Insulated double-pipe piping unit for liquefied gas and liquefied gas storage ship having the same

Abstract

In a piping unit (1) for transferring liquefied gas, the piping unit (1) is provided with: a double-pipe heat-insulating pipe (5) composed of an inner pipe (25) through which the liquefied gas passes and an outer pipe (27) covering the inner pipe (25) with a heat-insulating layer (29) interposed therebetween, the outer pipe (27) having a stretch-allowing portion (31) allowing at least a change in axial length; a base (7) having an opposing portion opposing an outer peripheral surface of the double-pipe heat-insulating pipe (5); and a restraining member (9) fixed to the base (7) and restraining the outer pipe (27) so as to be at least displaceable in the axial direction with respect to the base (7).

Description

[0001] Related applications

[0002] This application claims priority to Japanese Patent Application No. 2020-173394, filed on October 14, 2020, and references and incorporates the entire contents of which form part of this application. Technical Field

[0003] The present invention relates to an insulated double-layer piping unit for liquefied gas and an liquefied gas storage vessel having the insulated double-layer piping unit for liquefied gas. Background Technology

[0004] Conventionally, for piping used to move liquefied gases such as liquefied natural gas or liquefied hydrogen between, for example, liquefied gas transport ships and storage tanks on land, a solution using a double-layered vacuum insulated pipe has been proposed (see, for example, Patent Document 1). This insulated double-layered piping has a structure in which an outer pipe covers an inner pipe through an insulation layer, for example, a vacuum layer, thus achieving high insulation performance and effectively suppressing the temperature rise of the low-temperature liquefied gas flowing inside the inner pipe.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2015-004382 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] However, when liquefied gas (LPG) flows into insulated double-layer piping, a thermal contraction difference occurs between the inner pipe through which the extremely low-temperature LPG passes and the outer pipe exposed to the outside air. To ensure a clearance between the inner and outer pipes, the inner pipe needs to be supported or constrained relative to the outer pipe. If this thermal contraction difference is left unchecked, it can lead to high stress in both the inner and outer pipes; therefore, it needs to be absorbed. However, the complex construction of the inner pipe, which allows LPG to pass through and is difficult to inspect, may compromise the original function of the insulated double-layer piping—the reliability of LPG delivery—and is therefore not preferred.

[0010] In order to solve the above-mentioned problems, the object of the present invention is to suppress the generation of high stress caused by the thermal contraction difference between the inner and outer pipes in the insulated double-layer piping for liquefied gas without compromising the reliability of liquefied gas transfer, through a simple structure.

[0011] Methods for solving problems

[0012] To achieve the above objectives, the liquefied gas insulated double-layer piping unit of the present invention is a piping unit for transferring liquefied gas, wherein the liquefied gas insulated double-layer piping unit comprises: an insulated double-layer piping consisting of an inner pipe through which the liquefied gas passes and an outer pipe covering the inner pipe with an insulation layer, the outer pipe having a telescoping allowable portion that allows at least axial length variation; a base having a counter portion facing the outer periphery of the insulated double-layer piping; and a restraining member fixed to the base, constraining the outer pipe relative to the base so that it can be displaced at least along the axial direction.

[0013] According to this structure, firstly, a expansion-allowing part, such as a bellows, which effectively absorbs the difference in thermal contraction between the inner and outer pipes to accommodate the thermal contraction of the inner pipe, is provided on the outer pipe, rather than on the inner pipe through which liquefied gas passes and which is difficult to inspect. This ensures the reliability of liquefied gas transfer. Furthermore, when the expansion-allowing part is provided on the outer pipe, the outer pipe shifts according to the thermal contraction of the inner pipe, but is constrained by the aforementioned restraining member to allow for displacement. Therefore, it is possible to suppress the generation of high stress in the outer pipe while preventing excessive movement of the outer pipe due to external factors. Thus, with a simple construction, in insulated double-layer piping for liquefied gas, the generation of high stress caused by the difference in thermal contraction between the inner and outer pipes can be suppressed with a simple structure without compromising the reliability of liquefied gas transfer.

[0014] The liquefied gas storage vessel of the present invention comprises: a hull; a storage tank for storing liquefied gas disposed in the hull; and the aforementioned insulated double-layer piping unit for liquefied gas, one end of which is installed in the storage tank.

[0015] In the case of piping units installed on liquefied gas storage vessels, for outer pipes equipped with expansion joints, suppressing resonance or excessive movement caused by hull vibration or deformation is particularly important in suppressing stress generated in the outer pipes. In liquefied gas storage vessels with this structure, due to the piping units having the aforementioned structure and effects, the generation of high stress caused by the thermal contraction difference between the inner and outer pipes can be suppressed with a simple structure without compromising the reliability of liquefied gas transfer.

[0016] Any combination of at least two structures disclosed in the claims and / or description and / or drawings is also included in this invention. In particular, any combination of two or more claims is also included in this invention. Attached Figure Description

[0017] The invention can be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are for mere illustration and description and should not be used to define the scope of the invention. The scope of the invention is defined by the appended claims. In the drawings, the same reference numerals in the plurality of drawings denote the same or equivalent parts.

[0018] Figure 1 This is a top view showing a schematic structure of a liquefied gas insulated double-layer piping unit for liquefied gas and a liquefied gas storage vessel having the liquefied gas insulated double-layer piping unit according to an embodiment of the present invention.

[0019] Figure 2 It is shown Figure 1 A cross-sectional view of the schematic structure of an insulated double-layer piping unit for liquefied gas and a liquefied gas storage vessel.

[0020] Figure 3 It is shown Figure 1 A longitudinal sectional view of the general internal structure of a double-layer insulated piping unit for liquefied gas.

[0021] Figure 4A It is shown schematically. Figure 1 A top view of an example configuration structure of an insulated piping unit for liquefied petroleum gas under normal temperature conditions.

[0022] Figure 4B It is shown schematically. Figure 1 A top view of an example of the configuration structure of an insulated piping unit for liquefied gas under low-temperature conditions.

[0023] Figure 5 It is shown Figure 1 A cross-sectional view of an insulated piping unit for liquefied petroleum gas. Detailed Implementation

[0024] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1 This invention illustrates an insulated double-layer piping unit (hereinafter referred to as "piping unit") 1 for liquefied gas and an liquefied gas storage vessel 3 having the piping unit, according to one embodiment of the present invention. The piping unit 1 is used for the transfer of liquefied gas. The piping unit 1 has an insulated double-layer piping (hereinafter referred to as "piping") 5 including a double-pipe structure, and a base 7 and a restraining member 9, described later, as a support mechanism for supporting the piping 5.

[0025] In addition, in this specification, "liquefied gas storage vessel" refers to a vessel with the function of storing liquefied gas. The liquefied gas storage vessel 1 in this embodiment is a liquefied gas transport vessel. However, in addition to liquefied gas transport vessels, liquefied gas fuel vessels, fuel carriers that supply liquefied gas to other vessels, etc., are also included in the category of liquefied gas storage vessels.

[0026] Specifically, in the illustrated example, piping 5 is installed in storage tank 13, which is located on the hull 11 of the liquefied gas storage vessel 3 and stores liquefied gas. Liquefied gas is transferred between storage tank 13 and its external environment, such as a land-based liquefied gas storage site, via piping 5 of piping unit 1.

[0027] The liquefied gases transferred by pipe 5 include, for example, liquefied petroleum gas (LPG, approximately -45°C), liquefied ethylene gas (LEG, approximately -100°C), liquefied natural gas (LNG, approximately -160°C), liquefied hydrogen (LH2, approximately -250°C), and liquefied helium (LHe, approximately -270°C).

[0028] In this embodiment, liquefied hydrogen is stored in storage tank 13 and is transferred via piping 5.

[0029] In this embodiment, such as Figure 2 As shown, the storage tank 13 is configured as a double-shell tank with 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 structure of the storage tank 13 is not limited to this example. For example, the storage tank 13 may also be a single-shell tank covered with insulation material. In this case, the insulation material may be composed of multiple vacuum insulation panels or multiple foam panels.

[0030] In this embodiment, the storage tank 13 has a main body 13a that serves as a liquefied gas storage portion and a domed top 13b protruding upward from the main body 13a. One end of the pipe 5 of the piping unit 1 is mounted on the domed top 13b. Furthermore, for simplicity, only one piping unit 1 is shown in this figure, but multiple piping units 1 can be provided on one storage tank 13. The pipe 5 extends from the interior of the storage tank 13 through the domed top 13b to the exterior of the storage tank 13. In this embodiment, a flat domed top support platform 19 (not shown) is provided on the domed top 13b via a support structure to support the pipe 5 extending from the domed top 13b. Figure 1 As shown, the pipe 5 extending from the dome 13b passes through the dome support 19 and then through the hull 11 (e.g., the upper deck 21) to a manifold 23 that serves as a connection point to the pipe 5 outside the hull 11.

[0031] like Figure 3 As shown, piping 5 consists of an inner pipe 25 through which liquefied gas passes and an outer pipe 27 covering the inner pipe 25. A heat insulation layer 29 is formed in the radial gap between the inner pipe 25 and the outer pipe 27. In this embodiment, the heat insulation layer 29 is formed as a vacuum layer. However, the heat insulation layer is not limited to a vacuum layer; for example, it can also be a powder heat-insulating layer, a pseudo-vacuum layer, a gas layer with heat insulation properties, etc.

[0032] The outer pipe 27 of the piping 5 has a telescoping allowance 31 that allows for changes in length along the axial direction. In this specification, "axial direction" refers to the axial direction of the piping 5 unless otherwise specified. In this embodiment, the outer pipe 27 has a bellows as the telescoping allowance 31. In this embodiment, the telescoping allowance 31 is provided only on the outer pipe 27 and not on the inner pipe 25. Furthermore, the telescoping allowance 31 may also be configured to allow, in addition to allowing changes in the axial length of the outer pipe 27, also radial displacement.

[0033] An inner tube spacer 33 is provided on the outer circumferential surface of the inner tube 25. The inner tube spacer 33 maintains the distance between the inner tube 25 and the outer tube 27 at a predetermined distance or more.

[0034] In this embodiment, the piping 5 is formed by connecting multiple segmented pipe bodies 35 along its length. Specifically, each segmented pipe body 35 has a partition wall 37 at both ends that seals the insulation layer 29 between the outer pipe 27 and the inner pipe 25. By assembling the piping 5 from a combination of segmented pipe bodies 35 with this structure, the installation of the piping 5 becomes easier, and the maintenance and management of insulation performance, such as the vacuum level of the insulation layer 29, becomes easier. Although not shown in the figure, the outer periphery of the portion of the piping 5 with the partition wall 37 can also be further covered by a sleeve.

[0035] like Figure 4A As shown, the piping unit 1 includes: a base 7 having a facing portion 7a opposite to the outer periphery of the piping 5 as a support mechanism for the piping 5; and a restraining member 9 fixed to the base 7 to restrain the piping 5 relative to the base 7. The base 7 is fixed relative to the equipment on which the piping 5 is installed (in this example, an LPG storage vessel 3). The position of the piping 5 is restricted by the facing portion 7a of the base 7 and the restraining member 9. Furthermore, Figure 4A This shows a state where liquefied gas is not flowing in pipe 5 and inner pipe 25 is not thermally contracted (hereinafter referred to as "normal temperature state").

[0036] exist Figure 4A In the example shown, the conduit 5 extends from the dome 13b to the manifold 23 in a state where it is bent at one or more points along its length at approximately a right angle. In other words, the conduit 5 has two straight pipe sections (first straight pipe section 5a and second straight pipe section 5b) that extend in a straight line and a bent pipe section 5c connected in such a way that the first straight pipe section 5a is bent relative to the second straight pipe section 5b.

[0037] Furthermore, in the illustrated example, both the first straight pipe section 5a and the second straight pipe section 5b are provided with telescopic allowances 31, and both the first straight pipe section 5a and the second straight pipe section 5b are provided with restraint members 9. In the following description, for convenience, the restraint member 9 provided in the first straight pipe section 5a will be referred to as "first restraint member 9A", and the restraint member 9 provided in the second straight pipe section 5b will be referred to as "second restraint member 9B".

[0038] Additionally, at both ends of the piping 5, the outer pipe 27 and the inner pipe 25 are also fixed to the equipment on 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 shown in the illustrated example, when the piping 5 is divided into multiple segmented pipe bodies 35, the outer pipe 27 and the inner pipe 25 can also be fixed at both ends of the segmented pipe body 35. In the illustrated example, the partition wall 37 portion of the outer pipe 27 and the inner pipe 25 of the segmented pipe body 35 is also fixed.

[0039] The following mainly describes a structural example where the piping 5 extends horizontally. In this case, as... Figure 5 As shown, the pipe 5 is mounted on the opposing portion 7a of the base 7. In the illustrated example, the opposing portion 7a has a flat surface. However, the support mechanism for the pipe 5 of this embodiment can also be applied to pipes 5 extending in a vertical direction and pipes 5 extending in a direction inclined relative to the horizontal direction. In this specification, the opposing direction of the pipe 5 and the opposing portion 7a of the base 7 (in...) Figure 5 In the example, the direction perpendicular to the flat surface of the opposing part 7a (vertical direction) is simply referred to as "opposing direction Z". In addition, the direction perpendicular to the axial direction X of the pipe 1 and the opposing direction Z is referred to as "lateral direction Y". Furthermore, in the following description, for convenience, the side on the opposing direction Z where the pipe 5 is located when viewed from the base 7 is referred to as "upper".

[0040] like Figure 5 As shown, the constraint member 9 is configured to constrain the outer tube 27 to be displaceable in any direction, either the axial direction X or the transverse direction Y. In other words, the constraint member 9 has portions that limit the position of the outer tube 27 mounted on the base 7, at least above and to the sides (transverse Y). Preferably, the constraint member 9 has a shape, such as a U-shape, in which these portions are integrally and continuously formed.

[0041] Specifically, in the illustrated example, the constraint member 9 is formed as a U-shaped bolt. The constraint member 9, spanning the pipe 5 mounted on the base 7, is fixed to the base 7 at both ends by nuts 39. The dimensions of the inner circumferential surface of the constraint member 9 in each direction are set such that, with the pipe 5 mounted on the base 7 and the constraint member 9 fixed to the base 7, it is larger than the dimensions of the outer circumferential surface of the outer pipe 27 in each direction. That is, the shape and dimensions of the constraint member 9 are set such that, when viewed in cross-section, the pipe 5 is positioned at the center of the transverse Y-axis of the constraint member 9, and the outer circumferential surface of the outer pipe 27 does not contact any part of the inner circumferential surface of the constraint member 9 (i.e., a gap is formed between the outer pipe 27 and the constraint member 9).

[0042] In the following description, when the pipe 5 is positioned in the center of the transverse Y direction of the constraint member 9 when viewed from the cross-section, the gap between the uppermost part of the pipe 5 and the constraint member 9 in the opposite direction Z is called the upper gap G1, and the two gaps in the transverse Y direction on the side of the pipe 5 are called the side gaps G2.

[0043] In this embodiment, the upper gap G1 is set to a minimum size that can prevent resonance from occurring in the outer tube 27. Specifically, the size of the upper gap G1 is, for example, 1 mm to 2 mm relative to the diameter of the 125 mm pipe 5. On the other hand, the lateral gap G2 (here, the lateral gap G2 between the first straight pipe section 5a and the first restraint member 9A is taken as an example) is set to a size corresponding to the amount of displacement caused by the thermal contraction of the second straight pipe section 5b connected via the bent pipe section 5c.

[0044] That is, when from Figure 4A The room temperature state shown is based on Figure 4B When liquefied gas flows in the pipe 5 shown (hereinafter, this state is referred to as the "low-temperature state"), thermal contraction occurs in the inner pipe 25. The displacement caused by the thermal contraction of the inner pipe 25 causes the outer pipe 27, which has a telescoping allowance 31, to move in the direction indicated by the arrow in the figure via the inner pipe spacer 33. In the illustrated example, the outer pipe 27 moves in the axial direction of the second straight pipe section 5b in accordance with the thermal contraction of the inner pipe 25 of the second straight pipe section 5b. The amount of displacement of the first straight pipe section 5a, which extends in a direction substantially perpendicular to the second straight pipe section 5b, in the axial direction of the second straight pipe section 5b corresponds to the displacement of the inner pipe 25. Figure 5 The lateral Y-axis displacement is moved to the position shown by the dashed line. The lateral clearance G2 between the first straight pipe section 5a and the first restraint member 9A is set to allow this displacement and limit the lateral Y-axis displacement exceeding this amount. Specifically, the size of the lateral clearance G2 is, for example, 10mm to 20mm relative to the diameter of the pipe 5 (125mm).

[0045] In the illustrated example, due to the first straight pipe section 5a and the second straight pipe section 5b ( Figure 4AAll of them have a telescopic allowable part 31, so the size of the lateral clearance G2 of any straight tube section is set as described above.

[0046] However, the sizes of the upper gap G1 and the side gap G2 are not limited to these examples. Furthermore, at room temperature, the side gap G2 may be formed only on one side of the transverse Y (i.e., on the other side where the outer tube 27 contacts the restraining member 9), or the side gap G2 may not be formed, and only the upper gap G1 may be formed. Additionally, the shape of the restraining member 9 is not limited to the illustrated example. The method of fixing the restraining member 9 to the base 7 is not limited to the threaded fixing of the illustrated example; for example, it could also be a welding-based fixing.

[0047] In addition, Figure 4A In the example shown, if the pipe 5 is bent via the bend 5c, only the first straight pipe section 5a has a telescoping allowance 31, and a second restraining member 9B is provided on the second straight pipe section 5b. In this case, the second restraining member 9B is configured to restrain the second straight pipe section 5b so that it can move laterally in the axial direction and perpendicular to the opposite direction. Alternatively, if only the first straight pipe section 5a has a telescoping allowance 31, a first restraining member 9A may be provided on the first straight pipe section 5a. In this case, the first restraining member 9A is configured to restrain the first straight pipe section 5a so that it can move at least in the axial direction.

[0048] Alternatively, unlike the example shown, the pipe 5 may not have a bent section 5c and may only have a straight section 5a. In this case, the restraining member 9 is configured to restrain the pipe 5 so that it can be displaced at least along the axial direction of the pipe.

[0049] Furthermore, in this embodiment, even when Figure 4A The room temperature state shown and Figure 4B In any of the low-temperature states where the inner tube 25 is maximally contracted, at least a portion of the inner tube spacer 33 is also configured to lie within the axial width of the constraint member 9. That is, the axial position of the constraint member 9 overlaps with the inner tube spacer 33 at room temperature.

[0050] As described above, the thermal contraction generated in the inner tube 25 causes displacement of the outer tube 27 via the inner tube spacer 33. Therefore, by aligning the position of the restraining member 9 with the position of the inner tube spacer 33, the outer tube 27 can reliably follow the thermal contraction of the inner tube 25. As a result, stress generated in the inner tube 25 and the outer tube 27 can be suppressed. However, the relative positional relationship between the inner tube spacer 33 and the restraining member 9 is not limited to this example.

[0051] like Figure 5As shown, a low-friction component 41 is sandwiched between the pipe 5 and the base 7. The low-friction component 41 is a flat plate-shaped component having a coefficient of friction smaller than that of the mounting surface of the opposing portion 7a of the base 7. Specifically, in this embodiment, a resin pad formed of, for example, polyethylene terephthalate (PET) resin is used as the low-friction component 41. The material forming the low-friction component 41 is not limited to this example; for example, it may be other types of resins such as polyethylene (PE) or polytetrafluoroethylene (PTFE), or even materials other than resins such as wood.

[0052] In the illustrated example, the low-friction component 41 is fixed to the base 7 by a U-shaped bolt that serves as a constraint component 9. However, the method of fixing the low-friction component 41 to the base 7 is not limited to this. In addition, in the illustrated example, the low-friction component 41 is connected to the base 7 after being formed as a separate component from the base 7, but the low-friction component 41 may also be integrally provided with the portion of the base 7 that contacts the piping 5.

[0053] Thus, by sandwiching a low-friction component 41 between the pipe 5 and the base 7, the displacement of the outer pipe 27 can be facilitated, thereby reliably following the thermal contraction of the inner pipe 25. However, sandwiching the low-friction component 41 between the pipe 5 and the base 7 is not necessary.

[0054] The base 7 can be any structure as long as it has a portion capable of supporting the pipe 5 when it extends horizontally and has sufficient strength to support the pipe 5. For example, in the example shown in the illustration where the pipe unit 1 is installed on the hull 11, the aforementioned domed support platform 19 can also be used as the base 7 around the storage tank 13. Alternatively, the upper deck 21 of the hull 11 can be used as the base 7 in a location on the hull 11 away from the storage tank 13. Furthermore, the base 7 does not necessarily have to have a flat surface as illustrated. For example, the base 7 can be a spherical structure like the dome 13b, or it can be a frame-like structure.

[0055] According to the above-described embodiment of the insulated double-layer piping unit 1 for liquefied gas, firstly, a expansion-allowing portion 31, similar to a bellows, is provided on the outer pipe 27 as a mechanism that effectively absorbs the difference in thermal contraction between the inner pipe 25 and the outer pipe 27 to allow for thermal contraction of the inner pipe 25, instead of being provided on the inner pipe 25 through which liquefied gas passes and which is difficult to inspect. Therefore, the reliability of liquefied gas transfer can be ensured. Furthermore, when the expansion-allowing portion 31 is provided on the outer pipe 27, the outer pipe 27 shifts according to the thermal contraction of the inner pipe 25. However, since the outer pipe 27 is constrained by the restraint member 9 to be able to shift, it is possible to suppress the generation of high stress in the outer pipe 27 while preventing excessive movement of the outer pipe 27 due to external factors. Therefore, with a simple structure, in the insulated double-layer piping 5 for liquefied gas, the generation of high stress caused by the difference in thermal contraction 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.

[0056] Furthermore, when the piping unit 1 is installed on the liquefied gas storage vessel, it is particularly important to suppress resonance or excessive movement caused by vibration or deformation of the hull 1 in the outer pipe 27, which is equipped with a telescoping allowance 31, in order to suppress the stress generated in the outer pipe 27. In the liquefied gas storage vessel 3 of this embodiment, since the piping unit 1 with the above-described structure and effects is provided, 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.

[0057] In addition, the expansion and contraction allowance part 31 of the outer pipe 27 in the piping unit 1 and its corresponding constraint part 9 and base 7 do not need to be installed throughout the entire piping 5, or they can be installed only in a part of it.

[0058] As described above, preferred embodiments of the present invention have been illustrated with reference to the accompanying drawings, but various additions, modifications, or deletions can be made without departing from the spirit of the invention. Therefore, such embodiments are also included within the scope of the present invention.

[0059] Label Explanation

[0060] 1: Insulated double-layer piping unit for liquefied gas; 3: Liquefied gas storage vessel; 5: Insulated double-layer piping; 5a: First straight pipe section; 5b: Second straight pipe section; 5c: Bent pipe section; 7: Base; 9: Restraint component; 25: Inner pipe; 27: Outer pipe; 31: Expansion allowance section; 33: Inner pipe spacer.

Claims

1. A double-layer insulated piping unit for liquefied petroleum gas (LPG), used for transferring LPG, wherein, This insulated double-layer piping unit for liquefied gas has the following features: A heat-insulated double-layer piping system, comprising an inner pipe through which the liquefied gas passes and an outer pipe covering the inner pipe with a vacuum layer, wherein the outer pipe has a telescopic allowable portion that allows for at least a change in length in the axial direction. A base having a counterpart facing the outer periphery of the insulated double-layer piping; A constraint component, fixed to the base, constrains the outer tube relative to the base so that it can displace at least along the axial direction. An inner tube spacer is provided on the outer circumferential surface of the inner tube to maintain the distance between the inner tube and the outer tube at a predetermined distance or more. Even in any state, whether at room temperature or low temperature, at least a portion of the inner tube spacer is configured to be located within the range of the axial width of the constraint member.

2. The insulated double-layer piping unit for liquefied gas according to claim 1, wherein, The insulated double-layer piping has a first straight pipe section and a second straight pipe section extending in a straight line, and a bent pipe section connected in such a way that the first straight pipe section is bent relative to the second straight pipe section. At least the first straight pipe section has the telescopic allowable portion. The second straight pipe section is provided with the constraint member, which constrains the second straight pipe section to be able to move laterally in the axial direction of the second straight pipe section and in the direction perpendicular to the opposition between the thermally insulated double-layer piping and the base.

3. The insulated double-layer piping unit for liquefied gas according to claim 1 or 2, wherein, The liquefied gas insulated double-layer piping unit also has a flat, low-friction component sandwiched between the insulated double-layer piping and the base. The low-friction component has a smaller coefficient of friction than the base at least on the surface that contacts the insulated double-layer piping.

4. The insulated double-layer piping unit for liquefied gas according to claim 1 or 2, wherein, The constraint member is configured such that a gap is formed between the constraint member and the outer tube, with the thermally insulated double-layer piping and the base facing opposite directions.

5. A liquefied gas storage vessel, comprising: hull; Storage tanks for storing liquefied gas located within the hull; and The insulated double-layer piping unit for liquefied gas according to any one of claims 1 to 4, one end of which is installed in the storage tank.

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