Marine ultralow-temperature stop valve with lock

Abstract

A marine ultra-low temperature stop valve with a lock is used for locking and opening a pipeline passage at ultra-low temperature and comprises a valve rod, a valve seat and a valve seat, the valve body is provided with a cavity, liquid can flow in the cavity, and the lower end of the valve rod is inserted into the cavity of the valve body; one end of the valve disc is connected with the lower end part of the valve rod, and the valve disc is positioned in the cavity of the valve body; the valve cover is arranged at the top of the valve body, and the lower end of the valve cover is fixedly connected with the upper end of the valve body through a fastener; the hand wheel is in threaded connection with the upper end part of the valve rod through a square tenon, and the rotatable hand wheel enables the valve rod to rotate and move up and down through rotation of the square tenon, so that opening and closing of the stop valve are realized; and the stop valve locking assembly can limit the up-and-down movement amplitude of the valve rod. The utility model can be applied to various complex piping systems, can be well used under the working condition of ultralow temperature of-163 DEG C of an LNG (Liquefied Natural Gas) ship, is provided with a locking device, can effectively avoid misoperation, and has extremely wide application.

Description

Technical Field

[0001] The utility model relates to the field of stop valves, in particular to a marine ultra-low temperature stop valve with a lock. Background Art

[0002] LNG carriers are special ships designed and built to transport liquefied natural gas at extremely low temperatures of -163°C. Among all current cargo ships, LNG carriers are the most technically complex and difficult to build, and are known as the "crown jewel" of world shipbuilding. Traditional valves cannot work under ultra-low temperature conditions, and may even deform or break due to material reasons. In addition, ordinary manual ultra-low temperature valves do not have locking devices, and once misoperation occurs, it is easy to cause liquefied natural gas leakage and damage to the pipeline system. The ultra-low temperature stop valve with lock for LNG ships was designed under this background. It can not only serve safely under -163°C conditions, but also avoid economic losses and safety risks caused by misoperation of shipboard personnel. Utility Model Content

[0003] The utility model aims to provide a marine ultra-low temperature stop valve with a lock, which has the advantages of being well used under ultra-low temperature working conditions of -163°C and being provided with a locking device to effectively avoid misoperation.

[0004] To achieve the above-mentioned purpose, the utility model provides a marine ultra-low temperature stop valve with a lock, which is used for locking and opening of pipeline passages under ultra-low temperature, comprising: a valve stem; a valve body, which is arranged as a cavity, wherein the cavity can be used for liquid to flow, and the lower end of the valve stem is inserted into the cavity of the valve body; a valve disc, one end of which is connected to the lower end of the valve stem and is located in the cavity of the valve body; a valve cover, which is arranged at the top of the valve body, and the lower end of the valve cover is fastened to the upper end of the valve body by a fastener; a handwheel, which is threadedly connected to the upper end of the valve stem by a square tenon, and the rotatable handwheel can be rotated by the square tenon to rotate the valve stem to rotate and move up and down, thereby realizing the opening and closing of the stop valve; a handwheel locking assembly and / or a switch locking device, wherein the handwheel locking assembly is arranged on the handwheel and can limit the rotation amplitude of the rotating handwheel; the switch locking device is arranged on the outside of the valve stem, moves simultaneously with the up and down movement of the valve stem, and can limit the movement amplitude of the valve stem.

[0005] Preferably, a valve seat is provided at the inner side wall of the valve body, and the inner diameter of the valve seat matches the outer diameter of the valve disc; when the valve stem moves downward, the valve disc is embedded in the valve seat and is in close contact with the inner side of the valve seat, so that the interior of the valve body is divided into two independent cavities, upper and lower, by the valve disc, and the stop valve is in a closed state; when the valve stem moves upward, the valve disc is disengaged from the state of close contact with the inner side of the valve seat, and the valve disc moves upward away from the valve seat, so that the aforementioned two independent cavities, upper and lower, are connected, and the stop valve is in an open state.

[0006] Preferably, the valve cover is a cavity structure, which includes an upper seat and a lower boss seat; the lower boss seat is fastened to the upper end of the valve body by fasteners to form a sealing surface; the outer edge of the lower boss seat protrudes radially outward to form an annular mounting surface; the upper seat is a cylindrical tubular structure with an internal cavity; the inner diameter of the upper seat matches the outer diameter of the valve stem, the valve stem is arranged in the upper seat, and the bottom end of the valve stem passes through the lower boss seat and then extends into the interior of the valve body.

[0007] Preferably, a metal composite gasket is further provided at the sealing surface; the metal composite gasket is a corrugated structure, and a flexible graphite or polytetrafluoroethylene material is bonded to its lower surface.

[0008] Preferably, a sealing positioning component is provided at the gap between the inner wall of the upper seat of the valve cover and the valve stem; the sealing positioning component includes: a stuffing pad, which is provided between the upper seat of the valve cover and the valve stem; a stuffing, which is provided on the stuffing pad; the stuffing pad and the stuffing are annular structures adapted to the valve stem, and the inner diameter of the annular structure matches the inner diameter of the valve stem.

[0009] Preferably, the packing is divided into an inner packing and an outer packing; the inner packing is the part in direct contact with the valve stem, and the inner packing adopts high-purity butterfly graphite; the outer packing is the part in contact with the inner wall of the upper pedestal, and the outer packing adopts nickel wire reinforced graphite.

[0010] Preferably, the sealing positioning component also includes: a packing sleeve, which is arranged at the upper end of the packing; a packing pressing cover, whose inner diameter matches the upper outer diameter of the valve cover, and is threadedly connected to the upper part of the valve cover and arranged at the upper end of the packing pressing cover, forming pressure downward and thereby pressing the packing pressing cover; the packing pressing cover is provided with an opening whose size matches the inner diameter of the valve stem for the valve stem to extend out; a plurality of O-ring grooves are sequentially arranged on the outer side of the packing pressing cover from top to bottom, and any of the O-ring grooves matches the outer diameter of the packing pressing cover; an O-ring is correspondingly arranged in any of the O-ring grooves.

[0011] Preferably, the handwheel locking assembly comprises: a cap nut and a handwheel gasket; the cap nut penetrates the handwheel gasket and is arranged on the upper plane of the handwheel to lock the top rotation height of the valve stem.

[0012] Preferably, the switch locking device comprises: an open-position locking portion and a closed-position locking portion integrally formed with the open-position locking portion; the closed-position locking portion is connected to the open-position locking portion and extends downwardly to be arranged below the packing pressing cover, and can be pressed against the bottom surface of the packing pressing cover when the stop valve is in the open state, thereby realizing a limiting function in the open state; the open-position locking portion is fixedly sleeved on the top end portion of the valve stem extending out of the valve cover, and the open-position locking portion can be pressed against the top surface of the packing pressing cover when the stop valve is in the closed state, thereby realizing a limiting function in the closed state.

[0013] Preferably, the switch locking device includes: a sliding groove, which is opened on the outside of the valve stem; a rotating nut, one end of which is arranged in the sliding groove, and the other end of the rotating nut is connected to the switch locking device. The switch locking device is arranged on the outside of the valve stem, and the switch locking device can be moved up and down in the sliding groove by rotating the rotating nut.

[0014] In summary, compared with the prior art, the marine cryogenic stop valve with lock provided by the utility model has the following beneficial effects:

[0015] First, the utility model can be applied to various complex piping systems and can be well used under the ultra-low temperature working condition of -163°C of LNG carriers.

[0016] Second, the utility model is provided with a locking device which can effectively avoid misoperation and has extremely wide applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of the utility model.

[0018] Figure markings: 1-valve body, 2-valve disc, 3-valve cover, 4-valve stem, 5-packing pad, 6-packing sleeve, 7-packing clamping cover, 8-handwheel, 9-threaded sleeve, 10-metal composite gasket, 11-packing, 12-inlet, 13-square tenon, 14-valve seat, 15-bolt gasket, 16-bolt, 17-first O-ring, 18-second O-ring, 19-handwheel gasket, 20-cap nut, 21-closed position locking part, 22-open position locking part, 23-third O-ring. DETAILED DESCRIPTION

[0019] The following will be combined with the appended examples in the present utility model Figure 1 , the technical scheme, structural features, objectives achieved and effects in the embodiments of the utility model are described in detail.

[0020] It should be noted that the drawings are in a very simplified form and use non-precise proportions. They are only used to conveniently and clearly assist in explaining the implementation methods of the utility model, and are not used to limit the conditions for the implementation of the utility model. Therefore, they have no substantive technical significance. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed by the utility model without affecting the efficacy and purpose that can be achieved by the utility model.

[0021] It should be noted that, in the present invention, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only the elements explicitly listed, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0022] like Figure 1 As shown, a marine cryogenic stop valve with a lock is used to lock and open pipeline passages under ultra-low temperatures, wherein ultra-low temperatures refer to external environments of -163°C and below. The stop valve includes:

[0023] The valve stem 4 is an important part of the stop valve, and is used to realize the switch of the stop valve, that is, the stop valve has an open state and a closed state, which will be described in detail later;

[0024] The valve body 1 is configured as a cavity, and the cavity can allow liquid to flow, such as liquid natural gas, etc.; the lower end of the valve stem 4 is inserted into the cavity of the valve body 1 through the inlet 12 of the valve body 1;

[0025] A valve disc 2, one end of which is fixedly connected to the lower end of the valve stem 4, and is located in the cavity of the valve body 1;

[0026] The hand wheel 8 is threadedly connected to the upper end of the valve stem 4 through the square tenon 13. The hand wheel 8 can be rotated to rotate the square tenon 13 to drive the force transmission control valve stem 4 to rotate up and down in the square tenon 13, thereby realizing the opening and closing of the stop valve. Among them, the square tenon 13 is a component for transmitting force; in specific operation, the hand wheel 8 is rotated to form a horizontal rotation force, and the square tenon 13 can convert the horizontal rotation force on the hand wheel 8 into a rotation force of the square tenon 13, because the square tenon 13 is threadedly connected to the valve stem 4, thereby driving the valve stem 4 to rotate up and down in the square tenon 13 and along the axial direction of the square tenon 13 to realize the opening and closing of the stop valve.

[0027] In order to enable the valve stem 4 to rotate and move up and down more smoothly and stably under the action of the handwheel 8 and the square tenon 13, the stop valve also includes: a threaded sleeve 9, which is fixedly arranged inside the lower boss seat of the valve cover 3. The threaded sleeve 9 is an annular structure adapted to the valve stem 4. The bottom end of the valve stem 4 passes through the threaded sleeve 9 and is inserted into the cavity of the valve body 1. The operator can better locate the axis of the valve stem 4 through the threaded sleeve 9. When the valve stem 4 rotates up and down, the valve stem 4 will also rotate in the threaded sleeve 9, which can effectively prevent the position of the valve disc 2 from shifting during the process of switching the stop valve.

[0028] In this embodiment, an annular square tenon 13 is adopted, which is matched with the inner diameter of the valve stem 4. The inside of the tenon 13 is threadedly connected to the valve stem 4, and the outside is fixedly connected to the handwheel 8. When the handwheel 8 rotates, the rotation causes the tenon 13 to rotate. Since the tenon 13 is threadedly connected to the valve stem 4, the valve stem 4 is driven to rotate and move up and down.

[0029] Furthermore, the globe valve further includes a valve cover 3, which is arranged at the top of the valve body 1. The lower end of the valve cover 3 is tightly connected to the upper end of the valve body 1 through fasteners. At this time, the lower surface of the valve cover 3 and the upper surface of the valve body 1 are closely attached to form a sealing surface, so as to ensure the sealing and stability of the liquid flow.

[0030] In addition, a valve seat 14 is arranged inside the valve body 1, and the inner diameter of the valve seat 14 is matched with the outer diameter of the valve disc 2. As described above, when the operator drives the valve stem 4 to move up and down by operating the handwheel 8, the valve disc 2 will also move up and down accordingly. When the valve disc 2 moves downward and is embedded in the valve seat 14 and is in close contact with the inner side of the valve seat 14, the inside of the valve body 1 is divided into two independent cavities, the upper and the lower, by the valve disc 2. At this time, the globe valve is in the closed state.

[0031] Similarly, when the valve disc 2 moves upward and separates from and leaves the valve seat 14 in the state of being in close contact with the inner side of the valve seat 14, at this time, the above-mentioned two independent cavities communicate with each other, and the globe valve is in the open state. Therefore, the opening and closing states of the globe valve can be switched by driving the valve disc 2 to move up and down by the valve stem 4.

[0032] Furthermore, the valve cover 3 has a cavity structure. As Figure 1 shown, it includes an upper pedestal and a lower boss pedestal. The lower boss pedestal is tightly connected to the upper end of the valve body 1 through fasteners to form a sealing surface. The outer edge of the lower boss pedestal protrudes radially outward to form an annular mounting surface, and the inner diameter of the lower boss pedestal is matched with the inner diameter of the inlet 12 of the valve body 1. The upper pedestal is in a cylindrical tubular structure and has an internal cavity. The inner diameter of the upper pedestal is matched with the outer diameter of the valve stem 4. The valve stem 4 is arranged inside the upper pedestal, and the bottom end of the valve stem 4 penetrates through the lower boss pedestal and extends into the inside of the valve body 1. In addition, in order to ensure the connection between the valve stem 4 and the handwheel 8, therefore, the top end of the valve stem 4 needs to extend out of the upper end of the valve cover 3. According to the above description, the cross-section of the valve cover 3 in the vertical direction is in the shape of "丄".

[0033] Furthermore, in order to make the sealing surface formed by the lower boss seat of the valve cover 3 and the upper end of the valve body 1 more solid, a metal composite gasket 10 is also provided at the sealing surface (i.e., between the lower boss seat and the valve body 1). The metal composite gasket 10 is a corrugated structure, and its lower surface is bonded with non-asbestos non-metallic materials such as flexible graphite or polytetrafluoroethylene. In a preferred embodiment, the corrugated structure of the metal composite gasket 10 is a wave tooth shape, which has better rebound compensation performance and lower preload. In this case, the fasteners fix the lower boss seat of the valve cover 3, the metal composite gasket 10 and the upper end of the valve body 1 in this order from top to bottom.

[0034] As mentioned above, the purpose of the fasteners here is to fix the valve cover 3, the metal composite gasket 10 and the valve body 1 together. In this embodiment, the fasteners are a combination of bolts 16 and bolt washers 15. The bolt washers 15 here can effectively prevent wear and increase the service life. The bolts 16 are fixedly connected in the order of the bolt washers 15, the annular mounting surface of the lower boss seat, the metal composite gasket 10, and the upper end of the valve body 1 from top to bottom.

[0035] In a preferred embodiment, in order to prevent the handwheel 8 from being misplaced or flying out due to excessive rotation amplitude when rotating, the stop valve is further provided with a cap nut 20 and a handwheel gasket 19. The cap nut 20 penetrates the handwheel gasket 19 and is arranged on the upper plane of the handwheel 8 to block the top rotation height of the valve stem 4, thereby limiting the number of rotations of the handwheel 8, and preventing the handwheel 8 from falling out due to excessive force when rotating the handwheel 8. The handwheel gasket 19 here can effectively prevent wear and increase the service life.

[0036] In this embodiment, the cap nut 20 is an annular structure, which is arranged on the upper plane of the handwheel 8 and has a cylindrical cavity inside for the top of the valve stem 4 to move up and down. In specific applications, the moving range of the valve stem 4 can be predetermined by controlling the height of the cylindrical cavity of the cap nut 20, thereby achieving the control of the number of rotations of the handwheel 8.

[0037] Furthermore, there is a certain gap between the top inner wall of the upper pedestal of the valve cover 3 and the valve stem 4, so a sealing positioning component can be provided to fully ensure the sealing performance of the valve.

[0038] The sealing positioning component includes a packing pad 5, which is arranged between the top end of the upper seat of the valve cover 3 and the valve stem 4. A packing 11 is placed on the packing pad 5. Because the stop valve is used under low temperature conditions, the packing 11 here should have the characteristic of achieving efficient sealing under low temperature conditions to fully ensure the sealing performance; here, the packing pad 5 and the packing 11 are annular structures adapted to the valve stem 4, and the inner diameters of the annular structures of the two should match the inner diameter of the valve stem 4 to achieve good sealing.

[0039] In a preferred embodiment, the packing 11 is divided into an inner layer and an outer layer. The inner layer is the part that is in direct contact with the valve stem 4 and is made of high-purity butterfly graphite; the outer layer is the part that is in contact with the inner wall of the upper pedestal and is made of nickel wire reinforced graphite, which has excellent scratch resistance and scraping and cleaning functions.

[0040] In order to further enhance the sealing performance of the sealing positioning component, the sealing positioning component also includes: a packing sleeve 6, which is arranged at the upper end of the packing 11; a packing pressing cover 7, whose inner diameter matches the outer diameter of the top end of the upper seat of the valve cover 3, is connected to the top end of the upper seat of the valve cover 3 by threads and is arranged at the upper end of the packing sleeve 6, forming downward pressure and then pressing the packing sleeve 6, so that the packing 11 is always in a compressed state, avoiding the leakage problem caused by the looseness of the packing 11 due to long-term use and temperature influence, and fully ensuring that the packing 11 is always in a compressed state to ensure the sealing performance. It should also be noted here that an opening with a size that matches the inner diameter of the valve stem 4 needs to be opened on the packing pressing cover 7 for the valve stem 4 to extend; in addition, the shape of the packing pressing cover 7 can be designed as needed. In this embodiment, the packing pressing cover 7 is an annular columnar structure with a circular cross section.

[0041] In addition, three O-ring grooves may be sequentially opened from top to bottom on the outer side of the packing gland 6, and any of the O-ring grooves matches the outer diameter of the packing gland 6. The first O-ring 17, the second O-ring 18, and the third O-ring 23 are sequentially placed in the three O-ring grooves from top to bottom to achieve sealing between the packing gland 6 and the inner wall of the upper seat of the valve cover 3, so as to further ensure its sealing performance and avoid valve leakage.

[0042] In order to enhance the stability of the valve stem 4 in the up and down movement and prevent dangerous situations such as deviation, the stop valve also includes: a switch locking device fixedly arranged on the outside of the valve stem 4, which moves simultaneously with the up and down movement of the valve stem 4, including: an open position locking portion 22 and a closed position locking portion 21 integrally formed with the open position locking portion 22, so that the open position locking portion 22 and the closed position locking portion 21 remain relatively stationary. Among them, the open position locking portion 22 is fixedly sleeved on the top end portion of the valve stem 4 extending out of the valve cover 3, and can be pressed against the top surface of the packing pressing cover 7 when the stop valve is in the closed state, so as to realize the limiting function in the closed state. The closed position locking portion 21 is connected to the open position locking portion 22 and extends downward to be arranged below the packing pressing cover 7, and can be pressed against the bottom surface of the packing pressing cover 7 when the stop valve is in the open state, so as to realize the limiting function in the open state.

[0043] In addition, in order to adapt to the limiting range in various situations, the stop valve also includes: a sliding groove, which is opened on the outside of the valve stem; one end of the rotating nut is arranged in the sliding groove, and the other end of the rotating nut is connected to the switch locking device. The switch locking device is arranged on the outside of the valve stem, and the switch locking device can be moved up and down in the sliding groove by rotating the rotating nut to achieve fixed-point limiting, thereby expanding the use range of the stop valve.

[0044] The utility model adopts multiple measures to fully guarantee the sealing performance of the valve. The valve cover 3 is designed strictly in accordance with the valve standard requirements to ensure the sealing performance during use; the stability of the open and closed states is achieved through multiple means to avoid the possibility of misoperation. All the above designs fully guarantee that the locked marine cryogenic stop valve has superior performance under the extremely low temperature operating conditions of liquefied natural gas ships.

[0045] Although the content of the utility model has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the utility model. After reading the above content, various modifications and substitutions of the utility model will be obvious to those skilled in the art. Therefore, the protection scope of the utility model should be limited by the attached claims.

Claims

1. A marine cryogenic stop valve with lock, used for locking and opening pipeline passages at ultra-low temperatures, characterized in that: include: Valve stem (4); The valve body (1) is arranged as a cavity, wherein the cavity can allow liquid to flow, and the lower end of the valve stem (4) is inserted into the cavity of the valve body (1); A valve disc (2), one end of which is connected to the lower end of the valve stem (4) and is located in the cavity of the valve body (1); A valve cover (3) is arranged on the top of the valve body (1), and the lower end of the valve cover (3) is fastened to the upper end of the valve body (1) via a fastener; The hand wheel (8) is threadedly connected to the upper end of the valve stem (4) through the square tenon (13), and the rotatable hand wheel (8) rotates through the square tenon (13) to make the valve stem (4) rotate and move up and down, thereby realizing the opening and closing of the stop valve; A handwheel locking assembly and / or a switch locking device, wherein the handwheel locking assembly is arranged on the handwheel (8) and can limit the rotation range of the rotating handwheel (8); the switch locking device is arranged on the outer side of the valve stem (4) and moves simultaneously with the up and down movement of the valve stem (4), and can limit the movement range of the valve stem (4).

2. A locked marine cryogenic stop valve according to claim 1, characterized in that: A valve seat (14) is provided on the inner side wall of the valve body (1), and the inner diameter of the valve seat (14) matches the outer diameter of the valve disc (2); When the valve stem (4) moves downward, the valve disc (2) is embedded in the valve seat (14) and is in close contact with the inner side of the valve seat (14), so that the interior of the valve body (1) is divided into two upper and lower independent cavities by the valve disc (2), and the stop valve is in a closed state; When the valve stem (4) moves upward, the valve disc (2) is separated from the state of close contact with the inner side of the valve seat (14), and the valve disc (2) moves upward to leave the valve seat (14), so that the two upper and lower independent cavities are connected and the stop valve is in an open state.

3. A locked marine cryogenic stop valve according to claim 1, characterized in that: The valve cover (3) is a cavity structure, which comprises an upper pedestal and a lower boss seat; The lower boss seat is fastened to the upper end of the valve body (1) via a fastener to form a sealing surface; The outer edge of the lower boss seat protrudes radially outward to form an annular mounting surface; The upper seat is a cylindrical tubular structure with an internal cavity; the inner diameter of the upper seat matches the outer diameter of the valve stem (4); the valve stem (4) is arranged in the upper seat, and the bottom end of the valve stem (4) passes through the lower boss seat and then extends into the interior of the valve body (1).

4. A locked marine cryogenic stop valve according to claim 3, characterized in that: A metal composite gasket (10) is also provided at the sealing surface; The metal composite gasket (10) is a corrugated structure, and a flexible graphite or polytetrafluoroethylene material is bonded to its lower surface.

5. A locked marine cryogenic stop valve according to claim 3, characterized in that: A sealing positioning component is provided at the gap between the inner wall of the upper pedestal of the valve cover (3) and the valve stem (4); the sealing positioning component comprises: A packing pad (5) is arranged between the upper seat of the valve cover (3) and the valve stem (4); A filler (11) is arranged on the filler pad (5); The packing pad (5) and the packing (11) are annular structures adapted to the valve stem (4), and the inner diameter of the annular structure matches the inner diameter of the valve stem (4).

6. A locked marine cryogenic stop valve according to claim 5, characterized in that: The filler (11) is divided into an inner layer filler and an outer layer filler; The inner filler is the part that is in direct contact with the valve stem (4), and the inner filler is made of high-purity butterfly graphite; The outer filler is the part in contact with the inner wall of the upper pedestal, and the outer filler is made of nickel wire reinforced graphite.

7. A locked marine cryogenic stop valve according to claim 6, characterized in that: The sealing positioning component also includes: A packing gland (6) is arranged at the upper end of the packing (11); A packing compression cover (7) whose inner diameter matches the outer diameter of the upper portion of the valve cover (3) and is threadedly connected to the upper portion of the valve cover (3) and arranged on the upper end of the packing compression sleeve (6) to form downward pressure and thereby compress the packing compression sleeve (6); The packing pressing cover (7) is provided with an opening whose size matches the inner diameter of the valve stem (4) so ​​as to allow the valve stem (4) to extend out; A plurality of O-ring grooves are sequentially arranged on the outer side of the packing gland (6) from top to bottom, and any of the O-ring grooves matches the outer diameter of the packing gland (6); An O-ring is correspondingly arranged in any of the O-ring grooves.

8. A locked marine cryogenic stop valve according to claim 1, characterized in that: The handwheel locking assembly comprises: A cap nut (20) and a handwheel gasket (19); the cap nut (20) penetrates the handwheel gasket (19) and is arranged on the upper plane of the handwheel (8) to position the top rotation height of the valve stem (4).

9. A locked marine cryogenic stop valve according to claim 6, characterized in that: The switch locking device comprises: An open-position locking portion (22) and a closed-position locking portion (21) integrally formed with the open-position locking portion (22); The closed-position locking portion (21) is connected to the open-position locking portion (22) and extends downward to be arranged below the packing pressing cover (7), and can be pressed against the bottom surface of the packing pressing cover (7) when the stop valve is in the open state, thereby realizing a limiting function in the open state; The open position locking portion (22) is fixedly sleeved on the top end portion of the valve stem (4) extending out of the valve cover (3). The open position locking portion (22) can be pressed against the top surface of the packing pressing cover (7) when the stop valve is in the closed state, thereby realizing a limiting function in the closed state.

10. A locked marine cryogenic stop valve according to claim 9, characterized in that: The switch locking device comprises: A sliding groove is formed on the outer side of the valve stem (4); A rotating nut, one end of which is arranged in the sliding groove, and the other end of which is connected to the switch locking device. The switch locking device is arranged on the outside of the valve stem (4), and the switch locking device can be moved up and down in the sliding groove by rotating the rotating nut.

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