Insulated double piping unit for liquefied gas and liquefied gas storage ship equipped with same

Abstract

To suppress generation of high stress caused by a thermal contraction difference between an inner pipe and an outer pipe with a simple structure without degrading reliability in liquefied gas transfer, in a heat insulating double pipe for a liquefied gas.SOLUTION: A pipe unit (1) for transferring a liquefied gas is provided with: a heat insulating double pipe (5) composed of an inner pipe (25) in which the liquefied gas passes, and an outer pipe (27) which covers the inner pipe (25) through a heat insulating layer (29) in a state that in the heat insulating double pipe (5), the outer pipe (27) has an expansion / contraction allowing portion (31) for allowing at least change of an axial length; a base (7) having a facing portion facing an outer peripheral surface of the heat insulating double pipe (5); and a restriction member (9) fixed to the base (7), and restricting radial displacement of the outer pipe (27) to the base (7) in a manner that it can be displaced at least in a shaft center direction.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a thermally insulated double piping unit for liquefied gas and a liquefied gas storage ship equipped with the same. [Background technology]

[0002] Conventionally, it has been proposed to use a double-structure vacuum insulated pipe as a pipe for transferring liquefied gas such as liquefied natural gas or liquefied hydrogen, for example, between a liquefied gas carrier and a storage tank on land (see, for example, Patent Document 1). This insulated double pipe has a structure in which an outer pipe covers an inner pipe via an insulating layer made of, for example, a vacuum layer, so that high insulation is obtained and the temperature rise of the low-temperature liquefied gas flowing inside the inner pipe can be effectively suppressed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-004382 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when liquefied gas flows through the thermally insulated double pipe, a difference in thermal contraction occurs between the inner pipe through which the extremely low temperature liquefied gas passes and the outer pipe exposed to the outside air. In order to secure a gap between the inner pipe and the outer pipe, the inner pipe needs to be supported or restrained relative to the outer pipe, and since the above-mentioned difference in thermal contraction, if left unattended, will cause high stress to be generated in the inner pipe and the outer pipe, this difference in thermal contraction needs to be absorbed. However, complicating the structure of the inner pipe through which the liquefied gas passes and which is difficult to inspect, is not preferable because it may impair the reliability of liquefied gas transfer, which is the original function of the thermally insulated double pipe.

[0005] In order to solve the above problems, the object of the present invention is to suppress the occurrence of high stress caused by the difference in thermal contraction between the inner pipe and the outer pipe in an insulated double pipe for liquefied gas with a simple structure without compromising the reliability of liquefied gas transport. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides a thermally insulated double piping unit for liquefied gas, comprising: A piping unit for transporting liquefied gas, comprising: A thermally insulated double pipe including an inner pipe through which the liquefied gas passes and an outer pipe covering the inner pipe via a thermal insulation layer, the outer pipe having an expansion and contraction allowance portion that allows at least a change in axial length; A base having a facing portion facing an outer peripheral surface of the heat-insulating double pipe; a restraining member fixed to the base and restraining the outer tube so as to be displaceable at least in the axial direction relative to the base; Equipped with.

[0007] According to this configuration, first, the expansion and contraction allowance part such as a bellows, which is an effective mechanism for allowing thermal contraction of the inner pipe and absorbing the thermal contraction difference between the inner pipe and the outer pipe, is provided in the outer pipe, not in the inner pipe through which the liquefied gas passes and which is difficult to inspect, so that the reliability of the liquefied gas transfer is ensured. Furthermore, if the expansion and contraction allowance part is provided in the outer pipe, the outer pipe will be displaced in response to the thermal contraction of the inner pipe. However, since the outer pipe is restrained by the restraining member so as to be displaceable, it is possible to prevent the outer pipe from moving excessively due to external factors while suppressing the generation of high stress in the outer pipe. Therefore, in the thermally insulated double pipe for liquefied gas, the generation of high stress caused by the thermal contraction difference between the inner pipe and the outer pipe can be suppressed by a simple structure without impairing the reliability of the liquefied gas transfer.

[0008] The liquefied gas storage ship according to the present invention comprises: The hull and A storage tank for storing liquefied gas installed in the hull; The above-mentioned liquefied gas insulating double piping unit, one end of which is attached to the storage tank; Equipped with.

[0009] When the piping unit is installed in a liquefied gas storage ship, it is particularly important to suppress resonance and excessive movement of the outer pipe provided with an expansion and contraction allowance section due to vibration and deformation of the hull in order to suppress stress generated in the outer pipe. In the liquefied gas storage ship of this configuration, a piping unit having the above-mentioned configuration and effect is installed, so that it is possible to suppress the generation of high stress caused by the thermal contraction difference between the inner pipe and the outer pipe with a simple structure without compromising the reliability of liquefied gas transportation. Effect of the Invention

[0010] As described above, according to the present invention, in an insulated double pipe for liquefied gas, the occurrence of high stress caused by the difference in thermal contraction between the inner pipe and the outer pipe can be suppressed with a simple structure without compromising the reliability of liquefied gas transport. [Brief description of the drawings]

[0011] [Figure 1] 1 is a plan view showing a schematic configuration of a liquefied gas insulating double piping unit according to one embodiment of the present invention and a liquefied gas storage ship equipped with the same. FIG. [Diagram 2] FIG. 2 is a cross-sectional view showing a schematic configuration of the thermally insulated double pipe for liquefied gas and the liquefied gas storage ship shown in FIG. [Diagram 3] FIG. 2 is a vertical cross-sectional view showing a schematic internal structure of the thermally insulated double piping unit for liquefied gas shown in FIG. [Figure 4A] FIG. 2 is a plan view showing a schematic configuration example of the liquefied gas insulating piping unit of FIG. 1 in a room temperature state. [Figure 4B] FIG. 2 is a plan view showing a schematic configuration example of the liquefied gas insulating piping unit of FIG. 1 in a low temperature state. [Diagram 5] FIG. 2 is a cross-sectional view showing the insulated liquefied gas piping unit of FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. Fig. 1 shows a thermally insulated double piping unit for liquefied gas (hereinafter simply referred to as "piping unit") 1 according to one embodiment of the present invention, and a liquefied gas storage ship 3 equipped with the same. The piping unit 1 is used for transporting liquefied gas. The piping unit 1 includes a thermally insulated double piping (hereinafter simply referred to as "piping") 5 having a double-pipe structure, and a base 7 and a restraining member 9, which will be described later, as a support mechanism for supporting the piping 5.

[0013] In this specification, the term "liquefied gas storage ship" refers to a ship having a function of storing liquefied gas. The liquefied gas storage ship 3 in this embodiment is a liquefied gas carrier. However, in addition to liquefied gas carriers, the liquefied gas storage ship 3 also includes, for example, a liquefied gas fuel ship and a bunkering ship that supplies liquefied gas to other ships.

[0014] Specifically, in the illustrated example, the piping 5 is installed in the hull 11 of the liquefied gas storage ship 3 and attached to a storage tank 13 that stores liquefied gas. The piping 5 of the piping unit 1 transfers liquefied gas between the storage tank 13 and the outside, for example, between a liquefied gas storage base on land.

[0015] The liquefied gas transferred through the piping 5 is, for example, liquefied petroleum gas (LPG, about -45°C), liquefied ethylene gas (LEG, about -100°C), liquefied natural gas (LNG, about -160°C), liquefied hydrogen (LH2, about -250°C), or liquefied helium (LHe, about -270°C). In this embodiment, liquefied hydrogen is stored in the storage tank 13, and this liquefied hydrogen is transferred through the piping 5.

[0016] In this embodiment, as shown in FIG. 2, the storage tank 13 is configured as a double-shell tank having an inner tank 15 and an outer tank 17. For example, a vacuum insulation layer is formed between the inner tank 15 and the outer tank 17. However, the configuration of the storage tank 13 is not limited to this example. For example, the storage tank 13 may be a single-shell tank covered with a heat insulating material. In this case, the heat insulating material may be, for example, composed of a plurality of vacuum insulation panels or a plurality of foam panels.

[0017] In this embodiment, the storage tank 13 has a main body 13a which is a portion for storing liquefied gas, and a dome portion 13b which protrudes upward from the main body 13a. One end of the pipe 5 of the pipe unit 1 is attached to the dome portion 13b. In the figure, only one pipe unit 1 is shown for simplification, but a plurality of pipe units 1 may be provided in one storage tank 13. The pipe 5 is extended from the inside of the storage tank 13 to the outside of the storage tank 13 through the dome portion 13b. In this embodiment, a flat dome portion support base 19 which supports the pipe 5 extended from the dome portion 13b is installed on the dome portion 13b via a support structure not shown. As shown in FIG. 1, the pipe 5 coming out of the dome portion 13b passes over the dome portion support base 19, and further passes over the hull 11 (for example, over the upper deck 21), and is extended to, for example, a manifold 23 which serves as a connection portion with the pipe 5 outside the hull 11.

[0018] As shown in Fig. 3, the piping 5 is composed of an inner pipe 25 through which the liquefied gas passes, and an outer pipe 27 that covers the inner pipe 25. A heat insulating layer 29 is formed in the radial gap between the inner pipe 25 and the outer pipe 27. In this embodiment, the heat insulating layer 29 is formed as a vacuum layer. However, the heat insulating layer is not limited to a vacuum layer, and may be, for example, a powder heat insulating layer, a pseudo vacuum layer, a gas layer having heat insulating properties, or the like.

[0019] The outer pipe 27 of the piping 5 has an expansion / contraction portion 31 that allows a change in the axial length. In this embodiment, the outer pipe 27 has a bellows as the expansion / contraction portion 31. In this embodiment, the expansion / contraction portion 31 is provided only on the outer pipe 27, and not on the inner pipe 25. Note that the expansion / contraction portion 31 may be configured to allow, in addition to a change in the axial length of the outer pipe 27, for example, a radial displacement.

[0020] An inner pipe spacer 33 is provided on the outer circumferential surface of the inner pipe 25. The inner pipe spacer 33 maintains the distance between the inner pipe 25 and the outer pipe 27 at a predetermined distance or more.

[0021] In this embodiment, the pipe 5 is formed by connecting a plurality of split pipes 35 in the length direction. Specifically, each split pipe 35 is provided at both ends with a partition wall 37 that closes the insulating layer 29 between the outer pipe 27 and the inner pipe 25. By configuring the pipe 5 with a combination of split pipes 35 having such a structure, the installation work of the pipe 5 is facilitated, and the insulating performance, such as the degree of vacuum of the insulating layer 29, can be easily maintained and managed. Although not shown in the figure, the outer periphery of the part of the pipe 5 where the partition wall 37 is provided may be further covered by a jacket pipe.

[0022] As shown in Fig. 4A, the piping unit 1 includes, as a support mechanism for the piping 5, a base 7 having an opposing portion 7a opposing the outer peripheral surface of the piping 5, and a restraining member 9 fixed to the base 7 and restraining the piping 5 to the base 7. The base 7 is fixed to the equipment on which the piping 5 is installed (in this example, the liquefied gas storage vessel 3). The position of the piping 5 is regulated by the opposing portion 7a of the base 7 and the restraining member 9. Note that Fig. 4A shows a state in which no liquefied gas flows through the piping 5 and no thermal contraction occurs in the inner pipe 25 (hereinafter referred to as the "room temperature state").

[0023] 4A, the piping 5 is bent at approximately right angles at one or more points along the way, and extends from the dome portion 13b to the manifold 23. In other words, the piping 5 has two straight pipe portions (a first straight pipe portion 5a and a second straight pipe portion 5b) that extend linearly, and a bent pipe portion 5c where the first straight pipe portion 5a is connected to the second straight pipe portion 5b so as to be bent.

[0024] In the illustrated example, both the first straight pipe section 5a and the second straight pipe section 5b are provided with an expansion / contraction allowing section 31, and both the first straight pipe section 5a and the second straight pipe section 5b are provided with a restraining member 9. In the following description, for convenience, the restraining member 9 provided in the first straight pipe section 5a will be referred to as the "first restraining member 9A," and the restraining member 9 provided in the second straight pipe section 5b will be referred to as the "second restraining member 9B."

[0025] Moreover, at both ends of the piping 5, both the outer pipe 27 and the inner pipe 25 are fixed to the equipment in which the piping 5 is installed. In this embodiment, one end of the outer pipe 27 and the inner pipe 25 is fixed to the storage tank 13, and the other end is fixed to the manifold 23. Furthermore, as in the illustrated example, when the piping 5 is divided into a plurality of split pipes 35, the outer pipe 27 and the inner pipe 25 may be fixed at both ends of the split pipes 35. In the illustrated example, the partition wall 37 portions of the outer pipe 27 and the inner pipe 25 of the split pipes 35 are also fixed.

[0026] Hereinafter, a configuration example in which the pipe 5 is extended horizontally will be mainly described. In this case, as shown in FIG. 5, the pipe 5 is placed on the facing portion 7a of the base 7. In the illustrated example, the facing portion 7a has a flat surface. However, the support mechanism for the pipe 5 according to this embodiment can also be applied to the pipe 5 extended vertically or in a direction inclined relative to the horizontal direction. In this specification, the facing direction between the pipe 5 and the facing portion 7a of the base 7 (in the example of FIG. 5, the direction perpendicular to the flat surface of the facing portion 7a and the vertical direction) is simply called the "facing direction Z", and the direction perpendicular to the axial direction X of the pipe 1 and the facing direction Z is called the "lateral direction Y". In the following description, the side of the facing direction Z on which the pipe 5 is arranged as viewed from the base 7 is called the "upper side" for convenience.

[0027] 5, the restraining member 9 is configured to restrain the outer tube 27 so as to be displaceable in both the axial direction X and the lateral direction Y. In other words, the restraining member 9 has portions that regulate the position of the outer tube 27 placed on the base 7 via gaps at least above and on both sides (lateral direction Y). Preferably, the restraining member 9 has a shape in which these portions are integrally and continuously formed, such as a U-shape.

[0028] Specifically, in the illustrated example, the restraining member 9 is formed as a U-shaped bolt. This restraining member 9 straddles the pipe 5 placed on the base 7, and both ends are fixed to the base 7 by nuts 39. The dimensions in each direction of the inner circumferential surface of the restraining member 9 are set to be larger than the dimensions in each direction of the outer circumferential surface of the outer pipe 27 when the pipe 5 is placed on the base 7 and the restraining member 9 is fixed to the base 7. In other words, the shape and dimensions of the restraining member 9 are set so that the outer circumferential surface of the outer pipe 27 does not contact any part of the inner circumferential surface of the restraining member 9 (i.e., so that a gap is formed between the outer pipe 27 and the restraining member 9) when the pipe 5 is disposed at the center of the restraining member 9 in the horizontal direction Y in a cross-sectional view.

[0029] In the following description, when the piping 5 is positioned at the center of the restraining member 9 in the horizontal direction Y in a cross-sectional view, the gap in the opposing direction Z with the restraining member 9 at the top of the piping 5 is referred to as the upper gap G1, and the two gaps in the horizontal direction Y at the sides of the piping 5 are referred to as the side gap G2.

[0030] In this embodiment, the upper gap G1 is set to a minimum size capable of preventing resonance that may occur in the outer pipe 27. Specifically, the size of the upper gap G1 is, for example, 1 to 2 mm for a pipe 5 having a diameter of 125 mm. On the other hand, the side gap G2 (here, as an example, the side gap G2 between the first straight pipe portion 5a and the first restraining member 9A) is set to a size corresponding to the amount of displacement due to thermal contraction of the second straight pipe portion 5b connected via the bent pipe portion 5c.

[0031] That is, when liquefied gas flows through the pipe 5 shown in FIG. 4B from the normal temperature state shown in FIG. 4A (hereinafter, this state will be referred to as the "low temperature state"), the inner pipe 25 undergoes thermal contraction, and the displacement of the inner pipe 25 due to the thermal contraction displaces the outer pipe 27 having the expansion and contraction allowance portion 31 in the direction shown by the arrow in the figure via the inner pipe spacer 33. In the illustrated example, the outer pipe 27 displaces in the axial direction of the second straight pipe portion 5b in response to the thermal contraction of the inner pipe 25 of the second straight pipe portion 5b. The first straight pipe portion 5a extending in a direction substantially perpendicular to the second straight pipe portion 5b displaces in the lateral direction Y of FIG. 5 to a position shown by a broken line by an amount corresponding to the amount of displacement in the axial direction of the second straight pipe portion 5b. The side gap G2 between the first straight pipe portion 5a and the first restraining member 9A is set to a size that allows this displacement and restricts displacement in the lateral direction Y that is greater than this amount of displacement. Specifically, the size of the side gap G2 is, for example, 10 to 20 mm for a pipe 5 having a diameter of 125 mm.

[0032] In the illustrated example, both the first straight pipe section 5a and the second straight pipe section 5b (FIG. 4A) have the expansion / contraction allowing section 31, and therefore the size of the side gap G2 for both straight pipe sections is set as described above.

[0033] However, the sizes of the upper gap G1 and the side gap G2 are not limited to these examples. Furthermore, in a room temperature state, the side gap G2 may be formed only on one side in the lateral direction Y (i.e., the outer tube 27 and the restraining member 9 may be in contact on the other side), or the side gap G2 may not be formed and only the upper gap G1 may be formed. Furthermore, the shape of the restraining member 9 is not limited to the example shown. The method of fixing the restraining member 9 to the base 7 is not limited to screwing as in the example shown, and may be, for example, welding.

[0034] In the example shown in FIG. 4A, when the pipe 5 is bent via the bent pipe section 5c, only the first straight pipe section 5a may have the expansion and contraction allowable section 31, and the second straight pipe section 5b may be provided with the second restraining member 9B. In this case, the second restraining member 9B is configured to restrain the second straight pipe section 5b so as to be displaceable in the axial direction of the second straight pipe section 5b and in the lateral direction perpendicular to the facing direction. In addition, when only the first straight pipe section 5a has the expansion and contraction allowable section 31, the first straight pipe section 5a may also be provided with the first restraining member 9A. In this case, the first restraining member 9A is configured to restrain the first straight pipe section 5a so as to be displaceable at least in the axial direction of the first straight pipe section 5a.

[0035] Also, unlike the illustrated example, the pipe 5 may have only the straight pipe portion 5a without the bent pipe portion 5c. In this case, the restraining member 9 is configured to restrain the pipe 5 so as to be displaceable at least in the axial direction of the pipe.

[0036] In this embodiment, in both the room temperature state shown in Fig. 4A and the low temperature state in which the inner pipe 25 is maximally contracted shown in Fig. 4B, at least a part of the inner pipe spacer 33 is disposed so as to be located within the range of the axial width of the restraining member 9. That is, the axial position of the restraining member 9 overlaps with the inner pipe spacer 33 in the room temperature state.

[0037] As described above, the thermal contraction occurring in the inner pipe 25 causes the outer pipe 27 to be displaced via the inner pipe spacer 33. Therefore, by matching the position of the restraining member 9 with the position of the inner pipe spacer 33, the outer pipe 27 can be made to reliably follow the thermal contraction of the inner pipe 25. As a result, it is possible to suppress the stress occurring in the inner pipe 25 and the outer pipe 27. However, the relative positional relationship between the inner pipe spacer 33 and the restraining member 9 is not limited to this example.

[0038] As shown in FIG. 5, a low-friction member 41 is interposed between the pipe 5 and the base 7. The low-friction member 41 is a flat plate-shaped member having a smaller friction coefficient than the mounting surface of the opposing portion 7a of the base 7. Specifically, in this embodiment, a resin pad made of, for example, polyethylene terephthalate (PET) resin is used as the low-friction member 41. The material for forming the low-friction member 41 is not limited to this example, and may be other types of resin such as polyethylene (PE) and polytetrafluoroethylene (PTFE), or may be a material other than resin such as wood.

[0039] In the illustrated example, the low-friction member 41 is fixed to the base 7 by a U-shaped bolt, which is the restraining member 9. However, the method of fixing the low-friction member 41 to the base 7 is not limited to this. Also, in the illustrated example, the low-friction member 41 is formed as a member separate from the base 7 and then connected to the base 7, but the low-friction member 41 may be provided integrally with a portion of the base 7 that comes into contact with the pipe 5.

[0040] In this way, by interposing the low-friction member 41 between the piping 5 and the base 7, the displacement of the outer pipe 27 can be facilitated and the outer pipe 27 can be reliably caused to follow the thermal contraction of the inner pipe 25. However, it is not essential to interpose the low-friction member 41 between the piping 5 and the base 7.

[0041] The base 7 may be any structure having a portion on which the piping 5 can be placed when the piping 5 extends horizontally and having sufficient strength to support the piping 5. For example, in the illustrated example in which the piping unit 1 is installed on the hull 11, the above-mentioned dome support 19 may be used as the base 7 around the storage tank 13. Also, in a location on the hull 11 away from the storage tank 13, the upper deck 21 of the hull 11 may be used as the base 7. Also, the base 7 does not necessarily have to have a flat surface as illustrated. For example, the base 7 may be a spherical structure such as the dome portion 13b, or a tower-shaped structure.

[0042] According to the liquefied gas heat-insulating double pipe unit 1 according to the present embodiment described above, first, the expansion and contraction allowing portion 31 such as a bellows, which is an effective mechanism for allowing the thermal contraction of the inner pipe 25 and absorbing the thermal contraction difference between the inner pipe 25 and the outer pipe 27, is provided in the outer pipe 27, not in the inner pipe 25 through which the liquefied gas passes and which is difficult to inspect, so that the reliability of the liquefied gas transfer is ensured. In addition, if the expansion and contraction allowing portion 31 is provided in the outer pipe 27, the outer pipe 27 will be displaced in response to the thermal contraction of the inner pipe 25. However, since the outer pipe 27 is restrained by the restraining member 9 so as to be displaceable, it is possible to prevent the outer pipe 27 from moving excessively due to an external factor while suppressing the generation of high stress in the outer pipe 27. Therefore, in the liquefied gas heat-insulating double pipe 5, the generation of high stress caused by the thermal contraction difference between the inner pipe 25 and the outer pipe 27 can be suppressed by a simple structure without impairing the reliability of the liquefied gas transfer.

[0043] Furthermore, when the piping unit 1 is installed in a liquefied gas storage ship, it is particularly important in order to suppress the stress generated in the outer pipe 27, which is provided with the expansion and contraction allowance section 31, by suppressing resonance and excessive movement caused by vibration and deformation of the hull 1. In the liquefied gas storage ship 3 according to this embodiment, the piping unit 1 having the above-mentioned configuration and effect is installed, so that the generation of high stress caused by the thermal contraction difference between the inner pipe 25 and the outer pipe 27 can be suppressed with a simple structure without compromising the reliability of liquefied gas transfer.

[0044] It should be noted that the expandable / contractable portion 31 of the outer pipe 27 in the piping unit 1 and the corresponding restraining member 9 and base 7 do not need to be provided over the entire piping 5, and may be provided only in a portion thereof.

[0045] Although the preferred embodiment of the present invention has been described above with reference to the drawings, various additions, modifications, and deletions can be made without departing from the spirit of the present invention. Therefore, such additions, modifications, and deletions are also included in the scope of the present invention. [Explanation of symbols]

[0046] 1. Insulated double piping unit for liquefied gas 3. Liquefied gas storage vessel 5. Insulated double piping 5a 1st straight pipe section 5b 2nd straight pipe section 5c Bent pipe section 7 Foundation 9 Restraining member 25 Inner tube 27 Outer tube 31 Expandable section 33 Inner pipe spacer

Claims

1. A piping unit for transporting liquefied gas, comprising: A thermally insulated double pipe including an inner pipe through which the liquefied gas passes and an outer pipe covering the inner pipe via a vacuum layer, the outer pipe having an expansion and contraction allowance portion that allows at least a change in axial length; A base having a facing portion facing an outer peripheral surface of the heat-insulating double pipe; a restraining member fixed to the base and restraining the outer tube so as to be displaceable at least in the axial direction relative to the base; Equipped with an inner pipe spacer is provided on an outer circumferential surface of the inner pipe to maintain a distance between the inner pipe and the outer pipe equal to or greater than a predetermined distance; An insulated double piping unit for liquefied gas, wherein at least a portion of the inner pipe spacer is positioned within the axial width range of the restraint member in both normal temperature and low temperature conditions.

2. The liquefied gas heat-insulating double piping unit according to claim 1, The heat-insulating double pipe has a first straight pipe section and a second straight pipe section extending linearly, and a bent pipe section in which the first straight pipe section is bent relative to the second straight pipe section, At least the first straight pipe portion has the expansion / contraction allowing portion, The restraining member is provided in the second straight pipe section, and the restraining member restrains the second straight pipe section so as to be displaceable in a lateral direction perpendicular to the axial direction of the second straight pipe section and the opposing direction of the thermally insulated double pipe and the base. Insulated double piping unit for liquefied gas.

3. The liquefied gas heat-insulating double piping unit according to claim 1 or 2, The heat insulating double pipe further includes a low-friction member having a flat plate shape interposed between the heat insulating double pipe and the base, the low-friction member having a friction coefficient smaller than that of the base, at least a surface of the low-friction member that is in contact with the heat insulating double pipe. Insulated double piping unit for liquefied gas.

4. The liquefied gas heat-insulating double piping unit according to any one of claims 1 to 3, The restraining member is formed between the outer pipe and the restraining member such that a gap is formed between the outer pipe and the heat-insulating double pipe in a direction in which the heat-insulating double pipe and the base face each other. Insulated double piping unit for liquefied gas.

5. The hull and A storage tank for storing liquefied gas installed in the hull; The liquefied gas insulating double piping unit according to any one of claims 1 to 4, one end of which is attached to the storage tank; A liquefied gas storage vessel equipped with:

Images