Gas leak repair method and gas leak repair structure

Abstract

To provide a gas leak repair method and gas leak repair structure that can repair gas leaks using readily available parts, even when gas is sealed inside the equipment. [Solution] The gas leak repair method includes the steps of: positioning the modified high nut 1 so as to cover a portion of the bolt 13 inserted through the through hole of the sealing flange 12, and then pressing the end face of the modified high nut 1 tightly against the surface of the sealing flange 12; and positioning the bolt 2 with an O-ring to seal the modified high nut 1 inside the modified high nut 1.

Description

Technical Field

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

Background Art

[0002] In a substation, gas circuit breakers and gas-insulated switchgear filled with sulfur hexafluoride (SF6) gas, which is a kind of greenhouse gas, are used. In these gas-filled devices, gas leakage may occur due to aging. However, due to the influence of the leaked gas pressure, it is difficult to directly repair the joint while the gas leakage continues from the gas leakage point. To solve such problems, development of a construction method for repairing gas leakage from the joint even when the gas is leaking has been carried out. For example, Patent Document 1 discloses a method in which a gas vent plug having a gas discharge port is attached after winding a gas conduction band around the joint, the joint is sealed with a sealing material together with the gas conduction band and the gas vent plug, and finally the gas discharge port of the gas vent plug is sealed with a stopper.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the construction method of Patent Document 1, since special parts such as a gas conduction band and a gas vent plug are used, it is difficult to widely spread to the field, and there is a problem that the cost associated with introduction is also high.

[0005] The present invention has been made based on such a background, and an object thereof is to provide a gas leak repair method and a gas leak repair structure that can repair gas leakage using easily available parts even when the gas is enclosed in the device. [[ID=B]]

Means for Solving the Problems

[0006] To achieve the above objective, the gas leak repair method according to the present invention is A gas leak repair method for repairing gas leaks from through holes through bolts in the flange of gas-filled equipment, The process involves positioning a cylindrical member so as to cover a portion of the bolt inserted through the through hole of the flange, and then bringing the end face of the cylindrical member into close contact with the surface of the flange. The process includes the step of placing a sealing member inside the cylindrical member to seal the cylindrical member. [Effects of the Invention]

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

[0008] [Figure 1] This diagram shows the configuration of a gas circuit breaker according to an embodiment of the present invention. [Figure 2] This figure shows the first step of a gas leak repair method according to an embodiment of the present invention. [Figure 3] This figure shows the second step of a gas leak repair method according to an embodiment of the present invention. [Figure 4] This figure shows the third step of a gas leak repair method according to an embodiment of the present invention. [Figure 5] This figure shows the fourth step of the gas leak repair method according to an embodiment of the present invention. [Figure 6] This figure shows the fifth step of the gas leak repair method according to an embodiment of the present invention. [Figure 7] This figure shows the sixth step of a gas leak repair method according to an embodiment of the present invention. [Figure 8] This figure shows the configuration of a cylindrical member according to a modified example of the present invention. [Figure 9]This 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] This figure shows the configuration of the test apparatus in the example. [Figure 11] This figure shows the appearance of the modified high nut and the bolt with O-ring in the test apparatus in the example. [Modes for carrying out the invention]

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

[0010] The gas leak repair method according to this embodiment is a method for repairing gas leaks from joints of a gas-filled device while the device is filled with gas. Joints are locations where components are joined together to prevent gas from leaking inside the gas-filled device, such as locations where a flange is joined to the device body or where flanges are joined to each other. The joints may be sealed using a gasket, or they may be sealed without a gasket. The following explanation will use the case where a gas circuit breaker is used as the gas-filled device as an example.

[0011] The gas circuit breaker according to this 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 about three times the insulating performance and about 100 times the arc extinguishing capacity of air. As shown in Figure 1, the gas circuit breaker 10 comprises a device body 11 in which insulating gas is sealed inside, a pair of closing flanges 12 that are detachably joined to both end faces of the device body 11, bolts 13 for attaching each closing flange 12 to the device body 11, and a frame 14 that supports the device body 11 from below.

[0012] The closing flange 12 is provided with a plurality of through holes through which bolts 13 can be inserted, arranged circumferentially. The equipment main body 11 is formed with female screw holes into which the bolts 13 inserted through the through holes of the closing flange 12 can be screwed, arranged circumferentially. A packing 15 is disposed between the equipment main body 11 and the closing flange 12 to prevent gas leakage. When the packing 15 deteriorates over time and loses its elasticity, gas leakage occurs from the joint portion between the equipment main body 11 and the closing flange 12, specifically, the boundary between the equipment main body 11 and the closing flange 12, and the gap between the through holes of the closing flange 12 and the bolts 13.

[0013] Hereinafter, with reference to FIGS. 2 to 7, the working procedure of the gas leakage repair method according to the embodiment will be described. In each drawing, the arrow indicates the flow of gas leaked from inside the equipment. First, as shown in FIG. 2, a high nut retrofit product 1 is brought into close contact with each bolt attached to the closing flange 12 (first step). The high nut retrofit product 1 is a part obtained by modifying a high nut. The high nut, also called a coupling nut, is a cylindrical fastening part provided with a female screw hole. The high nut is common with a hexagonal nut in having a hexagonal cross section, but has an axial length compared with the hexagonal nut.

[0014] The high nut retrofit product 1 is an example of a second cylindrical member capable of accommodating the bolt 13, and is provided with a diameter-expanded portion 1b on one end side of the female screw hole 1a of the high nut so as to cover each bolt 13 attached to the closing flange 12. The diameter-expanded portion 1b is expanded, for example, by machining to have a smooth surface. In the step of FIG. 2, the high nut retrofit product 1 is mounted on the bolt 13 such that the side where the female screw hole 1a is expanded contacts the surface of the closing flange 12, and the end face of the high nut retrofit product 1 and the surface of the closing flange 12 are adhered and sealed with an adhesive B.

[0015] As the adhesive B, an adhesive that cures rapidly and has excellent gas resistance, for example, an epoxy-based adhesive, may be used. As the epoxy-based adhesive, for example, Leak Barrier (registered trademark) manufactured by Toyo Shouhin Maintenance Co., Ltd. may be used. Note that at the time when the first step is completed, although gas is still leaking from the boundary between the equipment main body 11 and the closing flange 12 and from each modified high nut 1, since a gas escape path is secured, the end face of the modified high nut 1 and the surface of the closing flange 12 can be adhered with the adhesive B to achieve sealing.

[0016] Next, as shown in FIG. 3, one bolt 2 with an O-ring is tightened on each modified high nut 1 that is in close contact with the surface of the closing flange 12 (second step). The bolt 2 with an O-ring is an example of a second sealing member that can be disposed inside the second cylindrical member, and is a bolt in which an O-ring 2c is fitted on the shaft portion 2a so as to contact the head portion 2b of the bolt. The O-ring 2c is an annular packing having an O-shaped cross section. When the bolt 2 with an O-ring is tightened on the modified high nut 1, the O-ring 2c is in close contact with the end face of the modified high nut 1, so that gas leakage from the modified high nut 1 can be stopped. When the bolt 2 with an O-ring is tightened on all the modified high nuts 1, the gas leakage location is limited to the boundary between the equipment main body 11 and the closing flange 12.

[0017] Next, as shown in FIG. 4, a taco thread 3 is wound around the periphery of the boundary between the equipment main body 11 and the closing flange 12 (third step). The taco thread 3 is a cotton twisted thread in which the gaps between the fibers serve as gas passageways, and is an example of a string-shaped member in which a space serving as a gas flow path is formed inside. The thickness of the taco thread 3 is, for example, within the range of 2 mm to 3 mm. The taco thread 3 is wound around the periphery of the boundary at least once. The number of winding turns of the taco thread 3 may be set according to the interval between the components at the boundary. For example, it is within the range of 1 to 3 turns, and preferably 1 turn. Note that the winding of the taco thread 3 once does not only refer to the case where the taco thread 3 makes a complete turn, but also includes, for example, the case where both ends of the taco thread 3 are wound to such an extent that they are accommodated inside the high nut 4.

[0018] After wrapping the string 3 around the boundary between the equipment body 11 and the closing flange 12, it is advisable to fix the string 3 to at least one of the equipment body 11 and the closing flange 12 using adhesive to prevent the string 3 from shifting. The adhesive should be dripped at multiple points with circumferential spacing between the string 3 and at least one of the equipment body 11 and the closing flange 12, and then allowed to harden. A gel-type instant adhesive is recommended to prevent it from dripping onto unwanted areas. The minimum necessary amount of adhesive should be used to leave gaps between the fibers of the string 3.

[0019] Next, as shown in Figure 5, with the end of the string 3 housed inside, the tall nut 4 is placed above the boundary between the equipment body 11 and the closing flange 12, and the boundary between the equipment body 11 and the closing flange 12 and the tall nut 4 are covered with sealing material 6 and hardened to seal them (fourth step). The tall nut 4 is an example of a first cylindrical member capable of housing the string 3, for example, an M8 tall nut, and is configured so that an O-ring bolt 5 can be tightened. The O-ring bolt 5 is an example of a first sealing member that can be placed inside the first cylindrical member, and is a bolt in which an O-ring 5c ​​is fitted to the shaft portion 5a so as to contact the head 5b of the bolt. The tall nut 4 is preferably positioned so that the female screw hole faces upward with respect to the boundary between the equipment body 11 and the closing flange 12.

[0020] As the sealing material 6, it is preferable to use the same or similar adhesive B used to tightly attach the modified high nut 1 to the closing flange 12. In the fourth step, gas leaks from the female threaded hole of the high nut 4, and since a path for the gas to escape is secured, sufficient sealing can be achieved with the sealing material 6. When the boundary between the equipment body 11 and the closing flange 12 and the high nut 4 are sealed with the sealing material 6, the high nut 4 is fixed to the boundary between the equipment body 11 and the closing flange 12, and the gas leaking from the boundary is guided through the string 3 to the female threaded hole of the high nut 4, thus limiting the gas leak location to one place. The string 3 should be left long enough so that both ends protrude from the high nut 4 when wrapped around the boundary between the equipment body 11 and the closing flange 12, and after the sealing material 6 has hardened, it should be cut at the end face of the high nut 4 so that it fits inside the female threaded hole of the high nut 4.

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

[0022] Next, as shown in Figure 7, a final seal layer 7 is applied to cover the entire repair area (sixth step). For the final seal layer 7, a sealing material that can be cured at room temperature and is deformable in its cured state, such as urethane rubber, is preferable. For example, Devcon® Flexan 80P can be used as the urethane rubber. The epoxy adhesive used as adhesive B and sealant 6 in the above steps is difficult to deform once cured and cannot fully follow the shrinkage of the base material of each component of the gas circuit breaker due to changes in ambient temperature. Therefore, a final seal layer 7 is provided as a seal that can follow the shrinkage of the base material. The above outlines the procedure for repairing a gas leak.

[0023] The gas leak repair structure according to this embodiment is a structure for repairing gas leaks from the 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 according to this embodiment.

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

[0026] Therefore, after the sealant 6 is hardened while the gas escape route is secured with the tall nut 4, the gas leak from the tall nut 4 can finally be stopped with the O-ring bolt 5, eliminating the need to recover and replenish the sealed gas when repairing gas leaks. Furthermore, since it uses commercially available products that are easily available at retail stores, such as the string 3, tall nut 4, and O-ring bolt 5, and does not require any special tools at any of the steps, it can be widely adopted on-site and the costs associated with gas leak repairs can be reduced.

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

[0028] (modified version) In the above embodiment, bolts 2 and 5 with O-rings were used to seal the modified high nut 1 and high nut 4, but the present invention is not limited thereto. Depending on the gas pressure inside the gas-filled equipment, a rubber stopper, valve, or tube may be used as a sealing member to seal the modified high nut 1 and high nut 4.

[0029] In the above embodiment, a modified high nut 1 was 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 modified high nut 1 is used as the bolt 13, a cylindrical member 1A may be used, as shown in Figure 8, which has a bottom plate 1d with a female screw hole 1a formed on one side of the cylindrical body 1c and an opening 1e that can accommodate the bolt 13 on the other side. To obtain the cylindrical member 1A, for example, a cut gas pipe can be prepared as the cylindrical body 1c, the bottom plate 1d can be welded to the end face so as to close the opening on one side of the cut piece, and a female screw hole 1a that allows gas to be released can be formed in the bottom plate 1d.

[0030] In the above embodiment, a string 3 was used to secure the gas flow path, but the present invention is not limited thereto. Any string-like member of any material and structure may be used as long as it can secure the gas flow path and is a deformable member that extends in a string shape. For example, a twisted yarn made of natural fibers other than cotton or a chemical fiber may be used as the string-like member. Furthermore, the string-like member includes not only yarn but also strings thicker than yarn, and depending on the spacing between parts at the boundary, the string-like member may be, for example, cable tie string, rope, string-like sponge, etc.

[0031] In the above embodiment, the bolt 2 with an O-ring was tightened to the modified high nut 1 in the next step after the modified high nut 1 was tightly attached to the closing flange 12, but the present invention is not limited thereto. The order of each step in the gas leak repair method is arbitrary; for example, the bolt 2 with an O-ring may be tightened to the modified high nut 1 in the next step after the high nut 4 is attached to the boundary between the equipment body 11 and the closing flange 12.

[0032] In the above embodiment, the end face of the modified high nut 1 was pressed tightly against the surface of the closing flange 12 so as to cover the bolt 13, and the bolt 2 with an O-ring was tightened onto the modified high nut 1. However, the present invention is not limited to this. For example, depending on the gas pressure of the gas-filled equipment, it may be sufficient to simply cover the gap between the through hole of the closing flange 12 and the bolt 13 with a sealing material 6.

[0033] In the above embodiment, a single high nut 4 was placed at the boundary between the equipment body 11 and the closing flange 12, but the present invention is not limited to this. If the amount of gas leakage is large or the flange is large, multiple high nuts 4 may be arranged at equal intervals in the circumferential direction at the boundary, as shown in Figure 9. For example, when using three high nuts 4, adjacent high nuts 4 should be placed at a 120° interval from each other. Inside each high nut 4, both ends of a separate string 3, which is wound so as to overlap each other with respect to the boundary, are respectively housed. Note that in Figure 9, for ease of understanding, only the string 3 with both ends housed in one high nut 4 is shown, and the illustration of the string 3 with both ends housed in the other two high nuts 4 is omitted.

[0034] In the above embodiment, the final seal layer 7 was applied to the entire repair area, but the present invention is not limited thereto. If long-term sealing is not required in the gas-filled equipment, the final seal layer 7 may be omitted.

[0035] The embodiments described above are illustrative, and the present invention is not limited thereto. Various embodiments are possible without departing from the spirit of the invention as described in the claims. The components described in the embodiments and modifications can be freely combined. Furthermore, inventions equivalent to the invention described in the claims are also included in the present invention.

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

[0037] (Examples) In the embodiment, it was verified whether the gas leak repair method according to the embodiment could stop the leakage of N2 gas ejected from the flange joint of the test apparatus.

[0038] As shown in Figure 10, the test apparatus comprises a metal cylinder and a pair of metal flanges detachably attached to the cylinder, and is configured to supply high-pressure N2 gas into the cylinder from one flange side. The other flange was left without a packing, allowing N2 gas to leak out. Next, each step of the gas leak repair method according to the embodiment was carried out while pressurizing the internal space of the test apparatus to 0.1 MPa. The modified high nut and bolt with O-ring shown in Figure 11 were used, and Leak Barrier was used as the adhesive and sealing material for the modified high nut. In order to suppress the amount of N2 gas released, the N2 gas pressure was kept at 0.1 MPa until the Leak Barrier was fully cured, and then increased to 0.5 MPa (operating pressure) after the Leak Barrier had fully cured. As a result, the leak of N2 gas from the flange was successfully stopped while supplying high-pressure N2 gas using the repair method according to the embodiment.

[0039] Next, a pressurization test was conducted by gradually increasing the pressure of the N2 gas. Specifically, the N2 gas pressure was increased in increments of 0.05 MPa from 0.50 MPa and held for 30 minutes, repeating this process until the maximum pressure of 0.70 MPa (1.4 times the operating pressure) was reached, and it was checked whether any gas leaks occurred. As a result, the seal did not rupture even when the N2 gas pressure was increased to 0.70 MPa. [Explanation of Symbols]

[0040] 1. Modified high nut 1A Cylindrical member 2.5 bolts with O-rings 3. Twine 4. High nuts 6. Sealant 10 Gas circuit breakers 11. Main unit of the device 12 Blind flange 13 volts

Claims

1. A gas leak repair method for repairing gas leaks from through holes through bolts in the flange of gas-filled equipment, The process involves positioning a cylindrical member so as to cover a portion of the bolt inserted through the through hole of the flange, and then bringing the end face of the cylindrical member into close contact with the surface of the flange. The process includes the step of placing a sealing member inside the cylindrical member to seal the cylindrical member, Gas leak repair methods.

2. The cylindrical member is a modified high nut in which an enlarged diameter portion covering a part of the bolt inserted through the through hole of the flange is formed on one end of the female screw hole. The gas leak repair method according to claim 1.

3. The cylindrical member comprises a bottom plate having a female screw hole formed therein, and an opening on the opposite side of the bottom plate that can accommodate a portion of the bolt. The gas leak repair method according to claim 1.

4. In the above-mentioned bonding step, the surface of the flange and the end face of the cylindrical member are bonded together with an adhesive. The gas leak repair method according to claim 1.

5. A gas leak repair structure for repairing gas leaks from through holes through which bolts are inserted in the flange of a gas-filled device, A cylindrical member is positioned to cover a portion of the bolt inserted through the through hole of the flange, with its end face in close contact with the surface of the flange, A sealing member is disposed inside the cylindrical member and seals the cylindrical member, A gas leak repair structure equipped with [a specific feature].

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