Manufacturing process for producing a sealing membrane for a leak-proof and thermally insulating liquefied gas storage tank

Abstract

A manufacturing process is described for producing a sealing membrane for a leak-proof and thermally insulating liquefied gas storage tank. A first metal sheet (44) and a second metal sheet (44) are arranged, the second metal sheet (44) overlapping the first metal sheet (44) in an overlap zone (ZR), and an inerting device (200, 300) comprising an inflatable balloon (220, 320) are used. The inflatable balloon (220, 320) is inflated to close an inerting space (235, 335) around a central portion (225, 325) of the inflatable balloon (220, 320), the inerting space (235, 335) being located directly above at least a portion of the overlap zone (ZR).After placing the closed inerting space (235, 335) under an inert atmosphere, a continuous weld is made between the second metal sheet (44) and the first metal sheet (44) along the overlap zone (ZR), the continuous weld passing directly over the inerting space (235, 335). Figure for the abbreviation: Fig. 6.

Description

Title of the invention: Manufacturing process for producing a sealing membrane for a sealed and thermally insulating tank for storing a liquefied gas technical field

[0001] The invention relates to the field of sealed and thermally insulated membrane tanks. In particular, the invention relates to the field of sealed and thermally insulated tanks for the storage and / or transport of liquefied gases, such as liquid hydrogen, which is at approximately -253°C at atmospheric pressure. Technological background

[0002] In the prior art, sealed and thermally insulated tanks for storing a liquefied gas, such as liquefied natural gas (LNG) or liquid hydrogen, are known.

[0003] Document WO 2023 / 198637 Al discloses a tank in which the walls have a multilayer structure, that is to say, they successively have, in the direction of wall thickness, from the outside to the inside, a secondary thermally insulating barrier retained to the load-bearing structure, a secondary sealing membrane resting against the secondary thermally insulating barrier, a primary thermally insulating barrier resting against the secondary sealing membrane and a primary sealing membrane intended to be in contact with the liquefied gas contained in the tank.

[0004] The primary thermally insulating barrier comprises rows of load-bearing elements, each of the load-bearing elements being fixed to an external plate and an internal plate, the external plates being fixed to the secondary thermally insulating barrier and pressing the secondary sealing membrane against the secondary thermally insulating barrier, the internal plates forming a support surface for the primary sealing membrane.

[0005] The primary sealing membrane comprises a plurality of corrugated metal sheets, the edges of which are welded to the internal trays, and which are welded with overlap along their edges to ensure the sealing of the primary sealing membrane.

[0006] Such a tank is suitable for storing liquid hydrogen at -253°C at atmospheric pressure.

[0007] However, when the tank is filled with liquid hydrogen at -253°C and atmospheric pressure, the primary sealing membrane is subjected to very high thermal stresses. It is therefore important to ensure its mechanical strength. of the primary waterproofing membrane.

[0008] Furthermore, to give the primary thermally insulating barrier the required thermally insulating properties, the primary thermally insulating barrier has a gaseous phase which is placed at a very low absolute pressure. It is important that this vacuum is not degraded by the primary sealing membrane. Summary

[0009] Among the factors that affect the mechanical strength of the primary sealing membrane and its impact on the vacuuming of the primary thermally insulating barrier is the presence of residual porosity in the welds between the corrugated metal sheets of the primary sealing membrane. If the welding operation causes excessive melting of the metal alloy of the corrugated metal sheets, the welds between the corrugated metal sheets are likely to exhibit high residual porosity. This risk is greater when the welding operation is not carried out under an inert atmosphere, because the metal alloy is then susceptible to hot oxidation due to the high temperature and the presence of oxygen in the atmosphere.The higher the residual porosity of the welds between the corrugated metal sheets, the more surface irregularities they exhibit, which can generate crack initiations that are detrimental to the mechanical strength of the primary waterproofing membrane, and the more likely they are to degrade the performance of the vacuum sealing of the primary thermally insulating barrier.

[0010] One idea underlying the invention is to propose a method for manufacturing a sealing membrane which tends to limit residual porosity in the welds between corrugated metal sheets.

[0011] According to one embodiment, the invention provides a manufacturing process for manufacturing a sealing membrane for a sealed and thermally insulating tank for storing a liquefied gas, the manufacturing process comprising the following steps: - to arrange an inerting device, a first metal sheet and a second metal sheet on a flat support surface, the first metal sheet and the second metal sheet each having two flat portions resting on the flat support surface and a corrugated portion formed between the two flat portions, the corrugated portion being projecting relative to the two flat portions, with the corrugated portion of the first metal sheet and the corrugated portion of the second metal sheet aligned, the second metal sheet covering the first metal sheet in an overlap zone defined between an edge of the first metal sheet and an edge of the a second metal sheet parallel to the edge of the first metal sheet, the corrugated portion of the first metal sheet extending to said edge of the first metal sheet and the corrugated portion of the second metal sheet extending to said edge of the second metal sheet, one end of the corrugated portion of the second metal sheet covering one end of the corrugated portion of the first metal sheet in the overlap zone and the two flat portions of the second metal sheet covering the two flat portions of the first metal sheet in the overlap zone, the first metal sheet being located between the second metal sheet and the support surface in the overlap zone, the inerting device comprising a gas supply line and an inflatable balloon, the inflatable balloon having a central portion and two flanges on either side of the central portion, the gas supply line being configured to convey gas into an inerting space located between the two flanges and around the central portion; - inflate the inflatable balloon until the two flanges are compressed against the inner contour of the corrugated portion of the first metal sheet, so as to close the inerting space, the inerting space being located at the right of at least part of the overlap area; - place the closed inerting space under an inert atmosphere by supplying an inert gas via the supply line; - to perform a continuous weld between the second metal sheet and the first metal sheet along the overlap area while the inerting space is under an inert atmosphere, the continuous weld passing over the inerting space.

[0012] Since continuous welding is performed while the inerting chamber is under an inert atmosphere, hot oxidation of the metal alloy of the first metal sheet is avoided. This, in turn, prevents the weld between the second and first metal sheets from exhibiting high residual porosity after the recrystallization of the metal alloy. Thus, thanks to the inerting device, the sealing membrane exhibits improved mechanical strength and reduces degradation of the vacuum barrier beneath the sealing membrane.

[0013] According to embodiments, such a manufacturing process may include one or more of the following characteristics.

[0014] According to one embodiment, the inert gas is dinitrogen or argon.

[0015] According to one embodiment, the gas supply line is configured to conveying the inert gas into the inflatable balloon, at least part of an outer wall of the central portion being impermeable to the inert gas below an inflation pressure threshold and permeable to the inert gas above the pressure threshold of inflation, and the inflatable balloon is inflated to at least the inflation pressure threshold by the inert gas, so that the inerting space is put under an inert atmosphere by inert gas passing through said outer wall.

[0016] The inerting device, or at least the inflatable balloon, may optionally be left in place after the continuous weld has been performed. However, from an economic and industrial standpoint, it is preferable to use the inerting device to successively perform several continuous welds between corrugated metal sheets. Thus, according to one embodiment, the manufacturing process further includes a step of removing the inerting device, the step of removing the inerting device comprising deflating the inflatable balloon and then sliding the inflatable balloon into the corrugation portion of one of the metal sheets, preferably the second metal sheet.

[0017] According to one embodiment, said one among the first metal sheet and the second metal sheet comprises first parallel corrugations, second corrugations perpendicular to the first corrugations, and a plurality of nodes at the intersections of said first corrugations and second corrugations, said corrugation portion of said one among the first metal sheet and the second metal sheet is a portion of said first corrugation, said corrugation portion comprises between the edge and a said node a concave portion forming a narrowing of said first corrugation, and the step of removing the inerting device comprises tilting the inflatable balloon between the edge and the narrowing after deflating the inflatable balloon.

[0018] Tilting the inflatable balloon makes it easy to pass through the narrowing of the inflatable balloon.

[0019] According to one embodiment, the second metal sheet has a welt along said edge of the second metal sheet.

[0020] According to one embodiment, the step of making a continuous weld between the second metal sheet and the first metal sheet along the overlap area is carried out by an automatic welding machine, the automatic welding machine moving parallel to said edges of the first metal sheet and the second metal sheet.

[0021] According to one embodiment, the support surface is an internal surface of a thermally insulating barrier.

[0022] According to one embodiment, the sealing membrane is a primary sealing membrane, the thermally insulating barrier is a primary thermally insulating barrier, and wherein the tank wall further comprises a secondary sealing membrane and a secondary thermally insulating barrier, the secondary thermally insulating barrier resting against a load-bearing wall, the secondary sealing membrane resting against the secondary thermal insulating barrier, and the primary thermal insulating barrier resting against the secondary sealing membrane.

[0023] According to one embodiment, the primary thermally insulating barrier comprises rows of load-bearing elements, each of the load-bearing elements being fixed to an external plate and to an internal plate, the external plates being fixed to the secondary thermally insulating barrier and pressing the secondary sealing membrane against the secondary thermally insulating barrier, the internal plates forming said support surface, and arranging the first metal sheet and the second metal sheet on the support surface comprises welding the first metal sheet and the second metal sheet to said internal plates.

[0024] According to one embodiment, placing the inerting device on the support surface includes routing the gas supply line through gaps provided between the internal plates.

[0025] According to another embodiment, the secondary thermally insulating barrier comprises a plurality of secondary insulating blocks juxtaposed on the load-bearing wall, the primary thermally insulating barrier comprises a plurality of primary insulating blocks juxtaposed on the secondary sealing membrane and anchored to the secondary thermally insulating barrier by anchoring members carried by the secondary insulating blocks, the primary insulating blocks having anchoring plates, and arranging the first metal sheet and the second metal sheet on the support surface comprises welding the first metal sheet and the second metal sheet to said anchoring plates.

[0026] According to one embodiment, the invention also provides a sealed and thermally insulating tank comprising a sealing membrane manufactured by the manufacturing process according to any one of the embodiments described above.

[0027] In one embodiment, the liquefied gas is liquid hydrogen.

[0028] Such a tank may be part of a land-based storage facility or installed in a floating structure, whether coastal or deep-water, including a liquid hydrogen transport vessel, i.e., a hydrogenerator, a floating storage and regasification unit (FSRU), a floating production and remote storage unit (FPSO), and others. Such a tank may also serve as a fuel tank in any type of vessel.

[0029] According to one embodiment, a ship for the transport of a liquefied gas comprises a double hull and the aforementioned tank disposed in the double hull.

[0030] According to one embodiment, the invention also provides a transfer system for a liquefied gas, the system comprising the aforementioned vessel and insulated pipelines arranged to connect the tank installed in the hull of the vessel to an installation floating or land-based storage.

[0031] According to one embodiment, the transfer system also includes a pump for driving a flow of liquefied gas through insulated pipes from or to the floating or land-based storage facility to or from the ship's tank.

[0032] According to one embodiment, the invention also provides a method for loading or unloading such a vessel, in which a liquefied gas is conveyed through insulated pipelines from or to a floating or land-based storage facility to or from the vessel's tank. Brief description of the figures

[0033] 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.

[0034] [Fig-1] The [Fig. 1] is a partial perspective view of a tank wall of a sealed and thermally insulating tank.

[0035] [Fig.2] Fig.2 is a perspective view of an alternative embodiment of a inerting device.

[0036] [Fig.3] The [Fig.3] is a partial perspective view, showing the arrangement of the inerting device of the [Fig.2] and of a corrugated metal sheet on the primary thermally insulating barrier of the tank wall of the [Fig.1].

[0037] [Fig.4] Fig.4 is a perspective and partial sectional view of detail IV of the [Fig.3],

[0038] [Fig.5] The [Fig.5] is a perspective and partial sectional view, showing the arrangement of another corrugated metal sheet covering the corrugated metal sheet of the [Fig.3] in an overlap area.

[0039] [Fig.6] The [Fig.6] is a cross-sectional view along a plane cutting the overlap area visible on the [Fig.5].

[0040] [Fig.7] The [Fig.7] is a side view along arrow DI on the [Fig.5].

[0041] [Fig.8] [Fig.8] is a sectional view along the same cutting plane as [Fig.6], illustrating a step in removing the inerting device.

[0042] [Fig.9] Fig.9 is another side view along arrow DI in Fig.5, illustrating the step of removing the inerting device.

[0043] [Fig. 10] The [Fig. 10] is a perspective view analogous to the [Fig.2], showing another variant embodiment of the inerting device.

[0044] [Fig. 11] [Fig. 11] is a partial perspective view similar to [Fig. 3], showing the arrangement of the inerting device of [Fig. 10] and a corrugated metal sheet on the primary thermally insulating barrier of the tank wall of the [Fig.l].

[0045] [Fig.12] The [Fig.12] is a side view along arrow D2 on the [Fig.11], illustrating the step of removing the inerting device.

[0046] [Fig. 13] The [Fig. 13] is a schematic cutaway representation of a ship tank and a loading / unloading terminal for this tank. Description of the implementation methods

[0047] By convention, the terms "external" and "internal" are used to define the relative position of one element with respect to another, by reference to the inside and outside of the tank.

[0048] Figure 1 shows a partial perspective view of a tank wall 11 of a sealed and thermally insulated liquefied gas storage tank. The wall 11 shown is constructed in accordance with the teachings of document WO 2023 / 198637 AL

[0049] As described in document WO 2023 / 198637 A1, the wall 11 is fixed against a load-bearing wall forming part of a load-bearing structure 1, for example, a polyhedral structure. The load-bearing structure 1 is, for example, formed by the double hull of a ship. The wall 11 has a multilayer structure comprising, along the thickness direction of the wall 11, from the outside in, a secondary thermally insulating barrier 12, a secondary sealing membrane 13, a primary thermally insulating barrier 14, and a primary sealing membrane 15 intended to be in contact with the liquefied gas contained in the tank.

[0050] The secondary thermally insulating barrier 12 comprises a plurality of insulating panels 16 anchored to the load-bearing structure 1. Each insulating panel 16 comprises a layer of insulating polymer foam 17 sandwiched between an inner plate 18 and an outer plate 19. The inner plate 18 and outer plate 19 are, for example, plywood panels bonded to said layer of insulating polymer foam 17. In one embodiment, the inner plate 18 and outer plate 19 are made of a fiber-reinforced polymer matrix, such as glass fibers. The insulating polymer foam may, in particular, be a polyurethane-based foam. The polymer foam is advantageously reinforced with fibers, such as glass fibers, which helps to reduce its thermal contraction.

[0051] The insulating panels 16 each comprise a layer of insulating polymer foam 17 sandwiched between an inner plate 18 and an outer plate 19. The inner plate 18 and outer plate 19 are, for example, plywood panels bonded to said layer of insulating polymer foam 17. In one embodiment, the inner plate 18 and outer plate 19 are made of a fiber-reinforced polymer matrix, such as glass fibers. The insulating polymer foam may, in particular, be a polyurethane-based foam. The polymer foam is advantageously, reinforced with fibers, such as glass fibers, helping to reduce its thermal contraction.

[0052] Advantageously, portions of sealant 20 are interposed between the outer plate 19 of the insulating panels 16 and the supporting structure 1. The portions of sealant 20 thus contribute to compensating for surface irregularities of the supporting structure 1. According to an advantageous embodiment, the portions of sealant 20 adhere to the outer plate 19 of the insulating panels 16 and to the supporting structure 1. The portions of sealant 20 thus contribute to anchoring the insulating panels 16 to the supporting structure 1. In such an embodiment, the secondary anchoring devices are optional.

[0053] The insulating panels 16 are substantially rectangular in shape and are placed side by side in parallel rows, separated from each other by gaps 21 ensuring a functional mounting clearance. The gaps 21 are filled with thermal insulation, not shown, such as glass wool, rock wool, or flexible open-cell polymer foam, for example. The gaps can also be filled with insulating plugs, such as those described in applications WO2019155157 or WO2021028624, for example.

[0054] In the embodiment shown, the inner face of the insulating panels 16 has two sets of grooves 22 perpendicular to each other and designed to receive corrugations 24, projecting outwards from the tank, formed on the corrugated metal sheets 25 of the secondary sealing membrane 13. Each set of grooves 22 is parallel to two opposite sides of the insulating panels 16. In the embodiment shown, the grooves 22 pass completely through the thickness of the inner plate 10 as well as through an inner portion of the insulating polymer foam layer 17. Advantageously, the grooves 22 have a shape complementary to that of the corrugations in the secondary sealing membrane 13.

[0055] Furthermore, the insulating panels 16 have relaxation slots 27 which reduce their stiffness so that the secondary thermally insulating barrier 12 deforms as homogeneously as possible. This results in the most uniform deformations possible of the corrugations in the secondary sealing membrane 13. Advantageously, the insulating panels 16 have relaxation slots 27 at least opposite each of the corrugations in the secondary sealing membrane 13. Further details on the thermally insulating barrier 12 and the secondary sealing membrane 13 can be found in document WO 2023 / 198637 AL

[0056] The primary thermally insulating barrier 14 comprises a plurality of load-bearing elements 30 extending along the thickness direction of the wall 11. The load-bearing elements 30 support the primary sealing membrane 15 and, by Consequently, to absorb the stresses due to hydrostatic and dynamic pressures exerted on the primary sealing membrane 15 by the liquefied gas contained inside the tank. The load-bearing elements 30 are aligned in parallel rows.

[0057] Further details on the load-bearing elements 30 can be found in document WO 2023 / 198637 A1. In particular, as described in that document, the load-bearing elements 30 are each fixed to an external plate attached to the secondary thermally insulating barrier 12 and pressing the secondary sealing membrane 13 against the secondary thermally insulating barrier 12, and to an internal plate 42 (not shown in [Fig.1] but shown in [Fig.4]).

[0058] The primary sealing membrane 15 is obtained by assembling a plurality of corrugated metal sheets 44. Each of the corrugated metal sheets 44 has a substantially rectangular shape. The corrugated metal sheets 44 are, for example, made of Invar®: that is, an iron and nickel alloy whose coefficient of thermal expansion is typically between 1.2 x 10⁶ and 2 x 10⁶ K⁻¹, or of a high-manganese iron alloy whose coefficient of thermal expansion is typically around 7 x 10⁶ K⁻¹. Alternatively, the corrugated metal sheets 44 can also be made of stainless steel or aluminum.

[0059] The corrugated metal sheets 44 are welded overlapping along their edges to ensure the sealing of the primary sealing membrane 15. The primary sealing membrane 15 has corrugations 45. More particularly, it has a first series of corrugations 45a extending parallel to a first direction and a second series of corrugations 45b extending parallel to a second direction. The directions of the series of corrugations 45a, 45b are perpendicular and are parallel or perpendicular to the rows of load-bearing elements 30. Each of the series of corrugations 45a, 45b is parallel to two opposite edges of the corrugated metal sheets 44. The corrugations 45 protrude towards the inside of the tank, i.e. in the opposite direction to the load-bearing structure 1. Each corrugated metal sheet 44 has between the corrugations 45, a plurality of flat areas 46.

[0060] The pitch of the corrugations in the secondary waterproofing membrane 13 is equal to the pitch of the corrugations 45 in the primary waterproofing membrane 15 or to an integer multiple thereof. Furthermore, each corrugation in the secondary waterproofing membrane 13 is arranged opposite, along the thickness direction of the wall 11, a corrugation 45 in the primary waterproofing membrane 15. Thus, each flat area 46 in the primary waterproofing membrane 15 is located opposite, along the thickness direction of the wall 11, a flat area in the secondary waterproofing membrane 13. Consequently, the axis of each load-bearing element 30 passes through both the center of a flat area 46 in the primary waterproofing membrane 15 and the center of a flat area in the membrane secondary sealing 13.

[0061] The corrugated metal sheets 44 of the primary sealing membrane 15 are at least anchored, by welding, along their edges to the internal plates 42. To do this, the edges of the corrugated metal sheets 44 are welded to the internal plates 42, for example by spot welds. According to an advantageous embodiment, the corrugated metal sheets 44 are also anchored to internal plates 42 outside their edge areas. To do this, the corrugated metal sheets 44 can, in particular, be welded to the internal plates 42 by through-welding. According to an advantageous embodiment, the corrugated metal sheets 44 are welded to each of the internal plates 42 that support them. Such an embodiment is particularly advantageous in that it allows for an even more uniform distribution of stresses between the corrugations 45 of the primary sealing membrane 15.

[0062] Further details on the primary thermally insulating barrier 14 can be found in document WO 2023 / 198637 A1. As described in this document, the wall 11 is suitable for constructing a sealed and thermally insulating tank for storing liquid hydrogen. Liquid hydrogen is a liquefied gas that is stored at approximately -253°C at atmospheric pressure. When the tank is filled with liquid hydrogen at -253°C at atmospheric pressure, the primary sealing membrane 15 is subjected to very high thermal stresses. It is therefore important to ensure the mechanical strength of the primary sealing membrane 15.

[0063] Furthermore, as described in document WO 2023 / 198637 A1, in order to impart the required thermally insulating properties to the primary thermally insulating barrier 14, the primary thermally insulating barrier 14 has a gaseous phase which is placed at an absolute pressure of less than 1 Pa, advantageously less than 10⁻¹ Pa, preferably less than 10² Pa, and for example, on the order of 10³ Pa. This absolute pressure can be obtained by means of a vacuum pump and / or by means of a cryopumping phenomenon. It is therefore important that this vacuum not be degraded by the primary sealing membrane 15.

[0064] As mentioned above, the corrugated metal sheets 44 are welded with overlaps along their edges to ensure the watertightness of the primary sealing membrane 15. During the welding operation, the metal alloy constituting the corrugated metal sheets 44 undergoes melting followed by recrystallization. If the welding operation causes excessive melting of the metal alloy, the welds between the corrugated metal sheets 44 may exhibit high residual porosity after the recrystallization of the metal alloy. This risk is greater when the welding operation is not carried out under an inert atmosphere. because the metal alloy is then susceptible to hot oxidation due to the high temperature and the presence of oxygen in the atmosphere. The higher the residual porosity of the welds between the corrugated metal sheets 44, the more surface irregularity they exhibit, which can generate crack initiation points that are detrimental to the mechanical strength of the primary sealing membrane 15, and the more likely they are to degrade the performance of the vacuuming of the primary thermally insulating barrier 14. The residual porosity will primarily increase the specific surface area of ​​the metal surfaces, thereby increasing the theoretical outgassing rate calculated from an underestimated nominal surface area.The performance of the vacuum sealing process can also be degraded by the creation of almost enclosed spaces, which contain a volume of gas that will be increasingly difficult to evacuate by pumping as the resistance to flow at the outlet of these spaces increases. Therefore, it is particularly desirable to limit the residual porosity resulting from the welding operation in the welds between the corrugated metal sheets 44.

[0065] Embodiments of a manufacturing process for the primary sealing membrane 15 which tend to limit this residual porosity are described below. This manufacturing process uses an inerting device, an alternative embodiment of which has been shown in perspective in [Fig.2].

[0066] With reference to [Fig. 2], the inerting device 200 comprises an inflatable balloon 220 and a gas supply line 290. The inflatable balloon 220 has two flanges 230. The flanges 230 are parallel and on either side of a central portion 225 of the inflatable balloon 220. In other words, the central portion 225 is positioned between the two flanges 230. The flanges 230 are deformable as will be detailed below.

[0067] In a first step of the manufacturing process, two corrugated metal sheets 44 (hereinafter "sheets 44") and inerting devices 200 are placed. This step is illustrated by figures 3 to 6.

[0068] In [Fig. 3], a sheet 44 has been partially and partially shown in perspective. As As mentioned above, the sheet 44 has flat portions 86 intended to rest on the internal plates 42. The sheet 44 has corrugated portions 85a, 85b projecting from the flat portions 86. Each corrugated portion 85a, 85b is formed between two flat portions 86. The corrugated portions 85a, 85b are intended to constitute, respectively, part of a corrugation 45a, 45b (see [Fig. 1]) of the primary sealing membrane 15. The reference symbols 56a each designate a junction between a flat portion 86 and a corrugated portion 85a. The reference symbols 56b each designate a junction between a flat portion 86 and a corrugated portion 85b. Nodes 55 are formed at the intersections between the undulation portions 85a, 85b. The nodes 55 have been omitted from [Fig.1] so as not to clutter the drawing.

[0069] The sheet 44 has a generally rectangular outer contour delimited by four straight edges 68 orthogonal to each other. Two of the four edges 68 are visible in [Fig. 3]. As shown, the corrugation portions 85a, 85b extend to the edges 68.

[0070] In the first step of the manufacturing process, a first sheet 44 is placed on internal trays 42, as shown in [Fig.3].

[0071] In addition, an inerting device 200 is placed in a portion of the corrugation 85a extending to a given edge 68. More precisely, the inflatable balloon 220 is placed in the portion of the corrugation 85a, near the edge 68, as can be seen more clearly in [Fig. 4]. As shown in [Fig. 3] and [Fig. 4], the gas supply line 290 leads to the inflatable balloon 220, preferably through gaps between adjacent internal plates 42.

[0072] Returning to [Fig.3], the sheet 44 is joggling (or joggled) along at least one other edge 68, so that the sheet 44 has a joggling (or joggled) 67 along said edge 68.

[0073] It can also be seen in [Fig. 3] that the internal trays 42 are provided with fastening elements 43. The fastening elements 43 are distributed around the axis of the carrier element 30 to attach a support flange 40 (see [Fig. 8]) of the carrier element 30 to the internal trays 42 as described in document WO 2023 / 198637 AL

[0074] With reference now to [Fig. 5] and [Fig. 6], the first plate 44 and the inerting device 200 having been positioned in this way, a second plate 44 (on the right and shown in partial section in [Fig. 5]) is positioned, the edge of which 67 overlaps the first plate 44 in an overlap zone ZR. With reference to [Fig. 6], the overlap zone ZR is defined between the edge 68 of the first plate 44 (on the left in [Fig. 6]) and the parallel edge 68 of the second plate 44 (on the right in [Fig. 6]). The dashed lines in [Fig. 6] indicate the position of the overlap zone ZR.As shown in Figures 5 and 6, the corrugation portions 85a of the first sheet 44 and the second sheet 44 are aligned; one end of the corrugation portion 85a of the second sheet 44 overlaps the end of the corrugation portion 85a of the first sheet 44 in the overlap zone ZR; and the flat portions 86 of the second sheet 44 on either side of the corrugation portion 85a overlap the flat portions 86 of the first sheet 44 on either side of the corrugation portion 85a in the overlap zone ZR.

[0075] It will be understood that when the first sheet 44 and the second sheet 44 are positioned in this way, their flat portions 86 rest on internal plates 42 (see [Fig. 3], [Fig. 4] and [Fig. 5]). These internal plates 42 form a support surface for the The first sheet 44 and the second sheet 44, and consequently a support surface for the primary sealing membrane 15. Before proceeding to the second step, the first sheet 44 and the second sheet 44 are anchored by welding, along their edges 68, to the internal trays 42 as mentioned above. For example, the first sheet 44 is welded to the internal trays 42 before the second sheet 44 is positioned to cover the first sheet 44 in the overlap zone ZR.

[0076] In a second step of the manufacturing process, the inflatable balloon 220 is inflated. The inflatable balloon 220 is shown in its deflated state in [Fig. 2], and in its inflated state in [Fig. 4] and [Fig. 6]. Since the flanges 230 are supported by the inflatable balloon 220 and are made of a deformable material, inflating the inflatable balloon 220 deforms the flanges 230 until they are compressed against the inner contour of the corrugated portion 85a of the first sheet 44. For this reason, the outer contour of the flanges 230 corresponds substantially to the inner contour of the corrugated portion 85a.

[0077] Reference numeral 235 designates an inerting space located between the two flanges 230 and around the central portion 225 of the inflatable balloon 220. As can be seen in [Fig.6], the inerting space 235 is located at the right of at least a part of the overlap zone ZR, at least when the inflatable balloon 220 is in its inflated state.

[0078] Thus, the inflation of the inflatable balloon 220 and the resulting compression of the flanges 230 against the inner contour of the corrugation portion 85a of the first sheet 44 close the inerting space 235, which is located at the right of at least part of the overlap zone ZR.

[0079] In a third step of the manufacturing process, the inerting space 235 thus closed is put under an inert atmosphere by supplying an inert gas via the gas supply line 290. For this, the gas supply line 290 is connected to a gas source 990 (represented schematically on [Fig.6]) which sends a flow of inert gas FG (see [Fig.6]) into the gas supply line 290. The inert gas can be dinitrogen (N2) or argon (Ar) for example.

[0080] It should be noted that the positioning of the gas supply line 290 relative to the inerting space 235 and the inflatable balloon 220 shown in the drawings is only one example. Various positions of the gas supply line 290 are possible.

[0081] According to one embodiment, the gas supply line 290 is connected to the inerting space 235, and the inflation of the inflatable balloon 220 is carried out by means of an inflation gas supply line separate from the gas supply line 290 and connected to the inflatable balloon 220. This makes it possible to inflate the inflatable balloon 220 with an inflation gas less expensive than the inert gas, for example with air, or with dinitrogen (N2) if the inert gas is argon (Ar).

[0082] According to another more preferred embodiment, the inert gas used to put the inerting space 235 under an inert atmosphere is also used for inflating the inflatable balloon 220. For this, at least a part of the outer wall of the central portion 225 which delimits the inerting space 235 is impermeable to the inert gas below an inflation pressure threshold and permeable to the inert gas above the inflation pressure threshold. The inert gas is conveyed through the gas supply line 290 into the inflatable balloon 220. The inflatable balloon 220 is inflated to at least the inflation pressure threshold, then the inert gas passes through the outer wall of the central portion 225, which has become permeable to the inert gas, and fills the inerting space 235. In this way, the risk of contamination of the inerting space 235 by an unwanted gas is reduced.

[0083] In a fourth step of the manufacturing process, a continuous weld is made between the first plate 44 and the second plate 44 along the overlap zone ZR while the inert gas space 235 is under an inert atmosphere, the continuous weld passing directly over the inert gas space 235. The continuous weld is performed using known welding techniques with a welding torch. For example, the welding torch is mounted on an automatic welding machine moving parallel to the edges 68 defining the overlap zone ZR. The arrow W in [Fig. 5] indicates the direction of travel of the automatic welding machine. The automatic welding machine can, for example, be constructed as described in document EP 0 611 217 AL. At the end of the fourth step, the second plate 44 is therefore welded with an overlap to the first plate 44 along the overlap zone ZR.

[0084] Various materials can be used to make the flanges 230 and the inflatable balloon 220, provided that inflating the inflatable balloon 220 deforms the flanges 230 until they are compressed against the inner contour of the corrugated portion 85a of the first sheet 44. The flanges 230 and the inflatable balloon 220 must have sufficient resistance to the heat generated by the welding torch. For example, the flanges 230 can be made of a polymer such as PTFE, PPSU, or PEEK. For example, the inflatable balloon 220 can be made of a polymer such as high-performance rubber or in the form of a multilayer structure comprising at least one polymer layer combined with a flexible woven composite skin.

[0085] Since continuous welding is performed while the inerting space 235 is under an inert atmosphere, hot oxidation of the metal alloy of the first sheet 44 is avoided, which in turn prevents the weld between the second sheet 44 and the first sheet 44 from exhibiting high residual porosity after the recrystallization of the metal alloy. Thus, thanks to the inerting device 200, the membrane primary sealing 15 has improved mechanical strength and degrades the vacuum sealing of the primary thermally insulating barrier 14 less.

[0086] The inerting device 200, or at least the inflatable balloon 220, may optionally be left in place after the continuous weld has been performed. However, from an economic and industrial point of view, it is preferable to use the inerting device 200 to perform several successive continuous welds between sheets 44.

[0087] For this purpose, in a fifth step of the manufacturing process, the supply of inert gas to the inerting space 235 is stopped, and the inflatable balloon 220 is removed from the cover zone ZR.

[0088] Figures 7 to 9 illustrate one possible way to remove the inflatable balloon 220.

[0089] With reference in particular to figures 5, 7, 8 and 9, on either side of vertex 55T From a node 55, constrictions 55R of the corrugation portions 85a are each formed by a concave portion of a corrugation portion 85a. The constriction 55R defines a minimal cross-section of the corrugation portion 85a. With reference to [Fig. 7], which is a side view along arrow DI in [Fig. 5] and shows the inflatable balloon 220 in its inflated state, due to the constriction 55R, it may be difficult to remove the inflatable balloon 220 if it remains inflated.

[0090] In order to remove the inflatable balloon 220, the inflatable balloon 220 is first deflated, that is to say, it is returned to its uninflated state as shown in [Fig. 2] and [Fig. 9]. The deflation of the inflatable balloon 220 can be initiated or assisted in various ways, for example by means of springs or other internal return elements within the inflatable balloon 220 and / or by connecting the inflatable balloon 220 to a vacuum pump.

[0091] In a second step, the inflatable balloon 220 having been deflated, the inflatable balloon 220 is tilted towards the adjacent node 55 of the second plate 44 (arrow M1 on the [Fig.8]), then the inflatable balloon 220 is slid into the corrugation portion 85a of the second plate 44 towards this node 55 (arrow M2 on the [Fig.8]). With reference to [Fig.8] and [Fig.9], tilting the inflatable balloon 220 allows it to easily pass through the constrictions 55R. The inflatable balloon 220 is then slid further into the corrugated sections 85a of the second plate 44 (arrow M3 in [Fig.8]), until it is extracted from under the second plate 44. The inflatable balloon 220 can then be reused to perform another weld between plates 44.The tilting and sliding of the inflatable balloon 220 can be caused by pulling on the gas supply line 290 and / or on a cable one end of which is attached to the inflatable balloon 220.

[0092] Alternatively, the tilting and sliding of the inflatable balloon 220 described above can take place in the corrugation portions 85a of the first plate 44 and not of the second plate 44 as shown in [Fig. 8]. However, it is preferable that the tilting and sliding of the inflatable balloon 220 take place in the corrugated portions 85a of the second plate 44, because in this case the gas supply line 290 can run under the second plate 44 towards the first plate 44 (cf. [Fig.3], [Fig.5]), which is easier than running the gas supply line 290 under the first plate 44.

[0093] The above-described steps of the manufacturing process are repeated as many times as necessary until the manufacturing of the primary sealing membrane 15 is completed.

[0094] As shown in [Fig.3] and [Fig.5], an inflatable balloon 220 is preferably used per portion of corrugation 85a of the first sheet 44.

[0095] Identical or analogous inerting devices to the inerting device 200 can be used for the undulation portions 85b. Figures 10 to 12 show, by way of example, an alternative embodiment of an inerting device 300 suitable for the undulation portions 85b. The elements of the inerting device 300, analogous to those of the inerting device 200, bear the same reference signs increased by 100. The operation of the inerting device 300 is identical to the operation of the inerting device 200, except that the dimensions of the inflatable balloon 320 and the outer contour of the flanges 330 are adapted to the inner contour of the corrugation portions 85b, so that inflating the inflatable balloon 320 closes the inerting space 325 in the corrugation portion 85b of the first plate 44.

[0096] As shown in [Fig. 11], an inflatable balloon 320 is preferably used per portion of corrugation 85b of the first sheet 44.

[0097] With reference to [Fig. 12], which is a side view along arrow D2 on [Fig. 11] and shows the inflatable balloon 320 in its uninflated state, the inflatable balloon 320 can be tilted towards the node 55 of the first plate 44, or preferably of the second plate 44, as described above for the inflatable balloon 220.

[0098] The dimensions of the inflatable balloons 220, 320 and the outer contour of the flanges 230, 330 are adapted respectively to the inner contour of the corrugation portions 85a, 85b. Alternatively, the same inerting device can be used for the corrugation portions 85a and the corrugation portions 85b.

[0099] Although not shown in the figures, the invention also applies in the case where an internal plate 42 is connected to another adjacent internal plate 42 by a connection that has one degree of freedom in translation along a direction perpendicular to the wall thickness direction and one degree of connection along the wall thickness direction. This allows the internal plates to which the flat portions 186 of the sealing membrane are attached to perform relative movements along the direction perpendicular to the wall thickness direction.

[0100] The manufacturing process has been described in the context of a sealed and thermo- uniquely insulating for the storage of liquefied hydrogen. Alternatively, the sealed and thermally insulating tank can be used to store other liquefied gases, including liquefied natural gas (LNG), liquefied petroleum gas (LPG), ethane, or ammonia.

[0101] The manufacturing process has been described in the context of a tank wall produced according to the teachings of document WO 2023 / 198637 AL. The manufacturing process is, however, also applicable to any other tank wall in which a sealing membrane is produced by overlapping welding of corrugated metal sheets, in particular to a tank wall in which the secondary thermally insulating barrier comprises a plurality of secondary insulating blocks placed side by side on the load-bearing wall, the primary thermally insulating barrier comprises a plurality of primary insulating blocks placed side by side on the secondary sealing membrane and anchored to the secondary thermally insulating barrier by anchoring elements carried by the secondary insulating blocks, the primary insulating blocks having anchoring plates. Such a tank wall can be produced according to the teachings of document FR 2 691 520 Al, document WO 2014 / 057221 A2 or document WO 2017 / 006044 Al for example. The sheets 44 are anchored by their edges to the anchor plates and not to the internal plates 42 described above.

[0102] With reference to [Fig. 13], a cutaway view of a vessel 70 shows a sealed and thermally insulating tank 71 of generally prismatic shape mounted in the double hull 72 of the vessel. The wall of the tank 71 comprises a primary sealing membrane intended to be in contact with the liquefied gas, preferably liquid hydrogen, contained in the tank, a secondary sealing membrane arranged between the primary sealing membrane and the double hull 72 of the vessel, and two thermally insulating barriers arranged respectively between the primary sealing membrane and the secondary sealing membrane and between the secondary sealing membrane and the double hull 72.

[0103] In a manner known per se, loading / unloading pipelines 73 arranged on the upper deck of the ship can be connected, by means of suitable connectors, to a marine or port terminal to transfer a cargo of liquefied gas from or to the tank 71.

[0104] Figure 13 also shows an example of a marine terminal comprising a loading and unloading berth 75, a subsea pipeline 76, and an onshore installation 77. The loading and unloading berth 75 is a fixed offshore installation comprising a movable arm 74 and a tower 78 that supports the movable arm 74. The movable arm 74 carries a bundle of insulated flexible pipes 79 that can be connected to the loading / unloading pipelines 73. The steerable movable arm 74 adapts to all hydrogenerator sizes. A non-returnable connecting pipeline The area shown extends inside the tower 78. The loading and unloading station 75 allows the loading and unloading of the hydrogenerator 70 to and from the onshore facility 77. The latter includes liquefied gas storage tanks 80 and connecting pipelines 81 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 makes it possible to keep the hydrogenerator vessel 70 a long way from the coast during loading and unloading operations.

[0105] To generate the pressure necessary for the transfer of the liquefied gas, one can either use pumps on board the ship 70 and / or pumps equipping the land installation 77 and / or pumps equipping the loading and unloading station 75 or allow a rise in pressure in the internal space of the tank under the effect of the evaporation of the liquefied gas stored in the tank.

[0106] 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.

[0107] 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.

[0108] In the claims, any reference sign in parentheses shall not be interpreted as a limitation of the claim.

Claims

Demands

1. A manufacturing method for producing a sealing membrane for a leak-proof and thermally insulating liquefied gas storage tank, the manufacturing method comprising the following steps: - placing an inerting device (200, 300), a first metal sheet (44) and a second metal sheet (44) on a flat support surface, the first metal sheet (44) and the second metal sheet each having two flat portions (86) resting on the flat support surface and a corrugated portion (85a, 85b) formed between the two flat portions (86), the corrugated portion (85a, 85b) being projecting from the two flat portions (86), the corrugated portion (85a, 85b) of the first metal sheet (44) and the corrugated portion (85a, 85b) of the second metal sheet (44) being aligned,the second metal sheet (44) overlapping the first metal sheet (44) in an overlap zone (ZR) defined between an edge (68) of the first metal sheet (44) and an edge (68) of the second metal sheet (44) parallel to the edge (68) of the first metal sheet (44), the corrugated portion (85a, 85b) of the first metal sheet (44) extending to said edge (68) of the first metal sheet (44) and the corrugated portion (85a, 85b) of the second metal sheet (44) extending to said edge (68) of the second metal sheet (44), one end of the corrugated portion (85a, 85b) of the second metal sheet (44) overlapping one end of the corrugated portion (85a, 85b) of the first metal sheet (44) in the overlap zone (ZR), and the two portions planes (86) of the second metal sheet (44) covering the two flat portions (86) of the first metal sheet (44) in the overlap zone (ZR),the first metal sheet (44) being located between the second metal sheet (44) and the support surface in the cover zone (ZR), the inerting device (200, 300) comprising a gas supply line (290, 390) and an inflatable balloon (220, 320), the inflatable balloon (220, 320) having a central portion (225, 325) and two flanges (230, 330) on either side of the central portion (225, 325), the gas supply line (290, 390) being configured to convey gas into an inerting space (235, 335) located between the two flanges (230, 330) and around the central portion (225, 325); - inflate the inflatable balloon (220, 320) until the two flanges (230, 330) are compressed against the inner contour of the corrugated portion (85a, 85b) of the first metal sheet (44), so as to close the inerting space (235, 335), the inerting space (235, 335) being located at the right of at least part of the overlap zone (ZR); - put the inerting space (235, 335) thus closed under an inert atmosphere by supplying an inert gas via the supply line (290, 390); - to carry out a continuous weld between the second metal sheet (44) and the first metal sheet (44) along the overlap zone (ZR) while the inerting space (235, 335) is under an inert atmosphere, the continuous weld passing over the inerting space (235, 335).

2. A manufacturing method according to claim 1, wherein the gas supply line (290, 390) is configured to convey the inert gas into the inflatable balloon (220, 320), at least a portion of an outer wall of the central portion (225, 325) being impermeable to the inert gas below an inflation pressure threshold and permeable to the inert gas above the inflation pressure threshold, and wherein the inflatable balloon (220, 320) is inflated to at least the inflation pressure threshold by the inert gas, so that the inerting space (235, 335) is placed under an inert atmosphere by inert gas passing through said outer wall.

3. A manufacturing method according to any one of claims 1 to 2, wherein the manufacturing method further comprises a step of removing the inerting device (200, 300), the step of removing the inerting device (200, 300) comprising deflating the inflatable balloon (220, 320) and then sliding the inflatable balloon into the corrugated portion (85a, 85b) of the second metal sheet (44).

4. A manufacturing method according to claim 3, wherein the second metal sheet (44) has first parallel corrugations, second corrugations perpendicular to the first corrugations, and a plurality of nodes (55) at the intersections of said first and second corrugations, said corrugation portion (85a) of the second metal sheet is a portion of said first corrugation, said corrugation portion (85a) has, between the edge (68) and said node (55), a concave portion forming a narrowing (55R) of said first corrugation, and wherein the step of removing the inerting device (200) comprises tilting the inflatable balloon (220) between the edge (68) and the narrowing (55R) after deflating the inflatable balloon (220).

5. A manufacturing method according to any one of claims 1 to 4, wherein the second metal sheet (44) has a welt (67) along said edge (68) of the second metal sheet (44).

6. A manufacturing method according to any one of claims 1 to 5, wherein the step of performing a continuous weld between the second metal sheet (44) and the first metal sheet (44) along the overlap zone (ZR) is performed by an automatic welding machine, the automatic welding machine moving parallel to said edges (68) of the first metal sheet (44) and the second metal sheet (44).

7. A manufacturing method according to any one of claims 1 to 6, wherein the support surface is an internal surface of a thermally insulating barrier.

8. A manufacturing method according to any one of claims 1 to 7, wherein the sealing membrane is a primary sealing membrane (15), the thermally insulating barrier is a primary thermally insulating barrier (14), and wherein the tank wall further comprises a secondary sealing membrane (13) and a secondary thermally insulating barrier (12), the secondary thermally insulating barrier resting against a load-bearing wall, the secondary sealing membrane (13) resting against the secondary thermally insulating barrier (12), and the primary thermally insulating barrier (14) resting against the secondary sealing membrane (13), wherein the primary thermally insulating barrier (14) comprises rows of load-bearing elements (30), each of the load-bearing elements being fixed to an external plate and an internal plate (42),the external trays being fixed to the secondary thermally insulating barrier (12) and pressing the secondary sealing membrane (13) against the secondary thermally insulating barrier (12), the internal trays (42) forming said support surface, and in which to arrange the first metal sheet (44) and the second metal sheet (44) on the support surface comprises welding the first metal sheet (44) and the second metal sheet (44) to said internal trays (42).

9. A manufacturing method according to claim 8, wherein placing the inerting device (200, 300) on the support surface comprises making route the gas supply line (290, 390) in gaps provided between the internal plates (42).

Images