Apparatus for storing liquefied gas

Abstract

The present invention relates to a device for storing liquefied gas, comprising a supporting structure (1) and a sealed and insulated tank arranged in the supporting structure (1), the supporting structure (1) comprising a dome structure (19) projecting vertically from an upper supporting wall (3) towards the outside of the tank, the dome structure (19) comprising vertical dome walls (22) projecting upwards from the upper supporting wall (3) and each comprising an upper end, the dome structure (19) having a seating wall (23) extending horizontally and having a peripheral abutment region (33), the dome structure (19) comprising a covering (25) covering the passage and welded in a sealed manner to the seating wall (23), the covering (25) being welded to at least one intermediate plate (34) welded to the seating wall (23) in the peripheral abutment region (33).

Description

Technical Field

[0001] The present invention relates to the field of storage devices for liquefied gases, the storage devices comprising sealed and insulated tanks arranged in a support structure.

[0002] In particular, the present invention relates to the field of sealed and insulated tanks for the storage and / or transport of liquefied gases at cryogenic temperatures, such as tanks for transporting liquefied petroleum gas (also known as LPG) having temperatures, for example, between -50°C and 0°C, or tanks for transporting liquefied natural gas (LNG) at approximately -162°C. These tanks can be installed on shore or on floating structures. In the case of floating structures, the tanks can be used for transporting liquefied gases or for receiving liquefied gases used as fuel for propelling the floating structure.

[0003] The present invention relates more particularly to a storage device of the type described above, the storage device comprising a dome structure that protrudes upward from the upper support wall of a supporting structure and is for passage by at least one pipe for loading or unloading a tank. Background Technology

[0004] Document WO2015155377 discloses an apparatus for storing liquefied gases, comprising: a support structure including a double hull of a ship; and a sealed and insulated tank disposed within the support structure. This apparatus includes the aforementioned document... Figure 4 The dome structure shown serves as a penetration point for various tank installations, such as pipes used for loading or unloading the tank. The dome structure projects upwards from an upper support wall. The dome structure includes a vertical support wall that rises above the ship's deck, and a horizontal wall positioned at the top of the vertical support wall. The horizontal wall supports a covering, which essentially comprises a metal covering wall and insulation inserted into the top of the dome structure.

[0005] To secure the metal cladding walls and the horizontal walls of the dome structure and ensure the dome structure's seal, it is known to create weld lines along the periphery of the metal cladding walls. When the pressure inside the tank is higher than the ambient pressure, this pressure difference exerts a force on the cladding pointing outwards, causing the metal cladding walls to buckle under stress. This stress can degrade the aforementioned weld lines and thus lead to sealing problems in the dome structure, especially when the tank is used to store gases at pressures higher than those in conventional tanks with membranes.

[0006] Therefore, this dome structure arrangement is not entirely satisfactory. Summary of the Invention

[0007] Therefore, a potential concept of the present invention is to propose an apparatus for storing liquefied gases, the apparatus including a dome structure having better pressure resistance.

[0008] Accordingly, according to one embodiment, the present invention provides an apparatus for storing liquefied gas, the apparatus comprising a support structure and a sealed and insulated tank disposed in the support structure, the support structure including an upper support wall and the tank including a top wall fastened to the upper support wall, the upper support wall and the top wall being partially interrupted to define an opening, the support wall including a dome structure projecting from the upper support wall surrounding the opening toward the outside of the tank and defining a channel for at least one conduit through which liquefied gas is loaded into the tank or liquefied gas is stored. Gas is unloaded from the tank. The dome structure includes dome walls that project from an upper support wall and each include an upper end. The dome structure includes a seating wall that is fastened to the upper end of the vertical dome wall. The seating wall extends horizontally and includes a peripheral abutment region that abuts the channel and projects from the vertical dome wall toward the channel. The dome structure includes a cover that covers the channel and is welded to the seating wall in a sealed manner. The cover is welded to at least one intermediate plate that is welded to the seating wall in the peripheral abutment region.

[0009] Therefore, since the cover is welded to the peripheral adjacent area, which is the area of ​​the seat wall closest to the center of the dome structure, the torque applied to the weld is reduced when the pressure inside the tank is higher than the pressure outside the tank. This allows for limiting the deflection of the cover and improving the pressure resistance of the weld that secures the cover to the seat wall. Furthermore, the use of an intermediate plate allows for the distribution of force across a larger number of welds. Additionally, the intermediate plate constitutes an additional reinforcement between the cover and the seat wall, capable of absorbing some of the force through deformation.

[0010] According to the implementation method, such a device may have one or more of the following features.

[0011] According to one embodiment, the intermediate plate is welded to the peripheral adjacent area along the inner edge of the peripheral adjacent area. This allows the intermediate plate to be fastened to the sitting wall by means of a corner weld line, which is easy to implement and ensures satisfactory fastening performance.

[0012] According to one embodiment, the cover is welded to a plurality of intermediate plates arranged around the channel, and each of the plurality of intermediate plates is welded to the seating wall in a peripheral adjacent region. Preferably, each of the plurality of intermediate plates is welded to the seating wall along the inner edge of the peripheral adjacent region in the peripheral adjacent region.

[0013] According to one embodiment, the intermediate plates, or each intermediate plate, protrude toward the interior of the dome structure. Therefore, the intermediate plates extend toward the channel beyond the inner edge of the adjacent peripheral area.

[0014] According to one embodiment, the intermediate plate is welded to the cover using at least one continuous or discontinuous weld line extending along at least one edge of the intermediate plate.

[0015] According to one embodiment, the intermediate plate is welded to the cover using at least two weld lines extending along at least two edges of the intermediate plate, said at least two edges being arranged on two sides of the inner edge of the peripheral adjacent region. This allows force to be distributed over a large weld surface and the intermediate plate to be fastened to the cover by means of corner weld lines, which are easy to implement and ensure satisfactory fastening performance.

[0016] According to one embodiment, the cover is welded to the seating wall in a sealed manner using an intermediate frame arranged around the channel and the at least one intermediate plate.

[0017] According to one embodiment, the intermediate frame is welded to the seating wall by means of at least one sealing weld line extending along the inner or outer periphery of the intermediate frame. According to one embodiment, the sealing weld line is a continuous weld line.

[0018] According to one embodiment, the cover is welded to the intermediate frame by means of at least one sealing weld line. Preferably, the at least one sealing weld line extends along the outer periphery of the cover. Thus, the weld line ensuring a seal between the cover and the seating wall is arranged outside the area that additionally secures the cover to the seating wall, such that the force generated by the positive pressure present inside the tank exerts only a small stress on the weld line. According to one embodiment, the sealing weld line is a continuous weld line.

[0019] According to one embodiment, the intermediate frame is welded to the seating wall using two weld lines extending along the inner and outer peripheries of the intermediate frame, respectively. According to a variation of the first embodiment, the weld line extending along the outer periphery of the intermediate frame is continuous and sealed, while the weld line extending along the inner periphery of the intermediate frame is discontinuous. According to a variation of the second embodiment, the weld line extending along the inner periphery of the intermediate frame is continuous and sealed, while the weld line extending along the outer periphery of the intermediate frame is discontinuous. Finally, according to a variation of the third embodiment, both weld lines are sealed, thereby further enhancing the reliability of the seal.

[0020] According to one embodiment, the tank includes a tank wall anchored against each of the dome walls, each tank wall including a primary sealing membrane for contacting liquefied gas contained within the tank. The dome structure includes a profiled frame, and the primary sealing membrane is welded against this profiled frame, which is welded to the peripheral adjacent region of the seat wall via a sealing weld line. Therefore, under the action of thermal contraction of the primary sealing membrane, the primary sealing membrane applies a force to the peripheral adjacent region of the seat wall in a direction opposite to the force applied to the peripheral adjacent region due to the pressure exerted on the cover by the vapor phase of the liquefied gas. This further restricts the deflection of the seat wall and the cover.

[0021] In addition, the middle plate and the adjacent area of ​​the perimeter form a region for heat conduction from the cover to the irregular frame, which limits the temperature drop of the irregular frame and thus limits the thermal stress acting on the irregular frame.

[0022] According to one embodiment, the irregular frame has an L-shaped cross-section, the irregular frame having the L-shaped cross-section includes a first branch and a second branch that are perpendicular to each other, the first branch being welded to a primary sealing membrane and to a peripheral adjacent region and extending vertically, and the second branch extending horizontally and being fastened to a fastening protrusion that protrudes downward from the peripheral adjacent region of the sitting wall toward the top wall.

[0023] According to one embodiment, the irregular frame includes reinforcing corner plates, each of which has a first edge pressed against a first branch and a second edge pressed against a second branch.

[0024] According to one embodiment, the device includes a loading / unloading tower that passes through a channel defined by a dome structure. The loading / unloading tower includes at least two masts that pass through a cover and are fastened to each other by intersecting members. Both vertical masts form pipes for loading or unloading tanks.

[0025] According to one embodiment, each tank wall, including the top wall and each tank wall anchored to abut against one of the dome walls, comprises: a secondary thermal barrier held against a support structure; a secondary sealing membrane resting against the secondary thermal barrier; a primary thermal barrier resting against the secondary sealing membrane; and a primary sealing membrane resting against the primary thermal barrier and for contacting liquefied gas contained in the tank.

[0026] The tank according to one embodiment of the above-described embodiments can form part of an onshore storage facility—for example, an onshore storage facility for storing LNG—or can be installed in an offshore or deep-water floating structure, particularly a methane carrier or methane carrier vessel, a floating storage and regasification unit (FSRU), a floating production storage and offloading (FPSO) unit, etc. In the case of a floating structure, the tank can be used to receive liquefied natural gas used as fuel for propelling the floating structure.

[0027] According to one embodiment, the present invention relates to a vessel for transporting fluids, the vessel including equipment of the type described above.

[0028] According to one embodiment, the vessel includes a twin hull that forms a supporting structure.

[0029] According to one embodiment, the present invention also provides a transfer system for transferring fluids, the system comprising: the aforementioned vessel; an isolation line arranged to connect a tank to a floating or shore-based storage facility; and a pump for transferring fluid flow from the floating or shore-based storage facility through the isolation line to the vessel's tank or transferring fluid flow from the vessel's tank through the isolation line to the floating or shore-based storage facility.

[0030] According to one embodiment, the present invention also provides a method for loading or unloading such a vessel, wherein fluid is transported from a floating or shore-based storage facility to a vessel's tank via an insulated pipeline, or fluid is transported from a vessel's tank to a floating or shore-based storage facility via an insulated pipeline. Attached Figure Description

[0031] The invention will be better understood in the following description of several specific embodiments of the invention, which are given by way of example only with reference to the accompanying drawings and without limitation, and other objects, details, features and advantages of the invention will become more apparent.

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[0042] Combination Figure 1 The following describes a support structure 1, a sealed and insulated tank for storing liquefied gas, which is intended to be secured against the support structure 1. The support structure 1 is, for example, formed by the double hull of a ship. The support structure 1 has a polyhedral overall shape. The support structure 1 has two support walls 2, namely a front support wall and a rear support wall, which are octagonal in shape. Figure 1 Only the aft support wall of support wall 2 is shown. The front and aft walls 2 are, for example, cofferdam walls extending laterally relative to the longitudinal direction of the ship. Support structure 1 also includes upper support wall 3, lower support wall 4, and lateral support walls 5, 6, 7, 8, 9, and 10.

[0043] A sealed and insulated tank for storing liquefied gas includes multiple tank walls, which are respectively anchored to one of the support walls 2, 3, 5, 6, 7, 8, 9, 10 of the support structure 1.

[0044] like Figure 2As shown, each wall of the tank, along its thickness direction, sequentially comprises from the outside to the inside: a secondary insulation barrier 12, which includes an insulating element 13 fastened to a support structure 1; a secondary sealing membrane 14, which is anchored to the insulating element 13 of the secondary insulation barrier 12; a primary insulation barrier 15, which includes an insulating element 16 fastened to the insulating element 13 of the secondary insulation barrier 12 or fastened to the support structure 1 and resting against the secondary sealing membrane 14; and a primary sealing membrane 17, which is anchored to the insulating element 16 of the primary insulation barrier 15 and is intended to contact the liquefied gas contained in the tank.

[0045] like Figure 3 and Figure 7 As shown, the upper support wall 3 and the top wall 11 are partially interrupted to define the opening 18. The support structure 1 includes a dome structure 19 that projects upward from the upper support wall 3 surrounding the opening 18 and defines a channel 24 through which one or more pipes 20, 21, 47 designed for loading or unloading the tank pass.

[0046] The dome structure 19 includes vertical dome walls 22. For example, when the dome structure 19 has a square or rectangular shape, the number of dome walls 22 is four. Here, the dome walls 22 project upwards from the upper support wall 3 and rise above the deck of the ship. The dome structure 19 also includes a seating wall 23 at the top of the dome walls 22, which extends horizontally around the passage 24 formed by the dome walls 22 and thus forms a coaming with the dome walls 22. The seating wall 23 supports a cover 25 through which one or more pipes 20, 21 designed for loading or unloading tanks pass. The cover 25 includes a metal cover plate and an insulation element (not shown), which is fastened to abut the lower surface of the metal cover plate and inserted into the dome structure 19. Figure 3 and Figure 7 As shown, according to one embodiment, the cover 25 includes a mesh structure of stiffeners 48, each of which is formed by a metal plate welded against the upper surface of the metal cover.

[0047] In addition, the support structure also includes a reinforcing member 49, which is fastened below the seating wall 23 and pressed against the upper support wall 3 and the dome wall 22.

[0048] As described above Figure 2 As described, there is a multi-layered structure of tanks against the dome wall 22, but there is no multi-layered structure of tanks at the level of the cover of the dome structure 19.

[0049] exist Figure 3 In the illustrated embodiment, the loading / unloading tower 26 passes through the interior of the passage 24 defined by the dome structure 19. The loading / unloading tower 26 includes three vertical masts 20, 21. Figure 3 The diagram shows two of the three vertical masts 20, 21, each secured to the other by a cross member 27. The three vertical masts 20, 21 pass through the cover 25 of the dome structure 19 and extend over approximately the entire height of the tank. The loading / unloading tower 26 includes a base (not shown) that cooperates with support legs secured to the lower support wall 4 and thus serves to hold the loading / unloading tower 26 in a vertical position.

[0050] According to one embodiment, each of the masts 20 and 21 is hollow, passes through the covering of the dome structure 19, and forms:

[0051] - Piping used for loading tanks with liquefied gas.

[0052] - A conduit for unloading liquefied gas from a tank, and therefore, this conduit is associated with an unloading pump fastened to the lower end of the conduit, or

[0053] - Emergency shaft: In the event of a failure of the unloading pump, the emergency pump and unloading pipeline can be lowered.

[0054] Combination Figure 4 The following describes the structure at the top of the tank wall that secures the cover 25, and more particularly the metal plate of the cover 25, to the seating wall 23 and the tank wall that is secured to the dome wall 22.

[0055] The cover 25 is securely fastened to the seating wall 23 in a sealed manner. For this purpose, the cover 25 is welded in a sealed manner to a metal intermediate frame 28, which itself is pre-welded in a sealed manner to the seating wall 23. Advantageously, the intermediate frame 28 is welded in a sealed manner to the seating wall 23 using two consecutive fillet welds 29 and 30, which extend along the inner and outer peripheries of the intermediate frame 28, respectively. Furthermore, the periphery 39 of the cover 25 rests against the upper surface of the intermediate frame 28 and is welded in a sealed manner to said upper surface of the intermediate frame 28 by means of a consecutive fillet weld 31. In the illustrated embodiment, the intermediate frame 28 rests at least partially against the outer region 32 of the seating wall 23, which is the region positioned outside the dome wall 22 relative to the passage 24.

[0056] Furthermore, the seating wall 23 includes a peripheral border region 33 that adjoins the passage 24 and projectes horizontally toward the passage 24 relative to the dome wall 22. Additionally, the cover 25 is secured to the seating wall 23 by means of a plurality of intermediate metal plates 34. Figure 4 , Figure 5 and Figure 6 The diagram shows an intermediate metal plate 34. The intermediate plate 34 is regularly arranged along the peripheral adjacent region 33 and protrudes along the internal direction of the dome structure 19 relative to the inner edge 37 of the peripheral adjacent region 33. According to... Figure 5 and Figure 6 In the exemplary embodiment shown, the intermediate plate 34 has a narrow elongated shape following the inner edge 37 of the peripheral adjacent area 33, and the intermediate plate 34 has an L-shaped corner bracket at the corner between two adjacent dome walls 22.

[0057] Each intermediate plate in the intermediate plates 34 is pre-welded to the cover 25 before being welded to the peripheral adjacent area 33 of the seating wall 23. Figure 4 In the illustrated embodiment, each of the intermediate plates 34 is corner-welded to abut the inner surface of the cover 25 by at least two weld lines 35, 36. The two weld lines 35, 36 are formed along two edges of the intermediate plate 34 located on two sides of the inner edge 37 of the peripheral adjacent region 33. According to a variation of one embodiment, the intermediate plate 34 is welded to abut the inner surface of the cover 25 at each of its edges.

[0058] Furthermore, the seating wall 23 and each intermediate plate 34 are fastened to each other by means of a fillet weld 38 formed along the inner edge 37 of the peripheral adjacent region 33 and abutting against the lower surface of each intermediate plate 34. It is particularly advantageous to fasten the cover 25 to the peripheral adjacent region 33 using the intermediate plates 34 because: when the pressure inside the tank is higher than the ambient pressure, the pressure applied to the cover 25 can be withstood, and thus the pressure applied to the weld line 31, formed further outward of the dome structure 19, can be reduced, ensuring that the cover 25 is securely fastened to the seating wall 23 in a sealed manner. Additionally, the intermediate plates 34 are advantageous because they allow force to be distributed over a larger welded surface. Furthermore, the intermediate plates 34 constitute an intermediate reinforcement between the cover 25 and the seating wall 23, and when the pressure inside the tank is higher than the ambient pressure, the intermediate plates 34 can elastically deform to partially absorb the force applied to the cover 25. Finally, since the welding lines 36, 37, 38 used to fasten the cover 25 to the peripheral adjacent area of ​​the sitting wall 23 are positioned as close as possible to the center of the dome structure 19, the torque applied to these welding lines 36, 37, 38 under positive pressure in the tank is reduced.

[0059] In addition, such as Figure 4 As shown, the dome structure 19 includes a shaped frame 40, a primary sealing membrane 17 is welded to the shaped frame 40, and the shaped frame 40 forms a holding region for the primary sealing membrane, which is the area located at the top of the dome structure 19, in which the primary sealing membrane 17, mounted to abut against the dome wall 22, is anchored to the support structure 1. The shaped frame 40 is welded to the peripheral abutment region 33 of the sitting wall 23 in a manner that continuously surrounds the peripheral abutment region 33 of the sitting wall 23 to ensure a seal for the primary sealing membrane 17.

[0060] Due to the thermal shrinkage of the primary sealing film 17, the primary sealing film 17 applies a force to the peripheral adjacent region 33 of the seat wall 23. This force is directed in the opposite direction to the force applied to the peripheral adjacent region 33 due to the pressure applied to the cover 25. Therefore, this arrangement structure allows for further restriction of the deflection of the seat wall 23 and the cover 25.

[0061] like Figure 4 and Figure 8As shown, the irregular frame 40 has an L-shaped cross-section, meaning that the irregular frame 40 includes a first branch 41 and a second branch 42 that are perpendicular to each other. The first branch 41 extends vertically in the plane of the primary sealing membrane 17. The first branch 41 has a free end that is welded to the peripheral adjacent region 33 of the seating portion 23 via a welding portion 43. Additionally, at the top of the dome structure 19, the primary sealing membrane 17 rests against the first branch 41 and is welded to the first branch 41. The second branch 42 extends parallel to the thickness direction of the wall. Furthermore, the second branch 42 is welded via a welding portion 45 to abut against a fastening protrusion 44 that protrudes vertically downward from the peripheral adjacent region 33 of the seating wall 23.

[0062] according to Figure 9 In the embodiment variation shown, the irregular frame 40 includes reinforcing corner plates 46, each of which has a first edge pressed against a first branch 41 of the irregular frame 40 and a second edge pressed against a second branch of the irregular frame 40.

[0063] The dome structure 19 also includes a secondary enclosing panel 50 (in Figure 4 (shown in the middle), the secondary sealing plate 50 is welded to the peripheral adjacent region 33 of the sitting wall 23 in a manner that continuously surrounds the peripheral adjacent region 33 of the sitting wall 23, and the secondary sealing membrane of the tank wall, which is installed to abut against the dome wall 22, is fastened to the secondary sealing plate.

[0064] The liquefied gas intended to be stored in tanks can be, in particular, liquefied natural gas (LNG), which is a gaseous mixture primarily containing methane and one or more other hydrocarbons. The liquefied gas can also be ethane or liquefied petroleum gas (LPG), which is a mixture of hydrocarbons obtained through the refining of petroleum and primarily containing propane and butane.

[0065] Reference Figure 10 A cross-sectional view of a methane transport vessel 70 shows a sealed and insulated tank 71, which is generally prismatic in shape, installed within the vessel's twin hulls 72. The walls of tank 71 include: a primary sealing barrier for contact with the LNG contained within the tank; a secondary sealing barrier disposed between the primary sealing barrier and the vessel's twin hulls 72; and two isolation barriers disposed between the primary sealing barrier and the secondary sealing barrier, and between the secondary sealing barrier and the twin hulls 72, respectively.

[0066] In a manner known per se, the loading / unloading pipeline 73, located on the upper deck of the vessel, can be connected by means of appropriate connectors to a seaport or port terminal to transfer LNG cargo from or to tank 71.

[0067] Figure 10 An example of a marine terminal is shown, comprising a loading and unloading station 75, underwater pipelines 76, and shore-based equipment 77. The loading and unloading station 75 is a fixed offshore facility comprising a movable boom 74 and a tower-like structure 78 supporting the boom 74. The boom 74 carries a bundle of flexible isolation tubes 79 that can be connected to a loading / unloading pipeline 73. The directional boom 74 is suitable for methane transport vehicles of all sizes. Connecting pipes (not shown) extend within the tower-like structure 78. The loading and unloading station 75 allows for the loading of methane transport vessels 70 from shore-based equipment 77 or the unloading of methane transport vessels 70 to shore-based equipment 77. The shore-based equipment 77 includes a liquefied gas storage tank 80 and a connecting pipe 81 connected to the loading or unloading station 75 via the underwater pipeline 76. The underwater pipeline 76 allows liquefied gas to be transferred over a greater distance, such as 5 km, between the loading or unloading station 75 and the shore-based equipment 77, thereby enabling the methane transport vessel 70 to be kept at a greater distance from the coast during loading and unloading operations.

[0068] To generate the pressure required for the transfer of liquefied gas, pumps installed on the vessel 70 and / or installed in the shore equipment 77 and / or installed in the loading and unloading station 75 are used.

[0069] Although the invention has been described in conjunction with several specific embodiments, it is quite obvious that the invention is by no means limited thereto, and the invention includes all the technical equivalents and combinations thereof of the described apparatus that fall within the scope of protection claimed by the invention.

[0070] The use of the verbs “having,” “including,” or “comprising,” and their variations, does not preclude the presence of other elements or steps besides those mentioned in the claims.

[0071] In the claims, any reference numerals in parentheses should not be construed as limiting the claims.

Claims

1. An apparatus for storing liquefied gas, the apparatus comprising a support structure (1) and a sealed and insulated tank disposed in the support structure (1), the support structure (1) comprising an upper support wall (3) and the tank comprising a top wall (11) fastened to the upper support wall (3), the upper support wall (3) and the top wall (11) being partially interrupted to define an opening (18), the support structure (1) comprising a dome structure (19) projecting vertically from the upper support wall (3) surrounding the opening toward the outside of the tank and the dome structure (19) defining a channel (24) for passage of at least one conduit (20, 21) for loading liquefied gas into or unloading liquefied gas from the tank, the dome structure (19) comprising a dome. The dome structure (19) includes a wall (22), the dome wall (22) protruding from the upper support wall (3) and each including an upper end, the dome structure (19) including a seat wall (23) fastened to the upper end of the dome wall (22), the seat wall (23) extending horizontally and including a peripheral abutment region (33) abutting the passage (24) and the peripheral abutment region (33) protruding from the vertical dome wall (22) toward the passage (24), the dome structure (19) including a cover (25) covering the passage and welded to the seat wall (23) in a sealed manner, the cover (25) being welded to at least one intermediate plate (34) which is welded to the peripheral abutment region (33) along the inner edge (37) of the peripheral abutment region (33).

2. The device according to claim 1, wherein, The cover (25) is welded to a plurality of intermediate plates (34) arranged around the channel and each of the plurality of intermediate plates (34) is welded to the seating wall (23) along the inner edge (37) of the peripheral adjacent area (33).

3. The device according to claim 1 or 2, wherein, The intermediate plate (34) or each intermediate plate (34) protrudes toward the interior of the dome structure (19), and wherein the intermediate plate (34) is welded to the cover (25) by means of at least one welding line (35, 36) extending along at least one edge of the intermediate plate (34).

4. The device according to claim 3, wherein, The intermediate plate (34) or each intermediate plate (34) is welded to the cover (25) by means of at least two welding lines (35, 36) extending along at least two edges of the intermediate plate (34), the at least two edges being arranged on the two sides of the inner edge (37) of the peripheral adjacent area (33).

5. The device according to claim 1 or 2, wherein, The cover (25) is welded to the seating wall (23) in a sealed manner by using an intermediate frame (28) arranged around the channel (24) and at least one of the intermediate plates (34).

6. The device according to claim 5, wherein, The intermediate frame (28) is welded to the seating wall (23) by means of at least one sealing weld line (29, 30) extending along the inner or outer periphery of the intermediate frame (28).

7. The device according to claim 5, wherein, The cover (25) is welded to the intermediate frame (28) by means of at least one sealing weld line (31).

8. The device according to claim 1 or 2, wherein, The tank includes tank walls anchored against each of the dome walls (22), each tank wall including a primary sealing membrane (17) for contacting the liquefied gas contained in the tank, the dome structure (19) including a shaped frame (40), the primary sealing membrane (17) being welded against the shaped frame (40), and the shaped frame (40) being welded to the peripheral adjacent area (33) of the seat wall (23) via a sealing weld line (43).

9. The device according to claim 8, wherein, The irregular frame (40) has an L-shaped cross-section, and the irregular frame (40) with the L-shaped cross-section includes a first branch (41) and a second branch (42) perpendicular to each other. The first branch (41) is welded to the primary sealing membrane (17) and to the peripheral adjacent area (33). The first branch (41) extends vertically, and the second branch (42) extends horizontally and is fastened to a fastening protrusion (44), which protrudes from the peripheral adjacent area (33) of the seat wall (23) toward the top wall (11).

10. The device according to claim 9, wherein, The irregular frame (40) includes reinforcing corner plates (46), each of which has a first edge pressed against the first branch (41) and a second edge pressed against the second branch (42).

11. The device according to claim 1 or 2, the device comprising a loading / unloading tower (26) passing through the channel (24) defined by the dome structure (19), the loading / unloading tower (26) comprising at least two vertical masts passing through the cover (25) and secured to each other by a cross member (27), both of the vertical masts forming a conduit for loading or unloading the tank.

12. The device according to claim 1 or 2, wherein, Each tank wall, including the top wall (11) and each tank wall anchored against the vertical dome wall (22), comprises: a secondary insulation barrier (12) held against the support structure (1); a secondary sealing membrane (14) placed against the secondary insulation barrier (12); a primary insulation barrier (15) placed against the secondary sealing membrane (14); and a primary sealing membrane (17) placed against the primary insulation barrier (15) and for contacting the liquefied gas contained in the tank.

13. A vessel (70) for transporting fluids, the vessel comprising the equipment according to claim 1 or 2.

14. A fluid transfer system, the system comprising: The vessel according to claim 13; isolation lines (73, 79, 76, 81) arranged to connect the vessel's tank (71) to a floating or shore-based storage facility (77); and a pump for transferring fluid from the floating or shore-based storage facility to the vessel's tank via the isolation lines, or transferring fluid from the vessel's tank to the floating or shore-based storage facility via the isolation lines.

15. A method for loading or unloading the vessel (70) according to claim 13, wherein, Fluid is transported from a floating or shore storage facility (77) to the tank (71) of the vessel via insulated pipelines (73, 79, 76, 81), or fluid is transported from the tank (71) of the vessel to a floating or shore storage facility (77) via insulated pipelines (73, 79, 76, 81).

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