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 (144) and a second metal sheet (44) are arranged, the second metal sheet (44) overlapping the first metal sheet (144) in an overlap zone (ZR). The first metal sheet (144) has a thickening piece (90) located at least in a portion of the overlap zone (ZR) to thicken the first metal sheet (144) at least at junctions (156a) between a corrugated portion (185a) of the first metal sheet (144) and two flat portions (186) of the first metal sheet (144). A continuous weld is made between the second metal sheet (44) and the first metal sheet (144) along the overlap zone (ZR), the continuous weld passing through the thickening piece (90). Figure for the abridged version: Fig. 5

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 tank wall sealing membrane for a sealed and thermally insulating liquefied gas storage tank, the manufacturing process comprising the following steps: - placing a first metal sheet and a second metal sheet on a flat support surface, the first metal sheet and the second metal sheet each comprising 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 overlapping 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 overlapping 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, and the first metal sheet carrying an extra thickness piece located at the right of at least part of the overlap area to thicken the first metal sheet at least at junctions between the corrugated portion of the first metal sheet and the two flat portions of the first metal sheet; - to perform a continuous weld between the second metal sheet and the first metal sheet along the overlap area, the continuous weld passing over the piece of extra thickness.

[0012] According to one embodiment, the invention also provides a sealed and thermally insulated tank for storing a liquefied gas, the tank comprising a tank wall having a flat support surface and a sealing membrane, in which the sealing membrane comprises a first metal sheet and a second metal sheet disposed on the 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 from 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 area defined between an edge of the first metal sheet and an edge of the 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 overlaps 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 overlap the two flat portions of the first metal sheet in the overlap zone, the The first metal sheet is located between the second metal sheet and the support surface in the overlap area. the first metal sheet bearing an additional thickness piece located at the right of at least part of the overlap area to thicken the first metal sheet at least at the junctions between the corrugated portion of the first metal sheet and the two flat portions of the first metal sheet, in which the sealing membrane has a continuous weld between the second metal sheet and the first metal sheet along the overlap area, the continuous weld passing over the piece of excess thickness.

[0013] The presence of the extra piece tends to prevent excessive melting of the metal alloy of the first metal sheet and hot oxidation of the metal alloy of the first metal sheet, and therefore tends to prevent the weld between the second metal sheet and the first metal sheet from exhibiting high residual porosity after the recrystallization of the metal alloy. Thus, thanks to the extra piece, the sealing membrane exhibits improved mechanical strength and less degradation of the vacuum sealing of a thermally insulating barrier under the sealing membrane.

[0014] Furthermore, since the extra thickness piece tends to isolate the metal alloy of the first metal sheet from the atmosphere, it is not necessary to carry out the continuous weld under an inert atmosphere on the reverse side.

[0015] According to embodiments, such a manufacturing process or such a tank may include one or more of the following characteristics.

[0016] Various geometries are conceivable for the extra thickness part.

[0017] According to one embodiment, the thicker piece extends continuously across the width of the corrugated portion of the first metal sheet, from one of the two flat portions of the first metal sheet to the other of the two flat portions of the first metal sheet.

[0018] According to one embodiment, the thickened part has a constant thickness. In this way, the thickened part can be manufactured at low cost, for example by stamping.

[0019] According to one embodiment, the thicker piece is thicker at the junctions between the corrugated portion and the two flat portions of the first metal sheet than at a part of the top of said corrugated portion.

[0020] Indeed, the risk of excessive melting of the metal alloy of the first metal sheet tends to be greater at the said junctions than at the top part; it is therefore preferable that the extra thickness piece be thicker at the junctions.

[0021] According to one embodiment, the thickened piece is attached to the two flat portions of the first metal sheet.

[0022] According to one embodiment, the thickening piece, the first metal sheet, and the second metal sheet are made of the same metal alloy. According to another embodiment, the thickening piece may be made of a different metal alloy than the metal alloy of the first and second metal sheets, in particular a less expensive metal alloy, since the thickening piece contributes little to the mechanical strength of the sealing membrane.

[0023] According to one embodiment, the second metal sheet has a welt along said edge of the second metal sheet.

[0024] 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.

[0025] According to one embodiment, the step of carrying out the continuous weld between the second metal sheet and the first metal sheet along the overlap area is not carried out under an inert atmosphere on the reverse side.

[0026] Indeed, an inert atmosphere on the reverse side is not necessary since the extra thickness piece tends to isolate the weld between the second metal sheet and the first metal sheet from the atmosphere present on the reverse side of the sealing membrane.

[0027] According to one embodiment, arranging the first metal sheet and the second metal sheet on the support surface includes positioning the first metal sheet by inserting the piece of extra thickness into a recess in the support surface.

[0028] According to one embodiment, the support surface is an internal surface of a thermally insulating barrier.

[0029] According to one embodiment, the sealing membrane is a primary sealing membrane, the thermally insulating barrier is a primary thermally insulating barrier, and 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 thermally insulating barrier, and the primary thermally insulating barrier resting against the secondary sealing membrane.

[0030] 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 an internal plate, the external plates being fixed to the thermal barrier. unically secondary insulating and pressing the secondary sealing membrane against the secondary thermally insulating barrier, the internal trays forming said support surface, and arranging the first metal sheet and the second metal sheet on the support surface includes welding the first metal sheet and the second metal sheet to said internal trays.

[0031] 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.

[0032] 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.

[0033] Since the second metal sheet is welded to the first metal sheet along the overlap area and the extra piece is supported by the first metal sheet, the extra piece remains permanently in the sealing membrane.

[0034] In one embodiment, the liquefied gas is liquid hydrogen.

[0035] 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.

[0036] 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.

[0037] 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 a floating or land-based storage facility.

[0038] 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.

[0039] 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 ca isolated connections from or to a floating or land-based storage facility to or from the ship's tank. Brief description of the figures

[0040] 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.

[0041] [Fig-1] [Fig. 1] is a partial perspective view of a tank wall of a tank Waterproof and thermally insulating.

[0042] [Fig.2] Fig.2 is a partial perspective view of a corrugated metal sheet carrying pieces of extra thickness.

[0043] [Fig. 3] [Fig. 3] is a side view, along arrow A in [Fig. 2], of a portion of the undulation of the corrugated metal sheet of [Fig.2].

[0044] [Fig.4] Fig.4 is a partial perspective view, showing the arrangement of corrugated metal sheets on the primary thermally insulating barrier of the tank wall of [Fig.l].

[0045] [Fig. 5] Fig. 5 is a perspective and partial sectional view of detail V of the [Fig.4],

[0046] [Fig.6] Fig.6 is a schematic cross-sectional view along a plane included in the overlap area visible on [Fig.5].

[0047] [Fig.7] [Fig.7] is a schematic cutaway representation of a ship's tank and a loading / unloading terminal for this tank. Description of the implementation methods

[0048] 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.

[0049] Figure 1 shows a partial perspective view of a tank wall 11 of a sealed, thermally insulated storage tank for a liquefied gas. The wall 11 shown is constructed according to the teachings of document WO 2023 / 198637 AL.

[0050] As described in document WO 2023 / 198637 AL, 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.

[0051] 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.

[0052] 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, which helps to reduce its thermal contraction.

[0053] 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.

[0054] 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.

[0055] 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 of the The series 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 an inner portion of the insulating polymer foam layer 17. Advantageously, the grooves 22 have a shape complementary to the corrugations of the secondary sealing membrane 13.

[0056] Furthermore, the insulating panels 16 have relaxation slots 27 which allow their stiffness to be reduced so that the secondary thermally insulating barrier 12 deforms as homogeneously as possible. This makes it possible to obtain the most uniform deformations possible of the corrugations of the secondary sealing membrane 13. Advantageously, the insulating panels 16 have relaxation slots 27 at least opposite each of the corrugations of 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 A1.

[0057] 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, consequently, resist the forces 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.

[0058] Further details on the load-bearing elements 30 can be found in document WO 2023 / 198637 AL. In particular, as described in this 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]).

[0059] 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 expansion is typically between 1.2 x 10⁶ and 2 x 10⁶ K⁻¹, or of a high-manganese iron alloy whose coefficient of expansion is typically around 7 x 10⁶ K⁻¹. Alternatively, the corrugated metal sheets 44 can also be made of stainless steel or aluminum.

[0060] The corrugated metal sheets 44 are welded with overlaps along their edges to ensure the watertightness of the primary sealing membrane 15. The primary sealing membrane 15 has corrugations 45. More specifically, it It comprises a first series of undulations 45a extending parallel to a first direction and a second series of undulations 45b extending parallel to a second direction. The directions of the series of undulations 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 project towards the interior of the tank, that is, in the opposite direction to the supporting structure 1. Each corrugated metal sheet 44 has, between the corrugations 45, a plurality of flat areas 46. The corrugations 45b are here less tall than the corrugations 45a. In another embodiment, the corrugations 45a and 45b could have the same height.

[0061] The pitch of the corrugations in the secondary sealing membrane 13 is equal to the pitch of the corrugations 45 in the primary sealing membrane 15 or to an integer multiple thereof. In addition, each of the corrugations of the secondary sealing membrane 13 is arranged opposite, along the thickness direction of the wall 11, a corrugation 45 of the primary sealing membrane 15.Thus, each flat area 46 of the primary waterproofing membrane 15 is located opposite, according to the thickness direction of the wall 11, a flat area of ​​the secondary waterproofing membrane 13. Therefore, the axis of each load-bearing element 30 passes through both the center of a flat area 46 of the primary waterproofing membrane 15 and the center of a flat area of ​​the secondary waterproofing membrane 13.

[0062] 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.

[0063] Further details on the primary thermally insulating barrier 14 can be found in document WO 2023 / 198637 AL. 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 has the particularity of being stored at approximately -253°C at atmospheric pressure. When the tank is filled with liquid hydrogen at -253°C at atmospheric pressure... Being spherical, the primary waterproofing membrane 15 is subjected to very high thermal stresses. It is therefore important to ensure the mechanical strength of the primary waterproofing membrane 15.

[0064] 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.

[0065] 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 greater the surface irregularity, which can lead to crack initiation. This is detrimental to the mechanical strength of the primary sealing membrane 15 and degrades the performance of the vacuuming of the primary thermally insulating barrier 14. Residual porosity primarily increases the specific surface area of ​​the metal surfaces, thereby increasing the theoretical degassing rate calculated from an underestimated nominal surface area. The performance of the vacuuming process can also be degraded by the creation of nearly enclosed spaces, which trap 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 due to the welding operation in the welds between corrugated metal sheets 44.

[0066] Embodiments of a manufacturing process for the primary sealing membrane 15 which tend to limit this residual porosity. This manufacturing process uses a corrugated metal sheet 144 (hereinafter "the sheet 144"), which is identical to the corrugated metal sheets 44 (hereinafter "the sheets 44") except that it carries pieces of extra thickness 90 represented in figures 2 to 6. Thus, the following description of sheet 144 is also applicable to sheets 44, the elements of sheet 144 which are identical to the elements of sheets 44 bearing the same reference signs increased by 100.

[0067] In [Fig.2], where the sheet 144 has been partially represented in perspective, it can be seen that the sheet 144 has flat portions 186 intended to rest on the internal plates 42 and corrugated portions 185a, 185b projecting from the flat portions 186. Each corrugated portion 185a, 185b is formed between two flat portions 186. The corrugated portions 185a, 185b are intended to constitute respectively a part of a corrugation 45a, 45b (see [Fig.1]) of the primary sealing membrane 15. For this purpose, the corrugated portions 185b have a smaller height here than the corrugated portions 185a. In another embodiment, the undulation portions 185a and 185b could have the same height.

[0068] Reference symbols 156a each designate a junction between a planar portion 186 and a corrugated portion 185a. Reference symbols 156b each designate a junction between a planar portion 186 and a corrugated portion 185b. Nodes 155 are formed at the intersections between the corrugated portions 185a and 185b. The nodes 155 have been omitted from Figures 1 and 4 to avoid cluttering the drawing.

[0069] The sheet 144 has a generally rectangular outer contour delimited by four straight edges 168 orthogonal to each other. Three of the four edges 168 are visible in [Fig. 2]. As shown, the corrugated portions 185a, 185b extend to the edges 168.

[0070] The sheet 144 carries a thickening piece 90 for each corrugation portion 185a. As shown in [Fig. 2], one edge of the thickening pieces 90 is preferably aligned with the edge 168 to which the corrugation portions 185a extend, or is spaced less than 5 mm from the edge 168. In the figures, the thickening piece 90 is shown as a monolithic piece. However, other embodiments are possible, for example, with a thickening piece comprising several parts, such as two small plates of varying thickness. According to a non-limiting example, the thickening piece 90 comprises a first small piece 2 mm thick at the toe of the corrugation and a second small piece 1.5 mm thick at the crest of the corrugation.

[0071] Fig. 3 is a side view, along arrow A in Fig. 2, of one of the corrugated portions 185a. As can be seen more clearly in Fig. 3, the thickening pieces 90 are positioned to thicken the sheet 144 at the corrugated portions 185a, the junctions 156a, and part of the flat portions 186 in the vicinity of the junctions 156a.

[0072] Still referring to [Fig.2], sheet metal 144 is silk-coated (or joggled; in English: "joggling") along at least one other edge 168, so that the sheet 144 has a joggling 167 along said edge 168. Preferably, as best seen in [Fig. 4], the sheet or each sheet 144 is joggling along two perpendicular edges 168, which correspond respectively to joggling 167 and joggling 67. (Joggling 67 is shown here on another rectangular sheet 44.) Preferably, pieces of extra thickness are placed in the corrugations near one or more edges 168 of the sheet 144 that lack joggling, for example along the two edges 168 that lack joggling 167 and 67.

[0073] In a first step of the manufacturing process, sheet metal 144 and sheet metal 44 are arranged. This first step is illustrated by [Fig. 4] and by [Fig. 5], which is a perspective and partial sectional view of detail V of [Fig. 4]. In [Fig. 5], the internal trays 42 have been omitted, and only sheet metal 144 and sheet metal 44 are shown in order to avoid cluttering the drawing.

[0074] As shown in [Fig.4], recesses 429 are provided on the internal plates 42 to receive the thicker pieces 90. It can also be seen in [Fig.4] that the internal plates 42 have through holes 423. These through holes 423 are intended to receive rivets distributed around the axis of the carrier element 30 to fix the carrier element 30 to the internal plates 42 as described in document WO 2023 / 198637 A1.

[0075] The sheet metal 144 is positioned by inserting the thicker pieces 90 into the recesses 429.

[0076] With the sheet 144 thus positioned, a sheet 44 is positioned whose edge 67 overlaps the sheet 144 in an overlap zone ZR. With reference to [Fig. 5], the overlap zone ZR is defined between an edge 168 of the sheet 144 and an edge 68 of the sheet 44 that is parallel to the edge 168. The dashed lines on [Fig. 5] indicate the position of the overlap zone ZR. As shown on [Fig. 5], the corrugation portion 185a of the sheet 144 and the corrugation portion 85a of the sheet 44 are aligned; one end of the corrugation portion 85a overlaps the end of the corrugation portion 185a in the overlap zone ZR; and the flat portions 86 on either side of the undulating portion 85a cover the flat portions 186 on either side of the undulating portion 185a in the overlap zone ZR. Only one of the flat portions 86 is visible on the [Fig.[5], sheet metal 44 having been cut along the corrugation portion 85a in order to show the thickening piece 90. The thickening piece 90 is located at the right of at least part of the overlap zone ZR.

[0077] It will be understood that when the sheet metal 44 and the sheet metal 144 are positioned in this way, their flat portions 86, 186 rest on internal plates 42 (see [Fig. 4]). These internal plates 42 form a support surface for the sheet metal 44 and the sheet metal 144, and by This provides a support surface for the primary sealing membrane 15. Before proceeding to the second step, the sheets 44 and 144 are anchored by welding along their edges 68, 168, to the internal plates 42 as mentioned above. For example, sheet 144 is welded to the internal plates 42 before positioning sheet 44 to overlap sheet 144 in the overlap zone ZR.

[0078] In a second step of the manufacturing process, a continuous weld is made between sheet 44 and sheet 144 along the overlap zone ZR, the continuous weld passing over the excess piece 90. This second step is illustrated in [Fig. 6]. The continuous weld is made 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 168, 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 second step, sheet 44 is therefore overlap-welded to sheet 144 along the overlap zone ZR.

[0079] 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.

[0080] It should be noted that since the sheet 44 is welded with an overlap to the sheet 144 along the overlap zone ZR and the thickening piece 90 is supported by the sheet 144, the thickening piece 90 remains permanently in the primary sealing membrane 15 at the end of the manufacturing process.

[0081] Although not shown in [Fig. 4], 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.

[0082] Furthermore, it should be noted that, alternatively or in addition to the corrugation sections 185a, the sheet 144 can carry reinforcement pieces similar to the reinforcement pieces 90 at the corrugation sections 185b. The lap weld of the sheet 44 to the sheet 144 at such reinforcement pieces is identical to that described previously. In other words, the sheet 144 can carry a reinforcement piece in the large corrugations and / or in the small corrugations.

[0083] Figure 6 is a schematic view of sheet metal 44 and sheet metal 144 shown in Figure 5, in cross-section along a plane included in the overlap zone ZR and parallel to the direction of travel W. It is specified that the sheets 44, 144 and the part on thickness 90 are schematically represented by lines to facilitate the explanation that will follow.

[0084] Figure 6 shows three successive positions of a welding torch 900 during the second stage of the manufacturing process, represented by dashed lines. As shown in Figure 6, the welding torch 900 can be mounted for rotation to follow the outer contour of the corrugated portions 85a and 185a. The welding torch 900 can be mounted on an automatic welding machine as mentioned above. Due to the presence of the reinforcement piece 90, the sheet metal 144 exhibits increased thermal inertia at the corrugated portion 185a, the joints 156a, and a portion of the flat sections 186 near the joints 156a. Furthermore, the reinforcement piece 90 tends to insulate the weld between the sheet metal 44 and the sheet metal 144 from the atmosphere.The presence of the 90 reinforcement piece helps prevent excessive melting of the metal alloy of the sheet 144 and hot oxidation of the metal alloy of the sheet 144, and therefore helps prevent the weld between the sheet 44 and the sheet 144 from exhibiting high residual porosity after the recrystallization of the metal alloy. Thus, thanks to the 90 reinforcement piece, the primary sealing membrane 15 has improved mechanical strength and less degradation of the vacuum sealing of the primary thermally insulating barrier 14. Furthermore, since the 90 reinforcement piece isolates the metal alloy of the sheet 144 from the atmosphere, it is not necessary to perform the continuous weld under an inert atmosphere on the reverse side.

[0085] According to one variant, the thickening piece 90 is made of the same metal alloy as the sheets 44, 144. According to another variant, the thickening piece 90 can be made of a different metal alloy than the metal alloy of the sheets 44, 144, in particular of a less expensive and metallurgically compatible metal alloy (i.e. that this alloy must be able to be welded without difficulty and without generating galvanic corrosion), because the thickening piece 90 contributes little to the mechanical strength of the primary sealing membrane 15.

[0086] In the embodiment shown in Figures 2 to 6, the thickened piece 90 extends continuously across the width of the corrugated portion 185a between the two flat portions 186 on either side of the corrugated portion 185a, and has a constant thickness. In this way, the thickened piece 90 can be manufactured at low cost, for example by deep drawing.

[0087] Alternatively, the 90 mm thicker piece can have different geometries.

[0088] In particular, according to one variant, the thicker piece 90 is thicker at the junctions 156a than at the crest portion 185at (see [Fig. 3]) of the corrugated section 185a. Indeed, due to the rotation of the welding torch 900 to follow the outer contour of the corrugated sections 85a, 185a, the risk of melting Excessive metal alloy of sheet 144 tends to be greater at the junctions 156a than at the top part 185at; it is therefore preferable that the piece of extra thickness 90 be thicker at the junctions 156a, in order to provide even greater thermal inertia at the junctions 156a.

[0089] For this reason, it is also conceivable that, according to another variant, the thickening pieces 90 are positioned to thicken the sheet 144 only at the junctions 156a. In other words, according to this variant, the sheet 144 has a thickening piece 90 at each junction 156a, these thickening pieces 90 not extending across the width of the corrugation portion 185a to the other junction 156a corresponding to this corrugation portion.

[0090] In the variants described above, the reinforcement pieces 90 are preferably attached to the sheet 144 to facilitate the manufacturing of the sheet 144. For example, the reinforcement pieces 90 are attached to the sheet 144 by tack welding. Even more preferably, the reinforcement pieces 90 are tack welded to both the flat portions 186 of the sheet 144 and the corrugated portions 185a and / or 185b. This ensures that the reinforcement pieces 90 are sufficiently attached to remain in place during the handling of the sheets.

[0091] The manufacturing process has been described in the context of a sealed and thermally insulated tank for storing liquefied hydrogen. Alternatively, the sealed and thermally insulated tank can be used to store other liquefied gases, in particular liquefied natural gas (LNG), liquefied petroleum gas (LPG), ethane, or ammonia.

[0092] The manufacturing process has been described in the context of a tank wall produced according to the teachings of document WO 2023 / 198637 AL. However, the manufacturing process is 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, 144 are anchored by their edges to the anchor plates and not to the internal plates 42 described above.

[0093] With reference to [Fig. 7], a cutaway view of a vessel 70 shows a watertight and thermally insulating tank 71 of generally prismatic shape mounted in the double hull 72 of the ship. 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 ship, 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.

[0094] 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.

[0095] Figure 7 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 the dimensions of hydrogenerators. An unshown connecting pipeline extends inside tower 78. The loading and unloading station 75 allows the loading and unloading of the hydrogenerator 70 from or to the onshore facility 77. This facility 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 installation 77 over a long distance, for example 5 km, which allows the hydrogenerator vessel 70 to be kept a long distance from the coast during loading and unloading operations.

[0096] 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 pressure rise in the internal space of the tank under the effect of the evaporation of the liquefied gas stored in the tank.

[0097] 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.

[0098] The use of the verb "to include", "to understand" or "to include" and its conjugated forms does not exclude the presence of other elements or other steps than those stated in a claim.

[0099] In the claims, any reference sign in parentheses shall not be interpreted as a limitation of the claim.

Claims

Demands

1. A manufacturing process for producing a tank wall sealing membrane for a sealed and thermally insulating liquefied gas storage tank, the manufacturing process comprising the following steps: - to arrange a first metal sheet (144) and a second metal sheet (44) on a flat support surface, the first metal sheet (144) and the second metal sheet (44) each having two flat portions (186, 86) resting on the flat support surface and a corrugated portion (185a, 85a) formed between the two flat portions (186, 86), the corrugated portion (185a, 85a) being projecting from the two flat portions (186, 86), the corrugated portion (185a) of the first metal sheet (144) and the corrugated portion (85a) of the second metal sheet (44) being aligned, the second metal sheet (44) covering the first metal sheet (144) in an overlap zone (ZR) defined between an edge (168) of the first metal sheet (144) and an edge (68) of the second metal sheet (44) parallel to the edge (168) of the first metal sheet (144), the corrugated portion (185a) of the first metal sheet (144) extending to said edge (168) of the first metal sheet (144) and the corrugated portion (85a) of the second metal sheet (44) extending to said edge (68) of the second metal sheet (44), one end of the corrugated portion (85a) of the second metal sheet (44) overlapping one end of the corrugated portion (185a) of the first metal sheet (144) in the overlap zone (ZR) and the two flat portions (86) of the second metal sheet (44) overlapping the two flat portions (186) of the first metal sheet (144) in the overlap zone (ZR), the first metal sheet (144) being located between the second metal sheet (44) and the support surface in the overlap zone (ZR), and the first metal sheet (144) carrying an additional thickness piece (90) located at the right of at least part of the overlap zone (ZR) to thicken the first metal sheet (144) at least at junctions (156a) between the corrugated portion (185a) of the first metal sheet (144) and the two flat portions (186) of the first metal sheet metal (144); - to carry out a continuous weld between the second metal sheet (44) and the first metal sheet (144) along the overlap zone (ZR), the continuous weld passing over the piece of excess thickness (90).

2. A manufacturing method according to claim 1, wherein the piece of extra thickness (90) extends continuously in a width of the corrugated portion (185a) of the first metal sheet (144), from one of the two flat portions (186) of the first metal sheet (144) to the other of the two flat portions (186) of the first metal sheet (144).

3. A manufacturing method according to claim 2, wherein the extra thickness piece (90) is thicker at said junctions (156a) between the corrugated portion (185a) and the two flat portions (186) of the first metal sheet (144) than at a top portion (185at) of said corrugated portion (185a).

4. A manufacturing method according to any one of claims 1 to 3, wherein the extra thickness piece (90) is attached to the two flat portions (186) of the first metal sheet (144).

5. A manufacturing method according to any one of claims 1 to 4, wherein the extra thickness piece (90), the first metal sheet (144) and the second metal sheet (44) are made of the same metal alloy.

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

7. A manufacturing method according to any one of claims 1 to 6, wherein the step of performing a continuous weld between the second metal sheet (44) and the first metal sheet (144) along the overlap zone (ZR) is performed by an automatic welding machine, the automatic welding machine moving parallel to said edges (168, 68) of the first metal sheet (144) and the second metal sheet (44).

8. A method of manufacturing any one of claims 1 to 7, wherein arranging the first metal sheet (144) and the second metal sheet (44) on the support surface comprises positioning the first metal sheet (144) by inserting the piece of extra thickness (90) into a recess (429) that has the support surface.

9. A manufacturing method according to any one of claims 1 to 8, wherein the support surface is an internal surface of a thermally insulating barrier.

10. A manufacturing method according to claim 9, 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 (11) further comprises a secondary sealing membrane (13) and a secondary thermally insulating barrier (12), the secondary thermally insulating barrier (12) 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 (144) and the second metal sheet (44) on the support surface includes welding the first metal sheet (144) and the second metal sheet (44) to said internal trays (42).

11. A sealed and thermally insulating tank for storing a liquefied gas, the tank comprising a tank wall having a flat support surface and a sealing membrane, wherein the sealing membrane comprises a first metal sheet (144) and a second metal sheet (44) disposed on the flat support surface, the first metal sheet (144) and the second metal sheet (44) each having two flat portions (186, 86) resting on the flat support surface and a corrugated portion (185a, 85a) formed between the two flat portions (186, 86), the corrugated portion (185a, 85a) projecting from the two flat portions (186, 86), the corrugated portion (185a) of the first metal sheet (144) and the corrugated portion (85a) of the second metal sheet (44) being aligned, the second metal sheet (44) covering the first metal sheet (144) in an overlap zone (ZR) defined between an edge (168) of the first metal sheet (144) and an edge (68) of the second metal sheet (44) parallel to the edge (168) of the first metal sheet (144), the corrugated portion (185a) of the first metal sheet (144) extending to said edge (168) of the first metal sheet (144) and the corrugated portion (85a) of the second metal sheet (44) extending to said edge (68) of the second metal sheet (44), one end of the corrugated portion (85a) of the second metal sheet (44) overlapping one end of the corrugated portion (185a) of the first metal sheet (144) in the overlap zone (ZR) and the two flat portions (86) of the second metal sheet (44) overlapping the two flat portions (186) of the first metal sheet (144) in the overlap zone (ZR),the first metal sheet (144) being located between the second metal sheet (44) and the support surface in the overlap zone (ZR), the first metal sheet (144) having a thickening piece (90) located at least in a portion of the overlap zone (ZR) to thicken the first metal sheet (144) at least at junctions (156a) between the corrugated portion (185a) of the first metal sheet (144) and the two flat portions (186) of the first metal sheet (144), wherein the sealing membrane has a continuous weld between the second metal sheet (44) and the first metal sheet (144) along the overlap zone (ZR), the continuous weld passing through the thickening piece (90).

12. Vessel (70) for the transport of a liquefied gas, the vessel comprising a double hull (72) and a tank (71) according to claim 11 disposed in the double hull.

13. Transfer system for a liquefied gas, the system comprising a vessel (70) according to claim 12, insulated pipelines (73, 79, 76, 81) arranged to connect the tank (71) installed in the hull of the vessel to a floating or land-based storage facility (77) and a pump to drive a flow of liquefied gas through the insulated pipelines from or to the floating or land-based storage facility to or from the vessel's tank.

14. A method for loading or unloading a ship (70) according to claim 12, wherein a liquefied gas is conveyed through insulated pipelines (73, 79, 76, 81) from or to a floating or land-based storage facility (77) to or from the vessel's tank (71) (70).

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