Assembly method and assembly tool for ultra-low temperature ball valve seat seal ring

Abstract

The present invention is an assembly method and assembly tool for a cryogenic ball valve seat seal ring. The cryogenic ball valve seat seal ring is used for sealing sleeves arranged in the mounting groove of a metal valve seat. The cryogenic ball valve seat seal ring is a PCTFE seal ring. At room temperature, the inner diameter of the PCTFE seal ring is larger than the inner diameter of the mounting groove, and the outer diameter of the PCTFE seal ring is larger than the outer diameter of the mounting groove. The assembly method for the cryogenic ball valve seat seal ring comprises: in a constant temperature processing workshop, installing the cryogenic ball valve seat seal ring into a cold assembly tool, precooling the cold assembly tool and the cryogenic ball valve seat seal ring, and installing the cryogenic ball valve seat seal ring into the mounting groove of the metal valve seat using the cold assembly tool after precooling. The present invention solves the leakage risk of traditional cryogenic ball valves when they are used as isolation valves and closed for a long time during actual working conditions.

Description

Technical Field

[0001] The invention relates to the technical field of ultra-low temperature ball valves, and in particular to an assembly method and assembly tooling for an ultra-low temperature ball valve seat sealing ring. Background Art

[0002] As an efficient, low-carbon and clean fossil energy, natural gas has begun to replace primary energy sources such as coal and oil in many energy-using fields. It is an important bridge for the transition to a new energy system and a realistic choice for promoting energy transformation. Among them, LNG has gradually become the most active form of natural gas supply due to its advantages of easy transportation, diversified entities, strong flexibility, safety and efficiency. According to incomplete statistics, among the various types of valves used in liquefied natural gas (LNG) receiving stations, the number of ultra-low temperature ball valves accounts for more than 60%, and is widely used.

[0003] The seal between the ball and the seat of the cryogenic ball valve is achieved by a sealing ring made of PCTFE (polychlorotrifluoroethylene). Figure 4 , Figure 5 As shown, the PCTFE sealing ring needs to be embedded in the metal valve seat. The PCTFE sealing ring and the metal valve seat are sealed by the end face, and PCTFE is usually installed in the metal valve seat at ambient temperature. Since the ultra-low temperature ball valve works at -162℃, and PCTFE is a non-metallic material, its linear expansion coefficient is very different from that of the metal valve seat, especially at ultra-low temperatures. The difference in linear expansion coefficients of the two is even greater, and PCTFE hardens at ultra-low temperatures, resulting in the inability to achieve reliable sealing between the PCTFE sealing ring and the metal valve seat at ultra-low temperatures, and there is a potential leakage channel.

[0004] At present, the conventional PCTFE sealing ring for ultra-low temperature ball valves is usually processed with tooth-shaped grooves on the contact surface with the metal valve seat, such as Figure 4 , Figure 5 As shown, a labyrinth-like seal is formed. The disadvantage of this structure is that the step-by-step pressure reduction of the end face toothed groove can only ensure that the valve does not leak during the limited pressure holding time during the type test. However, in actual working conditions, when the ultra-low temperature ball valve is used as an isolation valve, it needs to be closed for a long time. In a low temperature environment, the traditional PCTFE sealing ring is constrained in the metal valve seat ring groove, and the toothed groove on its back cannot effectively contact the bottom surface of the metal valve seat ring groove, resulting in the failure of the labyrinth seal, and leakage will always occur, which brings safety hazards to the inspection and maintenance of the LNG receiving station.

[0005] Therefore, the inventor, relying on many years of experience and practice in related industries, proposes an assembly method and assembly tooling for a seat sealing ring of an ultra-low temperature ball valve to overcome the defects of the prior art. Summary of the invention

[0006] The purpose of the present invention is to provide an assembly method and assembly tool for a seat sealing ring of a cryogenic ball valve, so as to solve the leakage risk of a traditional cryogenic ball valve when used as an isolation valve and closed for a long time during actual working conditions. Based on the sealing structure of a traditional cryogenic ball valve sealing ring and a metal valve seat, a seat sealing ring of a cryogenic ball valve is reasonably arranged. Under the action of the medium force, the toothed groove on the back of the PCTFE sealing ring is in full contact with the bottom of the mounting groove of the metal valve seat. The PCTFE sealing ring is installed by a cold assembly process, thereby reducing the potential risk of the PCTFE sealing ring being cut when the PCTFE sealing ring is directly pressed into the mounting groove of the metal valve seat.

[0007] The object of the present invention can be achieved in this way: an assembly method of a seat seal ring of a cryogenic ball valve, wherein the seat seal ring of the cryogenic ball valve is a PCTFE seal ring; at room temperature, the inner diameter of the PCTFE seal ring is larger than the inner diameter of the mounting groove, and the outer diameter of the PCTFE seal ring is larger than the outer diameter of the mounting groove; under ultra-low temperature conditions, there is an appropriate amount of clearance between the PCTFE seal ring and the mounting groove of the metal valve seat, so that under the action of the medium force, the toothed groove on the back of the PCTFE seal ring and the bottom of the mounting groove of the metal valve seat are in full contact;

[0008] The assembly method of the ultra-low temperature ball valve seat sealing ring includes: processing the ultra-low temperature ball valve seat sealing ring in a constant temperature processing workshop and installing it into a cold assembly tool, pre-cooling the cold assembly tool and the ultra-low temperature ball valve seat sealing ring, and after pre-cooling, using the cold assembly tool to install the ultra-low temperature ball valve seat sealing ring into the installation groove of the metal valve seat.

[0009] In a preferred embodiment of the present invention, the cold assembly tooling and the ultra-low temperature ball valve seat sealing ring are sealed and pre-cooled in a liquid nitrogen cooling tooling.

[0010] In a preferred embodiment of the present invention, the cold assembly tool includes an assembly tool body, a sealing ring accommodating groove is arranged in the assembly tool body, a sealing ring fixing structure is arranged on the side wall of the assembly tool body, and a disassembly through hole connected to the sealing ring accommodating groove is also arranged on the assembly tool body, and the disassembly through hole is used to remove the valve seat sealing ring of the ultra-low temperature ball valve from the assembly tool body; a locking groove that can be locked to the end of the metal valve seat is arranged at the bottom of the assembly tool body; and a lifting ring is detachably connected to the assembly tool body.

[0011] In a preferred embodiment of the present invention, a lateral through hole is provided on the side wall of the assembly tool body, and the lateral through hole is connected to the sealing ring accommodating groove; the sealing ring fixing structure includes a steel ball, a spring and a fastening screw which are sequentially arranged in the lateral through hole, and the steel ball can be pressed against the side wall of the ultra-low temperature ball valve seat sealing ring under the action of the fastening screw and the spring.

[0012] In a preferred embodiment of the present invention, installing the valve seat seal ring of the cryogenic ball valve into the cold assembly tool comprises the following steps:

[0013] Step a, installing the ultra-low temperature ball valve seat sealing ring into the sealing ring receiving groove;

[0014] Step b, sequentially inserting steel balls and springs into the lateral through holes of the self-assembly tool body;

[0015] Step c, screwing the fastening screw into the lateral through hole, and tightening it according to the set spring contraction amount and tightening torque, so that the valve seat sealing ring of the ultra-low temperature ball valve can be fixed in the sealing ring receiving groove;

[0016] Step d: Connect the lifting ring to the assembly tool body.

[0017] In a preferred embodiment of the present invention, the liquid nitrogen cooling tooling includes a cooling shell, a liquid nitrogen vapor chamber is arranged in the cooling shell, a removable and sealable insulation cover is arranged on the top of the cooling shell, and an expanded polytetrafluoroethylene sealing gasket is arranged between the insulation cover and the cooling shell.

[0018] In a preferred embodiment of the present invention, the cold assembly tooling and the cryogenic ball valve seat seal ring are precooled, comprising the following steps:

[0019] Step a, placing the cold assembly tooling loaded with the ultra-low temperature ball valve seat sealing ring into the liquid nitrogen steam chamber;

[0020] Step b, installing an expanded polytetrafluoroethylene sealing gasket on the top of the cooling shell;

[0021] Step c, sealing and connecting the heat-insulating cover;

[0022] Step d, pre-cooling the cold assembly tooling and the ultra-low temperature ball valve seat seal ring for a set time.

[0023] In a preferred embodiment of the present invention, the installation of the cryogenic ball valve seat seal ring into the installation groove of the metal valve seat using a cold assembly tool comprises the following steps:

[0024] Step a, place the metal valve seat on the bench platform;

[0025] Step b, open the insulation cover of the liquid nitrogen cooling tooling, quickly lift out the cold assembly tooling and blow it with instrument air;

[0026] Step c, align the retaining notch of the cold assembly tool with the end of the metal valve seat and lightly lean against the end thereof;

[0027] Step d, removing the sealing ring fixing structure from the self-cooling assembly tooling;

[0028] Step e: Use a tool to push the valve seat sealing ring of the cryogenic ball valve through the disassembly through-hole, so that it leaves the assembly tool body and enters the installation groove of the metal valve seat;

[0029] Step f: Use instrument air to purge around the valve seat seal ring of the cryogenic ball valve until the temperature of the valve seat seal ring of the cryogenic ball valve approaches the temperature of the constant temperature chamber.

[0030] The object of the present invention can also be achieved in this way: an assembly tool for a seat sealing ring of a cryogenic ball valve, comprising a cold assembly tool, the cold assembly tool comprising an assembly tool body, a sealing ring accommodating groove is arranged in the assembly tool body, a sealing ring fixing structure is arranged on the side wall of the assembly tool body, a disassembly through hole connected to the sealing ring accommodating groove is also arranged on the assembly tool body, the disassembly through hole is used to disassemble the seat sealing ring of the cryogenic ball valve from the assembly tool body; a locking groove which can be locked to the end of a metal valve seat is arranged at the bottom of the assembly tool body; and a lifting ring is detachably connected to the assembly tool body.

[0031] In a preferred embodiment of the present invention, a lateral through hole is provided on the side wall of the assembly tool body, and the lateral through hole is connected to the sealing ring accommodating groove; the sealing ring fixing structure includes a steel ball, a spring and a fastening screw which are sequentially arranged in the lateral through hole, and the steel ball can be pressed against the side wall of the ultra-low temperature ball valve seat sealing ring under the action of the fastening screw and the spring.

[0032] As described above, the assembly method and assembly tool of the ultra-low temperature ball valve seat seal ring of the present invention have the following beneficial effects:

[0033] The assembly method and assembly tool of the ultra-low temperature ball valve seat sealing ring of the present invention solve the leakage risk of the traditional ultra-low temperature ball valve when it is used as an isolation valve and closed for a long time during actual working conditions. Based on the sealing structure of the traditional ultra-low temperature ball valve sealing ring and the metal valve seat, the ultra-low temperature ball valve seat sealing ring is reasonably arranged to ensure that under ultra-low temperature conditions, there is an appropriate amount of gap between the PCTFE sealing ring and the installation groove of the metal valve seat, so that under the action of the medium force, the toothed groove on the back of the PCTFE sealing ring and the bottom of the installation groove of the metal valve seat are completely in contact, and even under the pressure fluctuation of the gas-liquid two-phase pulsating flow, the labyrinth seal can be achieved, thereby eliminating the leakage risk;

[0034] A constant temperature processing method is adopted to reduce the influence of ambient temperature on the size of the PCTFE sealing ring; since the outer diameter of the PCTFE sealing ring is much larger than the outer diameter of the mounting groove of the metal valve seat, a cold assembly process is adopted to install the PCTFE sealing ring, thereby reducing the potential risk of the PCTFE sealing ring being cut when the PCTFE sealing ring is directly pressed into the mounting groove of the metal valve seat; the assembly method and assembly tooling of the ultra-low temperature ball valve seat sealing ring of the present invention can be used for ultra-low temperature (≤-101°C) media of liquid phase flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The following drawings are only intended to illustrate and explain the present invention, and are not intended to limit the scope of the present invention.

[0036] in:

[0037] Figure 1 : It is a schematic diagram of the cold assembly tooling for installing the ultra-low temperature ball valve seat sealing ring of the present invention.

[0038] Figure 2 : is a schematic diagram of a cold assembly tool for installing a cryogenic ball valve seat sealing ring in a liquid nitrogen vapor chamber according to the present invention.

[0039] Figure 3 : A schematic diagram of installing a cryogenic ball valve seat sealing ring onto a metal valve seat using the cold assembly tool of the present invention.

[0040] Figure 4 : Schematic diagram of the traditional ultra-low temperature ball valve PCTFE sealing ring after installation.

[0041] Figure 5 :for Figure 4 Enlarged view of point A in the middle.

[0042] In the figure:

[0043] 100. Cold assembly tooling; 200. Liquid nitrogen cooling tooling;

[0044] 1. Assembly tool body; 11. Sealing ring accommodating groove; 12. Disassembly through hole; 13. Stop notch; 14. Lateral through hole; 15. Latch;

[0045] 21. Steel ball; 22. Spring; 23. Fastening screw;

[0046] 3. Rings;

[0047] 4. Cooling shell; 41. Liquid nitrogen steam chamber; 42. Liquid nitrogen chamber; 43. Sand hole; 44. Limit block;

[0048] 5. Insulation cover;

[0049] 6. Expanded PTFE gasket;

[0050] 7. Inner tank; 71. Convection orifice plate; 711. Convection hole;

[0051] 8. Pearl sand;

[0052] 91. Sealing ring of ultra-low temperature ball valve seat; 92. Metal valve seat; 93. Valve body; 94. Pan plug; 95. Spring seat; 96. Spring; 97. Threaded seat. DETAILED DESCRIPTION

[0053] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described with reference to the accompanying drawings.

[0054] The specific embodiments of the present invention described herein are only used to explain the purpose of the present invention and cannot be understood as limiting the present invention in any way. Under the guidance of the present invention, technicians can conceive of any possible variations based on the present invention, which should be considered to belong to the scope of the present invention. It should be noted that when an element is referred to as "arranged on" another element, it can be directly on the other element or there can also be a central element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be a central element at the same time. The terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a mechanical connection or an electrical connection, or it can be the internal communication of two elements, it can be directly connected, or it can be indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances. The terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used herein are only for illustrative purposes and do not represent the only implementation method.

[0055] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0056] The present invention provides a cryogenic ball valve seat sealing ring 91, which is used for sealing and sleeved in the mounting groove of a metal valve seat 92. The cryogenic ball valve seat sealing ring is a PCTFE sealing ring. At room temperature (20°C), the inner diameter of the PCTFE sealing ring is larger than the inner diameter of the mounting groove, and the outer diameter of the PCTFE sealing ring is larger than the outer diameter of the mounting groove.

[0057] The linear expansion coefficients of metal valve seats and non-metallic sealing rings (PCTFE sealing rings) are very different. The linear expansion coefficient of PCTFE sealing rings is much larger than that of metal valve seats (CF3M metal valve seats). The linear expansion coefficient of PCTFE sealing rings is 4.5x10 -5 K -1 , while the linear expansion coefficient of CF3M is 15.3x10 -6 K -1 It can be seen that the linear expansion coefficient of the PCTFE sealing ring is 2.49 times that of CF3M. If the inner diameter and outer diameter of the PCTFE sealing ring are not adjusted, in an ultra-low temperature environment, the PCTFE sealing ring is installed in the mounting groove (ring groove) of the metal valve seat. As mentioned above, the shrinkage of the PCFFE sealing ring is greater than the shrinkage of the mounting groove (ring groove) of the metal valve seat. The inner wall of the PCTFE sealing ring is tightly held in the mounting groove (ring groove), while its outer diameter has a certain gap with the outer wall of the metal valve seat (the outer diameter surface of the mounting groove of the metal valve seat). This causes the PCTFE sealing ring to be constrained in the mounting groove (ring groove) of the metal valve seat, and the toothed groove on its back (existing technology) cannot effectively contact the bottom surface of the mounting groove (ring groove) of the metal valve seat, resulting in sealing failure.

[0058] The design principle of the ultra-low temperature ball valve seat sealing ring of the present invention is to ensure, through calculation, that under ultra-low temperature conditions, there is an appropriate gap between the PCTFE sealing ring and the mounting groove of the metal valve seat, so that under the action of the medium force, the toothed groove on the back of the PCTFE sealing ring and the bottom of the mounting groove of the metal valve seat are in complete contact, and even in the case of pressure fluctuations of the gas-liquid two-phase pulsating flow, a labyrinth seal can be achieved, thereby eliminating the risk of leakage.

[0059] Since PCTFE sealing rings are sensitive to ambient temperature, practice has proved that ambient temperature has a great influence on the size of PCTFE sealing rings. For example, a PCTFE sealing ring that is turned at noon in summer is measured again in the afternoon. The change in the inner and outer diameters of the PCTFE sealing ring is nearly 1mm, which cannot achieve the expected ideal effect of the PCTFE sealing ring at low temperature. Therefore, it is necessary to process it in a constant temperature processing workshop.

[0060] Considering that the measurement reference temperature is 20℃ (normal temperature) and the set temperature of the constant temperature room is 20℃±5℃, the PCTFE sealing ring and metal valve seat are processed and measured in the constant temperature processing workshop.

[0061] The present invention also provides a method for assembling a cryogenic ball valve seat seal ring, comprising: in a constant temperature processing workshop, processing the cryogenic ball valve seat seal ring 91 and installing it into a cold assembly tool 100 (such as Figure 1 As shown), the cold assembly tool 100 and the ultra-low temperature ball valve seat sealing ring 91 are pre-cooled (as shown Figure 2As shown), after precooling (precooling setting time), use the cold assembly tool 100 to install the ultra-low temperature ball valve seat sealing ring 91 into the installation groove of the metal valve seat 92 (as shown Figure 3 shown).

[0062] Since the outer diameter of the PCTFE sealing ring is much larger than the outer diameter of the mounting groove of the metal valve seat, there is a potential risk of cutting the PCTFE sealing ring when pressing the PCTFE sealing ring directly into the mounting groove of the metal valve seat with a hydraulic press. Therefore, it is necessary to use a cold assembly process to install the PCTFE sealing ring.

[0063] Further, if Figure 2 As shown, the cold assembly tool 100 and the ultra-low temperature ball valve seat sealing ring are sealed and pre-cooled in the liquid nitrogen cooling tool 200.

[0064] Further, if Figure 1 As shown, the cold assembly tool 100 includes an assembly tool body 1, a sealing ring accommodating groove 11 is arranged in the assembly tool body 1, a sealing ring fixing structure is arranged on the side wall of the assembly tool body 1, and a disassembly through hole 12 connected to the sealing ring accommodating groove 11 is also arranged on the assembly tool body 1, and the disassembly through hole 12 is used to disassemble the valve seat sealing ring of the ultra-low temperature ball valve from the assembly tool body; a locking groove 13 that can be locked to the end of the metal valve seat is arranged at the bottom of the assembly tool body 1; and a lifting ring 3 is detachably connected to the assembly tool body 1.

[0065] Further, if Figure 1 As shown, a lateral through hole 14 is provided on the side wall of the assembly tool body 1, and the lateral through hole 14 is connected to the sealing ring accommodating groove 11; the sealing ring fixing structure includes a steel ball 21, a spring 22 and a fastening screw 23 (hexagon socket screw) which are sequentially arranged in the lateral through hole, and the steel ball 21 can be pressed against the side wall of the sealing ring of the ultra-low temperature ball valve seat under the action of the fastening screw 23 and the spring 22.

[0066] Further, installing the ultra-low temperature ball valve seat seal ring into the cold assembly tool 100 includes the following steps:

[0067] Step a, installing the ultra-low temperature ball valve seat sealing ring 91 into the sealing ring receiving groove 11;

[0068] Step b, sequentially insert the steel ball 21 and the spring 22 into the lateral through hole 14 of the self-assembly tool body 1;

[0069] Step c, screw the fastening screw 23 into the lateral through hole 14, and tighten it according to the set spring contraction amount and tightening torque, so that the valve seat sealing ring of the ultra-low temperature ball valve can be fixed in the sealing ring accommodating groove 11;

[0070] Step d: Connect the lifting ring 3 to the assembly tool body 1.

[0071] Further, if Figure 2 As shown, the liquid nitrogen cooling tool 200 includes a cooling shell 4, a liquid nitrogen vapor chamber 41 is arranged inside the cooling shell 4, a detachable and sealable insulation cover 5 is arranged on the top of the cooling shell 4, and an expanded polytetrafluoroethylene sealing gasket 6 is arranged between the insulation cover 5 and the cooling shell 4.

[0072] Specifically, Figure 2 As shown, an inner liner 7 is arranged in the cooling shell 4, pearl sand 8 is filled between the inner liner 7 and the cooling shell 4, a convection orifice plate 71 is arranged in the inner liner 7, and convection holes 711 are arranged on the convection orifice plate 71; a sand passing hole 43 is arranged between the inner liner 7 and the cooling shell 4, and a limit block 44 is arranged in the sand passing hole; a liquid nitrogen chamber 42 is formed below the convection orifice plate 71, and liquid nitrogen is prefabricated in the liquid nitrogen chamber 42; a liquid nitrogen steam chamber 41 is formed above the convection orifice plate 71, and a cold assembly tooling loaded with a valve seat sealing ring of an ultra-low temperature ball valve is placed on the convection orifice plate 71, and the temperature is reduced by cooling with liquid nitrogen steam.

[0073] Further, the cold assembly tooling and the cryogenic ball valve seat seal ring are precooled, including the following steps:

[0074] Step a, placing the cold assembly tooling loaded with the ultra-low temperature ball valve seat sealing ring into the liquid nitrogen steam chamber 41;

[0075] Step b, installing an expanded polytetrafluoroethylene sealing gasket 6 on the top of the cooling shell 4;

[0076] Step c, sealing and connecting the heat-insulating cover 5;

[0077] Step d: Pre-cool the cold assembly tooling and the ultra-low temperature ball valve seat seal ring for a set time. The cooling time is determined according to the size of the pre-cooled workpiece, and the cooling time is 30 to 50 minutes.

[0078] Further, if Figure 3 As shown, the following steps are included to install the seat seal ring of the cryogenic ball valve into the mounting groove of the metal valve seat using the cold assembly tool:

[0079] Step a, place the metal valve seat on the bench platform;

[0080] Step b, open the insulation cover 5 of the liquid nitrogen cooling tooling 200, quickly lift out the cold assembly tooling 100 and purge it with instrument air;

[0081] Step c, align the retaining notch 13 of the cold assembly tool 100 with the end of the metal valve seat (the thread outer diameter of the end of the valve seat) and lightly lean against the end;

[0082] Step d, remove the sealing ring fixing structure from the self-cooling assembly tool; specifically, remove each fastening screw 23 with a hexagon socket screw wrench, and take out each spring 22 and steel ball 21;

[0083] Step e: Use a tool to push the valve seat sealing ring of the cryogenic ball valve through the disassembly through-hole, so that it leaves the assembly tool body and enters the installation groove of the metal valve seat;

[0084] Specifically, two persons use the latch 15 to press the PCTFE sealing ring along the corresponding disassembly through hole 12 (latch hole) at 180° opposite sides, so that the PCTFE sealing ring is installed into the installation groove (ring groove) of the metal valve seat;

[0085] Step f: Use instrument air to purge around the valve seat seal ring of the cryogenic ball valve until the temperature of the valve seat seal ring of the cryogenic ball valve approaches the temperature of the constant temperature chamber.

[0086] The present invention provides an assembly tool for a cryogenic ball valve seat seal ring, including a cold assembly tool 100, such as Figure 1 As shown, the cold assembly tool 100 includes an assembly tool body 1, a sealing ring accommodating groove 11 is arranged in the assembly tool body 1, a sealing ring fixing structure is arranged on the side wall of the assembly tool body 1, and a disassembly through hole 12 connected to the sealing ring accommodating groove 11 is also arranged on the assembly tool body 1, and the disassembly through hole 12 is used to disassemble the valve seat sealing ring of the ultra-low temperature ball valve from the assembly tool body 1; a locking groove 13 which can be locked to the end of the metal valve seat is arranged at the bottom of the assembly tool body 1; and a lifting ring 3 is detachably connected to the assembly tool body 1.

[0087] Furthermore, a lateral through hole 14 is provided on the side wall of the assembly tool body 1, and the lateral through hole 14 is connected to the sealing ring accommodating groove 11; the sealing ring fixing structure includes a steel ball 21, a spring 22 and a fastening screw 23 which are sequentially arranged in the lateral through hole 14, and the steel ball 21 can be pressed against the side wall of the sealing ring of the ultra-low temperature ball valve seat under the action of the fastening screw 23 and the spring 22.

[0088] As described above, the assembly method and assembly tool of the ultra-low temperature ball valve seat seal ring of the present invention have the following beneficial effects:

[0089] The assembly method and assembly tool of the ultra-low temperature ball valve seat sealing ring of the present invention solve the leakage risk of the traditional ultra-low temperature ball valve when it is used as an isolation valve and closed for a long time during actual working conditions. Based on the sealing structure of the traditional ultra-low temperature ball valve sealing ring and the metal valve seat, the ultra-low temperature ball valve seat sealing ring is reasonably arranged to ensure that under ultra-low temperature conditions, there is an appropriate amount of gap between the PCTFE sealing ring and the installation groove of the metal valve seat, so that under the action of the medium force, the toothed groove on the back of the PCTFE sealing ring and the bottom of the installation groove of the metal valve seat are completely in contact, and even under the pressure fluctuation of the gas-liquid two-phase pulsating flow, the labyrinth seal can be achieved, thereby eliminating the leakage risk;

[0090] A constant temperature processing method is adopted to reduce the influence of ambient temperature on the size of the PCTFE sealing ring; since the outer diameter of the PCTFE sealing ring is much larger than the outer diameter of the mounting groove of the metal valve seat, a cold assembly process is adopted to install the PCTFE sealing ring, thereby reducing the potential risk of the PCTFE sealing ring being cut when the PCTFE sealing ring is directly pressed into the mounting groove of the metal valve seat; the assembly method and assembly tooling of the ultra-low temperature ball valve seat sealing ring of the present invention can be used for ultra-low temperature (≤-101°C) media of liquid phase flow.

[0091] The above description is only an illustrative embodiment of the present invention and is not intended to limit the scope of the present invention. Any equivalent changes and modifications made by any person skilled in the art without departing from the concept and principle of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A method for assembling a seat seal ring of a cryogenic ball valve, characterized in that: The ultra-low temperature ball valve seat sealing ring is a PCTFE sealing ring; at room temperature, the inner diameter of the PCTFE sealing ring is larger than the inner diameter of the mounting groove, and the outer diameter of the PCTFE sealing ring is larger than the outer diameter of the mounting groove. Under ultra-low temperature conditions, there is an appropriate amount of clearance between the PCTFE sealing ring and the mounting groove of the metal valve seat, so that under the action of the medium force, the toothed groove on the back of the PCTFE sealing ring and the bottom of the mounting groove of the metal valve seat are in full contact; The assembly method of the ultra-low temperature ball valve seat sealing ring includes: processing the ultra-low temperature ball valve seat sealing ring in a constant temperature processing workshop and installing it into a cold assembly tool, pre-cooling the cold assembly tool and the ultra-low temperature ball valve seat sealing ring, and after pre-cooling, using the cold assembly tool to install the ultra-low temperature ball valve seat sealing ring into the installation groove of the metal valve seat.

2. The assembly method of the ultra-low temperature ball valve seat seal ring according to claim 1, characterized in that: The cold assembly tooling and the ultra-low temperature ball valve seat sealing ring are sealed and pre-cooled in a liquid nitrogen cooling tooling.

3. The method for assembling a seat seal ring of a cryogenic ball valve according to claim 1 or 2, characterized in that: The cold assembly tool comprises an assembly tool body, a sealing ring accommodating groove is arranged in the assembly tool body, a sealing ring fixing structure is arranged on the side wall of the assembly tool body, and a disassembly through hole connected to the sealing ring accommodating groove is also arranged on the assembly tool body, and the disassembly through hole is used to disassemble the valve seat sealing ring of the ultra-low temperature ball valve from the assembly tool body; a locking groove which can be locked to the end of the metal valve seat is arranged at the bottom of the assembly tool body; and a lifting ring is detachably connected to the assembly tool body.

4. The method for assembling a seat seal ring of a cryogenic ball valve according to claim 3, characterized in that: A lateral through hole is arranged on the side wall of the assembly tool body, and the lateral through hole is connected to the sealing ring accommodating groove; the sealing ring fixing structure includes a steel ball, a spring and a fastening screw which are arranged in sequence in the lateral through hole, and the steel ball can be pressed against the side wall of the sealing ring of the ultra-low temperature ball valve seat under the action of the fastening screw and the spring.

5. The method for assembling a seat seal ring of a cryogenic ball valve according to claim 4, characterized in that: Installing the cryogenic ball valve seat seal into the cold assembly tooling includes the following steps: Step a, installing the ultra-low temperature ball valve seat sealing ring into the sealing ring receiving groove; Step b, sequentially inserting steel balls and springs into the lateral through holes of the self-assembly tool body; Step c, screwing the fastening screw into the lateral through hole, and tightening it according to the set spring contraction amount and tightening torque, so that the valve seat sealing ring of the ultra-low temperature ball valve can be fixed in the sealing ring receiving groove; Step d: Connect the lifting ring to the assembly tool body.

6. The method for assembling a seat seal ring of a cryogenic ball valve according to claim 2, characterized in that: The liquid nitrogen cooling tool comprises a cooling shell, a liquid nitrogen steam chamber is arranged in the cooling shell, a detachable and sealable heat preservation cover is arranged on the top of the cooling shell, and an expanded polytetrafluoroethylene sealing pad is arranged between the heat preservation cover and the cooling shell.

7. The method for assembling a seat seal ring of a cryogenic ball valve according to claim 6, characterized in that: The cold assembly tooling and the precooling of the ultra-low temperature ball valve seat seal ring include the following steps: Step a, placing the cold assembly tooling loaded with the ultra-low temperature ball valve seat sealing ring into the liquid nitrogen steam chamber; Step b, installing an expanded polytetrafluoroethylene sealing gasket on the top of the cooling shell; Step c, sealing and connecting the heat-insulating cover; Step d, pre-cooling the cold assembly tooling and the ultra-low temperature ball valve seat seal ring for a set time.

8. The method for assembling a seat seal ring of a cryogenic ball valve according to claim 3, characterized in that: The installation of the cryogenic ball valve seat seal ring into the metal valve seat mounting groove using the cold assembly tool includes the following steps: Step a, place the metal valve seat on the bench platform; Step b, open the insulation cover of the liquid nitrogen cooling tooling, quickly lift out the cold assembly tooling and blow it with instrument air; Step c, align the retaining notch of the cold assembly tool with the end of the metal valve seat and lightly lean against the end thereof; Step d, removing the sealing ring fixing structure from the self-cooling assembly tooling; Step e: Use a tool to push the valve seat sealing ring of the cryogenic ball valve through the disassembly through-hole, so that it leaves the assembly tool body and enters the installation groove of the metal valve seat; Step f: Use instrument air to purge around the valve seat seal ring of the cryogenic ball valve until the temperature of the valve seat seal ring of the cryogenic ball valve approaches the temperature of the constant temperature chamber.

9. An assembly tool for a cryogenic ball valve seat seal ring, characterized in that: Used to implement the assembly method of the ultra-low temperature ball valve seat sealing ring described in any one of claims 1-8; the assembly tool of the ultra-low temperature ball valve seat sealing ring includes a cold assembly tool, the cold assembly tool includes an assembly tool body, a sealing ring accommodating groove is arranged in the assembly tool body, a sealing ring fixing structure is arranged on the side wall of the assembly tool body, and a disassembly through hole connected to the sealing ring accommodating groove is also arranged on the assembly tool body, and the disassembly through hole is used to disassemble the ultra-low temperature ball valve seat sealing ring from the assembly tool body; a locking groove that can be locked to the end of the metal valve seat is arranged at the bottom of the assembly tool body; a lifting ring is detachably connected to the assembly tool body.

10. The assembly tool for the seat seal ring of a cryogenic ball valve according to claim 9, characterized in that: A lateral through hole is arranged on the side wall of the assembly tool body, and the lateral through hole is connected to the sealing ring accommodating groove; the sealing ring fixing structure includes a steel ball, a spring and a fastening screw which are arranged in sequence in the lateral through hole, and the steel ball can be pressed against the side wall of the sealing ring of the ultra-low temperature ball valve seat under the action of the fastening screw and the spring.

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