Large bore marine suction check valve and method of installation and use

Abstract

The application discloses a large-diameter suction check valve for ships, which comprises a valve body, a guide rod, an upper supporting plate and a sealing gasket; the valve body is hollow, and is formed by butt joint and fixation of an upper valve body and a lower valve body; the lower end of the lower valve body is the inlet of the whole valve body, the inside of the lower valve body is upwardly protruded to form a valve port sealing seat, and the middle part of the valve port sealing seat is formed with a valve port for medium circulation; the upper supporting plate and the sealing gasket are fixed to form a valve clack after being overlapped, the valve clack is connected to the lower end of the guide rod and reciprocates up and down along with the guide rod; and the contact surface between the valve port sealing seat and the sealing gasket is arranged in an arc shape. The application further discloses a mounting and using method of the large-diameter suction check valve for ships. The application has the beneficial effects that the contact surface between the valve port sealing seat and the sealing gasket is arranged in a circular arc shape, so that the accumulation of impurities on the sealing surface is reduced, the valve clack cannot be completely closed due to the blockage of impurities is avoided, and the problems of poor sealing effect and easy leakage of the existing large-diameter check valve for ships are effectively solved.

Description

Technical Field

[0001] This invention relates to the field of pipeline fluid control technology, specifically to a large-diameter marine suction check valve and its installation and usage method. Background Technology

[0002] Marine suction check valves mainly consist of a valve body, valve disc, spring, and sealing ring. Their working principle is based on the forward flow of the medium opening the valve disc; when the fluid flows in the reverse direction, the fluid pressure and the valve disc's own weight close the valve disc, thus preventing backflow. According to marine suction check valve standards, suction check valves are classified into four types: R, RS, Y, and YS, corresponding to different flange connection sizes and sealing methods. The R and RS types (suction check valves with a nominal size ≤ DN250 in CB / T3478-2025) have the following structure: Figure 1 As shown, the device includes a valve body (composed of an upper valve body and a lower valve body), a guide rod, an upper support plate, and a rubber sealing gasket. A communication port is formed in the middle of the valve body. The upper support plate and the disc-shaped rubber gasket are stacked vertically to form a valve disc, which is connected to the lower end of the guide rod and can move up and down with the guide rod to open or close the communication port. The disc-shaped rubber sealing gasket has a flat contact surface with the valve body. The upper and lower support plates hold the valve disc, with the lower support plate located at the center of the upper support plate and fixed by fastening bolts. Figure 2 As shown. The main reasons for the poor sealing effect of this type of marine check valve are as follows: 1. Wear or corrosion of the sealing surface: During long-term use, the sealing surface between the valve disc and the valve seat is worn, scratched or corroded due to frequent opening and closing, scouring by medium particles or corrosive fluids (such as seawater, acidic media); 2. Blockage by impurities: Impurities in the medium (such as mud, sand, scale) get stuck between the sealing surfaces, preventing the valve disc from closing completely.

[0003] The maximum nominal size of marine suction check valves according to relevant standards is DN250. As the size increases, the following two problems become more pronounced: 1. With the increase in nominal size, the contact length / area between the rubber gasket and the valve body is larger, increasing the probability of impurities in the medium (such as mud, scale, and iron filings) getting stuck between the sealing surfaces, leading to poor sealing performance. 2. The most common solution for poor sealing is to replace the rubber gasket. However, with the increase in nominal size, the size of the rubber gasket also increases, but the actual effective usable area is only the edge in contact with the valve body. Furthermore, the increased size makes the rubber gasket's fixation worse, more expensive, and more difficult to replace. In actual use, traditional large-diameter suction check valves have poor sealing performance. After the system stops suction, the liquid medium in the pipeline leaks out quickly due to gravity backflow, and even replacing the rubber gasket cannot guarantee a long-term sealing effect. This solution addresses these two significant problems by improving the large-diameter marine suction check valve. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a large-diameter marine suction check valve and its installation and usage method, aiming to solve the problem of poor sealing performance in existing technologies.

[0005] The technical solution adopted in this invention is as follows: a large-diameter marine suction check valve, comprising a valve body, a guide rod, an upper support plate, and a sealing gasket; the valve body is hollow inside and is formed by connecting and fixing an upper valve body and a lower valve body; the lower port of the lower valve body is the inlet of the entire valve body, and the interior of the lower valve body protrudes upward to form a valve port sealing seat, the middle of which forms a valve port for medium flow; the upper support plate and the sealing gasket are stacked and fixed to form a valve flap, which is connected to the lower end of the guide rod and can move up and down with the guide rod; when the lower surface of the sealing gasket is in contact with the valve port sealing seat of the lower valve body, the valve port is closed; when the sealing gasket and the valve port sealing seat are separated, the valve port is opened; the mating contact surface between the valve port sealing seat and the sealing gasket is set as an arc-shaped contact surface.

[0006] According to the above scheme, it also includes a lower support plate; both the sealing gasket and the lower support plate adopt a circular structure, and the two are arranged coaxially with the upper support plate; the lower surface of the upper support plate bulges downward to form a boss structure, and the lower support plate is fixedly installed at the bottom of the boss structure; the outer wall of the boss structure, the lower surface of the upper support plate, and the upper surface of the lower support plate together form a ring mounting part, and the inner circumferential part of the sealing gasket is embedded and fixed in the ring mounting part.

[0007] According to the above scheme, the lower end of the guide rod passes through the center of the upper support plate, and the upper support plate is axially limited by a limiting plate.

[0008] According to the above scheme, the bottom of the upper support plate is axially limited by a slotted nut that is threaded with the guide rod.

[0009] According to the above scheme, the center of the upper support plate extends downward to form a thickened middle part, and the guide rod passes through the thickened middle part.

[0010] According to the above scheme, a valve cover is provided inside the upper valve body, and the valve cover is fixedly connected to the inner wall of the upper valve body through a transverse connecting piece; a guide hole adapted to the guide rod is opened in the center of the valve cover, and the upper end of the guide rod passes through the guide hole and moves up and down along the guide hole.

[0011] According to the above scheme, a return spring is sleeved on the guide rod, the upper end of the return spring is in contact with the lower surface of the valve cover, and the lower end of the return spring is in contact with the upper support plate.

[0012] According to the above scheme, a filter screen is fitted on the outer side of the lower port of the lower valve body.

[0013] This invention also employs an installation method for a large-diameter marine suction check valve as described above, the method being: First, fasten the lower support plate to the bottom of the boss structure of the upper support plate, so that the sealing gasket is clamped and positioned in the annular mounting part, and the valve disc is assembled as a whole. Next, insert the guide rod from top to bottom into the thickened middle part of the upper support plate, and lock the bottom of the guide rod to complete the assembly of the valve disc and the guide rod; Next, install the return spring on the upper part of the guide rod, and insert the upper part of the guide rod into the guide hole in the center of the valve cover to achieve axial limiting of the guide rod; Finally, connect and secure the upper valve body to the lower valve body.

[0014] This invention also employs a method for using the large-diameter marine suction check valve as described above, the method being: In the medium suction operation, when the pipeline is performing liquid medium suction operation, the medium pressure acts on the lower end face of the valve disc, overcoming the valve disc's own weight and the preload of the return spring, pushing the valve disc to move upward along the guide rod, causing the sealing gasket to separate from the valve port sealing seat, the valve port to open, and the medium to pass smoothly through the valve port and the flow channel between the valve disc and the valve body, thus achieving normal suction and delivery. When the pipeline stops drawing in medium and the medium pressure disappears, the valve disc returns downward under its own weight and the force of the return spring. The sealing gasket is pressed tightly against the valve port sealing seat again, the valve port is closed and a seal is formed, preventing the medium in the pipeline from flowing back and realizing the check function. When repairing or replacing the gasket, first disassemble the upper and lower valve bodies and remove the valve disc; loosen the fastening bolts on the lower support plate, remove the double-eared stop washer and the lower support plate, and remove the worn or failed gasket from the annular mounting part; replace the gasket with a new one and insert it into the annular mounting part, reset the lower support plate, reinstall the double-eared stop washer and tighten the fastening bolts to complete the gasket replacement; finally, reinstall the valve disc assembly into the valve body, and close the upper and lower valve bodies to restore its use.

[0015] The beneficial effects of this invention are: 1. This invention sets the mating surface of the valve seat and the gasket to an arc shape, which can reduce the accumulation of impurities on the sealing surface and prevent the valve disc from failing to close completely due to impurities. This effectively solves the problems of poor sealing effect and easy leakage in existing large-diameter marine check valves, and improves sealing reliability and check performance. Furthermore, by improving sealing reliability and reducing leakage on the sealing surface, it can effectively delay the backflow and loss of liquid medium in the pipeline, thereby extending the retention time of liquid medium in the pipeline section after the check valve. This ensures that the pipeline remains full of liquid after shutdown, ensuring that pumps can operate smoothly when the system is restarted next time. It also avoids abnormal operation caused by air entering the pipeline and eliminates the need for refilling and venting.

[0016] 2. This invention adjusts the structure of the rubber gasket, lower support plate, and upper support plate, adopting a ring-shaped fixed installation method. This enhances the stability of the rubber gasket while reducing the amount of material used, facilitating the fixing and replacement of the gasket. Furthermore, the annular mounting part ensures reliable embedding and positioning of the gasket, preventing it from shifting or falling off under media impact and vibration conditions, thus guaranteeing sealing accuracy. This further solves the problem of poor sealing performance in existing technologies. Combined with the arc-shaped sealing surface structure, it comprehensively improves the valve's sealing reliability and economic efficiency. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of an existing intake check valve.

[0018] Figure 2 This is a schematic diagram showing the connection between the valve disc and the lower valve body of an existing intake check valve.

[0019] Figure 3 This is a schematic diagram of the overall structure of Example 1.

[0020] Figure 4 This is a schematic diagram showing the connection between the lower valve body and the valve disc in this embodiment.

[0021] Figure 5 This is a schematic diagram of the contact surface between the lower valve body and the sealing gasket in this embodiment.

[0022] The components include: 1. Upper valve body; 2. Guide rod; 3. Upper support plate; 4. Sealing gasket; 5. Lower valve body; 6. Filter screen; 7. Lower support plate; 8. Slotted nut; 9. Double-eared stop washer; 10. Fastening bolt; 11. Thickened middle part; 12. Boss structure; 13. Limiting plate; 14. Return spring; 15. Valve cover; 16. Transverse connecting piece. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of 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 the description of the embodiments of this application, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of 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 the embodiments of this application. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0025] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" 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. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0026] In the embodiments of this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0027] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the embodiments of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples, without contradiction. Additionally, the term "a plurality of" indicates two or more.

[0028] Example 1 like Figure 3 The large-diameter marine suction check valve shown refers specifically to a marine suction check valve with a nominal size of not less than DN250. Specifically, the large-diameter marine suction check valve includes a valve body, a guide rod 2, an upper support plate 3, and a sealing gasket 4. The valve body is hollow inside and is formed by connecting and fixing an upper valve body 1 and a lower valve body 5. The lower port of the lower valve body 5 is the inlet of the entire valve body, and the interior of the lower valve body 5 protrudes upward to form a valve port sealing seat. The valve port sealing seat forms a valve port for medium flow in the middle. The upper support plate 3 and the sealing gasket 4 are stacked and fixed to form a valve disc, which is connected to the lower end of the guide rod 2 and can move up and down with the guide rod 2. When the lower surface of the valve disc, i.e., the lower surface of the sealing gasket 4, is in contact with the valve port sealing seat of the lower valve body 5, the valve port is closed; when the sealing gasket 4 separates from the valve port sealing seat, the valve port opens. The mating contact surface between the valve port sealing seat and the sealing gasket 4 is set as an arc-shaped contact surface, such as... Figure 5 As shown.

[0029] In this invention, the mating contact surface between the valve port sealing seat and the sealing gasket 4 is designed as an arc-shaped structure. Compared with the traditional planar contact, this significantly reduces the dead angle of impurity accumulation in the sealing mating area. When solid impurities such as mud, scale, and iron filings are carried in the medium and flow through the sealing part, the arc-shaped contact surface can guide and avoid the impurities, making them less likely to be trapped or stuck in the sealing mating gap. This effectively reduces the risk of impurities embedding or being stuck between the sealing surfaces, and structurally avoids the problem of the valve disc not being able to fully sit and close due to impurities. This ensures that the sealing gasket 4 and the valve port sealing seat can always fit tightly, improving the sealing effect.

[0030] Preferably, such as Figure 4As shown, both the sealing gasket 4 and the lower support plate 7 adopt an annular structure, and they are coaxially arranged with the upper support plate 3; the lower surface of the upper support plate 3 protrudes downward to form a boss structure 12, and the lower support plate 7 is fixedly installed at the bottom of the boss structure 12; the outer wall of the boss structure 12, the lower surface of the upper support plate 3, and the upper surface of the lower support plate 7 together form an annular mounting part, and the inner circumference of the sealing gasket 4 is embedded and fixed in the annular mounting part.

[0031] In this invention, the sealing gasket 4 is made of rubber material and is tightly fitted to the lower surface of the upper support plate 3 and the upper surface of the lower support plate 7, respectively, to achieve stable positioning and reliable support. The lower support plate 7 and the upper support plate 3 are fastened together by multiple fastening bolts 10 arranged at even intervals along the circumference, ensuring uniform connection strength and preventing the sealing gasket 4 from shifting or falling off during opening and closing. A double-eared retaining washer 9 is provided between the lower support plate 7 and the head of the fastening bolt 10. The double-eared retaining washer 9 can be used to circumferentially limit the fastening bolt 10, effectively preventing the fastening bolt 10 from loosening or disengaging under vibration and media impact conditions, ensuring a firm and reliable connection between the lower support plate 7 and the upper support plate 3, and improving the overall assembly stability of the sealing assembly.

[0032] In this invention, the boss structure 12, the upper support plate 3, the lower support plate 7, and the sealing gasket 4 are designed coaxially.

[0033] Preferably, the lower end of the guide rod 2 passes through the center of the upper support plate 3, the upper support plate 3 is axially limited by a limiting plate 13 fixed to the guide rod 2, and the bottom of the upper support plate 3 is axially limited by a slotted nut 8 that is threaded with the guide rod 2.

[0034] In this invention, the limiting plate 13 and the slotted nut 8 cooperate to form an upper and lower limiting structure, which can limit the axial position of the upper support plate 3, making the valve disc stable and controllable during opening and closing. At the same time, it can effectively prevent the upper support plate 3 from excessive movement, displacement or detachment under the conditions of medium pressure impact, water flow disturbance and ship vibration, ensuring smooth and reliable valve disc movement, and improving the consistency of valve opening and closing and sealing stability. The slotted nut 8 can achieve mechanical anti-loosening, preventing loosening and falling off under vibration conditions, ensuring the stable connection between the upper support plate 3 and the guide rod 2, and improving the overall working reliability of the valve.

[0035] Preferably, the mating part between the upper support plate 3 and the guide rod 2 is provided with a thickened structure; specifically, the center position of the upper support plate 3 extends downward to form a thickened middle part 11, and the guide rod 2 passes through the thickened middle part 11.

[0036] In this invention, by providing a thickened middle part 11 at the center of the upper support plate 3, the structural strength and rigidity of the mating area between the upper support plate 3 and the guide rod 2 can be improved, effectively resisting the impact of medium pressure and the alternating load during the opening and closing process, and preventing deformation, cracking or wear of the central part of the upper support plate 3 due to concentrated force; at the same time, the mating contact length between the upper support plate 3 and the guide rod 2 is increased, improving the coaxiality and motion stability of the two assembly, and preventing the upper support plate 3 from swaying or jamming during reciprocating motion.

[0037] Preferably, a valve cover 15 is provided inside the upper valve body 1, and the valve cover 15 is fixedly connected to the inner wall of the upper valve body 1 by a transverse connecting member 16 around its perimeter; a guide hole adapted to the guide rod 2 is opened in the center of the valve cover 15, the upper end of the guide rod 2 passes through the guide hole and can move up and down along the guide hole.

[0038] In this invention, the guide rod 2 is limited by a guide hole, and a sealing ring and a sleeve are provided in the guide hole to prevent liquid impurities from entering and affecting the movement of the guide rod 2.

[0039] In this invention, the transverse connecting member 16 can fix the valve cover 15 to the upper valve body 1. The transverse connecting member 16 is composed of multiple rods, and the hollow part between the rods forms a liquid flow channel. The guide rod 2 is slidably connected to the guide hole in the center of the valve cover 15, so that the guide rod 2 makes a stable reciprocating up and down movement during the operation of the valve, which improves the coaxiality and stability of the valve disc movement, prevents misalignment of the sealing fit, and ensures smooth opening and closing of the valve and reliable sealing.

[0040] Preferably, a return spring 14 is also sleeved on the guide rod 2, the upper end of the return spring 14 is in contact with the lower surface of the valve cover 15, and the lower end of the return spring 14 is in contact with the upper support plate 3.

[0041] In this invention, the return spring 14 is used to provide a downward return preload force for the valve disc. When the medium suction disappears or reverse pressure appears, or when the valve is not installed vertically and the valve disc cannot close by its own weight, the return spring 14 can push the valve disc to fall back onto the valve port sealing seat quickly and reliably and achieve closure, thereby enhancing the check response speed and improving the valve closing timeliness and sealing stability.

[0042] Preferably, a filter screen 6 is fitted onto the outer side of the lower port of the lower valve body 5.

[0043] In this invention, the filter screen 6 can initially filter and intercept larger impurities in the intake medium, preventing large debris from entering the valve cavity, reducing scratches and blockages on the sealing surface caused by impurities, protecting the sealing gasket 4 and the valve port sealing seat, and extending the service life of the valve.

[0044] Example 2 This embodiment discloses an installation method for the large-diameter marine suction check valve described in Embodiment 1, the method being as follows: First, insert a double-eared stop washer 9 between the lower support plate 7 and the head of the fastening bolt 10. Then, fasten the lower support plate 7 to the bottom of the boss structure 12 of the upper support plate 3 with the fastening bolts 10 arranged evenly around the circumference, so that the sealing gasket 4 is reliably clamped and positioned in the annular mounting part, and the valve disc is assembled as a whole. Next, the guide rod 2 is inserted from top to bottom into the thickened middle part 11 of the upper support plate 3. The bottom of the guide rod 2 is locked with a slotted nut 8 to complete the assembly of the valve disc and the guide rod 2. Next, install the return spring 14 on the upper part of the guide rod 2, and insert the upper part of the guide rod 2 into the guide hole in the center of the valve cover 15 to achieve axial limiting of the guide rod 2; Finally, connect and fix the upper valve body 1 and the lower valve body 5 together.

[0045] During installation, the boss structure 12, the upper support plate 3, the lower support plate 7 and the sealing gasket 4 should be arranged coaxially to ensure smooth valve disc movement and reliable sealing.

[0046] Example 3 This embodiment discloses a method for using the large-diameter marine suction check valve described in Embodiment 1. The method is as follows: When the pipeline is in the process of sucking up liquid medium, the medium pressure acts on the lower end face of the valve disc, which overcomes the weight of the valve disc itself and the preload of the return spring 14, and pushes the valve disc to move upward along the guide rod 2, so that the sealing gasket 4 separates from the valve port sealing seat, the valve port opens, and the medium passes smoothly through the valve port and the flow channel between the valve disc and the valve body, so as to achieve normal suction and delivery. When the suction and check valve conditions are stopped, when the pressure in the pipeline stops and the suction pressure disappears, the valve disc returns downward under its own weight and the force of the return spring 14. The sealing gasket 4 is pressed tightly against the valve port sealing seat again, the valve port is closed and a seal is formed, preventing the backflow of the medium in the pipeline, realizing the check valve function, and ensuring the system's sealing performance. When replacing the sealing gasket 4, first disassemble the upper valve body 1 and the lower valve body 5, and remove the valve disc; loosen the fastening bolts 10 on the lower support plate 7, remove the double-eared stop washer 9 and the lower support plate 7, and remove the worn or failed sealing gasket 4 from the annular mounting part; replace the new sealing gasket 4 and embed it into the annular mounting part, reset the lower support plate 7, reinstall the double-eared stop washer 9 and tighten the fastening bolts 10 to complete the replacement of the sealing gasket 4; finally, reinstall the valve disc assembly into the valve body, close the upper and lower valve bodies 5 to restore use, which is convenient to disassemble and assemble and has high maintenance efficiency.

[0047] The large-diameter marine suction check valve described in Example 1 has been put into actual production, and its sealing effect has been greatly improved compared with the prior art.

[0048] The large-diameter marine suction check valve described in Example 1 has been prototyped and tested. Comparative testing and actual shipboard operation verification with traditional marine suction check valves of the same specifications have shown that this invention, through dual improvements in the arc-shaped sealing surface structure and the annular sealing gasket assembly structure, enhances the valve's sealing performance and closing reliability. It effectively avoids sealing failures caused by impurities clogging or gasket displacement. The overall sealing performance, operational stability, and service life are superior to existing technologies, better meeting the needs of large-diameter marine piping systems.

[0049] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

[0050] Finally, it should be noted that the above are merely preferred embodiments of this application and are not intended to limit this application. Although this application has been described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. However, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A large-diameter marine suction check valve, characterized in that, The valve includes a valve body, a guide rod, an upper support plate, and a sealing gasket. The valve body is hollow and is formed by connecting and fixing an upper valve body and a lower valve body. The lower port of the lower valve body is the inlet of the entire valve body, and the interior of the lower valve body protrudes upward to form a valve port sealing seat. The valve port sealing seat forms a valve port for the flow of medium in the middle. The upper support plate and the sealing gasket are stacked and fixed to form a valve flap, which is connected to the lower end of the guide rod and moves up and down with the guide rod. When the lower surface of the sealing gasket is in contact with the valve port sealing seat of the lower valve body, the valve port is closed. When the sealing gasket and the valve port sealing seat are separated, the valve port is opened. The mating contact surface between the valve port sealing seat and the sealing gasket is set as an arc-shaped contact surface.

2. The large-diameter marine suction check valve as described in claim 1, characterized in that, It also includes a lower support plate; both the sealing gasket and the lower support plate adopt a circular structure, and they are arranged coaxially with the upper support plate; the lower surface of the upper support plate bulges downward to form a boss structure, and the lower support plate is fixedly installed at the bottom of the boss structure; the outer wall of the boss structure, the lower surface of the upper support plate, and the upper surface of the lower support plate together enclose to form a ring mounting part, and the inner circumferential part of the sealing gasket is embedded and fixed in the ring mounting part.

3. The large-diameter marine suction check valve as described in claim 2, characterized in that, The lower end of the guide rod passes through the center of the upper support plate, and the upper support plate is axially limited by a limiting plate fixed to the guide rod.

4. The large-diameter marine suction check valve as described in claim 3, characterized in that, The bottom of the upper support plate is axially limited by a slotted nut that mates with the guide rod thread.

5. The large-diameter marine suction check valve as described in claim 4, characterized in that, The upper support plate extends downward from its center to form a thickened middle section, and the guide rod passes through the thickened middle section.

6. The large-diameter marine suction check valve as described in claim 5, characterized in that, The upper valve body is provided with a valve cover inside, and the valve cover is fixedly connected to the inner wall of the upper valve body through a transverse connecting piece; the center of the valve cover is provided with a guide hole that matches the guide rod, the upper end of the guide rod passes through the guide hole and moves up and down along the guide hole.

7. The large-diameter marine suction check valve as described in claim 6, characterized in that, A return spring is fitted on the guide rod. The upper end of the return spring contacts the lower surface of the valve cover, and the lower end of the return spring contacts the upper support plate.

8. The large-diameter marine suction check valve as described in claim 7, characterized in that, A filter screen is fitted on the outer side of the lower port of the lower valve body.

9. A method for installing a large-diameter marine suction check valve as described in claim 7, characterized in that, The method is as follows: First, fasten the lower support plate to the bottom of the boss structure of the upper support plate, so that the sealing gasket is clamped and positioned in the annular mounting part, and the valve disc is assembled as a whole. Next, insert the guide rod from top to bottom into the thickened middle part of the upper support plate, and lock the bottom of the guide rod to complete the assembly of the valve disc and the guide rod; Next, install the return spring on the upper part of the guide rod, and insert the upper part of the guide rod into the guide hole in the center of the valve cover to achieve axial limiting of the guide rod; Finally, connect and secure the upper valve body to the lower valve body.

10. A method of using the large-diameter marine suction check valve as described in claim 8, characterized in that, The method is as follows: In the medium suction operation, when the pipeline is performing liquid medium suction operation, the medium pressure acts on the lower end face of the valve disc, overcoming the valve disc's own weight and the preload of the return spring, pushing the valve disc to move upward along the guide rod, causing the sealing gasket to separate from the valve port sealing seat, the valve port to open, and the medium to pass smoothly through the valve port and the flow channel between the valve disc and the valve body, thus achieving normal suction and delivery. When the pipeline stops drawing in medium and the medium pressure disappears, the valve disc returns downward under its own weight and the force of the return spring. The sealing gasket is pressed tightly against the valve port sealing seat again, the valve port is closed and a seal is formed, preventing the medium in the pipeline from flowing back and realizing the check function. When repairing or replacing the gasket, first disassemble the upper and lower valve bodies and remove the valve disc; loosen the fastening bolts on the lower support plate, remove the double-eared stop washer and the lower support plate, and remove the worn or failed gasket from the annular mounting part; replace the gasket with a new one and insert it into the annular mounting part, reset the lower support plate, reinstall the double-eared stop washer and tighten the fastening bolts to complete the gasket replacement; finally, reinstall the valve disc assembly into the valve body, and close the upper and lower valve bodies to restore its use.

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