A low-torque cryogenic ball valve

Abstract

This utility model relates to a low-torque cryogenic ball valve, comprising a valve stem, a thrust pad fitted at the upper part of the valve stem, a gland flange and a top flange fitted on the outside of the valve stem, the top flange being located above the gland flange and fixedly connected to the gland flange, and a plug ring, a packing gasket ring, packing, a pressure sleeve and a pressure plate arranged from bottom to top between the valve stem and the gland flange, the pressure plate being fixed to the gland flange. In existing cryogenic ball valves, the thrust pad is located at the end of the valve stem, and under long-term low-temperature conditions, the friction coefficient increases significantly, and the torque increases accordingly. In contrast, the thrust pad of this structure is located away from the low-temperature environment, in a normal temperature environment, thus effectively reducing the friction coefficient of the thrust pad and thereby reducing the torque.

Description

Technical Field

[0001] This utility model belongs to the field of ball valve technology, specifically relating to a low-torque cryogenic ball valve. Background Technology

[0002] In recent years, with the rise of the LNG industry, the application of cryogenic ball valves has become more and more widespread, intensifying industry competition and reducing gross profit. The torque of a cryogenic ball valve of the same specification is about three times that of a general ball valve. Therefore, the fundamental advantage of cryogenic ball valves lies in their high performance and low torque.

[0003] As is well known, the friction coefficient of the thrust pad at room temperature is much smaller than that at low temperature. In existing ball valves, the thrust pad is located at the end of the valve stem, close to the ball. Under operating conditions, it is in a low-temperature environment for a long time, which greatly increases the friction coefficient and the torque will increase accordingly. Therefore, how to design a low-torque cryogenic ball valve has become the key to market competition. Utility Model Content

[0004] The purpose of this invention is to provide a low-torque cryogenic ball valve, which adopts a thrust pad upward displacement structure, thereby greatly reducing the torque of the cryogenic ball valve.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a low-torque cryogenic ball valve, comprising a valve stem, a thrust pad fitted on the upper part of the valve stem, a gland flange and a top flange fitted on the outside of the valve stem, the top flange being located above the gland flange and fixedly connected to the gland flange, and a plug ring, a packing gasket, packing, a pressure sleeve and a pressure plate arranged from bottom to top between the valve stem and the gland flange, the pressure plate being fixed to the gland flange.

[0006] Furthermore, a dustproof groove is provided on the top flange, and a dustproof O-ring is embedded in the dustproof groove.

[0007] Furthermore, the gland flange and the top flange are fixedly connected by multiple glands and top flange screws.

[0008] Furthermore, the pressure plate and the gland flange are fixedly connected by multiple pressure plates and gland flange screws.

[0009] Furthermore, a disc spring is provided between the pressure plate and the flange screws of the pressure plate.

[0010] Furthermore, the mating surface between the pressure sleeve and the pressure plate is a tapered surface.

[0011] Compared with the prior art, this utility model has the following advantages:

[0012] 1. Existing cryogenic ball valves use top flange pre-tightened packing. During operation, the top flange gradually loosens due to the impact of actuator switching, which may lead to valve stem packing leakage. This structure, however, uses a pressure plate packing structure. The pressure plate and gland flange bolts, as well as the gland and top flange bolts, are all pre-tightened independently and do not affect each other. Thus, even if the top flange loosens during operation, it will not affect the valve stem packing seal, greatly reducing the risk of valve stem leakage.

[0013] 2. In existing cryogenic ball valves, the thrust pad is located at the end of the valve stem. Under operating conditions, it is in a low-temperature environment for a long time, which greatly increases the coefficient of friction and the torque. In contrast, the thrust pad of this structure is far away from the low-temperature environment and is in a normal temperature environment, which effectively reduces the coefficient of friction of the thrust pad and thus reduces the torque.

[0014] 3. When the thrust pad is at the lower end, the upper part of the valve stem is in an unpositioned state and may swing. During the opening and closing process, the valve stem may get stuck, affecting the torque. However, with this structure, the thrust pad is located at the upper part of the valve stem and forms a two-end positioning with the lower bearing, which avoids the swinging of the valve stem and reduces the impact of the valve stem on the torque. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall structure of the ball valve described in this utility model;

[0016] Figure 2 This utility model Figure 1 A magnified view of a section at point A in the middle;

[0017] In the diagram: 1. Valve stem; 2. Gland and top flange bolts; 3. Dustproof O-ring; 4. Top flange; 5. Disc spring; 6. Pressure plate and gland flange bolts; 7. Pressure plate; 8. Pressure sleeve; 9. Gland flange; 10. Packing; 11. Packing gasket; 12. Plug ring; 13. Thrust pad; 14. Ball; 15. Connecting keyway; 16. Valve stem step; 17. Protrusion; 18. Gland flange step. Detailed Implementation

[0018] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0019] refer to Figure 1-2As shown, the present invention provides a low-torque cryogenic ball valve, including a valve stem 1. The lower end of the valve stem 1 is connected to a ball 14 and can drive the ball 14 to rotate (the connection method is a conventional connection, so it is not described in detail). The upper end of the valve stem 1 is provided with a connecting keyway 15 for connecting to an actuator (not shown in the figure), and is connected to the actuator by a key connection.

[0020] A valve stem step 16 is provided on the side surface of the valve stem 1 away from the ball 14, and the valve cover step 16 is located below the connecting keyway 15.

[0021] A thrust pad 13 is fitted on the valve stem step 16. At the same time, a pressure cover flange 9 is fitted on the outside of the valve stem 1. A ring of protrusions 17 is provided on the inner surface of the pressure cover flange 9. The thrust pad 13 is located between the protrusions 17 and the valve cover step 16, thereby fixing the position of the thrust pad 13. The thrust pad 13 abuts against both the protrusions 17 and the step.

[0022] Meanwhile, between the valve stem 1 and the gland flange 9, there is also a plug ring 12 located above the protrusion 17 and abutting against the protrusion, a packing gasket ring 11 located above the plug ring 12, a packing 10 located above the packing gasket ring 11 and abutting against the packing gasket ring 11, a pressure sleeve 8 located above the packing 10 and abutting against the packing 10, and a pressure plate 7 located above the pressure sleeve 8 and abutting against the pressure sleeve 8. The pressure plate 7 abuts against the pressure sleeve 8, thereby abutting against the packing and the packing gasket ring in sequence.

[0023] Meanwhile, the inner surface of the gland flange 9 is provided with a gland flange step 18, and multiple gland flange screw slots are provided at equal angles and intervals on the gland flange step 18. At the same time, the pressure plate is provided with pressure plate bolt holes at corresponding positions.

[0024] The pressure plate and pressure plate flange screws 6 are internally threaded through the screw groove and bolt hole of the pressure plate flange. The pressure plate 7 is pressed by the pressure plate and pressure plate flange screws 6, so that the pressure plate 7 is fixed on the pressure plate flange 9. Then, by tightening the pressure plate and pressure plate flange screws 6, the pressure sleeve 8, packing 10 and packing gasket 11 are pressed from top to bottom. A disc spring 5 is provided between the pressure plate and pressure plate flange screws 6 and the pressure plate 7 to prevent the pressure plate and pressure plate flange screws 6 from loosening.

[0025] In this embodiment, a top flange 4 is also fitted around the valve stem 1, and the top flange 4 is fixedly mounted on the upper surface of the gland flange 9. Specifically, the upper surface of the top flange 4 is provided with multiple top flange screw holes, and the upper surface of the gland flange 9 is provided with multiple gland flange screw grooves that cooperate with the top flange screw holes. The gland flange 9 and the top flange 4 are fixedly connected by multiple glands and top flange screws 2, thereby ensuring the connection strength between the two.

[0026] Meanwhile, a dustproof groove is formed on the top flange 4, and a dustproof O-ring 3 is embedded in the dustproof groove. The dustproof O-ring 3 prevents dust and moisture from entering between the actuator and the top flange 4.

[0027] In this embodiment, the mating surface between the pressure sleeve 8 and the pressure plate 7 is a conical surface. The conical surface can form a self-centering effect and produce a tightening effect as it is pressed, further preventing the pressure sleeve 8 from loosening.

[0028] During installation, the thrust pad 13 is fitted onto the valve stem 1; the gland flange 9 is fitted onto the valve stem 1; the plug ring 12 is installed between the valve stem 1 and the gland flange 9 and abuts against the protrusion 17; then the packing ring 11, packing 10, gland sleeve 8, and pressure plate 7 are installed between the valve stem 1 and the gland flange 9 in sequence; the position of the pressure plate 7 is then fixed by the disc spring 5 and the pressure plate and gland flange screws 6; the pressure plate 7 and gland flange 9 screws 6 are then tightened; then the top flange 4 is installed onto the gland flange 9; the gland and top flange screws 2 are tightened; and the dustproof O-ring 3 is installed into the dustproof groove of the top flange 4.

[0029] When the valve is in use, the pressure plate and gland flange screw 6 and the gland and top flange screw 2 are independent. During the opening and closing process, even if the top flange 4 is loose, it will not affect the pressure plate and gland flange screw 6, so there will be no external leakage of the valve stem 1.

[0030] Meanwhile, during operation, the thrust pad 13 is far away from the sphere and thus far away from the low-temperature environment, which greatly reduces the coefficient of friction and thus significantly reduces the torque. This provides a basis for selecting actuators with smaller torque and improves product competitiveness.

[0031] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A low torque ultra-low temperature ball valve, characterized by: The valve includes a valve stem, a thrust pad is fitted on the upper part of the valve stem, a gland flange and a top flange are fitted on the outside of the valve stem, the top flange is located above the gland flange and is fixedly connected to the gland flange, and a plug ring, a packing gasket, packing, a pressure sleeve and a pressure plate are arranged from bottom to top between the valve stem and the gland flange, the pressure plate being fixed to the gland flange.

2. The low-torque cryogenic ball valve according to claim 1, characterized in that: A dustproof groove is provided on the top flange, and a dustproof O-ring is embedded in the dustproof groove.

3. The low-torque cryogenic ball valve according to claim 1, characterized in that: The gland flange and the top flange are fixedly connected by multiple glands and top flange screws.

4. The low-torque cryogenic ball valve according to claim 1, characterized in that: The pressure plate and the pressure cover flange are fixedly connected by multiple pressure plates and pressure cover flange screws.

5. A low-torque cryogenic ball valve according to claim 1, characterized in that: A disc spring is provided between the pressure plate and the flange screws of the pressure plate.

6. The low-torque cryogenic ball valve according to claim 1, characterized in that: The mating surface between the pressure sleeve and the pressure plate is a conical surface.

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