System for storing and / or transporting liquefied natural gas

Abstract

The invention relates to a system (30) for storing and / or transporting a liquid gas, comprising at least one container (3) delimiting a main space (20) for containing the liquid gas. The container (3) comprises at least a first space (21), a second space (22) and at least one sealing membrane (10, 10a, 10b) interposed between the first space (21) and the second space (22). The first space (21) constitutes a heat-insulating space for the second space (22). The system (30) for storage and / or transportation comprises a safety device (12) that maintains a seal between the first space (21) and the second space (22) when a first pressure (P1) present within the first space (21) is lower than a second pressure (P2) present within the second space (22) and that brings the first space (21) in a fluidic relationship with the second space (22) when the first pressure (P1) is higher than the second pressure (P2).

Description

Technical Field

[0001] The present invention relates to a system for storing and / or transporting a liquefied gas at low temperature and atmospheric pressure, the system comprising at least one container arranged within a cargo ship. Background Art

[0002] The subject of the present invention is such a storage and / or transport system.

[0003] Liquefied natural gas, commonly denoted by the abbreviation LNG, is typically transported by sea in a carrier ship that includes at least one container housed within a cargo ship and configured to contain liquefied natural gas. The LNG is kept in liquid form within the container to increase the amount of gas transported, with the LNG occupying 1 / 600 of the volume that the gas would occupy in the gaseous state, thus making it easier to transport from one location to another. Additionally, the container is adapted to keep the LNG in liquid form at very low temperatures, particularly at temperatures below -163 °C, at which temperature the LNG is in liquid form at atmospheric pressure.

[0004] Such an LNG container can also be used as a fuel container for certain ships. In other words, such ships load and store LNG in the container and then use the LNG as fuel.

[0005] Each container defines a main space intended to contain LNG. The container includes at least a first space and a second space, with a sealing membrane interposed between the first space and the second space. The first space forms a space thermally insulated from the second space. In other words, upon entering the interior of the container from the outside, at least the first space is encountered, which forms a layer thermally insulated from the second space, then the sealing membrane, which is arranged to ensure the seal between the first space and the second space, and then the second space.

[0006] It should be noted that the container may include two sealing membranes, including a main sealing membrane housed within a secondary sealing membrane.

[0007] Once the membrane is manufactured, it is known to check the seal of the membrane to ensure that there is no leakage from the main volume containing liquefied natural gas into the thermal insulation layer surrounding the main volume.

[0008] Furthermore, a pressure test is typically carried out, during which the sealing membrane is subjected to a test pressure of approximately 20 mbarg, during which the performance, pressure resistance, and possible leakage of the sealing membrane are observed.

[0009] However, this method seems to be risky and may cause considerable damage to the entire container in the event of a malfunction during the above tests. In fact, an operating error may lead to an increase in pressure in the layer surrounding the main volume, which may result in partial or even complete rupture of the sealing membrane. In the common case where the container has a primary sealing membrane and a secondary sealing membrane, both of which surround the main volume containing liquefied natural gas, the consequences are even more severe.

[0010] In addition, there is a need for a storage and / or transportation system including a cargo ship container that is easy to protect the sealing membrane, whether it is a single one or actually a primary and / or secondary one. Summary of the Invention

[0011] The present invention relates to such a background and provides a system for storing and / or transporting a liquefied gas, which system includes at least one container that defines a main space intended to contain a liquefied gas (e.g., liquefied natural gas). The container includes at least a first space, a second space, and at least one sealing membrane between the first space and the second space, and the first space constitutes a heat-insulating space for the second space.

[0012] According to the present invention, the storage and / or transportation system includes a safety device that maintains the seal between the first space and the second space when a first pressure present in the first space is lower than a second pressure present in the second space, and that places the first space and the second space in a fluid relationship when the first pressure is higher than the second pressure.

[0013] The safety device is designed to resist the pressure present in the second space when the pressure present in the second space is higher than the pressure present in the first space. On the other hand, when the pressure in the second space is lower than the pressure in the first space, especially when it has a value of at least equal to 35 mbarg, for example equal to 45 mbarg + / - 9 mbarg, the safety device places the two spaces in a fluid relationship. This prevents any separation or tearing of the sealing membrane, which ensures the separation between the volume of the first space and the volume of the second space.

[0014] According to an optional feature of the present invention, when the first pressure is higher than the second pressure by at least a value equal to 35 mbarg (50 mbarg if appropriate), the safety device places the first space and the second space in a fluid relationship. Advantageously, the value is, for example, equal to 45 mbarg + / - 9 mbarg.

[0015] According to one feature, the primary space forms a secondary space, and the first space is a thermal insulation layer surrounding the secondary space. In this case, the container is provided with only one thermal insulation layer forming the first space, and the secondary space is the internal volume of the container, i.e., the volume for receiving the fluid to be transported and / or stored.

[0016] According to another example, the system for storage and / or transportation includes a second thermal insulation layer surrounding the first space, i.e., a thermal insulation layer surrounding the primary space.

[0017] According to another feature, the secondary space is a first thermal insulation layer surrounding the primary space, and the first space is a second thermal insulation layer surrounding the secondary space. In this case, the container is provided with two thermal insulation layers, which are stacked one on top of the other and surround the primary space dedicated to containing and / or storing the fluid.

[0018] In the two cases mentioned above, each layer is formed by thermal insulation blocks.

[0019] According to the first embodiment, the safety device includes a pipe fluidly connecting the first space and the second space. This solution allows the installation or offset of the elements of the safety device so that the elements are accessible. The elements can be accessible, for example, from the deck of the ship or from a room dedicated for this purpose.

[0020] According to such an embodiment, the safety device includes at least one lid that is liable to rupture once the first pressure exceeds the second pressure, for example, exceeds at least a value equal to 35 mbarg, for example, equal to 45 mbarg + / - 9 mbarg.

[0021] In this case, the safety device includes a first flange and a second flange connected to each other by assembly, the lid is between the first flange and the second flange, and the first flange and the second flange jointly define a channel at least partially accommodating the lid.

[0022] According to an example of the said embodiment, the first flange is accommodated in the first space, and the second flange is arranged in the second space.

[0023] According to a second embodiment that is alternative or supplementary to the first embodiment, the safety device includes at least a plurality of plates connected together and forming at least a part of a sealing membrane, and the safety device includes at least one rupture member, and the at least one rupture member is intended to break the seal of the sealing membrane so that the first space is in fluid communication with the second space.

[0024] According to one feature, the plurality of plates includes at least one central plate and at least two side plates welded to the central plate by lateral welds, and the rupture member includes at least one of the lateral welds. According to such an embodiment, the first space and the second space are associated via the rupture of at least one of the lateral welds.

[0025] More specifically, the central weld can connect the central plate to the heat-insulating blocks that form the first space or the second space. Then, the central weld forms a fastening point of the plate, which has a tendency to deform around the fastening point until the lateral weld breaks.

[0026] In an alternative or complementary manner, the plurality of plates includes at least one central plate and at least two side plates, which are welded to the central plate by lateral welds. Each side plate includes two base plates, which are connected together by an upper plate by an upper weld. The rupture member includes at least one upper weld.

[0027] In the present text, the central weld connects the central plate to the heat-insulating blocks that form the first space or the second space.

[0028] Thus, the rupture member can be manufactured only by the lateral weld, only by the upper weld, or by a combination of the two welds.

[0029] According to another example of an alternative or complementary embodiment of the embodiment described above, the rupture member includes at least one thinning area disposed in at least one of the plurality of plates.

[0030] The thinning area includes a groove disposed on the upper surface and / or the lower surface of at least one of the plurality of plates (for example, one of the side plates).

[0031] Another subject of the present invention is a cargo ship, which includes at least one such system for storage and / or transportation, that is, the cargo ship includes at least one container and safety devices, such as those proposed herein.

[0032] Another subject of the present invention is a method for securing at least one container of a cargo ship, which is implemented by such a system for storage and / or transportation. The securing method includes the step of maintaining the seal between the first space and the second space when a first pressure present in the first space is lower than a second pressure present in the second space. The securing method includes the step of bringing the first space and the second space into a fluid relationship via a safety device when the first pressure is higher than the second pressure, for example, at a value of at least equal to 35 mbarg, particularly equal to a value of 45 mbarg + / - 9 mbarg. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Other features, details, and advantages of the present invention will become clearer by reading the following description on the one hand and referring to the attached schematic diagrams on the other hand, reading multiple examples of the embodiments given as non-limiting indications, wherein:

[0034] Figure 1 is a side view of a cargo ship, which is arranged to be equipped with a system for storing and / or transporting liquefied gas according to the present invention; ​

[0035] Figure 2 is for storing and / or transporting equipment Figure 1 Schematic cross-sectional view of a first variant of an embodiment of the system of the cargo ship shown

[0036] Figure 3 is for storing and / or transporting equipment Figure 1 Schematic cross-sectional view of a second variant of an embodiment of the system of the cargo ship shown

[0037] Figure 4 is for storing and / or transporting equipment Figure 1 Schematic cross-sectional view of a third variant of an embodiment of the system of the cargo ship shown

[0038] Figure 5 is for storing and / or transporting equipment Figure 1 Schematic cross-sectional view of a fourth variant of an embodiment of the system of the cargo ship shown

[0039] Figure 6 is for storing and / or transporting equipment Figure 1 Schematic cross-sectional view of a fifth variant of an embodiment of the system of the cargo ship shown

[0040] Figure 7 is for storing and / or transporting equipment Figure 1 Schematic cross-sectional view of a sixth variant of an embodiment of the system of the cargo ship shown

[0041] Figure 8 is a cross-sectional perspective view of a first implementation form of a safety device, and the safety device is Figures 2 to 7 a component of one of the systems for storing and / or transporting shown

[0042] Figure 9 is Figure 8 a cross-sectional view of the safety device shown

[0043] Figure 10 is a schematic diagram of a cross-section of a first variant of a second implementation form of a safety device, and the safety device is Figures 2 to 7 a component of one of the systems for storing and / or transporting shown

[0044] Figure 11 is Figure 10 a schematic diagram of a cross-section of a second variant of a second implementation form of the safety system shown

[0045] Figure 12 is Figure 10 a schematic diagram of a cross-section of a third variant of a second implementation form of the safety system shown

[0046] ​​​​​​​​​​​​Figure 13 is Figure 10 A schematic cross - section of a fourth variant of a second embodiment of the safety device shown.

[0047] Figure 14 is Figure 10 A schematic cross - section of a fifth variant of a second embodiment of the safety system shown.

[0048] Figure 15 is Figure 10 A schematic cross - section of a sixth variant of a second embodiment of the safety system shown. Detailed implementation

[0049] The features, variants, and different forms of the embodiments of the present invention can be associated together according to various combinations, as long as they are not incompatible or mutually exclusive with respect to each other.

[0050] In particular, if the selection of features is sufficient to provide technical advantages and / or sufficient to distinguish the present invention from the prior art, then variants of the present invention can be envisaged that include only a selection of the features described below that are separated from other features.

[0051] In Figure 1 , a cargo ship 1 is shown, such as an LNG tanker or the like, which has four containers 3, one of the containers 3 being visible herein for ease of understanding. The containers 3 are sealed and insulated and are configured for transporting and / or storing liquefied natural gas. The cargo ship 1 can be arranged for storing and transporting liquefied natural gas only, or can be used as fuel for the operation of the cargo ship 1. It should be understood that the present invention is applicable to cargo ships 1 having any number of containers 3 (a single container 3 or multiple containers 3).

[0052] The cargo ship 1 has a hull 2, which includes at least one outer hull 4 and an inner hull 6, and a plurality of stiffeners 8 extend between the outer hull 4 and the inner hull 6. The outer hull 4 is in contact with the external environment of the cargo ship 1, typically a marine and / or river environment. The inner hull 6 extends at a distance from the outer hull 4 and houses one or more containers 3. Each container 3 includes a main space 20 configured for containing liquefied natural gas.

[0053] According to the present invention, the cargo ship 1 is equipped with a system 30 for storing and / or transporting liquefied natural gas, which system includes the containers 3 and a safety device 12, the safety device 12 being configured to protect the containers 3 from any separation or tearing of the membrane. In other words, the safety device 12 is provided to prevent any damage in case at least one safety condition related to one or more internal pressure states of the containers 3 is not met or is no longer met.

[0054] In Figures 2 to 7 ​​In it, the container 3 includes at least one sealing membrane 10, 10a, 10b between the first space 21 and the second space 22, and the first space 21 accommodates the second space 22. Therefore, the first space 21 is closer to the inner hull 6 of the container 3 than the second space 22.

[0055] According to the present invention, the container 3 is equipped with a safety device 12, which is adapted to protect the sealing membranes 10, 10a, 10b of the container 3 from any pressure difference that would involve deformation of the membranes in the direction of the main space 20 of the container 3.

[0056] Generally speaking, when the first pressure P1 present in the first space 21 is lower than the second pressure P2 present in the second space 22, the safety device 12 maintains the seal between the first space 21 and the second space 22, and when the first pressure P1 is higher than the second pressure P2, the safety device 12 puts the first space 21 and the second space 22 in a fluid relationship. For example, this fluid relationship occurs by means of the tripping of the safety device 12 after the rupture member of the safety device 12 ruptures. This rupture occurs when the first pressure P1 is higher than the second pressure P2 by at least an amount equal to 35 mbarg and, for example, a value equal to 45 mbarg + / - 9 mbarg or 50 mbarg.

[0057] In other words, once the first pressure P1 present outside the volume defined by the sealing membranes 10, 10a, 10b exceeds the second pressure P2 present inside the volume defined by the sealing membranes 10, 10a, 10b by at least an amount equal to 35 mbarg, the safety device 12 acts as a safety element by allowing a fluid relationship between the first space 21 and the second space 22. Once again, in other words, once the sealing membranes 10, 10a, 10b are subjected to an external overpressure with respect to the main volume receiving the liquefied gas, the seal provided by the sealing membranes 10, 10a, 10b is broken to release the overpressure and move it to the second space 22, which allows the pressure to balance on either side of the membrane and thus ensures that there is no deformation.

[0058] Depending on the type of the cargo ship 1 or more precisely, the type of the container 3 included in the cargo ship 1, the safety device 12 is arranged in different positions while ensuring the functions described above in all variants of the arrangement and layout of the safety device 12 described below.

[0059] In Figure 2 and Figure 3In [description], the container 3 includes a single sealing film 10 that separates and defines a first space 21 relative to a second space 22. In other words, by entering from the outside of the container 3 into the inside of the container 3, one encounters the first space 21 that forms a layer thermally insulating from the main space 20, then the single sealing film 10 arranged to ensure a perfect seal between the first space 21 and the second space 22, and then the second space 22 constituted by the main space 20 containing liquefied natural gas. The first space 21 includes heat-insulating blocks formed by heat-insulating panels.

[0060] In Figure 2 [description], the safety device 12 is equipped on the single sealing film 10. In other words, the safety device 12 is directly arranged on the single sealing film 10 and is thus part of the said single sealing film 10. The safety device is here in the plane of one of the walls forming the sealing film.

[0061] In Figure 3 [description], the safety device 12 is equipped on a first pipe 13a that fluidly connects the first space 21 and the second space 22. In other words, the first pipe 13a extends between a first intake nozzle 14a housed in the first space 21 and a first discharge nozzle 14b housed in the second space 22, and the safety device 12 is equipped on the first pipe 13a between the first intake nozzle 14a and the first discharge nozzle 14b. In such a case, the safety device 12 can be placed on the bridge deck.

[0062] In Figures 4 to 7 [description], the container 3 includes a main sealing film 10a that is housed at a certain distance from a secondary sealing film 10b. From the outside of the container 3 to the inside of the container 3, one encounters the heat-insulating layer of the main space 20, then the secondary sealing film 10b, then another heat-insulating layer of the main space 20, and then the main sealing film 10a that defines the main space 20 containing liquefied natural gas.

[0063] The heat-insulating layer of the main space 20 located between the inner hull 6 and the secondary sealing film 10b will hereafter be referred to as the secondary heat-insulating layer 48, and the other heat-insulating layer located between the secondary sealing film 10b and the main sealing film 10a will hereafter be referred to as the main heat-insulating layer 49.

[0064] Each layer includes heat-insulating blocks formed by heat-insulating panels.

[0065] In Figure 4In [description], the safety device 12 is equipped with the main sealing film 10a. In other words, the safety device 12 is directly arranged on the main sealing film 10a. The safety device is herein in the plane of one of the walls forming the main sealing film 10a. In this example, the secondary sealing film 10b does not have the safety device 12. In this case, it should thus be understood that the first space 21 is between the secondary sealing film 10b and the main sealing film 10a. The second space 22 consists of the main space 20 that houses liquefied natural gas.

[0066] In Figure 5 In [description], the safety device 12 is equipped with the secondary sealing film 10b. In other words, the safety device 12 is directly arranged on the secondary sealing film 10b. The safety device is herein in the plane of one of the walls forming the secondary sealing film 10b. In this example, the main sealing film 10a does not have the safety device 12.

[0067] In this case, it should be understood that the first space 21 is between the inner hull 6 and the secondary sealing film 10b. The second space 22 consists of the space between the secondary sealing film 10b and the main sealing film 10a.

[0068] Of course, the present invention covers the case of a double - film container that includes a first safety device 12 arranged on the main sealing film 10a and a second safety device 12 arranged on the secondary sealing film 10b, where the first safety device 12 is between the main space 20 and the main thermal insulation layer 49, and the second safety device 12 is between the main thermal insulation layer 49 and the secondary thermal insulation layer 48.

[0069] In Figure 6 and Figure 7 In [description], the safety device 12 is equipped with the second pipe 13b that fluidly connects adjacent spaces. The second pipe 13b extends between the second intake nozzle 15a and the second discharge nozzle 15b, and the safety device 12 is equipped with the second pipe 13b between the second intake nozzle 15a and the second discharge nozzle 15b.

[0070] More specifically, in Figure 6 In [description], the second intake nozzle 15a is arranged in the first space 21 formed by the secondary thermal insulation layer, and the second discharge nozzle 15b is arranged in the second space 22 formed by the main thermal insulation layer. In the example, no safety device is provided between the main space 20 and the second space 22.

[0071] In Figure 7 In [description], the second intake nozzle 15a is arranged in the main thermal insulation layer 49, and the second discharge nozzle 15b is accommodated in the main space 20. In this example, no safety device is provided between the main thermal insulation layer 49 and the secondary thermal insulation layer 48.

[0072] The present invention also covers the case of a double - film container equipped with two safety devices 12, as Figure 6 and Figure 7 shown.

[0073] In Figure 8 and Figure 9 there is shown a first embodiment of the safety device 12. According to said embodiment, the safety device 12 includes a rupture member 16 between a first flange 17a and a second flange 17b connected together by a component 18. The assembly means is for example a bolt.

[0074] Preferably, the rupture system 16 includes at least one cover which is liable to rupture once a first pressure P1 exceeds a second pressure P2. For this purpose, the first flange 17a and the second flange 17b jointly define a channel 19 which extends between a first outlet 31 defined by the first flange 17a and a second outlet 32 defined by the second flange 17b. It should be understood that the first outlet 31 is arranged to extend within a first space 21, the second outlet 32 is intended to extend within a second space 22, and the cover 16a forms part of for example a sealing membrane. It should also be noted that the channel 19 at least partly houses the cover 16a, and the flanges 17a, 17b are removable to allow the cover 16a to be replaced when it ruptures, thus restoring the seal between the first space 21 and the second space 22.

[0075] In Figures 10 to 15 there is shown a second embodiment of the safety device 12, the safety device 12 including a plurality of plates 19a, 19b, 19', 19'' which are welded together and arranged in respective planes which are parallel or even merged with each other. Said plates are part of a sealing membrane equipped with the safety device 12.

[0076] Figures 10 to 15 Each includes a left figure and a right figure. The left figure shows the state of the membrane when the second pressure P2 is higher than the first pressure P1 (i.e., when the safety device 12 maintains the seal between the first space 21 and the second space 22), and the right figure shows the state of the membrane when the second pressure P2 is lower than the first pressure P1 (i.e., when the membrane tends to deform by expanding towards the interior of the container). This state is just before a fluid relationship is established between the volume of the first space 21 and the volume of the second space 22. Once this state is exceeded, the safety device 12 places the first space 21 in fluid relationship with the second space 22 in order to balance the pressure between said spaces.

[0077] According to Figure 10 a first variant of an embodiment of the shown embodiment, the safety device 12 includes at least one central plate 19a and two side plates 19b which are welded to the central plate 19a via lateral welds 41b. A central weld 41a fixes the central plate 19a to a connecting plate 46 which is also fixed to a heat insulating block of the first space 21.

[0078] In Figures 10 to 15In the example shown, the side plate 19b does not have a mechanical connection with the connecting plate 46 to allow movement of the side plate.

[0079] It should be noted that the two side plates 19b extend in the same plane. In the state before the safety device 12 ruptures, the ends of each side plate 19b partially overlap the central plate 19a.

[0080] It should also be noted that the heat insulation block includes a cavity arranged in its thickness and turned towards the main space. This cavity receives at least the connecting plate 46 and the central plate 19a.

[0081] The safety device 12 includes a rupture member 44, which in this case takes the form of a lateral weld 41b. By the deformation as shown in the Figure 10 right figure, the side plate 19b pivots around the lateral weld 41b under the influence of the pressure difference between the first space 21 and the second space 22, which causes the rupture of the lateral weld 41b. This pivoting is facilitated by the fact that the central plate 19a is firmly attached to the connecting plate 46 by the central weld 41a.

[0082] According to Figure 11 a second variant of the embodiment according to the illustrated embodiment form, the safety device 12 includes at least two central plates 19a and two side plates 19b, and each side plate 19b is welded to the adjacent central plate 19a by a lateral weld 41b. The two central welds 41a each connect the central plate 19a to the connecting plate 46 of the heat insulation block in the first space 21.

[0083] According to such an embodiment, the two side plates 19b extend in the same first plane, while the two central plates 19a extend in the same second plane, and the first plane and the second plane are parallel but different in the state before the safety device 12 ruptures. It should be noted that each central plate 19a is connected to the connecting plate 46 by central welds 41a arranged opposite to each other.

[0084] The safety device 12 includes a rupture member 44 which in this case takes the form of one or more lateral welds 41b. By the deformation as shown in the Figure 11 right figure, the side plate 19b pivots around the lateral weld 41b under the influence of the pressure difference between the first space 21 and the second space 22, which causes the rupture of the lateral weld 41b. This pivoting is facilitated by the fact that each central plate 19a is firmly attached to the connecting plate 46 separately by the central weld 41a.

[0085] According to Figure 12In a third variant embodiment of the illustrated embodiment, the safety device 12 includes a single central plate 19a and two side plates 19b, and the two side plates 19b are welded to the central plate 19a by lateral welds 41b. A central weld 41a fixes the central plate 19a to a connection plate 46, and the connection plate 46 is fixed to the heat insulation block of the first space 21. Each side plate 19b is composed of two base plates 19' connected together by an upper plate 19". The upper plate 19" is connected to each base plate 19' by an upper weld represented as 41'. Thus, on each side of the central plate 19a, one of the base plates 19' is fastened to the upper plate 19" by an upper weld 41' and to the central plate 19a by a lateral weld 41b.

[0086] According to such an embodiment, the four side plates 19' extend in the same first plane, while the two upper plates 19" extend in the same third plane, and the first plane and the third plane are parallel but different in the state before the safety device 12 breaks. Thus, the first plane is between the third plane and the second plane, and the single central plate 19a extends in the second plane.

[0087] One of the base plates 19' includes a lateral weld 41b connecting the edge of the base plate 19' to the central plate 19a and an opposite edge covered by the upper plate 19". The upper plate 19" includes a first edge, and the first edge is connected to the face of the base plate 19' by an upper weld 41'.

[0088] The other base plate 19' includes a first edge and another edge fastened to the upper plate 19" by an upper weld 41', and the upper weld 41' extends between the second edge of the upper plate 19" and the surface of the base plate 19'.

[0089] As Figure 10 in the case, the single central plate 19a is connected to the connection plate 46 by a single central weld 41a.

[0090] The safety device 12 includes a rupture member 44 in the form of one or more lateral welds 41b and / or one or more upper welds 41' employed herein, wherein the upper weld is provided between the base plate 19' and the central plate 19a or between the upper plate 19" and one and / or the other of the base plates 19' adjacent to the upper plate 19".

[0091] By as Figure 12The deformation shown in the right figure, each component composed of the base plate 19' and the upper plate 19" pivots around the lateral weld 41b that connects the base plate 19' to the central plate 19a under the action of the pressure difference between the first space 21 and the second space 22, and this pressure difference causes the rupture of the lateral weld 41b and / or the upper weld 41'. This pivoting is facilitated by the fact that the central plate 19a is firmly attached to the connecting plate 46 through the central weld 41a.

[0092] According to Figure 13 In the fourth variant of the illustrated embodiment, each side plate 19b is provided with a thinning area, which is arranged on the upper surface 43 of the side plate 19b, and the upper surface 43 is the surface of the side plate 19b facing the second space 22. Such a local thinning area forms a rupture member 44, which functionally meets the same criteria as the welding described above. According to an example of the embodiment, the thinning area is in the form of a groove 42.

[0093] It should be understood that such a groove 42 forms a fragile area of the material, which can rupture during the deformation of the side plate 19b, just like one of the lateral welds 41b, as Figure 13 shown in the figure on the right.

[0094] Regarding the form and arrangement of the central plate 19a, the side plates and the welds, reference is made to Figure 10 the description.

[0095] According to Figure 14 In the fifth variant of the illustrated embodiment, the thinning area forming the rupture member is arranged on the lower surface 45 of the side plate 19b, and the lower surface 45 is the surface of the side plate 19b opposite to the heat insulation block. Therefore, this variant of the embodiment differs from Figure 13 only in the position of the thinning area.

[0096] It should also be noted that such a groove 42 is obtained indifferently by stamping or by removing material, whether it is arranged on the upper surface 43 of the side wall 19b or on the lower surface 45.

[0097] Regarding the form and arrangement of the central plate 19a, the side plates and the welds, see Figure 13 the description.

[0098] Figure 15 The sixth variant of the embodiment is shown in. For the same components, see Figure 12 the description. In such an example, each upper plate 19" is provided with a thinning area, which is produced, for example, in the form of a groove 42 arranged on the lower surface 47 of the upper plate 19", and the lower surface 47 is the surface of the upper plate 19" opposite to the heat insulation block. It should be understood that such a thinning area forms a fragile area of the material, which ruptures during the deformation of the side plate 19b.

[0099] Of course, without departing from the scope of the present invention, the present invention is not limited to the examples just described and the number of layouts that can be provided by the examples.

[0100] The present invention just described actually achieves the set objective and serves to prevent any bulging of the membrane, i.e., any deformation of the plate forming the membrane, due to an operating error during the pressure resistance test of the insulating space of a container for storing and / or transporting LNG. Variations not described herein can be implemented without departing from the context of the present invention as long as, according to the present invention, the variations include a system for storing and / or transporting a liquid gas, the system comprising at least one container and at least one safety device intended to protect the hermetic membrane of such a container.

Claims

1. A system (30) for storing and / or transporting a liquefied gas, comprising at least one container (3), said container (3) defining a main space (20) intended to contain the liquefied gas and comprising at least a first space (21), a second space (22) and at least one sealing membrane (10, 10a, 10b) between said first space (21) and said second space (22), said first space (21) being constituted by the insulating space of said second space (22), characterized in that, the system (30) for storing and / or transporting comprises a safety device (12), said safety device (12) maintaining the seal between said first space (21) and said second space (22) when a first pressure (P1) present in said first space (21) is lower than a second pressure (P2) present in said second space (22), and putting said first space (21) and said second space (22) in fluid communication when said first pressure (P1) is higher than said second pressure (P2).

2. The system (30) for storing and / or transporting according to claim 1, wherein, when said first pressure (P1) is higher than said second pressure (P2) by at least a value equal to 35 mbarg, said safety device (12) puts said first space (21) and said second space (22) in fluid communication.

3. The system (30) for storing and / or transporting according to claim 1 or 2, wherein, said main space (20) forms said second space (22), and said first space (21) is an insulating layer surrounding said second space (22).

4. The system (30) for storing and / or transporting according to claim 3, comprising a second insulating layer surrounding said first space (21).

5. The system (30) for storing and / or transporting according to claim 1 or 2, wherein, said second space (22) is a first insulating layer surrounding said main space (20), and said first space (21) is a second insulating layer surrounding said second space (22).

6. The system (30) for storing and / or transporting according to any one of claims 1 to 5, wherein, said safety device (12) comprises pipes (13a, 13b) fluidly connecting said first space (21) and said second space (22).

7. The system (30) for storing and / or transporting according to any one of claims 1 to 5, wherein, said safety device (12) comprises at least one lid (16a) which is liable to break once said first pressure (P1) exceeds said second pressure (P2).

8. The system (30) for storing and / or transporting according to claim 7, wherein, The safety device (12) includes a first flange (17a) and a second flange (17b) connected to each other by a component (18), the cover (16a) being interposed between the first flange (17a) and the second flange (17b), and the first flange (17a) and the second flange (17b) jointly defining a passage (19) that at least partially houses the cover (16a).

9. The system (30) for storage and / or transportation according to any one of claims 1 to 5, wherein, the safety device (12) includes at least a plurality of plates (19a, 19b, 19', 19'') that are connected together and form at least a part of the sealing film, the safety device (12) includes at least one rupture member (44), and the at least one rupture member (44) is intended to break the seal of the sealing film so that the first space (21) is in fluid communication with the second space (22).

10. The system (30) for storage and / or transportation according to claim 9, wherein, the plurality of plates (19a, 19b, 19', 19'') includes at least one central plate (19a) and at least two side plates (19b), the at least two side plates (19b) are welded to the central plate (19a) by lateral welds (41b), and the rupture member (44) includes at least one of the lateral welds (41b).

11. The system (30) for storage and / or transportation according to claim 9 or 10, wherein, the plurality of plates (19a, 19b, 19', 19'') includes at least one central plate (19a) and at least two side plates (19b), the side plates (19b) are welded to the central plate (19a) by lateral welds (41b), each side plate (19b) is composed of two base plates (19'), the two base plates (19') are connected together by an upper weld (41') by an upper plate (19''), and the rupture member (44) includes at least one of the upper welds (41').

12. The system (30) for storage and / or transportation according to any one of claims 9 to 11, wherein, the rupture member (44) includes at least one thinning region (42) arranged in at least one of the plurality of plates (19a, 19b, 19', 19'').

13. The system (30) for storage and / or transportation according to claim 12, wherein, the thinning region (42) includes a groove arranged on the upper surface (43) and / or the lower surface (45) of at least one of the plurality of plates (19a, 19b, 19', 19'').

14. A cargo ship (1) at least including the system (30) for storage and / or transportation according to any one of claims 1 to 13.

15. A method for securing at least one container (3) of a cargo ship (1), the method being implemented by the system (30) for storing and / or transporting liquefied gas according to any one of claims 1 to 13, characterized in that, The safe method comprises the step of maintaining the seal between the first space (21) and the second space (22) when a first pressure (P1) present in the first space (21) is lower than a second pressure (P2) present in the second space (22), and consists in that the safe method comprises the step of putting the first space (21) and the second space (22) in fluid communication via a safety device (12) when the first pressure (P1) is higher than the second pressure (P2), for example by a value of at least 35 mbarg.

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