Pipe unit for liquefied gas and method for assembling the same

Abstract

A pipe unit (1) for transporting liquefied gas has a first straight pipe (3A) and a second straight pipe (3B). The first straight pipe (3A) extends in a straight line, has a first inner pipe (5A) through which the liquefied gas passes, and a first outer pipe (9A) that covers the first inner pipe (5A) with a vacuum layer (7) interposed. The second straight pipe (3B) extends in a straight line in a direction different from the direction in which the first straight pipe (3A) extends, has a second inner pipe (5B) through which the liquefied gas passes, and a second outer pipe (9B) that covers the second inner pipe (5B) with a vacuum layer (7) interposed. The pipe unit (1) further has a connecting elbow (11) that connects the first inner pipe (5A) and the second inner pipe (5B), and a cover pipe (15) that covers a connecting portion (13) of the first inner pipe (5A) and the second inner pipe (5B) at least including the connecting elbow (11).

Description

[0001] Related applications

[0002] This application claims priority to Japanese Patent Application No. 2023-203307, filed on November 30, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to piping units for liquefied petroleum gas and methods for assembling them. Background Technology

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

[0005] Typically, liquefied petroleum gas (LPG) piping is mostly installed in large facilities such as storage tanks and LPG transport ships, and is often configured as piping units connecting multiple pipes extending in different directions. Furthermore, double-layer piping includes auxiliary components for support and spacing between the inner and outer pipes. As mentioned above, a high vacuum is required between the inner and outer pipes in double-layer LPG piping, making the installation of piping units with double-layer piping complex. Therefore, conventionally, double-layer piping, including auxiliary components, is usually assembled in advance at the piping factory and then transported to the installation site, where it can be installed simply by connecting the double-layer pipes together. This allows for high precision and efficiency in the assembly and installation of double-layer piping units, which require highly skilled personnel.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2022-101284 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] However, in the past, the connection of double-layer piping at the installation site was usually carried out at sections arranged in a straight line. Therefore, double-layer piping units with curved sections were pre-assembled and transported to the installation site. As a result, a large space was required for the storage and transportation of the double-layer piping during assembly, leading to higher installation costs. Furthermore, the inclusion of curved sections in the pre-assembled piping modules increased manufacturing complexity and costs.

[0011] The purpose of this disclosure is to solve the above-mentioned problems, reduce the manufacturing cost of liquefied gas piping units, and reduce the space required during the assembly of liquefied gas piping units, thereby reducing installation costs.

[0012] Methods for solving problems

[0013] To achieve the above objectives, the liquefied gas piping unit disclosed herein is used for transporting liquefied gas, wherein the liquefied gas piping unit comprises: a first straight pipe extending in a straight line, having a first inner pipe through which the liquefied gas passes and a first outer pipe covering the first inner pipe with 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, having a second inner pipe through which the liquefied gas passes and a second outer pipe covering the second inner pipe with a vacuum layer; a connecting curved pipe connecting the first inner pipe and the second inner pipe; and a cover pipe covering at least the connecting portion including the connecting curved pipe, the connection portion of the first inner pipe and the second inner pipe.

[0014] The present disclosure discloses an assembly method for a liquefied petroleum gas (LPG) piping unit, comprising the following steps: 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 a vacuum layer, thereby preparing the first straight pipe; 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 a 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 via the connecting curved pipe; and covering at least the connecting portion of the first inner pipe and the second inner pipe, including the connecting curved pipe, with the cover pipe.

[0015] According to this disclosure, by improving the shape of the constituent modules of the liquefied gas piping unit, the manufacturing cost can be reduced, and by improving the conveying efficiency of the liquefied gas piping unit, the installation cost can be reduced.

[0016] Furthermore, any combination of at least two constituent elements disclosed in the claims and / or description and / or drawings is included in this disclosure. In particular, any combination of two or more claims recited in the claims is included in this disclosure. Attached Figure Description

[0017] This 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 for illustration and description only and should not be used to define the scope of this disclosure. The scope of this disclosure is determined by the appended claims. In the drawings, the same part numbers in the plurality of drawings denote the same parts.

[0018] Figure 1 This is a top view showing a schematic structure of a liquefied gas piping unit according to one embodiment of the present disclosure.

[0019] Figure 2 It is shown in magnification Figure 1 A longitudinal sectional view of the periphery of the connection portion of the liquefied gas piping unit.

[0020] Figure 3 It is shown in Figure 2 A longitudinal sectional view of a variant example of a liquefied gas piping unit with a different hood shape.

[0021] Figure 4 It is shown in Figure 2 A three-dimensional diagram of a variant of a liquefied gas piping unit with a different method of pipe segmentation.

[0022] Figure 5 This is an enlarged longitudinal sectional view showing the connection between the straight pipe and the cover pipe of a liquefied gas piping unit according to an embodiment of the present disclosure.

[0023] Figure 6 It is shown in Figure 5 A longitudinal sectional view of a variant example of the different construction of straight pipes and shrouds in a liquefied gas piping unit.

[0024] Figure 7 It is shown in Figure 5 A longitudinal sectional view of a variant of the construction of the sealing section in a liquefied gas piping unit, with a different structure.

[0025] Figure 8 This is a flowchart illustrating the general structure of an assembly method for a liquefied gas piping unit according to one embodiment of the present disclosure. Detailed Implementation

[0026] Hereinafter, preferred embodiments of the present disclosure will be described with reference to the accompanying drawings. Figure 1 A liquefied petroleum gas (LPG) piping unit 1 according to one embodiment of this disclosure is shown. In the following description, this LPG piping unit 1 will be simply referred to as "piping unit 1". Piping unit 1 is used for the transportation of LPG. Piping unit 1 has a plurality of straight pipes 3 extending in a straight line. For example... Figure 2As shown, each straight pipe 3 has a double-layer piping structure, which has an inner pipe 5 through which liquefied gas passes and an outer pipe 9 covering the inner pipe 5 through a vacuum layer 7. The piping unit 1 also has a connecting curved pipe 11 that connects the inner pipes 5 of the multiple straight pipes 3 to each other and a cover pipe 15 that covers the connecting portion 13 of the inner pipes 5 to each other.

[0027] 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". Furthermore, the inner pipe 5 and 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 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 can have the same structure, when describing the common aspects of these straight pipes 3A and 3B, they are simply referred to as "straight pipe 3", "inner pipe 5", and "outer pipe 9".

[0028] Piping unit 1 is used, for example, in liquefied gas storage facilities such as liquefied gas storage ships or land-based liquefied gas storage bases. In this specification, "liquefied gas storage ship" refers to a vessel with the function of storing liquefied gas. Besides liquefied gas transport ships, liquefied gas storage ships also include, for example, liquefied gas fuel ships and fuel ships that supply liquefied gas to other ships. However, liquefied gas storage equipment is not limited to ships; it can be any equipment with the structure and function of storing liquefied gas. For example, it can also be a land-based liquefied gas storage facility or an equipment that utilizes liquefied gas.

[0029] The liquefied gas transported by 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 transported via piping unit 1.

[0030] like Figure 2 As shown, the second straight pipe 3B extends in a straight line 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 configured such that the extending direction of the first straight pipe 3A intersects the extending direction of the second straight pipe 3B approximately at right angles 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 way, 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, thereby connecting the first inner pipe 5A and the second inner pipe 5B 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 it and the inner pipe 5.

[0031] In this embodiment, the connecting curved tube 11 has the same diameter at both ends as each inner tube 5. Furthermore, the connecting curved tube 11 is formed of the same metal material as the inner tube 5. In the illustrated example, the connecting curved tube 11 is formed as a bend that smoothly deflects from the extension direction of the first straight tube 3A to the extension direction of the second straight tube 3B. However, the shape of the connecting curved tube 11 is not limited to a curved shape.

[0032] The cover tube 15 covers the connection portion 13 between the first inner tube 5A and the second inner tube 5B. Specifically, the "connection portion 13" covered by the cover tube 15 refers to the portion of the part formed by the connecting curved tube 11, the end of the first inner tube 5A connected via the connecting curved tube 11, and the end of the second inner tube 5B that protrudes from the first outer tube 9A and the second outer tube 9B. In this example, the portion formed by the connecting curved tube 11, the end of the first inner tube 5A protruding from the first outer tube 9A, and the end of the second inner tube 5B protruding from the second outer tube 9B is called the "connection portion 13". Furthermore, as... Figure 2 As shown in the example, the cover tube 15 may also extend beyond the "connection portion 13" to cover the ends of the first outer tube 9A and the second outer tube 9B. The extent to which the cover tube 15 covers the first outer tube 9A and the second outer tube 9B can be appropriately determined according to the length required for the insulation of the connection portion.

[0033] In addition, Figure 2 In the example, the diameter of the outer tube 15 is larger than the diameter of the outer tube 9, but the diameter of the outer tube 15 can also be the same as the diameter of the outer tube 9. For example, as in... Figure 3 As illustrated in the modified example, the end faces of both ends of the cover tube 15 can be connected to the end faces of one end of the first outer tube 9A and one end of the second outer tube 9B, respectively. Alternatively, a stepped portion with a diameter smaller than that of the outer tube 9 can be provided at the end of the outer tube 9, and this stepped portion can be inserted into the cover tube 15.

[0034] The cover tube 15 covers the connecting portion 13 in a sealed manner. In addition, although the figure is omitted, the cover tube 15 is provided with an exhaust port for evacuating its interior, and a vacuum layer 7 is formed inside the cover tube 15 when the piping unit 1 is installed.

[0035] In this embodiment, the cover tube 15 has a shape corresponding to the shape of the connecting curved tube 11. That is, the cover tube 15 has a shape in which it is recessed towards the connecting curved tube 11 on the inside of the connecting portion 13, which forms a corner shape that deflects from the first straight tube 3A through the connecting curved tube 11 to the second straight tube 3B, and protrudes towards the side opposite to the connecting curved tube 11 on the outside of the corner shape. In the illustrated example, the cover tube 15 has a first cylindrical portion 15a with a diameter larger than the first outer tube 9A and concentric with the first outer tube 9A, a second cylindrical portion 15b with a diameter larger than the second outer tube 9B and concentric with the second outer tube 9B, and a curved tube 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; for example, it may also be a generally rectangular parallelepiped shape that protrudes towards the side opposite to the connecting curved tube 11 on the inside of the corner shape of the connecting portion 13. However, by setting the cover tube 15 to a shape corresponding to the shape of the connecting curved tube 11, the installation space of the piping unit 1 can be reduced.

[0036] In this embodiment, such as Figure 2 As shown, the cover tube 15 includes a plurality of segments 21. Specifically, in this example, the cover tube 15 is formed by a plurality of segments 21 (three in this example) arranged along the extension direction from the first inner tube 5A to the second inner tube 5B. In other words, the cover tube 15 is formed by a plurality of segments 21 cut with a plane perpendicular to the extension direction from the first inner tube 5A to the second inner tube 5B.

[0037] When the cover tube 15 is formed by multiple segments 21, the segmentation method is not limited to the examples described above. For example, as... Figure 4 As shown, the cover tube 15 can also be formed from two segments 21, which are formed by cutting the first cylindrical portion 15a and the second cylindrical portion 15b in half along a plane along the extended direction. In this way, by forming the cover tube 15 from the segments 21, the assembly of the piping unit 1 at the installation site becomes easier, as will be described later. However, it is not necessary to form the cover tube 15 from the segments 21; it can also be formed as a single tube.

[0038] In addition, such as Figure 1 As shown, in this embodiment, using Figure 2 The connecting curved pipe 11 and the cover pipe 15 shown connect two straight pipes 3 in the section of the piping unit 1 that forms an L-shaped flow path. The T-shaped flow path section 23 is composed of a single double-layered pipe. Additionally, one end of the double-layered pipe of the T-shaped flow path section 23 is connected to the straight pipe 3 via a straight cover pipe 25. However, for the T-shaped flow path section 23 in the piping unit 1, three straight pipes 3 can also be connected using a T-shaped curved pipe and a T-shaped cover pipe 15.

[0039] In addition, such as Figures 5 to 7 As shown, the first straight pipe 3A and the cover pipe 15 can also be flexible at the connection between the first straight pipe 3A and the cover pipe 15. Similarly, although the figure is omitted, the second straight pipe 3B and the cover pipe 15 can also be flexible at the connection between the second straight pipe 3B and the cover pipe 15. Here, the connection between the straight pipe 3 and the cover pipe 15 refers to the part where these pipes interact and the surrounding area, which is the part that can be affected by the bending load caused by the thermal shrinkage of the connecting curved pipe 11. For example, in the case where the straight pipe 3 and the cover pipe 15 overlap, the connection includes the straight pipe 3 and the cover pipe 15 located within the overlap area, as well as the closing portions 25 and 27 of these pipes. In addition, for example, when the straight pipe 3 and the cover pipe 15 are connected with the same pipe diameter ( Figure 3 The connecting portion is the connection point and its surrounding area that includes the closed portion of these pipes. The range of flexibility and the magnitude of allowable displacement in the connecting portion can be appropriately set according to the bending load caused by the thermal contraction of the connecting curved pipe 11 and its surrounding area. Depending on the magnitude of the bending load that may be caused by thermal contraction, the stress can be handled solely by the inherent flexibility of the straight pipe 3, the cover pipe 15 and / or the closed portion 25, the closed portion 27.

[0040] The flexibility of the connecting part can be achieved, for example, by setting it to... Figures 5 to 7 This is achieved in the manner shown. Additionally, in Figures 5 to 7 In the examples shown, a structure that imparts flexibility to the connection is employed, but this is not a limitation; any one of these examples may be used depending on the resulting bending load. Alternatively, a structure illustrated only on the first straight pipe 3A side may also be provided on the second straight pipe 3B side.

[0041] like Figure 5 As shown, the cover tube 15 may also have a displacement-allowing portion 23 at the connection with the first straight tube 3A. Although the figure is omitted, the cover tube 15 may also have a displacement-allowing portion at the connection with the second straight tube 3B. The displacement-allowing portion 23 is, for example, a bellows. When the cover tube 15 is provided with a bellows, the stress caused by bending loads can be mitigated.

[0042] Alternatively or additionally, the sealing portion 25 in the first straight pipe 3A that closes the first outer pipe 9A and the first inner pipe 5A may be flexible, and the sealing portion 27 in the cover pipe 15 that closes the cover pipe 15 and the first outer pipe 9A may be flexible. Similarly, the sealing portion 25 in the second straight pipe 3B that closes the second outer pipe 9B and the second inner pipe 5B may be flexible, and the sealing portion 27 in the cover pipe 15 that closes the cover pipe 15 and the second outer pipe 9B may be flexible. In this way, by making the sealing portions 25 and 27 of the straight pipe 3 and the cover pipe 15 flexible, the bending load that may be generated by the thermal contraction of the connecting curved pipe 11 and its surroundings can be absorbed, and the stress applied to the straight pipe 3 and the cover pipe 15 can be mitigated.

[0043] In addition, such as Figure 6 As shown, even when a structure is adopted in which a step portion 31 with a smaller diameter than the outer tube 9 is provided at the end of the outer tube 9 and the step portion 31 is inserted into the cover tube 15 for connection, the cover tube 15 can have a displacement allowance portion 23 for imparting flexibility to the connection portion with the first straight tube 3A according to the resulting bending load. This displacement allowance portion 23 is, for example, a bellows.

[0044] As a substitute or addition, such as Figure 7 As shown, the sealing portion 25 that closes the first outer tube 9A and the first inner tube 5A in the first straight tube 3A may also have a displacement-allowing structure including unevenness. Similarly, although the figure is omitted, the sealing portion that closes the second outer tube 9B and the second inner tube 5B in the second straight tube 3B may also have a displacement-allowing structure. By making the sealing portion at the end of the straight tube in such a manner, the stress caused by bending loads can be mitigated, and the thermal insulation performance can be improved by increasing the heat transfer distance.

[0045] Next, the assembly method of the piping unit 1 described above will be explained.

[0046] like Figure 8 As shown, the assembly method of this embodiment includes the following steps: preparing the required number, for example, two straight pipes 3; 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 covering the connection 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 sequentially as "straight pipe preparation step S1", "straight pipe connection step S2", and "covering step S3".

[0047] In the straight pipe preparation step S1, after assembling the inner pipe 5 and the outer pipe 9, a vacuum is evacuated from the space between the inner pipe 5 and the outer pipe 9 to create the straight pipe 3. When assembling the inner pipe 5 and the outer pipe 9, appropriate structural components are used as needed, such as spacers to ensure the distance between the inner pipe 5 and the outer pipe 9, and expansion-reducing components like bellows to absorb the difference in thermal shrinkage between the inner pipe 5 and the outer pipe 9. Vacuuming is performed by connecting a vacuum pump to an exhaust port (not shown) provided on the outer pipe 9. A vacuum layer 7 is formed by vacuuming.

[0048] 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, for example, made by welding. However, the connection between the connecting curved pipe 11 and each straight pipe 3 can also be made by other methods. In the following description, the connected first straight pipe 3A, connecting curved pipe 11, and second straight pipe 3B are referred to as "pipe core assembly 27".

[0049] In this embodiment, after the connection step described above, the covering step S3 involves inserting the piping core assembly 27 through each segment 21 of the cover tube 15, and then welding the segment 21 together to cover the connection portion 13. Then, a vacuum is applied to the internal space of the cover tube 15. Alternatively, the integration of the segment 21 can be achieved using methods other than welding.

[0050] Alternatively, if the cover tube 15 is formed as a single component instead of a segmented body 21, for example, the connecting curved tube 11 can be fixed to the inside of the cover tube 15 while the cover tube 15 covers the connecting curved tube 11, and then each straight tube 3 can be connected to the connecting curved tube 11. In this case, the straight tube connection step S2 is performed after the covering step S3. Alternatively, the inner circumference of the cover tube 15 can be set to a size that allows the connecting portion 13 of the piping core assembly 27 to be inserted through, and the connecting portion 13 can be covered by the cover tube 15 after the piping core assembly 27 is assembled.

[0051] Furthermore, in this embodiment, the straight pipe preparation step S1, the subsequent straight pipe connection step S2, and the covering 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 "location 1," and the location where the straight pipe connection step S2 and the covering step S3 are performed is referred to as "location 2." Specifically, location 1 is, for example, a piping manufacturing plant. Location 2 is, for example, a device for installing piping unit 1. The transport of each straight pipe 3 from location 1 to location 2 is carried out, for example, by a transport device such as a truck.

[0052] However, depending on the distance between the first and second locations, the weight and quantity of the straight pipes 3 to be transported, the operator may also carry them out. Furthermore, it is not necessary to perform the straight pipe preparation step S1, the subsequent straight pipe connection step S2, and the covering step S3 at different locations. Also, as mentioned above, the order in which the straight pipe connection step S2 and the covering step S3 are performed is arbitrary.

[0053] The first aspect of the liquefied gas piping unit 1 disclosed herein is a piping unit 1 for conveying liquefied gas, wherein the liquefied gas piping unit 1 comprises: a first straight pipe 3A extending in a straight line, having 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; a second straight pipe 3B extending in a straight line in a direction different from the extension direction of the first straight pipe 3A, having 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; a connecting curved pipe 11 connecting the first inner pipe 5A and the second inner pipe 5B; and a cover pipe 15 covering at least the connecting portion 13 of the connecting curved pipe 11, which includes the first inner pipe 5A and the second inner pipe 5B.

[0054] According to this structure, piping unit 1 is constructed using straight pipes without curved sections, making it easier to manufacture the constituent pipes and reducing manufacturing costs. Furthermore, it reduces the space required for temporary storage and transportation within the factory and at the installation site during the assembly of liquefied gas piping unit 1, further lowering installation costs. In addition, the straight pipes are easier to handle and improve the safety of installation operations.

[0055] The second embodiment of the liquefied gas piping unit 1 disclosed herein is based on the first embodiment of the liquefied gas piping unit 1, wherein the cover pipe 15 has a shape corresponding to the shape of the connecting curved pipe 11. According to this structure, the installation space of the piping unit 1 can be reduced.

[0056] The third embodiment of the liquefied gas piping unit 1 disclosed herein is based on the first or second embodiment of the liquefied gas piping unit 1, wherein the cover pipe 15 includes a plurality of segments 21. According to this structure, the assembly operation of the piping unit 1 at the installation site becomes easier.

[0057] The fourth embodiment of the LPG piping unit 1 disclosed herein is based on any of the first to third embodiments of the LPG piping unit 1, wherein the first straight pipe 3A and the cover pipe 15 are flexible at the connection 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 the connection between the second straight pipe 3B and the cover pipe 15. According to this structure, bending loads that may be generated due to the thermal contraction of the connecting curved pipe 11 can be absorbed, mitigating the stress applied to the straight pipe 3 and the cover pipe 15.

[0058] The assembly method of the LPG piping unit 1 according to the first aspect of this disclosure is a method for assembling the LPG piping unit 1 according to any of the first to fourth aspects. The method includes the following steps: 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, thereby preparing the first straight pipe 3A; combining the second inner pipe 5B and the second outer pipe 9B to prepare the second straight pipe 3B; 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, thereby connecting the first straight pipe 3A and the second straight pipe 3B via the connecting curved pipe 11; and covering the connection portion 13 of the first inner pipe 5A and the second inner pipe 5B, which includes at least the connecting curved pipe 11, with the cover pipe 15.

[0059] According to this structure, the piping unit 1 is assembled using straight pipes without curved sections as units, thus making it easier to manufacture the constituent pipes and reducing manufacturing costs. Furthermore, it reduces the space required for temporary storage and transportation within the factory and at the installation site during the assembly of the liquefied gas piping unit 1, further lowering installation costs. In addition, the straight pipes are easier to handle and improve the safety of installation operations.

[0060] The assembly method of the second aspect of the liquefied gas piping unit 1 disclosed herein assembles the third aspect of the liquefied gas piping unit 1 according to the assembly method of the first aspect. This method includes the following steps: after connecting the first straight pipe 3A and the second straight pipe 3B via the connecting curved pipe 11, the connecting portion 13 is covered by the cover pipe 15 by integrating the divided segments 21. According to this structure, assembly operations can be performed efficiently using the cover pipe 15 composed of the divided segments 21.

[0061] The assembly method of the liquefied gas piping unit 1 according to the third aspect of this disclosure is based on the assembly method of the first or second aspect. This method includes the step of transporting the first straight pipe 3A and the second straight pipe 3B, prepared at a first location, to a second location, where the following steps are performed: 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 structure, by using straight pipes without curved sections, the space required for pipe transportation can be reduced.

[0062] The assembly method of the liquefied gas piping unit 1 according to the fourth aspect of this disclosure is based on the assembly method of the third aspect, wherein the handling is performed by a transport device. According to this structure, by transporting straight pipes without curved sections, the space required by the transport device can be reduced, thus improving transport efficiency. As a result, the installation cost of the piping unit 1 can be significantly reduced.

[0063] As described above, preferred embodiments of the present disclosure 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 present disclosure. Therefore, such structures are also included within the scope of the present disclosure.

Claims

1. A piping unit for liquefied petroleum gas (LPG), used for transporting LPG, wherein, This liquefied gas piping unit has the following features: The first straight pipe extends in a straight line and has a first inner pipe through which the liquefied gas passes and a first outer pipe that covers the first inner pipe through a vacuum layer; The second straight pipe extends in a straight line in a direction different from the extension direction of the first straight pipe, and has a second inner pipe through which the liquefied gas passes and a second outer pipe that covers the second inner pipe through a vacuum layer. A connecting curved tube that connects the first inner tube to the second inner tube; and A cover tube that covers at least the connecting portion of the first inner tube and the second inner tube, including the connecting curved tube.

2. The liquefied gas piping unit according to claim 1, wherein, The cover tube has a shape corresponding to the shape of the connecting curved tube.

3. The liquefied gas piping unit according to claim 1, wherein, The cover tube comprises multiple segments.

4. The liquefied gas piping unit according to claim 1, wherein, The first straight pipe and the cover pipe are flexible at the connection between the first straight pipe and the cover pipe, and / or, The second straight pipe and the cover pipe are flexible at the connection between the second straight pipe and the cover pipe.

5. A method for assembling a liquefied petroleum gas (LPG) piping unit, comprising assembling the LPG piping unit of claim 1, wherein, The assembly method for this liquefied gas piping unit includes the following steps: The first inner tube and the first outer tube are combined, and the space between the first inner tube and the first outer tube is evacuated to form the vacuum layer, thereby preparing the first straight tube; The second inner tube and the second outer tube are combined, and the space between the second inner tube and the second outer tube is evacuated to form the vacuum layer, thereby preparing the second straight tube; The first inner tube of the first straight tube is connected to one end of the connecting curved tube, and the second inner tube of the second straight tube is connected to the other end of the connecting curved tube, thereby connecting the first straight tube and the second straight tube via the connecting curved tube; and The cover tube is used to cover at least the connection portion of the first inner tube and the second inner tube, which includes the connecting curved tube.

6. The assembly method of the liquefied gas piping unit according to claim 5, wherein the liquefied gas piping unit according to claim 3 is assembled, wherein, The assembly method of the liquefied gas piping unit includes the following steps: after connecting the first straight pipe and the second straight pipe via the connecting curved pipe, the connecting portion is covered by the cover pipe by integrating the segmented parts in a split state.

7. The assembly method of the liquefied gas piping unit according to claim 5, wherein, The assembly method for the liquefied gas piping unit includes the following steps: transporting the first straight pipe and the second straight pipe, prepared at the first location, to the second location. At the second location, the following steps are performed: The first straight pipe is connected to the second straight pipe via the connecting curved pipe; and The connecting portion is covered by the cover tube.

8. The assembly method of the liquefied gas piping unit according to claim 7, wherein, The transport is carried out using transportation equipment.

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