Gas leak repair method and gas leak repair structure

Abstract

To provide a gas leakage repairing method and a gas leakage repairing structure capable of repairing gas leakage by using an easily available component even in a state that gas is sealed in an apparatus.SOLUTION: The gas leakage repair method includes a step of winding the kite string 3 around the boundary between the device body 11 and the blind flange 12, a step of sealing the boundary and a part of the high nut 4 with the sealing material 6 in a state where the high nut 4 in which a part of the kite string 3 is accommodated is disposed so as to be in contact with the boundary, and a step of disposing the bolt 5 with an O-ring for sealing the high nut 4 inside the high nut 4.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a gas leak repair method and a gas leak repair structure. [Background technology]

[0002] Substations use gas circuit breakers and gas-insulated switchgear filled with sulfur hexafluoride (SF6), a greenhouse gas. Gas leaks can occur in these gas-filled devices due to aging. However, due to the influence of the leaking gas pressure, it is difficult to directly repair joints while gas continues to leak from the leaking point. To solve this problem, construction methods have been developed for repairing gas leaks from joints even when gas is leaking. For example, Patent Document 1 discloses a construction method in which a gas conduction band is wrapped around the joint, a gas vent plug with a gas release port is attached, the joint together with the gas conduction band and the gas vent plug are sealed with a sealant, and finally, the gas release port of the gas vent plug is sealed with a stop plug. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-66392 Summary of the Invention [Problem to be solved by the invention]

[0004] The method of Patent Document 1 uses special parts such as a gas conducting belt and a gas vent plug, which makes it difficult to widely spread the method to construction sites and also results in high costs associated with its introduction.

[0005] The present invention has been made based on this background, and aims to provide a gas leak repair method and gas leak repair structure that can repair a gas leak using easily available parts even when gas is sealed inside the equipment. [Means for solving the problem]

[0006] In order to achieve the above object, a gas leak repair method according to the present invention includes: A gas leak repair method for repairing gas leaks from joints in gas-filled equipment, comprising: a step of winding a string-like member around the boundary of the joint, the string-like member having a space formed therein to serve as a gas flow path; a step of sealing the joint and a portion of the first tubular member with a sealant in a state in which a first tubular member having a portion of the string-shaped member housed therein is placed so as to be in contact with the joint; disposing a first sealing member inside the first cylindrical member to seal the first cylindrical member; Includes: [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a gas leak repair method and gas leak repair structure that can repair a gas leak using easily available parts even when gas is sealed inside the equipment. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing a configuration of a gas circuit breaker according to an embodiment of the present invention; [Figure 2] FIG. 2 is a diagram showing a first step of a gas leak repair method according to an embodiment of the present invention. [Figure 3] FIG. 4 is a diagram showing a second step of the gas leak repair method according to the embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing a third step of the gas leak repair method according to the embodiment of the present invention. [Figure 5] FIG. 4 is a diagram showing a fourth step of the gas leak repair method according to the embodiment of the present invention. [Figure 6] FIG. 4 is a diagram showing a fifth step of the gas leak repair method according to the embodiment of the present invention. [Figure 7] FIG. 10 is a diagram showing a sixth step of the gas leak repair method according to the embodiment of the present invention. [Figure 8]10A and 10B are diagrams showing the configuration of a cylindrical member according to a modified example of the present invention. [Figure 9] FIG. 10 is a cross-sectional view showing the configuration of a gas leak repair structure according to a modified example of the present invention. [Figure 10] FIG. 2 is a diagram showing the configuration of a test device in an example. [Figure 11] FIG. 1 is a photograph of the appearance of a modified high-nut test device and an O-ring-equipped bolt in an example. DETAILED DESCRIPTION OF THE INVENTION

[0009] A gas leak repair method and a gas leak repair structure according to an embodiment of the present invention will be described in detail below with reference to the drawings. In each drawing, the same or equivalent parts are designated by the same reference numerals.

[0010] The gas leak repair method according to the embodiment is a method for repairing a gas leak from a joint of a gas-filled device while the gas is filled in the gas-filled device. The joint is a point where parts are joined together so as to prevent leakage of the gas sealed inside the gas-filled device, such as a point where a flange is joined to the device body or a point where flanges are joined together. The joint may be sealed with or without a packing. The following description will be given taking as an example a case where a gas circuit breaker is used as the gas-filled device.

[0011] The gas circuit breaker according to the embodiment is a gas circuit breaker that switches current in an insulating gas (insulating gas). The insulating gas is, for example, SF6 gas. SF6 gas has approximately three times the insulating performance and approximately 100 times the arc-extinguishing capability of air. As shown in FIG. 1, the gas circuit breaker 10 includes a device body 11 filled with insulating gas, a pair of closing flanges 12 detachably joined to both end faces of the device body 11, bolts 13 that attach each closing flange 12 to the device body 11, and a stand 14 that supports the device body 11 from below.

[0012] The closing flange 12 has a plurality of through holes arranged circumferentially, through which the bolts 13 can be inserted, and the device body 11 has a plurality of female threaded holes arranged circumferentially, through which the bolts 13 inserted into the through holes of the closing flange 12 can be screwed. A packing 15 is disposed between the device body 11 and the closing flange 12 to prevent gas leakage. If the packing 15 deteriorates over time and loses its elasticity, gas leakage will occur from the joint between the device body 11 and the closing flange 12, specifically, from the boundary between the device body 11 and the closing flange 12, and from the gap between the through holes of the closing flange 12 and the bolts 13.

[0013] The procedure for repairing a gas leak according to the embodiment will be described below with reference to Figures 2 to 7. In each figure, arrows indicate the flow of gas leaked from inside the equipment. First, as shown in Figure 2, the modified high nut 1 is attached to each bolt 13 attached to the closure flange 12 (first step). The modified high nut 1 is a modified high nut. The high nut, also known as a coupling nut, is a cylindrical fastening part with a female threaded hole. The high nut shares with the hexagonal nut the hexagonal cross section, but is longer in the axial direction than the hexagonal nut.

[0014] The high nut modification 1 is an example of a second cylindrical member capable of accommodating bolts 13, and has an enlarged diameter portion 1b at one end of the female threaded hole 1a of the high nut so that it can cover each bolt 13 attached to the closure flange 12. The enlarged diameter portion 1b is enlarged, for example, by machining to create a smooth surface. In the process shown in Figure 2, the high nut modification 1 is attached to the bolt 13 so that the enlarged side of the female threaded hole 1a contacts the surface of the closure flange 12, and the end face of the high nut modification 1 and the surface of the closure flange 12 are bonded and sealed with adhesive B.

[0015] Adhesive B may be an adhesive that cures quickly and has excellent gas resistance, such as an epoxy adhesive. Examples of epoxy adhesives that may be used include Leak Barrier (registered trademark) manufactured by Toyosho Leak Maintenance Co., Ltd. At the end of the first step, gas still leaks from the boundary between the device body 11 and the closing flange 12 and from each high nut modified product 1. However, because an escape route for the gas is secured, the end face of the high nut modified product 1 and the surface of the closing flange 12 can be bonded and sealed with adhesive B.

[0016] Next, as shown in FIG. 3, an O-ring bolt 2 is fastened one by one to each of the high-nut modified parts 1 that are in close contact with the surface of the closing flange 12 (second process). The O-ring bolt 2 is an example of a second sealing member that can be placed inside the second cylindrical member, and is a bolt with an O-ring 2c fitted to the shaft 2a so that it contacts the bolt head 2b. The O-ring 2c is an annular gasket with an O-shaped cross section. When the O-ring bolt 2 is fastened to the high-nut modified part 1, the O-ring 2c is in close contact with the end face of the high-nut modified part 1, thereby preventing gas leakage from the high-nut modified part 1. When the O-ring bolt 2 is fastened to all of the high-nut modified parts 1, the gas leakage point is limited to the boundary between the device main body 11 and the closing flange 12.

[0017] Next, as shown in FIG. 4, the kite thread 3 is wound around the boundary between the device body 11 and the closing flange 12 (third step). The kite thread 3 is a twisted cotton thread in which the gaps between the fibers serve as a gas passageway, and is an example of a string-like member having a space formed therein that serves as a gas passageway. The thickness of the kite thread 3 is, for example, in the range of 2 mm to 3 mm. The kite thread 3 is wound around the boundary at least once. The number of times the kite thread 3 is wound may be set according to the distance between the components at the boundary, and is, for example, in the range of 1 to 3 times, and preferably 1 time. Note that "the kite thread 3 is wound once" does not necessarily mean that the kite thread 3 is wound completely around the boundary, but also includes, for example, the case where the kite thread 3 is wound so that both ends of the kite thread 3 are housed inside the high nut 4.

[0018] After wrapping the kite string 3 around the boundary between the device body 11 and the closing flange 12, it is preferable to fix the kite string 3 to at least one of the device body 11 and the closing flange 12 using an adhesive to prevent the kite string 3 from shifting. The adhesive is preferably dripped at multiple locations at intervals in the circumferential direction between the kite string 3 and at least one of the device body 11 and the closing flange 12, and then allowed to harden. A jelly-like instant adhesive is preferably used as the adhesive to prevent it from dripping in unnecessary places. It is preferable to use the minimum amount of adhesive necessary to leave gaps between the fibers of the kite string 3.

[0019] Next, as shown in FIG. 5, the high nut 4 is placed above the boundary between the device main body 11 and the closing flange 12 with the end of the string 3 housed inside, and the boundary between the device main body 11 and the closing flange 12 and the high nut 4 are sealed by covering them with a sealant 6 and hardening it (fourth step). The high nut 4 is an example of a first tubular member capable of housing the string 3, such as an M8 high nut, and is configured to allow an O-ring bolt 5 to be tightened. The O-ring bolt 5 is an example of a first sealing member that can be placed inside the first tubular member, and is a bolt with an O-ring 5c ​​fitted on its shaft 5a so as to contact its head 5b. The high nut 4 is preferably placed with its female thread hole facing upward relative to the boundary between the device main body 11 and the closing flange 12.

[0020] The sealant 6 may be the same as or similar to the adhesive B used to attach the modified high-pressure nut 1 to the closing flange 12. In the fourth step, gas leaks from the female threaded hole of the high-pressure nut 4, and since an escape route for the gas is secured, the sealant 6 can provide sufficient sealing. When the boundary between the device body 11 and the closing flange 12 and the high-pressure nut 4 are sealed with the sealant 6, the high-pressure nut 4 is fixed to the boundary between the device body 11 and the closing flange 12. Gas leaking from the boundary is guided to the female threaded hole of the high-pressure nut 4 via the string 3, thereby limiting the gas leakage to a single location. When the string 3 is wrapped around the boundary between the device body 11 and the closing flange 12, both ends of the string should be long enough to extend beyond the high-pressure nut 4. After the sealant 6 has hardened, the string can be cut at the end of the high-pressure nut 4 so that it fits within the female threaded hole of the high-pressure nut 4.

[0021] Next, as shown in Figure 6, the bolt 5 with the O-ring is tightened into the high nut 4 (fifth step). This completes the primary seal of the flange joint. In steps 1 to 5, the joint is sealed in a systematic manner while limiting the gas leakage points, so a complete primary seal can be achieved without being affected by the leaking gas pressure.

[0022] Next, as shown in FIG. 7, a final seal layer 7 is provided to cover the entire repair area (sixth step). A sealant that can be hardened at room temperature and is deformable in its hardened state, such as urethane rubber, may be used for the final seal layer 7. An example of an example of urethane rubber is Devcon (registered trademark) Flexan 80P. The epoxy adhesive used as adhesive B and sealing material 6 in the previous step is difficult to deform when hardened, and cannot completely follow the shrinkage of the base material of each component of the gas circuit breaker that occurs with changes in the external temperature. Therefore, the final seal layer 7 is provided as a seal that can follow the shrinkage of the base material. The above is the flow of the gas leak repair method.

[0023] The gas leak repair structure of the embodiment is a structure for repairing gas leaks from joints of gas-filled equipment, and is constructed at the joints of gas-filled equipment by performing each step of the gas leak repair method of the embodiment.

[0024] The gas leak repair structure of the embodiment comprises a high nut modified product 1 whose end face is in close contact with the surface of a closing flange 12 to accommodate the head of a bolt 13, an O-ring-equipped bolt 2 that seals the high nut modified product 1, a string 3 wrapped around the boundary between the equipment main body 11 and the closing flange 12, a high nut 4 with a portion of the string 3 housed inside and positioned so as to contact the boundary, an O-ring-equipped bolt 5 that is positioned inside the high nut 4 and seals the high nut 4, a sealing material 6 that seals the boundary and a portion of the high nut 4, and a final sealing layer 7 that seals the high nut modified product 1, the O-ring-equipped bolts 2 and 5, the string 3, the high nut 4, the sealing material 6, a portion of the equipment main body 11, and the closing flange 12.

[0025] As described above, the gas leak repair method according to the embodiment includes the steps of wrapping a cord 3 around the boundary between the device body 11 and the closure flange 12, sealing the boundary and a portion of the high nut 4 with a sealant 6 while positioning the high nut 4 with a portion of the cord 3 housed inside so that it contacts the boundary, and positioning an O-ring-equipped bolt 5 inside the high nut 4 to seal the high nut 4.

[0026] Therefore, after hardening the sealant 6 while securing an escape route for the gas with the high nut 4, the gas leak from the high nut 4 can finally be stopped with the O-ring bolt 5, eliminating the need to recover and replenish the enclosed gas when repairing a gas leak. In addition, because the kite thread 3, high nut 4, and O-ring bolt 5 are commercially available items that are readily available at retail stores and no special tools are required for each process, the method can be widely adopted on-site and the costs associated with repairing gas leaks can be reduced.

[0027] The present invention is not limited to the above-described embodiment, and the following modifications are possible.

[0028] (Variation) In the above embodiment, O-ring bolts 2 and 5 are used to seal the high nut modified part 1 and the high nut 4, but the present invention is not limited to this. Depending on the gas pressure inside the gas-filled equipment, for example, a rubber plug, a valve, or a tube may be used as a sealing member to seal the high nut modified part 1 and the high nut 4.

[0029] In the above embodiment, a high-tension nut modified part 1 is used to accommodate the bolt 13, but the present invention is not limited to this. For example, if a large-diameter bolt that cannot accommodate the high-tension nut modified part 1 is used as the bolt 13, a tubular member 1A may be used, as shown in Figure 8, in which a bottom plate 1d with a female threaded hole 1a is provided on one side of a tubular body 1c and an opening 1e capable of accommodating the bolt 13 is provided on the other side. To obtain the tubular member 1A, for example, a gas pipe cut into the tubular body 1c is prepared, and a bottom plate 1d is welded to the end face of the cut piece so as to close the opening on one side, and a female threaded hole 1a that can vent gas is formed in the bottom plate 1d.

[0030] In the above embodiment, the string 3 is used to ensure the gas flow path, but the present invention is not limited to this. A string-like member of any material and structure may be used as long as it is a deformable member that can ensure the gas flow path and stretches like a string. For example, a twisted thread made of natural fibers other than cotton or chemical fibers may be used as the string-like member. Furthermore, string-like members include not only threads but also strings thicker than threads. Depending on the spacing between components at the boundary, for example, a cable tie, rope, string-like sponge, etc. may also be used as the string-like member.

[0031] In the above embodiment, the O-ring bolt 2 is tightened to the high nut modified product 1 in the step following the step in which the high nut modified product 1 is brought into close contact with the closing flange 12, but the present invention is not limited to this. The order of the steps in the gas leak repair method can be arbitrary; for example, the O-ring bolt 2 may be tightened to the high nut modified product 1 in the step following the step in which the high nut 4 is attached to the boundary between the device body 11 and the closing flange 12.

[0032] In the above embodiment, the end face of the high nut modified part 1 is brought into close contact with the surface of the closing flange 12 so as to cover the bolt 13, and the O-ring-equipped bolt 2 is fastened to the high nut modified part 1, but the present invention is not limited to this. For example, depending on the gas pressure of the gas-filled equipment, it is also possible to simply cover the gap between the through hole of the closing flange 12 and the bolt 13 with the sealant 6.

[0033] In the above embodiment, one high nut 4 is disposed at the boundary between the device body 11 and the closing flange 12, but the present invention is not limited to this. When the gas leakage rate is large or the flange is large, multiple high nuts 4 may be disposed at equal intervals circumferentially at the boundary, as shown in FIG. 9. For example, when three high nuts 4 are used, adjacent high nuts 4 may be disposed at intervals of 120° from each other. Inside each high nut 4, both ends of separate kite strings 3 are housed, each wrapped around the boundary so that they overlap each other. Note that, for ease of understanding, FIG. 9 illustrates only the kite string 3 whose both ends are housed in one high nut 4, and does not illustrate the kite strings 3 whose both ends are housed in the other two high nuts 4.

[0034] In the above embodiment, the repair area is entirely covered with the final sealing layer 7, but the present invention is not limited to this. If long-term sealing is not required in the gas-filled equipment, the final sealing layer 7 may be omitted.

[0035] The above-described embodiments are merely examples, and the present invention is not limited to these. Various embodiments are possible within the scope of the invention as set forth in the claims. The components described in the embodiments and modifications can be freely combined. Furthermore, inventions equivalent to the inventions set forth in the claims are also included in the present invention.

[0036] The present invention will be specifically described below with reference to examples, although the present invention is not limited to these examples.

[0037] (Example) In the examples, it was verified whether the gas leak repair method according to the embodiment can stop the leakage of N2 gas spouting from the flange joint of the test equipment.

[0038] As shown in Figure 10, the test equipment includes a metal cylinder and a pair of metal flanges detachably attached to the cylinder. High-pressure N2 gas is supplied into the cylinder from one of the flanges. The other flange was left unpacked, allowing N2 gas to leak out. Next, the internal space of the test equipment was pressurized to 0.1 MPa while the gas leak repair method according to the embodiment was carried out. The high-nut modified parts and O-ring-equipped bolts shown in Figure 11 were used, and a leak barrier was used as the adhesive and sealant for the high-nut modified parts. To minimize the amount of N2 gas released, the N2 gas pressure was set to 0.1 MPa until the leak barrier was completely cured, and then increased to 0.5 MPa (operating pressure) after the leak barrier was completely cured. As a result, the repair method according to the embodiment successfully stopped N2 gas from leaking from the flange while high-pressure N2 gas was being supplied.

[0039] Next, a pressure test was conducted in which the N2 gas pressure was gradually increased. Specifically, the N2 gas pressure was increased in 0.05 MPa increments from 0.50 MPa and held for 30 minutes, and this process was repeated until the maximum pressure reached 0.70 MPa (1.4 times the operating pressure), to check for gas leaks. The results showed that the seal did not rupture even when the N2 gas pressure was increased to 0.70 MPa. [Explanation of symbols]

[0040] 1 High nut modified 1A Cylindrical member 2,5 bolt with O-ring 3 Octopus thread 4 High Nut 6 Sealant 10 Gas Circuit Breaker 11 Device body 12 Blind flange 13 volts

Claims

1. A gas leak repair method for repairing gas leaks from joints in gas-filled equipment, comprising: a step of winding a string-like member around the boundary of the joint, the string-like member having a space formed therein to serve as a gas flow path; a step of sealing the joint and a portion of the first tubular member with a sealant in a state in which a first tubular member having a portion of the string-shaped member housed therein is placed so as to be in contact with the joint; disposing a first sealing member inside the first cylindrical member to seal the first cylindrical member; A gas leak repair method including:

2. The first tubular member is a high nut. The gas leak repair method according to claim 1.

3. the first sealing member is a bolt with an O-ring that can be tightened into the female threaded hole of the high nut; The gas leak repair method according to claim 2.

4. The joining portion is a portion where a device body and a flange of the gas filling device are joined, or a portion where flanges of the gas filling device are joined to each other. The gas leak repair method according to claim 1.

5. a step of placing a second cylindrical member so as to cover a portion of the bolt inserted into the through hole of the flange, and bringing an end surface of the second cylindrical member into close contact with a surface of the flange; and disposing a second sealing member inside the second cylindrical member to seal the second cylindrical member. The gas leak repair method according to claim 4.

6. The second cylindrical member is a modified high-nut member in which an enlarged diameter portion covering a part of the bolt inserted into the through hole of the flange is formed on one end side of the female threaded hole. The gas leak repair method according to claim 5.

7. A gas leak repair structure for repairing gas leaks from joints in gas-filled equipment, a string-like member wound around the boundary of the joint and having a space formed therein to serve as a gas flow path; a first tubular member having a portion of the string-shaped member housed therein and arranged to contact the joint; a sealing material that seals the joint and a portion of the first tubular member; a first sealing member disposed inside the first cylindrical member and sealing the first cylindrical member; A gas leak repair structure equipped with:

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