Piping unit for liquefied gas and method for assembling same

Abstract

A piping unit (1) for transferring liquefied gas comprises a first straight pipe (3A) and a second straight pipe (3B). The first straight pipe (3A) extends linearly, and includes a first inner pipe (5A) that allows the liquefied gas to pass therethrough and a first outer pipe (9A) that covers the first inner pipe (5A) with a vacuum layer (7) therebetween. The second straight pipe (3B) includes a second inner pipe (5B) that allows the liquefied gas to pass therethrough and a second outer pipe (9B) that covers the second inner pipe (5B) with a vacuum layer (7) therebetween. The second straight pipe (3B) extends linearly in a direction different from the extension direction of the first straight pipe (3A). The piping unit (1) further comprises: a connection bent pipe (11) that connects the first inner pipe (5A) and the second inner pipe (5B); and a cover pipe (15) that covers a connection portion (13) between the first inner pipe (5A) and the second inner pipe (5B), the connection portion (13) including at least the connection bent pipe (11).

Description

Liquefied gas piping unit and assembly method thereof Related Applications

[0001] This application claims priority from Japanese Patent Application No. 2023-203307, filed November 30, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a piping unit for liquefied gas and a method for assembling the same.

[0003] Conventionally, the use of a double-wall vacuum insulated pipe has been proposed as a pipe for transporting liquefied gases such as liquefied natural gas and liquefied hydrogen (see, for example, Patent Document 1). This double wall pipe has a structure in which an inner pipe is covered by an outer pipe with a vacuum insulation layer in between, so that high thermal insulation is obtained and the temperature rise of the low-temperature liquefied gas flowing inside the inner pipe can be effectively suppressed.

[0004] Liquefied gas piping is typically installed in large facilities, such as storage facilities with large tanks or liquefied gas carriers, and is often installed as a piping unit consisting of multiple pipes connected in different directions. Furthermore, double piping requires accessories for support and maintaining the gap between the inner and outer pipes. Furthermore, as mentioned above, double piping for liquefied gas requires a high level of vacuum between the inner and outer pipes, making installation of a piping unit consisting of double piping complicated. Therefore, conventionally, the double piping, including the accessories, is assembled in advance at a piping factory or the like, and then transported to the installation site, where installation can be performed with simple tasks such as connecting the double piping together. This improves the accuracy and efficiency of the assembly and installation of double piping units, which require advanced skills.

[0005] JP 2022-101284 A

[0006] However, in the past, double pipes were typically connected at installation sites in linear arrays. Therefore, double pipes with bends were pre-assembled as a unit and then transported to the installation site. As a result, a large space was required for temporary storage and transportation of the double pipes during the assembly process, resulting in high installation costs. Furthermore, the inclusion of bends in the pre-assembled pipe blocks made the manufacturing process more complicated, leading to increased manufacturing costs.

[0007] The object of the present disclosure is to solve the above-mentioned problems by reducing the manufacturing cost of a liquefied gas piping unit and reducing the installation cost by reducing the space required in the assembly process of the liquefied gas piping unit.

[0008] In order to achieve the above-mentioned object, the piping unit for liquefied gas according to the present disclosure is a piping unit for transporting liquefied gas, comprising: a first straight pipe extending in a straight line, which includes a first inner pipe through which the liquefied gas passes and a first outer pipe covering the first inner pipe via a vacuum layer; a second straight pipe extending in a straight line in a direction different from the extension direction of the first straight pipe, which includes a second inner pipe through which the liquefied gas passes and a second outer pipe covering the second inner pipe via a vacuum layer; a connecting curved pipe connecting the first inner pipe and the second inner pipe; and a cover pipe covering the connection portion between the first inner pipe and the second inner pipe, which includes at least the connecting curved pipe.

[0009] The method for assembling a piping unit for liquefied gas according to the present disclosure is a method for assembling the above-mentioned piping unit for liquefied gas, comprising: preparing the first straight pipe by 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; preparing the second straight pipe by combining the second inner pipe and the second outer pipe and evacuating the space between the second inner pipe and the second outer pipe to form the vacuum layer; connecting the first straight pipe and the second straight pipe via the connecting curved pipe by 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; and covering the connecting portion between the first inner pipe and the second inner pipe, including at least the connecting curved pipe, with the cover pipe.

[0010] According to the present disclosure, by improving the shape of the constituent blocks of the liquefied gas piping unit, it is possible to reduce manufacturing costs, and by improving the transportation efficiency of the liquefied gas piping unit, it is possible to reduce installation costs.

[0011] It should be noted that any combination of at least two elements disclosed in the claims and / or the specification and / or the drawings is included in the present disclosure, and in particular, any combination of two or more of the claims set forth in the claims is included in the present disclosure.

[0012] The present disclosure will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are merely for illustration and explanation purposes and should not be used to define the scope of the present disclosure. The scope of the present disclosure is defined by the accompanying claims. In the accompanying drawings, the same part numbers in multiple drawings indicate the same parts.

[0023] FIG. 1 is a plan view showing a schematic configuration of a liquefied gas piping unit according to an embodiment of the present disclosure.

[0024] FIG. 2 is a longitudinal sectional view showing, on an enlarged scale, the periphery of a connection portion of the liquefied gas piping unit of FIG. 1.

[0025] FIG. 3 is a longitudinal sectional view showing a modified example of the liquefied gas piping unit of FIG. 2, in which the cover tube has a different shape.

[0026] FIG. 4 is a perspective view showing a modified example of the liquefied gas piping unit of FIG. 2, in which the cover tube is divided in a different manner.

[0027] FIG. 5 is a longitudinal sectional view showing, on an enlarged scale, a connection portion between a straight pipe and a cover pipe of a liquefied gas piping unit according to an embodiment of the present disclosure.

[0028] FIG. 6 is a longitudinal sectional view showing a modified example of the liquefied gas piping unit of FIG. 5, in which the straight pipe and the cover pipe have different structures.

[0029] FIG. 7 is a longitudinal sectional view showing a modified example of the liquefied gas piping unit of FIG. 5, in which the closure portion has a different structure.

[0029] FIG. 8 is a flow chart showing a schematic configuration of a method for assembling a liquefied gas piping unit according to an embodiment of the present disclosure.

[0013] A preferred embodiment of the present disclosure will now be described with reference to the drawings. FIG. 1 shows a liquefied gas piping unit 1 according to one embodiment of the present disclosure. In the following description, this liquefied gas piping unit 1 will be simply referred to as the "piping unit 1." The piping unit 1 is used to transport 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 piping structure including an inner pipe 5 through which liquefied gas passes and an outer pipe 9 that covers the inner pipe 5 with a vacuum layer 7 interposed therebetween. The piping unit 1 further includes a connecting bent pipe 11 that connects the inner pipes 5 of the plurality of straight pipes 3 together, and a cover pipe 15 that covers a connection portion 13 between the inner pipes 5.

[0014] In this specification, one of the two straight pipes 3 connected by the connecting bent pipe 11 will be referred to as the "first straight pipe 3A," and the other straight pipe 3 will be referred to as the "second straight pipe 3B." Furthermore, the inner pipe 5 and outer pipe 9 of the first straight pipe 3A will be referred to as the "first inner pipe 5A" and the "first outer pipe 9A," respectively, and the inner pipe 5 and outer pipe 9 of the second straight pipe 3B will be referred to as the "second inner pipe 5B" and the "second outer pipe 9B," respectively. However, since the first straight pipe 3A and the second straight pipe 3B may have the same structure, when describing matters common to these straight pipes 3A and 3B, they will simply be referred to as the "straight pipe 3," the "inner pipe 5," and the "outer pipe 9."

[0015] 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 term "liquefied gas storage ship" refers to a ship that has the function of storing liquefied gas. In addition to liquefied gas carriers, liquefied gas storage ships also include, for example, liquefied gas fuel ships and bunkering ships that supply liquefied gas to other ships. However, the liquefied gas storage facility is not limited to ships as long as it has the structure and function to store liquefied gas, and may be, for example, an onshore liquefied gas storage facility or a plant that uses liquefied gas.

[0016] The liquefied gas transferred by the piping unit 1 is, 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.), or liquefied helium (LHe, approximately −270° C.). In this embodiment, liquefied hydrogen is transferred via the piping unit 1.

[0017] As shown in FIG. 2 , the second straight pipe 3B extends linearly in a different direction from the first straight pipe 3A. In the illustrated example, the first straight pipe 3A and the second straight pipe 3B are arranged so that the extending direction of the first straight pipe 3A and the extending direction of the second straight pipe 3B intersect at approximately a right angle on the same plane. Furthermore, in each straight pipe 3, the end of the inner pipe 5 protrudes from the outer pipe 9. The first inner pipe 5A of the first straight pipe 3A configured in this manner is connected to one end of a 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, thereby connecting the first inner pipe 5A and the second inner pipe 5B via the connecting curved pipe 11. Although not shown, each outer pipe 9 is provided with an exhaust port for evacuating the space between the outer pipe 9 and the inner pipe 5.

[0018] In this embodiment, the connecting curved pipe 11 has the same diameter at both ends as the inner pipes 5. The connecting curved pipe 11 is made of the same metal material as the inner pipes 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.

[0019] 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 of the connection portion consisting of the connecting bent pipe 11, the end of the first inner pipe 5A, and the end of the second inner pipe 5B connected via the connecting bent pipe 11, that is exposed from the first outer pipe 9A and the second outer pipe 9B. In this example, the "connection portion 13" refers to the portion consisting of the connecting bent pipe 11, the end of the first inner pipe 5A protruding from the first outer pipe 9A, and the end of the second inner pipe 5B protruding from the second outer pipe 9B. Furthermore, as shown in the example of FIG. 2 , the cover pipe 15 may extend beyond the "connection portion 13" and cover the ends of the first outer pipe 9A and the second outer pipe 9B. The extent to which the cover pipe 15 covers the first outer pipe 9A and the second outer pipe 9B can be determined appropriately depending on the length required to insulate the connection portion.

[0020] 2, the diameter of the cover tube 15 is larger than that of the outer tube 9, but the diameter of the cover tube 15 may be the same as that of the outer tube 9. For example, as shown as a modified example in FIG. 3, both end faces of the cover tube 15 may be connected to one end of the first outer tube 9A and one end of the second outer tube 9B, respectively. Alternatively, a step having a smaller diameter than the outer tube 9 may be provided at the end of the outer tube 9, and this step may be inserted into the cover tube 15.

[0021] The cover pipe 15 sealably covers the connection portion 13. Although not shown, the cover pipe 15 is provided with an exhaust port for evacuating the interior thereof, and when the installation of the piping unit 1 is complete, a vacuum layer 7 is formed inside the cover pipe 15.

[0022] In this embodiment, the cover tube 15 has a shape corresponding to the shape of the connecting curved pipe 11. That is, the cover tube 15 has a shape that is concave toward the connecting curved pipe 11 inside the connection section 13 that forms a corner shape that curves from the first straight pipe 3A through the connecting curved pipe 11 to the second straight pipe 3B, and a shape that is convex toward the opposite side of the connecting curved pipe 11 outside the corner shape. In the illustrated example, the cover tube 15 has a first cylindrical portion 15a that is larger in diameter than the first outer pipe 9A and concentric with the first outer pipe 9A, a second cylindrical portion 15b that is larger in diameter than the second outer pipe 9B and concentric with the second outer pipe 9B, and a curved pipe portion 15c that smoothly connects the first cylindrical portion 15a and the second cylindrical portion 15b. The shape of the cover tube 15 is not limited to this example, and may be, for example, a generally rectangular parallelepiped shape that is convex toward the opposite side of the connecting curved pipe 11 even inside the corner shape of the connection section 13. However, by forming the cover pipe 15 in a shape that corresponds to the shape of the connecting curved pipe 11, the installation space for the piping unit 1 can be reduced.

[0023] 2, in this embodiment, the cover tube 15 includes a plurality of segments 21. Specifically, in this example, the cover tube 15 is formed from a plurality of segments 21 (three segments in this example) lined up along the direction of extension from the first inner tube 5A to the second inner tube 5B. In other words, the cover tube 15 is formed from a plurality of segments 21 having shapes that are cut along a plane perpendicular to the direction of extension from the first inner tube 5A to the second inner tube 5B.

[0024] When the cover pipe 15 is formed from a plurality of segments 21, the manner of division is not limited to the above example. For example, as shown in Fig. 4, the cover pipe 15 may be formed from two segments 21 each having a shape obtained by cutting the first cylindrical portion 15a and the second cylindrical portion 15b in half along a plane along the extension direction. By forming the cover pipe 15 from the segments 21 in this way, as will be described later, the assembly work of the piping unit 1 at the installation site becomes easier. However, it is not essential that the cover pipe 15 be formed from the segments 21, and the cover pipe 15 may be formed as a single pipe body.

[0025] 1, in this embodiment, two straight pipes 3 arranged in a portion of the piping unit 1 where an L-shaped flow path is formed are connected by a connecting bent pipe 11 and a cover pipe 15 shown in FIG. 2, and the T-shaped flow path portion 23 is configured as a single double pipe. Accordingly, 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, the T-shaped flow path portion 23 in the piping unit 1 may also be configured by connecting three straight pipes 3 by a T-shaped bent pipe and a T-shaped cover pipe 15.

[0026] Furthermore, as shown in FIGS. 5 to 7 , the first straight pipe 3A and the cover pipe 15 may be flexible at the connection between them. Similarly, although not shown, the second straight pipe 3B and the cover pipe 15 may be flexible at the connection between them. Here, the connection between the straight pipe 3 and the cover pipe 15 refers to the location where these pipes interact with each other and the surrounding area, which is subject to the bending load caused by thermal contraction of the connecting bent pipe 11. For example, if the straight pipe 3 and the cover pipe 15 overlap, the connection portion includes the straight pipe 3 and the cover pipe 15 in the overlapping area as well as the closure portions 25, 27 of these pipes. Furthermore, for example, if the straight pipe 3 and the cover pipe 15 have the same pipe diameter and are connected ( FIG. 3 ), the connection portion refers to the connection point, including the closure portion of these pipes, and the surrounding area. The range of flexibility and the magnitude of allowable displacement at the connecting portion can be appropriately set according to the bending load that may occur due to thermal contraction of the connecting bent pipe 11 and its surroundings. Depending on the magnitude of the bending load that may occur due to thermal contraction, the stress may be able to be handled only by the inherent flexibility of the straight pipe 3, the cover pipe 15, and / or the closing portions 25, 27 themselves.

[0027] Flexibility of the connecting portion can be achieved, for example, by adopting the configurations shown in Figures 5 to 7. While the examples shown in Figures 5 to 7 employ a combination of configurations that provide flexibility to the connecting portion, this is not limited to these examples, and only one of these may be used depending on the bending load that occurs. Furthermore, the configuration shown only on the first straight pipe 3A side may also be provided on the second straight pipe 3B side.

[0028] As shown in Fig. 5, the cover pipe 15 may have a displacement-permitting portion 23 at the connection portion with the first straight pipe 3A. Although not shown, the cover pipe 15 may also have a displacement-permitting portion at the connection portion with the second straight pipe 3B. The displacement-permitting portion 23 is, for example, a bellows. If the cover pipe 15 is provided with a bellows, stress due to bending load can be alleviated.

[0029] Alternatively or additionally, the closing portion 25 of the first straight pipe 3A that closes the gap between the first outer pipe 9A and the first inner pipe 5A may be flexible, and the closing portion 27 of the cover pipe 15 that closes the gap between the cover pipe 15 and the first outer pipe 9A may be flexible. Similarly, the closing portion 25 of the second straight pipe 3B that closes the gap between the second outer pipe 9B and the second inner pipe 5B may be flexible, and the closing portion 27 of the cover pipe 15 that closes the gap between the cover pipe 15 and the second outer pipe 9B may be flexible. In this way, the closing portions 25, 27 of the straight pipe 3 and the cover pipe 15 are flexible, so that bending loads that may occur due to thermal contraction of the connecting curved pipe 11 and its surroundings can be absorbed, and stresses applied to the straight pipe 3 and the cover pipe 15 can be alleviated.

[0030] 6, even in a structure in which a step 31 having a smaller diameter than the outer pipe 9 is provided at the end of the outer pipe 9 and this step 31 is inserted into the cover pipe 15 for connection, the cover pipe 15 may have a displacement allowance portion 23 for imparting flexibility to the connection portion with the first straight pipe 3A in accordance with the generated bending load. This displacement allowance portion 23 may also be, for example, a bellows.

[0031] Alternatively or additionally, as shown in Fig. 7, the closing section 25 that closes the gap between the first outer pipe 9A and the first inner pipe 5A in the first straight pipe 3A may have a displacement-permitting structure with projections and recesses. Similarly, although not shown, the closing section that closes the gap between the second outer pipe 9B and the second inner pipe 5B in the second straight pipe 3B may have a displacement-permitting structure. By providing such a structure for the closing section at the end of the straight pipe, stress due to bending load can be alleviated and the heat transfer distance can be increased, thereby improving insulation performance.

[0032] Next, a method for assembling the piping unit 1 described above will be described.

[0033] 8, the assembly method according to this embodiment includes the steps of preparing a required number of straight pipes 3, for example, two straight pipes 3, connecting the first inner pipe 5A of the first straight pipe 3A to one end of a connecting curved pipe 11 and connecting the first straight pipe 3A to the second straight pipe 3B via the connecting curved pipe 11, and covering the connecting portion 13 between the first inner pipe 5A and the second inner pipe 5B with a cover pipe 15. In the following description, these steps will be referred to as the "straight pipe preparation step S1," the "straight pipe connecting step S2," and the "cover step S3," respectively.

[0034] In the straight pipe preparation step S1, the inner pipe 5 and the outer pipe 9 are assembled together, and then the space between the inner pipe 5 and the outer pipe 9 is evacuated to produce the straight pipe 3. When assembling the inner pipe 5 and the outer pipe 9, structural components such as a spacer to ensure a gap between the inner pipe 5 and the outer pipe 9, and an expansion / contraction member such as a bellows to absorb the difference in thermal contraction between the inner pipe 5 and the outer pipe 9 are used as needed. The evacuation is performed by connecting a vacuum pump to an exhaust port (not shown) provided in the outer pipe 9. A vacuum layer 7 is formed by the evacuation.

[0035] In the straight pipe connecting 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 connecting curved pipe 11 and each straight pipe 3 are connected by, for example, welding. However, the connecting curved pipe 11 and each straight pipe 3 may be connected 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 the "piping core assembly 27."

[0036] In the covering step S3 of this embodiment, after the connecting step, the piping core assembly 27 is inserted into each divided body 21 of the cover pipe 15, and then the divided bodies 21 are integrated by welding, thereby covering the connection portion 13 with the cover pipe 15. Thereafter, the internal space of the cover pipe 15 is evacuated. Note that the divided bodies 21 may be integrated by a method other than welding.

[0037] In addition, when the cover pipe 15 is formed as a single body rather than as a divided body 21, for example, the connection bent pipe 11 may be covered with the cover pipe 15, the connection bent pipe 11 may be fixed to the inside of the cover pipe 15, and then each straight pipe 3 may be connected to the connection bent pipe 11. In this case, the straight pipe connecting step S2 is performed after the covering step S3. Alternatively, the inner circumferential dimension of the cover pipe 15 may be set to a size that allows the connection portion 13 of the piping core assembly 27 to be inserted therethrough, and the connection portion 13 may be covered with the cover pipe 15 after the piping core assembly 27 is assembled.

[0038] In this 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 cover step S3 are performed is referred to as the "second location." Specifically, the first location is, for example, a factory where pipes are manufactured. The second location is, for example, a facility where the piping unit 1 is installed. Each straight pipe 3 is transported from the first location to the second location by transportation equipment such as a truck.

[0039] However, depending on the distance between the first location and the second location and the weight and number of straight pipes 3 to be transported, the workers may transport them. It is not essential that the straight pipe preparation step S1 and the subsequent straight pipe connection step S2 and cover step S3 be performed at different locations. As described above, the order of performing the straight pipe connection step S2 and cover step S3 is arbitrary.

[0040] A piping unit 1 for liquefied gas according to a first aspect of the present disclosure is a piping unit 1 for transporting liquefied gas, comprising: a first straight pipe 3A extending in a straight line, which includes a first inner pipe 5A through which the liquefied gas passes and a first outer pipe 9A covering the first inner pipe 5A with a vacuum layer 7 interposed therebetween; a second straight pipe 3B extending in a straight line in a direction different from the extension direction of the first straight pipe 3A, which includes a second inner pipe 5B through which the liquefied gas passes and a second outer pipe 9B covering the second inner pipe 5B with a vacuum layer 7 interposed therebetween; a connecting curved 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, which includes at least the connecting curved pipe 11.

[0041] According to this configuration, the piping unit 1 is constructed using straight piping without any bends as a unit, which makes it easier to manufacture the piping units, thereby reducing manufacturing costs. Furthermore, 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, thereby reducing installation costs. Furthermore, straight piping is easy to handle, which also improves the safety of installation work.

[0042] The liquefied gas piping unit 1 according to the second aspect of the present disclosure is the liquefied gas piping unit 1 according to the first aspect, wherein the cover pipe 15 has a shape corresponding to the shape of the connecting curved pipe 11. With this configuration, the installation space of the piping unit 1 can be reduced.

[0043] The liquefied gas piping unit 1 according to a third aspect of the present disclosure is the liquefied gas piping unit 1 according to the first or second aspect, wherein the cover pipe 15 includes a plurality of divided bodies 21. This configuration facilitates assembly of the piping unit 1 at the installation site.

[0044] The liquefied gas piping unit 1 according to a fourth aspect of the present disclosure is the liquefied gas piping unit 1 according to any one of the first to third aspects, wherein the first straight pipe 3A and the cover pipe 15 are flexible at a connection portion between the first straight pipe 3A and the cover pipe 15, and / or the second straight pipe 3B and the cover pipe 15 are flexible at a connection portion between the second straight pipe 3B and the cover pipe 15. With this configuration, bending loads that may occur due to thermal contraction of the connecting curved pipe 11 can be absorbed, and stresses applied to the straight pipe 3A and the cover pipe 15 can be alleviated.

[0045] A method for assembling a liquefied gas piping unit 1 according to a first aspect of the present disclosure is a method for assembling a liquefied gas piping unit 1 according to any one of the first to fourth aspects, and includes: 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 curved pipe 11 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; and covering the connection portion 13 between the first inner pipe 5A and the second inner pipe 5B, including at least the connecting curved pipe 11, with the cover pipe 15.

[0046] According to this configuration, the piping unit 1 is assembled using straight piping without any bends as a unit, which makes it easier to manufacture the piping units and reduces manufacturing costs. Furthermore, 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, thereby reducing installation costs. Furthermore, straight piping is easy to handle, which also improves the safety of installation work.

[0047] The method for assembling the liquefied gas piping unit 1 according to the second aspect of the present disclosure is the method for assembling the liquefied gas piping unit 1 according to the third aspect according to the first aspect, and includes connecting the first straight pipe 3A and the second straight pipe 3B via the connecting curved pipe 11, and then integrating the divided bodies 21 to cover the connection portion 13 with the cover pipe 15. According to this configuration, the assembly work can be performed efficiently by utilizing the cover pipe 15 formed of the divided bodies 21.

[0048] A method for assembling a liquefied gas piping unit 1 according to a third aspect of the present disclosure is the assembly method according to the first or second aspect, and includes transporting the first straight pipe 3A and the second straight pipe 3B, which are prepared at a first location, to a second location, 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 curved pipe portions, the space required for transporting the pipes can be reduced.

[0049] A fourth aspect of the present disclosure relates to a method for assembling a liquefied gas piping unit 1, and in the method for assembling the liquefied gas piping unit 1 according to the third aspect, the method further comprises transporting the liquefied gas piping unit 1 by a transport device. This configuration transports straight piping without any bends, thereby reducing the space required for the transport device and improving transportation efficiency. As a result, the installation cost of the piping unit 1 can be significantly reduced.

[0050] As described above, the preferred embodiments of the present disclosure have been described with reference to the drawings, but various additions, modifications, and deletions can be made without departing from the spirit of the present disclosure. Therefore, such additions, modifications, and deletions are also included in the scope of the present disclosure.

Claims

1. A piping unit for transporting liquefied gas, comprising: a first straight pipe extending in a straight line, the first straight pipe having a first inner pipe through which the liquefied gas passes and a first outer pipe covering the first inner pipe via a vacuum layer; a second straight pipe having 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 in a straight line in a direction different from the extension direction of the first straight pipe; a connecting curved pipe connecting the first inner pipe and the second inner pipe; and a cover pipe covering the connection portion of the first inner pipe and the second inner pipe, the connecting curved pipe being included in at least the connecting curved pipe.

2. A piping unit for liquefied gas according to claim 1, wherein the cover pipe has a shape corresponding to the shape of the connecting bent pipe.

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

4. A piping unit for liquefied gas as described in claim 1, wherein the first straight pipe and the cover pipe have flexibility at the connection between the first straight pipe and the cover pipe, and / or the second straight pipe and the cover pipe have flexibility at the connection between the second straight pipe and the cover pipe.

5. A method for assembling a piping unit for liquefied gas as described in claim 1, comprising: preparing the first straight pipe by 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; preparing the second straight pipe by combining the second inner pipe and the second outer pipe and evacuating the space between the second inner pipe and the second outer pipe to form the vacuum layer; connecting the first straight pipe and the second straight pipe via the connecting curved pipe by 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; and covering the connecting portion between the first inner pipe and the second inner pipe, including at least the connecting curved pipe, with the cover pipe.

6. A method for assembling a piping unit for liquefied gas as described in claim 5, which includes connecting the first straight pipe and the second straight pipe via the connecting bent pipe, and then covering the connection portion with the cover pipe by integrating the divided bodies in a divided state.

7. A method for assembling a piping unit for liquefied gas according to claim 5, comprising transporting the first straight pipe and the second straight pipe prepared at a first location to a second location, and at the second location, connecting the first straight pipe and the second straight pipe via the connecting bent pipe, and covering the connecting portion with the cover pipe.

8. A method for assembling a piping unit for liquefied gas according to claim 7, wherein the transporting is carried out by a transport device.

Images