GASKET

Abstract

A gasket for fluidly sealing two conduits having mating surfaces is described. The gasket includes an outer seal with a first thickness and an inner seal with a thickness greater than that of the outer seal. The inner seal can be compressed at least to the thickness of the outer seal. Methods of making the gaskets are also disclosed.

Claims

1. A gasket for fluidly sealing two conduits having mating surfaces, comprising: a core comprising top and bottom surfaces comprising a series of serrations; two sealing layers capable of fluidly sealing two conduits, wherein the core is between the two sealing layers; a deformable material capable of fluidly sealing two conduits, wherein the deformable material is adjacent to and radially inward from the sealing layers; wherein the deformable material has a thickness measured from a top surface to a bottom surface of the deformable material that is greater than a sealing layer/core thickness measured from a top surface to a bottom surface of the sealing layers; and wherein the thickness of the deformable material can be deformed at least to the sealing layer/core thickness.

2. The gasket of claim 1, wherein the deformable material is secured to the core.

3. The gasket of claim 1, further comprising a projection extending radially inward from a core inner surface and into the deformable material, wherein the projection secures the deformable material to the core.

4. The gasket of claim 1, wherein the deformable material has a compressability of 30% to 90%.

5. The gasket of claim 1, wherein the deformable material is more compressible than the sealing layers.

6. The gasket of claim 1, wherein the deformable material comprises polytetrafluoroethylene (PTFE).

7. The gasket of claim 1, wherein the deformable material comprises expanded PTFE.

8. The gasket of claim 1, wherein the core comprises stainless steel, a Monel alloy, or carbon steel.

9. The gasket of claim 3, wherein the projection comprises stainless steel, a Monel alloy, or carbon steel, and wherein the core comprises the same material as the projection.

10. The gasket of claim 1, wherein the two sealing layers comprise PTFE, graphite, a vermiculite-based sealing material, non-asbestos sheet, or soft metallic face.

11. The gasket of claim 1, wherein the gasket further comprises a chemical treatment agent within the deformable material, and wherein the chemical treatment agent is in contact with at least one mating surface when the gasket is compressed by the mating surfaces.

12. The gasket of claim 11, wherein the chemical treatment agent comprises a corrosion treatment agent.

13. The gasket of claim 11, wherein the chemical treatment agent is present in the deformable material in a range of 0.01% to 50% w/w.

14. A gasket for fluidly sealing two conduits having mating surfaces, comprising: an outer sealing means for compressibly forming a seal between two fluidly connected conduits; and an inner sealing means for compressibly forming a seal between two fluidly connected conduits, wherein the inner sealing means is radially inward from the outer sealing means, wherein the inner sealing means comprises an uncompressed thickness greater than an uncompressed thickness of the outer sealing means; and wherein the inner sealing means is deformable from the uncompressed thickness of the inner sealing means at least to the uncompressed thickness of the outer sealing means.

15. The gasket of claim 14, wherein the outer sealing means comprises a rigid core between two or more sealing layers.

16. The gasket of claim 14, wherein the inner sealing means comprises a projection from the rigid core into one or more deformable materials.

17. The gasket of claim 14, wherein the inner sealing means is more deformable than the outer sealing means.

18. The gasket of claim 14, wherein the inner sealing means comprises expanded polytetrafluoroethylene (PTFE).

19. The gasket of claim 14, wherein the outer sealing means comprises strength increasing means for improving sealing.

20. The gasket of claim 14, wherein the gasket further comprises a chemical treatment agent within the inner sealing means, and wherein the chemical treatment agent is in contact with at least one mating surface when the gasket is compressed by the mating surfaces.

21. The gasket of claim 20, wherein the chemical treatment agent comprises a corrosion treatment agent.

22. The gasket of claim 20, wherein the chemical treatment agent is present in the inner sealing means in a range of 0.01% to 50% w/w.

23. A gasket for sealing opposing flange surfaces of a pipe having corrosive fluid flowing there through comprising: a serrated profile core comprising a core thickness and a core inner surface; a projection extending radially inward from the core inner surface; a deformable material around the projection, wherein the deformable material extends radially inward from the core inner surface, inward beyond the projection such that the deformable material defines a gasket inner surface; and wherein the deformable material comprises a thickness greater than a thickness of the core.

24. The gasket of claim 23, wherein the core comprises stainless steel, a Monel alloy, or carbon steel.

25. The gasket of claim 23, wherein the deformable material comprises expanded PTFE.

26. The gasket of claim 23, further comprising sealing layers on the top and bottom surfaces of the serrated profile core.

27. The gasket of claim 26, wherein the sealing layers comprise PTFE, graphite, a vermiculite-based sealing material, non-asbestos sheet, or soft metallic face.

28. The gasket of claim 26, wherein the sealing layers and the core form an outer portion, wherein the deformable material and the projection form all or part of an inner portion, wherein when the outer portion and the inner portion are secured between opposing flange surfaces and deformed to an in-use thickness, the deformation of the inner portion is greater than the deformation of the outer portion.

29. The gasket of claim 28, wherein the inner portion is capable of forming a fluid seal between the gasket and the opposing flange surfaces.

30. The gasket of claim 28, wherein the outer portion is capable of forming a fluid seal between the gasket and the opposing flange surfaces.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0053] FIG. 1 is an exploded perspective view of a gasket of the present invention showing the separate components.

[0054] FIG. 2 is a side view of the assembled form of the gasket shown in FIG. 1.

[0055] FIG. 3 is a top view of a core portion of a gasket of the present invention having two proj ections.

[0056] FIG. 4 is a cross-sectional view of a gasket of the present invention having two projections.

DETAILED DESCRIPTION

[0057] Referring to FIGS. 1 and 2, a corrugated gasket core 2 is shown having a corrugated area 8 extending outwardly from an inner edge 10 defining a first aperture 14 to a plane surfaced outer area 12. FIG. 1 shows the core 2 prior to complete covering of the upper and lower surface of the corrugated area 8 with respective PTFE sealing rings 4, 6 having inner edges 16a, 16b which also define the first aperture 14 and outer edges 18(a), 18(b) which terminate at the outer edge of the corrugated area 8 when affixed to the surface of the core. FIG. 2 shows a side view of the assembled gasket. The core 2 includes handling lugs 20, 22 extending outwardly from the plane surface area 12 on opposite sides of the gasket core. Each lug 20, 22 is integral with the core and has a centrally disposed hole 32, 34 to accommodate a fixing bolt (not shown) when locating the gasket in the flange joint.

[0058] Referring to FIG. 3, a corrugated gasket core 202 is shown having a corrugated area 208 extending outwardly from an inner edge 210 defining an aperture 214 to a plane surfaced outer area 220. FIG. 3 shows the core without any sealing material covering the corrugated area and without a deformable inner portion. FIG. 3 shows two projections 236a, 236b extending radially inwardly from the inner edge 210 of the core 202. The projections are used to secure the core 202 to a deformable inner portion (not shown).

[0059] Referring to FIG. 4, a cross-section of a gasket is shown. The gasket has a corrugated core 202 similar to that shown in FIG. 3, and a corrugated area 208 extending outwardly from an inner edge 210 to a plane surfaced outer area 220. The core 202 is shown completely covered on the upper and lower surfaces of the corrugated area 208 with sealing material 204, 206 having inner edges 216a, 216b and outer edges 218a, 218b which may terminate at the outer edge of the corrugated area 208. The gasket includes an inner ring 224 defined by an inner edge 226, which itself defines an aperture 230 and an outer edge 228 adjacent to inner edges 216a, 216b, and 210. FIG. 4 shows two projections 236a, 236b extending radially inwardly from the inner edge 210 of the core 202. The projections 236a, 236b are used to secure the core 202 to a deformable inner portion 224.

[0060] The gasket includes an inner ring 24 defined by an inner edge 26 which itself defines a 2nd aperture 30 and an outer edge 28 which is shaped for close fitting engagement with the inner edges of the gasket core 10 and outer sealing rings 16(a) and 16(b). The axial depth of the inner ring 24 is roughly twice that of the assembled outer ring and it is located in such a manner that it extends beyond the surface of the outer ring equally in both axial directions.

[0061] In one embodiment, the inner ring 24 is made of expanded PTFE polymer which is microcellular in structure and which has been fully immersed in a rust inhibiting aqueous solution of sodium EDTA having a concentration of 200 g/m.sup.3.

[0062] In a further embodiment (not shown), the core includes four equally circumferentially spaced, radially inwardly extending projections, integral with the core and co-planar therewith at the axial ends thereof. The radially innermost end of the projection extends part way through the inner ring in the plane of the gasket to thereby secure the inner ring to the outer ring. The inner rings includes four matching circumferentially spaced sockets to accommodate each of the four projections in the inner ring.

[0063] In a still further embodiment (not shown), one of the lugs 20,22 includes a generally co-planar T-shaped extension secured at its base to the radially outermost edge of the lug by one or more frangible thin sections. The thin sections are strong enough to keep the extension attached to the main gasket during normal storage, transport and fitting conditions but weak enough to allow easy removal under a suitable generally axial force applied by the user after joint fixation.

[0064] In use, in one embodiment, the gasket is located between two mating parallel surfaces of a flange connection on a pipe connection wherein the surfaces of the flange have been corroded by prolonged exposure to sea water. As the mating surfaces are pressed together the deformable PTFE polymer of the inner is compressed and pushes into the crevices, scratches and pits in the surface of the flange providing sealing thereof and also delivering the sodium EDTA to the corroded areas. At the same time, the PTFE inner ring is also sealed against the undamaged areas on the surface and simultaneously treats those surfaces with rust inhibitor providing future resistance to rusting.

[0065] In one embodiment, the gasket is produced by cutting the appropriate gasket shape of the solid stainless steel core and machining a series of concentric serrations of increasing radii from the inner edge thereof which defines a first central aperture. The serrations are terminated before reaching the outer edge of the solid steel core so that an outer border of non-serrated profile is provided on the gasket. An annular ring of PTFE biaxially orientated compressible sealing material sized so as to fit over the serrated ring portion of the gasket is then cut and a suitable adhesive is applied to the inner face thereof. An annular ring of Sigma 500 PTFE is applied to both serrated areas on opposite faces of the core to thereby provide the outer gasket. An inner ring of highly compressible biaxially orientated PTFE, produced by impregnating a suitable sample of Sigma 600 available from Flexitallic with a rust inhibiting aqueous solution of sodium EDTA having a concentration of 200 g/m.sup.3 followed by drying is then cut having an outer edge of the same radius as the inner edge of the core and an inner edge which defines the 2nd aperture. Typically, the depth of the inner ring material is approximately twice that of the outer ring. In one embodiment, the depth of the inner ring is 6.5 mm and the depth of the outer ring is 3.5 mm made up of a 2 mm thick core and two facing layers each of 0.75 mm thickness. The depth of the serrations on the core is typically about 300 to 400 microns. For larger nominal pipe size flanges, or where out of flatness issues exist, the usage of thicker inner rings may be beneficial up to and including 10 mm. For certain flanges, the usage of a thicker core may also be advantageous.

[0066] In one embodiment, the metallic core is serrated in the area of application of the Sigma 500 material; in all other external areas outside the sealing contact areas the metallic core is protected and covered by a layer of Fluoro Polymer (FP) based coating this can optionally include the inner and outer edges of the metallic core. The sealing faces should be masked during coating to avoid contamination thereof. Generally, the FP coating is applied before the sealing layer. This FP offers additional environmental protections and, by use of a distinctive color, clear visibility on gasket installation when in usage. Advantageously, the covering of the outer edges by the FP polymer allows the user to see which flanges contain this gasket, and which flanges do not without opening the flange.

[0067] In one embodiment, the FP applied is IP9286 Red available from, for example, Indestructible Paint Ltd.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.