Liquefied gas piping unit and assembling method therefor

Abstract

To reduce installation cost by reducing a space required in an assembly process of a liquefied gas piping unit.SOLUTION: A piping unit (1) for transferring liquefied gas comprises: a first straight pipe (3A) comprising a first inner pipe (5A) for passing the liquefied gas, and a first outer pipe (9A) covering the first inner pipe (5A) via a vacuum layer (7), and extending linearly; a second straight pipe (3B) comprising a second inner pipe (5B) for passing the liquefied gas, and a second outer pipe (9B) covering the second inner pipe (5B) via a vacuum layer (7), and extending linearly in a direction different from the extending direction of the first straight pipe (3A); a connection bent pipe (11) connecting the first inner pipe (5A) and the second inner pipe (5B); and a cover pipe (15) covering a connection portion (13) between the first inner pipe (5A) and the second inner pipe (5B), including at least the connection bent pipe (11).SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present disclosure relates to a piping unit for liquefied gas and a method for assembling the same.

Background Art

[0002] Conventionally, as piping for transporting liquefied gas such as liquefied natural gas and liquefied hydrogen, it has been proposed to use a double-structured vacuum-insulated pipe (see, for example, Patent Document 1). Since this double pipe has a structure in which the inner pipe is covered with the outer pipe via a vacuum insulation layer, high heat insulation performance can be obtained, and the temperature rise of the low-temperature liquefied gas flowing in the inner pipe can be effectively suppressed.

[0003] Generally, piping for liquefied gas is often installed in large facilities such as storage facilities equipped with large tanks and liquefied gas carriers, and is often installed as a piping unit to which a plurality of pipes extending in different directions are connected. Further, in the double pipe, accessory parts for support and spacing are provided between the inner pipe and the outer pipe, and as described above, in the double pipe for liquefied gas, it is necessary to maintain a high vacuum state between the inner pipe and the outer pipe. Therefore, the installation work of the piping unit composed of the double pipe becomes complicated. Therefore, conventionally, generally, after completing the assembly work of the double pipe including the accessory parts in a factory or the like of the piping, this is transported to the installation site, and at the installation site, it can be installed only by simple work such as connecting the double pipes to each other. Thereby, high-precision and high-efficiency assembly and installation work of the double pipe unit, which requires a high level of skill, can be achieved.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, conventionally, the connection of double pipes at the installation site was generally performed at locations arranged in a straight line. Therefore, pre-assembly was carried out using double pipes with a curved pipe section as a unit, and this was transported to the installation site. As a result, a large space was required for the primary storage and transportation of double pipes during the assembly process, resulting in high installation costs. In addition, since the pre-assembled pipe block included a curved pipe section, the manufacturing became complicated, leading to an increase in manufacturing costs.

[0006] An object of the present disclosure is to reduce the manufacturing cost of a piping unit for liquefied gas and to reduce the installation cost by reducing the space required during the assembly process of the piping unit for liquefied gas.

Means for Solving the Problems

[0007] To achieve the above object, a piping unit for liquefied gas according to the present disclosure is a piping unit for transferring liquefied gas, comprising a first inner pipe through which the liquefied gas passes, and a first outer pipe that covers the first inner pipe via a vacuum layer, and a first straight pipe that extends linearly, a second inner pipe through which the liquefied gas passes, and a second outer pipe that covers the second inner pipe via a vacuum layer, and a second straight pipe that extends linearly in a direction different from the extending direction of the first straight pipe, a connecting curved pipe that connects the first inner pipe and the second inner pipe, and a cover pipe that covers a connection portion between the first inner pipe and the second inner pipe and includes at least the connecting curved pipe.

[0008] A method for assembling a piping unit for liquefied gas according to the present disclosure is a method for assembling the above piping unit for liquefied gas, comprising combining the first inner pipe and the first outer pipe, and evacuating the space between the first inner pipe and the first outer pipe to form the vacuum layer to prepare the first straight pipe, Combining the second inner pipe and the second outer pipe, evacuating the space between the second inner pipe and the second outer pipe to form the vacuum layer, thereby preparing the second straight pipe; Connecting the first inner pipe of the first straight pipe to one end of the connecting curved pipe, and connecting the second inner pipe of the second straight pipe to the other end of the connecting curved pipe, thereby connecting the first straight pipe and the second straight pipe through the connecting curved pipe; Covering the connection portion between the first inner pipe and the second inner pipe, including at least the connecting curved pipe, with the cover pipe; including.

Advantages of the Invention

[0009] According to the present disclosure, by improving the shape of the constituent blocks of the liquefied gas piping unit, the manufacturing cost can be reduced, and by improving the transportation efficiency of the liquefied gas piping unit, the installation cost can be reduced.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0011] Hereinafter, preferred embodiments of the present disclosure will be described with reference to the drawings. FIG. 1 shows a piping unit 1 for liquefied gas according to an embodiment of the present disclosure. In the following description, this piping unit 1 for liquefied gas is simply referred to as "piping unit 1". The piping unit 1 is used for transporting liquefied gas. The piping unit 1 includes a plurality of straight pipes 3 extending linearly. As shown in FIG. 2, each straight pipe 3 has a double-pipe structure including an inner pipe 5 through which liquefied gas passes and an outer pipe 9 covering the inner pipe 5 via a vacuum layer 7. The piping unit 1 further includes a connecting curved pipe 11 connecting the inner pipes 5 of the plurality of straight pipes 3 and a cover pipe 15 covering the connection portion 13 between the inner pipes 5.

[0012] In this specification, one of the two straight pipes 3 connected by the connecting curved pipe 11 is referred to as "first straight pipe 3A", and the other straight pipe 3 is referred to as "second straight pipe 3B". Also, the inner pipe 5 and the outer pipe 9 of the first straight pipe 3A are referred to as "first inner pipe 5A" and "first outer pipe 9A", respectively, and the inner pipe 5 and the outer pipe 9 of the second straight pipe 3B are referred to as "second inner pipe 5B" and "second outer pipe 9B", respectively. However, since the first straight pipe 3A and the second straight pipe 3B may have the same structure, when explaining matters common to these straight pipes 3A and 3B, they are simply referred to as "straight pipe 3", "inner pipe 5", and "outer pipe 9".

[0013] The piping unit 1 is used in liquefied gas storage facilities such as liquefied gas storage ships and onshore liquefied gas storage bases. In this specification, the "liquefied gas storage ship" refers to a ship having a function of storing liquefied gas. In addition to liquefied gas carriers, for example, liquefied gas fuel ships, bunkering ships that supply liquefied gas to other ships, etc. are included in the liquefied gas storage ships. However, the liquefied gas storage facility is not limited to a ship as long as it has a structure and function of storing liquefied gas, and may be, for example, an onshore liquefied gas storage facility or a plant that uses liquefied gas.

[0014] The liquefied gas transferred by the piping unit 1 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 (LH 2 , about -250°C), liquefied helium (LHe, about -270°C). In this embodiment, liquefied hydrogen is transferred through the piping unit 1.

[0015] As shown in FIG. 2, the second straight pipe 3B extends linearly in a direction different from that of the first straight pipe 3A. In the illustrated example, the first straight pipe 3A and the second straight pipe 3B are arranged such that the extending direction of the first straight pipe 3A and the extending direction of the second straight pipe 3B intersect at substantially a right angle on the same plane. Further, at each straight pipe 3, the end of the inner pipe 5 protrudes from the outer pipe 9. By connecting the first inner pipe 5A of the first straight pipe 3A to one end of the connecting curved pipe 11 and connecting the second inner pipe 5B of the second straight pipe 3B to the other end of the connecting curved pipe 11, the first inner pipe 5A and the second inner pipe 5B are connected via the connecting curved pipe 11. Although not shown in the figure, each outer pipe 9 is provided with an exhaust port for evacuating the space between the inner pipe 5.

[0016] In this embodiment, the connecting curved pipe 11 has the same diameter as each inner pipe 5 at both ends. Further, the connecting curved pipe 11 is formed of the same metal material as the inner pipe 5. In the illustrated example, the connecting curved pipe 11 is formed in a curved shape that smoothly deflects from the extending direction of the first straight pipe 3A to the extending direction of the second straight pipe 3B. However, the shape of the connecting curved pipe 11 is not limited to a curved shape.

[0017] The cover pipe 15 covers the connection portion 13 between the first inner pipe 5A and the second inner pipe 5B. Specifically, the "connection portion 13" covered by the cover pipe 15 refers to the portion that is exposed from the first outer pipe 9A and the second outer pipe 9B among the connection curved pipe 11, the end portion of the first inner pipe 5A connected via the connection curved pipe 11, and the end portion of the second inner pipe 5B. In this example, the portion consisting of the connection curved pipe 11, the end portion protruding from the first outer pipe 9A in the first inner pipe 5A, and the end portion protruding from the second outer pipe 9B in the second inner pipe 5B becomes the "connection portion 13". Also, as shown in the example of FIG. 2, the cover pipe 15 may cover up to the end portions of the first outer pipe 9A and the second outer pipe 9B beyond the range of the "connection portion 13". The range in which the cover pipe 15 covers the first outer pipe 9A and the second outer pipe 9B can be appropriately determined according to the length required for heat insulation of the connection portion.

[0018] Also, in the example of FIG. 2, the diameter of the cover pipe 15 is larger than the diameter of the outer pipe 9, but the diameter of the cover pipe 15 may be the same as the diameter of the outer pipe 9. For example, as shown as a modified example in FIG. 3, the end faces at both ends of the cover pipe 15 may be respectively connected to the end faces of one end of the first outer pipe 9A and one end of the second outer pipe 9B. Alternatively, a stepped portion having a smaller diameter than the outer pipe 9 may be provided at the end portion of the outer pipe 9, and this stepped portion may be inserted into the cover pipe 15.

[0019] The cover pipe 15 covers the connection portion 13 in a sealable state. Also, although not shown in the drawing, the cover pipe 15 is provided with an exhaust port for evacuating its interior, and a vacuum layer 7 is formed inside the cover pipe 15 in a state where the installation of the piping unit 1 is completed.

[0020] In this embodiment, the cover pipe 15 has a shape corresponding to the shape of the connecting bent pipe 11. That is, the cover pipe 15 is recessed on the side of the connecting bent pipe 11 inside the connecting portion 13 that forms a corner shape that deflects from the first straight pipe 3A through the connecting bent pipe 11 to the second straight pipe 3B, and has a shape that protrudes to the side opposite to the connecting bent pipe 11 outside the corner shape. In the illustrated example, the cover pipe 15 has a first cylindrical portion 15a having a larger diameter than the first outer pipe 9A and concentric with the first outer pipe 9A, a second cylindrical portion 15b having a larger diameter than the second outer pipe 9B and concentric with the second outer pipe 9B, and a curved pipe portion 15c having a shape that smoothly connects the first cylindrical portion 15a and the second cylindrical portion 15b. The shape of the cover pipe 15 is not limited to this example. For example, it may have a substantially rectangular parallelepiped shape as a whole that protrudes to the side opposite to the connecting bent pipe 11 even inside the corner shape of the connecting portion 13. However, by shaping the cover pipe 15 to correspond to the shape of the connecting bent pipe 11, the installation space of the piping unit 1 can be reduced.

[0021] As shown in FIG. 2, in this embodiment, the cover pipe 15 includes a plurality of divided bodies 21. Specifically, in this example, the cover pipe 15 is formed from a plurality, in this case three, of divided bodies 21 arranged along the extending direction from the first inner pipe 5A to the second inner pipe 5B. In other words, the cover pipe 15 is formed from a plurality of divided bodies 21 having a shape cut by a plane orthogonal to the extending direction from the first inner pipe 5A to the second inner pipe 5B.

[0022] When the cover pipe 15 is formed from a plurality of divided bodies 21, the dividing mode is not limited to the above example. For example, as shown in FIG. 4, the cover pipe 15 may be formed from two divided bodies 21 having a shape in which the first cylindrical portion 15a and the second cylindrical portion 15b are cut in half by a plane along the extending direction. Thus, by forming the cover pipe 15 from the divided bodies 21, as will be described later, the assembly work of the piping unit 1 at the installation site becomes easier. However, it is not essential to form the cover pipe 15 from the divided bodies 21, and it may be formed as a single pipe body.

[0023] As shown in FIG. 1, in this embodiment, two straight pipes 3 arranged at a portion where an L-shaped flow path is formed in the piping unit 1 are connected by a connecting curved pipe 11 and a cover pipe 15 shown in FIG. 2, and the T-shaped flow path portion 23 is composed of a single double pipe. Along with this, one end of the double pipe of the T-shaped flow path portion 23 is connected to the straight pipe 3 via a straight cover pipe 25. However, regarding the T-shaped flow path portion 23 in the piping unit 1, three straight pipes 3 may also be connected by a T-shaped curved pipe and a T-shaped cover pipe 15.

[0024] Furthermore, as shown in FIGS. 5 to 7, the first straight pipe 3A and the cover pipe 15 may have flexibility at the connecting portion between the first straight pipe 3A and the cover pipe 15. Similarly, although not shown, the second straight pipe 3B and the cover pipe 15 may have flexibility at the connecting portion between the second straight pipe 3B and the cover pipe 15. Here, the connecting portion between the straight pipe 3 and the cover pipe 15 refers to the location where these pipes act on each other and its surroundings, and is a portion that can be affected by the bending load due to the heat shrinkage of the connecting curved pipe 11. For example, in the case where the straight pipe 3 and the cover pipe 15 overlap, the connecting portion includes the straight pipe 3 and the cover pipe 15 in the overlapping range and the closing portions 25, 27 of these pipes. Also, for example, when the straight pipe 3 and the cover pipe 15 are connected with the same pipe diameter (FIG. 3), the connecting portion is the connecting location including the closing portions of these pipes and its surroundings. The range having flexibility and the magnitude of the allowable displacement at the connecting portion can be appropriately set according to the bending load that can be generated by the heat shrinkage of the connecting curved pipe 11 and its surroundings. Depending on the magnitude of the bending load that can be generated by the heat shrinkage, the stress can be accommodated only by the inherent flexibility of the straight pipe 3, the cover pipe 15, and / or the closing portions 25, 27 themselves.

[0025] The flexibility of the connecting portion can be realized, for example, by adopting the modes shown in FIGS. 5 to 7. In the examples of FIGS. 5 to 7, a configuration that gives flexibility to the connecting portion is combined and adopted, but it is not limited to these examples, and depending on the generated bending load, only any one of them may be used. Also, the configuration shown only on the first straight pipe 3A side may be provided on the second straight pipe 3B side as well.

[0026] As shown in FIG. 5, the cover pipe 15 may have a displacement allowance portion 23 at the connecting portion with the first straight pipe 3A. Although not shown, the cover pipe 15 may also have a displacement allowance portion at the connecting portion with the second straight pipe 3B. The displacement allowance portion 23 is, for example, a bellows. When a bellows is provided on the cover pipe 15, the stress due to the bending load can be relieved.

[0027] Alternatively or additionally, in the first straight pipe 3A, the closing portion 25 that closes between the first outer pipe 9A and the first inner pipe 5A may have flexibility, and in the cover pipe 15, the closing portion 27 that closes between the cover pipe 15 and the first outer pipe 9A may have flexibility. Similarly, in the second straight pipe 3B, the closing portion 25 that closes between the second outer pipe 9B and the second inner pipe 5B may have flexibility, and in the cover pipe 15, the closing portion 27 that closes between the cover pipe 15 and the second outer pipe 9B may have flexibility. In this way, by the closing portions 25 and 27 of the straight pipe 3 and the cover pipe 15 having flexibility, the bending load that may be generated by the thermal contraction of the connecting bent pipe 11 and its surroundings can be absorbed, and the stress applied to the straight pipe 3 and the cover pipe 15 can be relieved.

[0028] Also, as shown in FIG. 6, even when a structure is provided in which a stepped portion 31 having a smaller diameter than the outer pipe 9 is provided at the end of the outer pipe 9 and this stepped portion 31 is inserted into and connected to the cover pipe 15, the cover pipe 15 may have a displacement allowance portion 23 for imparting flexibility to the connecting portion with the first straight pipe 3A according to the generated bending load. This displacement allowance portion 23 is also, for example, a bellows.

[0029] Alternatively or additionally, as shown in FIG. 7, the closing portion 25 that closes between the first outer pipe 9A and the first inner pipe 5A in the first straight pipe 3A may have a displacement allowance structure having irregularities. Similarly, although not shown, the closing portion that closes between the second outer pipe 9B and the second inner pipe 5B in the second straight pipe 3B may have a displacement allowance structure. By making the closing portion at the end of the straight pipe have such a structure, the stress due to the bending load can be relieved, and the heat insulation performance can also be improved by increasing the heat transfer distance.

[0030] Next, a method for assembling the pipe unit 1 described above will be described.

[0031] As shown in FIG. 8, the assembly method according to the present embodiment includes a step of preparing a necessary number, for example, two straight pipes 3, a step of connecting the first inner pipe 5A of the first straight pipe 3A to one end of the connecting curved pipe 11 and connecting the first straight pipe 3A and the second straight pipe 3B via the connecting curved pipe 11, and a step of covering the connection portion 13 between the first inner pipe 5A and the second inner pipe 5B with the cover pipe 15. In the following description, these steps will be referred to as "straight pipe preparation step S1", "straight pipe connection step S2", and "covering step S3" in order.

[0032] In the straight pipe preparation step S1, after combining the inner pipe 5 and the outer pipe 9, the space between the inner pipe 5 and the outer pipe 9 is evacuated to manufacture the straight pipe 3. When combining the inner pipe 5 and the outer pipe 9, structural parts such as spacers for ensuring the distance between the inner pipe 5 and the outer pipe 9 and expansion and contraction allowance members such as bellows for absorbing the thermal shrinkage difference between the inner pipe 5 and the outer pipe 9 are appropriately used as necessary. The evacuation is performed by connecting a vacuum pump to an exhaust port (not shown) provided in the outer pipe 9. The vacuum layer 7 is formed by the evacuation.

[0033] In the straight pipe connection step S2, the first inner pipe 5A of the first straight pipe 3A is connected to one end of the connecting curved pipe 11, and the second inner pipe 5B of the second straight pipe 3B is connected to the other end of the connecting curved pipe 11. The connection between the connecting curved pipe 11 and each straight pipe 3 is performed, for example, by welding. However, the connection between the connecting curved pipe 11 and each straight pipe 3 may be performed by other methods. In the following description, the connected first straight pipe 3A, connecting curved pipe 11, and second straight pipe 3B will be referred to as "pipe core assembly 27".

[0034] In the covering step S3, in the present embodiment, after the above connection step, the pipe core assembly 27 is inserted through each divided body 21 of the cover pipe 15, and then the divided bodies 21 are integrated by welding to cover the connection portion 13 with the cover pipe 15. Then, the internal space of the cover pipe 15 is evacuated. Note that the integration of the divided bodies 21 may be performed by a method other than welding.

[0035] In addition, when the cover pipe 15 is formed as a single unit instead of a divided body 21, for example, after fixing the connecting curved pipe 11 inside the cover pipe 15 in a state where the connecting curved pipe 11 is covered with the cover pipe 15, each straight pipe 3 may be connected to the connecting curved pipe 11. In this case, the straight pipe connection step S2 is performed after the cover step S3. Alternatively, after assembling the piping core assembly 27 with the inner peripheral dimension of the cover pipe 15 being sized to allow the connection portion 13 of the piping core assembly 27 to pass through, the connection portion 13 may be covered with the cover pipe 15.

[0036] Also, in the present embodiment, the straight pipe preparation step S1 and the subsequent straight pipe connection step S2 and cover step S3 are performed at different locations. In this specification, the location where the straight pipe preparation step S1 is performed is referred to as the "first location", and the location where the straight pipe connection step S2 and the cover step S3 are performed is referred to as the "second location". Specifically, the first location is, for example, a factory where the piping is manufactured. The second location is, for example, a facility where the piping unit 1 is installed. The transportation of each straight pipe 3 from the first location to the second location is performed by a transportation device such as a truck vehicle.

[0037] However, depending on the distance between the first location and the second location, the weight and number of the straight pipes 3 to be transported, the operator may transport them. Also, it is not essential to perform the straight pipe preparation step S1 and the subsequent straight pipe connection step S2 and cover step S3 at different locations. Also, as described above, the order of performing the straight pipe connection step S2 and the cover step S3 is arbitrary.

[0038] The liquefied gas piping unit 1 according to the first aspect of the present disclosure is a piping unit 1 for transferring liquefied gas, comprising a first inner pipe 5A through which the liquefied gas passes, and a first outer pipe 9A that covers the first inner pipe 5A via a vacuum layer 7, and a first straight pipe 3A that extends linearly, comprising a second inner pipe 5B through which the liquefied gas passes, and a second outer pipe 9B that covers the second inner pipe 5B via a vacuum layer 7, and a second straight pipe 3B that extends linearly in a direction different from the extending direction of the first straight pipe 3A, A connecting bent pipe 11 that connects the first inner pipe 5A and the second inner pipe 5B, A cover pipe 15 that covers a connection portion 13 between the first inner pipe 5A and the second inner pipe 5B, including at least the connecting bent pipe 11.

[0039] According to this configuration, the piping unit 1 is configured with straight pipes without a bent pipe portion as a unit, so that the pipes of the constituent unit can be manufactured more easily, and the manufacturing cost can be reduced. In addition, the space required for temporary storage and transportation in the factory and at the installation site during the assembly process of the liquefied gas piping unit 1 is reduced, and the installation cost can also be reduced. Furthermore, the straight pipe is easy to handle, which also leads to an improvement in the safety of the installation work.

[0040] In the liquefied gas piping unit 1 according to the second aspect of the present disclosure, in the liquefied gas piping unit 1 according to the first aspect, the cover pipe 15 has a shape corresponding to the shape of the connecting bent pipe 11. According to this configuration, the installation space of the piping unit 1 can be reduced.

[0041] In the liquefied gas piping unit 1 according to the third aspect of the present disclosure, in the liquefied gas piping unit 1 according to the first or second aspect, the cover pipe 15 includes a plurality of divided bodies 21. According to this configuration, the assembly work of the piping unit 1 at the installation site becomes easy.

[0042] In the liquefied gas piping unit 1 according to the fourth aspect of the present disclosure, in the liquefied gas piping unit 1 according to any one of the first to third aspects, the first straight pipe 3A and the cover pipe 15 have flexibility at the connecting portion between the first straight pipe 3A and the cover pipe 15, and / or the second straight pipe 3B and the cover pipe 15 have flexibility at the connecting portion between the second straight pipe 3B and the cover pipe 15. According to this configuration, the bending load that may be generated due to the thermal contraction of the connecting bent pipe 11 can be absorbed, and the stress applied to the straight pipe 3 and the cover pipe 15 can be relaxed.

[0043] The method for assembling the liquefied gas piping unit 1 according to the first aspect of the present disclosure is a method for assembling the liquefied gas piping unit 1 according to any one of the first to fourth aspects, and preparing the first straight pipe 3A by combining the first inner pipe 5A and the first outer pipe 9A and evacuating the space between the inner pipe 5 and the outer pipe 9 to form the vacuum layer 7; preparing the second straight pipe 3B by combining the second inner pipe 5B and the second outer pipe 9B; connecting the first straight pipe 3A and the second straight pipe 3B via the connecting bent pipe 11 by connecting the first inner pipe 5A of the first straight pipe 3A to one end of the connecting bent pipe 11 and connecting the second inner pipe 5B of the second straight pipe 3B to the other end of the connecting bent pipe 11; covering a connection portion 13 between the first inner pipe 5A and the second inner pipe 5B, including at least the connecting bent pipe 11, with the cover pipe 15.

[0044] According to this configuration, since the piping unit 1 is assembled with straight pipes having no bent pipe portions as units, the constituent unit pipes can be manufactured more easily, and the manufacturing cost can be reduced. In addition, the space required for temporary storage and transportation in the factory and at the installation site during the assembly process of the liquefied gas piping unit 1 is reduced, and the installation cost can also be reduced. Furthermore, the straight pipe is easy to handle, which also leads to an improvement in the safety of the installation work.

[0045] The method for assembling the liquefied gas piping unit 1 according to the second aspect of the present disclosure is the assembling method according to the first aspect for assembling the liquefied gas piping unit 1 according to the third aspect, and includes covering the connection portion 13 with the cover pipe 15 by integrating the divided body 21 in a divided state after connecting the first straight pipe 3A and the second straight pipe 3B via the connecting bent pipe 11. According to this configuration, the assembly work can be efficiently performed using the cover pipe 15 composed of the divided body 21.

[0046] The method for assembling the liquefied gas piping unit 1 according to the third aspect of the present disclosure includes transporting the first straight pipe 3A and the second straight pipe 3B prepared at the first location to the second location in the assembling method according to the first or second aspect, and at the second location, connecting the first straight pipe 3A and the second straight pipe 3B via the connecting curved pipe 11, and covering the connecting portion 13 with the cover pipe 15. According to this configuration, by using straight pipes without a curved pipe portion, the space required for transporting the pipes can be reduced.

[0047] The method for assembling the liquefied gas piping unit 1 according to the fourth aspect of the present disclosure includes performing the transportation by a transportation device in the assembling method according to the third aspect. According to this configuration, by transporting straight pipes without a curved pipe portion, the space required for the transportation device is reduced, so the transportation efficiency is improved. As a result, the installation cost of the piping unit 1 can be significantly reduced.

[0048] As described above, the preferred embodiments of the present disclosure have been described with reference to the drawings, but various additions, changes, or deletions are possible without departing from the spirit of the present disclosure. Therefore, such things are also included in the scope of the present disclosure.

Explanation of Reference Numerals

[0049] 1 Liquefied gas piping unit 3 Straight pipe 3A First straight pipe 3B Second straight pipe 5 Inner pipe 5A First inner pipe 5B Second inner pipe 7 Vacuum layer 9 Outer pipe 9A First outer pipe 9B Second outer pipe 11 Connecting curved pipe 13 Connecting portion 15 Cover pipe 21 Divided body of the cover pipe 23 Displacement allowance portion 25 Closing portion of the straight pipe Closing part of the cover tube Step part

Claims

1. A piping unit for transferring liquefied gas, comprising: a first inner pipe through which the liquefied gas passes, and a first outer pipe covering the first inner pipe via a vacuum layer, the first straight pipe extending linearly; a second inner pipe through which the liquefied gas passes, and a second outer pipe covering the second inner pipe via a vacuum layer, the second straight pipe extending linearly in a direction different from the extending direction of the first straight pipe; a connecting curved pipe connecting the first inner pipe and the second inner pipe; a cover pipe covering a connection portion between the first inner pipe and the second inner pipe, including at least the connecting curved pipe; A liquefied gas piping unit comprising the above.

2. In the liquefied gas piping unit according to Claim 1, the cover pipe has a shape corresponding to the shape of the connecting curved pipe. A liquefied gas piping unit.

3. In the liquefied gas piping unit according to Claim 1, the cover pipe includes a plurality of divided bodies. A liquefied gas piping unit.

4. In the liquefied gas piping unit according to Claim 1, the first straight pipe and the cover pipe have flexibility at a connection portion between the first straight pipe and the cover pipe, and / or the second straight pipe and the cover pipe have flexibility at a connection portion between the second straight pipe and the cover pipe. A liquefied gas piping unit.

5. A method for assembling the liquefied gas piping unit according to Claim 1, comprising: combining the first inner pipe and the first outer pipe, and evacuating a space between the first inner pipe and the first outer pipe to form the vacuum layer to prepare the first straight pipe; combining the second inner pipe and the second outer pipe, and evacuating a space between the second inner pipe and the second outer pipe to form the vacuum layer to prepare the second straight pipe; connecting the first inner pipe of the first straight pipe to one end of the connecting curved pipe, and connecting the second inner pipe of the second straight pipe to the other end of the connecting curved pipe to connect the first straight pipe and the second straight pipe via the connecting curved pipe; covering a connection portion between the first inner pipe and the second inner pipe, including at least the connecting curved pipe, with the cover pipe; A method for assembling a liquefied gas piping unit, including the above steps.

6. The assembling method according to Claim 5 for assembling the liquefied gas piping unit according to Claim 3, After connecting the first straight pipe and the second straight pipe through the connecting curved pipe, covering the connection portion with the cover pipe by integrating the divided body in a divided state, A method for assembling a piping unit for liquefied gas.

7. The assembling method according to claim 5, including transporting the first straight pipe and the second straight pipe prepared at a first location to a second location, at the second location, connecting the first straight pipe and the second straight pipe through the connecting curved pipe, and covering the connection portion with the cover pipe, A method for assembling a piping unit for liquefied gas.

8. The assembling method according to claim 7, wherein the transporting is performed by a transportation device, A method for assembling a piping unit for liquefied gas.

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