Double pipe connection structure, connection system, and method for replacing seal of double pipe connection structure

Abstract

A double pipe connection structure comprises: a first double pipe including a first inner pipe, a first inner-side flange, a first outer pipe that exposes the first inner pipe between the first inner-side flange and the first outer pipe, and a first outer-side flange; a second double pipe including a second inner pipe, a second inner-side flange, a second outer pipe that exposes the second inner pipe between the second inner-side flange and the second outer pipe, and a second outer-side flange; and a sleeve that can move in the pipe-axis direction of the first inner-side flange and the second inner-side flange between a connection position at which the sleeve is connected to both the first outer-side flange and the second outer-side flange in a state of covering the first inner-side flange and the second inner-side flange, and a standby position at which the sleeve exposes the first inner-side flange and the second inner-side flange. The first outer pipe or the second outer pipe includes a bellows that absorbs error in the positioning between the first outer-side flange, the second outer-side flange, and the sleeve, and thermal contraction of the first inner pipe and the second inner pipe.

Description

Double pipe connection structure, connection system, and method for replacing seal material in double pipe connection structure

[0001] The present disclosure relates to a double pipe connection structure, a connection system, and a method for replacing a seal material in a double pipe connection structure.

[0002] Patent Document 1 discloses a connection structure that enables double-walled pipes to be connected to each other. The connection structure in Patent Document 1 includes a first double-walled pipe and a second double-walled pipe. The first double-walled pipe and the second double-walled pipe each include an inner pipe and an outer pipe that exposes the vicinity of the tip of the inner pipe. A sleeve is attached to the second double-walled pipe. The sleeve slides between a standby position that exposes the tip of the inner pipe of the second double-walled pipe and a connection position where it is fastened to the outer pipe of the first double-walled pipe and the outer pipe of the second double-walled pipe. The sleeve also has a bellows that absorbs axial misalignment between the outer pipe of the first double-walled pipe and the outer pipe of the second double-walled pipe. The sleeve slides between the standby position and the connection position during the connection and disconnection operations of the first double-walled pipe and the second double-walled pipe.

[0003] Japanese Patent Application Laid-Open No. 2017-202783

[0004] A connection structure that improves workability is desired for the sleeve, which needs to be moved when connecting or disconnecting the first double pipe and the second double pipe.

[0005] Therefore, an object of the present disclosure is to provide a double pipe connection structure, a connection system, and a method for replacing a sealant in a double pipe connection structure that can improve workability when connecting or disconnecting two double pipes.

[0006] In order to solve the above problems, a double pipe connection structure according to one aspect of the present disclosure includes a first double pipe including a first inner pipe, a first inner flange protruding from a tip end portion of the first inner pipe, a first outer pipe exposing the first inner pipe between the first inner flange and 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 a tip end portion 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 the second inner flange, and a second outer flange protruding from the second outer pipe; and a sleeve that is movable in the axial direction of the first inner flange and the second inner flange between a connection position where it is 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 it exposes the first inner flange and the second inner flange, and the first outer tube or the second outer tube includes a bellows that absorbs relative position errors between the first outer flange, the second outer flange, and the sleeve, as well as thermal contraction of the first inner tube and the second inner tube.

[0007] A double pipe connection structure according to another aspect of the present disclosure includes a first double pipe including a first inner pipe, a first inner flange protruding from a tip end of the first inner pipe, a first outer pipe exposing the first inner pipe between the first inner flange and 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 a tip end 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 the second inner flange, and a second outer flange protruding from the second outer pipe; a connection position where the first double pipe is 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 double pipe is exposed to the second inner flange and the second inner flange. the sleeve being movable in the axial direction of the pipe between the first inner flange and the second inner flange, the sleeve including: a cylindrical main body portion that contains the first outer flange as viewed in the axial direction of the pipe; 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 pipe when the sleeve is in the connected position; an annular ring plate that overlaps both the annular portion and the first outer flange as viewed in the axial direction of the pipe when the sleeve is in the connected position, and indirectly connects the annular portion and the first outer flange; an annular first sealing material that is sandwiched between the ring plate and the annular portion in the axial direction of the pipe; and an annular second sealing material that is sandwiched between the ring plate and the first outer flange in the axial direction of the pipe.

[0008] A connection system according to one aspect of the present disclosure comprises the double pipe connection structure and an assistance device that assists movement of the sleeve between the standby position and the connection position, the assistance device including a rail extending in a direction parallel to the pipe axis direction above the double pipe connection structure, a slider supported on the rail and slidable in the pipe axis direction, and a hanging connection member that connects the slider and the sleeve.

[0009] A method for replacing a sealant in a double pipe connection structure according to one aspect of the present disclosure includes a first double pipe including a first inner pipe, a first inner flange protruding from a tip end of the first inner pipe, a first outer pipe exposing the first inner pipe between the first inner flange and 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 a tip end 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 the second inner flange, and a second outer flange protruding from the second outer pipe; 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 connection position exposing the first inner flange and the second inner flange; A method for replacing a sealing material in a double pipe connection structure comprising a sleeve that is movable in the pipe axial direction between the first inner flange and the second inner flange and a standby position, and an annular sealing material that abuts the first outer flange and seals between the sleeve and the first outer flange, the method comprising: releasing the fastening of the sleeve to the first double pipe and the second double pipe; moving the sleeve in the connection position away from the second double pipe in the pipe axial direction to expose the first inner flange and the second inner flange; moving the sleeve further away from the second double pipe in the pipe axial direction to expose the first outer flange; removing the sealing material from the first outer flange; and replacing it with a new sealing material.

[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 sealant in a double pipe connection structure that can improve workability when connecting or disconnecting two double pipes.

[0011] Fig. 3 is a cross-sectional view of a double pipe connection structure according to a first embodiment. Fig. 4 is a cross-sectional view of the double pipe connection structure shown in Fig. 1 with a sleeve moved to a standby position. Fig. 5 is an enlarged cross-sectional view of the vicinity of a tip portion of a first outer pipe. Fig. 6 is a cross-sectional view taken along the arrows IV-IV in Fig. 3. Fig. 7 is a cross-sectional view of a double pipe connection structure according to a second embodiment. Fig. 8 is a cross-sectional view of a double pipe connection structure according to a third embodiment.

[0012] Hereinafter, an embodiment 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 to a fluid supply source that supplies a cryogenic fluid to the device 2. The cryogenic fluid is a low-temperature liquefied gas or vaporized gas. In this example, the cryogenic fluid is liquefied hydrogen.

[0014] (Configuration of 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 a tip end of a pipe extending from a 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, i.e., the direction along which the center lines of the first double pipe 10 and the second double pipe 20 extend near the connection point, will be referred to as the pipe axis direction F. The pipe axis direction F can also be referred to as the extension 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. Furthermore, the direction perpendicular to the center lines of the first double pipe 10 and the second double pipe 20 will be 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 cryogenic fluid to flow through it. The first inner flange 12 is disposed at the tip of the first inner pipe 11. The first inner flange 12 has a plurality of through holes arranged at intervals along the circumferential direction. A bolt 51 is inserted into each through hole.

[0018] The tip of the first outer pipe 13 is located at a position away from the first inner flange 12. In other words, the first inner pipe 11 is exposed between the first outer pipe 13 and the first inner flange 12. This is to ensure the space necessary for attaching and fastening the bolts 51 and nuts 52 described below.

[0019] The first outer flange 14 is disposed at the tip end of the first outer pipe 13. A plurality of screw holes are arranged at intervals along the circumferential direction on the abutment surface of the first outer flange 14 that abuts against a first annular portion 42 (described later). Each screw hole is a blind hole that does not pass through the first outer flange 14. The threads of the bolts 53 engage with each screw hole.

[0020] The first outer pipe 13 has a telescopic tube 30. In other words, a portion of the first outer pipe 13 is constituted by the telescopic tube 30. The telescopic tube 30 has a bellows 31 and a first cover 32 and a second cover 33 that surround and protect the bellows 31. The bellows 31 allows a portion 13b (hereinafter referred to as the second portion 13b) of the first outer pipe 13 between the bellows 31 and the first outer flange 14 to be displaced relative to a portion 13a (hereinafter referred to as the first portion 13a) of the first outer pipe 13 that is located on the opposite side of the bellows 31 from the first outer flange 14. Therefore, the bellows 31 allows the first outer flange 14 to be displaced to a predetermined position relative to the second outer flange 24, which will be described later. More specifically, the bellows 31 absorbs any positional error between the first outer flange 14, the second outer flange 24, and the sleeve 40 so that the sleeve 40 can be fastened to the first outer flange 14 and a second outer flange 24 (described later) (in other words, so that the positions of the through holes or screw holes align with each other). The bellows 31 also absorbs thermal contraction of the first inner tube 11 and the second inner tube 21.

[0021] The first cover 32 and the second cover 33 are movable relative 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 pipe 10 includes a blocking member 15 that blocks the space S1 between the first inner pipe 11 and the first outer pipe 13. The space S1 blocked by the blocking member 15 is evacuated to a vacuum by, for example, a pump (not shown).

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

[0024] In this embodiment, the blocking member 15 includes two ring plates 15a, 15b and a tube 15c connecting the two ring plates 15a, 15b. The ring plate 15a protrudes radially inward from the first outer tube 13 on the side of the bellows 31 opposite the side where the first outer flange 14 is located 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 tube 15c extends in the tube axis direction F between the first inner tube 11 and the first outer tube 13. The tube 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 that stores the cryogenic fluid in a low temperature state. Specifically, the device 2 includes a second double pipe 20, an inner tank 3 that stores the cryogenic fluid introduced through the second double pipe 20, and an outer tank 4 that covers the inner tank 3.

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

[0027] The base end of the second inner pipe 21 (the end opposite the second inner flange 22) is connected to the receiving port 3a of the inner tank 3. The base end of the second outer pipe 23 (the end opposite 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 pipe 21 and the second outer pipe 23. Therefore, the space between the inner tank 3 and the outer tank 4 and the space between the second inner pipe 21 and the second outer pipe 23 are simultaneously evacuated by a pump (not shown).

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

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

[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 inner pipe 21 is exposed between the second outer pipe 23 and the second inner flange 22. This is to ensure the space necessary for attaching and fastening the bolts 51 and nuts 52 described below.

[0031] The second outer flange 24 is disposed at the tip end of the second outer pipe 23. A plurality of through holes are arranged at intervals along the circumferential direction in the second outer flange 24. A bolt 54 is inserted into 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, with a sealant 61 interposed therebetween. As described above, the first inner flange 12 and the second inner flange 22, as well as the first inner pipe 11 and the second inner pipe 21 near these flanges 12, 22, are exposed. 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 pipe 10 and the second outer flange 24 of the second double pipe 20. As a result, the sleeve 40 forms a sealed space S2 around the first double pipe 10 and the second double pipe 20 between the first outer flange 14 and the second outer flange 24.

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

[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 protrudes radially inward from a first end portion (the end portion on the first double pipe 10 side) of the main body portion 41 in the pipe axis direction F. The second annular portion 43 protrudes radially outward from a second end portion (the end portion on the second double pipe 20 side) of the main body portion 41 in the pipe axis direction F. In other words, the first annular portion 42 is smaller than the second annular portion 43.

[0036] When the sleeve 40 is in the connected position, the cylindrical main body 41 covers the first inner flange 12 and the second inner flange 22. That is, when the sleeve 40 is in the connected position, the cylindrical main body 41 is positioned so as to overlap the first inner flange 12 and the second inner flange 22 when viewed in the radial direction.

[0037] The main body portion 41 contains the first outer flange 14 when viewed in the pipe 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. When the sleeve 40 is in the connected position, the first outer flange 14 is housed within the sleeve 40. The inner diameter of the main body portion 41 and the inner diameter of the second outer pipe 23 are approximately 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 pipe axis direction F. The first annular portion 42 has a plurality of through holes arranged at intervals in the circumferential direction. A bolt 53 is inserted into each of the through holes. The second annular portion 43 faces the second outer flange 24 in the pipe axis direction F. The second annular portion 43 has a plurality of through holes arranged at intervals in the circumferential direction. A bolt 54 is inserted into each of the through holes.

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

[0040] An annular sealing material 62 is sandwiched between the first annular portion 42 and the first outer flange 14 in the pipe 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 opposite the second outer flange 24, with the sealing material 62 sandwiched between them. An annular groove 64 (see FIG. 3 ) for locating 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. Note that it is preferable that the annular groove 64 be present 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] An annular sealing material 63 is sandwiched between the second annular portion 43 and the second outer flange 24 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 sandwiched between them. An annular groove for locating 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 be present 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.

[0042] The types of the seal materials 61, 62, and 63 may be different from one another. For example, the seal material 61 is for use at extremely low temperatures, but the seal materials 62 and 63 do not have to be for use at extremely low temperatures. Furthermore, as will be described later, the seal material 62 has elasticity because it needs to be moved in the tube axis direction F so as to overcome the first outer flange 14 when replaced. For example, the seal material 62 may be a rubber O-ring. On the other hand, the seal materials 61 and 63 do not have to have elasticity. For example, the seal 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 sealant 62 that seals the space between them. The bolts 53 engage with threaded holes in 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 sealant 63 that seals the space 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 this embodiment will be described with appropriate reference to Figures 1 and 2. As shown in Figure 1, when the sleeve 40 is in the connection position, it covers the first inner flange 12 and the second inner flange 22. Furthermore, when the sleeve 40 is in the connection position, it covers the first outer flange 14.

[0045] To separate the first double pipe 10 and the second double pipe 20, first, the sleeve 40 is released from the first double pipe 10 and the second double pipe 20. That is, the bolts 53 and 54 are removed to release the connection of the sleeve 40 to the first double pipe 10 and the second double pipe 20. Thereafter, the sleeve 40 is moved from the connection position to the standby position.

[0046] 2 is a cross-sectional view of the double pipe connection structure 1A with the sleeve 40 moved to the standby position. In this embodiment, the standby position is between the bellows 31 and the first outer flange 14 in the pipe axis direction F. The sleeve 40, which is in 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. Furthermore, by moving the sleeve 40 away from the second double pipe 20 in the pipe axis direction F, the first outer flange 14 housed within the sleeve 40 is also exposed (see the two-dot chain line in FIG. 2 ).

[0047] When in the standby position, the sleeve 40 is supported by the second portion 13b of the first outer pipe 13 between the bellows 31 and the first outer flange 14. For example, as shown in FIG. 2 , the sleeve 40 is supported by the first outer pipe 13 with a portion of the inner circumferential surface of the main body 41 of the sleeve 40 (near the first annular portion 42) abutting against the outer circumferential surface of the first outer pipe 13.

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

[0049] The method for connecting the first double pipe 10 and the second double pipe 20 is the reverse of the method for separating the first double pipe 10 and the second double pipe 20, and therefore will not be described here. After the bolts 53, 54 are tightened 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 create a vacuum.

[0050] When the sleeve 40 is released from the first double pipe 10 and the second double pipe 20, the gravity of the second portion 13b of the first outer pipe 13 and the first outer flange 14 may deform the bellows 31, causing the second portion 13b of the first outer pipe 13 to sag downward. When the second portion 13b sags downward, it is necessary to lift the sagging second portion 13b in order to refasten the sleeve 40 to the first double pipe 10 and the second double pipe 20. In this embodiment, the first double pipe 10 has a spacer 16 that prevents the second portion 13b of the first outer pipe 13 from sagging when the sleeve 40 is released from the first double pipe 10 and the second double pipe 20, so as to reduce the burden of lifting the second portion 13b during refastening.

[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 thermal insulation properties. In this embodiment, the spacer 16 is disposed between the tube 15c of the closing member 15 and the first outer tube 13 in the radial direction. The spacer 16 is fixed to the tube 15c, and when the second portion 13b of the first outer tube 13 sags due to deformation of the bellows 31, the spacer 16 and the second portion 13b come into contact with each other. 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. Alternatively, the spacer 16 may be fixed to the second portion 13b of the first outer tube 13 instead of the tube 15c, or to a portion of the first inner tube 11 between the ring plate 15b and the first inner flange 12. In this way, even when the sleeve 40 is released from the first double pipe 10 and the second double pipe 20, the spacer 16 keeps the degree of sagging of the second portion 13b of the first outer pipe 13 within a certain range, thereby reducing the burden of lifting the second portion 13b when refastening the sleeve 40 to the first double pipe 10 and the second double pipe 20.

[0052] (Replacing the sealing material) In this embodiment, when the sleeve 40 is in the standby position, the first outer flange 14 is exposed. The reason for exposing the first outer flange 14 is to replace the sealing material 62, which is a consumable item.

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

[0054] An annular groove 64 for disposing the sealant 62 is formed on the contact surface of the first outer flange 14 that contacts the first annular portion 42. When removing the sealant 62, the sealant 62 is moved so that the first outer flange 14 passes inside the sealant 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 pipe 13. Furthermore, the sealing material 62 is disposed on the abutting surface of the first outer flange 14, near the outer peripheral edge of the first outer flange 14. To remove the sealing material 62 from the first double pipe 10, the sealing material 62 is first removed from the groove 64, and a portion of the sealing material 62 is brought close to or in contact with the outer peripheral surface of the outer pipe 13. In this state, as shown by the two-dot chain line in FIG. 3 , the portion of the sealing material 62 opposite the portion that is close to or in contact with the outer pipe 13 is moved over the first outer flange 14. Thereafter, the portion of the sealing material 62 that is close to or in contact with the outer pipe 13 is moved over the first outer flange 14. In this manner, the sealing material 62 can be removed from the first double pipe 10 and replaced with a new sealing material.

[0056] The method for attaching the seal material 62 to the first double pipe 10 is the reverse of the method for removing the seal material 62 from the first double pipe 10, and therefore a description thereof will be omitted.

[0057] (Operation and Effect) As described above, according to the double pipe connection structure 1A of this embodiment, the first outer pipe 13, rather than the sleeve 40, has the expansion pipe 30 including the bellows 31. In other words, since there is no need to provide the bellows 31 to the sleeve 40, the overall length of the sleeve 40 can be shortened, and the workability when connecting or disconnecting the two double pipes 10, 20 can be improved.

[0058] Furthermore, in this embodiment, the closing member 15 and the first outer pipe 13 are connected to the bellows 31 on the side opposite to the side where the first outer flange 14 is located in the pipe axis direction F, so even if the bellows 31 is displaced, the displacement of the bellows 31 can be prevented from being transmitted to the first inner pipe 11 via the closing member 15. Furthermore, because the closing member 15 and the first inner pipe 11 are connected between the bellows 31 and the first inner flange 12 in the pipe axis direction F, the exposed portion of the first inner pipe 11 can be made as small as possible. In other words, the exposed portion of the first inner pipe 11 can be made as small as possible while preventing the displacement of the bellows 31 from being transmitted to the first inner pipe 11.

[0059] In addition, the total length from the connection point of the blocking member 15 with the first inner pipe 11 to the connection point with the first outer pipe 13 can be increased, thereby preventing the cold energy of the low-temperature fluid flowing through the first inner pipe 11 from being transferred to the first outer pipe 13 via the blocking member 15.

[0060] Furthermore, in this embodiment, the standby position of the sleeve 40 is between the bellows 31 and the first outer flange 14 in the pipe axis direction F. This makes it possible to design the sleeve 40 without considering interference between the expansion tube 30 and the sleeve 40 when the sleeve 40 is moved from the connected position to the standby position. This allows the size of the sleeve 40 to be smaller than in a configuration in which the bellows and sleeve are aligned perpendicular to the pipe axis direction when the sleeve is in the standby position.

[0061] Furthermore, in this embodiment, when the sleeve 40 is in the connected 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. Therefore, work can be performed on the first outer flange 14 while the sleeve 40 is in the standby position. For example, this makes it easier to perform maintenance on the first outer flange 14 and replace consumables such as the sealant 62 near the first outer flange 14.

[0062] Furthermore, the first annular portion 42 and the first outer flange 14 are fastened together by bolts 53 that pass through the first annular portion 42 and engage with threaded holes in the first outer flange 14. Because air does not flow into the sealed space S2 through the blind threaded holes, it is easy to ensure a vacuum state in the sealed space S2.

[0063] Second Embodiment Next, a double pipe connection structure 1B according to a second embodiment will be described with reference to Fig. 5. Regarding the second embodiment and a third embodiment described later, differences from the first embodiment will be mainly described, and descriptions overlapping with the first embodiment will be omitted.

[0064] Fig. 5 is a cross-sectional view of a double pipe connection structure 1B according to the second embodiment. In Fig. 5, the sleeve 40 is shown by a dashed line when moved to the standby position. In this embodiment, the structure of the first double pipe 70 is different from the structure of the first double pipe 10 of the first embodiment.

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

[0066] The tip end of the first outer pipe 73 is located at a position away from the first inner flange 72. In other words, the first outer pipe 73 exposes the first inner pipe 71 between itself 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 closer to the first outer flange 74 (i.e., closer to the tip) than 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 expandable 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 pipe 70 includes a blocking member 75 that blocks the space S1 between the first inner pipe 71 and the first outer pipe 73. The blocking member 75 radially connects the first inner pipe 71 and the first outer pipe 73. The blocking member 75 is functionally the same as the blocking member 15 of the first embodiment, but is structurally different.

[0069] Specifically, the closing member 75 includes a cylindrical portion 75a and a ring plate 75b connecting the cylindrical portion 75a and the first inner tube 71. The cylindrical portion 75a extends toward the second double pipe 20 from the tip end of the small diameter portion 73a, i.e., from the connection point between the small diameter portion 73a and 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 by a single pipe member. The ring plate 75b is located between the first inner flange 72 and the bellows 31 in the pipe axis direction F. In this embodiment, the ring plate 75b is located between the first outer flange 74 and the bellows 31 in the pipe 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 outward of 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 extending in the tube axis direction F on a cylindrical peripheral surface and spaced apart in the circumferential direction. If the slide rail 76 includes a plurality of bars, the first annular portion 42 of the sleeve 40 may have a plurality of grooves into which the bars respectively fit. If the slide rail 76 includes a plurality of grooves, the first annular portion 42 of the sleeve 40 may have a plurality of protrusions which respectively fit into the plurality of grooves. The slide rail 76 may also serve to prevent circumferential rotation of the sleeve 40 relative to the first outer tube 73. The slide rail 76 may include a stopper that limits the movement range of the sleeve 40 so that it does not move beyond the range between the connection position and the standby position.

[0072] 5, the slide rail 76 supports the sleeve 40 when it is positioned at the standby position. That is, the bellows 31 is positioned radially inward of the slide rail 76, and the sleeve 40 when it is positioned at the standby position is positioned radially outward of the slide rail 76. In this manner, in this embodiment, the sleeve 40 in the standby position overlaps with the bellows 31 when viewed in the radial direction and is positioned radially outward of the bellows 31.

[0073] In this embodiment, an assist device 80 is disposed near the double pipe connection structure 1B. The assist device 80 assists the movement of the sleeve 40 between the standby position and the connection position. The double pipe connection structure 1B and the assist device 80 constitute a connection system that connects or disconnects two double pipes 70, 20 to each other.

[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 hanging connection member 83 connecting the slider 82 to the sleeve 40. The rail 81 and the slider 82 are located above the double-pipe connection structure 1B. The hanging connection member 83 extends downward from the slider 82. A lower end of the hanging connection member 83 is connected to, for example, the main body 41 of the sleeve 40. The hanging connection member 83 is, for example, a chain or a rope.

[0075] The method for connecting or separating two double pipes 70, 20 in this embodiment is basically the same as in the first embodiment, but in this embodiment, when moving the sleeve 40 between the standby position and the connection position, the sleeve 40 is moved while being suspended and supported by the support device 80.

[0076] The support device 80 does not have to be a device permanently installed near the double pipe connection structure 1B, and may be, for example, a temporary device that is installed only when performing work to connect or disconnect the two double pipes 70, 20. When the support device 80 is a temporary device, a method for separating the two double pipes 70, 20 includes placing the support device 80 near the two connected double pipes 70, 20 and fixing the sleeve 40 to the lower end of the hanging connection member 83 before releasing the connection of the sleeve 40 to the first double pipe 10 and the second double pipe 20.

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

[0078] Furthermore, in this embodiment, the sleeve 40 in the standby position overlaps with the bellows 31 when viewed in the radial direction, and is located radially outward of the bellows 31. Therefore, the bellows 31 can be disposed in a position close to the first outer flange 74, which makes it easier to absorb positional errors between the first outer flange 74, the second outer flange 24, and the sleeve 40.

[0079] Furthermore, in this embodiment, the sleeve 40 can be moved between the standby position and the connection position while being suspended by the support device 80, which facilitates movement of the sleeve 40. Furthermore, since the sleeve 40 in the standby position can be suspended by the support device 80, it is possible to prevent the weight of the sleeve 40 in the standby position from being applied to the first outer tube 73.

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

[0081] Third Embodiment Next, a double pipe connection structure 1C according to a third embodiment will be described with reference to Fig. 6. Fig. 6 is a cross-sectional view of the double pipe connection structure 1C according to the third embodiment. In Fig. 6, the sleeve 90 is shown by a dashed line in a state where it has been moved to the standby position.

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

[0083] Specifically, similar to the sleeve 40 of the first embodiment, the sleeve 90 of this embodiment includes a cylindrical main body portion 91, a first annular portion 92 protruding radially inward from a first end portion (the end portion on the first double pipe 10 side) of the main body portion 41 in the pipe axis direction F, and a second annular portion 93 protruding radially outward from a second end portion (the end portion on the second double pipe 20 side) of the main body portion 41 in the pipe axis direction F. However, in this embodiment, the inner diameter of the first annular portion 92 is larger than the outer diameter of the first outer flange 14. When the sleeve 90 is in the connected 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. 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. The inner diameter of the ring plate 100 is larger than the outer diameter of the first inner flange 12. When viewed in the tube axis direction F, the ring plate 100 overlaps both the first outer flange 14 and the first annular portion 92.

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

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

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

[0088] Specifically, an annular first seal material 65 is sandwiched between the ring plate 100 and the first outer flange 14 in the tube axis direction F. The annular first seal material 65 seals between the ring plate 100 and the first outer flange 14. An annular groove for locating the first seal material 65 is formed on one or both of the contact surfaces of the ring plate 100 and the first outer flange 14. It is preferable that the annular groove be 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.

[0089] Furthermore, an annular second seal material 66 is sandwiched between the ring plate 100 and the first annular portion 92 in the tube axis direction F. The annular second seal material 66 seals between the ring plate 100 and the first annular portion 92. An annular groove for disposing the second seal material 66 is formed on one or both of the contact surfaces of the ring plate 100 and the first annular portion 92. It is preferable that the annular groove be present only on the contact surface of the first annular portion 92, among the contact 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 this embodiment will be described. When the sleeve 90 is in the connection position, it covers the first inner flange 12 and the second inner flange 22. Also, when the sleeve 90 is in the connection position, it covers the ring plate 100.

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

[0092] The standby position of the sleeve 90 is between the bellows 31 and the first outer flange 14 in the pipe axis direction F, as in the first embodiment. The sleeve 90 in the connected 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. Furthermore, 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 housed in the sleeve 90. As in the first embodiment, the sleeve 90 in the standby position is supported by the second portion 13b of the first outer pipe 13.

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

[0094] Furthermore, the bolts 56 are removed to release the connection of the ring plate 100 to the first double pipe 10 (more specifically, the first outer flange 14). The ring plate 100 is then moved away from the first outer flange 14 of the first double pipe 10 in the pipe axis direction F to remove the ring plate 100 from the first double pipe 10. That is, the ring plate 100 is moved so that the first inner flange 12 passes inside the ring plate 100. The first sealant 65 and the second sealant 66 are also removed from the first double pipe 10 by moving them away from the first double pipe 10. The first sealant 65 and the second sealant 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 sealant 65 and the second sealant 66 can be replaced with new sealant.

[0095] The method for attaching the seals 65, 66 that seal between the first annular portion 92 and the first outer flange 14 is omitted here because it is the reverse of the method for removing the seals 65, 66. The method for connecting the first double pipe 10 and the second double pipe 20 is the reverse of the method for separating the first double pipe 10 and the second double pipe 20, and therefore the explanation is omitted here.

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

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

[0098] Furthermore, in this embodiment, the first seal 65 and the second seal 66 can be replaced without passing the first outer flange 14 inside the first seal 65 and the second seal 66 .

[0099] Furthermore, since the screw holes 101 and 102 of the ring plate 100 are blind holes, air does not flow into the sealed space S2 through the screw holes 101 and 102. This makes it easy to maintain a vacuum state in the sealed space S2.

[0100] Other Embodiments The present disclosure is not limited to the above-described embodiments, and the configurations thereof may be changed, added, or deleted.

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

[0102] In the above-described embodiments, the double pipe connection structures 1A, 1B, and 1C are connection structures for connecting the equipment 2 to a fluid supply source that supplies a cryogenic fluid to the equipment 2. However, the double pipe connection structures are not limited to this. For example, they can be applied not only to connecting equipment to piping, but also to connecting piping to piping. In other words, the second double pipe does not have to be part of the equipment.

[0103] Furthermore, although the tube axis direction F coincides with the horizontal direction, the tube axis direction F may be inclined relative to the horizontal direction or may coincide with the vertical direction.

[0104] Furthermore, the structures of the first double pipe 10, 70, the second double pipe 20, and the sleeve 40, 90 are not limited to those described in the above embodiment. For example, the first outer flange 14 does not have to be disposed at the tip of the first outer pipe 13. The main body 41, 91 of the sleeve 40, 90 does not have to be cylindrical. For example, the bellows 31 may be provided on the second outer pipe 23 of the second double pipe 20, rather than on the first outer pipe 13 of the first double pipe 10, 70. That is, in the above embodiment, the standby position of the sleeve 40, 90 was located on the first double pipe 10, 70 side where the bellows 31 was located, but the standby position of the sleeve 40, 90 may be located on the second double pipe 20 side. The first double pipe 10 does not have to be provided with a spacer 16.

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

[0106] In the first and third embodiments, the sleeve 40, 90 in the standby position is supported by the second portion 13b of the first outer tube 13. However, a support structure for supporting the sleeve 40 may be disposed on the portion 13b of the first outer tube 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 may extend in the tube axis direction F, and the plurality of guide bars may be arranged at intervals in the circumferential direction. The guide bars may also serve to prevent circumferential rotation of the sleeve 40 relative to the first outer tube 13. The guide bars may be provided with stoppers that limit the range of movement of the sleeve 40 so that it does not move beyond the range between the connection position and the standby position.

[0107] The above-described embodiments and modifications can be combined as appropriate. For example, in the first and third embodiments, the blocking member 75 may be used instead of the blocking member 15, and in the second embodiment, the blocking member 15 may be used instead of the blocking member 75. In the first and third embodiments, the sleeve 40 may be suspended and supported by the support device 80.

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

[0109] Although the description has been given assuming that the pipe axis direction F, which is the direction in which the center lines of the first and second double pipes extend near the connection point of the double pipe connection structure, coincides with the horizontal direction, the pipe axis direction F is not limited to this. For example, the pipe axis direction F may be inclined relative to the horizontal direction or may be vertical.

[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 may be elliptical rather than circular, and the surface of the first outer flange 14 opposite the first annular portion 42 may also be inclined with respect to the direction perpendicular to the tube axis direction F. Because the surfaces of the first outer flange 14 and the first annular portion 42 that sandwich the sealing material 62 are inclined in this manner, the size of the sealing material 62 can be increased while reducing the length of the first outer flange 14 in the direction perpendicular to the tube axis direction F. This makes it easier to pass the first outer flange 14 inside the sealing material 62, making it easier to replace the sealing material 62.

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

[0112] [Aspect 1] A first double pipe including a first inner pipe, a first inner flange protruding from a tip end of the first inner pipe, a first outer pipe exposing the first inner pipe between the first inner flange and 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 a tip end 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 the second inner flange, and a second outer flange protruding from the second outer pipe; and a sleeve 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 while 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 double pipe connection structure, wherein the first outer pipe or the second outer pipe includes a bellows that absorbs positional errors between the first outer flange, the second outer flange, and the sleeve, as well as thermal contraction of the first inner pipe and the second inner pipe.

[0113] According to the above configuration, the first outer pipe or the second outer pipe has a bellows. In other words, since there is no need to provide a bellows to the sleeve, the overall length of the sleeve can be shortened, and the workability when connecting or disconnecting the two double pipes can be improved.

[0114] [Aspect 2] The double pipe connection structure according to Aspect 1, wherein the first outer pipe includes the bellows, the first double pipe includes a blocking member that blocks the space between the first outer pipe and the first inner pipe, the blocking member and the first outer pipe are connected to the bellows on the side opposite to the pipe axis direction from the side on which the first outer flange is located, and the blocking member and the first inner pipe are connected between the bellows and the first inner flange in the pipe axis direction.

[0115] According to the above configuration, the exposed portion of the first inner pipe can be minimized while preventing the displacement of the bellows from being transmitted to the first inner pipe. More specifically, the closing member and the first outer pipe are connected to the bellows on the side opposite to the side where the first outer flange is located in the tube axis direction, so that even if the bellows is displaced, the displacement of the bellows can be prevented from being transmitted to the first inner pipe via the closing member. Furthermore, because the closing member and the first inner pipe are connected between the bellows and the first inner flange in the tube axis direction, the exposed portion of the first inner pipe can be minimized.

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

[0117] This configuration allows the sleeve to be designed without considering interference between the bellows and the sleeve when the sleeve is moved from the connection position to the standby position, which allows the size of the sleeve to be smaller than in a configuration in which the standby position of the sleeve coincides with the position of the bellows in the axial direction of the tube.

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

[0119] According to this configuration, the bellows can be disposed in a position close to the first outer flange, which makes it easier to absorb positional errors between the first outer flange, the second outer flange, and the sleeve.

[0120] [Aspect 5] The double pipe connection structure according to any one of Aspects 1 to 4, wherein the sleeve covers the first outer flange when the sleeve is in the connection position, and the sleeve exposes the first outer flange when the sleeve is in the standby position.

[0121] According to the above configuration, work can be performed on the first outer flange while the sleeve is in the standby position, which makes it easier to perform maintenance on the first outer flange and replace consumables such as sealing materials near the first outer flange.

[0122] [Aspect 6] The double pipe connection structure according to any one of Aspects 1 to 5, wherein the first outer pipe includes the bellows, and the first double pipe 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] A double pipe connection structure according to any one of Aspects 1 to 6, wherein 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 portion and the first outer flange that face each other in the pipe axis direction are each inclined surfaces that are inclined with respect to a direction perpendicular to the pipe axis direction; and the double pipe connection structure further includes an annular sealing material that is sandwiched in the pipe axis direction between the inclined surface of the annular portion and the inclined surface of the first outer flange and that seals between the annular portion and the outer flange.

[0124] According to the above configuration, the surfaces of the annular portion and the first outer flange that sandwich the sealing material are inclined, so that the size of the sealing material can be increased while the length of the first outer flange in the direction perpendicular to the pipe axis direction is reduced, which makes it easier to pass the first outer flange inside the sealing material and to replace the sealing material.

[0125] [Aspect 8] The double pipe connection structure according to any one of Aspects 1 to 7, wherein the sleeve includes: a cylindrical main body portion that encloses the first outer flange as 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 connecting position; and the double pipe connection structure further includes: an annular ring plate that overlaps both the annular portion and the first outer flange as viewed in the pipe axis direction when the sleeve is in the connecting position, and indirectly connects the annular portion and the first outer flange; an annular first sealing material that is sandwiched between the ring plate and the annular portion in the pipe axis direction; and an annular second sealing material that is sandwiched between the ring plate and the first outer flange in the pipe axis direction.

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

[0127] [Aspect 9] A first double pipe including a first inner pipe, a first inner flange protruding from a tip end of the first inner pipe, a first outer pipe exposing the first inner pipe between the first inner flange and 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 a tip end 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 the second inner flange, and a second outer flange protruding from the second outer pipe; a sleeve movable in the axial direction of the first inner flange and the second inner flange between a connection position where the sleeve is 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 sleeve exposes the first inner flange and the second inner flange, the sleeve including: a cylindrical main body portion that contains the first outer flange as viewed in the axial direction of the pipe; 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 pipe when the sleeve is in the connection position; an annular ring plate that overlaps both the annular portion and the first outer flange as viewed in the axial direction of the pipe when the sleeve is in the connection position, and indirectly connects the annular portion and the first outer flange; an annular first sealing material sandwiched between the ring plate and the annular portion in the axial direction of the pipe; and an annular second sealing material sandwiched between the ring plate and the first outer flange in the axial direction of the pipe.

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

[0129] Furthermore, 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, making maintenance of the sleeve and the ring plate easier.

[0130] [Aspect 10] A connection system comprising: the double pipe connection structure according to any one of Aspects 1 to 9; and an assist device that assists movement of the sleeve between the standby position and the connection position, wherein the assist device includes: a rail extending in a direction parallel to the pipe axis direction above the double pipe connection structure; a slider supported on the rail and slidable in the pipe axis direction; and a hanging connection member that connects the slider and the sleeve.

[0131] According to the above configuration, the sleeve can be moved between the standby position and the connection position while being suspended by the support device, which makes it easy to move the sleeve. Also, since the sleeve at the standby position can be suspended by the support device, it is possible to prevent the weight of the sleeve at the standby position from being applied to the first outer tube.

[0132] [Aspect 11] A first double pipe including a first inner pipe, a first inner flange protruding from a tip end of the first inner pipe, a first outer pipe exposing the first inner pipe between the first inner flange and 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 a tip end 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 the second inner flange, and a second outer flange protruding from the second outer pipe; A sleeve 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 while 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 method for replacing a sealing material in a double pipe connection structure comprising an annular sealing material that abuts against the first outer flange and seals between the sleeve and the first outer flange, the method comprising: releasing the fastening of the sleeve to the first double pipe and the second double pipe; moving the sleeve in the connected position away from the second double pipe in the pipe axis direction to expose the first inner flange and the second inner flange; moving the sleeve further away from the second double pipe in the pipe axis direction to expose the first outer flange; and removing the sealing material from the first outer flange and replacing it with a new sealing material.

[0133] According to the above method, the seal material that abuts against the first outer flange can be easily replaced while the first outer flange is exposed.

Claims

1. A first double pipe including 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 second 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; and a sleeve 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 while 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 double pipe connection structure, wherein the first outer pipe or the second outer pipe includes a bellows that absorbs position errors between the first outer flange, the second outer flange, and the sleeve, as well as thermal contraction of the first inner pipe and the second inner pipe.

2. A double pipe connection structure as described in claim 1, wherein the first outer pipe includes the bellows, the first double pipe includes a blocking member that blocks the space between the first outer pipe and the first inner pipe, the blocking member and the first outer pipe are connected on the opposite side of the pipe axis direction to the side on which the first outer flange is located relative to the bellows, and the blocking member and the first inner pipe are connected between the bellows and the first inner flange in the pipe axis direction.

3. A double pipe connection structure as described in claim 1 or 2, wherein the first outer pipe includes the bellows, and the standby position is between the bellows and the first outer flange in the pipe axial direction.

4. A double pipe connection structure as described in claim 1 or 2, wherein the first outer pipe includes the bellows, and the sleeve in the standby position overlaps with the bellows when viewed in a direction perpendicular to the pipe axis direction and is outside the bellows.

5. A double pipe connection structure as described in claim 1 or 2, wherein when the sleeve is in the connection position, the sleeve covers the first outer flange, and when the sleeve is in the standby position, the sleeve exposes the first outer flange.

6. A double pipe connection structure as described in claim 1 or 2, wherein the first outer pipe includes the bellows, and the first double pipe 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 axial direction.

7. The double pipe connection structure described in claim 1 or 2, wherein the sleeve includes: a cylindrical main body portion that contains 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 connected position, and the surface of the annular portion and the surface of the first outer flange that face each other in the pipe axis direction are each inclined surfaces inclined with respect to a direction perpendicular to the pipe axis direction, and the double pipe connection structure further includes an annular sealing material that is sandwiched in the pipe axis direction between the inclined surface of the annular portion and the inclined surface of the first outer flange and seals between the annular portion and the outer flange.

8. The double pipe connection structure according to claim 1 or 2, wherein the sleeve includes: a cylindrical main body portion that contains the first outer flange as 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 connecting position; and the double pipe connection structure further includes: an annular ring plate that overlaps both the annular portion and the first outer flange as viewed in the pipe axis direction when the sleeve is in the connecting position, and indirectly connects the annular portion and the first outer flange; a first annular sealing material that is sandwiched between the ring plate and the annular portion in the pipe axis direction; and a second annular sealing material that is sandwiched between the ring plate and the first outer flange in the pipe axis direction.

9. A first double pipe including 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 second 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 sleeve movable in a pipe axial direction of the first inner flange and the second inner flange between a connection position at which the sleeve is 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 at which the first inner flange and the second inner flange are exposed, the sleeve including a cylindrical main body portion that contains the first outer flange as viewed in the pipe 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 pipe axial direction when the sleeve is in the connection position; an annular ring plate that overlaps both the annular portion and the first outer flange as viewed in the pipe axial direction when the sleeve is in the connection position, and indirectly connects the annular portion and the first outer flange; a first annular sealing material sandwiched between the ring plate and the annular portion in the pipe axial direction; and a second annular sealing material sandwiched between the ring plate and the first outer flange in the pipe axial direction.

10. A connection system comprising: a double pipe connection structure as defined in claim 1 or 9; and an assistance device for assisting movement of the sleeve between the standby position and the connection position, the assistance device including: a rail extending in a direction parallel to the pipe axis direction above the double pipe connection structure; a slider supported on the rail and slidable in the pipe axis direction; and a hanging connection member connecting the slider and the sleeve.

11. A method for replacing a sealant in a double pipe connection structure comprising: a first double pipe including 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 the first outer 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 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 the second inner flange, and a second outer flange protruding from the second outer pipe; a sleeve 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 while covering the first inner flange and the second inner flange, and a standby position exposing the first inner flange and the second inner flange; and an annular sealant abutting against the first outer flange and sealing between the sleeve and the first outer flange, comprising: A method for replacing a sealing material in a double pipe connection structure, comprising: releasing the fastening of the sleeve to the first double pipe and the second double pipe; moving the sleeve in the connected position away from the second double pipe in the pipe axial direction to expose the first inner flange and the second inner flange; moving the sleeve further away from the second double pipe in the pipe axial direction to expose the first outer flange; and removing the sealing material from the first outer flange and replacing it with new sealing material.

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