Large-pressure-difference bypass drain valve purging tool

Abstract

The utility model discloses a large-pressure-difference bypass drain valve purging tool, and relates to the field of bypass drain valve purging tools. In the industrial field, after a bypass discharge valve in a steam control system operates for a long time, a large number of sediments are attached to the interior of a valve body, the discharge efficiency is affected, equipment faults are possibly caused, and even potential safety hazards are caused. The valve seat purging device comprises a valve seat purging pressing plate, a seamless steel pipe and a valve cover purging pressing plate, the valve seat purging pressing plate is arranged at the upper end of a valve seat to seal a valve outlet runner in the middle of the valve seat, the seamless steel pipe is arranged on the valve seat purging pressing plate, and the valve cover purging pressing plate is arranged on the upper portion of an inner cavity of a valve body. A vertical through hole is formed in the middle of the valve deck purging pressing plate to communicate an inner hole of the seamless steel pipe with the outside of the valve body. Rectangular through holes are evenly distributed around the seamless steel pipe. Fluid is blown in multiple directions through the cuboid through holes in the pipe wall of the seamless steel pipe, attachments in the valve body are efficiently removed, and potential safety hazards of equipment are effectively reduced.

Description

Technical Field

[0001] This utility model relates to the field of bypass discharge valve purging fixtures, and in particular to a large differential pressure bypass discharge valve purging fixture. Background Technology

[0002] The upstream pipeline of the pressure reducing valve or desuperheater must be thoroughly cleaned before being put into use to ensure that there are no solid impurities, welding slag, or welding residues inside, in order to prevent blockage of the flow channel or mechanical damage to critical internal components. The cleaning process is usually carried out by high-pressure flushing or purging.

[0003] The existing purging process requires removing instruments and valves from the system before operation and using temporary short pipes in place. The original state is restored only after the purging is deemed satisfactory. This process easily leads to increased working hours, material waste, and safety hazards such as incomplete purging and residual media retention. Utility Model Content

[0004] The technical problem to be solved and the technical task proposed by this utility model is to improve and refine the existing technical solutions, and to provide a purging fixture for a large differential pressure bypass discharge valve, so as to achieve efficient removal of deposits inside the valve body. To this end, this utility model adopts the following technical solution.

[0005] A purging fixture for a large differential pressure bypass discharge valve is disclosed. The discharge valve includes a valve body, a valve seat, a labyrinth sleeve assembly, and an inlet flow channel. The inlet flow channel is located on the side of the valve body and communicates with the inner cavity of the valve body. The valve seat is located in the lower part of the inner cavity of the valve body and has an axial valve outlet flow channel in the middle. The labyrinth sleeve assembly is located below the valve seat. The purging fixture includes a valve seat purging plate, a seamless steel pipe, and a valve cover purging plate. The valve seat purging plate is located at the upper end of the valve seat to close the valve outlet in the middle of the valve seat. The seamless steel pipe is positioned above the valve seat purge plate, and the valve cover purge plate is positioned in the upper part of the valve body cavity, above the seamless steel pipe. The seamless steel pipe and the valve cover purge plate are vertically coaxial. A vertical through hole in the center of the valve cover purge plate connects the inner hole of the seamless steel pipe to the outside of the valve body. Multiple rectangular through holes with a vertical length are evenly distributed around the seamless steel pipe. The valve cover purge plate and the valve body are sealed by a self-sealing structure. After the fluid enters the cavity through the inlet channel, the valve cover purge plate moves upward under fluid pressure, pressing the self-sealing ring and the self-sealing pressure ring together to form a stable seal. At this time, the seamless steel pipe evenly sprays high-pressure fluid into the cavity, achieving multi-directional purging through the cuboid through-holes in the pipe wall. The sprayed high-pressure fluid forms a strong cleaning flow in the valve body cavity, effectively removing residues from the pipe, reducing equipment safety hazards, and improving equipment safety. Furthermore, there is no need to remove instruments and valves from the system before operation, thus improving efficiency.

[0006] As a preferred technical means: the self-sealing structure includes a self-sealing ring, a self-sealing pressure ring disposed on the self-sealing ring, and a four-ring disposed on the self-sealing pressure ring. The lower outer periphery of the valve cover purge plate is provided with an outer conical surface, and the inner side of the self-sealing ring is an inner conical surface that matches the lower outer conical surface of the valve cover purge plate. When the valve cover purge plate moves upward under the pressure of the fluid in the valve body cavity, the two conical surfaces press together to seal. When the valve cover purge plate moves upward under the pressure of the fluid, the two conical surfaces squeeze each other to form a tight seal. Compared with planar sealing, conical sealing can generate a larger sealing specific pressure under the same pressure, resulting in a better sealing effect. Moreover, the sealing performance improves with increasing fluid pressure. The self-sealing structure eliminates the need for manual adjustment during the sealing process, achieving automatic sealing by relying on the fluid's own pressure. This simplifies the operation process, reduces the difficulty of manual maintenance, and improves the convenience of using the purge fixture.

[0007] As a preferred technical approach, the self-sealing ring employs a metal-edged structure. This significantly enhances the high-temperature resistance and mechanical strength of the self-sealing ring. In industries such as petrochemicals and power generation, the operating environment of high-differential-pressure bypass discharge valves is high-temperature. Ordinary sealing rings are prone to failure due to high-temperature aging and deformation. The metal-edged self-sealing ring can maintain good elasticity and sealing performance under high-temperature environments, extending its service life. At the same time, the metal edging improves the sealing ring's wear and tear resistance, effectively resisting the impact of impurities in the fluid, reducing the risk of sealing ring damage, and further ensuring the stability and reliability of the purging tool sealing system.

[0008] As a preferred technical approach: the outer side of the four-ring is embedded in the upper inner groove of the valve body, and four radial holes are evenly distributed around the upper part of the valve body corresponding to the position of the inner groove. When it is necessary to disassemble the four-ring, it can be easily disassembled through the radial holes, which is simple and quick and improves maintenance efficiency. The four-ring, together with the self-sealing structure, can evenly distribute the pressure on the valve cover purging plate, prevent sealing failure caused by uneven pressure, enhance the stability of the self-sealing structure, and ensure the reliable operation of the entire purging fixture under high pressure conditions.

[0009] As a preferred technical approach: a lower flange of the valve cover pull ring is provided between the inner side of the four-ring and the valve cover purge plate. The upper outer side of the lower flange of the valve cover pull ring presses against the inner side of the upper end of the valve body through a downward step on its outer circumference. The lower middle outer circumferential surface of the lower flange of the valve cover pull ring is in contact with the inner circumferential surface of the four-ring, and the two are slidably matched. The inner circumference of the lower flange of the valve cover pull ring is tightly fitted with the outer circumference of the valve cover purge plate. While ensuring that the valve cover purge plate can float freely up and down to achieve self-sealing, its lateral displacement is restricted, so that the valve cover purge plate maintains stable operation under fluid pressure. In addition, this structural design enhances the connection strength between the various components of the tooling, improves the vibration and impact resistance of the entire purging tooling under complex working conditions, and extends the service life of the tooling.

[0010] As a preferred technical means: a valve cover pull ring round nut is provided on the upper part of the lower flange of the valve cover pull ring. The valve cover pull ring round nut is fixed to the outer periphery of the valve cover purge pressure plate by threads. Vertical limiting members are evenly distributed around the outer side of the valve cover pull ring round nut. The lower end of the vertical limiting member extends into the limiting groove provided at the upper end of the lower flange of the valve cover pull ring. When the outer conical surface of the valve cover purge pressure plate and the inner conical surface of the self-sealing ring are pressed together to seal the self-sealing, the lower end of the vertical limiting member abuts against the bottom of the limiting groove. The threaded fixing method ensures a reliable connection between the valve cover pull ring round nut and the valve cover purge pressure plate, preventing loosening during fluid pressure fluctuations or equipment vibration. The vertical limiting members limit the excessive upward movement of the valve cover purge pressure plate, avoiding damage to the sealing components or tooling structure due to excessive pressure, thus playing a protective role. At the same time, it ensures that the self-sealing structure works stably within a reasonable pressure range, improving the safety and reliability of the purge tooling operation.

[0011] As a preferred technical means: the valve seat purge plate is provided with a bottom groove, the upper end face of the valve seat is in contact with the top surface of the bottom groove of the valve seat purge plate, and a gap is provided between the upper outer diameter of the valve seat and the inner diameter of the bottom groove of the valve seat purge plate. This ensures that the valve seat purge plate effectively seals the valve outlet flow channel, preventing the purge fluid from leaking from the valve seat outlet, and also provides space for possible thermal expansion or installation errors between the valve seat and the valve seat purge plate, avoiding damage caused by rigid compression between components; the existence of the gap also facilitates the installation and disassembly of the valve seat purge plate, reducing installation difficulty, improving maintenance efficiency, and reducing friction between components, thus extending the service life of the valve seat and the valve seat purge plate.

[0012] As a preferred technical approach: the rectangular through holes are located in the middle of the seamless steel pipe along its height, with a total of four. The height of each rectangular through hole, i.e., its vertical length, is greater than half the height of the seamless steel pipe, and the width of each rectangular through hole is 2.2-3 times the distance between adjacent rectangular through holes. Limiting the position, number, and size of the rectangular through holes in the seamless steel pipe optimizes the purging effect, ensuring that high-pressure fluid can be evenly sprayed to all directions of the valve cavity, achieving omnidirectional purging and avoiding purging blind spots. The height of the rectangular through holes being greater than half the height of the seamless steel pipe ensures that the fluid spray has sufficient coverage and purging force, effectively removing impurities from the inner wall and components of the valve cavity. The width of the rectangular through holes within a specific range allows the fluid spray between adjacent holes to cooperate, forming a reasonable purging flow field, enhancing the flushing ability against stubborn impurities, improving the thoroughness and cleaning effect of the purging, and ensuring the normal operation of the high-pressure differential bypass discharge valve.

[0013] As a preferred technical means: the upper end of the valve seat purge plate is provided with an upper shallow groove, and the lower end of the seamless steel pipe is embedded and fixed in the upper shallow groove. The lower end of the valve cover purge plate is provided with a lower shallow groove, and the upper end of the seamless steel pipe is embedded in the lower shallow groove, with a gap between the outer diameter of the seamless steel pipe and the inner diameter of the lower shallow groove. This embedded installation method can accurately fix the position of the seamless steel pipe, ensuring its coaxiality with the valve seat purge plate and the valve cover purge plate, and ensuring the accuracy of the high-pressure fluid injection direction. When subjected to internal fluid pressure, the seamless steel pipe will not detach from the valve seat purge plate. At the same time, the gap between the outer diameter of the seamless steel pipe and the inner diameter of the lower shallow groove means that there is no fixed connection between the seamless steel pipe and the valve cover purge plate, which facilitates the upward movement of the valve cover purge plate when subjected to internal fluid pressure. It also provides space for the slight deformation of the seamless steel pipe under temperature changes or fluid pressure fluctuations.

[0014] Beneficial effects:

[0015] 1. The purging operation can be carried out without disassembling the valve, which effectively simplifies the process, avoids component wear or seal failure caused by disassembly and assembly, thereby improving purging efficiency and extending the service life of the valve.

[0016] 2. This tooling adopts a self-sealing structure design. During the purging process, the fluid pressure causes the valve seat purging plate and the valve cover purging plate to automatically fit together along the pressing direction, achieving a reliable seal.

[0017] 3. The tooling structure is simple, the components are compact, which facilitates quick installation and disassembly, and has good versatility and ease of maintenance. Attached Figure Description

[0018] Figure 1 This is a cross-sectional structural diagram of the present invention.

[0019] Figure 2 This is a cross-sectional view of the combination of valve seat purge plate, seamless steel pipe and valve cover purge plate in this utility model.

[0020] Figure 3 This is a 3D schematic diagram of the combination of valve seat purge plate, seamless steel pipe and valve cover purge plate in this utility model.

[0021] Figure 4 This is a utility model Figure 1 Enlarged schematic diagram of section A in the middle.

[0022] Figure 5 This is a schematic cross-sectional view of the valve seat purging pressure plate in this utility model.

[0023] Figure 6 This is a schematic cross-sectional view of the valve cover purge pressure plate in this utility model.

[0024] In the diagram: 1. Valve body; 2. Valve seat; 3. Labyrinth sleeve assembly; 4. Inlet flow channel; 5. Valve outlet flow channel; 6. Valve seat purge plate; 7. Seamless steel pipe; 8. Valve cover purge plate; 9. Self-sealing ring; 10. Self-sealing pressure ring; 11. Four-ring; 12. Valve cover pull ring lower flange; 13. Valve cover pull ring round nut; 14. Vertical limiting component; 15. C-ring sealing ring; 16. Valve seat pressure ring; 17. Sealing ring; 101. Radial small hole; 601. Bottom groove; 602. Upper shallow groove; 701. Rectangular through hole; 801. Lower shallow groove; 802. Outer conical surface; 803. Vertical through hole. Detailed Implementation

[0025] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings.

[0026] Example 1

[0027] like Figure 1-6 As shown, a purging fixture for a large differential pressure bypass discharge valve is provided. The discharge valve includes a valve body 1, a valve seat 2, a labyrinth sleeve assembly 3, and an inlet flow channel 4. The inlet flow channel 4 is located on the side of the valve body 1 and communicates with the inner cavity of the valve body 1. The valve seat 2 is fixed to the lower part of the inner cavity of the valve body 1 by threads. An axial valve outlet flow channel 5 is provided in the middle of the valve seat 2. The labyrinth sleeve assembly 3 is located below the valve seat 2. A sealing groove is provided between the valve seat 2 and the labyrinth sleeve assembly 3, and a metal C-ring sealing ring 15 is provided inside. A valve seat pressure ring 16 is provided on the outer side of the valve seat 2. A sealing ring 17 is provided between the lower end face of the valve seat pressure ring 16 and the outer stepped surface of the valve seat 2. The valve seat pressure ring 16 is fastened to the outer stepped surface of the valve seat 2 by a bolt, washer, and nut assembly.

[0028] The purging fixture includes a valve seat purging plate 6, a seamless steel pipe 7 for high-temperature boilers, and a valve cover purging plate 8. The valve seat purging plate 6 is located on the upper end of the valve seat 2 to close the valve outlet flow channel 5 in the middle of the valve seat 2. The seamless steel pipe 7 is located on top of the valve seat purging plate 6. The valve cover purging plate 8 is located on the upper part of the inner cavity of the valve body 1 and on top of the seamless steel pipe 7. The seamless steel pipe 7 and the valve cover purging plate 8 are vertically coaxial. The valve cover purging plate 8 has a vertical through hole 803 in the middle to connect the inner hole of the seamless steel pipe 7 and the outside of the valve body 1. The seamless steel pipe 7 has four rectangular through holes 701 that are vertically oriented around it to ensure purging of the cavity in all directions. The valve cover purging plate 8 and the valve body 1 are sealed by a self-sealing structure.

[0029] To achieve a self-sealing structure, the structure includes a self-sealing ring 9, a self-sealing pressure ring 10 on the self-sealing ring 9, and four open rings 11 on the self-sealing pressure ring 10. The four open rings 11 are four independent sector-shaped rings. The lower outer periphery of the valve cover purge plate 8 has an outer conical surface 802. The inner side of the self-sealing ring 9 is an inner conical surface that matches the lower outer conical surface 802 of the valve cover purge plate 8. When the valve cover purge plate 8 moves upward under the pressure of the fluid in the valve body 1, the two conical surfaces press together to seal. When the valve cover purge plate 8 moves upward under the pressure of the fluid, the two conical surfaces squeeze each other to form a tight seal. Compared with a planar seal, the conical seal can generate a larger sealing specific pressure under the same pressure, resulting in a better sealing effect. Moreover, the sealing performance improves as the fluid pressure increases. The self-sealing structure eliminates the need for manual adjustment during the sealing process, achieving automatic sealing based on the fluid's own pressure. This simplifies the operation process, reduces the difficulty of manual maintenance, and improves the ease of use of the purge fixture.

[0030] To ensure the valve cover purge plate 8 can float up and down, a valve cover pull ring lower flange 12 is provided between the inner side of the four-ring 11 and the valve cover purge plate 8. The upper outer side of the valve cover pull ring lower flange 12 presses against the upper inner side of the valve body 1 through a downward step on its outer periphery. The middle and lower outer circumferential surface of the valve cover pull ring lower flange 12 is in contact with the inner circumferential surface of the four-ring 11, and the two are in sliding engagement. The inner circumference of the valve cover pull ring lower flange 12 is tightly fitted with the outer circumference of the valve cover purge plate 8. While ensuring that the valve cover purge plate 8 can float freely up and down to achieve self-sealing, its lateral displacement is restricted, so that the valve cover purge plate 8 maintains stable operation under fluid pressure. In addition, this structural design enhances the connection strength between the various components of the tooling, improves the vibration and impact resistance of the entire purging tooling under complex working conditions, and extends the service life of the tooling.

[0031] To prevent the valve cover purge plate 8 from moving too high and damaging the self-sealing component, a valve cover pull ring round nut 13 is provided on the upper part of the valve cover pull ring lower flange 12. The valve cover pull ring round nut 13 is fixed to the outer periphery of the valve cover purge plate 8 by threads. Vertical limiting members 14 are evenly distributed around the outer side of the valve cover pull ring round nut 13. The lower end of the vertical limiting member 14 extends into the limiting groove provided at the upper end of the valve cover pull ring lower flange 12. When the outer conical surface 802 of the valve cover purge plate 8 and the inner conical surface of the self-sealing ring 9 press the self-sealing, the lower end of the vertical limiting member 14 abuts against the bottom of the limiting groove. The threaded fixing method ensures a reliable connection between the valve cover pull ring nut 13 and the valve cover purge plate 8, preventing loosening during fluid pressure fluctuations or equipment vibration. The vertical limiting member 14 restricts excessive upward movement of the valve cover purge plate 8, preventing damage to the sealing components or tooling structure due to excessive pressure, thus providing protection. It also ensures stable operation of the self-sealing structure within a reasonable pressure range, improving the safety and reliability of the purge tooling operation. In this embodiment, the vertical limiting member 14 is a bolt.

[0032] To facilitate installation and disassembly, the valve seat purge plate 6 has a bottom groove 601. The upper end face of the valve seat 2 is in contact with the top surface of the bottom groove 601 of the valve seat purge plate 6, and a gap is provided between the outer diameter of the upper end of the valve seat 2 and the inner diameter of the bottom groove 601 of the valve seat purge plate 6. This ensures that the valve seat purge plate 6 effectively seals the valve outlet flow channel 5, preventing the purge fluid from leaking from the outlet of the valve seat 2. It also provides space for possible thermal expansion or installation errors between the valve seat 2 and the valve seat purge plate 6, avoiding damage caused by rigid compression between components. The gap also facilitates the installation and disassembly of the valve seat purge plate 6, reducing installation difficulty, improving maintenance efficiency, and reducing friction between components, thus extending the service life of the valve seat 2 and the valve seat purge plate 6.

[0033] To optimize the purging effect, the rectangular through-hole 701 is located at the center of the seamless steel pipe 7 along its height. In this embodiment, the height of the rectangular through-hole 701, i.e., its vertical length, is 0.6 times the height of the seamless steel pipe 7, and the width of the rectangular through-hole 701 is 2.7 times the distance between adjacent rectangular through-holes 701. Limiting the position, number, and size of the rectangular through-holes 701 in the seamless steel pipe 7 optimizes the purging effect, ensuring that high-pressure fluid can be evenly sprayed to all directions of the valve cavity, achieving omnidirectional purging and avoiding purging blind spots. The height of the rectangular through-hole 701 is greater than half the height of the seamless steel pipe 7, ensuring that the fluid spray has sufficient coverage and purging force, effectively removing impurities from the inner wall and components of the valve cavity. The width of the rectangular through-hole 701 is within a specific range, allowing the fluid spray between adjacent holes to cooperate, forming a reasonable purging flow field, enhancing the flushing ability against stubborn impurities, improving the thoroughness and cleaning effect of the purging, and ensuring the normal operation of the high-pressure differential bypass discharge valve.

[0034] In order to accurately fix the position of the seamless steel pipe 7 and ensure its coaxiality with the valve seat purge plate 6 and the valve cover purge plate 8, the upper end of the valve seat purge plate 6 is provided with an upper shallow groove 602, and the lower end of the seamless steel pipe 7 is fitted and fixed in the upper shallow groove 602. The lower end of the valve cover purge plate 8 is provided with a lower shallow groove 801, and the upper end of the seamless steel pipe 7 is fitted in the lower shallow groove 801. A gap is provided between the outer diameter of the seamless steel pipe 7 and the inner diameter of the lower shallow groove 801. This embedded installation method can accurately fix the position of the seamless steel pipe 7, ensuring its coaxiality with the valve seat purge plate 6 and the valve cover purge plate 8, and ensuring the accuracy of the high-pressure fluid injection direction. When subjected to internal fluid pressure, the seamless steel pipe 7 will not detach from the valve seat purge plate 6. At the same time, the gap between the outer diameter of the seamless steel pipe 7 and the inner diameter of the lower shallow groove 801 means that there is no fixed connection between the seamless steel pipe 7 and the valve cover purge plate 8, which facilitates the upward movement of the valve cover purge plate 8 when subjected to internal fluid pressure. It also provides space for the slight deformation of the seamless steel pipe 7 under temperature changes or fluid pressure fluctuations.

[0035] During purging, fluid enters the valve body 1 through the inlet channel 4. Driven by fluid pressure, the valve cover purging plate 8 moves upward, pressing the self-sealing ring 9 and the self-sealing pressure ring 10 together to form a stable seal. At this time, the high-pressure fluid entering the seamless steel pipe 7 is purged in multiple directions through the rectangular through-hole 701, evenly sprayed onto the inner wall of the valve body 1. The ejected high-pressure fluid forms a strong cleaning flow within the valve body 1 cavity, efficiently removing deposits. Impurities are discharged upward with the fluid through the vertical through-hole 803 in the middle of the valve cover purging plate 8, thus completing the thorough cleaning of the valve body 1. After purging, the fluid pressure is released, the valve cover purging plate 8 returns to its original position, and the purging fixture is restored to standby status. The fixture can then be removed and the valve structure reinstalled, ensuring continuous and stable valve operation, effectively reducing equipment safety hazards and improving equipment safety. The overall design has fewer parts, a simple structure, and is easy to disassemble and assemble. This significantly reduces maintenance difficulty, thereby extending the valve's service life.

[0036] Example 2

[0037] Unlike the previous embodiment, the self-sealing ring 9 adopts a metal-edged structure. This significantly enhances the high-temperature resistance and mechanical strength of the self-sealing ring 9. In industries such as petrochemicals and power generation, the operating environment of high-differential-pressure bypass discharge valves is high. Ordinary sealing rings are prone to failure due to high-temperature aging and deformation. The metal-edged self-sealing ring 9 can maintain good elasticity and sealing performance in high-temperature environments, extending the service life of the sealing ring. At the same time, the metal edging improves the wear resistance and tear resistance of the sealing ring, effectively resisting the impact of impurities in the fluid, reducing the risk of sealing ring damage, and further ensuring the stability and reliability of the purging tool sealing system.

[0038] Example 3

[0039] Unlike embodiments one or two above, the outer side of the four-ring 11 is embedded in the upper inner groove of the valve body 1, and four radial holes 101 are evenly distributed around the upper part of the valve body 1 corresponding to the position of the inner groove. When it is necessary to disassemble the four-ring 11, it can be easily disassembled through the radial holes 101, which is simple and quick and improves maintenance efficiency. The setting of the four-ring 11, in conjunction with the self-sealing structure, can evenly distribute the pressure on the valve cover purging plate 8, prevent sealing failure caused by uneven pressure, enhance the stability of the self-sealing structure, and ensure the reliable operation of the entire purging fixture under high pressure conditions.

[0040] The above-described large differential pressure bypass discharge valve purging fixture is a specific embodiment of this utility model, which embodies the substantial features and progress of this utility model. Based on actual usage needs, equivalent modifications in shape, structure, etc., can be made to it under the guidance of this utility model, all of which are within the protection scope of this solution.

Claims

1. A purging fixture for a large differential pressure bypass discharge valve, wherein the discharge valve includes a valve body, a valve seat, a labyrinth sleeve assembly, and an inlet flow channel, the inlet flow channel being located on the side of the valve body and communicating with the inner cavity of the valve body, the valve seat being located in the lower part of the inner cavity of the valve body, and an axial valve outlet flow channel being provided in the middle of the valve seat, the labyrinth sleeve assembly being located below the valve seat, characterized in that: The purging fixture includes a valve seat purging plate, a seamless steel pipe, and a valve cover purging plate. The valve seat purging plate is located at the upper end of the valve seat to close the valve outlet flow channel in the middle of the valve seat. The seamless steel pipe is located on top of the valve seat purging plate. The valve cover purging plate is located in the upper part of the valve body cavity and is located on top of the seamless steel pipe. The seamless steel pipe and the valve cover purging plate are vertically coaxial. The valve cover purging plate has a vertical through hole in the middle to connect the inner hole of the seamless steel pipe and the outside of the valve body. The seamless steel pipe has multiple rectangular through holes that are vertical in length evenly distributed around it. The valve cover purging plate and the valve body are sealed by a self-sealing structure.

2. The purging fixture for a large differential pressure bypass discharge valve according to claim 1, characterized in that: The self-sealing structure includes a self-sealing ring, a self-sealing pressure ring disposed on the self-sealing ring, and a four-open ring disposed on the self-sealing pressure ring. The lower outer periphery of the valve cover purge plate is provided with an outer conical surface. The inner side of the self-sealing ring is an inner conical surface that matches the lower outer conical surface of the valve cover purge plate. When the valve cover purge plate moves upward under the pressure of the fluid in the valve body cavity, the two conical surfaces press together to seal.

3. The purging fixture for a large differential pressure bypass discharge valve according to claim 2, characterized in that: The self-sealing ring adopts a metal edge structure.

4. The purging fixture for a large differential pressure bypass discharge valve according to claim 3, characterized in that: The outer side of the four open rings is embedded in the upper inner groove of the valve body, and four radial small holes are evenly distributed around the upper part of the valve body corresponding to the position of the inner groove.

5. The purging fixture for a large differential pressure bypass discharge valve according to claim 4, characterized in that: A lower flange for the valve cover pull ring is provided between the inner side of the four-ring and the valve cover purge plate. The upper outer side of the lower flange for the valve cover pull ring is pressed and matched with the upper inner side of the valve body through a downward step on the outer periphery. The lower middle outer periphery of the lower flange for the valve cover pull ring is in contact with the inner periphery of the four-ring, and the two are slidably matched. The inner periphery of the lower flange for the valve cover pull ring is tightly matched with the outer periphery of the valve cover purge plate.

6. The purging fixture for a large differential pressure bypass discharge valve according to claim 5, characterized in that: The valve cover pull ring lower flange is provided with a valve cover pull ring round nut. The valve cover pull ring round nut is fixed to the outer periphery of the valve cover purge pressure plate by threads. Vertical limiting members are evenly distributed around the outer side of the valve cover pull ring round nut. The lower end of the vertical limiting member extends into the limiting groove hole provided at the upper end of the valve cover pull ring lower flange. When the outer conical surface of the valve cover purge pressure plate and the inner conical surface of the self-sealing ring are pressed together to seal, the lower end of the vertical limiting member abuts against the bottom of the limiting groove hole.

7. The purging fixture for a large differential pressure bypass discharge valve according to claim 6, characterized in that: The valve seat purge plate is provided with a bottom groove, the upper end face of the valve seat is in contact with the top surface of the bottom groove of the valve seat purge plate, and there is a gap between the upper outer diameter of the valve seat and the inner diameter of the bottom groove of the valve seat purge plate.

8. The purging fixture for a large differential pressure bypass discharge valve according to claim 7, characterized in that: The rectangular through holes are located in the middle of the height of the seamless steel pipe, and there are a total of 4. The height of the rectangular through holes, i.e. the vertical length, is greater than half the height of the seamless steel pipe, and the width of the rectangular through holes is 2.2-3 times the distance between adjacent rectangular through holes.

9. The purging fixture for a large differential pressure bypass discharge valve according to claim 8, characterized in that: The valve seat purge plate has an upper shallow groove at its upper end, and the lower end of the seamless steel pipe is fitted and fixed in the upper shallow groove. The valve cover purge plate has a lower shallow groove at its lower end, and the upper end of the seamless steel pipe is fitted in the lower shallow groove. A gap is provided between the outer diameter of the seamless steel pipe and the inner diameter of the lower shallow groove.

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