Marine stop valve and assembling method thereof

Abstract

The invention belongs to the technical field of valves, and particularly relates to a marine stop valve and an assembling method thereof. The marine stop valve comprises a valve body, a valve clack, a guide sleeve, a valve rod, a hand wheel, a valve cover and a locking assembly, wherein a main channel and a secondary channel are arranged in the valve body; the valve clack is arranged in the main channel; the guide sleeve is arranged at an upper port of the main channel, and annular sealing structures are arranged on the outer circumferential surface and the inner circumferential surface of the guide sleeve; the valve rod comprises an upper valve rod and a lower valve rod, the lower valve rod penetrates through the guide sleeve and is connected with the valve clack, and the lower end of the lower valve rod is limited in the main channel by the guide sleeve; the lower end of the upper valve rod is connected with the lower valve rod, and the upper end penetrates through the valve cover and then is connected with the hand wheel; the locking assembly comprises a bolt, a nut and a double-folding self-locking gasket, the bolt penetrates through the valve deck and is in threaded connection with the valve body, the nut is assembled on the bolt in a threaded mode and located above the valve deck, and the double-folding self-locking gasket abuts against the position between the nut and the valve deck. The stop valve for the ship is not prone to damage and has excellent reliability.

Description

Technical Field

[0001] This application belongs to the field of valve technology, and more specifically, relates to a marine gate valve and its assembly method. Background Technology

[0002] As a core component of fluid control systems, valves directly determine the sealing performance, durability, and operational safety of pipeline systems through their structure and installation process. With the upgrading of manufacturing technologies and the continuous improvement of engineering safety standards, the industry's demand for innovation and optimization of valve structures and related installation processes is becoming increasingly urgent.

[0003] In related technologies, marine valves not only need to withstand vibrations, tilting, and impact loads generated during ship navigation, but also need to resist the direct impact of the medium within the pipeline system. Therefore, the requirements for the valve's anti-loosening performance are extremely stringent. However, traditional valves are prone to loosening and failure due to vibration during long-term operation, and also suffer from complex installation processes, low positioning accuracy, and unstable sealing effects, resulting in poor valve reliability. Therefore, improvements are urgently needed. Summary of the Invention

[0004] In view of the deficiencies or improvement needs of the prior art, this application provides a marine gate valve and its assembly method, which aims to solve the problem of poor reliability of traditional valves.

[0005] This application provides a marine gate valve, specifically comprising a valve body, a valve disc, a guide sleeve, a valve stem, a handwheel, a valve cover, and a locking assembly, wherein: The valve body has an axially penetrating main channel and a secondary channel that bypasses the main channel; the valve disc is located in the main channel; the guide sleeve is located at the upper port of the main channel and is positioned by the valve cover and the valve body; both the outer and inner circumferential surfaces of the guide sleeve are provided with annular sealing structures. The valve stem includes an upper valve stem and a lower valve stem. The lower valve stem passes through the guide sleeve and is connected to the valve disc. The lower end of the lower valve stem is restricted within the main channel by the guide sleeve. The lower end of the upper valve stem is connected to the lower valve stem, and its upper end passes through the valve cover and is connected to the handwheel. By pulling the handwheel, the valve stem drives the valve disc to move axially, which can adjust the opening and closing between the main channel and the secondary channel. Multiple locking components are distributed around the valve stem. Each locking component includes a bolt, a nut, and a double-layered self-locking washer. The bolt passes through the valve cover and is threadedly connected to the valve body. The nut is threaded onto the bolt and located above the valve cover. The double-layered self-locking washer is pressed between the nut and the valve cover.

[0006] As a further preferred embodiment, the upper valve stem includes a pull rod section and a push rod section. The lower end of the pull rod section is connected to the upper end of the lower valve stem. The outer peripheral surface of the pull rod section is slidably fitted to the inner peripheral wall of the valve cover. The lower end of the push rod section is detachably connected to the upper end of the pull rod section. The upper end of the push rod section passes through the valve cover and is connected to the handwheel.

[0007] As a further preferred embodiment, the top rod section is fitted with an upper anti-friction pad, which is located between the valve cover and the handwheel.

[0008] As a further preferred embodiment, the outer periphery of one end of the top rod section located inside the valve cover protrudes to form a flange, and a lower friction-reducing pad is sandwiched between the flange and the inner wall of the valve cover.

[0009] As a further preferred embodiment, the lower valve stem is threadedly connected to the valve disc.

[0010] As a further preferred embodiment, the marine shut-off valve also includes a locking element, wherein the lower valve stem and the valve disc are locked and fixed by the locking element.

[0011] As a further preferred embodiment, both the outer and inner circumferential surfaces of the guide sleeve are provided with annular grooves, and the annular sealing structure is embedded in the annular grooves.

[0012] The second aspect of this application provides a method for assembling a marine gate valve, which adopts the following technical solution: An assembly method for a marine gate valve includes the following steps: S1. Pre-processing the components of the marine shut-off valve, the pre-processing including visual inspection, grinding of sealing surfaces and cleaning; S2. Install an annular sealing structure on the outer and inner circumferential surfaces of the guide sleeve, and then assemble the valve disc, lower valve stem, and guide sleeve together and insert them into the main channel of the valve body; S3. Connect the upper valve stem to the lower valve stem, and fit the valve cover onto the outer periphery of the upper valve stem; S4. A locking assembly is used to connect the valve cover to the valve body; S5. Connect the handwheel to the upper valve stem to assemble a marine shut-off valve.

[0013] As a further preferred embodiment, in step S4, the locking assembly is installed using a diagonal cross-fastening method.

[0014] In summary, compared with the prior art, the technical solutions conceived in this application have the following main technical advantages: The marine gate valve of this application effectively improves its reliability by optimizing the connection structure between the valve stem and valve disc, and by adding anti-friction gaskets and double-layered self-locking gaskets. Meanwhile, the matching design of the annular sealing structure and guide sleeve helps enhance the pressure resistance and service life of the marine gate valve, while the locking assembly uses a diagonal cross-fastening method to ensure uniform force on the valve cover and a stable connection. With this design, the marine gate valve of this application has a compact overall structure, simple assembly process, and is easy to maintain, making it suitable for the fluid control needs of high-frequency operation and harsh working conditions in marine pipeline systems. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of a marine gate valve provided in an embodiment of this application; Figure 2 This is an exploded view of a marine shut-off valve provided in an embodiment of this application; Figure 3 This is an exploded view of the valve disc, locking element, and lower valve stem provided in the embodiments of this application; Figure 4 This is a schematic diagram of the lower valve stem provided in an embodiment of this application; Figure 5 This is a schematic diagram of the valve body provided in the embodiment of this application; Figure 6 This is a schematic diagram of the valve cover provided in an embodiment of this application; Figure 7 This is a top view of the valve cover provided in an embodiment of this application; Figure 8 yes Figure 5 Enlarged view of point A in the middle; Figure 9 This is a schematic diagram of the structure of the guide sleeve provided in an embodiment of this application; Figure 10 yes Figure 9 Enlarged view of point B in the middle; Figure 11 This is a schematic diagram of the assembly of the guide sleeve and the annular sealing structure provided in the embodiments of this application; Figure 12 This is an assembly drawing of the valve disc, locking element, and lower valve stem provided in the embodiments of this application; Figure 13 This is a diagram showing the assembly sequence of the locking components provided in the embodiments of this application; Figure 14 This is a schematic diagram of the structure of the double-layered self-locking gasket provided in the embodiments of this application; Figure 15 This is a schematic diagram of a handwheel with a protective structure provided in an embodiment of this application; Figure 16 This is a schematic diagram of a valve body with a protective structure provided in an embodiment of this application.

[0016] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1. Valve body; 2. Valve disc; 3. Guide sleeve; 3-1. Annular sealing structure; 4-1. Upper valve stem; 4-1a. Pull rod section; 4-1b. Push rod section; 4-2. Lower valve stem; 5. Handwheel; 6. Valve cover; 7. Locking assembly; 7-1. Bolt; 7-2. Nut; 7-3. Double-layered self-locking gasket; 8. Upper anti-friction gasket; 9. Lower anti-friction gasket; 10. Locking element; 11. Protective structure. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0018] The following is in conjunction with the appendix Figures 1-16 This application will be described in further detail.

[0019] This application discloses a marine shut-off valve. (Refer to...) Figure 1 and Figure 2 The marine gate valve includes a valve body 1, a valve disc 2, a guide sleeve 3, a valve stem, a handwheel 5, a valve cover 6, and a locking assembly 7. The valve body 1 has an axially penetrating main channel and a secondary channel that bypasses the main channel. The valve disc 2 is located in the main channel. The guide sleeve 3 is located at the upper end of the main channel and is positioned by the valve cover 6 and the valve body 1. Both the outer and inner circumferential surfaces of the guide sleeve 3 are provided with annular sealing structures 3-1. The valve stem includes an upper valve stem 4-1 and a lower valve stem 4-2. The lower valve stem 4-2 passes through the guide sleeve 3 and is connected to the valve disc 2. The lower end of the lower valve stem 4-2 is restricted within the main channel by the guide sleeve 3. The lower end of the upper valve stem 4-1 is connected to the upper end of the lower valve stem 4-2. The upper end of the upper valve stem 4-1 passes through the valve cover 6 and is connected to the handwheel 5. By pulling the handwheel 5, the valve stem drives the valve disc 2 to move axially, which can adjust the opening and closing between the main channel and the secondary channel. There are multiple locking components 7 distributed around the valve stem. The locking components 7 include bolts 7-1, nuts 7-2 and double-layered self-locking washers 7-3. Bolts 7-1 pass through the valve cover 6 and are threadedly connected to the valve body 1. Nuts 7-2 are threadedly fitted onto bolts 7-1 and are located above the valve cover 6. The double-layered self-locking washers 7-3 are pressed between nuts 7-2 and valve cover 6.

[0020] With this design, the marine gate valve of this application has a compact overall structure, suitable for stable operation in ship piping systems under frequent start-stop and vibration environments, and can significantly improve safety and durability. In particular, in this marine gate valve, the cooperation of double-layered self-locking gaskets 7-3 with bolts 7-1 and nuts 7-2 can achieve multiple anti-loosening measures, effectively improving the stability and sealing reliability of the valve body 1 connection. In actual use of this marine gate valve, the guide sleeve 3 can provide precise guidance for the lower valve stem 4-2, while the valve disc 2 is driven by the valve stem in the main channel to achieve axial opening and closing, resulting in stable overall performance. After setting annular sealing structures 3-1 inside and outside the guide sleeve 3, it can ensure that the medium has good anti-leakage performance under high pressure conditions. In addition, the valve stem adopts a multi-section split structure, which is convenient for assembly and maintenance.

[0021] Furthermore, such as Figure 1 As shown, in some embodiments, the upper valve stem 4-1 includes a pull rod section 4-1a and a push rod section 4-1b. The lower end of the pull rod section 4-1a is connected to the upper end of the lower valve stem 4-2. The outer circumferential surface of the pull rod section 4-1a is slidably fitted to the inner circumferential wall of the valve cover 6. The lower end of the push rod section 4-1b is detachably connected to the upper end of the pull rod section 4-1a. The upper end of the push rod section 4-1b passes through the valve cover 6 and is connected to the handwheel 5. Preferably, the lower end of the pull rod section 4-1a is provided with a T-slot, and the upper end of the lower valve stem 4-2 has a matching rectangular boss. The two are connected by sliding engagement. Under this design, the detachable connection structure of the push rod section 4-1b and the pull rod section 4-1a is beneficial to the assembly and maintenance of the marine gate valve.

[0022] Furthermore, in some embodiments, an upper anti-friction pad 8 is provided on the outer sleeve of the push rod section 4-1b, and the upper anti-friction pad 8 is located between the valve cover 6 and the handwheel 5. Even further, one end of the push rod section 4-1b located inside the valve cover 6 has a flange protruding from its outer periphery, and a lower anti-friction pad 9 is sandwiched between the flange and the inner wall of the valve cover 6. With this design, the upper anti-friction pad 8 and the lower anti-friction pad 9 can effectively reduce the frictional resistance when the valve rod rotates, improve the ease of operation, and at the same time reduce wear and extend service life.

[0023] Furthermore, such as Figure 3 As shown, in some embodiments, the lower valve stem 4-2 is threadedly connected to the valve disc 2. Furthermore, the marine shut-off valve also includes a locking element 10, which locks the lower valve stem 4-2 and valve disc 2 securely together. The locking element 10 may include, but is not limited to, screws. In this design, the valve disc 2 and the lower valve stem 4-2 are not only threadedly connected but also securely connected by the locking element 10, providing double fixation and effectively preventing loosening under vibration conditions, thus ensuring the reliability of the connection between the valve disc 2 and the valve stem.

[0024] Furthermore, such as Figure 1As shown, in some embodiments, both the inner and outer circumferential surfaces of the guide sleeve 3 are provided with annular grooves. The annular sealing structure 3-1 includes an O-ring and a retaining ring, with the inner sides of both the O-ring and the retaining ring embedded in the annular groove. In marine gate valves, the guide sleeve 3 and the valve stem are dynamically sealed by the annular sealing structure 3-1, while the guide sleeve 3 and the inner wall of the valve body 1 are statically sealed by another set of annular sealing structures 3-1, effectively preventing leakage of the medium along the main channel where the guide sleeve 3 is located. At the inner circumferential surface of the guide sleeve 3, the O-ring works in conjunction with the retaining ring to prevent extrusion failure under high pressure, thus improving the stability and durability of the sealing structure.

[0025] Furthermore, in some embodiments, four locking components 7 are distributed around the valve stem in a circumferential pattern to apply locking force evenly, ensuring that the valve stem is subjected to symmetrical force and operates smoothly during movement.

[0026] This application also discloses an assembly method for a marine gate valve, which includes the following steps: S1. Pre-process the components of the marine gate valve, including visual inspection, grinding and cleaning of the sealing surfaces.

[0027] Specifically, in some embodiments, the valve body 1, valve cover 6, valve stem, valve disc 2, and other components are first subjected to a visual inspection. This visual inspection includes: counting the number of parts before assembly, and cleaning all sharp edges and burrs with a file; particularly... Figures 4-7 The chamfers of the valve stem, valve body 1, valve cover 6 and other components shown (as circled in red) should be smooth and uniform. Measurement methods include, but are not limited to, visual inspection.

[0028] Then, to ensure a good seal, the sealing surfaces of the relevant components and the gaskets must be ground during assembly. Figure 8 (As shown in the image), and note that the grinding method should be concentric and in an arc direction, not in a straight line. The ground surface should be smooth and free of mirror-like tool marks. During grinding, first use coarse sandpaper for pre-grinding, and then use fine sandpaper or abrasive for fine grinding. After grinding, it is best to use a flashlight to illuminate and visually inspect the ground surface to ensure it is smooth and free of mirror-like tool marks. After completing the grinding of the sealing surface, clean each part with kerosene or other available cleaning fluid. After cleaning, blow off any kerosene adhering to each part with low-pressure air and wipe it clean with a clean cloth.

[0029] S2. Install annular sealing structure 3-1 on the outer and inner circumferential surfaces of guide sleeve 3, and then assemble valve disc 2, lower valve stem 4-2 and guide sleeve 3 and install them together into the main channel of valve body 1.

[0030] In this step, the guide sleeve 3 should be inspected and processed, specifically including: inspecting the chamfer of the annular groove of the guide sleeve 3 (such as...). Figure 9 As shown - Figure 11Check the smoothness of the area circled in red to determine if it facilitates O-ring installation and prevents scratches during installation. Also, process the guide sleeve 3, ensuring its inner and outer surfaces are clean and free of oil, particles, and other impurities. Special attention should be paid to keeping the sealing groove clean during this step. After inspection and processing, use tweezers to install the O-ring and retaining ring onto the guide sleeve 3, ensuring the O-ring is installed below the retaining ring. Then, evenly apply calcium-based grease to the O-ring groove of the guide sleeve 3.

[0031] Next, check if the valve stem end face is smooth to prevent scratching the O-ring. Also check if the molding material at the valve stem head is scratched. If the inspection fails, repair or replace the defective part to ensure that the end face is flat and free of burrs. After passing the inspection, thread the valve disc 2 to the valve stem and fix them together with screws. Then, install the assembled assembly in the main channel of the valve body 1.

[0032] S3. Connect the upper valve stem 4-1 to the lower valve stem 4-2, and fit the valve cover 6 onto the outer periphery of the upper valve stem 4-1.

[0033] In this step, first check that the surfaces of each part are free of burrs, deformation, and are clean, free of oil stains, particles, and other impurities, with particular emphasis on checking... Figure 12 The circled area is marked. If the inspection fails, the defective parts must be repaired or replaced. After passing the inspection, assemble according to the following steps: S31. Assemble the lower anti-friction washer 9 with the push rod section 4-1b in the upper valve stem 4-1, and apply grease to the threads of the push rod section 4-1b.

[0034] S32. Install the top rod section 4-1b with the lower anti-friction pad 9 along the axial direction of the valve cover 6 to the end of the valve cover 6, so that the upper anti-friction pad 8 fits against the inner top wall of the valve cover 6.

[0035] S33. Install the pull rod section 4-1a along the axis of the valve cover 6, so that the pull rod section 4-1a and the lower valve stem 4-2 are installed together by threaded connection.

[0036] S34. Reverse the lower valve stem 4-2 along the axis of the valve stem guide sleeve 3. Note that during installation, do not use excessive force to prevent damage to the O-ring.

[0037] S35. Assemble the upper valve stem 4-1, lower valve stem 4-2 and guide sleeve 3 (e.g., pass the lower valve stem 4-2 through the guide sleeve 3, and then assemble it by the rectangular boss at the upper end of the lower valve stem 4-2 and the T-shaped groove at the lower end of the pull rod section 4-1a). Then install it into the main channel of the valve body 1 along the axis of the main channel of the valve body 1. Then fit the valve cover 6 on the outer periphery of the upper valve stem 4-1, ensuring that the valve cover 6 is aligned with the threaded hole on the valve body 1.

[0038] S4. The valve cover 6 is connected to the valve body 1 using the locking assembly 7.

[0039] In this step, a torque wrench is preferably used to connect the valve cover 6 to the valve body 1 using bolt 7-1 (preferably a double-ended bolt 7-1), nut 7-2, and double-layered self-locking washers. The locking assembly 7 is preferably installed using a diagonal cross-tightening method. The installation steps are as follows: S41. Apply grease to the threads at both ends of bolt 7-1, and follow the instructions. Figure 13 Tighten bolt 7-1 in the threaded hole of valve body 1 in the order of position a → position b → position c → position d using a torque wrench; S42. According to Figure 13 Check the installation direction of the double-layer self-locking washers 7-3. Install the complete set of double-layer self-locking washers 7-3 with the correct orientation to positions a and b. Tighten the nuts 7-2 manually. During the process, pay attention to controlling the alignment of the washers and confirm visually. S43. Using the same method described above, install the double-layered self-locking washer 7-3 and nut 7-2 at positions c and d, as shown above. Figure 14 As shown; S44. Then, according to the final tightening torque (the torque is determined by the size of the double-ended bolt 7-1, the size of the nut 7-2, the material of the double-layer self-locking washer, and the material of the valve cover 6), use a torque wrench again to tighten each nut 7-2 in the order of position a→position b→position c→position d, one by one and symmetrically.

[0040] S45. Repeat the process twice more, using a torque wrench to apply the final tightening torque, and tighten each nut 7-2 in a symmetrical manner, following the order of position a → position b → position c → position d.

[0041] S46. Randomly remove a nut 7-2 and check if there are radial tooth marks on the valve cover 6; if radial tooth marks are present, the double-layer self-locking washer 7-3 is successfully installed, and the nut 7-2 and the double-layer self-locking washer 7-3 are reinstalled according to the above method; if no radial tooth marks are present, the double-layer self-locking washer 7-3 is installed unsuccessfully, and the double-layer self-locking washer 7-3 needs to be reinstalled according to the above process.

[0042] It is worth noting that after the tightness test is completed, the nuts 7-2 should be tightened one by one and symmetrically in the order of position a→position b→position c→position d, according to the final tightening torque, to ensure that the installation is in place.

[0043] S5. Connect handwheel 5 to upper valve stem 4-1 to assemble a marine shut-off valve.

[0044] In this step, first apply grease to the top thread of the upper valve stem 4-1; then install the handwheel 5 and the upper anti-friction washer 8 axially, and use a wrench to connect the handwheel 5 to the upper valve stem 4-1 with the hexagonal cap nut 7-2; at this point, the entire marine gate valve installation is complete. Figure 15 and Figure 16 As shown, during the installation process, the external interface of the valve body 1 needs to be equipped with a protective structure 11. The protective structure 11 includes, but is not limited to, the use of protective sleeves, protective films, etc. For example, the exposed threaded joints are fitted with plastic thread protective sleeves of the corresponding specifications, and the flange is fitted with a rubber protective sleeve (or steel protective cover); the handwheel 5 is wrapped with plastic film and then tied and fixed with polytetrafluoroethylene foam board.

[0045] It should be understood that expressions such as "comprising" and "may include" as used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as "comprising" and / or "having" may be interpreted as indicating a specific characteristic, number, operation, constituent element, component, or combination thereof, but should not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0046] It should be understood that the terms “center,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “inner,” “outer,” “clockwise,” “counterclockwise,” “axial,” “radial,” and “circumferential” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0047] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0048] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0049] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A marine gate valve, characterized in that, It includes a valve body (1), a valve disc (2), a guide sleeve (3), a valve stem, a handwheel (5), a valve cover (6), and a locking assembly (7), wherein: The valve body (1) has an axially penetrating main channel and a secondary channel that bypasses the main channel; the valve disc (2) is located in the main channel; the guide sleeve (3) is located at the upper port of the main channel and is positioned by the valve cover (6) and the valve body (1); the outer and inner circumferential surfaces of the guide sleeve (3) are provided with annular sealing structures (3-1); The valve stem includes an upper valve stem (4-1) and a lower valve stem (4-2). The lower valve stem (4-2) passes through the guide sleeve (3) and is connected to the valve disc (2). The lower end of the lower valve stem (4-2) is restricted in the main channel by the guide sleeve (3). The lower end of the upper valve stem (4-1) is connected to the lower valve stem (4-2), and its upper end passes through the valve cover (6) and is connected to the handwheel (5). By pulling the handwheel (5), the valve stem drives the valve disc (2) to move axially, which can adjust the opening and closing between the main channel and the secondary channel. The locking assembly (7) is distributed in multiple parts around the valve stem. The locking assembly (7) includes a bolt (7-1), a nut (7-2), and a double-layered self-locking washer (7-3). The bolt (7-1) passes through the valve cover (6) and is threadedly connected to the valve body (1). The nut (7-2) is threadedly fitted onto the bolt (7-1) and located above the valve cover (6). The double-layered self-locking washer (7-3) is pressed between the nut (7-2) and the valve cover (6).

2. The marine shut-off valve as described in claim 1, characterized in that, The upper valve stem (4-1) includes a pull rod section (4-1a) and a push rod section (4-1b). The lower end of the pull rod section (4-1a) is connected to the upper end of the lower valve stem (4-2). The outer circumferential surface of the pull rod section (4-1a) is slidably fitted to the inner circumferential wall of the valve cover (6). The lower end of the push rod section (4-1b) is detachably connected to the upper end of the pull rod section (4-1a). The upper end of the push rod section (4-1b) passes through the valve cover (6) and is connected to the handwheel (5).

3. The marine shut-off valve as described in claim 2, characterized in that, The top rod section (4-1b) is fitted with an upper anti-friction pad (8), which is located between the valve cover (6) and the handwheel (5).

4. The marine shut-off valve as described in claim 2, characterized in that, The top rod section (4-1b) has a flange protruding from the outer periphery of one end inside the valve cover (6), and a lower friction-reducing pad (9) is sandwiched between the flange and the inner wall of the valve cover (6).

5. The marine shut-off valve as described in claim 1, characterized in that, The lower valve stem (4-2) is threadedly connected to the valve disc (2).

6. The marine gate valve as described in claim 1, characterized in that, The marine shut-off valve also includes a locking element (10), and the lower valve stem (4-2) and the valve disc (2) are locked and fixed by the locking element (10).

7. The marine shut-off valve as described in any one of claims 1-6, characterized in that, The outer and inner circumferential surfaces of the guide sleeve (3) are provided with annular grooves, and the annular sealing structure (3-1) is embedded in the annular grooves.

8. A method for assembling a marine gate valve, characterized in that, Includes the following steps: S1. Pre-processing the components of the marine shut-off valve, the pre-processing including visual inspection, grinding of sealing surfaces and cleaning; S2. Install an annular sealing structure (3-1) on the outer and inner circumferential surfaces of the guide sleeve (3), and then assemble the valve disc (2), lower valve stem (4-2) and guide sleeve (3) together and install them into the main channel of the valve body (1); S3. Connect the upper valve stem (4-1) to the lower valve stem (4-2), and fit the valve cover (6) onto the outer periphery of the upper valve stem (4-1); S4. The valve cover (6) is connected to the valve body (1) using a locking assembly (7); S5. Connect the handwheel (5) to the upper valve stem (4-1) to assemble a marine shut-off valve.

9. The assembly method as described in claim 8, characterized in that, In step S4, the locking assembly (7) is installed using a diagonal cross-fastening method.

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