to the skilled reader from the description herein.

According to the present invention there is provided an apparatus and method as set forth in the appended claims. Other features of the invention will be apparent from the dependent claims, and the description which follows.

According to one aspect there is provided a gasket for forming a seal between opposed surfaces, the gasket including a pair of opposed sealing flanges extending from a junction region with the junction region and the flanges being integrally formed, characterised in that there is at least a partial gap between the flanges and in that an outwardly facing surface of each flange includes a plurality of peripherally spaced peaks with grooves being defined between adjacent peaks and in that a line connecting the peaks on each side of the gasket is straight and in that the height of the peaks in a central region on each outwardly facing surface of the gasket is less than the height of the peaks at an outer region.

The line connecting the peaks included on the outwardly facing surface of one of the flanges may be termed a first line. The line connecting the peaks included on the outwardly facing surface of the other of the flanges may be termed a second line. By peripherally spaced peaks, it is meant that the peaks are disposed on the periphery of the outwardly facing surface of each flange, spaced apart by the grooves, typically, in the direction which the flanges extend from and to the junction region. The direction in which the flanges extend from and to the junction region may be termed a radial direction. In the case of an "o"- ring gasket the flanges extend in a radially inward direction from the junction region and therefore, the peaks are spaced apart by the grooves in a radial direction.

The junction region may include at least one peak extending from each side with the line connecting that at least one peak with the other peaks on each side being straight.

The lines on each outwardly facing surface may be parallel or may diverge from each other.

A line connecting bottoms of the grooves or troughs on each side may be curved and may be arcuate.

The peaks on each side may be equidistant from each other.

The depth of the gasket between opposed peaks on each side relative to the radial extent of the gasket may be less than 4:1 or less than 3:1 or less than 2:1 or less than 1 :1 .

The distance between peaks on opposite sides of the gasket may be less than 6 or less than 5 or less than 4 or less than 3.5 mm.

At least one of the grooves may include a curved profile extending from a peak.

At least one of the grooves may include a curved profile forming the lower part of the groove.

The curved profile may comprise a convex profile.

There may be three or more peripherally spaced peaks on each side of the gasket.

The at least partial gap between the flanges may have been machined.

The gasket may include soft sealant material extending at least partially into the grooves.

It will be apparent to the skilled reader that references to line(s) herein are references to notional lines..

According to another aspect a method of effecting a seal to prevent a high pressure source passing through two surfaces to a lower pressure with a gasket according to the first aspect comprises:

clamping the opposed peaks of the gasket between the two surfaces, and causing the high pressure source to be exerted in the at least partial gap between the flanges thereby acting on the flanges to enhance the seal.

The method may comprise locating the gasket in an O ring groove formed in at least one of the surfaces.

The method may comprise causing the surfaces to abut each other when the gasket effects the seal.

The method may comprise causing the surfaces to pivot about a radially located central region of the gasket when the surfaces to be sealed are not parallel to each other.

The gasket provides a peripheral seal between opposed surfaces. These may be opposed surfaces on a valve bonnet. The gasket may effect a seal where the radial space to effect a seal is limited. The gasket may effect a seal where flanges to be sealed are load compromised where the flanges may be relatively flimsy or where there is reduced bolting between opposed flanges. The gasket may effect a seal between opposed surfaces where thermal and or pressure cycling is effected and where the gasket maintains a seal through the cycles. The gasket may effect a seal where the finish of a sealing surface has been compromised.

The present idea can be carried into practice in various ways but one embodiment will now be described by way of example and with reference to the accompanying drawings in which :

Figure 1 is a cross section through a gasket 10;

Figure 2 is a detail of one surface of the gasket 10;

Figure 3 is a view of the gasket 10 located between two surfaces to be sealed;

Figure 4 is a cross section through an alternative embodiment of a gasket 1 10;

Figure 5 is a view of the gasket 1 10 between two surfaces to be sealed.

Figure 6 is a schematic view of two conduits connected together with the seal being effected by the gasket 10;

Figure 7 is a schematic exaggerated view of one side of two conduits that are connected together by flanges that are sealed by a gasket not in accordance with the present idea with the flanges not being parallel to each other; and

Figure 8 is a view similar to Figure 7 with a gasket according to the present idea with the flanges not being parallel to each other; and

Figure 9 is a view similar to Figure 7 with the flanges being dished. In the drawings, corresponding reference characters indicate corresponding components. The skilled person will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various example embodiments. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various example embodiments.

The gasket 10 includes a cavity 12 defined at least partially between opposed sealing flanges 14 and 16. The inwardly facing surfaces 18 and 20 of each flange extend parallel to each other over at least part of their coexistent.

The cavity 12 is closed at the end by a junction 22 that connects the flanges 14 and 16. The surface 24 of the junction that closes the end of the junction cavity is curved and may include an arcuate section and may include a semicircle. Accordingly, the gasket 10 is substantially C-shaped in cross-section.

The outwardly facing surfaces of the gasket includes at least two opposed peaks 26, 28, 30, 32, 34, 36 spaced by a trough (or groove) 38, 40, 42, 44, 48. At least one of the peaks is located on the flanges. At least another of the peaks is located on opposite sides of the junction. There may be three or four or five or 6 or more peaks on each outwardly facing surface with troughs being located between adjacent peaks.

A line connecting the peaks 26, 28, 30, 32, 24 on each side of the gasket is straight. In other words, a first line connecting each of the peaks 26, 28, 30, 32, 24 included on the outwardly facing surface of one of the flanges 14 is straight, and a second line connecting each of the peaks 26, 28 30, 32, 24 included on the outwardly facing surface of the other of the flanges 16 is straight.

Each peak on one side extends equidistant from a centre line 50 of the gasket. Each peak on both sides may extend equidistant from the centre line. The grooves between at least two outer adjacent peaks are deeper than the groove between at least two peaks in a central region of the gasket on at least one and preferably both outwardly facing surfaces.

The grooves between at least two outer adjacent peaks on opposed side regions of at least one and preferably both outwardly facing surfaces are deeper than the grooves between two adjacent peaks in a central region.

The depth of the grooves between adjacent peaks reduces from one outer region coming into the central region and then increases from the central region to the other outer region.

The base of each groove is located on a common line 52 which line may be a curve and which may be an arc.

At least one of the peaks or all of the peaks on each outer surface is located on a line perpendicular to the centre line 50.

The distance between each adjacent peak on at least one outwardly facing surface, and preferably each such surface is equidistant.

At least one, and preferably all of the peaks includes a planar extent in cross section.

At least one of the grooves includes a curved or convex profile extending from a peak or forming the lower part of the groove or both. This may allow more of a soft sealant material to provide a greater seal at the centre of the radial sealing face when the flanges flex during compression and when the cavity is pressure energised that pressure will act on the flanges of the gasket, possibly with there being movement of the gasket.

The gasket 10 including the flanges 14, 16 the cavity 12, the junction 22 and the peaks and troughs are integrally formed and may be machined. The gasket includes soft sealant material 54 extending between at least two adjacent peaks on both sides and preferably between each adjacent peak on each side. The sealant material may be located in the grooves prior to compression of the gasket or when the gasket is pressurised.

Figure 3 shows one location where the gasket can be located to effect a seal. A conduit 56 defined between two flanges 58 and 60 is to be sealed. The flange 58 havs a cylindrical recess 62 defined in its inner portion. The depth of the recess is less than the height of the gasket at least when that height includes the sealant material 54.

When the flanges 58 and 60 are urged towards each other the sealant material 54 is subject to a compressive force. The sealant material 54 is subject to a greater compressive force or stress at a middle region, for instance between the peaks 30 and 32 than at one or both end regions, for instance between the peaks 26 and 28 or 34 and 36. This variation in force or stress may be a result of the curvature or convex profile of the troughs. Alternatively or additionally this may be because volume defined between the peaks and the trough in the middle region is less than the volume defined between the peaks 26 and 28 and the trough 38 at an outer region.

The cavity 12 between the flanges 14 and 16 faces the conduit 56. As pressure within the conduit 56 increases the pressure in the cavity 12 also increases. This increased pressure in the cavity 12 on the flanges 14 and 16 of the gasket to enhance the seal affected by the gasket.

Figures 4 and 5 show a gasket similar to that of Figures 1 to 3. Accordingly mainly the differences will be described.

The gasket 1 10 includes a cavity 1 12 that diverges outwardly away from the junction 122. The outwardly facing surfaces of the gasket include at least two opposed peaks 126, 128, 130, 132, 134 and 136 spaced by troughs (or grooves) 138, 140, 142, 144 and 146.

A line connecting the peaks of each side is straight. Those lines diverge from each other, for instance outwardly, away from the junction 122. Reference will now be made to Figures 6 to 9. Figure 6 is a view similar to Figure 3 with the exception that bolts that extend through openings 64 act to urge the flanges 58 and 60 towards each other. The flanges may be slightly spaced from each other when the bolts are tightened. Alternatively the flanges may abut each other when the bolts are tightened. Whilst the flanges 58 and 60 appear to be rigid they can nevertheless exhibit bending albeit to a very small degree. This bending may be due to the flimsiness of the flanges. Alternatively or additionally the bending may be due to an insufficiency of bolts acting to draw the flanges together.

Bending with a conventional gasket about the outer edge of the gasket is shown in

Figure 7. It can be seen that the movement or pivoting of flanges 58, 60 is considerable.

Compare Figure 7 with the bending of the flanges with a gasket according to the present idea. It can be seen in Figure 8 that the flanges pivot about a region spaced from the outer end regions of the gasket such as a mid region. That is relatively close to the conduit. Such pivoting or movement may be effected as a result of the compression forces or stresses of the sealant material being greater at the mid region than at the outer end region. Accordingly the effect of bending of the flanges is reduced with the gasket 10 or 1 10 and any loss of seal is less likely to occur with a gasket 10 than with a known gasket. Compare the outer pivot points P5 in Figure 7 of a conventional gasket and the mid region pivot point P6 with a gasket 10 in Figure 8.

The axis 64 that forms the arc 24 is located more towards the outer end of the gasket than the centre line 62 passing through the flanges 14 and 16.

Figure 9 shows an alternative way in which the flanges may be distorted. In this instance the outer extremes of the flanges may touch or be close to each other to form a dome. Pivoting may occur at points P7. With the gasket 1 10 that pivoting may be even nearer to the conduit as a result of the diverging lines connecting opposed peaks.

Whilst the gaskets have been shown with the cavity facing the conduit it will be appreciated that the gasket 10 or 1 10 could be formed in reverse, with the cavity opening on the outside of the gaskets. Such a form may be appropriate where the external pressure is greater than the internal pressure in the conduit. The gaskets 10 or 1 10 may comprise of stainless steel or a duplex stainless steel or may comprise or include a high nickel alloy such as inconel, hastelloy or may comprise or include titanium.

The sealant material 54 may comprise or include flexible graphite, PTFE or virgin PTFE or sigma modified filled PTFE or Thermiculite.

The distance between peaks on opposite sides of the gasket may be less than 6mm or less than 5mm or less than 4mm or less than 3.5 mm or more than 2mm or more than 2.5mm or more than 3 mm and may be 3.25 mm.

The depths of the gasket, without a sealant material, relative to the radial width of the gasket may be less than 4:1 or less than 3:1 or less than 2:1 or less than 1 :1 or more than 0.5:1 or more than 0.7:1 or more than 0.8:1 or more than 0.9:1 or in the region of 0.97:1 . Such dimensions may allow the gasket to fit within an O ring groove formed in at least one of two surfaces to be sealed.

The gasket is able to effect a seal under cryogenic temperatures and up to 1060°c although the gasket is not restricted to operating only within the upper temperature.

In an alternative embodiment (not shown) the gasket could be provided with an outer or inner guide ring which may be attached or loosely attached to the gasket. The loose attachment of the guide ring allows the gasket to move relative to the guide ring, for instance when the gasket is subject to compressive loads and when off loading effects may be present. This guide ring assists in locating the gasket in the correct area between two surfaces to be sealed. Alternatively or additionally the guide ring may provide a more positive compression stop and may prevent over compression of the gasket.

The material of the guide ring may be the same material as the gasket but may also be of different material than that of the gasket.

Whilst embodiments shown show the surfaces being sealed including a step in one of the surfaces it will be appreciated that the surfaces to be sealed could be planar surfaces without such a step. Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.