Valve sealing structure

Abstract

The invention provides a valve sealing structure, a valve comprises a valve body, a valve cover installed on the valve body, a valve plate located in the valve body and a transmission mechanism used for enabling the valve plate to move linearly, a first static sealing structure is arranged between the valve plate and the valve body, and a valve plate cover located on the low-pressure side of the valve plate is detachable. A second static sealing structure is arranged between a connecting flange of the valve body and a pipeline flange used for being connected with a pipeline, a third static sealing structure is arranged between the valve cover and the valve body, and a third static sealing structure is arranged in the valve body. The transmission mechanism converts rotary motion from the outside of the valve deck into linear motion and transmits the linear motion to the valve plate, and a dynamic sealing structure is arranged between the transmission mechanism and the valve body.

Description

Technical Field

[0001] The present invention relates to a valve sealing structure with high airtightness under special working conditions such as tritium vacuum environment, for example, it is suitable for gas on-off control systems in high vacuum, high permeability and strong radiation environments, such as controlled nuclear fusion reactors, tritium gas bottle operating platforms and other radioactive process systems. Background Art

[0002] Future large-scale fusion reactors (such as ITER and EAST), neutron generators, isotope neutron sources, and related industrial research fields all plan to use tritium as one of the essential materials. As an important radioactive fuel in fusion reactions, tritium fills the entire plasma discharge vacuum chamber of the tokamak device during the fusion reaction. Tritium is a radioactive substance with a physical half-life of approximately 12.3 years. During its decay, it releases weak beta rays and produces non-toxic helium-3. Due to its high permeability and chemical activity, tritium easily combines with hydrogen and oxygen in the environment to form tritiated water. Once inhaled or ingested by the human body, it can cause long-term internal radiation hazards. Therefore, tritium leakage must be strictly controlled.

[0003] On the other hand, global tritium reserves are extremely scarce, with commercial stocks measuring only tens of kilograms and a high unit price. Any equipment contamination caused by tritium leaks requires costly detritiation treatment, resulting in the loss of tritium resources. Therefore, tritium-related systems require gas sealing performance far exceeding conventional industrial standards, requiring ultra-high sealing control under the specialized operating conditions of high vacuum, high permeability, and strong radiation environments.

[0004] The existing high vacuum valve sealing structure mainly uses polymer (such as Viton rubber, etc.) elastic sealing rings and all-metal sealing rings. However, these two high vacuum valve sealing structures have obvious shortcomings in tritium-related working conditions: (1) Polymer elastic sealing rings have good compression resilience and economy, but their tritium barrier ability is limited, tritium molecule permeability is high, and they are prone to aging, making it difficult to meet the long-term sealing requirements in tritium-related environments; (2) All-metal sealing rings (such as metal C-type sealing rings) can provide good airtightness, but their manufacturing cost is high and their lifespan after repeated disassembly and assembly is limited, resulting in excessively high operating costs under test and normal working conditions. Therefore, in order to adapt to the special requirements of tritium-related environments for dynamic sealing and static sealing structures, an improved valve sealing structure that strikes a balance between reliability and economy is urgently needed. Summary of the Invention

[0005] The present invention aims to provide a valve sealing structure that can effectively cope with complex working conditions such as high vacuum, high permeability, and strong radiation, such as use in tritium-related environments, and can ensure the long-term stable operation of the valve system.

[0006] In order to achieve the above-mentioned objectives, the present invention provides a valve sealing structure, the valve comprising: a valve body, a valve cover installed on the valve body, a valve plate inside the valve body and a transmission mechanism for causing the valve plate to move linearly, a first static sealing structure is arranged between the valve plate and the valve body, the valve plate cover located on the low-pressure side of the valve plate is removable, so that a rubber sealing ring and a metal C-type sealing ring can be replaced for sealing, a second static sealing structure is arranged between the connecting flange of the valve body and the pipe flange for connecting the pipe, a third static sealing structure is arranged between the valve cover and the valve body, inside the valve body, the transmission mechanism converts the rotational motion from the outside of the valve cover into linear motion and transmits it to the valve plate, and a dynamic sealing structure is arranged between the transmission mechanism and the valve body.

[0007] As described above, the valve seal of the present invention utilizes multiple seals. Through a combination of static and dynamic seals, this ensures ultra-high sealing performance while also improving the overall durability of the sealing structure. Furthermore, by utilizing a replaceable structure in the first static seal between the valve plate and the valve body, the metal and rubber seals can be flexibly switched depending on the operating environment. This not only meets the sealing reliability requirements of tritium-related operations, but also balances cost-effectiveness and ease of operation during testing and normal operating conditions.

[0008] In one embodiment, a rubber seal ring, along with a first valve plate cover and a first pressure plate for mounting and securing the rubber seal ring, is used during testing and normal operating conditions. A metal C-ring, along with a second valve plate cover and a second pressure plate for mounting and securing the metal C-ring, is used during tritium-related environments. This ensures stable seal retention under various operating conditions, and allows for easy replacement of seal mounting components.

[0009] In one embodiment, the second static sealing structure between the connecting flange of the valve body and the pipe flange for connecting the pipeline uses a double-layer metal C-type sealing ring. A groove for installing two metal C-type sealing rings is formed in the connecting flange, and a third pressure plate is provided between the two metal C-type sealing rings. Metal C-type sealing rings are placed on both sides of the third pressure plate, and the interlayer space between the two metal C-type sealing rings is filled with leak-indicating gas. The metal C-type sealing ring has high-temperature stability and good elastic recovery performance under repeated opening and closing. It can still maintain excellent airtightness after long-term use in highly radioactive and permeable gas environments. Furthermore, by using a double-layer metal C-type sealing ring, a double sealing structure in series can be achieved. Even if a slight leak occurs in one layer of the seal, the other layer of the seal can be used to ensure the overall ultra-high sealing performance. In addition, by filling the interlayer space with leak-indicating gas, leak detection can be facilitated during operation, and the sensitivity and reliability of leak monitoring can be significantly improved.

[0010] In one embodiment, the third static seal structure between the valve cover and the valve body uses a double-layer indium wire. A groove for placing the indium wire is formed in one or both of the opposing surfaces of the valve cover and the valve body. Indium wires are placed in two grooves arranged side by side and spaced apart along the length of the valve cover, and the interlayer space between the two indium wires is filled with a leak-indicating gas. Indium wire is an ideal metal material for vacuum sealing due to its low vapor pressure, good deformability, and strong barrier to tritium. Moreover, by using a double-layer indium wire, a double sealing structure in series can be achieved. Even if a slight leak occurs in one of the sealing layers, the other sealing layer can be used to ensure the overall ultra-high sealing performance, thereby further reducing the leakage rate. In addition, by filling the interlayer space with a leak-indicating gas, leak detection can be facilitated during operation, and the sensitivity and reliability of leak monitoring can be significantly improved.

[0011] In one embodiment, the dynamic seal between the transmission mechanism and the valve body utilizes a double-layer bellows structure, comprising an outer bellows and an inner bellows. The outer and inner bellows concentrically surround the transmission mechanism, and the interlayer space between the outer and inner bellows is evacuated to a vacuum state. This effectively isolates the risk of tritium gas leakage.

[0012] In one embodiment, a rotation mechanism is provided outside the valve cover, and a transmission mechanism is linked to the rotation mechanism to convert the rotational motion of the rotation mechanism into linear motion of the valve plate, thereby achieving linear motion of the valve plate with a simple structure.

[0013] The above and other features, objectives and advantages of the present invention will become more apparent from the following detailed description and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 1 is a schematic three-dimensional diagram of the overall structure of a valve according to one embodiment of the present invention.

[0015] Figure 2 Schematic diagrams of the sealing structure between the valve plate and valve body according to one embodiment of the present invention. (a) shows the sealing structure using an O-ring under testing and normal operating conditions, and (b) shows the sealing structure using a metal C-ring under tritium-related environments.

[0016] Figure 3 Schematic diagram of a sealing structure between a connecting flange of a valve body and a pipeline flange according to one embodiment of the present invention.

[0017] Figure 4 The present invention is a partial cross-sectional view of a valve body according to one embodiment of the present invention. (a) shows a schematic diagram of the sealing structure between the valve cover and the valve body and the sealing structure of the transmission mechanism for the valve plate, and (b) shows an enlarged view of the sealing structure between the valve cover and the valve body.

[0018] Figure 5 is a system principle diagram according to one embodiment of the present invention.

[0019] Description of reference numerals:

[0020] 1: Valve; 2: Valve cover; 3: Valve body; 4: Valve plate; 5: Connecting flange; 6: Rotating mechanism; 7: O-ring; 8: First valve plate cover; 9: First pressure plate; 10: Fastener; 11: Metal C-ring; 12: Second valve plate cover; 13: Second pressure plate; 14: Pipe flange; 15: Fastener; 16: Third pressure plate; 17: Exhaust port; 18: Nut; 19: Stud; 20: Threaded fastener; 21: Indium wire sealing ring; 22: Screw; 23: Outer bellows; 24: Inner bellows; A: First static seal (part) between valve plate and valve body; B: Second static seal (part) between valve body connecting flange and pipe flange; C: Third static seal (part) between valve cover and valve body; D: Dynamic seal (part) of the valve plate transmission mechanism inside the valve body. DETAILED DESCRIPTION

[0021] In order to make the objectives, technical solutions and advantages of the present invention more clear, the technical solutions in the embodiments of the present invention will be described below with reference to the accompanying drawings.

[0022] Unless otherwise defined, all technical and scientific terms used in this invention have the same meanings as commonly understood by those skilled in the art to which this invention belongs. The terms used in the specification of this invention are only for the purpose of describing specific embodiments and are not intended to limit the invention. The terms "including" and "having" and any variations thereof in the specification of this invention and the accompanying drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification of this invention and the accompanying drawings are used to distinguish different objects, not to describe a specific order or a primary-secondary relationship.

[0023] In the description of the present invention, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" used in the present invention to indicate the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation.

[0024] When a component is referred to as being "connected to" or "in contact with" another component, the component may be directly connected to or in contact with the other component, or intervening components may be present. In contrast, when a component is referred to as being "directly connected to" or "in direct contact with" another component, there are no intervening components. Other terms used to describe the relationship between components should be interpreted in a similar manner (e.g., "between" versus "directly between," "adjacent" versus "immediately adjacent," etc.).

[0025] The present invention will be described below with reference to the accompanying drawings based on preferred embodiments thereof. In the following description of the drawings, identical or similar parts are marked with identical or similar reference numerals. The drawings are primarily schematic illustrations, and the proportions of various dimensions and the like may differ from actual proportions.

[0026] As mentioned above, special operating conditions, such as those involving tritium environments, require a novel valve sealing structure that balances ultra-high airtightness, radiation aging resistance, and long life. After extensive research, the inventors of this invention have designed a valve sealing structure with multiple seals. This structure, through a combination of static and dynamic seals, ensures ultra-high sealing performance while improving the overall durability of the sealing structure.

[0027] Moreover, in order to reduce costs, for the valve sealing structure of the present invention, the operator can easily replace part of the sealing structure, which not only meets the requirements of tritium-related operations for sealing reliability, but also takes into account the economy and ease of operation during the testing phase and normal working conditions.

[0028] The specific embodiments of the present invention are described in detail below based on the accompanying drawings.

[0029] Figure 1 : is a schematic three-dimensional diagram of the overall structure of a valve according to an embodiment of the present invention. Figure 1 As shown, the valve 1 of the present invention is a gate valve, which includes a valve body 3, a valve cover 2 installed on the valve body 3, a valve plate 4 inside the valve body 3, a connecting flange 5 of the valve body 3 for connecting to a pipeline, and a rotating mechanism 6, wherein the rotating mechanism 6 protrudes from the valve cover 2 (at Figure 1 The valve 1 is opened and closed by converting the rotational motion of the rotating mechanism 6 into the linear motion of the valve plate 4 in the valve body 3.

[0030] The sealing structure of the valve 1 according to one embodiment of the present invention includes three static seals and one dynamic seal. Figure 1 The figure shows the first static seal A between the valve plate and the valve body, the second static seal B between the valve body connecting flange and the pipe flange, the third static seal C between the valve cover and the valve body, and the dynamic seal D of the transmission mechanism of the valve plate inside the valve body (which is the internal structure of the valve body and will be shown in the cross-sectional view described later). Figures 2-4 The sealing structure of each part is explained in detail.

[0031] First of all, Figure 1 Part A in the figure is the first static seal between the valve plate 4 and the valve body 3, which is the main part of the sealing structure of the valve 1.

[0032] Figure 2 Schematic diagram of the sealing structure between the valve plate and the valve body according to one embodiment of the present invention, wherein (a) is a schematic diagram of the sealing structure using an O-type rubber sealing ring under testing and normal working conditions, and (b) is a schematic diagram of the sealing structure using a metal C-type sealing ring under tritium-related environment.

[0033] In the sealing structure between the valve plate 4 and the valve body 3, in order to be able to use both the O-type rubber sealing ring 7 under testing and normal operating conditions and the metal C-type sealing ring 11 under tritium-related environments as a sealing member, the valve plate 4 adopts a replaceable cover plate structure, that is, a removable valve cover plate is formed on the low-pressure side of the valve plate 4. Specifically, under testing and normal operating conditions, the valve plate 4 is fixed with a first valve plate cover 8 and a first pressure plate 9 that are compatible with the O-type rubber sealing ring by fasteners (such as bolts) 10. The O-type rubber sealing ring 7 is placed in the sealing groove formed by the first valve plate cover 8 and the first pressure plate 9. The first valve plate cover 8 and the first pressure plate 9 position and press the O-type rubber sealing ring 7. The O-type rubber sealing ring 7 can meet the sealing requirements under testing and normal operating conditions and can reduce the cost of use.

[0034] When valve 1 needs to operate in a tritium-containing environment, fastener 10 can be removed, first valve plate cover 8 and first pressure plate 9 can be disassembled, second valve plate cover 12, which is compatible with the metal C-ring, can be fixed to valve plate 4. Metal C-ring 11 can be placed in the mounting groove reserved in second valve plate cover 12 and pressed with second pressure plate 13, which is also compatible with the metal C-ring. Finally, fasten it with fastener 10 to complete the seal replacement. Metal C-ring 11 can meet the extremely high sealing requirements in special working conditions such as tritium-containing environments.

[0035] By selecting different seals according to needs in the sealing structure between the valve plate 4 and the valve body 3, the high requirements for sealing reliability in tritium-related operations can be met, while taking into account the economy and ease of operation during the test phase and normal working conditions.

[0036] Next, explain Figure 1 Part B is the second static sealing structure between the connecting flange 5 of the valve body 3 and the pipeline flange 14.

[0037] Figure 3 Schematic diagram of the sealing structure between the connecting flange of the valve body and the pipeline flange according to one embodiment of the present invention. Figure 3As shown, the second static seal between the connecting flange 5 and the pipe flange 14 uses a double-layer metal C-ring 11. A groove for mounting the two metal C-rings 11 is formed in the connecting flange 5. By using fasteners (such as bolts) 15 to install an adapted third pressure plate 16 on the connecting flange 5 between the two metal C-rings 11, and placing metal C-rings 11 on both sides of the third pressure plate 16, the installation stability of the double-layer metal C-ring 11 can be ensured. In addition, an exhaust port 17 is provided to evacuate the interlayer space between the two metal C-rings 11 and then introduce a leak-detecting gas (such as neon or argon), thereby facilitating leak detection during operation.

[0038] Metal C-rings are used in the sealing structures of Parts A and B described above. During the compression process, the soft metal on the surface of the metal C-ring undergoes plastic deformation, effectively filling the tiny pores on the sealing surface, while the built-in elastic metal acts as a rebound compensation, thereby achieving sealing. The metal C-ring has high-temperature stability and good elastic recovery performance under repeated opening and closing. It can still maintain excellent airtightness after long-term use in highly radioactive and permeable gas environments. Furthermore, by using a double-layer metal C-ring 11, a double sealing structure in series can be achieved. Even if a slight leak occurs in one layer of the seal, the other layer of the seal can be used to ensure the overall ultra-high sealing performance.

[0039] Next, explain Figure 1 Part C is the third static sealing structure between the valve cover 2 and the valve body 3, and part D is the dynamic sealing structure of the transmission mechanism of the valve plate 4.

[0040] exist Figure 4 In the figure, (a) shows a schematic diagram of the sealing structure C between the valve cover 2 and the valve body 3 and the dynamic seal D of the transmission mechanism of the valve plate 4, and (b) shows the sealing structure C in an enlarged manner.

[0041] like Figure 1 As shown, a plurality of threaded fasteners 20 consisting of nuts 18 and studs 19 are provided along the outer edge of the valve cover 2 to mount the valve cover 2 and the valve body 3 together. Figure 4 For simplicity, only two threaded fasteners 20 at both ends of the valve cover 2 in the longitudinal direction are shown in (a). In order to achieve a seal between the valve cover 2 and the valve body 3, a double-layer indium wire sealing structure is provided between the valve cover 2 and the valve body 3 and at both ends of the valve cover 2 in the longitudinal direction. Specifically, at the end of the valve cover 2 on the left side of the figure, a double-layer indium wire sealing structure is provided at a position to the right of the threaded fastener 20, and at the end of the valve cover 2 on the right side of the figure, a double-layer indium wire sealing structure is also provided at a position to the left of the threaded fastener 20. Figure 4(b) shows an enlarged view of the double-layer indium wire sealing structure on the left side of the figure. The double-layer indium wire sealing structure on the right side of the figure is identical. Two mounting grooves are arranged along the length of the valve cover 2 (i.e., left-right in the figure) and spaced at a predetermined interval on the surface of the valve body 3 facing the valve cover 2. An indium wire sealing ring 21 is positioned in each mounting groove, thereby forming a double-layer indium wire sealing structure. Furthermore, the interlayer space between the two indium wire sealing rings 21 is first evacuated to a vacuum environment through an exhaust port and then filled with a leak-detecting gas. Indium wire has excellent deformability. When the valve cover 2 and valve body 3 are fastened by bolts, the indium wire deforms dramatically, forming a large, close contact with the surfaces of the valve cover 2 and valve body 3. Furthermore, under high pressure, the indium surface cold welds to the metal surfaces of the valve cover 2 and valve body 3, forming a tight bond at the atomic level and achieving a leak-proof metal-to-metal seal. Therefore, due to its low vapor pressure, high deformability, and strong barrier properties to tritium, indium wire is an ideal material for vacuum sealing applications. Furthermore, the use of double-layer indium filaments enables a dual-seal structure in series. Even if a slight leak develops in one seal, the other seal ensures overall ultra-high sealing. Furthermore, by filling the interlayer between the double-layer indium filaments with a leak-detecting gas, the sensitivity and reliability of leak detection can be significantly improved.

[0042] In this embodiment, a structure in which a mounting groove and an indium wire sealing ring are provided on the surface of the valve body 3 facing the valve cover 2 is illustrated, but the present invention is not limited to this. A structure in which a mounting groove is provided on either or both of the opposing surfaces of the valve body 3 and the valve cover 2 and the indium wire sealing ring is clamped therebetween can be adopted.

[0043] like Figure 4 As shown in (a), the dynamic seal D of the transmission mechanism that causes the valve plate 4 inside the valve body 3 to perform linear motion adopts a double-layer bellows sealing structure. The valve body 3 is provided with a screw 22 connected to the rotating mechanism 6 located outside the valve cover 2, which is used to convert the rotational motion of the rotating mechanism 6 into linear motion of the valve plate 4. In the valve body 3, the outer bellows 23 and the inner bellows 24 are concentrically surrounded by the outer side of the screw 22. The pressure in the interlayer between the outer bellows 23 and the inner bellows 24 is pumped to 1×10 -1 Below Pa.

[0044] One end of the screw rod 22 passes through the valve cover 2 and is connected to the rotating mechanism 6 above the valve cover 2. The other end is connected to the valve plate 4. When the rotating mechanism 6 rotates clockwise, the screw rod 22 rotates clockwise in conjunction with it, driving the valve plate 4 at the other end toward the valve cover 2. The outer bellows 23 and the inner bellows 24 simultaneously contract, causing the valve to open. When the rotating mechanism 6 rotates counterclockwise, the screw rod 22 rotates counterclockwise accordingly, driving the valve plate 4 at the other end away from the valve cover 2. The outer bellows 23 and the inner bellows 24 simultaneously extend, causing the valve to close. After moving to the corresponding position, the valve plate 4 contacts and presses against the valve body 3, achieving a static seal. The valve body 3 is connected to the external pipeline through a static seal.

[0045] In the above-described embodiment, the screw rod 22 is used as the transmission mechanism in the valve body 3 . However, the present invention is not limited thereto, and any mechanism that can convert the rotational motion of the rotation mechanism 6 into the linear motion of the valve plate 4 may be used.

[0046] The above is the description of the multiple sealing structure used in the valve 1 of the present invention. Figure 5 is a system principle diagram according to one embodiment of the present invention.

[0047] like Figure 5 As shown, in the tritium-compatible valve sealing structure of the present invention that can be used in a tritium-related environment, there are three static seals and one dynamic seal. The static seals include: (1) a double-layer indium wire sealing structure between the valve cover 2 and the valve body 3, and a leak-indicating gas is passed into the interlayer of the double-layer indium wire sealing ring 21; (2) a replaceable sealing structure between the valve plate 4 and the valve body 3, which can use an O-type rubber sealing ring 7 under testing and normal working conditions, and a metal C-type sealing ring 11 under tritium-related environments, and the replaceable valve plate structure is compatible with multiple sealing rings, that is, when using the O-type rubber sealing ring 7, a matching first valve plate cover 8 and a first pressure plate 9 are used, and when using the metal C-type sealing ring 11, a matching second valve plate cover 12 and a second pressure plate 13 are used; (3) a double-layer metal C-type sealing ring sealing structure between the connecting flange 5 of the valve body 3 and the pipeline flange 14, and a leak-indicating gas is passed into the interlayer space of the double-layer metal C-type sealing ring 11. The dynamic seal is the sealing structure of the linear transmission mechanism of the valve plate 4. It uses a double-layer bellows for sealing, and the interlayer between the outer bellows 23 and the inner bellows 24 is vacuumed to a pressure of 1×10 -1 Below Pa.

[0048] The valve sealing structure of the present invention ensures reliable operation under tritium-related operating conditions, reduces the possibility of tritium leakage, and allows different leak-detecting gases to be introduced into the interlayer of the double-layer sealing ring without requiring repeated disassembly, significantly reducing the difficulty of leak detection during operation. Furthermore, this valve sealing structure takes both economic efficiency and reliability into consideration, with a replaceable valve plate. A metal C-ring is used under tritium-related operating conditions, while a rubber ring is used during testing and normal operating conditions. This reduces the cost of the valve under both testing and normal operating conditions while still meeting the requirements.

[0049] The leakage rate of the vacuum sealing interface of the tritium-related pipeline in the fusion reactor core is generally required to be less than 1×10 -10 Pa·m 3 / s, and the vacuum seal of tritium-related pipelines should meet the secondary containment principle. For example, the leakage rate of the all-metal valve produced by VAT Group is about 1×10 -11 Pa·m 3 / s. The leakage rate of the valve with the sealing structure of the present invention can reach 3×10 -12 Pa·m 3 / s, thus effectively coping with complex working conditions such as high vacuum, high permeability, and strong radiation, ensuring the long-term stable operation of the valve system, and reducing the leakage rate.

[0050] In the above-described embodiment, a gate valve is exemplified as the valve 1 , but the present invention is not limited thereto. The multi-seal structure of the present invention may also be employed in other types of valves, such as a swing valve.

[0051] The above describes the embodiments for implementing the present invention, but the present invention is not limited to the above embodiments. The above embodiments are merely examples, and embodiments having substantially the same structure and the same effects as the technical concept within the scope of the technical solution of the present invention are all included in the technical scope of the present invention. In addition, various modifications and combinations of elements of multiple embodiments within the scope of the present invention are also included in the scope of the present invention.

Claims

1. A valve sealing structure, characterized in that: The valve comprises: a valve body, a valve cover mounted on the valve body, a valve plate located inside the valve body, and a transmission mechanism for causing the valve plate to move linearly. A first static sealing structure is provided between the valve plate and the valve body. The valve plate cover located on the low-pressure side of the valve plate is detachable, so that a rubber sealing ring and a metal C-shaped sealing ring can be used interchangeably for sealing. A second static sealing structure is provided between the connecting flange of the valve body and the pipe flange for connecting the pipe. A third static sealing structure is provided between the valve cover and the valve body. Inside the valve body, the transmission mechanism converts the rotational motion from the outside of the valve cover into linear motion and transmits it to the valve plate. A dynamic sealing structure is provided between the transmission mechanism and the valve body.

2. The valve sealing structure according to claim 1, characterized in that: In the first static sealing structure arranged between the valve plate and the valve body, the rubber sealing ring and the first valve plate cover and the first pressure plate for installing and fixing the rubber sealing ring are used under testing and normal working conditions, and the metal C-type sealing ring and the second valve plate cover and the second pressure plate for installing and fixing the metal C-type sealing ring are used in a tritium-related environment.

3. The valve sealing structure according to claim 1 or 2, characterized in that: The second static sealing structure between the connecting flange of the valve body and the pipe flange for connecting the pipe uses a double-layer metal C-type sealing ring. A groove for installing the two metal C-shaped sealing rings is formed in the connecting flange, a third pressure plate is provided between the two metal C-shaped sealing rings, and the interlayer space between the two metal C-shaped sealing rings is filled with leak-indicating gas.

4. The valve sealing structure according to claim 1 or 2, characterized in that: The third static sealing structure between the valve cover and the valve body uses a double layer of indium wire. A groove for placing the indium wire is formed in either or both of the opposing surfaces of the valve cover and the valve body, and the indium wire is placed in two grooves arranged side by side and spaced apart along the length direction of the valve cover, respectively, and the interlayer space between the two indium wires is filled with leak-indicating gas.

5. The valve sealing structure according to claim 1 or 2, characterized in that: The dynamic sealing structure between the transmission mechanism and the valve body adopts a double-layer bellows structure including an outer bellows and an inner bellows. The outer bellows and the inner bellows concentrically surround the transmission mechanism, and the interlayer space between the outer bellows and the inner bellows is evacuated to a vacuum state.

6. The valve sealing structure according to claim 5, characterized in that: A rotation mechanism is provided on the outer side of the valve cover. The transmission mechanism is linked to the rotation mechanism. When the rotation mechanism rotates, the transmission mechanism can convert the rotational motion into a linear motion of the valve plate.

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