Leakage prevention device, leakage prevention structure of pipe joint, and leakage prevention method

Abstract

To provide a leakage prevention device, a leakage prevention structure for a pipe joint part, and a leakage prevention method, which can suppress a decrease in sealing performance.SOLUTION: A leakage prevention device 10 includes: a first external fitting member 11 which is externally fitted to a first fluid pipe P1; a second external fitting member which is externally fitted to a second fluid pipe; a flexible pipe 14 extending in a pipe axial direction between the first external fitting member 11 and the second external fitting member and surrounding a pipe joint part at which an end part of the first fluid pipe P1 and an end part of the second fluid pipe are connected; a seal material 11b for sealing a gap between an inner peripheral face of the first external fitting member 11 and an outer peripheral face of the first fluid pipe P1; and a pressing ring 50 connected to the first external fitting member 11 via a connection structure 5 and presses the seal material 11b. The connection structure 5 is configured to maintain a gap between the first external fitting member 11 and the pressing ring 50 even when an external force in a pipe axis direction is applied which moves the first external fitting member 11 on the side away from the pipe joint part.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a leakage prevention device that prevents fluid leakage from a pipe joint, a leakage prevention structure for a pipe joint that uses the device, and a leakage prevention method that prevents fluid leakage from a pipe joint. [Background technology]

[0002] Patent Document 1 describes a leak repair expansion flexible joint, which is a leak prevention device that is attached to pipelines laid on water pipe bridges and the like. By using this leak prevention device to surround the pipe joint that connects the ends of the pipes, it is possible to prevent water from leaking outside the device even if the pipes become detached at the pipe joint. The leak prevention device described in this document has a flexible member that is extendable and contractible, and is configured to follow the expansion, contraction, and tilt of the pipeline.

[0003] Figure 14(A) shows the end of the leakage prevention device described in the above-mentioned document. An outer fitting member 92 (annular portion) fitted onto a pipe 91 constituting a pipeline is continuous with an expanded diameter portion 93 extending from a flexible member (not shown). The expanded diameter portion 93 surrounds a pipe joint portion connecting the ends of the pipes 91. The gap between the inner peripheral surface of the outer fitting member 92 and the outer peripheral surface of the pipe 91 is sealed with an annular sealing material 94. A pressing ring 95 (pressing ring) is connected to the outer fitting member 92 via a bolt 96 inserted through the flange and is configured to be able to press the sealing material 94 in response to the tightening of a nut 97. The pressing ring 95 is fixed to the pipe 91 by a fixing bolt 98. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 7-139684 Summary of the Invention [Problem to be solved by the invention]

[0005] If the pipe 91 separates from the pipe joint due to an unexpected event such as an earthquake or uneven settlement, the flexible member deforms in response to the expansion and contraction of the pipe, causing water to fill the inside of the enlarged diameter portion 93 and generating water pressure. As a result, an external force F acts in the pipe axial direction, moving the outer fitting member 92 away from the pipe joint, as shown in Figure 14(B). The inventors' investigation revealed that when the outer fitting member 92 moves due to such external force F, the gap with the pressing ring 95 decreases, causing over-compression of the sealing material 94 and uneven surface pressure, resulting in a decrease in sealing performance (watertightness).

[0006] The present disclosure has been made in consideration of the above-mentioned situation, and its purpose is to provide a leakage prevention device, a leakage prevention structure for a pipe joint portion, and a leakage prevention method that can suppress a decrease in sealing performance. [Means for solving the problem]

[0007] The leakage prevention device of the present disclosure comprises a first outer fitting member fitted onto a first fluid pipe, a second outer fitting member fitted onto a second fluid pipe, an expandable tube extending in the pipe axis direction between the first outer fitting member and the second outer fitting member and surrounding a pipe joint portion where an end of the first fluid pipe and an end of the second fluid pipe are connected, a sealing material that seals the gap between the inner surface of the first outer fitting member and the outer surface of the first fluid pipe, and a pressure ring that is connected to the first outer fitting member via a connecting structure and presses the sealing material, and the connecting structure is configured so that the distance between the first outer fitting member and the pressure ring is maintained even when an external force in the pipe axis direction is applied to move the first outer fitting member away from the pipe joint portion.

[0008] The leakage prevention structure for a pipe joint of the present disclosure is one in which the above-mentioned leakage prevention device is attached to a pipe joint to which an end of the first fluid pipe and an end of the second fluid pipe are connected.

[0009] The leakage prevention method disclosed herein comprises the steps of fitting a first outer fitting member onto a first fluid pipe, fitting a second outer fitting member onto a second fluid pipe, joining one end of an expandable pipe that extends in the pipe axis direction between the first outer fitting member and the second outer fitting member and surrounds a pipe joint portion where an end of the first fluid pipe and an end of the second fluid pipe are connected to the first outer fitting member and joining the other end of the expandable pipe to the second outer fitting member, and connecting a pressure ring to the first outer fitting member via a connecting structure and pressing a sealing material attached to a gap between the inner surface of the first outer fitting member and the outer surface of the first fluid pipe with the pressure ring, wherein the connecting structure is configured to maintain the distance between the first outer fitting member and the pressure ring even when an external force in the pipe axis direction is applied that moves the first outer fitting member away from the pipe joint portion. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a side view showing a leakage prevention device according to a first embodiment; [Figure 2] A front view of the leak prevention device in Figure 1 as seen from the pipe axis direction. [Figure 3] Cross-sectional view showing the periphery of the pipe joint in Figure 1 [Figure 4] FIG. 2 is a cross-sectional view showing the periphery of the first outer fitting member of FIG. 1. [Figure 5] A cross-sectional view showing the pipe of Figure 1 in an extended state. [Figure 6] Cross-sectional view showing the eccentricity of the pipe in Figure 1 [Figure 7] A side view showing the process of installing the leakage prevention device [Figure 8] A side view showing the process of installing the leakage prevention device [Figure 9] Cross-sectional view showing the process of installing the leakage prevention device [Figure 10] 10 is a cross-sectional view showing a leakage prevention device according to a second embodiment; [Figure 11] 10 is a cross-sectional view showing a leakage prevention device according to a third embodiment. [Figure 12] 10 is a cross-sectional view showing a leakage prevention device according to a fourth embodiment. [Figure 13](A) A front view of the spacer shown in FIG. 12 and (B) a spacer according to a modification thereof. [Figure 14] 1 is a cross-sectional view showing an end of a leak prevention device according to the prior art; DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment of the leakage prevention device and the leakage prevention structure for a pipe joint according to the present disclosure will be described.

[0012] [First embodiment] First, a first embodiment will be described with reference to Figures 1 to 9. The leakage prevention device 10 shown in Figures 1 to 3 is attached to a pipe joint JT that connects an end of a pipe P1 serving as a first fluid pipe and an end of a pipe P2 serving as a second fluid pipe. In this embodiment, an example is shown in which a pipeline including pipes P1 and P2 is laid on an aqueduct bridge (for example, an independent aqueduct bridge or an attached aqueduct bridge). However, this is not limited to this, and the pipeline may be laid indoors or outdoors of a building, or may be buried underground. Pipes P1 and P2 are each steel pipes with a nominal diameter of 900 that are used as water pipes, but specifications such as pipe dimensions can be changed as appropriate depending on the conditions of use.

[0013] If the pipes P1 and P2 at the pipe joint JT become separated due to an unforeseen event such as an earthquake or differential settlement, fluid will leak from the gap and leak to the outside. To prevent such fluid leakage (water leakage in this embodiment), a leakage prevention device 10 is attached to the pipe joint JT. The leakage prevention device 10 is configured to hermetically surround the periphery of the pipe joint JT, which may be a leak point, and prevent water leakage to the outside. Therefore, an enclosed space is formed around the pipe joint JT to which the leakage prevention device 10 is attached.

[0014] As shown in Figure 3, in the pipe joint JT, pipes P1 and P2 are connected via a collar 40. The collar 40 is also called a sleeve joint. The collar 40 has a cylindrical body 41 arranged across the pair of pipes P1 and P2, and annular seals 42 attached to both ends of the body 41. The seals 42 seal the gaps between the inner circumferential surface of the collar 40 and the outer circumferential surfaces of the pipes P1 and P2. The seal 42 is made of an elastic material such as rubber, and the same is true for the other seals 11b and 12b described below.

[0015] 1 to 4, the leakage prevention device 10 includes an outer fitting member 11 (first outer fitting member) fitted onto the pipe P1, an outer fitting member 12 (second outer fitting member) fitted onto the pipe P2, a flexible pipe 14 as an expandable pipe extending in the pipe axial direction between the outer fitting members 11 and 12 and surrounding a pipe joint JT where the end of the pipe P1 and the end of the pipe P2 are connected, a sealant 11b that seals the gap between the inner circumferential surface of the outer fitting member 11 and the outer circumferential surface of the pipe P1, and a pressure ring 50 connected to the outer fitting member 11 via a connecting structure 5 and that presses the sealant 11b. Hereinafter, the side opposite the pressing direction of the sealant 11b by the pressure ring 50 (the left side in FIG. 4) will be referred to as the "one pipe axial direction side AD1," and the side in the same direction as the pressing direction of the sealant 11b (the right side in FIG. 4) will be referred to as the "other pipe axial direction side AD2."

[0016] The outer fitting member 11 has a retaining portion 11a that retains the sealing material 11b, and an extension body 11c that extends in the pipe radial direction. The retaining portion 11a is formed as a tubular body with an inner diameter that allows it to fit onto the pipe P1. In this embodiment, the outer fitting member 11 (the retaining portion 11a) has a female thread portion 11e into which a connecting bolt 52, which will be described later, is threaded. Therefore, the retaining portion 11a itself functions as a flange for connecting the connecting bolt 52. The thickness of the retaining portion 11a in the pipe radial direction is set to be large enough to form the female thread portion 11e. The retaining portion 11a and the extension body 11c are integrated and are made of a metal material such as stainless steel.

[0017] As described above, in this embodiment, the retaining portion 11a is formed integrally with the extension body 11c and also serves as a flange to which the connecting bolt 52 is attached. Therefore, the gap between the extension body 11c and the flange is substantially zero, and the device is configured compactly. This also applies to the third and fourth embodiments described below. As a modified example, the thickness of the extension body 11c can be increased partially or entirely, so that the extension body 11c also serves as a flange.

[0018] The outer fitting member 12 has a holding portion 12a that holds the sealing material 12b and an extension 12c that extends in the pipe diameter direction. The configuration of the outer fitting member 11 described in this specification can be similarly applied to the outer fitting member 12, so a detailed description of the outer fitting member 12 will be omitted.

[0019] The leakage prevention device 10 of this embodiment includes a tie rod 13 inserted through rod holes formed in the extension body 11c of the outer fitting member 11 and the extension body 12c of the outer fitting member 12. The tie rod 13 has a restricting member 15 that restricts the relative movement of the tie rod 13 with respect to the extension bodies 11c, 12c. The restricting member 15 is formed by a nut threaded onto the male thread portion of the tie rod 13, and may also include a spacer and a washer. The position of the restricting member 15 on the tie rod 13 can be set appropriately taking into account the amount of relative movement of the tie rod 13 with respect to the extension bodies 11c, 12c.

[0020] One end of the flexible pipe 14 is joined to the extension body 11c, and the other end is joined to the extension body 12c. The flexible pipe 14 is an expandable and flexible pipe that can follow the expansion and contraction and eccentricity of the pipeline, so if the pipes P1 and P2 are separated at the pipe joint JT, the leakage prevention device 10 can deform accordingly. In this embodiment, the flexible pipe 14 is made of a metal material (including alloys) such as stainless steel, carbon steel, iron, or copper. Among these, stainless steel is particularly preferred because of its strength, corrosion resistance, and ease of workability when formed into a corrugated pipe.

[0021] The flexible pipe 14 is formed of a corrugated pipe extending in a corrugated pattern along the pipe axis direction. More specifically, the flexible pipe 14 is formed of a bellows pipe having a bellows structure. In this embodiment, the flexible pipe 14, which is a bellows pipe, has a bellows structure in which low and high mountain shapes alternate. This configuration reduces interference during deformation and can absorb large displacements. However, this is not limited to this, and a bellows structure in which mountain shapes of uniform height are repeated may also be used. Furthermore, the corrugated pipe is not limited to a bellows pipe formed with alternating concave and convex shapes along the pipe axis direction, but a corrugated pipe formed with concave and convex shapes spirally along the pipe axis direction may also be used.

[0022] From the viewpoint of improving workability when joining to the extension body 11c, it is preferable that the end of the flexible pipe 14 extends straight along the pipe axis direction. In this embodiment, the end of the flexible pipe 14 joined to the extension body 11c is formed by a metal extension member 14E, which is a separate member from the main body formed as a corrugated pipe. The extension member 14E and the main body are joined by welding, but mechanical joining using bolts, rivets, etc. is also acceptable. The type of joint used when joining is not limited to a lap joint, and may be a butt joint, etc.

[0023] As shown enlarged in FIG. 4, the pressure ring 50 includes a pressing portion 51 that presses the sealing material 11b, a main body portion 53 that is disposed away from the outer fitting member 11 in the pipe axis direction, and a connecting bolt 52 that connects the main body portion 53 to the outer fitting member 11. A through hole 53h is formed in the main body portion 53 as a clearance hole. The connecting bolt 52 inserted into the through hole 53h is threaded into the female thread portion 11e. Thus, the main body portion 53 functions as a flange for connecting the connecting bolt 52. A nut 57 located on one side AD1 of the main body portion 53 in the pipe axis direction and a nut 58 located on the other side AD2 of the main body portion 53 in the pipe axis direction are attached to the connecting bolt 52.

[0024] The pressure ring 50 is provided with a separation prevention mechanism that prevents the pipe P1 from separating from the pressure ring 50. In this embodiment, the separation prevention mechanism is integrally provided on the pressure ring 50. The pressure bolt 59 is threaded into a threaded hole provided in a portion that protrudes from the main body 53 toward one side AD1 in the pipe axial direction. A claw is formed on the tip of the pressure bolt 59 on the inner side in the pipe radial direction so that it can be engaged with the outer surface of the pipe P1. As shown in Figures 1 and 2, the pressure bolts 59 are arranged at multiple locations around the pipe. The separation prevention effect is achieved by having the pressure bolt 59 protrude inward in the pipe radial direction and having the claw at its tip firmly engage with the outer surface of the pipe P1.

[0025] The pressure ring 50 is configured so that, when the nut 57 is rotated, the pressing portion 51 approaches the outer fitting member 11 and presses the sealing material 11b, thereby sealing the gap between the outer fitting member 11 and the pipe P1. Fig. 4 shows a state in which the nut 58 is in contact with the main body 53 and the pressing bolt 59 is engaged with the outer peripheral surface of the pipe P1, but as will be described later, the nut 58 is tightened and the pressing bolt 59 is engaged with the outer peripheral surface of the pipe P1 after the pressure ring 50 is brought close to the outer fitting member 11 and the gap is sealed with the sealing material 11b.

[0026] 1 to 4 show the initial state when the leakage prevention device 10 is attached to the pipe joint portion JT. The collar 40 is not in contact with either the outer fitting member 11 or the outer fitting member 12, but this is not limited to this. The flexible pipe 14 is in a natural state in which no external force is acting to expand or contract it. As shown in FIG. 5, if the pipes P1 and P2 at the pipe joint portion JT are detached from the collar 40 due to an unexpected event, the pipe line expands, widening the gap between the outer fitting member 11 and the outer fitting member 12, and the flexible pipe 14 expands accordingly. The relative movement of the tie rod 13 with respect to the extension bodies 11c and 12c, and the resulting relative movement between the outer fitting member 11 and the outer fitting member 12, are restricted by the restricting member 15. Therefore, the amount of expansion (extension) of the flexible pipe 14 can be adjusted by the tie rod 13.

[0027] According to this leakage prevention device 10, water leaking from gaps created by the extension of the pipeline can be contained in a sealed space within the device, preventing leakage to the outside. The leakage prevention device 10 is provided with a valve 9 for discharging water from within the device. As shown in FIG. 6, if the pipeline becomes eccentric (misaligned between pipes P1 and P2) after extension, the flexible pipe 14 deforms accordingly. In this way, leakage of fluid can be prevented by following the expansion / contraction and eccentricity of the pipeline. Moreover, since the flexible pipe 14 is made of metal in this embodiment, it has superior strength compared to flexible members made of rubber or synthetic resin, and is highly practical, especially since it can withstand eccentricity even when the pipeline becomes eccentric.

[0028] As the flexible pipe 14 deforms in response to the expansion and contraction of the pipe as described above, water fills the interior of the flexible pipe 14, generating water pressure. This causes an axial external force F (see FIG. 5 ) to act on the outer fitting member 11, moving it toward one axial side AD1 (the side away from the pipe joint JT). When this external force F causes the outer fitting member 11 to move relative to the pipe P1, the gap between the outer fitting member 11 and the pressure ring 50 decreases, causing overcompression of the sealing material 11b and uneven surface pressure, potentially resulting in a deterioration in sealing performance (watertightness) (see FIG. 14 ). In light of this, in this embodiment, the connecting structure 5 is configured to maintain the gap between the outer fitting member 11 and the pressure ring 50 even when the external force F is applied. This effectively prevents a change in the compression state of the sealing material 11b, thereby preventing a deterioration in sealing performance.

[0029] As can be seen from Fig. 4, the connecting structure 5 is configured to transmit a force acting on the outer fitting member 11 by an external force F to the main body 53 via the connecting bolt 52. In this embodiment, the force acting on the outer fitting member 11 in the pipe axis direction by the external force F is transmitted to the connecting bolt 52 threaded into the female thread portion 11e, and then transmitted to the main body 53 from a nut 58 attached to the connecting bolt 52. The pressure ring 50 has a restricting member that restricts the relative movement of the connecting bolt 52 with respect to the main body 53, and in this embodiment, this corresponds to the nut 58. By restricting the relative movement of the connecting bolt 52 with respect to the main body 53, the distance between the outer fitting member 11 and the pressure ring 50 is maintained even when the external force F is applied.

[0030] [Leak prevention method] As a leakage prevention method, an example of a process for attaching leakage prevention device 10 to an existing pipeline will be described. As shown in Figures 7 to 9, this leakage prevention method includes the steps of fitting outer fitting member 11 onto pipe P1, fitting outer fitting member 12 onto pipe P2, joining one end of flexible pipe 14, which serves as an expandable pipe extending in the pipe axial direction between outer fitting member 11 and outer fitting member 12 and surrounding pipe joint JT, to outer fitting member 11 and joining the other end of flexible pipe 14 to outer fitting member 12, and connecting pressure ring 50 to outer fitting member 11 via connecting structure 5 and pressing sealant 11b attached to the gap between the inner circumferential surface of outer fitting member 11 and the outer circumferential surface of pipe P1 with pressure ring 50. A more specific example will be described below.

[0031] First, the outer fitting member 11 is attached to the pipe P1. Specifically, as shown in Figures 7(A) to 7(C), after the semicircular arc-shaped segment 11X is placed in a predetermined position in the pipeline, the similarly semicircular arc-shaped segment 11Y is set to form a ring shape, and the segments 11X and 11Y are joined by welding at the joint 11Z where their end faces meet. A jig is used as necessary to position and center the segments 11X and 11Y. In Figure 7(C), fasteners (bolts and nuts) are attached across the joint 11Z to temporarily secure the segments 11X and 11Y, but these are removed after the joint 11Z is joined (see Figures 1 and 2). The outer fitting member 12 is attached to the pipe P2 in the same manner as the outer fitting member 11.

[0032] Next, the flexible pipe 14 is attached so as to surround the pipe joint portion JT. Specifically, as shown in Figures 8(A) to 8(C), after the semicircular arc-shaped segment 14X is placed in a predetermined position in the pipeline, the similarly semicircular arc-shaped segment 14Y is set in place to form a ring shape. At this stage, the joint 14Z where the end faces of the segments 14X and 14Y butt against each other has not yet been joined. Since the flexible pipe 14 before the multiple segments 14X and 14Y are joined to each other is placed between the outer fitting member 11 and the outer fitting member 12, it is preferable to temporarily fix them by tack welding or the like.

[0033] Next, gas leakage tape or yarn is used to seal the gap between the inner circumferential surface of the outer fitting member 11 and the outer circumferential surface of the pipe P1, the gap between the inner circumferential surface of the outer fitting member 12 and the outer circumferential surface of the pipe P2, and the joint 14Z, and then a shielding gas is injected into the internal space of the flexible pipe 14. The shielding gas is an inert gas required for welding the joint 14Z. In this embodiment, the shielding gas is injected through a communication hole 7 (see FIG. 4) provided in the extension member 14E of the flexible pipe 14. After the injection of the shielding gas is completed, a plug 8 (see FIG. 4) is attached to close the communication hole 7. The communication hole 7 can also be provided in the outer fitting members 11 and 12.

[0034] After the shielding gas is injected, the multiple divided pieces 14X, 14Y are welded together and integrated from the outside of the flexible pipe 14. At this time, a welding torch is brought close to the joint 14Z from the outside of the flexible pipe 14. Because the thickness of the flexible pipe 14 is relatively small, when the welding torch is brought close, the heat of the arc melts not only the outer circumferential surface of the joint 14Z but also the inner circumferential surface. The outer circumferential surface of the joint 14Z is covered with the shielding gas supplied from the welding torch, and the inner circumferential surface of the joint 14Z is covered with the shielding gas that has been injected into the flexible pipe 14 in advance. This ensures appropriate welding quality for the joint 14Z.

[0035] After joining the joint 14Z, one end of the flexible pipe 14 is joined to the extension body 11c by welding, and the other end is joined to the extension body 12c by welding. In this way, the flexible pipe 14 is formed by joining together by welding a plurality of (two in this embodiment) segmented pieces 14X, 14Y that are divided in the circumferential direction of the pipe, and has a segmented structure that can be fitted onto an existing pipeline. In this embodiment, an example is shown in which the outer fitting member 11, the outer fitting member 12, and the flexible pipe 14 are each composed of two segmented pieces, but the number of segmented pieces that make them up is not particularly limited.

[0036] In this embodiment, the outer fitting member 11, the outer fitting member 12, and the flexible pipe 14 are attached in this order, but this is not limited to this. For example, the flexible pipe 14 may be attached first, and then the outer fitting member 11 and the outer fitting member 12 may be positioned so that the flexible pipe 14 is sandwiched between them, and then they may be joined by welding. The welding procedure is not limited to the above. For example, the segments 11X and 11Y may be joined to the segments 14X and 14Y, respectively, by welding in advance, and the same applies to the segments that make up the outer fitting member 12.

[0037] Next, as shown in FIG. 9(A), the divided pressure ring 50 is fitted onto the pipe P1, and the sealing material 11b is arranged in an annular shape along the outer surface of the pipe P1. The portion of the pressure ring 50, including the pressing portion 51 and the main body portion 53, consists of multiple semicircular arc-shaped segments. These segments are combined to form an annular ring, and then the end faces of the segments are butted together and welded together. A jig 80 is fixed to the outer surface of the pipe P1 by welding. The jig 80 is left in place, but may be removed after being used to position and center the outer fitting member 11. A connecting bolt 52 with a nut 58 attached is threaded into the female thread portion 11e of the outer fitting member 11. A double-threaded bolt (or stud bolt or stud bolt) is preferably used as the connecting bolt 52.

[0038] 9(B), a nut 57 is attached to the connecting bolt 52 inserted through the through-hole 53h of the main body 53, and the main body 53 is moved closer to the outer fitting member 11 by rotating the nut 57. Meanwhile, the nut 58 is moved toward the other side AD2 in the pipe axial direction so as not to come into contact with the main body 53. The tip of the pressing bolt 59 has not yet engaged with the outer surface of the pipe P1. The sealing material 11b is pressed along the pipe axial direction by the pressing portion 51, which moves together with the main body 53, to seal the gap between the inner surface of the outer fitting member 11 and the outer surface of the pipe P1. By controlling the tightening torque of the nut 57, the sealing material 11b can be compressed appropriately while maintaining uniform surface pressure, thereby achieving the desired sealing performance.

[0039] 9(C), the nuts 58 are brought into contact with the main body 53, restricting the movement of the connecting bolts 52 relative to the main body 53. This allows the connecting structure 5 to maintain the distance between the outer fitting member 11 and the pressure ring 50 even when an external force F is applied. Nuts 58 do not need to be attached to all connecting bolts 52 around the circumference of the pipe; they may be attached at appropriate intervals, for example, at four locations around the circumference of the pipe. After connecting the pressure ring 50 to the outer fitting member 11, the pressure bolts 59 are operated to lock their tips onto the outer peripheral surface of the pipe P1.

[0040] As described above, the seal material 11b attached to the outer fitting member 11 is sealed with the press ring 50. In this embodiment, the seal material 12b attached to the outer fitting member 12 is sealed with the press ring 50 in the same manner as the outer fitting member 11. Therefore, the connection structure connecting the outer fitting member 12 to the press ring 50 is configured to maintain the distance between the outer fitting member 12 and the press ring 50 even when an external force in the pipe axial direction acts to move the outer fitting member 12 away from the pipe joint portion JT, and as a result, deterioration in the sealing performance of the outer fitting member 12 is also suppressed. Then, by attaching the tie rod 13 to the outer fitting members 11, 12, the leakage prevention structure for the pipe joint portion JT shown in Figures 1 to 4 is obtained.

[0041] After the leak prevention device 10 is installed in the pipeline, it is desirable to conduct a test at the construction site to confirm the quality of the welded parts. One possible test is to fill the flexible pipe 14 with water and perform a water pressure test. However, depending on the environment of the construction site, there is a risk that drainage after the test will be hindered. In such cases, instead of a water pressure test, an airtight test can be performed using a shielding gas injected into the flexible pipe 14. After the test, the necessary areas are painted and the construction is completed.

[0042] [Second embodiment] Next, a second embodiment will be described with reference to Fig. 10. The second embodiment can be configured similarly to the first embodiment except for the configuration described below, so a description of the commonalities will be omitted and differences will be mainly described. The same reference numerals will be used to designate components already described in the first embodiment, and duplicated descriptions will be omitted.

[0043] The leakage prevention device 10 shown in Fig. 10 includes an outer fitting member 11, an outer fitting member 12 (not shown in Fig. 10), a flexible pipe 14 which is an expandable pipe, a sealing material 11b, and a press ring 50. As in the first embodiment, the connecting structure 5 is configured so that the distance between the outer fitting member 11 and the press ring 50 is maintained even when an external force F (see Fig. 5) in the pipe axial direction acts to move the outer fitting member 11 away from the pipe joint part JT (not shown in Fig. 10).

[0044] The outer fitting member 11 has a retaining portion 11a that retains the sealing material 11b and an extension body 11c that extends in the pipe radial direction. In this embodiment, the outer fitting member 11 further has a flange 11d that extends radially outward from the retaining portion 11a. A through hole 11f is formed in the flange 11d as a blind hole, and a connecting bolt 52 is inserted through the through hole. In this example, the connecting bolt 52 is a T-head bolt, and its head is located on the other side AD2 of the flange 11d in the pipe axial direction. The through hole 11f is formed in a U-groove shape with a notch cut out on the outer side in the pipe radial direction so that the connecting bolt 52 can be inserted into the flange 11d from the outer side in the pipe radial direction.

[0045] A through hole 53h is formed in the main body 53 of the press ring 50, and a connecting bolt 52 inserted into the through hole 53h is fixed to the flange 11d of the outer fitting member 11. Attached to the connecting bolt 52 are a nut 57 located on one side AD1 in the pipe axis direction of the main body 53, a nut 58 located on the other side AD2 in the pipe axis direction of the main body 53, and a nut 56 located on one side AD1 in the pipe axis direction of the flange 11d. The outer fitting member 11 has a first restricting member that restricts relative movement of the connecting bolt 52 with respect to the outer fitting member 11, and in this embodiment, the nut 56 corresponds to this first restricting member.

[0046] 10 , the connecting structure 5 is configured to transmit a force acting on the outer fitting member 11 by an external force F to the main body 53 via the connecting bolt 52. In this embodiment, the force acting on the outer fitting member 11 in the pipe axis direction by the external force F is transmitted from the flange 11d to the connecting bolt 52 via the nut 56, and then transmitted to the main body 53 from a nut 58 attached to the connecting bolt 52. The press ring 50 has a second restricting member that restricts the relative movement of the connecting bolt 52 with respect to the main body 53, and in this embodiment, this corresponds to the nut 58. By restricting the relative movement of the connecting bolt 52 with respect to the main body 53, the distance between the outer fitting member 11 and the press ring 50 is maintained even when the external force F is applied.

[0047] Although not shown in the figures, in the second embodiment as well as in the third and fourth embodiments described below, a separation prevention mechanism using a pressure bolt 59 is provided on the press ring 50. Note that the separation prevention mechanism is not limited to a mechanism using a pressure bolt 59. Therefore, for example, it may be a mechanism including a claw member that exerts a wedge action when an external force (separation force) acts in the pipe axial direction to separate the pipe P1 from the outer fitting member 11, and a pressing member that presses the claw member, or a mechanism in which a hook engages with the press ring 50 or the outer fitting member 11 when a separation force is applied, thereby exerting a separation prevention effect. In addition to or instead of the press ring 50, a separation prevention mechanism may be provided on the outer fitting member 11.

[0048] [Third embodiment] Next, a third embodiment will be described with reference to Fig. 11. The third embodiment can be configured similarly to the first embodiment except for the configuration described below, so a description of the commonalities will be omitted and differences will be mainly described. The same reference numerals will be used to designate components already described in the first embodiment, and duplicated descriptions will be omitted.

[0049] The leakage prevention device 10 shown in Fig. 11 includes an outer fitting member 11, an outer fitting member 12 (not shown in Fig. 11), a flexible pipe 14 which is an expandable pipe, a sealing material 11b, and a press ring 50. As in the first embodiment, the connecting structure 5 is configured so that the distance between the outer fitting member 11 and the press ring 50 is maintained even when an external force F (see Fig. 5) in the pipe axial direction acts to move the outer fitting member 11 away from the pipe joint part JT (not shown in Fig. 11).

[0050] The outer fitting member 11 has a retaining portion 11a that retains the sealing material 11b and an extension 11c that extends radially outward from the pipe. Figures 11(A) and 11(B) show cross sections at different circumferential positions of the pipe. As shown in Figure 11(A), the outer fitting member 11 (the retaining portion 11a) has a female threaded portion 11e into which a connecting bolt 52 inserted through a through hole 53h is threaded. This is the same structure as in the first embodiment. However, unlike the first embodiment, the connecting bolt 52 does not have a restricting member (nut 58 in Figure 4) attached to it that restricts relative movement of the connecting bolt 52 with respect to the main body 53.

[0051] In the cross section shown in Figure 11(A), a connecting bolt 52 is attached to a main body 53, while in the cross section shown in Figure 11(B), an abutting bolt 54 is attached to the main body 53. Therefore, the pressure ring 50 includes a pressing portion 51 that presses the sealing material 11b, a main body 53 that is arranged away from the outer fitting member 11 in the pipe axial direction, a connecting bolt 52 that connects the main body 53 to the outer fitting member 11, and an abutting bolt 54 that abuts against the outer fitting member 11. A headed bolt is used as the abutting bolt 54, but this is not limited to this. The pressure ring 50 has a female thread portion 53s into which the abutting bolt 54 is threaded. The female thread portion 53s is formed as a through-hole in the main body 53.

[0052] In the cross section shown in FIG. 11(B), the outer fitting member 11 has a pressure-receiving surface 55 that receives the tip of the abutment bolt 54. As can be seen from FIG. 11(B), the connecting structure 5 is configured to transmit a force acting on the outer fitting member 11 by an external force F to the main body portion 53 via the abutment bolt 54. In this embodiment, the force acting on the outer fitting member 11 in the pipe axis direction by the external force F is transmitted from the pressure-receiving surface 55 of the outer fitting member 11 to the abutment bolt 54, and then transmitted to the main body portion 53 at the female thread portion 53s into which the abutment bolt 54 is threaded. By restricting the relative movement of the abutment bolt 54 with respect to the main body portion 53, the distance between the outer fitting member 11 and the pressure ring 50 is maintained even when the external force F is applied.

[0053] In the present embodiment, an example has been shown in which the pressure ring 50 has the female thread portion 53s into which the abutment bolt 54 is threaded, but instead, the pressure ring 50 may have a restricting member that restricts the relative movement of the abutment bolt 54 with respect to the main body portion 53. In that case, similar to the nut 58 employed in the first and second embodiments, it is conceivable to insert the abutment bolt 54 into a through-hole that serves as a clearance hole formed in the main body portion 53, and attach a nut that serves as a restricting member that is located on the other side AD2 of the main body portion 53 in the pipe axis direction to the abutment bolt 54.

[0054] [Fourth embodiment] Next, a fourth embodiment will be described with reference to Figures 12 and 13. The fourth embodiment can be configured similarly to the first embodiment except for the configuration described below, so a description of the commonalities will be omitted and differences will be mainly described. The same reference numerals will be used to designate components already described in the first embodiment, and duplicated descriptions will be omitted.

[0055] The leakage prevention device 10 shown in Fig. 12 includes an outer fitting member 11, an outer fitting member 12 (not shown in Fig. 12), a flexible pipe 14 which is an expandable pipe, a sealing material 11b, and a press ring 50. As in the first embodiment, the connecting structure 5 is configured so that the distance between the outer fitting member 11 and the press ring 50 is maintained even when an external force F (see Fig. 5) in the pipe axial direction acts to move the outer fitting member 11 away from the pipe joint part JT (not shown in Fig. 12).

[0056] In this embodiment, a spacer 6 is disposed between the outer fitting member 11 and the main body 53 so as to fill the gap therebetween. The spacer 6 is a plate-like member formed of a rigid material such as steel. FIG. 13(A) is a front view of the spacer 6 as viewed from one side AD in the pipe axial direction. As shown in FIG. 13(A), the spacer 6 is disposed so as to cover the connecting bolt 52. The spacer 6 is formed with a notched groove 61 that opens toward the inside in the pipe radial direction and through which the connecting bolt 52 is inserted. The shape and location of the spacer 6 are not limited thereto; for example, a quadrilateral spacer 6 as shown in FIG. 13(B) may be used and disposed between the connecting bolts 52.

[0057] In the fourth embodiment, by fitting a spacer 6 between the outer fitting member 11 and the main body 53, it is possible to configure a connecting structure 5 that maintains the distance between the outer fitting member 11 and the press ring 50. Therefore, unlike the first to third embodiments, this can be configured even after the press ring 50 is connected to the outer fitting member 11, and therefore it can be applied to existing leakage prevention devices. After the spacer 6 is placed, it is preferable to prevent it from falling off by fixing it with adhesive tape or by wrapping a strip-shaped object such as a rubber belt or metal band around the outer periphery.

[0058] [Other variations] In the first to fourth embodiments, the pipe joint JT to which the leakage prevention device 10 is attached has a structure in which the pipe P1 and the pipe P2 are connected via a collar 40, but the present invention is not limited to this. For example, the pipes P1 and P2 may be connected by fitting a spigot formed on one end of each pipe P1 into a socket formed on the other end of each pipe P2. When the pipes P1 and P2 are ductile cast iron pipes, K-joints, T-joints, and the like are known as pipe joints having such a structure.

[0059] In the first to fourth embodiments, an example is shown in which the leakage prevention device 10 is provided with a tie rod 13 that is inserted into a rod hole formed in each of the extension body 11c and the extension body 12c, but this is not limited to this, and the tie rod 13 can also be omitted.

[0060] In the first to fourth embodiments, an example was shown in which the expandable tube was a metal flexible tube 14, but this is not limited thereto, and any tube formed to be expandable and contractible along the tube axis direction can be used without any particular restrictions. Therefore, for example, the expandable tube may be provided with a first cylindrical body, a second cylindrical body inserted into the first cylindrical body, and an annular sealing material that seals the gap between them, and is configured so that the first cylindrical body and the second cylindrical body are movable relative to each other along the tube axis direction.

[0061] In the first to fourth embodiments, examples have been shown in which the fluid pipes are water pipes, but the present invention is not limited to this and may be a fluid pipe used for a liquid other than water, a gas, or a gas-liquid mixture.

[0062] It will be understood by those skilled in the art that the above-described embodiments are examples of the following aspects.

[0063] [1] A leakage prevention device according to the present disclosure includes a first outer fitting member fitted onto a first fluid pipe, a second outer fitting member fitted onto a second fluid pipe, an expandable tube extending in a pipe axial direction between the first outer fitting member and the second outer fitting member and surrounding a pipe joint portion where an end of the first fluid pipe and an end of the second fluid pipe are connected, a sealant that seals a gap between an inner circumferential surface of the first outer fitting member and an outer circumferential surface of the first fluid pipe, and a press ring that is connected to the first outer fitting member via a connecting structure and presses the sealant. The connecting structure is configured so that the distance between the first outer fitting member and the press ring is maintained even when an external force in the pipe axial direction acts to move the first outer fitting member away from the pipe joint portion.

[0064] With this configuration, even if an external force in the pipe axial direction occurs due to an unforeseen event that moves the first outer fitting member away from the pipe joint portion, the distance between the first outer fitting member and the pressure ring is maintained and the compression state of the sealing material does not change substantially, thereby preventing a decrease in sealing performance.

[0065] [2] In the leakage prevention device of [1] above, the pressure ring may include a pressing portion that presses the sealing material, a main body portion that is positioned away from the first outer fitting member in the pipe axis direction, and a connecting bolt that connects the main body portion to the first outer fitting member, and the connecting structure may be configured to transmit the force acting on the first outer fitting member by the external force to the main body portion via the connecting bolt.

[0066] [3] In the leakage prevention device of [1] or [2] above, the pressure ring may comprise a pressing portion that presses the sealing material, a main body portion that is positioned away from the first outer fitting member in the pipe axis direction, and a connecting bolt that connects the main body portion to the first outer fitting member, wherein the first outer fitting member has a female thread portion into which the connecting bolt is threaded, and the pressure ring may comprise a regulating member that regulates the relative movement of the connecting bolt with respect to the main body portion.

[0067] [4] In any one of the leakage prevention devices [1] to [3] above, the pressure ring may include a pressing portion that presses the sealing material, a main body portion that is positioned away from the first outer fitting member in the pipe axis direction, and a connecting bolt that connects the main body portion to the first outer fitting member, and the first outer fitting member may have a first restricting member that restricts relative movement of the connecting bolt with respect to the first outer fitting member, and the pressure ring may have a second restricting member that restricts relative movement of the connecting bolt with respect to the main body portion.

[0068] [5] In any one of the leakage prevention devices [1] to [4] above, the pressure ring may include a pressing portion that presses the sealing material, a main body portion that is positioned away from the first outer fitting member in the pipe axis direction, a connecting bolt that connects the main body portion to the first outer fitting member, and an abutment bolt that abuts against the first outer fitting member, wherein the first outer fitting member has a pressure-receiving surface that receives the tip of the abutment bolt, and the pressure ring may include a female thread portion into which the abutment bolt is screwed, or a regulating member that regulates the relative movement of the abutment bolt with respect to the main body portion.

[0069] [6] In any one of the leakage prevention devices [1] to [5] above, the pressure ring may include a pressing portion that presses the sealing material, a main body portion that is arranged away from the first outer fitting member in the pipe axis direction, and a connecting bolt that connects the main body portion to the first outer fitting member, and a spacer may be arranged between the first outer fitting member and the main body portion to fill the gap therebetween.

[0070] [7] Furthermore, the leakage prevention structure for a pipe joint according to the present disclosure comprises a pipe joint connecting an end of the first fluid pipe and an end of the second fluid pipe, and any one of the leakage prevention devices [1] to [6] above is attached to the pipe joint. With this leakage prevention structure, even if an external force in the pipe axial direction that moves the first outer fitting member away from the pipe joint occurs due to an unexpected event, the gap between the first outer fitting member and the pressure ring is maintained and the compressed state of the sealing material does not change substantially, thereby suppressing a decrease in sealing performance.

[0071] [8] a first outer fitting member for fitting a first fluid pipe to a first fluid pipe, a second outer fitting member for fitting a second fluid pipe to a second fluid pipe, an expandable pipe extending in a pipe axial direction between the first outer fitting member and the second outer fitting member and surrounding a pipe joint portion where an end of the first fluid pipe and an end of the second fluid pipe are connected, and a second outer fitting member for connecting a pressure ring to the first outer fitting member via a connecting structure and pressing a sealant attached to a gap between an inner circumferential surface of the first outer fitting member and an outer circumferential surface of the first fluid pipe with the pressure ring. The connecting structure is configured so that the distance between the first outer fitting member and the pressure ring is maintained even when an external force acts in the pipe axial direction to move the first outer fitting member away from the pipe joint portion.

[0072] According to this method, even if an external force in the pipe axial direction occurs due to an unforeseen event that moves the first outer fitting member away from the pipe joint portion, the distance between the first outer fitting member and the pressure ring is maintained and the compression state of the sealing material does not change substantially, thereby preventing a decrease in sealing performance.

[0073] Although the embodiments of the present disclosure have been described, the specific configurations are not limited to these embodiments. The present disclosure is not limited to the above-described embodiments, and various improvements and modifications are possible within the scope of the gist thereof. The configurations described in the first to fourth embodiments above may be adopted in any combination. [Explanation of symbols]

[0074] 5 Connection structure 6 spacers 10 Leak prevention device 11 outer fitting member (first outer fitting member) 11a Holding part 11b Sealing material 11c Extension 11e Female thread 12 outer fitting member (second outer fitting member) 14 Flexible pipe (an example of an expansion pipe) 40 Splice 50 Push Ring 51 Pressing section 52 Connecting bolt 53 Main body 53s female thread 54 Abutment bolt 55 Pressure-receiving surface 56 Nut (an example of a restricting member) 57 Nut 58 Nut (an example of a restricting member) AD1 One side in the tube axis direction AD2 Other side of tube axis direction JT pipe joint P1 pipe (first fluid pipe) P2 pipe (second fluid pipe)

Claims

1. a first fitting member fitted onto the first fluid pipe; a second fitting member fitted onto the second fluid pipe; an expansion pipe extending in a pipe axis direction between the first outer fitting member and the second outer fitting member and surrounding a pipe joint portion at which an end of the first fluid pipe and an end of the second fluid pipe are connected; a sealant that seals a gap between an inner circumferential surface of the first outer fitting member and an outer circumferential surface of the first fluid pipe; a pressure ring connected to the first outer fitting member via a connecting structure and pressing the sealing material, The connection structure is a leakage prevention device configured so that the distance between the first outer fitting member and the pressure ring is maintained even when an external force acts in the pipe axial direction to move the first outer fitting member away from the pipe joint portion.

2. the pressure ring includes a pressing portion that presses the sealing material, a main body portion that is disposed apart from the first outer fitting member in the pipe axis direction, and a connecting bolt that connects the main body portion to the first outer fitting member, The leakage prevention device according to claim 1 , wherein the connecting structure is configured to transmit a force acting on the first outer fitting member due to the external force to the main body portion via the connecting bolt.

3. the pressure ring includes a pressing portion that presses the sealing material, a main body portion that is disposed apart from the first outer fitting member in the pipe axis direction, and a connecting bolt that connects the main body portion to the first outer fitting member, the first outer fitting member has a female thread portion into which the connecting bolt is screwed, The leakage prevention device according to claim 1 , wherein the pressure ring has a restricting member that restricts relative movement of the connecting bolt with respect to the main body portion.

4. the pressure ring includes a pressing portion that presses the sealing material, a main body portion that is disposed apart from the first outer fitting member in the pipe axis direction, and a connecting bolt that connects the main body portion to the first outer fitting member, the first outer fitting member has a first restricting member that restricts relative movement of the connecting bolt with respect to the first outer fitting member, The leakage prevention device according to claim 1 , wherein the pressure ring has a second restricting member that restricts relative movement of the connecting bolt with respect to the main body portion.

5. the pressure ring includes a pressing portion that presses the sealing material, a main body portion that is disposed apart from the first outer fitting member in the pipe axis direction, a connecting bolt that connects the main body portion to the first outer fitting member, and an abutting bolt that abuts against the first outer fitting member, the first outer fitting member has a pressure-receiving surface that receives the tip of the abutment bolt, The leakage prevention device according to claim 1 , wherein the pressure ring has a female threaded portion into which the abutment bolt is screwed, or a restricting member that restricts relative movement of the abutment bolt with respect to the main body portion.

6. the pressure ring includes a pressing portion that presses the sealing material, a main body portion that is disposed apart from the first outer fitting member in the pipe axis direction, and a connecting bolt that connects the main body portion to the first outer fitting member, The leakage prevention device according to claim 1 , wherein a spacer is disposed between the first outer fitting member and the main body portion so as to fill a gap therebetween.

7. A leakage prevention structure for a pipe joint portion, in which the leakage prevention device described in any one of claims 1 to 6 is attached to a pipe joint portion to which an end of the first fluid pipe and an end of the second fluid pipe are connected.

8. fitting a first fitting member onto the first fluid pipe; fitting a second fitting member onto the second fluid pipe; a step of joining one end of an expandable pipe, which extends in the pipe axis direction between the first outer fitting member and the second outer fitting member and surrounds a pipe joint portion where an end of the first fluid pipe and an end of the second fluid pipe are connected, to the first outer fitting member, and joining the other end of the expandable pipe to the second outer fitting member; connecting a press ring to the first outer fitting member via a connecting structure, and pressing a seal material attached to a gap between an inner circumferential surface of the first outer fitting member and an outer circumferential surface of the first fluid pipe with the press ring, A leakage prevention method in which the connecting structure is configured so that the distance between the first outer fitting member and the pressure ring is maintained even when an external force acts in the pipe axial direction to move the first outer fitting member away from the pipe joint portion.

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