Self-tightening lightweight sealing structure

Abstract

The application discloses a self-tightening lightweight sealing structure, and belongs to the technical field of sealing, which is used for sealing the orifice of pressure-bearing equipment. The structure comprises a sealing support block, a gasket, a sealing pressure plate and a fastening assembly. The inner circumferential wall of the hole seat is provided with an annular supporting part. The sealing support block is supported in the hole seat. The gasket is arranged between the annular step part of the sealing support block, the inner circumferential wall of the hole seat and the sealing pressure plate. An axial allowance space is reserved between the sealing support block and the sealing pressure plate. When the equipment is running, the medium pressure on the inner side of the hole seat acts on the sealing support block, so that the sealing support block has a self-tightening tendency towards the sealing pressure plate, thereby compressing the gasket and making the gasket expand and tightly adhere to the inner circumferential wall of the hole seat in the radial direction. The structure can enhance the sealing effect by using the internal medium pressure, reduce the dependence on the installation pre-tightening torque accuracy, reduce the leakage risk, and has the effects of lightweight and convenient assembly, disassembly and maintenance.

Description

Technical Field

[0001] This application belongs to the field of sealing technology and relates to a self-tightening lightweight sealing structure. Background Technology

[0002] In pressure-bearing equipment such as nuclear island main equipment and chemical reactors, manholes or handholes serve as removable inspection and maintenance channels, and the performance of their sealing components directly determines the safety of the equipment. A common technical approach uses a structure of bolts, cover plates, and flat gaskets, relying on a high externally applied preload torque to compress and deform the gaskets. This typically involves a large number of bolts of significant size, and the cover plates and seat structures are bulky, increasing the workload of opening and sealing operations. Furthermore, under conditions of high temperature and pressure, temperature and pressure fluctuations, and frequent start-ups and shutdowns, gasket loosening and differences in thermal expansion between the bolts and the cover plate can easily cause preload attenuation, potentially leading to seal leaks. The sealing performance depends entirely on the accuracy of the preload torque applied during installation.

[0003] Therefore, there is a need to propose a sealing device that can achieve self-tightening function by utilizing internal medium pressure and has a lightweight structure. Summary of the Invention

[0004] The purpose of this application is to design a self-tightening lightweight sealing structure to solve the problems of insufficient sealing reliability and difficulty in loading and unloading due to structural weight in the existing technology.

[0005] Technical solution to achieve the purpose of this application: This application provides a self-tightening lightweight sealing structure for sealing pressure equipment, wherein the orifice of the pressure equipment has an orifice seat, characterized in that the self-tightening lightweight sealing structure includes a sealing block, a gasket, a sealing pressure plate, and a fastening assembly for connecting the sealing pressure plate to the orifice seat; The inner peripheral wall of the hole seat is provided with an annular support portion, and the sealing block is disposed in the hole seat and supported by the annular support portion; The sealing block is provided with an annular stepped portion for supporting the gasket, and the gasket is disposed between the annular stepped portion, the inner peripheral wall of the hole seat, and the sealing pressure plate; The sealing plate is fixed to the end of the hole seat and has a pressing part facing the gasket; An axial clearance space is reserved between the sealing support block and the sealing pressure plate, so that when the medium pressure inside the hole seat acts on the sealing support block, the sealing support block will have a self-tightening tendency towards the sealing pressure plate, thereby causing the gasket to be axially compressed and expanded radially outward against the inner peripheral wall of the hole seat.

[0006] Optionally, the gasket is located within an annular sealing accommodating area defined by the annular stepped portion of the sealing block, the inner peripheral wall of the hole seat, and the pressing portion of the sealing pressure plate, and the outer peripheral surface of the gasket and the inner peripheral wall of the hole seat form the main sealing mating surface.

[0007] Optionally, the sealing block includes an enlarged diameter portion near the inner side of the hole seat and a reduced diameter portion near the sealing pressure plate, with the enlarged diameter portion and the reduced diameter portion forming the annular step portion, and the gasket being sleeved on the outer side of the reduced diameter portion and supported on the annular step portion.

[0008] Optionally, the outer peripheral edge of the sealing block is provided with a chamfered or rounded transition structure to reduce the risk of scratching the gasket and the inner peripheral wall of the hole seat during assembly.

[0009] Optionally, the gasket is a resilient compression seal, and the cross-section of the gasket is rectangular, wedge-shaped, or approximately wedge-shaped.

[0010] Optionally, the gasket includes a graphite sealing body and a metal strip disposed at the axial end of the graphite sealing body, the metal strip being used to limit end extrusion of the graphite sealing body during installation, compression, or disassembly.

[0011] Optionally, the metal strip is respectively wrapped around the upper and lower end faces of the graphite sealing body.

[0012] Optionally, in the assembled state, an end face fit gap of no more than 0.05mm is formed between the end face of the sealing pressure plate and the end face of the hole seat, and an axial clearance gap of 1mm to 2mm is formed between the sealing pressure plate and the sealing support block.

[0013] Optionally, the sealing plate is provided with a flange, the inner end face of which constitutes the clamping part and is used to apply an initial axial clamping force to the gasket.

[0014] Optionally, the sealing plate has a hollow structure, which is located in the middle region of the sealing plate and avoids the connection area of ​​the fastening assembly.

[0015] Optionally, the fastening assembly includes a stud, a washer, and a nut. The stud passes through the sealing plate and is connected to the hole seat. The washer and the nut are disposed on the outside of the sealing plate to lock the sealing plate.

[0016] Optionally, the sealing plate is provided with through threaded holes that mate with the double-ended studs. The double-ended studs are arranged circumferentially around the hole seat, with a quantity of 4 to 16 sets and a thread specification of M12 to M45.

[0017] Optionally, the sealing block is provided with a lifting connection part, which is used to connect lifting eye bolts or lifting components to facilitate the installation and disassembly of the sealing block and the self-tightening lightweight sealing structure.

[0018] Optionally, the hoisting connection is located in the central area of ​​the sealing block.

[0019] Optionally, the orifice of the pressure vessel may be a human hole, hand hole, flushing hole, or inspection hole.

[0020] The beneficial technical effects of this application are as follows: The self-tightening lightweight sealing structure provided in this application is used for sealing orifices of pressure equipment. It features a sealing block supported by an annular support within the orifice seat, with a gasket positioned between the annular stepped portion of the sealing block, the inner circumferential wall of the orifice seat, and the sealing pressure plate. An axial clearance space is provided between the sealing block and the sealing pressure plate, allowing the internal medium pressure during equipment operation to act on the sealing block, pushing it towards the sealing pressure plate and creating a self-tightening tendency. This causes the gasket to be axially compressed and radially expanded to fit tightly against the inner circumferential wall of the orifice seat. Therefore, this application utilizes internal medium pressure to enhance the sealing effect, reducing the dependence of sealing performance on the accuracy of the installation pre-tightening torque. It mitigates the risk of leakage due to gasket loosening and pre-tightening force attenuation under high temperature and high pressure, temperature and pressure fluctuations, and frequent start-stop conditions. Furthermore, the structural cooperation of the sealing block, sealing pressure plate, and fastening components reduces structural weight and assembly / disassembly workload while ensuring sealing reliability, improving the ease of installation, disassembly, and maintenance of orifice sealing structures such as manholes, handholes, flushing holes, or inspection holes in pressure equipment. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a self-tightening lightweight sealing structure; Figure 2 A schematic diagram of a gasket with a self-tightening lightweight sealing structure; Figure 3 This is a schematic diagram of a sealing pressure plate for a self-tightening lightweight sealing structure.

[0022] In the picture: 1-Sealing support block, 2-Gasket, 3-Sealing pressure plate, 4-Double-ended stud, 5-Washer, 6-Nut, 7-Eye bolt, 8-Hole seat, 21-Graphite, 22-Metal strip, 31-Flange, 32-Through threaded hole, 33-Hollow structure. Detailed Implementation

[0023] To enable those skilled in the art to better understand this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only a part of the embodiments of this application, and not all of them. Based on the embodiments described in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] In this application, "inner side" can be understood as the side facing the internal medium pressure of the pressure-bearing equipment, and "outer side" can be understood as the side facing the outside of the equipment or the maintenance and operation space. When the equipment is running, the internal medium pressure of the pressure-bearing equipment acts on the sealing block 1 from the inner side, causing the sealing block 1 to move or be subjected to force in the direction of the sealing pressure plate 3, thereby achieving further compression of the gasket 2.

[0025] like Figures 1 to 3 As shown, this embodiment provides a self-tightening lightweight sealing structure for sealing the orifice of pressure equipment. The orifice of the pressure equipment has an orifice seat 8, and the inner peripheral wall of the orifice seat 8 is provided with an annular support portion. The self-tightening lightweight sealing structure includes a sealing block 1, a gasket 2, a sealing pressure plate 3, and a fastening assembly for connecting the sealing pressure plate 3 to the orifice seat 8. The fastening assembly may include a double-ended stud 4, a washer 5, and a nut 6.

[0026] The sealing block 1 is disposed within the bore seat 8 and supported by an annular support portion on the inner peripheral wall of the bore seat 8. The sealing block 1 includes an enlarged diameter portion near the inner side of the bore seat 8 and a reduced diameter portion near the sealing pressure plate 3, with an annular step portion formed between the enlarged diameter portion and the reduced diameter portion. This annular step portion is used to support the gasket 2, so that the gasket 2 can be stably arranged between the sealing block 1, the bore seat 8, and the sealing pressure plate 3.

[0027] Gasket 2 is an annular sealing element, fitted onto the outer side of the reduced-diameter portion of sealing block 1 and supported on the annular stepped portion of sealing block 1. Gasket 2 is located within the annular sealing accommodating area defined by the annular stepped portion of sealing block 1, the inner peripheral wall of the bore seat 8, and the pressing portion of sealing pressure plate 3. The outer peripheral surface of gasket 2 and the inner peripheral wall of bore seat 8 form the main sealing mating surface. After assembly, gasket 2 is subjected to the initial axial compression applied by sealing pressure plate 3, and can further undergo axial compression and radial expansion due to the pushing action of sealing block 1 during equipment operation, thereby improving sealing reliability.

[0028] In one embodiment, the gasket 2 is a resilient compression seal, and its cross-section can be rectangular, wedge-shaped, or approximately wedge-shaped. Preferably, the gasket 2 includes a graphite sealing body 21 and a metal strip 22 disposed at the axial end of the graphite sealing body 21. The metal strip 22 covers the upper and lower end faces of the graphite sealing body 21, respectively, to limit end extrusion of the graphite sealing body 21 during installation, compression, or disassembly. Further, the metal strip 22 can be made of 316L stainless steel, and its thickness can be from 0.3 mm to 0.5 mm.

[0029] The sealing plate 3 is fixed to the end of the bore seat 8. The sealing plate 3 has a flange 31 facing the gasket 2, and the inner end face of the flange 31 forms a clamping part for applying axial clamping force to the gasket 2 during initial installation. Through the flange 31, the gasket 2 can be pressed between the inner peripheral wall of the bore seat 8 and the annular stepped portion of the sealing block 1, thereby forming an initial seal.

[0030] The sealing plate 3 also has a through threaded hole 32 that mates with the double-ended studs 4. The double-ended studs 4 pass through the sealing plate 3 and connect to the seat 8. Washers 5 and nuts 6 are located on the outside of the sealing plate 3. Tightening the nuts 6 locks the sealing plate 3 to the end of the seat 8. The double-ended studs 4 can be arranged at intervals around the circumference of the seat 8, with a quantity of 4 to 16 sets and thread specifications ranging from M12 to M45. This connection method reduces the number of fasteners while ensuring initial clamping force, thus reducing the workload of assembly and disassembly.

[0031] To achieve weight reduction, a hollow structure 33 can be provided in the central area of ​​the sealing plate 3. The hollow structure 33 avoids the connection area of ​​the fastening components, reducing the amount of solid material used in the sealing plate 3 without affecting the connection strength and clamping function, thereby reducing the overall weight. Chamfered or rounded corners can also be provided at the sharp corners of the sealing support block 1 and the sealing plate 3 to reduce the risk of scratching the inner peripheral wall of the gasket 2 and the hole seat 8 during assembly. Preferably, the rounded corner radius can be 1mm to 3mm.

[0032] In the assembled state, a face clearance of no more than 0.05 mm can be formed between the end faces of the sealing plate 3 and the hole seat 8 to ensure the connection stability of the sealing plate 3 and the hole seat 8. An axial clearance space is reserved between the sealing plate 3 and the sealing block 1, preferably 1 mm to 2 mm. This axial clearance space provides room for the sealing block 1 to self-tighten towards the sealing plate 3 under the pressure of the internal medium during equipment operation, preventing premature rigid contact between the sealing block 1 and the sealing plate 3, which would weaken the self-tightening compression effect of the gasket 2.

[0033] A lifting connection can also be provided on the sealing block 1. The lifting connection is used to connect the eye bolt 7 or other lifting components to facilitate the installation, lifting, and disassembly of the sealing block 1 and the entire self-tightening lightweight sealing structure. Preferably, the lifting connection is located in the central area of ​​the sealing block 1 to make the lifting force more even and reduce the risk of the sealing block 1 tilting or getting stuck during the installation and disassembly process.

[0034] The installation process in this embodiment is as follows: First, the sealing block 1 is placed into the bore seat 8, so that the sealing block 1 is supported on the annular support portion on the inner circumferential wall of the bore seat 8; then, the gasket 2 is fitted onto the outside of the reduced diameter portion of the sealing block 1, and the gasket 2 is supported on the annular stepped portion of the sealing block 1; subsequently, the sealing pressure plate 3 is installed at the end of the bore seat 8, so that the flange 31 of the sealing pressure plate 3 faces the gasket 2; finally, the sealing pressure plate 3 is fastened to the bore seat 8 by the stud 4, washer 5, and nut 6. During the fastening process, the inner end face of the flange 31 applies an initial axial clamping force to the gasket 2, so that the gasket 2 is pressed between the inner circumferential wall of the bore seat 8 and the annular stepped portion of the sealing block 1, thereby forming an initial seal.

[0035] During equipment operation, the medium pressure inside the orifice seat 8 increases. This internal medium pressure acts on the sealing block 1, causing it to self-tighten towards the sealing pressure plate 3. Because an axial clearance space is provided between the sealing block 1 and the sealing pressure plate 3, the sealing block 1 can further apply axial compression to the gasket 2. After being axially compressed, the gasket 2 expands radially outward and further conforms to the inner circumferential wall of the orifice seat 8, thereby enhancing the sealing fit between the outer circumferential surface of the gasket 2 and the inner circumferential wall of the orifice seat 8. Therefore, the higher the internal medium pressure, the more pronounced the self-tightening effect of the sealing block 1 on the gasket 2. This reduces the dependence of the sealing effect on the accuracy of the installation pre-tightening torque and improves the sealing performance degradation caused by gasket loosening or thermal expansion differences under high temperature and high pressure, temperature and pressure fluctuations, and frequent start-stop conditions.

[0036] In a specific example, the self-tightening lightweight sealing structure is applied to the primary side manhole seal of a steam generator. The manhole seat 8 has an orifice size of Ф400mm. The sealing structure includes a sealing block 1, a gasket 2, a sealing pressure plate 3, a stud 4, a washer 5, a nut 6, and an eye bolt 7. The stud 4 can be M45, the washer 5 can be a washer compatible with M45 fasteners, the nut 6 can include a nut and a thin nut, and the eye bolt 7 can be M20.

[0037] In this specific example, the sealing block 1 has an overall cylindrical structure. Its bottom diameter near the inner side of the seat 8 is Ф428mm, and its top diameter near the sealing pressure plate 3 is Ф400mm, thus forming an annular stepped portion on the sealing block 1 to support the gasket 2. Both the top and bottom of the sealing block 1 are chamfered, with the top chamfer being 2mm × 45° and the bottom chamfer being 2mm × 10°. This chamfer design improves the ease of assembly of the sealing block 1 and reduces the risk of damage to the gasket 2 or the inner wall of the seat 8 during installation.

[0038] In this specific example, gasket 2 is an annular, resilient, compressible seal with a rectangular cross-section. Gasket 2 comprises a graphite sealing body 21 and a 316L metal strip 22, the metal strip 22 being 0.3 mm thick and covering the upper and lower ends of the graphite sealing body 21. The gasket 2 can be 27 mm thick before installation, and after installation, its thickness can be compressed to 25 mm under the pressure of the flange 31 of the sealing plate 3 to form a reliable initial seal.

[0039] In this specific example, the sealing plate 3 is connected to the end of the bore seat 8 by 16 sets of fastening components. The gap between the sealing plate 3 and the end face of the bore seat 8 is less than 0.05 mm, and the axial clearance between the sealing plate 3 and the upper surface of the sealing support block 1 is 1 mm to 2 mm. A hollow structure 33 is provided in the middle of the sealing plate 3 to reduce weight while ensuring connection and clamping functions. The sealing support block 1 and the sealing plate 3 can be made of the same material, both using Inconel 690 alloy. The thickness of the sealing support block 1 can be 90 mm, and the thickness of the sealing plate 3 can be 120 mm.

[0040] This specific example is applicable to operating conditions with a design pressure of 17.2 MPa, a design temperature of 350°C, and temperature and pressure fluctuations. Compared to the traditional sealing method that uses a manhole cover with a flat gasket and relies on a large number of high-preload fasteners, this embodiment can utilize the internal medium pressure to form a self-tightening seal. By reducing the thickness of the main components, setting a hollow structure 33 for the sealing pressure plate 3, and reducing the number of fasteners, overall weight reduction is achieved, and ease of disassembly and assembly is improved.

[0041] In another embodiment, the self-tightening lightweight sealing structure can also be used in the sealing structures of manholes, handholes, and flushing holes in steam generators in the nuclear energy field, as well as the sealing structures of pressurizer manholes. Different orifice structures can adopt the same self-tightening sealing principle and the same basic structural form, namely, all including an orifice seat 8, a sealing block 1, a gasket 2, a sealing pressure plate 3, and fastening components. Depending on the size of the orifice seat 8, the equipment pressure rating, and the installation space, the sizes of the sealing block 1, gasket 2, and sealing pressure plate 3, as well as the quantity and specifications of the fastening components, can be adjusted accordingly. Through the above standardized design, some fastener spare parts can be shared, thereby improving the convenience and economy of equipment maintenance.

[0042] The present application has been described in detail above with reference to the accompanying drawings and embodiments. However, the present application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present application. All content not described in detail in this application can be derived from existing technology.

Claims

1. A self-tightening lightweight sealing structure for sealing pressure equipment, wherein the orifice of the pressure equipment has an orifice seat (8), characterized in that, The self-tightening lightweight sealing structure includes a sealing block (1), a gasket (2), a sealing pressure plate (3), and a fastening assembly for connecting the sealing pressure plate (3) to the hole seat (8); The inner circumferential wall of the hole seat (8) is provided with an annular support portion, and the sealing block (1) is disposed in the hole seat (8) and supported by the annular support portion; The sealing block (1) is provided with an annular stepped portion for supporting the gasket (2), and the gasket (2) is disposed between the annular stepped portion, the inner peripheral wall of the hole seat (8), and the sealing pressure plate (3). The sealing plate (3) is fixed to the end of the hole seat (8) and has a pressing part facing the gasket (2); An axial clearance space is reserved between the sealing block (1) and the sealing pressure plate (3) so that when the medium pressure inside the hole seat (8) acts on the sealing block (1), the sealing block (1) tends to self-tighten towards the sealing pressure plate (3), thereby causing the gasket (2) to be axially compressed and expanded radially outward against the inner peripheral wall of the hole seat (8).

2. The self-tightening lightweight sealing structure according to claim 1, characterized in that, The gasket (2) is located in the annular sealing accommodating area defined by the annular stepped portion of the sealing block (1), the inner peripheral wall of the hole seat (8), and the pressing portion of the sealing pressure plate (3). The outer peripheral surface of the gasket (2) and the inner peripheral wall of the hole seat (8) form the main sealing mating surface.

3. The self-tightening lightweight sealing structure according to claim 1 or 2, characterized in that, The sealing block (1) includes an enlarged diameter portion near the inner side of the hole seat (8) and a reduced diameter portion near the sealing pressure plate (3). The enlarged diameter portion and the reduced diameter portion form the annular step portion. The gasket (2) is sleeved on the outer side of the reduced diameter portion and supported on the annular step portion.

4. The self-tightening lightweight sealing structure according to claim 3, characterized in that, The outer periphery of the sealing block (1) is provided with a chamfered or rounded transition structure to reduce the risk of scratching the inner periphery of the gasket (2) and the hole seat (8) during the assembly process.

5. The self-tightening lightweight sealing structure according to claim 1, characterized in that, The gasket (2) is a resilient compression seal, and the cross-section of the gasket (2) is rectangular, wedge-shaped or approximately wedge-shaped.

6. The self-tightening lightweight sealing structure according to claim 1, characterized in that, The gasket (2) includes a graphite (21) sealing body and a metal strip (22) disposed at the axial end of the graphite (21) sealing body, the metal strip (22) being used to restrict end extrusion of the graphite (21) sealing body during installation, pressure or disassembly.

7. The self-tightening lightweight sealing structure according to claim 6, characterized in that, The metal strip (22) covers the upper and lower surfaces of the graphite (21) sealing body, respectively.

8. The self-tightening lightweight sealing structure according to claim 1, characterized in that, In the assembled state, the end face of the sealing plate (3) and the hole seat (8) forms an end face fit gap of no more than 0.05mm, and the sealing plate (3) and the sealing block (1) form an axial clearance gap of 1mm to 2mm.

9. The self-tightening lightweight sealing structure according to claim 1, characterized in that, The sealing plate (3) is provided with a flange (31), the inner end face of which constitutes the pressing part and is used to apply an initial axial pressing force to the gasket (2).

10. The self-tightening lightweight sealing structure according to claim 1 or 9, characterized in that, The sealing plate (3) is provided with a hollow structure (33), which is located in the middle region of the sealing plate (3) and avoids the connection area of ​​the fastening assembly.

11. The self-tightening lightweight sealing structure according to claim 1, characterized in that, The fastening assembly includes a stud (4), a washer (5) and a nut (6). The stud (4) passes through the sealing plate (3) and is connected to the hole seat (8). The washer (5) and the nut (6) are located on the outside of the sealing plate (3) to lock the sealing plate (3).

12. The self-tightening lightweight sealing structure according to claim 11, characterized in that, The sealing plate (3) is provided with through threaded holes (32) that cooperate with the double-ended studs (4). The double-ended studs (4) are arranged circumferentially along the hole seat (8) in 4 to 16 groups, and the thread specifications are M12 to M45.

13. The self-tightening lightweight sealing structure according to claim 1, characterized in that, The sealing block (1) is provided with a lifting connection part, which is used to connect the lifting eye screw (7) or the lifting component, so as to facilitate the installation and disassembly of the sealing block (1) and the self-tightening lightweight sealing structure.

14. The self-tightening lightweight sealing structure according to claim 13, characterized in that, The hoisting connection is located in the central area of ​​the sealing block (1).

15. The self-tightening lightweight sealing structure according to claim 1, characterized in that, The pressure vessel openings are manholes, handholes, flushing holes, or inspection holes.

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