Improved Compression Seal Gas Gasket and Seal System

Abstract

Provided is an improved compression seal gasket and a seal system. **Solution**: The present invention relates to a compression seal gasket (14) including an annular body (18) made of an elastomer material and having an annular radially outer surface (20) and annular radially inner surfaces (22) that are parallel and coaxial to each other. At least one of the radially outer surface (20, 30) and the radially inner surface (22, 32) is made of metal or soft metal or PTFE and includes at least one first thin layer (23, 33) having a thickness between 1 nm and 1 mm.

Description

Technical Field

[0001] The present invention relates to a compression seal gasket designed to reduce permeability to gas and / or external water or steam.

[0002] This sealing gasket is used at the connection of two components in medium-voltage and high-voltage gas-insulated equipment.

Background Art

[0003] Some medium- and high-voltage devices are composed of hollow components in which conductors are arranged. An insulating gas is filled in these components, isolating the conductor that conducts high-voltage current from the hollow component at ground potential.

[0004] The insulating gas can also withstand the electric field at a short distance between the conductors arranged within the component.

[0005] The connection between two components includes, for example, the tubular parts of each component and a sealing gasket arranged between the tubular parts.

[0006] According to a known embodiment, the sealing gasket is made of an elastomer and is compressed between two components, such as two tubular parts or between one tubular part and a flat plate.

[0007] The compression of the two components causes the gasket to deform elastically, improving the airtightness of the connection.

[0008] However, the gasket is generally made of an elastomer that has permeability to the insulating gas.

[0009] One object of the present invention is to provide a sealing gasket having a significantly lower permeability in order to reduce the leakage rate of the complete device.

[0010] The purpose is to make the leakage rate of the entire power distribution device less than 0.5% vol / year, as described in the relevant IEC standards for switchgear, for example, IEC 62271-203 for gas-insulated switchgear.

[0011] This improvement is particularly interesting because the industry is transitioning to insulating gases containing different mixed gases or different gases, and the different properties of the new molecules used show different effects of leakage compared to the commonly used SF6 gas that has been used for decades.

[0012] In particular, a diluted gas in which heptafluoroisobutyronitrile is mixed with carbon dioxide and oxygen is being used as an alternative gas to SF6. CO2 has a strong tendency to leak. O2 and N2 also leak, but less than CO2. These three gases are more prone to leakage than SF6. The problem with these gas leaks is that, especially CO2 has an adverse impact on the environment. Furthermore, the lost gas has to be replaced, which incurs additional costs.

[0013] Another object of the present invention is to provide a sealing gasket having a significantly low permeability to heptafluoroisobutyronitrile and / or heptafluoroisopropyl trifluoromethyl ketone (also referred to as 2-butanone, 1,1,1,3,4,4,4-heptafluoro-3-(trifluoromethyl)-(CAS number 756-12-7)) and / or CO2 and / or O2 and / or N2 and / or water or water vapor, particularly in a gas-insulated device of the type described above or in the gas-insulated device of the present application, and more generally in high-voltage or medium-voltage components such as circuit breakers, switches, disconnectors, gas-insulated lines, and / or in gas-insulated devices implemented in medium-voltage or high-voltage applications. In fact, such gases include - Using heptafluoroisobutyronitrile alone or mixed with O2, CO2, N2 - and / or heptafluoroisopropyl trifluoromethyl ketone alone or mixed with O2 and / or CO2 and / or N2 - or CO2 alone or used in a mixture with O2 and N2 - N2 is used alone or mixed with O2 or CO2. Furthermore, since H2O is not desired inside such a device, another object of the present invention is to provide a sealing gasket that reduces or restricts or avoids the permeation of H2O (water and / or water vapor) from the outside of such a gas-insulated device implemented for medium-voltage or high-voltage applications.

Prior Art Documents

Patent Documents

[0014]

Patent Document 1

Summary of the Invention

[0015] The present invention relates to a gasket (or a sealing gasket, or a compression sealing gasket or a sealing system or a sealing gasket system or a compression sealing gasket system (any of these expressions can be used in the rest of this description)). The gasket includes an annular main body made of an elastomer material. The annular main body includes a radially inner face and a radially outer face. At least one of said radially inner face and said radially outer face comprises at least one first thin layer, made of, or comprising, a metal or a soft metal or PTFE).

[0016] Accordingly, at least one first thin layer is deposited or formed on at least part of said radially inner face and / or said radially outer face).

[0017] Said first thin layer is efficient against leaks of heptafluoroisobutyronitrile and / or heptafluoroisopropyl trifluoromethyl ketone (also named 2-butanone, 1,1,1,3,4,4,4-heptafluoro-3-(trifluoromethyl)- (CAS No 756-12-7)) and / or CO2 and / O2 and / or N2, in particular in applications implementing a gas, for example heptafluoroisobutyronitrile and / or heptafluoroisopropyl trifluoromethyl ketone (also named 2-butanone, 1,1,1,3,4,4,4-heptafluoro-3-(trifluoromethyl)- (CAS No 756-12-7)), possibly mixed with a dilution gas, which for example comprises carbon dioxide and oxygen and / or an oxygenated compounds, for example is composed at a pressure between 1 bar and 20 bar.for example at a pressure comprised between 1 bar and 20 bars).

[0018] It is also efficient against permeation of H2O (incoming water and / or water vapor).

[0019] Preferably, the first thin layer is: - has a thickness of between 1 nm and 1 mm, for example 300 nm or 1 μm; - and / or at least partially or completely covers at least one of said radially inner face and said radially outer face.

[0020] In a particular embodiment, each of the radially outer face and the radially inner face bears a thin layer of the above type.

[0021] In a more specific embodiment, - The first thin layer completely covers the radially outer face; and a thin layer, made of metal or PTFE and having for example a thickness of between 1 nm and 1 mm, partly or completely covers the inner face. - Or the first thin layer partly covers the radially outer face; and a thin layer, made of metal or PTFE and having a thickness of between 1 nm and 1 mm, completely or partly covers the inner face.

[0022] The main body may further comprise end faces which connect the radially inner face and the radially outer face, at least one of the end faces comprising a second thin layer of metal or soft metal or PTFE.

[0023] The second thin layer is: - may partly or completely cover at least one of said end faces. - and / or may have a thickness of between 1 nm and 1 μm.

[0024] In a gasket or a sealing gasket, or a compression sealing gasket or a sealing system or a sealing gasket system or a compression sealing gasket system according to the invention: - if at least one of said first thin layer and / or said second thin layer is made of, or comprises, metal or a soft metal, said metal or soft metal may be selected for example from among Ag, Al2O3, tin, Copper, Gold, Iron, or a mixture of these elements and / or any oxide of these elements; - If at least one of said first thin layer and / or said second thin layer is made of, or comprises, PTFE, said PTFE can be with or without charges (virgin or with filler(s)).

[0025] A gasket or a sealing gasket, or a compression sealing gasket or a sealing system or a sealing gasket system or a compression sealing gasket system according to the invention may comprise at least two superposed first thin layers of different materials, each one for example from the above list of metals or PTFE, one or both of them preferably having a thickness between 1 nm and 1 μm, the upper one being for example for protecting the underlying one; in a particular example, the underlying layer is or comprises a metal or a soft metal, for example from the above list, and the overlying layer protects the underlying layer against corrosion.

[0026] In an embodiment of a gasket or a sealing gasket, or a compression sealing gasket or a sealing system or a sealing gasket system or a compression sealing gasket system according to the invention, said radially outer face and said radially inner face can be parallel and / or coaxial to each other.

[0027] In another embodiment of a gasket or a sealing gasket or a compression sealing gasket or a sealing system or a sealing gasket system or a compression sealing gasket system according to the invention - at least one of said radially outer face and said radially inner face has a wavy or corrugated shape - and / or at least one end face has a wavy shape.

[0028] The invention also concerns a sealing system comprising two components, in which each of the components comprises an end or an assembly face that faces the end of assembly face of the other component and wherein a compression sealing gasket or a sealing gasket or a sealing system or a sealing gasket system or a compression sealing gasket system according to the invention is arranged and is compressed between the end or assembly faces of said components).

[0029] Said components or said sealing system may form part of a gas insulated portion of a high or medium voltage apparatus, said gas insulated portion): * containing, or being intended to contain, a gas, for example): - Mix heptafluoroisobutyronitrile and / or heptafluoroisopropyl trifluoromethyl ketone (also named 2-butanone, 1,1,1,3,4,4,4-heptafluoro-3-(trifluoromethyl)- (CAS No 756-12-7)), possibly with a gas or a dilution gas comprising at least CO2 and / O2 and / or N2 and / or an oxygenated compound and / or water vapor); - Or comprising at least CO2 and / O2 and / or N2 and / or an oxygenated compound and / or water vapor); * And / or said gas insulated portion or said apparatus being surrounded, or being intended to be surrounded, by an outer atmosphere containing some water and / or water vapor).

[0030] The invention also concerns a gas insulated portion of a high or medium voltage apparatus The gas insulated portion is * containing a gas, or being intended to contain, a gas, for example heptafluoroisobutyronitrile and / or heptafluoroisopropyl trifluoromethyl ketone (also named 2-butanone, 1,1,1,3,4,4,4-heptafluoro-3-(trifluoromethyl)- (CAS No 756-12-7)) possibly mixed with a gas or a dilution gas comprising at least CO2 and / O2 and / or N2 and / or an oxygenated compound and / or water vapor, or said portion containing a gas comprising at least CO2 and / O2 and / or N2 and / or an oxygenated compound and / or water vapor * and / or said gas insulated portion being surrounded, or being intended to be surrounded, by an outer atmosphere containing some water and / or water vapor).

[0031] Said apparatus further comprising a gas insulated portion according to the invention or two components, in which each of the components comprises an end or assembly face that faces the end or assembly face of the other component and wherein a gasket or a sealing gasket or a sealing system or a compression sealing gasket or a compression sealing gasket system according to the invention is arranged and is compressed between the end or assembly faces of the components).

[0032] Said components may be at least partly cylindrical and can be arranged coaxially to each other and to a main axis A, said end or assembly face of each component extending in a plane perpendicular to said main axis A.

[0033] Preferably, at least one of the end or assembly faces comprises an annular recess in which the compression sealing gasket according to the invention is fitted.

[0034] Preferably, the gasket according to the invention is axially compressed by the end or assembly faces.

[0035] The invention also concerns a method for insulating a gas insulated portion of a high or medium voltage apparatus. The gas insulated portion is * A gas, for example heptafluoroisobutyronitrile and / or heptafluoroisopropyl trifluoromethyl ketone (2-butanone, 1,1,1,3,4,4,4-heptafluoro-3-(trifluoromethyl)-(CAS number 756-12-7)) is optionally mixed with a gas or a dilution gas comprising at least CO2 and / or N2 and / or an oxygenated compound and / or water vapor, or said portion contains a gas comprising at least CO2 and / or N2 and / or an oxygenated compound and / or water vapor. * and / or said gas insulated portion being surrounded, or being intended to be surrounded, by an outer atmosphere containing some water and / or water vapor.

[0036] The said apparatus further comprises two components, in which each of the components comprises an end or an assembly face that faces the end or assembly face of the other component and wherein a gasket, or a sealing gasket, or a sealing system or a compression sealing gasket or a compression sealing gasket system according to the invention is arranged and is compressed between the end or assembly faces of the components).

[0037] Said gas can be contained in said apparatus at a pressure between 1 bar and 20 bars). Brief Description of the Drawings

[0038]

Figure 1

Figure 2A

Figure 2B

Figure 3

Figure 4

Figure 5A

Figure 5B

Figure 6

Mode for Carrying Out the Invention

[0039] FIG. 1 shows a part of a high-voltage device including components 10 combined with each other. Here, each component 10 is represented as a cylindrical and tubular component. It will be understood that the gasket 14, 14' according to the present invention, or a compression seal gasket, or a seal gasket, or a seal system, or a compression seal gasket system is applicable to a cylindrical component as shown in FIG. 1, or to components that may have other shapes, for example, as follows: - A non-cylindrical tubular part; or, - A non-tubular component, for example, a hole 100 in a gas chamber closed by a flange 101 (FIG. 6); the end face 111 of the flange faces the assembly face 102 of the gas chamber, and the assembly face 102 of the gas chamber is provided with a recess 16 for accommodating the gasket 14; alternatively, the recess may be partially or completely formed in the flange 101.

[0040] Alternatively, the gasket or compression sealing gasket or sealing gasket system or sealing system or compression sealing gasket system according to the invention can be used, for example, at the interface between two flanges.

[0041] The following description is made with reference to a tubular element, but the invention applies to any other pair of elements for which the interface must be sealed, particularly in the following respects: - Gases such as heptafluoroisobutyronitrile and / or heptafluoroisopropyl trifluoromethyl ketone (also known as 2-butanone, 1,1,1,3,4,4,4-heptafluoro-3-(trifluoromethyl)-(CAS number 756-12-7)) can be mixed, optionally, with a gas containing at least CO2 and / or N2 and / or an oxygen compound or a diluent gas; - Or a gas containing at least CO2 and / or O2 and / or N2 and / or an oxygen compound; - The interface is surrounded or is intended to be surrounded by outside air containing water and / or water vapor.

[0042] The gas can have a pressure between 1 bar and 20 bar, for example 5 bar or 15 bar.

[0043] In the following description, the elements represented are designated as parts 10, 10'.

[0044] Parts 10, 10' extend coaxially with the main axis AA' of the high-voltage device.

[0045] As can be seen in more detail in FIGS. 2A and 2B, each part 10 is composed of an end or assembly face 12 that faces and is connected to the end or assembly face 12' of the other part 10'.

[0046] The gasket or seal system for connecting components 10, 10' includes an annular gasket, or sealing gasket, or compression sealing gasket 14, 14', or sealing gasket, or sealing gasket system, or compression sealing gasket system, which is axially disposed between the end faces or mating surfaces 12, 12' of the two components 10, 10'. This gasket or seal system 14, 14' extends substantially in a plane perpendicular to axis AA'. In this embodiment and most of the following embodiments, the gasket has circular symmetry about axis AA'.

[0047] The sealing gasket or system includes tightening means 30, such as bolting means, which axially press one component 10 towards the other component 10'.

[0048] The tightening means 30 also axially compresses the sealing gaskets 14, 14' to provide a gastight connection between the two components 10, 10'.

[0049] According to a first embodiment represented in Figure 2A, the end faces or mating surfaces 12, 12' of each component 10, 10' form an annular recess 16 in which a part of the sealing gasket 14, 14' is received.

[0050] The axial depth of the recess 16 is less than half of the axial height of the gasket 14, 14' before the two components 10, 10' are assembled. As a result, before the components 10, 10' are finally assembled, the gasket 14, 14' projects axially from the end faces or mating surfaces 12, 12' of each component 10, 10'.

[0051] According to another embodiment shown in Figure 2B, the gaskets 14, 14' contact the end faces or mating surfaces 12, 12' of both components 10, 10' and keep the end faces or mating surfaces 12, 12' separated from one another.

[0052] The compression of the gaskets 14, 14' by the clamping means 30 causes axial deformation of the gaskets 14, 14' and maintains efficient pressure on the end faces or mating surfaces 12, 12' of the gaskets 14, 14' and on the wall surfaces and bottom surface of the recess 16.

[0053] The gaskets 14, 14' include a body or a main body 18, 38 made of a single material, for example, as a non-limiting example, an elastomer like, as a non-limiting example, the one known as unmodified butyl rubber or modified butyl rubber, for example chlorobutyl rubber (CIIR) or bromobutyl rubber.

[0054] The permeability of this elastomer to the gas filled in the component 10 results in gas loss over time.

[0055] As seen in FIGS. 3 and 4, the cross-section of the body 18, 38 of the gasket 14 along the axial plane including the main axis AA' can be of a general rectangular shape. Alternatively, it can also have a cross-section of an "O" ring or a circular cross-section.

[0056] Next, the bodies 18, 38 of the gaskets 14, 14' include annular radially outer faces 20, 30, annular radially inner faces 22, 32, and two planar annular end faces 24, 26, 34, 36 that axially partition the gaskets 14, 14' and connect the inner faces 22, 32 to the outer faces 20, 30.

[0057] According to a preferred embodiment, the surfaces 20, 22, 24 (FIG. 3) of the body 18 are formed in a wavy shape to enhance the sealing property. The wavy shape includes at least one protuberance or peak 24a and at least one recess or depression or valley 24b, 24c. The gas pressure brings a positive effect due to this complex shape: it increases the compression rate and the pressure presses the gasket towards the groove.

[0058] The surfaces 20, 22, 24 can have different shapes or be straight, as shown in FIG. 4. Alternatively, the gasket has the shape of an “O” ring, which also has an inner face and an outer face.

[0059] The inner part of the device with the gasket according to the present invention usually has the highest pressure P2 under the operating conditions (the outer pressure of the device is P1 < P2).

[0060] To reduce the air permeability of the gasket 14: * Heptafluoroisobutyronitrile and / or heptafluoroisopropyl trifluoromethyl ketone (2-butanone, 1,1,1,3,4,4,4-heptafluoro-3-(trifluoromethyl)-(CAS number 756-12-7)) and / or CO2 and / or O2 and / or N2, and / or water vapor (a gas, for example at pressure P2, like heptafluoroisobutyronitrile and / or heptafluoroisopropyl trifluoromethyl ketone (also named 2-butanone, 1,1,1,3,4,4,4-heptafluoro-3-(trifluoromethyl)- (CAS No 756-12-7)) and / or CO2 and / or O2 and / or N2, and / or to water vapor), * With respect to the incoming water and / or water vapor, at least one of the inner faces 22, 32 and the outer faces 21, 31 comprises a first thin layer 23 (and / or to incoming water and / or water vapor, at least one of the inner face 22, 32 and of the outer face 21, 31 comprises a first thin layer 23).

[0061] Preferably, the thickness of the thin layer is from 1 nm to 1 mm. Thus, only a small amount of material is required.

[0062] Said thin layer can be made of, or comprise, a metal or a soft metal. For example, such a technique may involve the spraying of 2 aerosols in aqueous phase, which will form a liquid film in which an oxidation-reduction reaction takes place after being in contact with the workpiece. This chemical reaction forms a uniform and homogeneous metal layer on the surface area of the workpiece.

[0063] The metal or soft metal can be selected, for example, from Ag, Al2O3, tin, copper, gold, iron, or mixtures of these elements and / or oxides of these elements.

[0064] Alternatively, the first thin layer 23 can be made of, or comprise, PTFE (PTFE, with or without charges).

[0065] Both the inner surfaces 22, 32 and the outer surfaces 20, 30 can each include a thin layer 21, 23 made of or comprising a metal or a soft metal (e.g., from the above list) or PTFE. Preferably, at least one or both of the thin layers 21, 23 have a thickness of 1 nm to 1 mm, for example 300 nm or 1 μm.

[0066] For example, there are Ag layers of 300 nm on the inner and outer surfaces respectively.

[0067] At least one of the flat end faces 24, 26, 34, 36 can be partially or completely made of, or covered by a thin layer made of or containing, metal or soft metal (such as from the above list) or PTFE. Preferably, the thin layer has a thickness between 1 nm and 1 mm. This enhances the gas tightness of the gasket against the above gases.

[0068] Figure 5A is a front view in a plane perpendicular to the axis (AA’) of a circular or annular gasket according to the invention. This gasket can have an inner diameter D1 configured, for example, between 30 mm and 1300 mm.

[0069] Alternatively, the gasket according to the invention also extends in a plane perpendicular to the axis (AA’), but has an elongated or elliptical or oval shape (Figure 5B) along the main axis BB’ (perpendicular to the axis AA’), which has a maximum inner dimension D2 that can be configured, for example, between 30 mm and 1300 mm.

[0070] In both Figures 5A and 5B, the radially inner face bears a thin metal layer 23 according to the invention. The axis AA’ is perpendicular to each of Figures 5A and 5B.

[0071] As already mentioned, in the axial plane containing the main axis AA’, the gasket body can have the shape of an “O” ring.

[0072] The present invention is applicable, for example, to a switch, or to a circuit-breaker, or to a disconnector, or to a transformer, or to a surge arresters, or to a gas-insulated line.

Explanation of Reference Numerals

[0073] 10, 10’: Parts 12, 12’: End faces or mating surfaces 14, 14’: Gasket / compression seal gasket / sealing gasket 16: Recess / annular recess 18, 38: Body part / main body 20, 30: Annular radially outer surfaces 21: Thin layer 22, 32: Annular radially inner surfaces 23: First thin layer 24, 26, 34, 36: Planar annular end faces 24a: Protrusion / peak 24b, 24c: Recess / depression / groove 31: Outer surface 33: Thin layer 100: Hole 101: Flange 102: Mating surface 111: End face AA’: Main axis

Claims

1. A sealing system comprising two parts (10, 10') that are part of a high-voltage or medium-voltage device containing gas, each part (10, 10') includes an end face or mating face (12) that faces the end face or mating face (12) of the other part (10), a compression seal gasket (14, 14') is compressed between the end faces or mating faces (12, 12') of the said parts (10, 10'), the compression seal gasket (14, 14') is made of an elastomeric material and includes a body (18, 38) having a radially outer face (20, 30) and a radially inner face (22, 32) coaxial with each other, at least one of the radially outer face (20, 30) and the radially inner face (22, 32) includes at least one first thin layer (23, 33) made of metal or soft metal or PTFE and having a thickness of 1 nm to 1 mm, a sealing system.

2. The sealing system according to claim 1, wherein the first thin layer at least partially covers at least one of the radially outer face (20, 30) and the radially inner face (22, 32).

3. The body (18, 38) further includes end faces (24, 26, 34, 36) connecting the inner face and the outer face, and at least one of the end faces includes a second thin layer of metal or soft metal or PTFE, the sealing system according to claim 1.

4. - The first thin layer completely covers the radially outer face (20, 30), is made of metal or soft metal or PTFE, and the thin layer having a thickness of 1 nm or more and 1 mm or less partially covers the inner face (22, 32), - Or, the first thin layer partially covers the radially outer face (20, 30), is made of metal or soft metal or PTFE, and the thin layer having a thickness of 1 nm to 1 mm completely covers the inner face (22, 32), the sealing system according to claim 3.

5. The second thin layer has a thickness of 1 nm or more and 1 µm or less, the sealing system according to claim 3.

6. The first thin layer and / or the second thin layer is made of a metal or a soft metal selected from Ag, Al ２ O ３ , tin, copper, gold, iron, or a mixture of these elements and / or an oxide of these elements, the sealing system according to claim 1.

7. The sealing system according to claim 1, wherein the radially outer face (20, 30) and the radially inner face (22, 32) are parallel and / or coaxial with each other.

8. - At least one of the radially outer face (20, 30) and the radially inner face (22) has a wavy shape - And / or, the sealing system according to claim 1, further comprising end faces (24, 26, 34, 36) at least one of which has a wavy shape.

9. The sealing system according to claim 1, wherein the first thin layer (23, 33) comprises or is made of a metal or soft metal having a thickness of 1 nm to 1 mm, or is covered by a thin layer that forms or contains a protective layer, such as a metal or soft metal or PTFE.

10. The sealing system according to claim 1, wherein the parts (10, 10') are at least partially cylindrical, arranged coaxially with each other and coaxially with respect to the main axis (AA'), and the end faces or mating faces (12, 12') of each part extend in a plane perpendicular to the main axis (AA').

11. The sealing system according to claim 10, wherein at least one of the end faces or mating faces (12, 12') includes an annular recess (16) into which the compression seal gasket (14, 14') is fitted.

12. The sealing system according to claim 1, wherein the gasket (14, 14') is axially compressed by the end faces or mating faces (12, 12').

13. A method for insulating a gas-insulated part of a high-voltage device or a medium-voltage device, wherein the gas-insulated part is * A gas, for example heptafluoroisobutyronitrile or heptafluoroisopropyl trifluoromethyl ketone (also known as 2-butanone, 1,1,1,3,4,4,4-heptafluoro-3-(trifluoromethyl)-(CAS number 756-12-7)), optionally containing CO ２ and / or O ２ and / or N ２ and mixed with a diluent gas containing and / or an oxygenated compound, or the portion contains at least CO ２ and / or O ２ and / or N ２ and / or a gas containing an oxygenated compound and / or water vapor * And / or, the gas-insulated part is surrounded by or is intended to be surrounded by an atmosphere containing some water and / or water vapor. The device and / or the gas-insulated part includes the sealing system according to any one of claims 1 to 11, or in two parts (10, 10'), each of the parts (10, 10') includes an end face or mating face (12, 12') facing the end face or mating face (12', 12) of the other part (10), and the compression seal gasket (14, 14') according to any one of claims 1 to 9 is arranged and compressed between the end faces or mating faces (12, 12') of the parts (10, 10').

14. The method according to claim 13, wherein the gas is contained in the device at a pressure (P2) between 1 bar and 20 bar.

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