JP5819179B2 - Repair expansion / contraction flexible joint - Google Patents

Description

  The present invention relates to a repairable expansion / contraction flexible joint, and in particular, when a joint between a joint and a pipe is damaged in a situation where the pipes are connected to each other by a joint and buried underground, the damaged joint is covered from the outside. The present invention relates to a repairable expansion / contraction flexible joint that repairs a connection relationship between pipes.

  Generally, pipes used for agricultural water, industrial water, waterworks, etc. are arranged in a groove dug in the ground made of PC pipe or steel pipe, and the ends of adjacent pipes are pipe joints It is buried in the ground by connecting with and filling the groove dug in the ground with soil.

  In a pipe line buried in the ground, when the pipe body is displaced by vibration due to an earthquake or the like and the pipe joint part connecting the pipes is damaged, leakage may occur in the pipe joint part. If the pipe body is large enough to allow the operator to enter the pipe joint when leakage occurs, the operator enters the pipe body and the pipe inner surface repair joint is attached to the leaked pipe joint. It is possible to stop the leakage of the pipe joint part by installing.

  In addition, when a leak occurs in the pipe joint part, the leaked pipe joint part itself is not directly repaired, but the end of the adjacent pipe part straddling the outside length range of the leaked pipe joint part. It is known to repair a leaked tube joint part by connecting the parts with a repairable expansion / contraction flexible joint.

Japanese Patent Laid-Open No. 2007-170475

  When installing a repairable expansion / contraction flexible joint outside the leaked tube joint and repairing the tube joint, the conventional repair expansion / contraction flexible joint requires a sufficient outside length range for the leaked tube joint. It was configured so that leakage would not occur outside the cover repair expansion / contraction flexible joint. That is, conventionally, the idea that the length of the repairable expansion / contraction flexible joint may be a length that can cover the length range of the leaked tube joint has been adopted.

  However, in situations where there is a possibility of an unexpected large earthquake or liquefaction phenomenon of the ground, an unexpected large shift occurs in the length direction between the ends of adjacent pipes, and repair expansion and contraction occurs. There is a risk of new leakage occurring to the flexible joint.

  On the other hand, in order to be able to cope with a larger expansion / contraction amount between the end portions of adjacent tubular bodies, it is conceivable to lengthen the length of the repair expansion / contraction flexible joint and increase the expansion / contraction amount. However, unless the diameter of the repairable expansion / contraction flexible joint is further increased, increasing the length of the repairable expansion / contraction flexible joint has a problem that the amount of eccentricity allowed in the axial direction between the opposite pipes becomes smaller. There is a limit to lengthening the length of the repairable expansion / contraction flexible joint. Further, the length of the repairable expansion / contraction flexible joint is specified by the site where it is used, and compactness is often required.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a repairable expansion / contraction flexible joint that can solve the above-described problems of the prior art and can cope with a large expansion / contraction amount for a limited length.

In order to achieve the above object, a repairable expansion / contraction flexible joint according to the present invention is a repairable expansion / contraction flexible joint that connects a first pipe and a second pipe connected by a joint in a freely stretchable manner.
A first sleeve into which an end of the first pipe and an end of the second pipe are inserted;
An outer sleeve provided on the outer side of the first sleeve so as to be movable relative to the first sleeve in an axial direction between a state of being overlapped with the first sleeve and a state of being released from the overlap;
A first sealing material that provides a fluid-tight seal between the inner peripheral surface of the first sleeve and the outer peripheral surface of the end portion of the first pipe so that the first sleeve and the first pipe are relatively movable in the axial direction. When,
A second sealing material that provides a fluid-tight seal between the inner peripheral surface of the outer sleeve and the outer peripheral surface of the second pipe so that the outer sleeve and the second pipe are relatively movable in the axial direction;
A third sealing material that provides a liquid-tight seal between the outer peripheral surface of the first sleeve and the inner peripheral surface of the outer sleeve so that the first sleeve and the outer sleeve are relatively movable in the axial direction;
The joint is broken and acts on the first sleeve so as to move the first sleeve toward the opposite end of the first pipe, and moves the outer sleeve toward the opposite end of the second pipe. When the external force acting on the outer sleeve does not exceed a predetermined threshold value, the outer sleeve is maintained in the overlapped state , and when the external force exceeds the predetermined threshold value, the overlapped state is released and applied to the first sleeve. And a brake part for restricting relative movement of the outer sleeve in the axial direction with respect to the first sleeve, which enables relative movement of the outer sleeve.

  The first sleeve may be divided into a first sleeve portion attached to an end portion of the first pipe and a second sleeve portion attached to an end portion of the second pipe. To do.

  The outer sleeve may be a single outer configuration sleeve disposed outside the first sleeve.

  The outer sleeve is composed of a plurality of constituent sleeves arranged to overlap each other, and includes an inner constituent sleeve located on the inner side of the plurality of constituent sleeves and an outer constituent sleeve provided outside the inner constituent sleeve. In the meantime, an outer brake part for restricting relative movement of the outer constituent sleeve in the axial direction with respect to the inner constituent sleeve is provided.

  Further, the brake portion has a fuse body laid between the outer sleeve and the first sleeve, and the fuse body has the outer sleeve and the first sleeve when the external force does not exceed the predetermined threshold. It is constructed such that it is constructed between one sleeve and maintained in a state where the external force is cut when the external force exceeds the predetermined threshold.

  In addition, the first seal material forms a first gap between an inner peripheral surface of the first sleeve and an outer peripheral surface of the joint, and the second seal material and the third seal material are the first sleeve. A second gap is formed between the outer circumferential surface of the outer sleeve and the inner circumferential surface of the outer sleeve, and the first gap and the second gap are within a predetermined range between the first pipe and the second pipe. It is set to allow bending movement.

  In the above-described invention, when the expansion / contraction flexible joint that connects the first pipe and the second pipe to be repaired is damaged, the first pipe and the second pipe are connected and repaired from the outside in a liquid-tight manner, Even when the first pipe and the second pipe are extended, the repair expansion / contraction flexible joint is extended following the judgment of the relationship with the magnitude of the external force applied by the brake portion, and the first pipe and the second pipe are liquid-tight. Hold on.

  According to the configuration of the present invention, the repairable expansion / contraction flexible joint includes the first sleeve and the outer sleeve disposed in a state of being overlapped with each other, and the brake portion that restricts the relative movement in the axial direction of the outer sleeve with respect to the first sleeve. It becomes possible to cope with a larger amount of expansion / contraction between the ends of adjacent tubular bodies, and it is possible to cope with a large amount of expansion / contraction for a limited length.

The schematic diagram which shows 1st Embodiment of this invention. The schematic diagram which shows 2nd Embodiment of this invention. The figure which shows 3rd Embodiment of this invention and shows the state which has not expanded-contracted and eccentrically made to the axial direction between piping. The end view which shows 3rd Embodiment of this invention. The figure which shows 3rd Embodiment of this invention and shows the state which has eccentricity between piping. The figure which shows 3rd Embodiment of this invention and shows the state which has expansion-contraction and eccentricity in an axial direction between piping. FIG. 7 is a perspective view corresponding to FIG. 6. The figure which shows 4th Embodiment of this invention.

Embodiments of the present invention will be described below with reference to the drawings.
A first embodiment of the present invention will be described with reference to FIG. In FIG. 1, the symbol C indicates the axis of the repairable expansion / contraction flexible joint 3, the first pipe 1 is connected to, for example, a building of a hydroelectric power plant, and the first pipe 1 and the second pipe 2 are formed in a tubular shape. The first pipe 1, the second pipe 2, and the telescopic flexible joint 30 are embedded in the sea or in the ground.

  The expansion / contraction flexible joint 30 includes a first end pipe 31 attached to the first pipe 1, a second end pipe 32 attached to the second pipe 2, a connection sleeve 35, and sealing materials 33 and 34. ing. A gap is formed between the connection sleeve 35 and the outer peripheral surface of the first end pipe 31 and the outer peripheral surface of the second end pipe 32 via seal members 33 and 34, and the first pipe 1 and the gap are formed by the gap. The second pipe 2 absorbs the amount of eccentricity not only in the axial direction but also in the direction perpendicular to the axial direction.

  Here, assuming that the expansion / contraction flexible joint 30 is damaged by an earthquake or the like and the normal sealed connection relationship between the first pipe 1 and the second pipe 2 is not maintained, the damaged expansion / contraction flexible joint 30 Let us consider that the repaired expansion / contraction flexible joint 3 is restored to a normal sealed connection relationship between the first pipe 1 and the second pipe 2 while leaving 30 broken without being removed.

  The sleeve 5 of the repairable expansion / contraction flexible joint 3 includes a tubular first sleeve 6 into which an end portion of the first pipe 1 and an end portion of the second pipe 2 are inserted, and a tubular portion provided outside the first sleeve 6. The outer sleeve 7 is provided. The outer sleeve 7 is movable relative to the first sleeve 6 in the axial direction between an overlapped state initially set with respect to the first sleeve 6 and a state in which the overlap is released. In the present embodiment, the outer sleeve 7 is composed of a single outer configuration sleeve disposed outside the first sleeve 6.

  The repairable expansion / contraction flexible joint 3 includes a first sealing material 17, a second sealing material 18, and a third sealing material 18.

  The first sealing material 17 is a liquid between the inner peripheral surface of the first sleeve 6 and the outer peripheral surface of the end of the first pipe 1 so that the first sleeve 6 and the first pipe 1 can move relative to each other in the axial direction. Seal tightly. The first sealing material 17 forms a small gap between the inner peripheral surface of the first sleeve 6 and the outer peripheral surface of the end portion of the first pipe 1, and the first sleeve 6 is within a range allowed by this gap. And the first pipe 1 are liquid-tightly sealed so as to be movable eccentrically.

  The second sealing material 18 provides a liquid-tight seal between the inner peripheral surface of the outer sleeve 7 and the outer peripheral surface of the second pipe 2 so that the outer sleeve 7 and the second pipe 2 can move relative to each other in the axial direction. The second sealing material 18 forms a small gap between the inner peripheral surface of the outer sleeve 7 and the outer peripheral surface of the second pipe 2, and the outer sleeve 7 and the second pipe 2 are within a range allowed by this gap. And liquid-tight seal so that they can move eccentrically. As shown in FIG. 1, in order to hold the second sealing material 18 between the inner peripheral surface of the outer sleeve 7 and the outer peripheral surface of the second pipe 2, the second sealing material 18 is provided at the end of the outer sleeve 7. A bent portion is formed so as to surround the.

  The third sealing material 19 performs a fluid-tight seal between the outer peripheral surface of the first sleeve 6 and the inner peripheral surface of the outer sleeve 7 so that the first sleeve 6 and the outer sleeve 7 can move relative to each other in the axial direction. Further, the third seal material 19 forms a small gap between the outer peripheral surface of the first sleeve 6 and the inner peripheral surface of the outer sleeve 7, and the first sleeve 6 and the outer sleeve 7 are within a range allowed by this gap. Liquid-tightly seals in an eccentric manner. As shown in FIG. 1, the third seal material 19 is held between the outer peripheral surface of the first sleeve 6 and the inner peripheral surface of the outer sleeve 7 so that the third seal member 19 is provided on the outer peripheral surface of the first sleeve 6. Grooves for holding the material 19 are formed.

  Next, the 1st sealing material 17, the 2nd sealing material 18, and the 3rd sealing material 19 are demonstrated. In FIG. 1, the first sealing material 17, the second sealing material 18, and the third sealing material 19 are displayed in an O-ring shape, but this is schematically shown. The second sealing material 18 and the third sealing material 19 have automatic sealing properties that are automatically self-deformed with respect to the internal pressure and the external pressure to ensure the sealing performance.

  Each of the first sleeve 6 and the outer sleeve 7 is composed of a plurality of elements along the axis C divided in the circumferential direction, and these plural elements are mutually connected by welding, bolts and nuts or the like at the repair site. It is fixed.

Next, the brake unit 13 will be described.
The brake unit 13 limits the relative movement in the axial direction of the outer sleeve 7 with respect to the first sleeve 6. When the repairable expansion / contraction flexible joint 3 is set at the installation location, the first sleeve 6 and the outer sleeve 7 are initially set so as to be the most overlapped with each other.

  A fluid flows inside the repairable expansion / contraction flexible joint 3 that connects the first pipe 1 and the second pipe 2, and as shown in FIG. 1, a force per unit area is applied to the inner wall surface of the first sleeve 6. The external force F acts on the first sleeve 6 so as to move the first sleeve 6 in the direction opposite to the end of the first pipe 1. . Similarly, a pressure P, which is a force per unit area, acts on the inner wall surface of the outer sleeve 6, and the outer sleeve 7 is moved away from the end of the second pipe 2 by the pressure P. An external force F acts on the outer sleeve 7 so as to move in the partial direction.

  When the external force F does not exceed the predetermined threshold Fo, the brake unit 13 maintains the outer sleeve 7 in an overlapped state. When the external force F exceeds the predetermined threshold Fo, the brake unit 13 cancels the overlapped state and releases the first state. Allows the outer sleeve 7 to move relative to the sleeve 6.

  The brake unit 13 controls the relative movement of the outer sleeve 7 with respect to the first sleeve 6. A plurality of brake portions 13 are provided at equal intervals in the circumferential direction. The brake portion 13 has a rod-shaped fuse body 13a having a weak portion in the center portion that is laid between the outer sleeve 7 and the first sleeve 6, and the fuse body 13a connects the first sleeve 6 to the first pipe 1. When the external force F acting on the first sleeve 6 does not exceed the predetermined threshold value Fo so as to move in the opposite end direction, which is the direction opposite to the end portion of the sleeve, the outer sleeve 7 is laid between the first sleeve 6 and the first sleeve 6. When the external force F exceeds the predetermined threshold Fo, the external force F is received and cut. Similarly, in the fuse body 13a, the external force F acting on the second sleeve 7 does not exceed the predetermined threshold Fo so as to move the second sleeve 7 in the opposite end direction, which is the direction opposite to the end of the second pipe 2. In this case, the outer sleeve 7 and the first sleeve 6 are erected between the outer sleeve 7 and the first sleeve 6, and the external force F is cut when the external force F exceeds a predetermined threshold Fo.

  Here, the external force F is such that the outer sleeve 7 can be moved relative to the first sleeve 6 by the pressure P, which is a force per unit area acting on the inner wall surfaces of the first sleeve 6 and the outer sleeve 7. The sum of the acting forces is referred to, and this sum is compared with a predetermined threshold value Fo.

  Note that whether or not the braking action is released is determined as described above depending on whether the external force F is larger or smaller than the predetermined threshold value Fo. However, even if there is an acceptable ambiguous region having a width that includes the predetermined threshold value Fo. Good.

Next, the utility of the repairable expansion / contraction flexible joint 3 will be described.
Let S be the effective overlap length of the first sleeve 6 and the outer sleeve 7. The repairable expansion / contraction flexible joint 3 is disposed and repaired so as to cover the damaged expansion / contraction flexible joint 30 in a state where the first sleeve 6 and the outer sleeve 7 overlap each other. In this repaired initial state, the brake portion 13 is not cut unless a large earthquake or the like occurs, and the repairable expansion / contraction flexible joint 3 serves as one expansion / contraction flexible joint as the first pipe 1 and the second pipe 2. And When a large earthquake or the like occurs and the brake portion 13 is cut, the state in which the first sleeve 6 and the outer sleeve 7 overlap each other is released, and the repairable expansion / contraction flexible joint 3 has a length S without being suddenly damaged. It can function as one expansion-contraction flexible joint that can expand and contract between the length 2S.

Next, a second embodiment of the present invention will be described with reference to FIG.
In the case shown in FIG. 1, the first sleeve 6 is configured as a single sleeve straddling the end of the first pipe 1 and the end of the second pipe 2, but in the present embodiment, The 1 sleeve 6 is comprised from the 1st sleeve part 6a and the 2nd sleeve part 6b which are two elements assembled as a mutually separate body. The outer peripheral surface of the first sleeve portion 6a and the outer peripheral surface of the second sleeve portion 6b are provided so as to form substantially the same peripheral surface. The third sealing material 19 is disposed on the first sleeve portion 6a. A sealing material 20 is provided between the outer surface of the second sleeve portion 6 b and the inner surface of the outer sleeve 7. Further, the second sleeve portion 6 b and the outer sleeve 7 are connected by a bolt and nut 21.

  As in the case of the first embodiment, each of the first sleeve 6 and the outer sleeve 7 is composed of a plurality of elements divided along the axis C, and the first sleeve constituting the first sleeve 6. Each of the part 6a and the second sleeve part 6b is divided into a plurality of parts, and these elements are fixed to each other by welding, bolts and nuts or the like at the repair site.

  Here, the first pipe 1 and the second pipe 2 are not necessarily circular in cross section, and generally, they may be eccentric and distorted in different shapes.

  In the case of the present embodiment, the first sleeve 6 is composed of a first sleeve portion 6a and a second sleeve portion 6b that are assembled separately from each other, so that the first sleeve portion 6a is configured in the circumferential direction. A plurality of elements can be assembled to match the eccentric shape of the first pipe 1 without depending on the eccentric shape of the second pipe 2, and the plurality of elements constituting the second sleeve portion 6b in the circumferential direction can be assembled. The second pipe 2 can be assembled without depending on the eccentric shape of the first pipe 1 according to the eccentric shape of the second pipe 2. As a result, it is possible to smoothly perform repair work at the repair site.

next. A third embodiment of the present invention will be described with reference to FIGS. The first sleeve 6 and the outer sleeve 7 are composed of a plurality of members divided in the radial direction, and these members are assembled to each other by bolts and nuts or welding.
This embodiment shows a repairable expansion / contraction flexible joint 3 that functions as the actual device of the second embodiment schematically shown in FIG.

  FIG. 3 is a side view of the repairable expansion / contraction flexible joint 3 according to the present embodiment. As in the case of the second embodiment shown in FIG. 2, the second sleeve portion 6b and the outer sleeve 7 are mutually fixed at the repair site so as to surround the expansion / contraction flexible joint 30 to be repaired by the bolt / nut 21. Connected.

  Also, in the present embodiment, unlike the second embodiment, the outer sleeve 7 itself is composed of a long member element 7a at the center and a short member element 7b at the right end, and the member elements 7a and 7b. Are connected by bolts and nuts 21a with the sealant 20a in between. The outer sleeve 7 functions integrally after being assembled by the member element 7a and the member element 7b.

  4 is an end view seen from the right side of FIG.

  FIG. 5 shows that when the first pipe 1 and the second pipe 2 repaired and connected by the repair expansion / contraction flexible joint 3 are eccentric to each other, the repair expansion / contraction flexible joint 3 keeps the eccentricity sealed to cope with it. FIG.

  FIG. 6 shows the repairable expansion / contraction flexible joint 3 in the case where the first pipe 1 and the second pipe 2 further extend in addition to the situation shown in FIG. In FIG. 6, the length by which the first pipe 1 and the second pipe 2 extend is increased, and the expansion / contraction flexible joint 30 is divided into a first part 30a and a second part 30b. The repair expansion / contraction flexible joint 3 extends to a length of 2S, and copes with the expansion between the first pipe 1 and the second pipe 2 while maintaining hermeticity. FIG. 7 is a perspective view showing the situation shown in FIG.

  According to this embodiment, the same effect as that of the first embodiment can be obtained. Further, in addition to the first sleeve 6 being composed of the first sleeve portion 6a and the second sleeve portion 6b assembled separately from each other, the outer sleeve 7 is composed of the member element 7a and the member element 7b. Therefore, in addition to being able to be assembled according to the eccentric shape of the second pipe 2, it is possible to repair appropriately according to the situation of the repair site such as distortion of the first pipe 1.

Next, a fourth embodiment of the present invention will be described.
In the first to third embodiments described above, the outer sleeve 7 is composed of a single outer configuration sleeve disposed outside the first sleeve 6, whereas in the present embodiment, the outer sleeve 7 is A plurality of constituent sleeves arranged to overlap each other, for example, two constituent sleeves, an inner constituent sleeve 7A and an outer constituent sleeve 7B provided outside the inner constituent sleeve 7A.

  Here, an example of two constituent sleeves 7A and 7B is shown as a plurality of constituent sleeves of the outer sleeve 7, but three or more constituent sleeves may be used.

  Between the inner configuration sleeve 7A and the outer configuration sleeve 7B, there is provided an outer brake portion 14 that restricts the relative movement of the outer configuration sleeve 7B in the axial direction with respect to the inner configuration sleeve 7A.

  Further, a fourth seal material 19a is provided between the outer peripheral surface of the inner constituent sleeve 7A and the inner peripheral surface of the outer constituent sleeve 7B. The fourth sealing material 19a is liquid-tightly sealed between the outer peripheral surface of the inner constituent sleeve 7A and the inner peripheral surface of the outer constituent sleeve 7B so that the inner constituent sleeve 7A and the outer constituent sleeve 7B can move relative to each other in the axial direction. .

  According to the present embodiment, the outer sleeve 7 is composed of the inner constituent sleeve 7A and the outer constituent sleeve 7B that are arranged so as to overlap each other, so that the outer sleeve 7 can extend in the axial direction with a length of 3S.

  Further, by configuring the outer sleeve 7 with three or more n sleeves arranged so as to overlap each other, it is possible to extend in the axial direction because of the length of nS. As an example, the brake portion having the fuse body 13a has been described. However, the present invention is not limited to this, and the brake portion may be configured by a friction body, for example, and the axial movement of the outer sleeve relative to the first sleeve can be controlled. Other forms may be used as long as they can be limited.

DESCRIPTION OF SYMBOLS 1 1st piping 2 2nd piping 3 Expansion / contraction flexible joint 5 Sleeve 6 1st sleeve 6a 1st sleeve part 6b 2nd sleeve part 7 Outer sleeve 7A Inner structure sleeve 7B Outer structure sleeve 13 Brake part 13a Fuse body 14 Outer brake part 17 1st sealing material 18 2nd sealing material 19 3rd sealing material 19a 4th sealing material F External force Fo Predetermined threshold value

Claims (6)

A repair expansion / contraction flexible joint that connects the first pipe and the second pipe connected by a joint in a freely stretchable manner,
A first sleeve into which an end of the first pipe and an end of the second pipe are inserted;
An outer sleeve provided on the outer side of the first sleeve so as to be movable relative to the first sleeve in an axial direction between a state of being overlapped with the first sleeve and a state of being released from the overlap;
A first sealing material that provides a fluid-tight seal between the inner peripheral surface of the first sleeve and the outer peripheral surface of the end portion of the first pipe so that the first sleeve and the first pipe are relatively movable in the axial direction. When,
A second sealing material that provides a fluid-tight seal between the inner peripheral surface of the outer sleeve and the outer peripheral surface of the second pipe so that the outer sleeve and the second pipe are relatively movable in the axial direction;
A third sealing material that provides a liquid-tight seal between the outer peripheral surface of the first sleeve and the inner peripheral surface of the outer sleeve so that the first sleeve and the outer sleeve are relatively movable in the axial direction;
The joint is broken and acts on the first sleeve so as to move the first sleeve toward the opposite end of the first pipe, and moves the outer sleeve toward the opposite end of the second pipe. When the external force acting on the outer sleeve does not exceed a predetermined threshold value, the outer sleeve is maintained in the overlapped state , and when the external force exceeds the predetermined threshold value, the overlapped state is released and applied to the first sleeve. A repairable expansion / contraction flexible joint, comprising: a brake portion that restricts relative movement of the outer sleeve in the axial direction with respect to the first sleeve, which enables relative movement of the outer sleeve. The first sleeve is divided into a first sleeve portion attached to an end portion of the first pipe and a second sleeve portion attached to an end portion of the second pipe. The repairable expansion / contraction flexible joint according to Item 1. The repairable expansion / contraction flexible joint according to claim 1, wherein the outer sleeve is formed of a single outer configuration sleeve disposed on the outer side of the first sleeve. The outer sleeve is composed of a plurality of constituent sleeves arranged to overlap each other,
An axial relative movement of the outer configuration sleeve with respect to the inner configuration sleeve is performed between an inner configuration sleeve located on the inner side of the plurality of configuration sleeves and an outer configuration sleeve provided outside the inner configuration sleeve. The repairable expansion / contraction flexible joint according to claim 1, further comprising an outer brake portion to be limited. The brake portion includes a fuse body that is laid between the outer sleeve and the first sleeve, and the fuse body is configured such that the outer sleeve and the first sleeve when the external force does not exceed the predetermined threshold value. The repairable expansion / contraction flexible joint according to claim 1, wherein the repairable expansion / contraction flexible joint is cut by receiving the external force when the external force exceeds the predetermined threshold. The first seal material forms a first gap between an inner peripheral surface of the first sleeve and an outer peripheral surface of the joint, and the second seal material and the third seal material are formed on the outer periphery of the first sleeve. Forming a second gap between the surface and the inner peripheral surface of the outer sleeve;
2. The first gap and the second gap are set to allow a predetermined range of bending movement between the first pipe and the second pipe. Repair expansion and contraction flexible joint.

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