SEAL WITH ELECTRICALLY INSULATING COATINGS

Description

[0001] The present application claims benefit of and priority to U.S. Patent Application No. 15 / 726,080, filed October 5, 2017.BACKGROUND

[0002] Providing gaskets with electrically isolating properties is desired in a variety of different industries and applications. However, many limitations exist with respect to previously known gaskets having electrical isolating properties.

[0003] For example, in some cases, the electrical isolation properties of these gaskets are not high enough for a given application or industry. This may be because the material used to provide electrically isolating properties is not a high dielectric material.

[0004] In some instances, gaskets with electrically isolating properties are limited to lower temperature applications because they are not capable of withstanding exposure to high temperatures. In one example, gaskets with electrical isolating properties use glass reinforced epoxy (GRE). However, GRE has a maximum glass transition temperature in the range of from 250 to 350°F. When gaskets with GRE are exposed to temperatures above this range, the GRE becomes soft and rubber-like, and the GRE subsequently lacks the strength to properly support the sealing elements, thus leading to gasket failure. Additionally, GRE is typically adhered to a core of a gasket through the use of adhesive. This adhesive may fail at elevated temperatures and pressures, which can result in delamination.

[0005] Many gaskets incorporating materials having electrically isolating properties have larger thicknesses due to the material that is added to the core of the gasket in order to impart electrically isolating properties. Many common isolation materials have a dielectric strength value of between 400 and 800 volts / mil. Accordingly, a thick gasket is necessary to develop enough voltage resistance for common applications. These higher-thickness gaskets result in limitations on where the gaskets can be used.

[0006] Other problems associated with previously known gaskets having electrically isolating properties include structure complexity, limited dimensional stability, and limited chemical resistance. Thus, a need exists for an improved gasket having electrically isolating properties. CA 2 953 900 A1 discloses an electrically isolating gasket. US 5 407 214 A discloses a fire barrier gasket seal, according to the preamble of claim 1.SUMMARY

[0007] The invention is defined in claims 1 and 14. Further aspects and preferred embodiments are defined in the dependent claims. Any aspects, embodiments and examples of the present disclosure which do not fall under the scope of the appended claims do not form part of the invention and are merely provided for illustrative purposes.

[0008] Described herein are various embodiments of a gasket having electrically isolating properties. The gasket includes a core gasket component having a coating or film of dielectric material provided on the core gasket component. In some embodiments, the coating or film comprises polyimide, ceramic, or aluminum oxide. The coating or film is formed on all surfaces of the core gasket component, including on the surfaces of grooves formed in the axial surfaces of the core gasket component. A core gasket component fully encapsulated by the coating or film is also described herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a top plan view of a gasket according to various embodiments described herein. Figure 2A is a cross-sectional view of an example of the gasket shown in Figure 1 taken along line 2-2, this example not being in accordance with the invention. Figure 2B is a cross-sectional view of a gasket not in accordance with the invention. Figure 2C is a cross-sectional view of a gasket according to various embodiments of the invention described herein. DETAILED DESCRIPTION

[0010] With reference to Figure 1, a gasket 100 having improved electrically isolating properties according to various embodiments described herein is illustrated. The gasket 100 generally includes a core gasket component 110 (also referred to as a retainer) and a dielectric coating 120 formed on at least one surface of the core gasket component 110 (formed on at least the the top axial surface of the core gasket component 110 as shown in Figure 1). The core gasket component 110 includes one or more grooves formed in the axial surfaces of the core gasket component 110, with each groove optionally having a sealing element 130, 140 disposed therein.

[0011] The core gasket component 110 generally has a disc shape such that the gasket 100 is suitable for placement between, e.g., flanges of adjacent pipe segments. The dimensions of the core gasket component 110 (e.g., outer diameter, inner diameter, thickness between axial surfaces, etc.) are generally not limited and may be selected based on the specific application in which the gasket is to be used.

[0012] The material of the core gasket component 110 is generally not limited provided the core gasket component 110 is suitable for use in a gasket, including meeting or exceeding the properties required for the specific application in which the gasket 100 is used. The material of the core gasket component 110 will typically be an electrically conductive material since an object of the present application is to provide an electrically isolating coating to the core. In some embodiments, the material of the core gasket component 110 is a metal. In some embodiments, the material of the core gasket component 110 is stainless steel.

[0013] As noted above, the core gasket component 110 includes one or more grooves formed in one or more axial surface of the core gasket component 110. In some embodiments, the grooves are circular grooves aligned concentrically with the core gasket component 110, though other configurations can be used. In some embodiments, the grooves formed in one axial surface are identical to the grooves formed in the opposing axial surface, though other, non-symmetric configurations are also possible. In Figure 1, the core gasket component 110 includes two concentrically aligned grooves formed in at least a top axial surface of the core gasket component 110, with each groove having a sealing element 130, 140 disposed therein.

[0014] While grooves are specifically mentioned above and throughout this document, the core gasket component 110 may include raised features in addition to grooves. Raised features can be used to, for example, lock a seal in place or serves as stress concentrators.

[0015] With reference now to Figures 2A-2C, a cross-sectional view of the gasket 100 of Figure 1 taken along line 2-2 is shown, with each of Figures 2A, 2B, and 2C showing a different gasket 100. In Figure 2A (showing a gasket not in accordance with the invention), the dielectric coating 120 is formed on at least one surface of the core gasket component 110; in Figure 2B (showing a gasket not in accordance with the invention), the dielectric coating 120 is formed on at least one surface of the grooves 115 formed in the core gasket component 110; and in Figure 2C, in accordance with the invention, the dielectric coating 120 is formed on all surfaces of the core gasket component 110, including the surfaces of the grooves 115.

[0016] While not shown in any of Figures 2A-2C, the core gasket component 110 may also include one or more features that protrude away from the axial surfaces 111 of the core gasket component 110. In embodiments where such features are included, the dielectric coating 120 may be disposed on one or more surfaces of the raised features.

[0017] The specific number of grooves 115 provided in the core gasket component 110 is not limited. Furthermore, the cross-sectional shape, depth, width, and placement (e.g., radial distance away from the inner diameter) of each groove is generally not limited. As shown in Figures 2A-2C, two grooves 115 are included in each axial surface 111, the grooves 115 have a generally square cross-sectional shape, the grooves 115 are located in close proximity to the inner diameter of the core gasket component 110, and the grooves 115 formed in one axial surface are identical in shape, depth, and location to the grooves 115 formed in the opposing axial surface.

[0018] In some embodiments, the grooves 115 formed in the core gasket component 110 are used as sealing grooves. These sealing grooves are configured such that one or more sealing elements can be disposed within the sealing grooves 115. Any type of sealing element can be disposed in the sealing grooves 115, including for example E-rings, C-rings, O-rings, and spiral wound-type seals. In some embodiments, and as shown in Figures 2A-2C, an E-ring 130 can be disposed in the radially outer groove 115 and a lip seal 140 can be disposed in the radially inner groove 115.

[0019] In some embodiments, the grooves 115 are shaped and dimensioned such that only a single sealing element fits within the groove. For example, the radially outer groove 115 can be shaped and dimensioned such that an E-ring disposed therein occupies the entirety of the groove 115 and leaves no additional space for other components, such as a compression limiter. The groove 115 can be shaped and dimensioned in this manner because in the embodiments described herein, the gasket retainer (i.e., core gasket component 110) itself may act as the compression limiter, thereby eliminating the need for a separate compression limiter component being incorporated into the gasket 100.

[0020] The gasket 100 further includes a dielectric coating 120. As noted above, the dielectric coating 120 is applied to at least one surface of the core gasket component 110, either partially (such as is shown in FIGs. 2A and 2B, not in accordance with the invention) or, in accordance with the invention, completely covering the surface (such as is shown in FIG 2C) to which it is applied. As shown in FIG. 2C, the dielectric coating 120 is applied completely to every surface of the core gasket component 110, including the surfaces of grooves 115 (and any raised features) formed in / on the core gasket component 110. In other words, the dielectric coating 120 can be formed on the core gasket component 110 so as to fully envelope the core gasket component 110. In this manner, this dielectric coating 120 can electrically isolate the metallic core gasket component 110 and increase the range of applications in which the gasket 100 can be used.

[0021] In some embodiments, the dielectric coating 120 formed on the one or more surfaces of the core gasket component 110 is formed with a uniform thickness, including when the dielectric coating 120 is provided on all surfaces of the core gasket component 110. The thickness of the dielectric coating is generally not limited. In some embodiments, the thickness of the dielectric coating is in the range of less than 6 mm. In some embodiments, the thickness of the coating is 0.381 mm or less, such as 0.127 mm or less.

[0022] In some embodiments, the thickness of the dielectric coating 120 may vary, such as in a scenario where the thickness of the coating on the groove surfaces (or on raised feature surfaces) is less than the thickness of the coating on other surfaces (axial or radial) of the core gasket component 110. Alternatively, the thickness of dielectric coating on groove and / or raised feature surfaces can be greater than on the other surfaces of the core gasket component 110. The thickness of the dielectric coating can also vary from groove to groove.

[0023] In some embodiments, the dielectric coating 120 is polyimide, polyamide, ceramic, or aluminum oxide, with polyimide being a preferred material.

[0024] In some embodiments, the gasket 100, including any coating material, is free of glass reinforced epoxy (GRE).

[0025] The coating 120 may be applied to the core gasket component 110 using any known technique for applying a coating to a base substrate as long as the coating 120 is applied to the core gasket component 110 in a liquid form and then cured to form a solidified coating. In some embodiments, the curing is carried out in a continuous manner, which improves the throughput of the manufacturing process and makes the process more economically feasible. In some embodiments, the continuous curing process is carried out using a continuous infrared process or by continuously passing the core gasket component having liquid coating disposed therein through a convection oven. In some embodiments, the coating 120 is applied directly to the core gasket component 110 without the need for an intermediate adhesive or bonding layer.

[0026] The dielectric coating 120 being applied to all surfaces of the core gasket component 110 provides a gasket 100 that is electrically isolated from both any seals used with the gasket as well as from metallic flange surfaces that the gasket may be disposed between.

[0027] In some embodiments, the gasket described herein may further include an inner diameter seal, such as the inner diameter seal described in U.S. Published Application No. 2015 / 0276105. Other inner diameter seals may also be used.

[0028] The gasket described herein may be thinner, seal better, improve electrical isolation, and / or provide a more robust and reliable platform for fire-safe gaskets than previously known gasket materials. The gasket material described herein also advantageously eliminates any need for glass reinforced epoxy (GRE) in the gasket material. The gasket material described herein also provides stabilized material thickness and tolerance controls. The gasket material described herein expands the operating temperatures and electrical resistance of the product and allows for entry into new spaces of development, such as steam and nuclear service. The gasket described herein also expands pressure capabilities.

[0029] The gasket described herein further provides high dielectric strength, permeation resistance, tight tolerance capabilities, impact resistance, strong environmental protection, improved chemical resistance, and a simplified structure (i.e., less components to the overall gasket).

[0030] Problems that may be solved and / or advantages that may be achieved by the gasket described herein include, but are not limited to: improving electrical isolation properties of the dielectric components of the gasket through the use of high dielectric material; reducing external corrosion through complete encapsulation of the gasket retainer; increasing temperature ranges, allowing for use in wider variety of applications where current offerings of isolating gaskets include GRE; eliminating observed problem of failure of adhesive between GRE and retainer material commonly seen at elevated temperatures and pressures; decreasing gasket thickness and thereby allowing for use in a wider variety of applications through the use of thinner dielectric materials, which allows for ease in installation; decreasing the number of gasket components and thereby reducing complexity by eliminating, e.g., a backup ring compression limiting device as what is currently seen in similar isolating gasket configuration; increasing dimensional stability through use of materials that have controlled tolerances; increasing the ability to hold tight tolerances throughout the manufacturing process; improving sealing performance through the elimination of permeation in current gasket facing material as well as providing a more dimensionally stable gasket sealing surface; reducing exposed metal and electrical conduction points by being fully encapsulated in a dielectric material; providing a variety of coatings that can be applied for gasket use in a wider variety of applications; providing the ability to vary coating thickness to accommodate different applications and flange faces; eliminating GRE from the gasket; providing coatings that allow for better sealing in the event of exposure to media that is not compatible with GRE; controlling gasket colorations to thereby allow for different colors to signify different coatings; allowing for use of varied metallic retainers; metallic retainer coated with dielectric barrier will continue to act as compression limiter in the event of fire preventing leakage due to loss of stress of the gasket or possible expansion and over compression of the seal; non-permeable coating mitigates explosive decompression in systems where drastic pressure changes can occur; and; ability to utilize conductive sealing elements such as explosive decompression resistant O-rings.

[0031] The technology described herein is disclosed in the context of a gasket. However, the same principles can be applied to other types of pipe isolation components. For example, the features described herein, including coating a pipe isolation component partially or fully with a dielectric material such as a polyimide, could be applied to the flanges of a monolithic isolation joint, such as the ElectrosStop ®< Monolithic Isolation Joint manufactured by GPT of Wheat Ridge, CO.

[0032] From the foregoing, it will be appreciated that specific embodiments of the invention have been described herein for purposes of illustration, but that various modifications may be made without deviating from the scope of the invention. Accordingly, the invention is not limited except as by the appended claims.

Claims

1. An electrically isolating gasket (100) comprising: a metallic core gasket component (110), the core gasket component having a disc shape and including one or more grooves (115) formed in an axial face (111) of the metallic core gasket component; and a coating (120) comprising a dielectric material, characterized in that: the coating is formed on all surfaces of the metallic core gasket component including the surfaces of the grooves; and the coating is formed by being applied to the core gasket component in a liquid form and then cured to form the solidified coating.

2. The electrically isolating gasket of claim 1, wherein the core gasket component is made from stainless steel.

3. The electrically isolating gasket of claim 1, wherein the coating material is selected from the group consisting of polyimide, polyamide, ceramic, and aluminum oxide.

4. The electrically isolating gasket of claim 1, wherein the coating has a uniform thickness.

5. The electrically isolating gasket of claim 4, wherein the thickness is less than 6 mm, more preferably less than 0.381 mm, and most preferably less than 0.127 mm.

6. The electrically isolating gasket of claim 1, wherein the core gasket component includes a radially outer groove and a radially inner groove in a first axial surface of the core gasket component, and a radially outer groove and a radially inner groove in the second axial surface of the core gasket component, wherein the grooves in the first axial surface are concentrically aligned and the grooves in the second axial surface are concentrically aligned.

7. The electrically isolating gasket of claim 6, wherein the diameter of the radially outer groove in the first axial surface is equal to the diameter of the radially outer groove in the second axial surface, and the diameter of the radially inner groove in the first axial surface is equal to the diameter of the radially inner groove in the second axial surface.

8. The electrically isolating gasket of claim 7, wherein a sealing mechanism (130, 140) is disposed in each of the radially outer groove in the first axial surface and the radially outer groove of in the second axial surface.

9. The electrically isolating gasket of claim 8, wherein the radially outer groove in the first axial surface and the radially outer groove in the second axial surface are each sized and dimensioned such that the sealing mechanism disposed therein occupies all of the groove.

10. The electrically isolating gasket of claim 8, wherein the sealing mechanism is selected from one of an E-ring (130), a C-ring, an O-ring and a spiral wound-type seal.

11. The electrically isolating gasket of claim 6, wherein a lip seal (140) is disposed in each of the radially inner grooves in the first axial surface and the radially inner groove of the second axial surface.

12. The electrically isolating gasket of claim 1, wherein the thickness of the coating on the surfaces of the grooves is less than the thickness of the coating on the other surfaces of the core gasket component.

13. The electrically isolating gasket of claim 1, wherein the electrically isolating gasket is a glass reinforced epoxy-free electrically isolating gasket.

14. A method of manufacturing an electrically isolating gasket (100) according to claim 1 comprising coating every surface of a disc-shaped core gasket component (110), including the surfaces of one or more grooves (115) formed in or on the core gasket component, with a liquid coating comprising a dielectric material; and continuously curing the liquid coating to harden the liquid coating and secure the coating (120) to the disc-shaped gasket component.

15. The method of manufacturing an electrically isolating gasket of claim 14, wherein continuously curing the liquid coating comprises continuously exposing the liquid coating to infrared radiation.