Sealed and thermally insulated tank for storing liquefied gas

Abstract

Leak-proof and thermally insulating tank for the storage of a liquefied gas. The invention relates to a tank, the tank comprising a tank wall (100) including a sealing structure for hermetically sealing a space between the sealing membrane and the load-bearing wall (1000), the sealing structure comprising a first metal structure (6) and a second metal structure (9); the first metal structure comprising a first height (61) and a first base (62); the second metal structure comprising a second height (91) and a second base (92), the sealing membrane comprising corrugations and flat parts situated between the corrugations, the flat parts of the sealing membrane being hermetically fixed to the second base (92);the sealing membrane comprising caps (40) fixed in a watertight manner to the longitudinal ends of the longitudinal corrugations and to the second base (92) to close said longitudinal ends. Figure for the abbreviation: 6;

Description

Title of the invention: A sealed and thermally insulated tank for the storage of a liquefied gas technical field

[0001] The invention relates to the field of leak-proof and thermally insulated tanks for the storage and / or transport of liquefied gases, such as tanks for transporting Liquefied Petroleum Gas (also called LPG) at temperatures ranging, for example, from -50°C to 0°C, or for transporting Liquefied Natural Gas (LNG) at approximately -162°C at atmospheric pressure. These tanks can be installed on land or on a floating structure. In the case of a floating structure, the tank can be used for transporting liquefied gas or for receiving liquefied gas to serve as fuel for the propulsion of the floating structure.

[0002] In the case of a floating structure, the tank may be intended for the transport of liquefied gas or for receiving liquefied gas used as fuel for the propulsion of the floating structure. Technological background

[0003] A sealed and thermally insulated LNG storage tank arranged in a supporting structure has a multilayer structure, namely from the outside to the inside of the tank, a secondary thermally insulating barrier anchored against the supporting structure, a secondary sealing membrane which rests on the secondary thermally insulating barrier, a primary thermally insulating barrier which rests on the secondary sealing membrane and a primary sealing membrane which rests on the primary thermally insulating barrier and which is intended to be in contact with the liquefied natural gas stored in the tank.

[0004] During the manufacture of a LNG carrier tank, a lateral opening is sealed at the end of the tank fabrication process by attaching a section of the supporting structure onto which a section of the tank is mounted. Publication KR 10 20110011155A describes such a lateral opening. This lateral opening is sometimes called a hull breach. Before sealing the hull breach, it is necessary to check the watertightness of the tank wall sealing membranes already fabricated around the hull breach.

[0005] Publication WO2020260572 provides a leak test method, according to a first example, for checking the leak tightness of the sealing membrane of an unfinished portion of a tank, i.e. a portion of a tank intended to be associated with one or more other portions of a tank in order to finalize the manufacture of said tank.

[0006] There is a need to control the watertightness of a sealing membrane comprising corrugations. In particular, there is a need to control the watertightness of a metallic sealing membrane comprising corrugations. Summary of the invention

[0007] An idea underlying the invention is to provide a means for forming a sealed enclosed space within a tank wall comprising a metallic sealing membrane comprising corrugations.

[0008] According to one embodiment, the invention provides a sealed and thermally insulating tank for the storage of a liquefied gas, the tank comprising a tank wall resting against a load-bearing wall, the tank wall comprising at least one sealing membrane and at least one thermally insulating barrier arranged between the sealing membrane and the load-bearing wall, the thermally insulating barrier comprising a row of end blocks extending in a transverse direction; the tank wall further comprising a sealing structure extending between the sealing membrane and the load-bearing wall in a direction corresponding to the thickness of the tank wall in order to hermetically enclose at least one space between the sealing membrane and the load-bearing wall, the sealing structure extending along the end blocks and terminating the tank wall in a longitudinal direction perpendicular to the transverse direction, the sealing structure being hermetically fixed on one side to the load-bearing wall and, on the other side, to the sealing membrane; the sealing structure comprising a first metal structure and a second metal structure; the first metal structure comprising a first height and a first base; the first base being hermetically fixed to the load-bearing wall; the first height extending along the thickness direction of the tank wall; the second metal structure comprising a second height extending along the thickness direction of the tank wall and a second base, the second base covering and being fixed to an upper wall of the end blocks; the sealing membrane comprising a plurality of corrugations extending in the longitudinal direction and flat parts situated between the corrugations, the flat parts of the sealing membrane being fixed in a watertight manner to the second base; the sealing membrane further comprising a plurality of caps fixed in a watertight manner to longitudinal ends of the longitudinal corrugations and to the second base to close said longitudinal ends.

[0009] Thanks to these characteristics, the sealing membrane, the caps, the sealing structure and the load-bearing wall hermetically enclose at least one space in the tank wall.

[0010] It is then possible to check the tightness of the sealing membrane of this closed, sealed space formed.

[0011] In order to test the leak-tightness of the tank wall under test, the sealed enclosed space is connected to a means of positive or negative pressure. Such a means of negative pressure is, for example, a vacuum pump connected to the sealed enclosed space or any other means of negative pressure capable of reducing the pressure in the sealed enclosed space.

[0012] Activating the vacuum device reduces the pressure within the sealed enclosure relative to the external environment. This vacuum is, for example, in the range of -500 to -800 mbar, preferably -800 mbar. The test is performed for 24 to 48 hours, and the pressure variation is recorded to determine if any leaks are present.

[0013] Furthermore, the first and second metal structures facilitate the installation of the sealing structure at one end of the tank wall. The presence of two parts—the first and second metal structures—makes it possible to compensate for any potential flatness defect along the row of end blocks.

[0014] According to embodiments, such a tank may include one or more of the following characteristics.

[0015] According to one embodiment, at least one said cap comprises a cap foot and a cap body, the cap foot being fixed in a watertight manner to the second base, the cap body being fixed in a watertight manner to the longitudinal end of a said longitudinal corrugation.

[0016] The cap foot facilitates the positioning of the cap and therefore the welding of the cap onto the second base, as well as the welding with the corrugation by an operator. Furthermore, the cap foot reduces the risk of burning or damaging the material positioned beneath the cap foot.

[0017] For example, a ratio of a width 1 of the cap foot to a height h of the cap body is between 1 and 1 / 6.

[0018] The cap foot facilitates welding the cap onto the second base. Furthermore, it limits the welding energy input to the prefabricated blocks by lengthening the weld bead, thus preventing burns or fires on the prefabricated blocks during welding operations.

[0019] According to one embodiment, the cap foot has a generally flat shape, the cap foot and the cap body forming an angle with respect to each other of between 80° and 100°, for example 90°.

[0020] For example, the cap foot has a generally rectangular shape. For example, the angle formed by the cap foot and the cap body is 90°. In other words, a 90° angle is formed between the cap foot and the cap body.

[0021] According to one embodiment, the cap foot has truncated corners on a face opposite to the cap body.

[0022] According to one embodiment, the second metal structure is located above the first metal structure in the thickness direction of the tank wall.

[0023] The first metal structure is fixed in a watertight manner to the load-bearing wall. The first metal structure extends along the row of end blocks in the transverse direction and in the thickness direction of the tank wall.

[0024] In one embodiment, the first metal structure comprises a first height and a first base. The first base is fixed in a watertight manner to the load-bearing wall. The first height extends along the thickness direction of the tank wall.

[0025] The first height and the first base are connected to each other in a watertight manner at the level of a lower end, along the thickness direction of the tank wall, of an end block of the row of end blocks.

[0026] For example, the first height and the first base are directly fixed to each other and form a right angle at the lower end of said end block of the row of end blocks. Thus, along the direction of the row of end blocks, the first height and the first base form a right L.

[0027] The second metal structure covers and is fixed to an upper wall of the end blocks and, in a watertight manner, to the flat parts of the sealing membrane.

[0028] The second metal structure extends along the row of end blocks in the transverse direction and in the thickness direction of the tank wall.

[0029] In one embodiment, the second metal structure comprises a second height and a second base. The second height extends along the thickness direction of the tank wall. The second base covers and is fixed to an upper wall of the end insulating blocks. Furthermore, the second base is sealed to the flat portions of the sealing membrane.

[0030] The second height and the second base are connected to each other in a watertight manner at the level of an upper end, along the thickness direction of the tank wall, of an end block of the row of end blocks.

[0031] For example, the second height and the second base are directly fixed to each other and form a right angle at the upper end of said end block of the row of end blocks. Thus, depending on the direction of the row of end blocks, the second height and the second base form an inverted L of 180°.

[0032] According to one embodiment, the cap foot is fixed to the second base by a lap weld.

[0033] According to one embodiment, the first base is fixed in a hermetic manner to the load-bearing wall by continuous welding.

[0034] According to one embodiment, said end block comprises a plurality of lateral anchoring strips, the lateral anchoring strips being fixed to a lateral wall of said end block; the first height being fixed to the lateral anchoring strips.

[0035] According to one embodiment, the first height is fixed to the lateral anchor strips by spot welding. Such welding facilitates the removal of the first metal structure once the watertightness has been checked.

[0036] According to one embodiment, said end block comprises a plurality of anchoring strips; the anchoring strips being fixed to an upper wall of said end block; the second base being fixed to the anchoring strips in a watertight manner.

[0037] According to one embodiment, a first thermal protection sheet is positioned on one of the side walls of an end block; the first thermal protection sheet being covered by the first height.

[0038] According to one embodiment, the secondary sealing membrane is made of composite material.

[0039] According to one embodiment, the undulations extend periodically along the transverse direction of the tank wall.

[0040] According to another aspect, the invention provides a method for testing the leak-tightness of the sealing membrane in a tank according to the invention; the method comprising:

[0041] - to depressurize the insulating barrier with respect to an external environment the tank wall; and

[0042] - measure a parameter representative of the evolution of the pressure inside the insulating barrier after the tank wall has been depressurized.

[0043] For example, the pressure drop is in the range of -500 to -800 mbar. For example, the test is carried out for 24 to 48 hours and the pressure variation is recorded in order to determine if any leaks are present.

[0044] According to one embodiment, prefabricated elements are anchored within the internal space of the supporting structure to form the tank wall. Each prefabricated element comprises a portion of a thermally insulating barrier and a portion of a sealing membrane. These prefabricated elements can be anchored to the supporting structure in a regular grid pattern.

[0045] According to one embodiment, the thermally insulating barrier comprises a plurality of standard insulating blocks distributed in a regular grid within it. The standard insulating blocks may be rectangular blocks.

[0046] At one end of the tank wall, i.e. where the thermally insulating barrier terminates, the tank wall includes end blocks.

[0047] According to one embodiment, the end blocks are rectangular pavers and are arranged in a row. An end block may include a bottom wall (also called a base wall) and a top wall (also called a lid wall).

[0048] The lower and upper walls can be connected to each other by four side walls. In this case, the side walls support the upper wall. The end blocks then form coffers.

[0049] Conversely, a lining can rest against the lower wall and support the upper wall.

[0050] The thermally insulating barrier thus comprises a row of end blocks terminating the tank wall. The row of end blocks extends in a transverse direction across the tank wall.

[0051] The end blocks may be thermally insulating. For example, the end blocks may comprise a thermally insulating material similar to or even identical to the thermally insulating material of the main insulating blocks of the thermally insulating barrier.

[0052] If the end blocks are boxes, they can be filled with an insulating material, for example glass or rock wool, or synthetic foam with a density of less than 60 kg / m3. If the end blocks comprise only a lower wall and an upper wall resting against a lining, this mechanically load-bearing lining can be thermally insulating, for example polyurethane foam, possibly reinforced with fibers.

[0053] The sealing structure extends along the end blocks and terminates the tank wall in a longitudinal direction of the tank wall, the longitudinal direction being perpendicular to the transverse direction.

[0054] Furthermore, in order to hermetically seal at least one space between the sealing membrane and the load-bearing wall, the sealing structure is hermetically fixed, on the one hand, to the load-bearing wall and, on the other hand, to the sealing membrane.

[0055] The sealing structure comprises a first metal structure and a second metal structure. The sealing structure thus comprises at least two parts and is therefore not made of a single piece. The first and second metal structures facilitate the installation of the structure sealing at the end of the tank wall. The presence of two parts - the first metal structure and the second metal structure - makes it possible to compensate for any lack of flatness along the row of end blocks as well as a variation in the thickness of the thermally insulating barrier.

[0056] The first metal structure and the second metal structure being part of the sealing structure, they are connected to each other in a watertight manner within it.

[0057] It is possible to connect, in a watertight manner, the first metal structure and the second metal structure according to several possibilities.

[0058] One possibility is to attach the first metal structure to the second metal structure without any intermediate parts between them. In other words, the first metal structure and the second metal structure are attached directly to each other. In this case, the second metal structure can overlap the first metal structure or vice versa.

[0059] A second possibility is to provide one or more intermediate pieces that provide a watertight connection between the first metallic structure and the second metallic structure. These intermediate pieces can be metallic, for example, a third metallic structure, or non-metallic. For example, it is possible to position a gasket between the first metallic structure and the second metallic structure to ensure the watertightness of the sealing structure.

[0060] According to one embodiment, the sealing membrane is a primary sealing membrane, the thermally insulating barrier is a primary thermally insulating barrier and the row of end blocks is a row of primary end blocks; the tank wall further comprising a secondary sealing membrane arranged between the primary thermally insulating barrier and the load-bearing wall and a secondary thermally insulating barrier arranged between the load-bearing wall and the secondary sealing membrane, the secondary thermally insulating barrier comprising a row of secondary end blocks;The sealing structure further comprises a third metal structure arranged between the first metal structure and the second metal structure, the third metal structure comprising a third height and a third base, the third base being fixed to an upper wall of the secondary end blocks, the third height being fixed in a watertight manner to the first height, the second height being fixed in a watertight manner to the third height.

[0061] In this embodiment, the sealing structure comprises a third metal structure connecting, in a watertight manner, the first metal structure to the second metal structure.

[0062] According to one embodiment, the third height is fixed in a watertight manner to the first height by a continuous weld.

[0063] According to one embodiment, the second height is fixed in a watertight manner to the third height by continuous welding.

[0064] According to one embodiment, said secondary end block comprises a plurality of upper secondary anchoring strips; the upper secondary anchoring strips being fixed to an upper wall of said secondary end block; the second base being fixed to the upper secondary anchoring strips.

[0065] According to one embodiment, the second base is attached to the upper secondary anchor strips by spot welding. Such welding facilitates the removal of the second metal structure once the seal has been checked.

[0066] According to one embodiment, a second thermal protection sheet is positioned on one side on an upper wall of said secondary end block and on the other side on a lateral wall of said secondary end block; the second thermal protection sheet being covered by the third height and the third base.

[0067] According to another aspect, the invention provides a vessel for the transport of a cold liquid product, the vessel comprising a double hull and a sealed and thermally insulated tank according to the invention disposed in the double hull.

[0068] According to another aspect, the invention provides a transfer system for a cold liquid product, the system comprising a vessel according to the invention, insulated pipes arranged to connect the vessel's tank to a floating or land-based storage facility, and a pump to drive a flow of cold liquid product through the insulated pipes from or to the floating or land-based storage facility to or from the vessel's tank.

[0069] According to another aspect, the invention provides a method for loading or unloading a ship according to the invention, in which a cold liquid product is conveyed through insulated pipes from or to a floating or land-based storage facility to or from the ship's tank. Brief description of the figures

[0070] The invention will be better understood, and other objects, details, features and advantages thereof will become more apparent from the following description of several particular embodiments of the invention, given solely by way of illustration and not limitation, with reference to the accompanying drawings.

[0071] Fig. 1 is an exploded perspective view that schematically represents a first manufacturing step of a portion of a tank wall according to a first embodiment.

[0072] Fig.2 is a view analogous to Fig.1, which schematically represents a second manufacturing step of the tank wall according to the first embodiment.

[0073] [Fig.3] is an enlarged view of zone III of [Fig.2] schematically represents the tank wall according to the first embodiment when the second step is completed.

[0074] Fig. 4 is a perspective view, which schematically represents a third manufacturing step of the tank wall according to the first embodiment.

[0075] Fig. 5 is a view analogous to Fig. 4, which schematically represents a fourth manufacturing step of the tank wall according to the first embodiment.

[0076] Fig. 6 is a view analogous to Fig. 4, which schematically represents a fifth manufacturing step of the tank wall according to the first embodiment.

[0077] Fig.7 is a view analogous to Fig.4, which schematically represents a sixth manufacturing step of the tank wall according to the first embodiment.

[0078] Fig. 8 schematically represents an enlarged view of zone VIII of Fig. 7.

[0079] Figure [Fig.9] schematically represents a cap according to a second embodiment.

[0080] Fig. 10 is a schematic cutaway representation of a tank of a methane tanker and a loading / unloading terminal for this tank. Description of the implementation methods

[0081] By convention, the terms "lower" and "upper" are used to define the relative position of one element with respect to another, respectively in the direction of the outside or the inside of the tank as in the horizontal wall shown in [Fig. 1]. However, the following description is applicable to any wall regardless of its orientation in the Earth's gravitational field.

[0082] A particular embodiment, given solely by way of illustration and not limitation, is now described with reference to the attached Figures 1 to 9. The figures focus on an end portion of the tank wall near a 90-beam breach, the remainder of the tank wall being able to be manufactured using methods known elsewhere, for example as described in document FR2903165.

[0083] The sealed and thermally insulated liquefied natural gas storage tank arranged in a load-bearing structure 1000 has a multilayer structure, with from outside to inside the tank, there is a secondary thermally insulating barrier 3 anchored against the supporting structure 1000, a secondary sealing membrane 2 which rests on the secondary thermally insulating barrier 3, a primary thermally insulating barrier 5 which rests on the secondary sealing membrane 2 and a primary sealing membrane 4 which rests on the primary thermally insulating barrier 5 and which is intended to be in contact with the liquefied natural gas stored in the tank.

[0084] Known prefabricated elements, partially shown, can be anchored to a large portion of the supporting structure 1000 to form the two insulating barriers and the secondary sealing membrane 2 of the tank. Each prefabricated element comprises a portion of the secondary thermally insulating barrier 3, a portion of the secondary sealing membrane 2, and a portion of the primary thermally insulating barrier 5. These prefabricated elements are anchored in a regular grid pattern to the supporting structure 1000.

[0085] The secondary sealing membrane 2 of a prefabricated block is a rigid waterproof film 317 bonded to the secondary thermally insulating barrier.

[0086] The primary thermally insulating barrier portion of a prefabricated block only partially covers the secondary waterproofing membrane 2, without covering a peripheral portion of the secondary waterproofing membrane. A flexible waterproof film 11 is fixed to said peripheral portion of the secondary waterproofing membrane of two adjacent prefabricated elements in order to ensure the continuity of the secondary waterproofing membrane 2.

[0087] More specifically, each prefabricated block comprises, from the outside of the tank to the inside of the tank, a bottom plate 311, a secondary insulating lining, the rigid sealing film 317, a primary insulating lining and a lid plate 512.

[0088] The base plate 311 and the secondary insulating lining form a first block 31 of substantially parallelepiped shape covered by the rigid waterproof film 317.

[0089] The primary insulating lining and the cover plate 512 form a second block 51 of substantially parallelepiped shape resting on the rigid waterproof film.

[0090] The base plate 311 and the cover plate 512 are, for example, made of plywood. The secondary insulating lining and the primary insulating lining are, for example, made of polyurethane foam, optionally reinforced with fibers. The rigid waterproof film 317 is, for example, a composite material, i.e., consisting of an aluminum sheet sandwiched between two layers of glass fibers and resin.

[0091] In such a prefabricated block, the base plate 311, the secondary insulating lining and the rigid sealing film 317 have dimensions in a plane perpendicular to the thickness direction of the tank greater than the dimensions of the primary insulating lining and the cover plate 512 so that a peripheral edge of the rigid sealing film 317 is not covered by the primary insulating lining.

[0092] During the manufacture of the tank, such prefabricated blocks are anchored to the supporting structure 1000, for example, the inner wall of a double ship hull, in a side-by-side manner. A flexible waterproofing film 11 is applied to the peripheral (non-visible) edge of the rigid waterproofing film 317 of two side-by-side prefabricated blocks so as to ensure continuity of the seal between the rigid waterproofing films 317 of two adjacent prefabricated blocks. This flexible waterproofing film 11 is, for example, made of triplex®, that is, comprising an aluminum sheet between two layers of glass fibers bonded by a flexible resin such as rubber.

[0093] The secondary sealing membrane 2 is formed by the rigid waterproofing films 317 of the prefabricated blocks and the flexible waterproofing films 11 connecting the prefabricated blocks. The continuity of the secondary sealing membrane 2 is thus obtained.

[0094] Other details on such prefabricated blocks, their arrangement, or other constituent elements of the tank are described for example in document FR2903165.

[0095] Figures 1 and 2 illustrate a truncated view of the tank wall 100 resting against the load-bearing wall 1000. As illustrated in Figures 1 and 2, the tank wall 100 is interrupted in the longitudinal L and transverse T directions near the rim breach 90, which is a rectangular window extending in these two directions.

[0096] In what follows, the interrupted tank wall in the longitudinal direction L is described.

[0097] The secondary thermally insulating barrier 3 comprises the aforementioned prefabricated blocks and, at the longitudinal end L of the tank wall 100, a row of secondary end blocks 32. The row of secondary end blocks 32 extends in the transverse direction T of the tank wall and terminates the secondary thermally insulating barrier 3 of the tank wall 100.

[0098] The secondary end blocks 32 are caissons comprising a lower wall (or bottom plate) and an upper wall 322 (or lid plate) connected to each other by side walls 321 and 323. The side walls 323 extend in the longitudinal direction L and the side walls 321 extend in the transverse direction T. A first side wall 321 (not visible) is positioned opposite the adjacent prefabricated block in the longitudinal direction L and a second side wall 321 terminates the tank wall 100.

[0099] In addition, the secondary end blocks 32 include lateral anchor strips 101 and upper secondary anchor strips 102. The strips Secondary upper anchors 102 are fixed to the upper wall 322 and lateral anchor strips 101 are fixed to the second lateral wall 321 terminating the tank wall 100. The secondary upper anchor strips 102 form a row of anchor strips extending in the transverse direction T. Similarly, the lateral anchor strips 101 form a row of anchor strips extending in the transverse direction T.

[0100] The lateral anchor strips 101 and the upper secondary anchor strips 102 are fixed by riveting or screwing.

[0101] The lateral anchor bands 101 and the upper secondary anchor bands 102 are metallic, for example stainless steel.

[0102] As illustrated in [Fig.1], during the manufacture of the tank, a first metal structure 6 is fixed to the load-bearing wall 1000 and to the lateral anchoring strips 101. [Fig.2] illustrates the state of the tank when the first metal structure 6 is fixed to the load-bearing wall 1000 and to the lateral anchoring strips 101.

[0103] The first metal structure 6 is made of stainless steel.

[0104] The first metal structure 6 comprises a first base 62 and a first height.

[0105] The first base 62 and the first height 61 form a right angle with respect to each other. The first base 62 is securely fixed to the load-bearing wall 100 by a continuous weld. The first height 61 is welded to the lateral anchor strips 101. Thus, the right angle of the first metal structure 6 follows a right angle formed by the load-bearing wall 1000 and the second lateral wall 321. In the transverse direction, the first height and the first base form a right "L".

[0106] Furthermore, a first thermal protection sheet 601 is positioned on the second side wall 321. During the fastening of the first metal structure 6, the first height 61 covers the first thermal protection sheet 601. The first thermal protection sheet 601 protects the second side wall 321 from welding heat during the assembly of several segments of the first metal structure 6. A joining weld 88 between two aligned segments is shown in exploded view in [Fig. 1], noting that these segments can be assembled successively in practice, in which case the joining weld 88 is made directly above the first thermal protection sheet 601. It is possible to distribute several thermal protection sheets 601 along the second side wall 321.

[0107] In addition, as illustrated in Figures 2 and 3, the tank wall 100 includes a third metal structure 8.

[0108] The third metal structure 8 comprises a third base 82 and a third height 81. The third base 82 and the third height 81 form a right angle with respect to each other at the upper end of the secondary end blocks 32 of the row of secondary end blocks 32. Thus, in the transverse direction, the third height 81 and the third base 82 form an inverted "L" of 180°.

[0109] The third base 82 is fixed to the upper secondary anchor strips 102 by a spot weld. The third height 81 is fixed to the first height 61 in a watertight manner by a continuous weld ([Fig.3]).

[0110] Thus, the first height 61 and the third height 81 complete the secondary layer of the tank wall 100.

[0111] A second thermal protection sheet 801 is positioned straddling the upper wall 322 and the second side wall 321. In other words, the second thermal protection sheet 801 is positioned on either side of the upper edge of the secondary end block 32. The second thermal protection sheet 801 is covered by the third metal structure 8.

[0112] As illustrated in Figures 1, 2, 4 and 5, the primary thermally insulating barrier 5 comprises at the longitudinal end L of the tank wall 100, a row of primary end blocks 52. The row of primary end blocks 52 extends in the transverse direction T of the tank wall and terminates the primary layer of the tank wall 100.

[0113] In addition, primary insulating blocks 87 fill the spaces between the second blocks 51 and cover the flexible waterproof film 11, according to the known technique.

[0114] In addition, primary anchor strips 202 are fixed to the cover plates 512 of the second blocks 51 and the primary insulating blocks 87. The primary anchor strips 202 form a row of anchor strips extending in the transverse direction T. The primary anchor strips 202 are fixed by riveting or screwing. The primary anchor strips 202 are metallic, for example, stainless steel.

[0115] The primary end blocks 52 have a larger dimension than the secondary end blocks 32 in the longitudinal direction L. As illustrated in [Fig.5], the primary end blocks 52 cover one longitudinal end of the prefabricated blocks, the secondary end blocks 32 and the third base 82.

[0116] The primary end blocks 52 are fixed with an adhesive strip 55 to the secondary waterproofing membrane 2. The adhesive strip 55 is positioned on either side of the row of secondary end blocks 32 and the adjacent prefabricated blocks. The adhesive strip 55 thus covers the upper secondary anchor strips 102 and the secondary waterproofing membrane 2.

[0117] The primary end blocks 52 comprise a top wall 522 (or lid wall) and a side wall 521. The side wall 521 is aligned with the first height 61 and third height 81 in the thickness direction of the tank wall 100. Thus, the primary end blocks 52 terminate the tank wall 100 at the primary layer.

[0118] As illustrated in [Fig.6], the second metal structure 9 covers the primary end blocks 52 and part of the third height 81.

[0119] The second metal structure 9 comprises a second base 92 and a second height 91. The second base 92 and the second height 91 form a right angle with respect to each other at the upper end of the primary end blocks 52 of the row of primary end blocks 52. Thus, in the transverse direction, the second height 91 and the second base 92 form an inverted "L" of 180°.

[0120] On the one hand, the second base 92 is fixed to the primary anchor strips 202. On the other hand, the second height 91 is fixed to the third height 81 in a watertight manner by continuous welding.

[0121] As illustrated in [Fig.7], the primary sealing membrane 4 comprises a plurality of corrugations 43 extending in the longitudinal direction L and flat parts 44 situated between the corrugations 43.

[0122] The flat parts 44 are fixed in a sealed manner to the third base 92.

[0123] The undulations 43 and the third base 92 delimit orifices 45 at the ends longitudinal undulations 43.

[0124] Furthermore, the primary sealing membrane 4 comprises a plurality of caps 40 at the longitudinal ends of the corrugations 43. The caps 40 comprise only a cap body 41 ([Fig. 8]). The cap body 41 conforms to the contour of the corrugation 43.

[0125] The caps 40 seal the orifices 45 tightly. Thus, the primary sealing membrane 4 and the second metal structure 9 effectively enclose the primary insulating barrier 5 of the tank wall 100 in a hermetic manner.

[0126] As illustrated in [Fig.8], the caps 40 are fixed by welding to the longitudinal ends of the corrugations 43 and to the third 92: the cap body 41 is fixed in a sealed manner to the longitudinal ends of the longitudinal corrugations.

[0127] Alternatively, the caps 40 comprise a cap body 41 and a cap foot 42 ([Fig.9]). The cap foot 41 has a generally rectangular shape and extends from the cap body 41 such that the cap body 41 and the cap foot 42 form a right angle.

[0128] Furthermore, the width 1 of the cap foot 42 corresponds to 1 / 5 of the height h of the cap body 4L. However, a ratio of the width 1 of the cap foot 42 to the height h of the cap body 41 can vary between 1 and 1 / 6.

[0129] In this case, the cap foot 42 is welded to the third base 92 by a lap weld. The cap foot 42 facilitates the positioning of the cap and therefore the welding of the cap 42 onto the second base 92 and also the welding with the corrugation 43 by an operator.

[0130] Thus, in this embodiment, the sealing structure comprises the first metal structure 6, the second metal structure 9 and the third metal structure 8. The third metal structure 8 connects the first metal structure 6 and the second metal structure 9 in a watertight manner.

[0131] As illustrated in figures 6 and 7, in the direction of the thickness of the tank wall 100, the sealing structure comprises the first height 61, the second height 91 and the third height 81.

[0132] The load-bearing wall 1000, the first metal structure 6, the third metal structure 8, and the secondary sealing membrane 2 define a first sealed enclosed space containing the secondary insulating barrier. It is then possible to check the airtightness of this sealed enclosed space.

[0133] Similarly, the secondary sealing membrane 2, the third metal structure 8, the second metal structure 9, the primary sealing membrane, and the caps 40 define a second sealed enclosed space containing the primary insulating barrier. It is then possible to check the seal of this sealed enclosed space.

[0134] The interrupted tank wall in the longitudinal direction L has just been described. The interrupted tank wall in the transverse direction T has the same characteristics mutatis mutandis.

[0135] Manufacturing process

[0136] Figures 1 to 9 illustrate the successive manufacturing steps that lead to a sealed tank as described above.

[0137] As illustrated in [Fig.1], the prefabricated blocks are first anchored in the load-bearing wall 1000.

[0138] The secondary end boxes 32 are then anchored in the load-bearing wall 1000 and the lateral anchor strips 101 and the upper secondary anchor strips 102 are fixed on the secondary end boxes 32.

[0139] As illustrated in [Fig.1], a first thermal protection sheet 601 is positioned on the second side wall 321 and then the first metal structure 6 is fixed to the load-bearing wall 1000 and to the lateral anchor strips 101 of the row of secondary end boxes 32.

[0140] Then, as illustrated in [Fig. 2], a thermal protection sheet 801 is positioned on the upper edge of the secondary end boxes 32 and the third metal structure 8 is fixed to upper secondary anchor bands 102 and to the first height 61.

[0141] Then, as illustrated in [Fig.4], an adhesive strip 55 is fixed on either side of the row of secondary end blocks 32 and the adjacent prefabricated blocks.

[0142] Then, as illustrated in [Fig.5], the primary end boxes 52 are fixed to the tank wall using the adhesive strip 55.

[0143] Then, as illustrated in [Fig.6], the second structure 9 is fixed to the primary anchor strips 202 and to the third height 82.

[0144] Then, as illustrated in figures 7 and 8, the sealing membrane 4 is fixed to the second structure 9 and the caps 40 are fixed to the longitudinal ends of the corrugations 43 to close the orifices 45.

[0145] The technique described above for constructing a tank with two watertight membranes can be used in various types of tanks, for example, to construct a double-membrane tank for liquefied natural gas (LNG) in an onshore installation or in a floating structure such as an LNG carrier or other vessel. It can also be used to construct a tank wall with a single watertight membrane. In this context, the secondary sealing membrane 2, the secondary thermally insulating barrier 3, and the third metal structure 8 illustrated in the preceding figures can be considered to be eliminated, and the second height 91 is welded watertight to the first height 61.Thus, the load-bearing wall 1000, the first metal structure 6, the second metal structure 9, the single sealing membrane and the caps 40 delimit a sealed, enclosed space containing a single insulating barrier and whose sealing can be controlled.

[0146] In this way, this technique can also be applied to tanks having one or more thermally insulating barriers and one or more superimposed waterproof membranes.

[0147] With reference to [Fig. 10], a cutaway view of an LNG carrier 70 shows a sealed and insulated tank 71 of generally prismatic shape mounted in the double hull 72 of the vessel. The wall of the tank 71 comprises a primary watertight barrier intended to be in contact with the LNG contained in the tank, a secondary watertight barrier arranged between the primary watertight barrier and the double hull 72 of the vessel, and two insulating barriers arranged respectively between the primary watertight barrier and the secondary watertight barrier and between the secondary watertight barrier and the double hull 72.

[0148] In a manner known per se, loading / unloading pipelines 73 arranged on the upper deck of the ship can be connected, by means of appropriate connectors, to a marine or port terminal or to an LNG bunkering vessel to transfer an LNG cargo to or from tank 71.

[0149] Figure 10 shows an example of a marine terminal comprising a loading and unloading berth 75, a subsea pipeline 76 and an onshore facility 77. The loading and unloading berth 75 is a fixed offshore facility comprising a movable arm 74 and a tower 78 which supports the movable arm 74. The movable arm 74 carries a bundle of insulated flexible pipes 79 which can be connected to the loading / unloading pipelines 73. The steerable movable arm 74 is suitable for all LNG carrier sizes. An unshown connecting pipeline extends inside tower 78. The loading and unloading station 75 allows the loading and unloading of the LNG carrier 70 from or to the onshore facility 77. This facility includes liquefied gas storage tanks 80 and connecting pipelines 810 linked by the subsea pipeline 76 to the loading or unloading station 75.The subsea pipeline 76 allows the transfer of liquefied gas between the loading or unloading station 75 and the onshore facility 77 over a long distance, for example 5 km, which allows the LNG carrier 70 to be kept a long distance from the coast during loading and unloading operations.

[0150] To generate the pressure necessary for the transfer of the liquefied gas, pumps on board the ship 70 and / or pumps equipping the land installation 77 and / or pumps equipping the loading and unloading station 75 are used.

[0151] Although the invention has been described in connection with several particular embodiments, it is clearly evident that it is by no means limited to them and that it includes all technical equivalents of the means described as well as their combinations if these fall within the scope of the invention.

[0152] The use of the verb "comprise", "comprendre" or "include" and its conjugated forms does not exclude the presence of other elements or steps than those stated in a claim.

[0153] In the claims, any reference sign in parentheses shall not be interpreted as a limitation of the claim.

Claims

1. Demands A sealed and thermally insulating tank for the storage of a liquefied gas, the tank comprising a tank wall (100) resting against a load-bearing wall (1000), the tank wall comprising at least one sealing membrane and at least one thermally insulating barrier arranged between the sealing membrane and the load-bearing wall, the thermally insulating barrier comprising a row of end blocks (32) extending in a transverse direction (T);the tank wall further comprising a sealing structure extending between the sealing membrane (4) and the load-bearing wall in a thickness direction of the tank wall so as to hermetically enclose at least one space between the sealing membrane and the load-bearing wall, the sealing structure extending along the end blocks (32) and terminating the tank wall in a longitudinal direction (L) perpendicular to the transverse direction, the sealing structure being hermetically fixed on one side to the load-bearing wall and, on the other side, to the sealing membrane; the sealing structure comprising a first metal structure (6) and a second metal structure (9); the first metal structure comprising a first height (61) and a first base (62); the first base (62) being hermetically fixed to the load-bearing wall; the first height (61) extending along the thickness direction of the tank wall;the second metal structure comprising a second height (91) extending along the thickness direction of the tank wall and a second base (92), the second base (92) covering and being fixed to an upper wall of the end blocks; the sealing membrane comprising a plurality of corrugations (43) extending in the longitudinal direction (L) and flat parts (44) situated between the corrugations, the flat parts (44) of the sealing membrane being fixed in a watertight manner to the second base (92); the sealing membrane further comprising a plurality of caps (40) fixed in a watertight manner to longitudinal ends of the longitudinal corrugations and to the second base (92) to close said longitudinal ends.

2. A sealed and thermally insulating tank according to claim 1, wherein at least one said cap comprises a cap foot (42) and a cap body (41), the cap foot being hermetically fixed to the second base, the cap body being hermetically fixed to the longitudinal end of said longitudinal corrugation.

3. A sealed and thermally insulating tank according to claim 2, wherein the cap foot has a generally flat shape, the cap foot and the cap body forming an angle with respect to each other of between 80° and 100°, for example 90°.

4. A watertight and thermally insulating tank according to any one of claims 2 to 3 in which the cap foot is fixed to the second base by a lap weld.

5. A watertight and thermally insulating tank according to any one of the preceding claims in which said end block comprises a plurality of lateral anchoring strips (101), the lateral anchoring strips being fixed to a lateral wall of said end block; the first height (61) being fixed to the lateral anchoring strips.

6. A watertight and thermally insulating tank according to claim 5, in which the first height (61) is fixed to the lateral anchoring strips by spot welding.

7. A watertight and thermally insulating tank according to any one of the preceding claims in which said end block comprises a plurality of anchoring strips (202); the anchoring strips (202) being fixed to an upper wall (512) of said end block; the second base being fixed to the anchoring strips in a watertight manner.

8. A sealed and thermally insulating tank according to any one of the preceding claims in which a first thermal protection sheet (601) is positioned on one of the side walls (321) of an end block; the first thermal protection sheet being covered by the first height (61).

9. A watertight and thermally insulating tank according to any one of the preceding claims, wherein the sealing membrane is a primary sealing membrane (4), the barrier thermally insulating is a primary thermally insulating barrier (5) and the row of end blocks is a row of primary end blocks (52); the tank wall further comprising a secondary sealing membrane (2) arranged between the primary thermally insulating barrier and the load-bearing wall and a secondary thermally insulating barrier (3) arranged between the load-bearing wall and the secondary sealing membrane, the secondary thermally insulating barrier comprising a row of secondary end blocks (32);the sealing structure further comprises a third metal structure (8) arranged between the first metal structure (6) and the second metal structure (9), the third metal structure comprising a third height (81) and a third base (82), the third base (82) being fixed to an upper wall of the secondary end blocks, the third height (81) being fixed in a watertight manner to the first height (61), the second height (91) being fixed in a watertight manner to the third height (81).

10. A watertight and thermally insulating tank according to claim 9, in which the second height (91) is fixed in a watertight manner to the third height (81) by continuous welding.

11. A watertight and thermally insulating tank according to claim 9 or 10, wherein the third height (81) is fixed in a watertight manner to the first height (61) by a continuous weld.

12. A watertight and thermally insulating tank according to any one of claims 9 to 11, wherein a said end secondary block (32) comprises a plurality of upper secondary anchoring strips (102); the upper secondary anchoring strips being fixed to an upper wall (322) of said end secondary block; the second base (82) being fixed to the upper secondary anchoring strips.

13. A watertight and thermally insulating tank according to claim 12, in which the second base (82) is fixed to the upper secondary anchoring strips by spot welding.

14. A watertight and thermally insulating tank according to any one of claims 9 to 13, wherein a second sheet of thermal protection (801) is positioned on one side on an upper wall (322) of said secondary end block and on the other side on a lateral wall (321) of said secondary end block; the second thermal protection sheet being covered by the third height (81) and the third base (82).

15. A watertight and thermally insulating tank according to any one of claims 9 to 14, wherein the secondary sealing membrane is made of composite material.

16. A sealed and thermally insulating tank according to any one of the preceding claims, wherein the undulations extend periodically along the transverse direction of the tank wall.

17. A sealed and thermally insulating tank according to any one of the preceding claims in which the load-bearing wall has an opening, the tank wall being terminated by the sealing structure near the opening.

18. A method for testing the tightness of the sealing membrane in a sealed and thermally insulated tank according to any one of claims 1 to 17; the method comprising: - depressurizing the insulating barrier with respect to an environment external to the tank wall; and - measuring a parameter representative of the evolution of the pressure inside the insulating barrier after depressurizing the tank wall.

19. Vessel (70) for the transport of a cold liquid product, the vessel comprising a double hull (72) and a watertight and thermally insulating tank according to any one of claims 1 to 18 disposed in the double hull.

20. Transfer system for a cold liquid product, the system comprising a vessel (70) according to claim 19, insulated pipes (73, 79, 76, 810) arranged to connect the vessel's tank (71) to a floating or land-based storage facility (77) and a pump to drive a flow of cold liquid product through the insulated pipes from or to the floating or land-based storage facility to or from the vessel's tank.

21. A method for loading or unloading a vessel (70) according to claim 19, wherein a cold liquid product is conveyed through insulated pipes (73, 79, 76, 810) from or to a floating or land-based storage installation (77) to or from the ship's tank.

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