Method of preventing leakage in pipe joint

Abstract

To provide a leakage prevention method of a pipe joint capable of improving workability when joining an end part of an expansion cover to an outer fitting member.SOLUTION: The method includes a step of arranging, along a pipe circumferential direction, an outer fitting member 11 to be externally fitted and attached to the pipe body 1, a step of arranging, along the pipe circumferential direction, a flexible pipe 14 as an expansion / contraction cover surrounding the pipe joint, and a joining step of joining an end portion of the flexible pipe 14 in a pipe axis direction to the outer fitting member 11 while rotating the outer fitting member 11 and the flexible pipe 14 in the pipe circumferential direction to adjust positions thereof.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to a leak prevention method for preventing fluid leakage in a pipe joint. [Background technology]

[0002] Patent Document 1 describes a leak prevention structure and method for a pipe joint developed by the present applicant. The leak prevention structure is constructed by attaching a leak prevention device to the pipe joint. The leak prevention device includes a pair of outer fitting members that are fitted onto the outside of the pipe body, and an expandable cover (flexible pipe) that extends between them in the pipe axial direction and surrounds the pipe joint. If the pipe body becomes detached from the pipe joint due to an earthquake or other action, the expandable cover deforms in response to the expansion, contraction, or tilt of the pipe, preventing fluid from leaking outside the device.

[0003] The work of installing the above-mentioned leak prevention device on an existing pipe joint includes the steps of placing the outer fitting member and the telescopic cover over the pipe and circumferentially arranging them, and joining the end of the telescopic cover in the pipe axis direction to the outer fitting member. However, at actual construction sites, it is often difficult to secure sufficient working space around the pipe joint, and the work of joining the end of the telescopic cover to the outer fitting member is very complicated, so there is still room for further improvement in this joining work. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-122565 Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure has been made in consideration of the above-mentioned situation, and its purpose is to provide a method for preventing leakage from a pipe fitting that can improve workability when joining the end of an extendable cover to an outer fitting member. [Means for solving the problem]

[0006] The disclosed method for preventing leakage in a pipe joint is a method for preventing fluid leakage due to separation of the pipe bodies by attaching a leakage prevention device to a pipe joint in which the ends of pipe bodies are connected to each other, and includes the steps of: arranging an outer fitting member to be fitted onto the outside of the pipe body along the pipe circumferential direction; arranging an expandable cover that surrounds the pipe joint along the pipe circumferential direction; and joining the end of the expandable cover in the pipe axial direction to the outer fitting member while rotating the outer fitting member and the expandable cover around the pipe to adjust their positions. [Brief explanation of the drawings]

[0007] [Figure 1] Schematic diagram of the water pipe bridge [Figure 2] Diagram showing a leak prevention device attached to a pipe fitting (upper half is a cross-sectional view) [Figure 3] Enlarged cross-sectional view showing the area around the pipe fitting [Figure 4] FIG. 10 is a diagram showing a state in which the pipe body is detached from the pipe joint. [Figure 5] FIG. 10 is a diagram showing a state in which the pipe body is detached from the pipe joint. [Figure 6] FIG. 4 is a cross-sectional view showing the periphery of the outer fitting member of FIG. [Figure 7] FIG. 10 is a diagram showing a modified example of the separation prevention mechanism. [Figure 8] FIG. 10 is a diagram showing a process of arranging the outer fitting member along the circumferential direction of the pipe. [Figure 9] FIG. 10 is a diagram showing a process of arranging the elastic cover in the circumferential direction of the pipe. [Figure 10] A diagram showing the process of attaching the press ring [Figure 11] Schematic diagram showing a manner in which the outer fitting member and the flexible pipe are rotated. [Figure 12] 1 is a cross-sectional view showing the periphery of an outer fitting member to which a first centering jig is attached; [Figure 13] FIG. 10 is a perspective view showing an example of a first centering jig; [Figure 14] A cross-sectional view showing the periphery of the outer fitting member to which the second centering jig is attached. [Figure 15] Cross-sectional view showing the periphery of the outer fitting member to which the third centering jig is attached [Figure 16] FIG. 10 is a perspective view showing an example of a third centering jig; [Figure 17] FIG. 10 is a cross-sectional view showing a modified example of the second centering jig. [Figure 18] Three-view diagram showing a modified example of the second centering jig DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of the method for preventing leakage from a pipe joint of the present disclosure will be described.

[0009] [Leak prevention structure of pipe joints] Before explaining the method for preventing leakage from a pipe fitting, the leakage prevention structure of the pipe fitting will be explained with reference to Figures 1 to 6. Figure 1 is a schematic diagram of a water pipe bridge. A pipe fitting JT, which connects the ends of pipes 1 that form the pipeline of a water pipe bridge 90, is equipped with a leakage prevention device 10 that prevents fluid leakage (water leakage) due to separation of the pipes 1. In Figure 1, the leakage prevention device 10 is simply depicted by a dashed line. The pipe 1 is, for example, a steel water pipe with a nominal diameter of 900, but specifications such as pipe dimensions can be changed as appropriate depending on the conditions of use.

[0010] The aquatic pipe bridge 90 is a bridge for fluid pipes (water pipes) that is installed to cross rivers, roads, railways, etc. The aquatic pipe bridge 90 is spanned between a pair of abutments 91. Piers 92 are installed midway along the pipes of the aquatic pipe bridge 90, but a pierless structure is also possible. The aquatic pipe bridge 90 has fixed support ends 90E that are fixedly supported by the abutments 91. In this embodiment, both ends of the aquatic pipe bridge 90 are embedded in the concrete that forms the abutment 91, and each end serves as a fixed support end 90E. Bearings 70 that support the vertical load of the aquatic pipe bridge 90 are installed on the abutments 91 and piers 92. The bearings 70 are fixed to the abutments 91 and piers 92 via anchor bolts.

[0011] 2 and 3, the leakage prevention device 10 includes a flexible pipe 14 as a metal expansion / contraction cover surrounding the pipe joint JT, and outer fitting members 11 and 12 joined to both axial ends of the flexible pipe 14 and fitted onto the pipe body 1. This device 10 forms an enclosed space around the pipe joint JT, preventing water leakage to the outside of the device even if the pipe body 1 becomes detached due to expansion / contraction of the pipeline caused by temperature changes or vibration or displacement caused by an earthquake, or if the sealing material 42, described below, deteriorates. In this embodiment, the leakage prevention device 10 is disposed in an area X sandwiched between a pair of supports 70 on the same abutment 91. Therefore, the outer fitting members 11 and 12 are both fitted onto the outer circumferential surface of the pipe body 1 within the area X.

[0012] The bearing 70 supports the pipe body 1 via a ring support 71. The ring support 71 surrounds the pipe body 1 in the pipe circumferential direction and is fixed to the outer surface of the pipe body 1 by welding or the like. The region X may be an region inside the ring support 71 (the side closer to the pipe joint JT). In this embodiment, an example is shown in which a pair of bearings 70 are installed on the same abutment 91, one of which is a movable bearing 70M and the other is a fixed bearing 70F. The movable bearing 70M is configured to allow displacement of the ring support 71 in the pipe axis direction and to absorb expansion and contraction of the pipe. The fixed bearing 70F is configured to allow rotational displacement of the ring support 71 around a horizontal axis 72 perpendicular to the pipe axis direction and to absorb eccentricity and tilt of the pipe.

[0013] The pair of supports 70 are fitted with bridge fall prevention devices 73 that restrict movement of the pipe body 1 in the direction that extends the pipe joint JT. The bridge fall prevention device 73 comprises a connecting cable 74 that is inserted into a through hole provided in the ring support 71, and a stopper 75 that is provided at the end of the connecting cable 74 and prevents it from slipping out of the through hole. The connecting cable 74 is made of PC steel strands or the like extending in the axial direction of the pipe. The stopper 75 has a built-in coil spring (not shown) that generates a biasing force in a direction that suppresses slack in the connecting cable 74. The installation of the bridge fall prevention device 73 is optional and may be omitted.

[0014] The pipe joint JT is configured as an expansion joint that can expand and contract along the pipe axis direction, and absorbs displacement such as expansion and contraction of the water pipe bridge 90 in cooperation with a bearing 70. In the pipe joint JT, the ends of the pipes 1 are connected to each other via a flange 40. A main pipe section 41 of the flange 40 is disposed across the ends of the pair of pipes 1, and the gap between the main pipe section 41 and the ends of the pipes 1 is sealed with a sealant 42. In this embodiment, the ends of the pipes 1 are formed by short pipe sections 43 joined by welding. Therefore, the pipe joint JT is an expansion joint that includes the short pipe section 43 joined to the pipes 1 by welding, and the main pipe section 41 that is inserted outside the short pipe section 43 so as to be displaceable relative to the short pipe section 43 in the pipe axis direction.

[0015] 4 and 5 show the pipe body 1 detached from the pipe joint JT. In FIG. 4, the allowable expansion / contraction of the movable support 70M has been exceeded, causing the ring support 71 to fall from the movable support 70M. In some cases, the ring support 71 may break midway and fall. A step prevention structure may be applied to prevent a step from occurring on the road surface (the upper surface of the abutment 91) due to the ring support 71 falling. The step prevention structure may be formed, for example, with a block-shaped member equipped with a shock-absorbing rubber and can be retrofitted to the support 70. In FIG. 5, the pipe is bent via the pipe joint JT. In FIGS. 4 and 5, the bridge fall prevention device 73 (not shown in FIGS. 4 and 5) restricts the expansion of the pipe, but the sealant 42 has fallen off the pipe body 1. The flexible pipe 14 has the function of preventing water leakage to the outside of the device and maintaining water flow in such a situation.

[0016] As described above, if the pipeline elongates significantly beyond the expansion and contraction allowance of the pipe joint JT and the pipe body 1 comes off at the pipe joint JT, the accompanying deformation of the flexible pipe 14 maintains the sealed space inside the device, allowing water to flow. However, if the extension or displacement is large enough to overcome the restrictions imposed by the bearing 70 and the bridge fall prevention device 73, there is a risk that the pipe body 1 will fall off the bearing 70 and the flexible pipe 14 will come into contact with the abutment 91. According to the leakage prevention structure of this embodiment, the flexible pipe 14 is made of metal, and the leakage prevention device 10 is located in area X, so that the ring support 71 can act as a support in the event of detachment, thereby preventing malfunction due to damage to the flexible pipe 14.

[0017] As shown in FIG. 3, the leakage prevention device 10 further includes a seal 11b that seals the gap between the pipe body 1 and the outer fitting member 11, and a press ring 50 that presses the seal 11b. The seal 11b is made of an elastic material such as rubber, as are the seals 12b and 42. The press ring 50 is connected to the outer fitting member 11 and is located within region X (see FIG. 2). A clearance is provided between the press ring 50 and the ring support 71 in the pipe axial direction. Similarly, a press ring 50 that presses the seal 12b is connected to the outer fitting member 12. Therefore, the seals 11b and 12b and the press ring 50 (including the pressing portion 51, connecting bolt 52, main body 53, etc.) that press them are all located within region X.

[0018] As shown in FIG. 6, 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 diameter direction. The retaining portion 11a is formed as a tubular body having an inner diameter dimension that allows it to be fitted onto the pipe body 1. 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 diameter 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.

[0019] In this embodiment, the retaining portion 11a is integrally formed with the extension body 11c and also serves as a flange to which the connecting bolt 52 is attached, so the gap between the extension body 11c and the flange is essentially zero. This allows the leakage prevention device 10 to be configured compactly, which is convenient for arranging the device 10 in a narrow space within the region X. The thickness of the extension body 11c may be increased partially or entirely so that the extension body 11c also serves as a flange. The outer fitting member 12 has a retaining portion 12a that retains the sealing material 12b and an extension body 12c that extends in the pipe radial direction (see FIG. 3). 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.

[0020] As shown in FIG. 2, the leakage prevention device 10 of this embodiment includes a tie rod 13 inserted through a rod hole formed in each of 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. Note that the installation of the tie rod 13 is optional and may be omitted.

[0021] 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 pipe line. Therefore, if the pipe body 1 is separated from 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.

[0022] 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.

[0023] 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 of a metal extension member 14E, which is a separate member from the main body formed as a corrugated pipe (see FIG. 6). The joining of the extension member 14E to the main body is performed by welding, but mechanical joining using bolts, rivets, etc. is also possible. The type of joint used when joining is not limited to a lap joint, and may be a butt joint, etc.

[0024] As shown in Figure 6, 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. Therefore, 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.

[0025] In this embodiment, a separation prevention mechanism 60 is applied to prevent the tubular body 1 from separating from the outer fitting members 11, 12. The separation prevention mechanism 60 has a pressing bolt 59 as a locking portion that can be locked onto the outer circumferential surface of the tubular body 1 in the region X, and is provided integrally with the pressing ring 50. The pressing bolt 59 is threaded into a threaded hole provided in a portion that protrudes from the main body 53 toward one axial side AD1. A claw portion is formed at the tip of the pressing bolt 59 on the inner side in the diametrical direction of the tubular body, so that the claw portion can be locked onto the outer circumferential surface of the tubular body 1. The pressing bolts 59 are arranged at multiple locations around the circumferential direction of the tubular body. The separation prevention effect is achieved by having the pressing bolt 59 protrude inward in the diametrical direction of the tubular body and by firmly locking the claw portion at the tip of the pressing bolt 59 onto the outer circumferential surface of the tubular body 1.

[0026] The structure of the detachment prevention mechanism 60 is not particularly limited, and may be, for example, a structure as shown in FIG. 7. In the example shown in FIG. 7, the pressure bolt 59 is formed as a separate member from the pressure ring 50. The detachment prevention mechanism 60 has a connecting portion 62 that connects the pressure bolt 59 to the water leakage prevention device 10. The connecting portion 62 is composed of a bolt and nut. The bolt is threaded into a threaded hole provided in the extension body 11c. The pressure bolt 59, which serves as a locking portion, is connected to the outer fitting member 11 (the extension body 11c) via the connecting portion 62. The detachment prevention mechanism 60 is attached to the water leakage prevention device 10 without the pressure ring 50 interposed therebetween. This makes it possible to attach the detachment prevention mechanism 60 after the pressure ring 50 has been installed.

[0027] 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 tubular body 1. While Fig. 6 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 tubular body 1, the nut 58 is tightened and the pressing bolt 59 is engaged with the outer peripheral surface of the tubular body 1 after the pressure ring 50 is brought close to the outer fitting member 11 to seal the gap with the sealing material 11b. One side AD1 in the axial direction of the tube corresponds to the side opposite the direction in which the pressure ring 50 presses the sealing material 11b, and the other side AD2 in the axial direction of the tube corresponds to the side in the direction in which the sealing material 11b is pressed.

[0028] If the device becomes filled with water due to the removal of the pipe body 1 and water pressure is generated, an external force acts in the pipe axial direction, moving the outer fitting member 11 toward one side AD1 in the pipe axial direction (the side away from the pipe joint JT). If this external force causes the outer fitting member 11 to move relative to the pipe body 1, the gap between the pressure ring 50 and the outer fitting member 11 may decrease, causing overcompression of the sealing material 11b and uneven surface pressure. Therefore, in this embodiment, the relative movement of the connecting bolt 52 with respect to the main body 53 is restricted by a nut 58, thereby maintaining the gap between the outer fitting member 11 and the pressure ring 50. This prevents substantial changes in the compression state of the sealing material 11b and suppresses deterioration of sealing performance. Water filling the device can be discharged through a valve 9 (see FIG. 3).

[0029] The joint 43J of the short pipe section 43 is located within the region X, and the weld bead has been removed. This is convenient because the device 10 is not restricted by the weld bead when being placed in the narrow space within the region X. The traces of the removed weld bead extend along the circumferential direction of the pipe, and the outer circumferential surface of the joint 43J is formed by a smoothly curved surface. When the seal materials 11b, 12 are placed outside the joint 43J (the side away from the pipe joint JT), the weld bead does not necessarily have to be removed, but in many cases there is not enough space to allow this. Therefore, it is preferable to remove the weld bead as in this embodiment, from the viewpoint of avoiding interference with the seal materials 11b, 12b and the pressure ring 50.

[0030] [Methods for preventing leaks from pipe fittings] A method for preventing leakage from a pipe joint will be described with reference to Figures 8 to 18. This method is a method for attaching a leakage prevention device 10 to a pipe joint JT to prevent fluid leakage due to separation of a pipe body 1, and includes a step of arranging an outer fitting member 11 to be fitted onto the pipe body 1 in the pipe circumferential direction (first arrangement step), a step of arranging a flexible pipe 14 as an expandable cover surrounding the pipe joint JT in the pipe circumferential direction (second arrangement step), and a step of joining the end of the flexible pipe 14 in the pipe axial direction to the outer fitting member 11 (joining step). These steps will first be outlined with reference to Figures 8 to 10, and then the main points will be explained. The construction method for the outer fitting member 11 explained below can be similarly applied to the outer fitting member 12, so repeated explanations will be omitted.

[0031] FIG. 8 shows the first placement step, and does not include the bearings 70 and ring support 71. In this embodiment, as shown in FIGS. 8(A) to 8(C), the semicircular arc-shaped segment 11X is lifted by a crane, placed over the pipe body 1, and placed in a predetermined position. The semicircular arc-shaped segment 11Y is then set to form a ring shape, and the end faces of the segments 11X and 11Y are butted together at a joint 11Z, which is welded together. In FIG. 8(C), fasteners (bolts and nuts) are attached across the joint 11Z to temporarily fasten the segments 11X and 11Y, but these may be removed after the joint 11Z is joined. The outer fitting member 12 can be attached in the same manner as the outer fitting member 11.

[0032] It is preferable to have a step of removing the weld bead from the joint 43J of the short pipe section 43 (not shown in Figures 8 to 10, etc.) prior to the first arrangement step. The reason for removing the weld bead is as described above. This step may be performed after the first arrangement step, but considering the ease of removing the weld bead, it is preferable to perform it before the first arrangement step. In addition to removing the weld bead, the paint on the outer surface of the pipe body 1 at the attachment points of the outer fitting members 11, 12 is also removed. These steps can be performed using a grinding tool such as a grinder.

[0033] FIG. 9 illustrates the second placement step, and the support 70 and ring support 71 are omitted. The second placement step may be performed before the first placement step. In this embodiment, as shown in FIGS. 9(A) to 9(C), the semicircular arc-shaped segment 14X is lifted by a crane, placed over the pipe body 1, and then placed in a predetermined position. The semicircular arc-shaped segment 14Y is then set in place to form a circular ring. At this stage, the joints 14Z where the end faces of the segments 14X and 14Y butt against each other are not yet joined. The flexible pipe 14, which is a state where the multiple segments 14X and 14Y are not yet joined to each other, is placed between the outer fitting member 11 and the outer fitting member 12. Therefore, it is preferable to temporarily fix these segments 14X and 14Y by tack welding or the like.

[0034] 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 1, the gap between the inner circumferential surface of the outer fitting member 12 and the outer circumferential surface of the pipe 1, 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 such as argon gas, which is necessary for welding the joint 14Z. In this embodiment, the shielding gas is injected through a communication hole 7 (see FIG. 6) 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. 6) is attached to close the communication hole 7. The communication hole 7 can also be provided in the outer fitting members 11 and 12.

[0035] 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.

[0036] 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.

[0037] Next, as shown in FIG. 10(A), the divided pressure ring 50 is fitted onto the tubular body 1, and the sealing material 11b is arranged in an annular shape along the outer circumferential surface of the tubular body 1. The sealing material 11b is arranged in an annular shape by wrapping a strip-shaped member around the circumferential direction of the pipe and gluing its ends together. The portion of the pressure ring 50 including the pressing portion 51 and the main body portion 53 consists of multiple divided pieces each having a semicircular arc shape. These are combined to form an annular ring, and then the end faces of the divided pieces are butted together and welded together. The jig 80 will be described later. 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] 10(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. During this time, the nut 58 is moved toward the other axial side AD2 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 peripheral surface of the pipe body 1. The sealing material 11b is pressed along the axial direction by the pressing part 51, which moves together with the main body 53, to seal the gap between the inner peripheral surface of the outer fitting member 11 and the outer peripheral surface of the pipe body 1. 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] 10(C), the nut 58 is brought into contact with the main body 53, restricting the relative movement of the connecting bolt 52 with respect to the main body 53. This maintains the distance between the outer fitting member 11 and the press ring 50 even when an external force acts in the pipe axial direction to move the outer fitting member 11 away from the pipe joint JT. Nuts 58 do not need to be attached to all connecting bolts 52 around the pipe circumference; they may be attached at appropriate intervals, for example, at four locations around the pipe circumference. After connecting the press ring 50 to the outer fitting member 11, the press bolt 59 is operated to lock its tip against the outer peripheral surface of the pipe body 1.

[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 that connects 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 fitting JT, and as a result, deterioration in the sealing performance of the outer fitting member 12 is also suppressed. Then, by attaching tie rods 13 to the outer fitting members 11, 12 and further attaching a bridge fall prevention device 73, the leakage prevention structure for the pipe fitting shown in Figure 2 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 gas (e.g., a shielding gas such as argon gas, or nitrogen gas) injected into the flexible pipe 14. After the test, the necessary areas are painted, and the construction is completed.

[0042] However, at actual construction sites, it is often difficult to secure sufficient working space around the pipe joint JT. For example, in situations where the gap between the abutment 91 and the pipe joint JT is too narrow for a worker to enter below the pipeline, the work of welding the end of the flexible pipe 14 to the outer fitting member 11 along the circumferential direction of the pipe becomes extremely complicated. Therefore, in this embodiment, in the joining process, the outer fitting member 11 and the flexible pipe 14 are rotated in the circumferential direction of the pipe to adjust their positions, while the end of the flexible pipe 14 is joined to the outer fitting member 11. This allows welding to be performed at a convenient position, such as above or to the side of the pipeline, improving workability during joining.

[0043] The outer fitting member 11 and the flexible pipe 14 can be rotated, for example, in the manner shown in Figure 11. Either method can be used to rotate the outer fitting member 11 and the flexible pipe 14 around the pipe axis and relative to the pipe body 1. Figure 11(A) shows an example in which a lifting tool such as a crane is used. Figures 11(B) to 11(D) show examples in which a towing tool such as a lever block or a chain block is used. As shown in Figure 11(D), a rotational force can be generated by towing a platform 16 on which the outer fitting member 11 and the flexible pipe 14 are placed. Any combination of these methods can also be used.

[0044] It is preferable to temporarily join the outer fitting member 11 and the flexible pipe 14 before the joining step, and then rotate the temporarily joined outer fitting member 11 and flexible pipe 14 in the circumferential direction of the pipe during the joining step. This maintains the relative positional relationship between the outer fitting member 11 and the flexible pipe 14, improving the workability of the joining step. For the temporary joining, for example, tack welding or spot welding is used. It is preferable that such temporary joining be performed after the second centering step described below. It is also preferable that the outer fitting member 11 and the outer fitting member 12 are connected using a connecting member 17 (see FIG. 14) described below, and the temporary joining is performed with the flexible pipe 14 sandwiched between them.

[0045] If the gap between the tubular body 1 and the outer fitting member 11 is uneven after the first positioning step (see FIG. 8(C)), it becomes difficult to accurately join the end of the flexible tube 14 to the outer fitting member 11. Therefore, it is preferable to have a first centering step of centering the outer fitting member 11 relative to the tubular body 1 before the joining step. In this embodiment, in the first centering step, as shown in FIG. 12, a centering jig 20 (corresponding to the first centering jig) attached to the outer side of the outer fitting member 11 is used to adjust the gap between the tubular body 1 and the outer fitting member 11. Here, the side of the outer fitting member 11 to which the end of the flexible tube 14 is joined (the other axial side AD2) is referred to as the inner side of the outer fitting member 11, and the opposite side (the one axial side AD1) is referred to as the outer side of the outer fitting member 11.

[0046] As shown in Figures 12 and 13, the centering jig 20 includes a main body 21, a fixing bolt 22, a pressing bolt 23, and an attitude adjustment bolt 24. The main body 21 is placed against the outer fitting member 11, and in this state, the fixing bolt 22 is threaded into the female thread portion 11e. The tip of the pressing bolt 23 abuts against the outer peripheral surface of the tubular body 1, and by manipulating this, the gap between the tubular body 1 and the outer fitting member 11 can be adjusted. The tip of the attitude adjustment bolt 24 abuts against the outer peripheral surface of the outer fitting member 11 (the holding portion 11a thereof), and by manipulating this, the attitude (inclination) of the pressing bolt 23 can be finely adjusted. The centering jig 20 is attached to multiple locations (for example, four locations) around the periphery of the pipe and is used to equalize the gap between the tubular body 1 and the outer fitting member 11 (i.e., centering).

[0047] 12 and 14 show the position where the tie rod attachment portion 11f having a rod hole is extended radially outward from the extension body 11c, and a similar tie rod attachment portion is also provided on the outer fitting member 12. In this embodiment, after centering is performed by attaching a centering jig 20 to the outer side of the outer fitting member 12 as well as to the outer fitting member 11, the outer fitting member 11 and the outer fitting member 12 are connected using a shaft-shaped connecting member 17 (the tie rod 13 can also be used) as shown in FIG. 14. This allows the outer fitting members 11 and 12 to be temporarily fixed in an orientation where the rod holes for inserting the tie rod 13 are coaxially arranged and the extension bodies 11c and 12c extending radially of the pipe are parallel to each other. It is preferable to attach the centering jig 80, which will be described later, after this temporary fixation.

[0048] In this embodiment, after the first centering step, a centering jig 80 (corresponding to the second centering jig) arranged on the inner side of the outer fitting member 11 is used to maintain the gap even when the centering jig 20 is removed. This is because the centering jig 20 must be removed in the step of attaching the sealing material 11b and the press ring 50 (see FIG. 10). The centering jig 80 shown in FIG. 14 is fixed by welding to the outer fitting member 11 (extension 11c thereof) with its inner end in the pipe diameter direction abutting against the outer peripheral surface of the pipe body 1. The centering jig 80 is formed from a plate- or rod-shaped metal piece and is attached at multiple locations (for example, five locations) around the pipe circumference.

[0049] When moving from the state shown in FIG. 14 to the second arrangement step, the connecting member 17 is removed and then the flexible pipe 14 is set as described with reference to FIG. 9. The centering jig 80 is sized to fit within the internal space of the flexible pipe 14, and can therefore be left in place. Therefore, in the joining step, the outer fitting member 11 and the flexible pipe 14 are rotated with the centering jig 80 fixed in place. The centering jig 20 is removed at the required timing after the gap between the pipe body 1 and the outer fitting member 11 is maintained by the second centering jig (centering jig 80 in the example of FIG. 14).

[0050] After the second arrangement step (see FIG. 9(C)), when the flexible pipe 14 (including the state in which the multiple divided pieces 14X, 14Y are temporarily fixed) is placed on the pipe body 1, it becomes difficult to accurately join the end of the flexible pipe 14 to the outer fitting member 11. Therefore, it is preferable to have a second centering step in which the flexible pipe 14 is centered with respect to the outer fitting member 11 before the joining step. In this embodiment, in the second centering step, the flexible pipe 14 is supported from below using a centering jig 85 (corresponding to a third centering jig) attached to the outer fitting member 11 as shown in FIG. 15. The centering jig 85 is removed after the outer fitting member 11 and the flexible pipe 14 are temporarily joined or after the joining step.

[0051] As shown in Figures 15 and 16, the centering jig 85 includes a plate-shaped main body 86, a support member 87, and a press bolt 88. One side of the main body 86 is provided with a flat portion 86a where the support member 87 is not disposed. The centering jig 85 is fixed by clamping the (extension 11c of) the outer fitting member 11 and the flat portion 86a of the main body 86 placed thereon with a clamp or other clamping tool (not shown). The support member 87 is formed by a nut and is fixed to the main body 86 by welding. The press bolt 88 is supported by the support member 87, and its tip abuts against the outer peripheral surface of the flexible pipe 14 (the divided piece 14X disposed below). The centering jig 85 is attached at multiple locations around the pipe circumference, and can be attached not only below but also above.

[0052] As described above, when injecting a shielding gas into the internal space of the flexible pipe 14, it is necessary to seal each gap. To seal the gap between the end of the flexible pipe 14 and the outer fitting member 11, seal welding may be used to provide airtightness. In order to improve workability, it is preferable to perform such seal welding while rotating the outer fitting member 11 and the flexible pipe 14 circumferentially to adjust their positions. Note that even when seal welding is performed, a joining process is performed to join the end of the flexible pipe 14 to the outer fitting member 11 after injecting the shielding gas and completing the joining of the joint 14Z.

[0053] In the present embodiment, an example has been shown in which the second centering jig is a centering jig 80 fixed to the inner side of the outer fitting member 11, but this is not limiting and modified examples such as those shown in Figures 17 and 18 are conceivable. These second centering jigs (centering jigs 30, 32) are both configured to be movable between a contact position in contact with the outer peripheral surface of the tubular body 1 and a separated position separated from the outer peripheral surface of the tubular body 1. In the joining process, by rotating the outer fitting member 11 and the flexible pipe 14 with the second centering jig displaced to the separated position, it is possible to rotate the outer fitting member 11 and the flexible pipe 14 without the second centering jig getting caught on the outer peripheral surface of the tubular body 1 even if the outer peripheral surface is distorted due to being bent flat, for example.

[0054] The centering jig 30 (corresponding to the second centering jig) shown in FIG. 17 includes a shaft member 31 that passes through the flexible pipe 14 and extends in the pipe diameter direction. The shaft member 31 is supported so as to be displaceable in the pipe diameter direction in response to operations performed outside the flexible pipe 14. The shaft member 31 is composed of a press bolt that is screwed into a threaded hole 14h provided in (the extension member 14E of) the flexible pipe 14. The shaft member 31 has a head portion 31h that serves as an operating portion and is disposed outside the flexible pipe 14, and a tip portion 31e that can abut against the outer peripheral surface of the tubular body 1 inside the flexible pipe 14. After the centering jig 30 is removed, the threaded hole 14h is closed by attaching a plug (not shown).

[0055] The centering jig 32 (corresponding to the second centering jig) shown in FIG. 18 includes a shaft member 33 that passes through the flexible pipe 14 and extends in the pipe diameter direction. The shaft member 33 is supported so as to be displaceable in the pipe diameter direction in response to an operation performed outside the flexible pipe 14. The shaft member 33 is composed of a press bolt that is inserted into a notch 14n provided in (the extension member 14E of) the flexible pipe 14. The shaft member 33 has a head portion 33h that serves as an operation portion that is disposed outside the flexible pipe 14, and a tip portion 33e that can abut against the outer peripheral surface of the pipe body 1 inside the flexible pipe 14. After the centering jig 32 is removed, the notch 14n is closed by welding a plate material.

[0056] The centering jig 32 has a main body 34 that supports the shaft member 33, and a fixing bolt 35 and an attitude adjustment bolt 36 are attached to the main body 34. An abutment portion 37 provided on the main body 34 is placed against the inner side of the outer fitting member 11, and the tip of the fixing bolt 35 is pressed against the outer side of the outer fitting member 11. The main body 34 is fixed by clamping the outer fitting member 11 (extension body 11c) between the abutment portion 37 and the fixing bolt 35. The tip of the attitude adjustment bolt 36 is placed in abutment against the outer peripheral surface of the flexible pipe 14 (extension member 14E), and by manipulating this, the attitude (tilt) of the shaft member 33 can be finely adjusted.

[0057] [Other variations] In the above-described embodiment, the pipe joint JT has an example of a sleeve joint structure in which the ends of the pipes 1 are connected to each other via a flange 40, but this is not limiting. For example, a joint structure in which one pipe is connected by fitting a spigot formed at the end of the other pipe into a socket formed at the end of the other pipe may also be used. In such a case, it is preferable to use an expansion joint that is configured to be expandable and contractible in the pipe axial direction between the socket and spigot.

[0058] In the above-described embodiment, an example was shown in which the telescopic cover was a flexible pipe 14, but this is not limited thereto, and any telescopic tubular body that surrounds a pipe joint can be used without any particular restrictions. Therefore, for example, it is also possible to use, as the telescopic cover, an telescopic pipe that includes 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 in which the first cylindrical body and the second cylindrical body are configured to be relatively movable along the pipe axis direction.

[0059] In the above-described embodiment, the outer fitting member 11 is watertightly fitted onto the tubular body 1 via the sealing material 11b, but this is not limiting. For example, it is also possible to weld the inner end of the outer fitting member 11 in the pipe diameter direction to the outer peripheral surface of the tubular body 1 without using the sealing material 11b, thereby achieving a watertight fitting. This configuration eliminates the need for the press ring 50 and makes the leakage prevention device more compact, which is convenient for rotating the outer fitting member 11 and the flexible pipe 14 during the joining process. The same applies to the outer fitting member 12.

[0060] In the above-described embodiment, an example was shown in which the pipe joint JT to which the leakage prevention device 10 is attached is located within the area sandwiched between a pair of bearings 70 in the same abutment 91, but this is not limited thereto, and the pipe joint JT may be located, for example, within the area sandwiched between a pair of bearings 70 in the same pier 92, or within the area sandwiched between a bearing 70 and the fixed support end 90E in the same abutment 91. Of course, the pipe joint to which the method of the present disclosure is applied does not have to be a pipe joint in an aqueduct bridge. However, in the abutments and piers of an aqueduct bridge, it is often difficult to secure sufficient working space around the pipe joint, and the work of joining the end of the telescopic cover to the external fitting member is complicated, making the method of the present disclosure particularly useful.

[0061] It will be understood by those skilled in the art that the above-described embodiments are examples of the following aspects.

[0062] [1] A leakage prevention method for a pipe joint according to the present disclosure is a method for preventing fluid leakage due to separation of the pipes by attaching a leakage prevention device to a pipe joint in which the ends of pipes are connected to each other, the method comprising the steps of: arranging an outer fitting member to be fitted onto the outside of the pipe along the pipe circumferential direction; arranging a telescopic cover surrounding the pipe joint along the pipe circumferential direction; and joining an end of the telescopic cover in the pipe axial direction to the outer fitting member while rotating the outer fitting member and the telescopic cover in the pipe circumferential direction to adjust their positions. This improves the ease of joining the end of the telescopic cover to the outer fitting member.

[0063] [2] In the leakage prevention method [1] above, the outer fitting member and the expandable cover may be temporarily joined before the joining process, and in the joining process, the outer fitting member and the expandable cover temporarily joined to each other may be rotated in the circumferential direction of the pipe.

[0064] [3] In the leakage prevention method of [1] or [2] above, the pipe joint may be an expansion joint having a short pipe section joined to the pipe body by welding and a main pipe section inserted outside the short pipe section so as to be displaceable relative to the short pipe section in the pipe axial direction, and the method may include a step of removing the weld bead at the joint of the short pipe section.

[0065] [4] In any one of the leakage prevention methods [1] to [3] above, a first centering step of centering the outer fitting member relative to the tubular body may be included before the joining step, and in the first centering step, a first centering jig attached to the outer side of the outer fitting member may be used to adjust the gap between the tubular body and the outer fitting member.

[0066] [5] In the leakage prevention method [4] above, after the first centering step, a second centering jig positioned on the inner side of the outer fitting member may be used so that the gap is maintained even when the first centering jig is removed.

[0067] [6] In the leakage prevention method [5] above, before the joining process, the second centering jig abutted against the outer surface of the pipe body may be fixed to the inner side of the outer fitting member, and in the joining process, the outer fitting member and the telescopic cover may be rotated with the second centering jig fixed.

[0068] [7] In the leakage prevention method [5] above, the second centering jig may be configured to be displaceable between a contact position in which it contacts the outer peripheral surface of the pipe body and a separated position in which it is separated from the outer peripheral surface of the pipe body, and in the joining process, the outer fitting member and the telescopic cover may be rotated with the second centering jig displaced to the separated position.

[0069] [8] In the leakage prevention method [7] above, the second centering jig may have an axial member that passes through the telescopic cover and extends in the pipe diameter direction, and the axial member may be supported so as to be freely displaceable in the pipe diameter direction in response to operation outside the telescopic cover.

[0070] [9] In any one of the leakage prevention methods [1] to [8] above, a second centering step may be included before the joining step to center the telescopic cover relative to the outer fitting member, and in the second centering step, the telescopic cover may be supported from below using a third centering jig attached to the outer fitting member.

[0071] 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 present disclosure. The configurations described in the above-described embodiments may be adopted in any combination. [Explanation of symbols]

[0072] 1. Body 10 Leak prevention device 11 Outer fitting member 12 Outer fitting member 14 Flexible pipe (an example of a telescopic cover) 20 Centering jig (first centering jig) 30 Centering jig (second centering jig) 31 Shaft member 32 Centering jig (second centering jig) 33 Shaft member 43 Short pipe section 43J Joint 80 Centering jig (second centering jig) 85 Centering jig (third centering jig)

Claims

1. A leakage prevention method for a pipe joint, in which a leakage prevention device is attached to a pipe joint in which ends of pipe bodies are connected to each other, and fluid leakage caused by separation of the pipe bodies is prevented, a step of arranging an outer fitting member to be fitted onto the outer surface of the pipe along the pipe circumferential direction; a step of placing an expandable cover surrounding the pipe joint along a circumferential direction of the pipe; A method for preventing leakage from a pipe fitting, characterized by including a joining process in which the end of the telescopic cover in the pipe axis direction is joined to the outer fitting member while rotating the outer fitting member and the telescopic cover in the pipe circumferential direction to adjust their positions.

2. The outer fitting member and the elastic cover are temporarily joined together before the joining step, The method for preventing leakage from a pipe joint according to claim 1, wherein the joining step rotates the outer fitting member and the expandable cover that are temporarily joined together in a circumferential direction of the pipe.

3. the pipe joint is an expansion pipe joint including a short pipe section joined to the pipe body by welding, and a main pipe section inserted externally so as to be displaceable relative to the short pipe section in the pipe axial direction, 2. The method for preventing leakage from a pipe joint according to claim 1, further comprising the step of removing a weld bead at the joint of said short pipe section.

4. a first centering step of centering the outer fitting member relative to the pipe body before the joining step; The method for preventing leakage from a pipe fitting according to claim 1, wherein the first centering step includes adjusting the gap between the pipe body and the outer fitting member using a first centering jig attached to the outer side of the outer fitting member.

5. A method for preventing leakage from a pipe fitting as described in claim 4, wherein after the first centering step, a second centering jig is used that is positioned on the inner side of the outer fitting member so that the gap is maintained even when the first centering jig is removed.

6. Before the joining step, the second centering jig is fixed to an inner side of the outer fitting member in contact with the outer peripheral surface of the pipe body; The method for preventing leakage from a pipe joint according to claim 5, wherein in the joining step, the outer fitting member and the extendable cover are rotated in a state in which the second centering jig is fixed.

7. the second centering jig is configured to be displaceable between a contact position in contact with the outer peripheral surface of the tube body and a spaced position spaced from the outer peripheral surface of the tube body, The method for preventing leakage from a pipe joint according to claim 5, wherein in the joining step, the outer fitting member and the extendable cover are rotated in a state in which the second centering jig is displaced to the separated position.

8. the second centering jig includes a shaft member that penetrates the telescopic cover and extends in a pipe radial direction, 8. The method for preventing leakage from a pipe joint according to claim 7, wherein the shaft member is supported so as to be displaceable in the pipe diameter direction in response to an operation performed outside the extendable cover.

9. a second centering step of centering the telescopic cover relative to the outer fitting member before the joining step; A method for preventing leakage from a pipe fitting as described in any one of claims 1 to 8, wherein in the second centering step, the telescopic cover is supported from below using a third centering jig attached to the outer fitting member.

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