Double tube connection structure, connection system, and seal material replacement method for double tube connection structure

Abstract

To improve workability when performing work for connecting or disconnecting two double pipes.SOLUTION: A double pipe connection structure comprises: a first double pipe including a first inner pipe, a first inside flange, a first outer pipe exposing the first inner pipe between itself and the first inside flange, and a first outside flange; a second double pipe including a second inner pipe, a second inside flange, a second outer pipe exposing the second inner pipe between itself and the second inside flange, and a second outside flange; and a sleeve capable of moving in a pipe axis direction of the first inside flange and the second inside flange between a connection position at which it is connected to both the first outside flange and the second outside flange while covering the first inside flange and the second inside flange, and a standby position at which the first inside flange and the second inside flange are exposed. The first outer pipe or the second outer pipe includes a bellows for absorbing positional errors among the first outside flange, the second outside flange, and the sleeve, and thermal contraction of the first inner pipe and the second inner pipe.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a double-tube connection structure, a connection system, and a method for replacing a sealing material of a double-tube connection structure.

Background Art

[0002] Patent Document 1 discloses a connection structure that enables connection between two double tubes. The connection structure of Patent Document 1 includes a first double tube and a second double tube. The first double tube and the second double tube each include an inner tube and an outer tube that exposes the vicinity of the tip of the inner tube. A sleeve is attached to the second double tube. The sleeve slides between a standby position that exposes the tip of the inner tube of the second double tube and a connection position that is fastened to the outer tube of the first double tube and the outer tube of the second double tube. Further, the sleeve has a bellows for absorbing an axial deviation between the outer tube of the first double tube and the outer tube of the second double tube. When connecting and disconnecting the first double tube and the second double tube, the sleeve is slid between the standby position and the connection position.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A connection structure that improves workability is desired for the sleeve that needs to be moved during the operation of connecting or disconnecting the first double tube and the second double tube.

[0005] Therefore, an object of the present disclosure is to provide a double-tube connection structure, a connection system, and a method for replacing a sealing material of a double-tube connection structure that can improve workability when performing an operation of connecting or disconnecting two double tubes.

Means for Solving the Problems

[0006] In order to solve the above problems, a double-tube connection structure according to one aspect of the present disclosure includes a first inner tube, a first inner flange protruding from the tip of the first inner tube, a first outer tube that exposes the first inner tube between the first inner flange, and a first outer flange protruding from the first outer tube, a first double tube; a second inner tube, a second inner flange protruding from the tip of the second inner tube and connected to the first inner flange, a second outer tube that exposes the second inner tube between the second inner flange, and a second outer flange protruding from the second outer tube, a second double tube; a sleeve that is movable in the axial direction of the tube axis between the first inner flange and the second inner flange, and is connected to both the first outer flange and the second outer flange in a state of covering the first inner flange and the second inner flange; and the first outer tube or the second outer tube includes bellows that absorb mutual positional errors of the first outer flange, the second outer flange, and the sleeve, and thermal shrinkage of the first inner tube and the second inner tube.

[0007] The double-tube connection structure according to another aspect of the present disclosure includes a first inner tube, a first inner flange protruding from the tip of the first inner tube, a first outer tube exposing the first inner tube between the first inner flange, and a first outer flange protruding from the first outer tube. A first double tube including a first outer flange; a second inner tube; a second inner flange protruding from the tip of the second inner tube and connected to the first inner flange; and the second inner tube between the second inner flange. A second double tube including a second outer tube exposing the second outer tube and a second outer flange protruding from the second outer tube; and a connection position connected to both the first outer flange and the second outer flange in a state where the first inner flange and the second inner flange are covered. A sleeve that is movable in the axial direction of the tube between the first inner flange and the second inner flange and a standby position that exposes the first inner flange and the second inner flange, and the first outer flange is viewed in the axial direction of the tube. A sleeve including a cylindrical main body portion that encloses the sleeve, and an annular portion that protrudes inward from the main body portion and faces the first outer flange in a direction perpendicular to the axial direction of the tube when the sleeve is in the connection position; When the sleeve is in the connection position, an annular ring plate that overlaps both the annular portion and the first outer flange when viewed in the axial direction of the tube and indirectly connects the annular portion and the first outer flange; and the ring plate and the annular portion. An annular first sealing material sandwiched in the axial direction, and an annular second sealing material sandwiched in the axial direction by the ring plate and the first outer flange.

[0008] The connection system according to one aspect of the present disclosure includes the double-tube connection structure and an assist device that assists the movement of the sleeve between the standby position and the connection position. The assist device is a rail that extends in a direction parallel to the axial direction of the tube above the double-tube connection structure. A slider supported by the rail and slidable in the axial direction of the tube, and a suspension connection member that connects the slider and the sleeve.

[0009] A method for replacing a sealing material of a double pipe connection structure according to an aspect of the present disclosure includes a first inner pipe, a first inner flange protruding from a tip of the first inner pipe, a first outer pipe exposing the first inner pipe between the first inner flange, and a first outer flange protruding from the first outer pipe. A first double pipe including a second inner pipe, a second inner flange protruding from a tip of the second inner pipe and connected to the first inner flange, a second outer pipe exposing the second inner pipe between the second inner flange, and a second outer flange protruding from the second outer pipe. A second double pipe, a connection position connected to both the first outer flange and the second outer flange in a state of covering the first inner flange and the second inner flange, and a standby position exposing the first inner flange and the second inner flange. A sleeve movable in the axial direction of the pipe between the first inner flange and the second inner flange, and an annular sealing material that abuts on the first outer flange and seals between the sleeve and the first outer flange. In a double pipe connection structure including: A method for replacing a sealing material of a double pipe connection structure for replacing the sealing material, wherein the fastening of the sleeve to the first double pipe and the second double pipe is released, and the sleeve at the connection position is moved away from the second double pipe in the axial direction of the pipe to expose the first inner flange and the second inner flange. The sleeve is further moved away from the second double pipe in the axial direction of the pipe to expose the first outer flange, and the sealing material is removed from the first outer flange and replaced with a new sealing material.

Effect of the Invention

[0010] According to the present disclosure, it is possible to provide a double pipe connection structure, a connection system, and a method for replacing a sealing material of a double pipe connection structure that can improve workability when connecting or separating two double pipes.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0012] Hereinafter, embodiments will be described with reference to the drawings.

[0013] <First Embodiment> FIG. 1 is a cross-sectional view of a double pipe connection structure 1A according to the first embodiment. The double pipe connection structure 1A described in this embodiment is a connection structure for connecting a device 2 and a fluid supply source that supplies a low-temperature fluid to the device 2. The low-temperature fluid is a low-temperature liquefied gas or vaporized gas. In this example, the low-temperature fluid is liquefied hydrogen.

[0014] (Configuration of the double pipe structure) The double pipe connection structure 1A includes a first double pipe 10, a second double pipe 20, and a sleeve 40. In this embodiment, the second double pipe 20 is a part of the device 2, and the first double pipe 10 is the tip of a pipe extending from the fluid supply source.

[0015] In the following description, for convenience, the connection direction between the first double pipe 10 and the second double pipe 20 in the double pipe connection structure 1A, that is, the direction in which the center lines of the first double pipe 10 and the second double pipe 20 extend in the vicinity of the connection portion, is referred to as the pipe axis direction F. The pipe axis direction F can also be referred to as the extending direction, connection direction, or axial direction of the first double pipe 10 and the second double pipe 20. In this embodiment, the pipe axis direction F substantially coincides with the horizontal direction. Also, the direction perpendicular to the center lines of the first double pipe 10 and the second double pipe 20 is referred to as the radial direction.

[0016] The first double pipe 10 has a first inner pipe 11, a first inner flange 12 protruding radially outward from the first inner pipe 11, a first outer pipe 13, and a first outer flange 14 protruding radially outward from the first outer pipe 13.

[0017] The first inner pipe 11 allows a low-temperature fluid to flow through. The first inner flange 12 is arranged at the tip of the first inner pipe 11. A plurality of through holes arranged at intervals along the circumferential direction are arranged in the first inner flange 12. A bolt 51 is inserted through each through hole.

[0018] The tip of the first outer pipe 13 is located at a position away from the first inner flange 12. That is, the first outer pipe 13 exposes the first inner pipe 11 between it and the first inner flange 12. This is to ensure a space necessary for the attachment and fastening of the bolt 51 and a nut 52 described later.

[0019] The first outer flange 14 is arranged at the tip of the first outer pipe 13. A plurality of screw holes arranged at intervals along the circumferential direction are arranged on the contact surface of the first outer flange 14 with a first annular portion 42 described later. Each screw hole is a blind hole that does not penetrate the first outer flange 14. The threaded portion of a bolt 53 engages with each screw hole.

[0020] The first outer tube 13 has an expansion tube 30. In other words, a part of the first outer tube 13 is constituted by the expansion tube 30. The expansion tube 30 has a bellows 31, and a first cover 32 and a second cover 33 that cover the periphery of the bellows 31 and protect the bellows 31. The bellows 31 enables displacement of a portion 13a (hereinafter referred to as the first portion 13a) of the first outer tube 13 that is located on the side opposite to the first outer flange 14 with respect to the bellows 31, with respect to a portion 13b (hereinafter referred to as the second portion 13b) between the bellows 31 and the first outer flange 14 in the first outer tube 13. For this reason, the bellows 31 enables displacement of the first outer flange 14 so as to come to a predetermined position with respect to a second outer flange 24 described later. More specifically, the bellows 31 absorbs the mutual positional errors of the first outer flange 14, the second outer flange 24, and the sleeve 40 so that the sleeve 40 is fastened to the first outer flange 14 and the second outer flange 24 described later (in other words, so that the positions of the mutual through holes or screw holes match). Further, the bellows 31 absorbs the thermal shrinkage of the first inner tube 11 and the second inner tube 21 as well.

[0021] The first cover 32 and the second cover 33 are relatively displaceable with respect to each other. The first cover 32 is fixed to the first portion 13a of the first outer tube 13, and the second cover 33 is fixed to the second portion 13b of the first outer tube 13. At least one of the first cover 32 and the second cover 33 includes a cylindrical portion that overlaps the bellows 31 in the radial direction.

[0022] The first double tube 10 includes a closing member 15 that closes the space S1 between the first inner tube 11 and the first outer tube 13. The space S1 closed by the closing member 15 is evacuated by, for example, a pump (not shown) and thus is in a vacuum state.

[0023] The closing member 15 connects the first inner tube 11 and the first outer tube 13 in the radial direction. More specifically, the closing member 15 connects to the first outer tube 13 on the side opposite to the side where the first outer flange 14 is located with respect to the bellows 31 in the tube axis direction F. Further, the closing member 15 connects to the first inner tube 11 between the bellows 31 and the first inner flange 12 in the tube axis direction F.

[0024] In this embodiment, the closing member 15 includes two ring plates 15a and 15b, and a cylinder 15c connecting the two ring plates 15a and 15b. The ring plate 15a protrudes radially inward from the first outer tube 13 on the side opposite to the side where the first outer flange 14 is located with respect to the bellows 31 in the tube axis direction F. The ring plate 15b protrudes radially outward from the first inner tube 11 between the ring plate 15a and the first inner flange 12 in the tube axis direction F, more specifically, between the bellows 31 and the first inner flange 12. The cylinder 15c extends in the tube axis direction F between the first inner tube 11 and the first outer tube 13. The cylinder 15c connects the inner peripheral edge of the ring plate 15a and the outer peripheral edge of the ring plate 15b in the tube axis direction F.

[0025] In this embodiment, the device 2 includes a reservoir for storing the cryogenic fluid in a cryogenic state. Specifically, the device 2 includes a second double tube 20, an inner tank 3 for storing the cryogenic fluid introduced through the second double tube 20, and an outer tank 4 covering the inner tank 3.

[0026] The second double tube 20, which is the double tube on the device 2 side, has a second inner tube 21, a second inner flange 22 protruding radially outward from the tip of the second inner tube 21, a second outer tube 23, and a second outer flange 24 protruding radially outward from the tip of the second outer tube 23.

[0027] The base end of the second inner tube 21 (the end opposite to the second inner flange 22) is connected to the inlet 3a of the inner tank 3. The base end of the second outer tube 23 (the end opposite to the second outer flange 24) is connected to the opening edge 4a of the outer tank 4. In this embodiment, the space between the inner tank 3 and the outer tank 4 is connected to the space between the second inner tube 21 and the second outer tube 23. Therefore, the space between the inner tank 3 and the outer tank 4 and the space between the second inner tube 21 and the second outer tube 23 are simultaneously evacuated by a pump (not shown).

[0028] However, the device 2 may be provided with a closing member that closes the space between the inner tank 3 and the outer tank 4. That is, the space between the inner tank 3 and the outer tank 4 and the space near the second inner flange 22 may be partitioned by the closing member. In this case, the space between the inner tank 3 and the outer tank 4 is evacuated separately from the space near the second inner flange 22. For example, the closing member that closes the space between the inner tank 3 and the outer tank 4 may be provided so as to connect the opening edge portion 4a of the outer tank 4 and the second inner pipe 21.

[0029] The second inner pipe 21 allows a cryogenic fluid to flow through. The second inner flange 22 is disposed at the tip of the second inner pipe 21. A plurality of through holes arranged at intervals along the circumferential direction are disposed on the second inner flange 22. A bolt 51 is inserted through each through hole.

[0030] The tip of the second outer pipe 23 is located at a position away from the second inner flange 22. That is, the second outer pipe 23 exposes the second inner pipe 21 between it and the second inner flange 22. This is to ensure the space necessary for the attachment and fastening of the bolt 51 and the nut 52 described later.

[0031] The second outer flange 24 is disposed at the tip of the second outer pipe 23. A plurality of through holes arranged at intervals along the circumferential direction are disposed on the second outer flange 24. A bolt 54 is inserted through each through hole.

[0032] The first inner flange 12 of the first double pipe 10 and the second inner flange 22 of the second double pipe 20 are fastened to each other by bolts 51 and nuts 52 via a sealing material 61 that seals between them. As described above, the first inner flange 12 and the second inner flange 22, and the first inner pipe 11 and the second inner pipe 21 are exposed near these flanges 12, 22. These exposed portions are covered by the sleeve 40.

[0033] The sleeve 40 is fastened to both the first outer flange 14 of the first double tube 10 and the second outer flange 24 of the second double tube 20. Thereby, the sleeve 40 forms a sealed space S2 around the first double tube 10 and the second double tube 20 between the first outer flange 14 and the second outer flange 24.

[0034] In the present embodiment, the sleeve 40 is attached to the first double tube 10 so as to be movable in the tube axis direction F of the first double tube 10. The sleeve 40 is connected to both the first outer flange 14 and the second outer flange 24 in a state of covering the first inner flange 12 and the second inner flange 22, and is movable between a connection position where the first inner flange 12 and the second inner flange 22 are exposed and a standby position (see FIG. 2) where the first inner flange 12 and the second inner flange 22 are exposed.

[0035] The sleeve 40 includes a cylindrical main body portion 41, a first annular portion 42, and a second annular portion 43. The first annular portion 42 projects radially inward from the first end portion (the end portion on the side of the first double tube 10) of the main body portion 41 in the tube axis direction F. The second annular portion 43 projects radially outward from the second end portion (the end portion on the side of the second double tube 20) of the main body portion 41 in the tube axis direction F. That is, the first annular portion 42 is smaller than the second annular portion 43.

[0036] In a state where the sleeve 40 is in the connection position, the cylindrical main body portion 41 covers the first inner flange 12 and the second inner flange 22. That is, in a state where the sleeve 40 is in the connection position, when viewed in the radial direction, the cylindrical main body portion 41 is at a position overlapping the first inner flange 12 and the second inner flange 22.

[0037] The main body portion 41 encloses the first outer flange 14 when viewed in the tube axis direction F. That is, the main body portion 41 is located radially outward of the first outer flange 14. In other words, the inner diameter of the main body portion 41 is larger than the outer diameter of the first outer flange 14. In a state where the sleeve 40 is in the connection position, the first outer flange 14 is accommodated in the sleeve 40. The inner diameter of the main body portion 41 and the inner diameter of the second outer tube 23 are substantially the same. The first outer flange 14 is smaller than the second outer flange 24.

[0038] The first annular portion 42 faces the first outer flange 14 in the tube axis direction F. A plurality of through holes arranged at intervals along the circumferential direction are disposed in the first annular portion 42. A bolt 53 is inserted through each through hole. The second annular portion 43 faces the second outer flange 24 in the tube axis direction F. A plurality of through holes arranged at intervals along the circumferential direction are disposed in the second annular portion 43. A bolt 54 is inserted through each through hole.

[0039] The position of the first annular portion 42 with respect to the first outer flange 14 in the tube axis direction F and the position of the second annular portion 43 with respect to the second outer flange 24 in the tube axis direction F are the same as each other. In the present embodiment, the first annular portion 42 is on the side where the bellows 31 is located in the tube axis direction F with respect to the first outer flange 14, and the second annular portion 43 is also on the side where the bellows 31 is located in the tube axis direction F with respect to the second outer flange 24.

[0040] An annular sealing material 62 is sandwiched between the first annular portion 42 and the first outer flange 14 in the tube axis direction F. The annular sealing material 62 seals between the first annular portion 42 and the first outer flange 14. The first annular portion 42 is in surface contact with the surface of the first outer flange 14 on the side opposite to the second outer flange 24 with the sealing material 62 interposed therebetween. An annular groove 64 (see FIG. 3) for disposing the sealing material 62 is formed on one or both of the abutting surfaces of the first annular portion 42 and the first outer flange 14. It is preferable that the annular groove 64 is only on the abutting surface of the first outer flange 14 among the abutting surfaces of the first annular portion 42 and the first outer flange 14.

[0041] The second annular portion 43 and the second outer flange 24 sandwich an annular sealing material 63 in the pipe axis direction F. The annular sealing material 63 seals between the second annular portion 43 and the second outer flange 24. The second annular portion 43 is in surface contact with the surface of the second outer flange 24 on the first outer flange 14 side with the sealing material 63 interposed therebetween. An annular groove for arranging the sealing material 63 is formed on one of the abutting surfaces of the second annular portion 43 and the second outer flange 24. It is preferable that the annular groove is only on the abutting surface of the second outer flange 24 among the abutting surfaces of the second annular portion 43 and the second outer flange 24 with each other.

[0042] The types of the sealing materials 61, 62, and 63 can be different from each other. For example, the sealing material 61 is for extremely low temperatures, but the sealing materials 62 and 63 do not have to be for extremely low temperatures. Further, as will be described later, since the sealing material 62 needs to be moved in the pipe axis direction F so as to cross over the first outer flange 14 during replacement, it has elasticity. For example, the sealing material 62 may be a rubber O-ring. On the other hand, the sealing materials 61 and 63 do not have to have elasticity. For example, the sealing materials 61 and 63 may be stainless steel O-rings.

[0043] The first annular portion 42 of the sleeve 40 and the first outer flange 14 of the first double pipe 10 are fastened to each other by bolts 53 via a sealing material 62 that seals between them. The bolts 53 engage with the screw holes of the first outer flange 14. The second annular portion 43 of the sleeve 40 and the second outer flange 24 of the second double pipe 20 are fastened to each other by bolts 54 and nuts 55 via a sealing material 63 that seals between them.

[0044] (Method for connecting or separating two double pipes) Next, a method for separating the first double pipe 10 and the second double pipe 20 using the connection structure 1A of the present embodiment will be described with appropriate reference to FIGS. 1 and 2. As shown in FIG. 1, in a state where the sleeve 40 is in the connection position, the first inner flange 12 and the second inner flange 22 are covered. Further, in a state where the sleeve 40 is in the connection position, the sleeve 40 covers the first outer flange 14.

[0045] In order to separate the first double tube 10 and the second double tube 20, first, the fastening of the sleeve 40 to the first double tube 10 and the second double tube 20 is released. That is, the bolts 53 and 54 are removed to release the connection of the sleeve 40 to the first double tube 10 and the second double tube 20. Then, the sleeve 40 is moved from the connection position to the standby position.

[0046] FIG. 2 is a cross-sectional view of the double tube connection structure 1A with the sleeve 40 moved to the standby position. In the present embodiment, the standby position is between the bellows 31 and the first outer flange 14 in the tube axis direction F. The sleeve 40 at the connection position is moved away from the second double tube 20 in the tube axis direction F to expose the first inner flange 12 and the second inner flange 22. Further, the sleeve 40 is moved away from the second double tube 20 in the tube axis direction F to expose the first outer flange 14 accommodated in the sleeve 40 as well (see the two-dot chain line in FIG. 2).

[0047] The sleeve 40 in the standby position is supported by the second portion 13b between the bellows 31 and the first outer flange 14 in the first outer tube 13. For example, as shown in FIG. 2, the sleeve 40 is supported by the first outer tube 13 in a state where a part of the inner peripheral surface of the main body portion 41 of the sleeve 40 (near the first annular portion 42) is in contact with the outer peripheral surface of the first outer tube 13.

[0048] With the sleeve 40 in the standby position, the bolt 51 is removed to release the connection between the first inner tube 11 of the first double tube 10 and the second inner tube 21 of the second double tube 20. Thus, the separation of the first double tube 10 and the second double tube 20, in other words, the separation of the device 2 from the pipe extending from the fluid supply source is completed.

[0049] Incidentally, since the method of connecting the first double pipe 10 and the second double pipe 20 is the reverse procedure of the method of separating the first double pipe 10 and the second double pipe 20 described above, the description thereof is omitted. After fastening the bolts 53 and 54 to connect the sleeve 40 to the first double pipe 10 and the second double pipe 20, the space S2 covered by the sleeve 40 is evacuated by a pump (not shown) to become a vacuum.

[0050] When the fastening of the sleeve 40 to the first double pipe 10 and the second double pipe 20 is released, the bellows 31 may be deformed by the gravity of the second portion 13b of the first outer pipe 13 or the first outer flange 14, and the second portion 13b of the first outer pipe 13 may be in a state of hanging downward. When the second portion 13b is hanging downward, in order to re-fasten the sleeve 40 to the first double pipe 10 and the second double pipe 20, it is necessary to lift the second portion 13b in the hanging state. In the present embodiment, the first double pipe 10 has a spacer 16 that suppresses the downward hanging of the second portion 13b of the first outer pipe 13 when the fastening of the sleeve 40 to the first double pipe 10 and the second double pipe 20 is released, so as to reduce the burden of lifting the second portion 13b during re-fastening.

[0051] The spacer 16 is disposed between the first outer tube 13 and the first inner tube 11, and between the bellows 31 and the first inner flange 12 in the tube axis direction F. The spacer 16 has heat insulation properties. In the present embodiment, the spacer 16 is disposed between the cylinder 15c of the closing member 15 in the radial direction and the first outer tube 13. The spacer 16 is fixed to the cylinder 15c, and when the second portion 13b of the first outer tube 13 sags due to the deformation of the bellows 31, the spacer 16 abuts against the second portion 13b. Note that the spacer 16 may be located closer to the first inner flange 12 than the ring plate 15b of the closing member 15. Further, the spacer 16 may be fixed not to the cylinder 15c but to the second portion 13b of the first outer tube 13, or may be fixed to a portion between the ring plate 15b and the first inner flange 12 of the first inner tube 11. Thus, even when the fastening of the sleeve 40 to the first double tube 10 and the second double tube 20 is released, the degree of sagging of the second portion 13b of the first outer tube 13 is within a certain range due to the spacer 16, so that the burden of lifting the second portion 13b when re-fastening the sleeve 40 to the first double tube 10 and the second double tube 20 can be reduced.

[0052] (Replacement of Sealing Material) In the present embodiment, the sleeve 40 in the standby position exposes the first outer flange 14. The reason for exposing the first outer flange 14 is to replace the sealing material 62, which is a consumable.

[0053] A method for removing the sealing material 62 from the first double tube 10 will be described with reference to FIGS. 3 and 4. FIG. 3 is an enlarged cross-sectional view of the vicinity of the tip of the first outer tube 13. FIG. 4 is a cross-sectional view taken along the line IV-IV of FIG. 3. In FIGS. 3 and 4, elements other than the first outer tube 13, the first outer flange 14, and the sealing material 62 (such as the first inner tube 11) are omitted.

[0054] An annular groove 64 for disposing the sealing material 62 is formed in the contact surface of the first outer flange 14 that contacts the first annular portion 42. When removing the sealing material 62, the sealing material 62 is moved so that the first outer flange 14 passes through the inside of the sealing material 62.

[0055] Specifically, in this embodiment, the outer diameter of the first outer flange 14 is designed to be sufficiently larger than the outer diameter of the first outer tube 13. Also, the sealing material 62 is disposed near the outer peripheral edge of the first outer flange 14 on the contact surface of the first outer flange 14. When removing the sealing material 62 from the first double tube 10, first, the sealing material 62 is removed from the groove 64, and a part of the sealing material 62 is brought close to or abutted against the outer peripheral surface of the outer tube 13. In this state, as shown by the two-dot chain line in FIG. 3, the portion of the sealing material 62 opposite to the portion brought close to or abutted against the outer tube 13 is moved so as to cross over the first outer flange 14. Then, the portion of the sealing material 62 brought close to or abutted against the outer tube 13 is moved so as to cross over the first outer flange 14. Thus, the sealing material 62 can be removed from the first double tube 10 and replaced with a new sealing material.

[0056] Note that the method of attaching the sealing material 62 to the first double tube 10 is the reverse procedure of the method of removing the sealing material 62 from the first double tube 10, so the description thereof is omitted.

[0057] (Function and effect) As described above, according to the double tube connection structure 1A according to this embodiment, the first outer tube 13, rather than the sleeve 40, has the expansion and contraction tube 30 including the bellows 31. That is, since it is not necessary to provide the bellows 31 with respect to the sleeve 40, the overall length of the sleeve 40 can be shortened, and the workability when connecting or separating the two double tubes 10 and 20 can be improved.

[0058] In addition, in the present embodiment, since the closing member 15 and the first outer tube 13 are connected on the side opposite to the side where the first outer flange 14 is located with respect to the bellows 31 in the tube axis direction F, even if the bellows 31 is displaced, the displacement of the bellows 31 can be prevented from being transmitted to the first inner tube 11 via the closing member 15. Further, since the closing member 15 and the first inner tube 11 are connected between the bellows 31 and the first inner flange 12 in the tube axis direction F, the exposed portion of the first inner tube 11 can be made as small as possible. That is, while preventing the displacement at the bellows 31 from being transmitted to the first inner tube 11, the exposed portion of the first inner tube 11 can be made as small as possible.

[0059] In addition, the overall length from the connection portion of the closing member 15 with the first inner tube 11 to the connection portion with the first outer tube 13 can be increased, and the heat of the low-temperature fluid flowing through the first inner tube 11 can be suppressed from being transmitted to the first outer tube 13 via the closing member 15.

[0060] In addition, in the present embodiment, the standby position of the sleeve 40 is between the bellows 31 and the first outer flange 14 in the tube axis direction F. For this reason, it is possible to design the sleeve 40 without considering the interference between the expansion and contraction tube 30 and the sleeve 40 when moving the sleeve 40 from the connection position to the standby position. Therefore, the size of the sleeve 40 can be made smaller than a configuration in which the bellows and the sleeve are arranged perpendicular to each other in the tube axis direction with the sleeve in the standby position.

[0061] In addition, in the present embodiment, when the sleeve 40 is in the connection position, the sleeve 40 covers the first outer flange 14, and when the sleeve 40 is in the standby position, the sleeve 40 exposes the first outer flange 14. For this reason, work can be performed on the first outer flange 14 with the sleeve 40 in the standby position. For example, it becomes easier to perform maintenance of the first outer flange 14 and replacement of consumables such as the sealing material 62 in the vicinity of the first outer flange 14.

[0062] Further, the first annular portion 42 and the first outer flange 14 are fastened to each other by a bolt 53 passing through the first annular portion 42 and engaging with the screw hole of the first outer flange 14. Since air does not flow into the sealed space S2 from the screw hole, which is a blind hole, it is easy to ensure the vacuum state of the sealed space S2.

[0063] <Second Embodiment> Next, the double-tube connection structure 1B according to the second embodiment will be described with reference to FIG. 5. For the second embodiment and the third embodiment described later, the parts different from the first embodiment will be mainly described, and the descriptions overlapping with the first embodiment will be omitted.

[0064] FIG. 5 is a cross-sectional view of the double-tube connection structure 1B according to the second embodiment. In FIG. 5, the sleeve 40 in the state of being moved to the standby position is shown by a broken line. In this embodiment, the structure of the first double tube 70 is different from the structure of the first double tube 10 of the first embodiment.

[0065] Specifically, the first double tube 70 includes a first inner tube 71, a first inner flange 72 protruding radially outward from the first inner tube 71, a first outer tube 73, and a first outer flange 74 protruding radially outward from the first outer tube 73. Since the structures of the first inner tube 71 and the first inner flange 72 are the same as those of the first inner tube 11 and the first inner flange 12, respectively, the description thereof will be omitted.

[0066] The tip of the first outer tube 73 is located at a position away from the first inner flange 72. That is, the first outer tube 73 exposes the first inner tube 71 between it and the first inner flange 72.

[0067] The first outer tube 73 includes a small-diameter portion 73a, a large-diameter portion 73b, and a stepped portion 73c. The small-diameter portion 73a and the large-diameter portion 73b are tubular, and the diameter of the large-diameter portion 73b is larger than the diameter of the small-diameter portion 73a. The large-diameter portion 73b is located on the side of the first outer flange 74 (i.e., the tip side) with respect to the small-diameter portion 73a. That is, the first outer flange 74 protrudes radially outward from the end of the large-diameter portion 73b in the tube axis direction F. The large-diameter portion 73b of the first outer tube 73 has the telescopic tube 30. The stepped portion 73c connects the small-diameter portion 73a and the large-diameter portion 73b. The stepped portion 73c is, for example, a ring-shaped plate.

[0068] The first double tube 70 includes a closing member 75 that closes the space S1 between the first inner tube 71 and the first outer tube 73. The closing member 75 connects the first inner tube 71 and the first outer tube 73 in the radial direction. The closing member 75 is the same as the closing member 15 of the first embodiment in terms of functional surface, but different in terms of structural surface.

[0069] Specifically, the closing member 75 includes a cylindrical portion 75a and one ring plate 75b that connects the cylindrical portion 75a and the first inner tube 71. The cylindrical portion 75a extends toward the second double tube 20 side from the end on the tip side of the small-diameter portion 73a, that is, from the connection portion of the small-diameter portion 73a with the stepped portion 73c. The diameter of the cylindrical portion 75a is the same as the diameter of the small-diameter portion 73a. The cylindrical portion 75a of the closing member 75 and the small-diameter portion 73a of the first outer tube 73 may be formed of one tube member. The ring plate 75b is located between the first inner flange 72 and the bellows 31 in the tube axis direction F. In the present embodiment, the ring plate 75b is located between the first outer flange 74 and the bellows 31 in the tube axis direction F.

[0070] A substantially cylindrical slide rail 76 is fixed to one or both of the first cover 32 and the second cover 33 of the telescopic tube 30. The slide rail 76 may be integrated with one or both of the first cover 32 and the second cover 33 of the telescopic tube 30. The central axis of the substantially cylindrical slide rail 76 coincides with the central axes of the first inner tube 71 and the first outer tube 73. The slide rail 76 is located radially outside the bellows 31.

[0071] The slide rail 76 guides the sleeve 40 from one of the connection position and the standby position to the other. For example, the slide rail 76 may include a plurality of bars or grooves that extend in the tube axis direction F and are arranged at intervals in the circumferential direction on the cylindrical circumferential surface. When the slide rail 76 has a configuration including a plurality of bars, the first annular portion 42 of the sleeve 40 may have a plurality of grooves into which the plurality of bars are respectively fitted. When the slide rail 76 has a configuration including a plurality of grooves, the first annular portion 42 of the sleeve 40 may have a plurality of protrusions that are respectively fitted into the plurality of grooves. The slide rail 76 can also serve to prevent the circumferential rotation of the sleeve 40 with respect to the first outer tube 73. The slide rail 76 may be provided with a stopper that restricts the movement range so that the sleeve 40 does not move beyond the range between the connection position and the standby position.

[0072] Also, as shown in FIG. 5, the slide rail 76 supports the sleeve 40 in the standby position. That is, the bellows 31 is located radially inward of the slide rail 76, and the sleeve 40 in the standby position is located radially outward of the slide rail 76. Thus, in the present embodiment, the sleeve 40 in the standby position overlaps the bellows 31 when viewed in the radial direction and is located outside the bellows 31 in the radial direction.

[0073] Also, in the present embodiment, the support device 80 is arranged near the double-tube connection structure 1B. The support device 80 supports the movement of the sleeve 40 between the standby position and the connection position. The double-tube connection structure 1B and the support device 80 constitute a connection system for connecting or separating two double tubes 70 and 20.

[0074] The support device 80 includes a rail 81 extending in a direction parallel to the pipe axis direction F, a slider 82 supported by the rail 81 and slidable in the pipe axis direction F, and a suspension connection member 83 connecting the slider 82 and the sleeve 40. The rail 81 and the slider 82 are located above the double pipe connection structure 1B. The suspension connection member 83 extends downward from the slider 82. The lower end of the suspension connection member 83 is connected to, for example, the main body 41 of the sleeve 40. The suspension connection member 83 is, for example, a chain or a rope.

[0075] The method of connecting or separating the two double pipes 70 and 20 in this embodiment is basically the same as that in the first embodiment. However, in this embodiment, when moving the sleeve 40 between the standby position and the connection position, the sleeve 40 is moved in a state where it is suspended and supported by the support device 80.

[0076] The support device 80 does not have to be a device permanently installed in the vicinity of the double pipe connection structure 1B. For example, it may be a temporary device that is installed only when performing the operation of connecting or separating the two double pipes 70 and 20. When the support device 80 is a temporary device, the method of separating the two double pipes 70 and 20 includes arranging the support device 80 in the vicinity of the two double pipes 70 and 20 connected to each other and fixing the sleeve 40 to the lower end of the suspension connection member 83 before releasing the connection of the sleeve 40 to the first double pipe 10 and the second double pipe 20.

[0077] Also in this embodiment, the same effects as those in the first embodiment can be obtained.

[0078] Further, in this embodiment, the sleeve 40 in the standby position overlaps the bellows 31 when viewed in the radial direction and is located outside the bellows 31 in the radial direction. Therefore, since the bellows 31 can be arranged closer to the first outer flange 74, it becomes easier to absorb the positional errors between the first outer flange 74, the second outer flange 24, and the sleeve 40.

[0079] In addition, in the present embodiment, since the sleeve 40 can be moved between the standby position and the connection position while being suspended by the support device 80, the movement of the sleeve 40 can be easily realized. Further, since the sleeve 40 at the standby position can be suspended by the support device 80, it is possible to suppress the load of the sleeve 40 at the standby position from being applied to the first outer tube 73.

[0080] In addition, since the sleeve 40 can be slid by the support device 80, the posture of the sleeve 40 in the standby position with respect to the first outer tube 73 and the first outer flange 74 can be maintained in the same posture as the sleeve 40 in the connection position.

[0081] <Third Embodiment> Next, the double-tube connection structure 1C according to the third embodiment will be described with reference to FIG. 6. FIG. 6 is a cross-sectional view of the double-tube connection structure 1C according to the third embodiment. In FIG. 6, the sleeve 90 in the state of being moved to the standby position is shown by a broken line.

[0082] In the present embodiment, the first outer flange 14 of the first double tube 10 and the first annular portion 92 of the sleeve 90 are not directly connected to each other, but are indirectly connected by the ring plate 100.

[0083] Specifically, the sleeve 90 of the present embodiment is similar to the sleeve 40 of the first embodiment, and includes a cylindrical main body portion 91, a first annular portion 92 that protrudes radially inward from the first end portion (the end portion on the side of the first double tube 10) of the main body portion 41 in the tube axis direction F, and a second annular portion 93 that protrudes radially outward from the second end portion (the end portion on the side of the second double tube 20) of the main body portion 41 in the tube axis direction F. However, in the present embodiment, the inner diameter of the first annular portion 92 is larger than the outer diameter of the first outer flange 14. In the state where the sleeve 90 is in the connection position, the first annular portion 92 faces the first outer flange 14 in the radial direction.

[0084] The ring plate 100 is annular. The outer diameter of the ring plate 100 is smaller than the inner diameter of the main body 91 of the sleeve 90. Also, the inner diameter of the ring plate 100 is equal to or larger than the inner diameters of the first outer tube 13 and the first outer flange 14. Further, the inner diameter of the ring plate 100 is larger than the outer diameter of the first inner flange 12. The ring plate 100 overlaps both the first outer flange 14 and the first annular portion 92 when viewed in the tube axis direction F.

[0085] A plurality of through holes arranged at intervals along the circumferential direction are provided in the first outer flange 14. A bolt 56 is inserted through each through hole. A plurality of through holes arranged at intervals along the circumferential direction are provided in the first annular portion 92. A bolt 57 is inserted through each through hole.

[0086] A plurality of screw holes 101 arranged at intervals along the circumferential direction are provided in the contact surface of the ring plate 100 with the first annular portion 92. Each screw hole 101 is a blind hole that does not penetrate the ring plate 100. The threaded portion of the bolt 57 engages with each screw hole 101. A plurality of screw holes 102 arranged at intervals along the circumferential direction are provided in the contact surface of the ring plate 100 with the first outer flange 14. Each screw hole 102 is a blind hole that does not penetrate the ring plate 100. The threaded portion of the bolt 56 engages with each screw hole 102.

[0087] The space between the sleeve 90 and the first outer flange 14 is sealed by the first sealing material 65 and the second sealing material 66.

[0088] Specifically, the annular first sealing material 65 is sandwiched in the tube axis direction F by the ring plate 100 and the first outer flange 14. The annular first sealing material 65 seals the space between the ring plate 100 and the first outer flange 14. An annular groove for arranging the first sealing material 65 is formed on one or both of the contact surfaces of the ring plate 100 and the first outer flange 14 with each other. It is preferable that the annular groove is present only on the contact surface of the first outer flange 14 among the contact surfaces of the ring plate 100 and the first outer flange 14 with each other.

[0089] Further, the ring plate 100 and the first annular portion 92 sandwich the annular second sealing member 66 in the pipe axis direction F. The annular second sealing member 66 seals between the ring plate 100 and the first annular portion 92. An annular groove for arranging the second sealing member 66 is formed on one or both of the abutting surfaces of the ring plate 100 and the first annular portion 92. It is preferable that the annular groove is only on the abutting surface of the first annular portion 92 among the abutting surfaces of the ring plate 100 and the first annular portion 92.

[0090] Next, a method for separating the first double pipe 10 and the second double pipe 20 using the connection structure 1C of the present embodiment will be described. In a state where the sleeve 90 is at the connection position, it covers the first inner flange 12 and the second inner flange 22. Also, in a state where the sleeve 90 is at the connection position, the sleeve 90 covers the ring plate 100.

[0091] To separate the first double pipe 10 and the second double pipe 20, first, the fastening of the sleeve 90 to the first double pipe 10 and the second double pipe 20 is released. That is, the bolts 57, 54 are removed to release the connection of the sleeve 90 to the first double pipe 10 and the second double pipe 20. Then, the sleeve 90 is moved from the connection position to the standby position.

[0092] The standby position of the sleeve 90 is, as in the first embodiment, between the bellows 31 and the first outer flange 14 in the pipe axis direction F. The sleeve 90 at the connection position is moved away from the second double pipe 20 in the pipe axis direction F to expose the first inner flange 12 and the second inner flange 22. Further, the sleeve 90 is moved away from the second double pipe 20 in the pipe axis direction F to also expose the ring plate 100 accommodated in the sleeve 90. The sleeve 90 in the standby position is supported by the second portion 13b of the first outer pipe 13, as in the first embodiment.

[0093] With the sleeve 90 in the standby position, remove the bolt 51 to disconnect the connection between the first inner tube 11 of the first double tube 10 and the second inner tube 21 of the second double tube 20. In this way, the separation of the first double tube 10 and the second double tube 20, in other words, the separation of the device 2 from the pipe extending from the fluid supply source, is completed.

[0094] Furthermore, remove the bolt 56 to disconnect the connection of the ring plate 100 to the first double tube 10 (more specifically, the first outer flange 14). Then, move the ring plate 100 away from the first outer flange 14 of the first double tube 10 in the pipe axis direction F to remove the ring plate 100 from the first double tube 10. That is, move the ring plate 100 so that the first inner flange 12 passes through the inside of the ring plate 100. Also, move the first sealing material 65 and the second sealing material 66 away from the first double tube 10 and remove them from the first double tube 10. The first sealing material 65 and the second sealing material 66 may be moved integrally with the ring plate 100 or may be moved separately from the ring plate 100. In this way, the first sealing material 65 and the second sealing material 66 can be replaced with new sealing materials.

[0095] Note that since the method of attaching the sealing materials 65, 66 that seal between the first annular portion 92 and the first outer flange 14 is the reverse procedure of the method of removing the sealing materials 65, 66, the description is omitted. Since the method of connecting the first double tube 10 and the second double tube 20 is the reverse procedure of the method of separating the first double tube 10 and the second double tube 20 described above, the description is omitted.

[0096] In this embodiment as well, the same effects as those of the first embodiment can be obtained.

[0097] Also, in this embodiment, when the connection between the first inner tube 11 of the first double tube 10 and the second inner tube 21 of the second double tube 20 is disconnected and one of the first inner tube 11 and the second inner tube 21 is moved away from the other to create a gap between the first inner tube 11 and the second inner tube 21, the sleeve 90 and the ring plate 100 can be completely separated from the first double tube 10 and the second double tube 20 through the gap. For this reason, it becomes easier to perform maintenance on the sleeve 90 and the ring plate 100.

[0098] In addition, in the present embodiment, the first sealing material 65 and the second sealing material 66 can be replaced without passing the first outer flange 14 inside the first sealing material 65 and the second sealing material 66.

[0099] Also, since the screw holes 101 and 102 of the ring plate 100 are blind holes, air does not flow into the sealed space S2 from the screw holes 101 and 102. Therefore, it is easy to ensure the vacuum state of the sealed space S2.

[0100] <Other Embodiments> The present disclosure is not limited to the above-described embodiments, and its configuration can be changed, added, or deleted.

[0101] For example, the device 2 may not be a reservoir. For example, the device 2 may be another device such as an evaporator that evaporates the introduced liquefied hydrogen.

[0102] Also, in the above embodiment, the double pipe connection structures 1A, 1B, and 1C were connection structures for connecting the device 2 and a fluid supply source that supplies a cryogenic fluid to the device 2, but the double pipe connection structure is not limited thereto. For example, it is applicable not only to the connection between a device and a pipe but also to the connection between pipes. That is, the second double pipe may not be a part of the device.

[0103] Also, although the pipe axis direction F coincides with the horizontal direction, the pipe axis direction F may be inclined with respect to the horizontal direction or may coincide with the vertical direction.

[0104] Also, the structures of the first double pipes 10, 70, the second double pipe 20, and the sleeves 40, 90 are not limited to those described in the above embodiments. For example, the first outer flange 14 may not be disposed at the tip of the first outer pipe 13. The main body portions 41, 91 of the sleeves 40, 90 may not be cylindrical. For example, instead of the first outer pipe 13 of the first double pipes 10, 70, the second outer pipe 23 of the second double pipe 20 may be provided with the bellows 31. That is, in the above embodiments, among the first double pipes 10, 70 and the second double pipe 20, the standby positions of the sleeves 40, 90 were on the side of the first double pipes 10, 70 having the bellows 31, but the standby positions of the sleeves 40, 90 may be on the side of the second double pipe 20. The first double pipe 10 may not be provided with the spacer 16.

[0105] The structures of the expansion pipe 30 and the closing member 15 are not limited to those described in the above embodiments.

[0106] In the above first and third embodiments, the sleeves 40, 90 in the standby position were supported by the second portion 13b of the first outer pipe 13, but a support structure for supporting the sleeve 40 may be disposed on the portion 13b of the first outer pipe 13. For example, the support structure may be a plurality of guide bars that guide the sleeve 40 from the connection position to the standby position and support the sleeve 40 in the standby position. In this case, each guide bar extends in the pipe axis direction F, and the plurality of guide bars may be arranged at intervals in the circumferential direction. The guide bar may also serve to prevent the circumferential rotation of the sleeve 40 with respect to the first outer pipe 13. The guide bar may be provided with a stopper that restricts the movement range so that the sleeve 40 does not move beyond the range between the connection position and the standby position.

[0107] Also, the above embodiments and modifications can be combined as appropriate. For example, in the first and third embodiments, the closing member 75 may be employed instead of the closing member 15, or for example, in the second embodiment, the closing member 15 may be employed instead of the closing member 75. In the first and third embodiments, the sleeve 40 may be suspended and supported by the assisting device 80.

[0108] For example, in the above-described embodiment, the sealing materials 61, 62, and 63 may be elastic sheets.

[0109] Although the tube axis direction F, which is the direction in which the center lines of the first double tube and the second double tube extend in the vicinity of the connection portion of the double tube connection structure, has been described as being coincident with the horizontal direction, the tube axis direction F is not limited thereto. For example, the tube axis direction F may be a direction inclined with respect to the horizontal direction or may be a vertical direction.

[0110] The surface of the first outer flange 14 facing the first annular portion 42 may be inclined with respect to the direction perpendicular to the tube axis direction F. That is, the shape of the first outer flange 14 is not a perfect circle but an ellipse, and the surface of the first outer flange 14 on the side opposite to the first annular portion 42 may also be inclined with respect to the direction perpendicular to the tube axis direction F. Since the surfaces of the first outer flange 14 and the first annular portion 42 that sandwich the sealing material 62 are inclined in this way, the size of the sealing material 62 can be increased while suppressing the length of the first outer flange 14 in the direction perpendicular to the tube axis direction F. For this reason, it becomes easier to pass the first outer flange 14 inside the sealing material 62, and the replacement of the sealing material 62 becomes easy.

[0111] [Disclosed Aspect] Each of the following aspects is a disclosure of a preferred embodiment.

[0112] [Aspect 1] A first double tube including a first inner tube, a first inner flange protruding from a tip end portion of the first inner tube, a first outer tube exposing the first inner tube between the first inner flange, and a first outer flange protruding from the first outer tube; A second double tube including a second inner tube, a second inner flange protruding from a tip end portion of the second inner tube and connected to the first inner flange, a second outer tube exposing the second inner tube between the second inner flange, and a second outer flange protruding from the second outer tube; A sleeve that is movable in the axial direction of the pipe between a connection position connected to both the first outer flange and the second outer flange while covering the first inner flange and the second inner flange, and a standby position where the first inner flange and the second inner flange are exposed. The first outer pipe or the second outer pipe includes a bellows that absorbs the positional errors between the first outer flange, the second outer flange, and the sleeve, and the thermal shrinkage of the first inner pipe and the second inner pipe, and has a double pipe connection structure.

[0113] According to the above configuration, the first outer pipe or the second outer pipe has a bellows. That is, since it is not necessary to provide the bellows with respect to the sleeve, the overall length of the sleeve can be shortened, and the workability when connecting or separating two double pipes can be improved.

[0114] [Aspect 2] The first outer pipe includes the bellows. The first double pipe includes a closing member that closes the space between the first outer pipe and the first inner pipe. The closing member and the first outer pipe are connected on the side opposite to the side where the first outer flange is located with respect to the bellows in the axial direction of the pipe. The double pipe connection structure according to Aspect 1, wherein the closing member and the first inner pipe are connected between the bellows and the first inner flange in the axial direction of the pipe.

[0115] According to the above configuration, while preventing the displacement of the bellows from being transmitted to the first inner pipe, the exposed portion of the first inner pipe can be made as small as possible. More specifically, since the closing member and the first outer pipe are connected on the side opposite to the side where the first outer flange is located with respect to the bellows in the axial direction of the pipe, even if the bellows is displaced, the displacement of the bellows can be prevented from being transmitted to the first inner pipe through the closing member. Further, since the closing member and the first inner pipe are connected between the bellows and the first inner flange in the axial direction of the pipe, the exposed portion of the first inner pipe can be made as small as possible.

[0116] [Aspect 3] The first outer tube includes the bellows, The standby position is between the bellows and the first outer flange in the tube axis direction, and is the double-tube connection structure according to Aspect 1 or 2.

[0117] According to the above configuration, it is possible to design the sleeve without considering the interference between the bellows and the sleeve when moving the sleeve from the connection position to the standby position. Therefore, the size of the sleeve can be made smaller compared to the configuration where the standby position of the sleeve coincides with the position of the bellows in the tube axis direction.

[0118] [Aspect 4] The first outer tube includes the bellows, The sleeve in the standby position overlaps the bellows when viewed in the direction perpendicular to the tube axis direction and is outside the bellows, and is the double-tube connection structure according to Aspect 1 or 2.

[0119] According to the above configuration, since the bellows can be arranged at a position close to the first outer flange, it becomes easier to absorb the mutual positional errors of the first outer flange, the second outer flange, and the sleeve.

[0120] [Aspect 5] In the state where the sleeve is at the connection position, the sleeve covers the first outer flange, In the state where the sleeve is at the standby position, the sleeve exposes the first outer flange, and is the double-tube connection structure according to any one of Aspects 1 to 4.

[0121] According to the above configuration, work can be performed on the first outer flange in the state where the sleeve is at the standby position. For example, it becomes easier to perform maintenance on the first outer flange and replace consumables such as sealing materials in the vicinity of the first outer flange.

[0122] [Aspect 6] The first outer tube includes the bellows, The first double pipe according to any one of Aspects 1 to 5 further includes a spacer disposed between the first outer pipe and the first inner pipe and between the bellows and the first inner flange in the pipe axis direction.

[0123] [Aspect 7] The sleeve includes a cylindrical main body portion that encloses the first outer flange when viewed in the pipe axis direction, and an annular portion that protrudes inward from the main body portion and faces the first outer flange in the pipe axis direction when the sleeve is in the connection position. The surfaces of the annular portions facing each other in the pipe axis direction and the surface of the first outer flange are inclined surfaces inclined with respect to the direction perpendicular to the pipe axis direction, respectively. The double pipe connection structure according to any one of Aspects 1 to 6 further includes an annular sealing material that seals between the annular portion and the outer flange, which is sandwiched in the pipe axis direction by the inclined surface of the annular portion and the inclined surface of the first outer flange.

[0124] According to the above configuration, since the surfaces of the annular portion and the first outer flange sandwiching the sealing material are inclined, the size of the sealing material can be increased while suppressing the length of the first outer flange in the direction perpendicular to the pipe axis direction. Therefore, it becomes easier to pass the first outer flange inside the sealing material, and the replacement of the sealing material becomes easy.

[0125] [Aspect 8] The sleeve includes a cylindrical main body portion that encloses the first outer flange when viewed in the pipe axis direction, and an annular portion that protrudes inward from the main body portion and faces the first outer flange in the direction perpendicular to the pipe axis direction when the sleeve is in the connection position. The double pipe connection structure includes an annular ring plate that overlaps both the annular portion and the first outer flange when viewed in the pipe axis direction and indirectly connects the annular portion and the first outer flange when the sleeve is in the connection position. An annular first sealing material sandwiched in the pipe axis direction by the ring plate and the annular portion, An annular second sealing material sandwiched in the pipe axis direction by the ring plate and the first outer flange, and further comprising the double pipe connection structure according to any one of Aspects 1 to 7.

[0126] According to the above configuration, the first sealing material and the second sealing material can be replaced without passing the first outer flange inside the first sealing material and the second sealing material.

[0127] [Aspect 9] A first double pipe including a first inner pipe, a first inner flange protruding from the tip of the first inner pipe, a first outer pipe exposing the first inner pipe between the first inner flange, and a first outer flange protruding from the first outer pipe, A second double pipe including a second inner pipe, a second inner flange protruding from the tip of the second inner pipe and connected to the first inner flange, a second outer pipe exposing the second inner pipe between the second inner flange, and a second outer flange protruding from the second outer pipe, A sleeve movable in the pipe axis direction between the first inner flange and the second inner flange between a connection position connected to both the first outer flange and the second outer flange in a state covering the first inner flange and the second inner flange, and a standby position exposing the first inner flange and the second inner flange, the sleeve including a cylindrical main body portion enclosing the first outer flange when viewed in the pipe axis direction, and an annular portion protruding inward from the main body portion and facing the first outer flange in a direction perpendicular to the pipe axis direction when the sleeve is in the connection position, An annular ring plate overlapping both the annular portion and the first outer flange when viewed in the pipe axis direction in a state where the sleeve is in the connection position, and indirectly connecting the annular portion and the first outer flange, An annular first sealing material sandwiched in the pipe axis direction by the ring plate and the annular portion, A double pipe connection structure comprising an annular second sealing material sandwiched in the pipe axis direction by the ring plate and the first outer flange.

[0128] According to the above configuration, the first sealing material and the second sealing material can be replaced without passing the first outer flange inside the first sealing material and the second sealing material.

[0129] Also, when the connection between the first inner pipe of the first double pipe and the second inner pipe of the second double pipe is released, and one of the first inner pipe and the second inner pipe is moved away from the other to create a gap between the first inner pipe and the second inner pipe, the sleeve and the ring plate can be completely separated from the first double pipe and the second double pipe through the gap. Therefore, it becomes easier to perform maintenance on the sleeve and the ring plate.

[0130] [Aspect 10] The double pipe connection structure according to any one of Aspects 1 to 9, and an assisting device for assisting the movement of the sleeve between the standby position and the connection position. The assisting device includes a rail extending in a direction parallel to the pipe axis direction above the double pipe connection structure, a slider supported by the rail and slidable in the pipe axis direction, and a suspension connection member connecting the slider and the sleeve, and is a connection system.

[0131] According to the above configuration, since the sleeve can be moved between the standby position and the connection position while the sleeve is suspended by the assisting device, the movement of the sleeve can be easily realized. Also, since the sleeve in the standby position can be suspended by the assisting device, the load on the sleeve in the standby position applied to the first outer pipe can be suppressed.

[0132] [Aspect 11] A first double tube including a first inner tube, a first inner flange protruding from a tip end portion of the first inner tube, a first outer tube exposing the first inner tube between the first inner flange, and a first outer flange protruding from the first outer tube. A second double tube including a second inner tube, a second inner flange protruding from a tip end portion of the second inner tube and connected to the first inner flange, a second outer tube exposing the second inner tube between the second inner flange, and a second outer flange protruding from the second outer tube. A sleeve movable in an axial direction of the tube between a connection position connected to both the first outer flange and the second outer flange in a state of covering the first inner flange and the second inner flange, and a standby position exposing the first inner flange and the second inner flange. In a double tube connection structure including an annular sealing material that abuts against the first outer flange and seals between the sleeve and the first outer flange, a method for replacing the sealing material of the double tube connection structure for replacing the sealing material, Releasing the fastening of the sleeve to the first double tube and the second double tube. Moving the sleeve at the connection position away from the second double tube in the axial direction of the tube to expose the first inner flange and the second inner flange. Moving the sleeve further away from the second double tube in the axial direction of the tube to expose the first outer flange. A method for replacing the sealing material of a double tube connection structure, in which the sealing material is removed from the first outer flange and replaced with a new sealing material.

[0133] According to the method, it becomes easier to replace the sealing material that abuts against the first outer flange in a state where the first outer flange is exposed.

Description of Reference Numerals

[0134] 1A: Double tube connection structure 1B: Double tube connection structure 1C: Double tube connection structure 10: First double tube 11: First inner tube 12: First inner flange 13: First outer tube 14: First outer flange 14a: First outer flange 15: Blocking member 20: Second double tube 21: Second inner tube 22: Second inner flange 23: Second outer tube 24: Second outer flange 30: Telescopic tube 31: Bellows 32: First cover 33: Second cover 40: Sleeve 41: Body part 42: First annular part 42a: First outer flange 43: Second annular part 51: Bolt 52: Nut 53: Bolt 54: Bolt 55: Nut 56: Bolt 57: Bolt 61: Sealing material 62: Sealing material 62a: Sealing material 63: Sealing material 65: Sealing material 65: First sealing material 66: Second sealing material 70: First double tube 71: First inner tube 72: First inner flange 73: First outer tube 74: First outer flange 75: Blocking member 76: Slide rail 80: Support device 81: Rail 82: Slider 83: Hanging connection member 90: Sleeve 91: Body part 92: First annular part 93: Second annular part 100: Ring plate

Claims

1. A first double tube including a first inner tube, a first inner flange protruding from a tip of the first inner tube, a first outer tube exposing the first inner tube between the first inner flange, and a first outer flange protruding from the first outer tube; A second double tube including a second inner tube, a second inner flange protruding from a tip of the second inner tube and connected to the first inner flange, a second outer tube exposing the second inner tube between the second inner flange, and a second outer flange protruding from the second outer tube; A sleeve movable in the axial direction of the tube between a connection position connected to both the first outer flange and the second outer flange in a state covering the first inner flange and the second inner flange, and a standby position exposing the first inner flange and the second inner flange; The first outer tube or the second outer tube includes a bellows that absorbs positional errors between the first outer flange, the second outer flange, and the sleeve, and thermal shrinkage of the first inner tube and the second inner tube, a double tube connection structure.

2. The first outer tube includes the bellows; The first double tube includes a closing member that closes a space between the first outer tube and the first inner tube; The closing member and the first outer tube are connected on the side opposite to the side where the first outer flange is located with respect to the bellows in the axial direction of the tube; The closing member and the first inner tube are connected between the bellows and the first inner flange in the axial direction of the tube, the double tube connection structure according to claim 1.

3. The first outer tube includes the bellows; The standby position is between the bellows and the first outer flange in the axial direction of the tube, the double tube connection structure according to claim 1 or 2.

4. The first outer tube includes the bellows; The sleeve in the standby position overlaps the bellows when viewed in a direction perpendicular to the axial direction of the tube and is outside the bellows, the double tube connection structure according to claim 1 or 2.

5. In a state where the sleeve is in the connection position, the sleeve covers the first outer flange; In a state where the sleeve is in the standby position, the sleeve exposes the first outer flange, the double tube connection structure according to claim 1 or 2.

6. The first outer tube includes the bellows; The first double pipe according to claim 1 or 2, further comprising a spacer disposed between the first outer pipe and the first inner pipe and between the bellows and the first inner flange in the pipe axis direction.

7. The sleeve has a cylindrical main body portion that encloses the first outer flange when viewed in the pipe axis direction, and an annular portion that protrudes inward from the main body portion and faces the first outer flange in the pipe axis direction when the sleeve is in the connection position, wherein the surfaces of the annular portions facing each other in the pipe axis direction and the surface of the first outer flange are inclined surfaces inclined with respect to the direction perpendicular to the pipe axis direction, The double pipe connection structure according to claim 1 or 2, further comprising an annular sealing material that seals between the annular portion and the outer flange, which is sandwiched in the pipe axis direction by the inclined surface of the annular portion and the inclined surface of the first outer flange.

8. The sleeve has a cylindrical main body portion that encloses the first outer flange when viewed in the pipe axis direction, and an annular portion that protrudes inward from the main body portion and faces the first outer flange in a direction perpendicular to the pipe axis direction when the sleeve is in the connection position, The double pipe connection structure includes, when the sleeve is in the connection position, an annular ring plate that overlaps both the annular portion and the first outer flange when viewed in the pipe axis direction and indirectly connects the annular portion and the first outer flange, an annular first sealing material sandwiched in the pipe axis direction by the ring plate and the annular portion, and an annular second sealing material sandwiched in the pipe axis direction by the ring plate and the first outer flange. The double pipe connection structure according to claim 1 or 2.

9. A first double pipe including a first inner pipe, a first inner flange protruding from the tip of the first inner pipe, a first outer pipe exposing the first inner pipe between the first inner flange, and a first outer flange protruding from the first outer pipe, a second double pipe including a second inner pipe, a second inner flange protruding from the tip of the second inner pipe and connected to the first inner flange, a second outer pipe exposing the second inner pipe between the second inner flange, and a second outer flange protruding from the second outer pipe A sleeve that is movable in the axial direction of the first inner flange and the second inner flange between a connection position connected to both the first outer flange and the second outer flange in a state of covering the first inner flange and the second inner flange, and a standby position for exposing the first inner flange and the second inner flange. The sleeve includes a cylindrical main body portion that encloses the first outer flange when viewed in the axial direction, and an annular portion that protrudes inward from the main body portion and faces the first outer flange in a direction perpendicular to the axial direction of the sleeve when the sleeve is in the connection position. An annular ring plate that overlaps both the annular portion and the first outer flange when viewed in the axial direction and indirectly connects the annular portion and the first outer flange when the sleeve is in the connection position. An annular first sealing material sandwiched in the axial direction between the ring plate and the annular portion. An annular second sealing material sandwiched in the axial direction between the ring plate and the first outer flange. A double pipe connection structure comprising:

10. The double pipe connection structure according to claim 1 or 9, and An assisting device that assists the movement of the sleeve between the standby position and the connection position. The assisting device includes: A rail extending in a direction parallel to the axial direction above the double pipe connection structure, A slider supported by the rail and slidable in the axial direction, and A suspension connection member that connects the slider and the sleeve. A connection system comprising:

11. A first double pipe including a first inner pipe, a first inner flange protruding from the tip of the first inner pipe, a first outer pipe that exposes the first inner pipe between the first inner flange, and a first outer flange protruding from the first outer pipe. A second double pipe including a second inner pipe, a second inner flange protruding from the tip of the second inner pipe and connected to the first inner flange, a second outer pipe that exposes the second inner pipe between the second inner flange, and a second outer flange protruding from the second outer pipe. A sleeve that is movable in the axial direction of the first inner flange and the second inner flange between a connection position connected to both the first outer flange and the second outer flange in a state of covering the first inner flange and the second inner flange, and a standby position for exposing the first inner flange and the second inner flange. In a double pipe connection structure including an annular sealing material that abuts against the first outer flange and seals between the sleeve and the first outer flange, a method for replacing the sealing material of the double pipe connection structure for replacing the sealing material, Release the fastening of the sleeve to the first double pipe and the second double pipe, Move the sleeve at the connection position away from the second double pipe in the pipe axis direction to expose the first inner flange and the second inner flange, Move the sleeve further away from the second double pipe in the pipe axis direction to expose the first outer flange, A method for replacing the sealing material of a double pipe connection structure, which removes the sealing material from the first outer flange and replaces it with a new sealing material.

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