Manufacturing method for producing a sealing membrane for a sealed and thermally insulating tank for storing liquefied gas

Abstract

The invention relates to a manufacturing method for producing a sealing membrane for a sealed and thermally insulating tank for storing liquefied gas, the method comprising: a step of positioning a first metal sheet (144) and a second metal sheet (44), wherein the second metal sheet (44) covers the first metal sheet (144) in a region of overlap (ZR). The first metal sheet (144) carries an extra-thick part (90) located in line with at least part of the region of overlap (ZR), in order 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). The method also comprises a step of forming a continuous weld between the second metal sheet (44) and the first metal sheet (144) along the region of overlap (ZR), wherein the continuous weld runs directly over the extra-thick part (90).

Description

Manufacturing method for manufacturing a sealing membrane for a sealed and thermally insulating tank for storing liquefied gas

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

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

[0003] Document WO 2023 / 198637 A1 discloses a tank in which the walls have a multi-layer structure, i.e. successively have, in the direction of thickness of the wall, from the outside to the inside, a secondary thermally insulating barrier retained on the supporting 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 attached to an outer tray and an inner tray, the outer trays being attached to the secondary thermally insulating barrier and pressing the secondary waterproofing membrane against the secondary thermally insulating barrier, the inner trays forming a support surface for the primary waterproofing membrane.

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

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

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

[0008] On the other hand, to give the primary thermally insulating barrier the required thermally insulating properties, the primary thermally insulating barrier has a gas 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 waterproofing membrane and the impact of the primary waterproofing membrane on the vacuumization of the primary thermally insulating barrier, there is the presence of residual porosity in the welds between the corrugated metal sheets of the primary waterproofing membrane. If the welding operation causes excessive melting of the metal alloy of the corrugated metal sheets, the welds between the corrugated metal sheets may have high residual porosity. This risk is greater when the welding operation is not carried out under an inert atmosphere, because then the metal alloy is likely to undergo 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 they present a surface irregularity likely to generate crack initiations which are detrimental to the mechanical strength of the primary waterproofing membrane, and the more they are likely to degrade the vacuum performance of the primary thermally insulating barrier.

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

[0011] According to one embodiment, the invention provides a manufacturing method for manufacturing a sealing membrane for a tank wall for a sealed and thermally insulating tank for storing a liquefied gas, the manufacturing method comprising the following steps: - arranging 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 corrugation portion formed between the two flat portions, the corrugation portion projecting relative to the two flat portions, the corrugation portion of the first metal sheet and the corrugation portion of the second metal sheet being aligned,the second metal sheet covering the first metal sheet in an overlapping 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 corrugation portion of the first metal sheet extending to said edge of the first metal sheet and the corrugation portion of the second metal sheet extending to said edge of the second metal sheet, one end of the corrugation portion of the second metal sheet covering one end of the corrugation portion of the first metal sheet in the overlapping area and the two flat portions of the second metal sheet covering the two flat portions of the first metal sheet in the overlapping area, the first metal sheet being located between the second metal sheet and the support surface in the overlapping area,andthe first metal sheet carrying an excess thickness piece located in line with at least part of the overlap zone 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;- making a continuous weld between the second metal sheet and the first metal sheet along the overlap zone, the continuous weld passing in line with the excess thickness piece.,

[0012] According to one embodiment, the invention also provides 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 and a second metal sheet arranged on the 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 corrugation portion formed between the two flat portions, the corrugation portion projecting relative to the two flat portions, the corrugation portion of the first metal sheet and the corrugation portion of the second metal sheet being aligned,the second metal sheet covering the first metal sheet in an overlapping 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 corrugation portion of the first metal sheet extending to said edge of the first metal sheet and the corrugation portion of the second metal sheet extending to said edge of the second metal sheet, one end of the corrugation portion of the second metal sheet covering one end of the corrugation portion of the first metal sheet in the overlapping area and the two flat portions of the second metal sheet covering the two flat portions of the first metal sheet in the overlapping area, the first metal sheet being located between the second metal sheet and the support surface in the overlapping area,the first metal sheet carrying an excess thickness piece located in line with at least part of the overlap zone 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, in which the sealing membrane comprises a continuous weld between the second metal sheet and the first metal sheet along the overlap zone, the continuous weld passing in line with the excess thickness piece.,

[0013] The presence of the extra thickness part 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 having high residual porosity after recrystallization of the metal alloy. Thus, thanks to the extra thickness part, the sealing membrane has improved mechanical strength and less degrades the vacuuming of a thermally insulating barrier under the sealing membrane.

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

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

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

[0017] According to one embodiment, the excess thickness piece extends continuously in a width of the corrugation 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 excess thickness part has a constant thickness. In this way, the excess thickness part can be manufactured at low cost, for example by stamping.

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

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

[0021] According to one embodiment, the excess thickness part is attached to the two flat portions of the first metal sheet.

[0022] According to one embodiment, the excess thickness part, the first metal sheet and the second metal sheet are made of the same metal alloy. According to another embodiment, the excess thickness part may be made of a metal alloy different from the metal alloy of the first metal sheet and the second metal sheet, in particular of a less expensive metal alloy, because the excess thickness part contributes little to the mechanical strength of the waterproofing membrane.

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

[0024] According to one embodiment, the step of performing a continuous weld between the second metal sheet and the first metal sheet along the overlap area is performed 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 welding between the second metal sheet and the first metal sheet along the overlap zone is not carried out under an inert atmosphere on the reverse side.

[0026] In fact, an inert atmosphere on the reverse side is not necessary since the excess thickness part 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 waterproofing membrane.

[0027] According to one embodiment, arranging the first metal sheet and the second metal sheet on the support surface comprises positioning the first metal sheet by inserting the excess thickness piece into a recess that the support surface comprises.

[0028] According to one embodiment, the support surface is an inner 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 supporting elements, each of the supporting elements being fixed to an outer plate and to an inner plate, the outer plates being fixed to the secondary thermally insulating barrier and pressing the secondary sealing membrane against the secondary thermally insulating barrier, the inner 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 inner plates.

[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 comprising 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 method 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 excess thickness piece is carried by the first metal sheet, the excess thickness piece remains permanently in the waterproofing 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, coastal, or deep-water structure, including a liquid hydrogen transport vessel, i.e., a hydrogen carrier, 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 transporting a liquefied gas comprises a double hull and a aforementioned tank arranged 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 pipes arranged so as to connect the tank installed in the hull of the vessel to a floating or land-based storage installation.

[0038] According to one embodiment, the transfer system also comprises a pump for driving a flow of liquefied gas through the insulated pipelines from or to the floating or land-based storage facility to or from the vessel tank.

[0039] According to one embodiment, the invention also provides a method of loading or unloading such a vessel, in which a liquefied gas is conveyed through insulated pipes from or to a floating or land-based storage facility to or from the vessel's tank. Brief description of the figures

[0040] The invention will be better understood, and other objects, details, characteristics and advantages thereof will appear more clearly during the following description of several particular embodiments of the invention, given solely for illustrative and non-limiting purposes, with reference to the accompanying drawings.

[0041] This is a partial perspective view of a tank wall of a sealed and thermally insulating tank.

[0042] This is a partial perspective view of a corrugated metal sheet bearing extra thickness pieces.

[0043] This is a side view, according to arrow A on the, of a portion of corrugation of the corrugated metal sheet of the.

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

[0045] This is a perspective and partial sectional view of detail V of the.

[0046] This is a schematic sectional view according to a plan included in the overlap area visible on the.

[0047] This is a schematic cutaway representation of a ship's tank and a terminal for loading / unloading this tank.

[0048] By convention, the terms "external" and "internal" are used to define the relative position of one element to another, with reference to the inside and outside of the tank.

[0049] In the, a tank wall 11 of a sealed and thermally insulating tank for storing liquefied gas is partially shown in perspective. The wall 11 shown is produced according to the teaching of document WO 2023 / 198637 A1.

[0050] As described in WO 2023 / 198637 A1, the wall 11 is fixed against a load-bearing wall forming part of a load-bearing structure 1, for example polyhedral. The load-bearing structure 1 is, for example, formed by the double hull of a ship. The wall 11 has a multi-layer structure comprising, along the thickness direction of the wall 11, from the outside to the inside, 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 supporting structure 1. 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 18 and outer 19 plates are, for example, plywood plates glued to said layer of insulating polymer foam 17. According to a variant, the inner 18 and outer 19 plates are made from a polymer matrix reinforced by fibers, such as glass fibers. The insulating polymer foam may in particular be a polyurethane-based foam. The polymer foam is, advantageously, reinforced by fibers, such as glass fibers, contributing to reducing 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 18 and outer 19 plates are, for example, plywood plates glued to said layer of insulating polymer foam 17. According to one variant, the inner 18 and outer 19 plates are made from a polymer matrix reinforced by fibers, such as glass fibers. The insulating polymer foam may in particular be a polyurethane-based foam. The polymer foam is advantageously reinforced by fibers, such as glass fibers, helping to reduce its thermal contraction.

[0053] Advantageously, portions of mastic 20 are interposed between the external plate 19 of the insulating panels 16 and the supporting structure 1. The portions of mastic 20 thus contribute to compensating for the surface irregularities of the supporting structure 1. According to an advantageous alternative embodiment, the portions of mastic 20 adhere to the external plate 19 of the insulating panels 16 and to the supporting structure 1. The portions of mastic 20 thus participate in anchoring the insulating panels 16 on the supporting structure 1. In such an alternative embodiment, the secondary anchoring devices are optional.

[0054] The insulating panels 16 have substantially the shape of a rectangular parallelepiped and are juxtaposed in parallel rows and separated from each other by gaps 21 ensuring functional assembly clearance. The gaps 21 are filled with a heat-insulating filling, 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, as described in applications WO2019155157 or WO2021028624, for example.

[0055] In the embodiment shown, the internal face of the insulating panels 16 has two series of grooves 22 perpendicular to each other and intended to receive corrugations 24, projecting towards the outside of the tank, formed on the corrugated metal sheets 25 of the secondary waterproofing membrane 13. Each of the series of grooves 22 is parallel to two opposite sides of the insulating panels 16. In the embodiment shown, the grooves 22 pass entirely through the thickness of the internal plate 10 as well as an internal portion of the layer of insulating polymer foam 17. Advantageously, the grooves 22 have a shape complementary to those of the corrugations that the secondary waterproofing membrane 13 comprises.

[0056] Furthermore, the insulating panels 16 have relaxation slots 27 which make it possible to reduce their stiffness so that the secondary thermally insulating barrier 12 deforms in the most homogeneous manner possible. This makes it possible to obtain the most uniform deformations possible of the corrugations of the secondary waterproofing membrane 13. Advantageously, the insulating panels 16 have relaxation slots 27 at least opposite each of the corrugations of the secondary waterproofing membrane 13. More details on the thermally insulating barrier 12 and the secondary waterproofing 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 which extend in the thickness direction of the wall 11. The load-bearing elements 30 make it possible to support the primary sealing membrane 15 and, consequently, to take up the forces due to the 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 supporting elements 30 can be found in WO 2023 / 198637 A1. In particular, as described in this document, the supporting elements 30 are each attached 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 the but shown in the).

[0059] The primary waterproofing membrane 15 is obtained by assembling a plurality of corrugated metal sheets 44. The corrugated metal sheets 44 each have a substantially rectangular shape. The corrugated metal sheets 44 are, for example, made of Invar®: that is to say an alloy of iron and nickel whose coefficient of expansion is typically between 1.2.10 -6 and 2.10 -6 K -1 , or in an iron alloy with a high manganese content whose coefficient of expansion is typically of the order of 7.10 -6 K -1 Alternatively, the corrugated metal sheets 44 can also be made of stainless steel or aluminum.

[0060] The corrugated metal sheets 44 are overlap welded along their edges in order to ensure the sealing of the primary waterproofing membrane 15. The primary waterproofing membrane 15 comprises corrugations 45. More particularly, it comprises 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 supporting 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 inside of the tank, i.e. in the opposite direction to the supporting structure 1. Each corrugated metal sheet 44 comprises between the corrugations 45, a plurality of flat areas 46. The corrugations 45b here have a smaller height than the corrugations 45a.In another embodiment, the corrugations 45a and 45b could have the same height.

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

[0062] The corrugated metal sheets 44 of the primary waterproofing 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 transparent welds. According to an advantageous embodiment, the corrugated metal sheets 44 are welded to each of the internal plates 42 which support them. Such an embodiment is particularly advantageous in that it makes it possible to distribute the stresses even more uniformly between the corrugations 45 of the primary waterproofing membrane 15.

[0063] More 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 producing a sealed and thermally insulating tank for storing liquid hydrogen. Liquid hydrogen is a liquefied gas which 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, the primary sealing membrane 15 is subjected to very significant thermal stresses. It is therefore important to ensure the mechanical strength of the primary sealing membrane 15.

[0064] Furthermore, still as described in document WO 2023 / 198637 A1, in order to give the primary thermally insulating barrier 14 the required thermally insulating properties, the primary thermally insulating barrier 14 has a gas phase which is placed at an absolute pressure of less than 1 Pa, advantageously less than 10 -1 Pa, preferably less than 10 –2 Pa and for example of the order of 10 -3 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 is not degraded by the primary sealing membrane 15.

[0065] As mentioned above, the corrugated metal sheets 44 are lap welded along their edges to seal the primary waterproofing 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 have high residual porosity after recrystallization of the metal alloy. This risk is greater when the welding operation is not carried out under an inert atmosphere, because then the metal alloy is likely to undergo 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 they present a surface irregularity likely to generate crack initiations which are detrimental to the mechanical strength of the primary sealing membrane 15, and the more they are likely to degrade the vacuum performance of the primary thermally insulating barrier 14. The residual porosity will mainly increase the specific surface area of ​​the metal surfaces, thereby increasing the theoretical degassing rate calculated from an underestimated nominal surface area. The vacuum performance can also be degraded by the creation of almost closed spaces, seats of a volume of gas which will be all the more difficult to evacuate by pumping as the resistance to flow at the outlet of these spaces is great.Therefore, it is particularly desirable to limit residual porosity due to the welding operation in the welds between the corrugated metal sheets 44.

[0066] Embodiments of a method for manufacturing the primary waterproofing membrane 15 which tend to limit this residual porosity are described below. This manufacturing method 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 shown in FIGS. 2 to 6. Thus, the following description of the sheet 144 is also applicable to the sheets 44, the elements of the sheet 144 which are identical to the elements of the sheets 44 bearing the same reference signs increased by 100.

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

[0068] The reference signs 156a each designate a junction between a planar portion 186 and a corrugation portion 185a. The reference signs 156b each designate a junction between a planar portion 186 and a corrugation portion 185b. Nodes 155 are formed at the intersections between the corrugation portions 185a, 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 which is delimited by four straight edges 168 orthogonal to each other. Three of the four edges 168 are visible in the. As shown, the corrugation portions 185a, 185b extend to the edges 168.

[0070] The sheet 144 carries an excess thickness part 90 per corrugation portion 185a. As shown in the, an edge of the excess thickness parts 90 is preferably aligned with the edge 168 up to which the corrugation portions 185a extend or is spaced from the edge 168 by a distance of less than 5 mm. In the figures, the excess thickness part 90 is shown as a monolithic part. However, other implementations are possible, for example with an excess thickness part comprising several parts, for example two small thickness plates. According to a non-limiting example, the excess thickness part 90 comprises a first small part 2 mm thick at the base of the corrugation and a second small part 1.5 mm thick at the top of the corrugation.

[0071] This is a side view, along arrow A in the, of one of the corrugation portions 185a. As is better seen in the, the extra thickness pieces 90 are positioned to thicken the sheet 144 at the corrugation portions 185a, the junctions 156a, and a portion of the flat portions 186 in the vicinity of the junctions 156a.

[0072] Still with reference to the, the sheet 144 is joggled along at least one other of the edges 168, such that the sheet 144 has a joggling 167 along said edge 168. Preferably, as best seen in the, the or each sheet 144 is joggled along two perpendicular edges 168, which correspond respectively to the joggling 167 and to the joggling 67. (The joggling 67 is shown here on another rectangular sheet 44.) Preferably, pieces of excess thickness are placed in the corrugations near one or more edges 168 of the sheet 144 that are not joggled, for example along the two edges 168 that are not joggled by the jogglings 167 and 67.

[0073] In a first step of the manufacturing process, sheet 144 and sheet 44 are arranged. This first step is illustrated by and by, which is a perspective and partial sectional view of detail V of. In, the internal plates 42 have been omitted and only sheet 144 and sheet 44 are shown so as not to overload the drawing.

[0074] As shown in the, recesses 429 are provided on the internal plates 42 to receive the extra thickness parts 90. It can also be seen 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 144 is positioned by inserting the extra thickness pieces 90 into the recesses 429.

[0076] The sheet 144 having been thus positioned, a sheet 44 is positioned whose groove 67 covers the sheet 144 in an overlap zone ZR. With reference to 1a, the overlap zone ZR is defined between an edge 168 of the sheet 144 and an edge 68 of the sheet 44 which is parallel to the edge 168. The dotted lines on 1a indicate the position of the overlap zone ZR. As shown in 1a, 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 covers the end of the corrugation portion 185a in the overlap zone ZR; and the flat portions 86 on either side of the corrugation portion 85a overlap the flat portions 186 on either side of the corrugation portion 185a in the overlap zone ZR.Only one of the flat portions 86 is visible on the, the sheet 44 having been cut along the corrugation portion 85a in order to show the excess thickness part 90. The excess thickness part 90 is located at right angles to at least part of the overlap zone ZR.

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

[0078] In a second step of the manufacturing method, a continuous weld is made between the sheet 44 and the sheet 144 along the overlap zone ZR, the continuous weld passing in line with the excess thickness part 90. This second step is illustrated in the. The continuous weld is made according to known welding techniques by 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 the indicates the direction of advance of the automatic welding machine. The automatic welding machine can for example be constructed as described in document EP 0 611 217 A1. At the end of the second step, the sheet 44 is therefore overlap welded to the sheet 144 along the overlap zone ZR.

[0079] The above-described steps of the manufacturing process are repeated as necessary until the manufacturing of the primary waterproofing membrane 15 is completed.

[0080] It should be noted that since the sheet 44 is overlap welded to the sheet 144 along the overlap zone ZR and the excess thickness part 90 is carried by the sheet 144, the excess thickness part 90 remains permanently in the primary waterproofing membrane 15 at the end of the manufacturing process.

[0081] Although not shown in the, the invention also applies in the case where an internal plate 42 is connected to another internal plate 42 which is adjacent to it by a connection which has a degree of freedom in translation in a direction perpendicular to the direction of thickness of the wall and a degree of connection in the direction of thickness of the wall. This allows the internal plates on which the flat portions 186 of the waterproofing membrane are fixed to perform relative movements in the direction perpendicular to the direction of thickness of the wall.

[0082] Furthermore, it should be noted that, alternatively or additionally to the corrugation portions 185a, the sheet 144 may carry excess thickness pieces similar to the excess thickness pieces 90 at the corrugation portions 185b. The overlap welding of the sheet 44 to the sheet 144 at the level of such excess thickness pieces is identical to what was described previously. In other words, the sheet 144 may carry an excess thickness piece in the large corrugations and / or in the small corrugations.

[0083] This is a schematic view of the sheet 44 and the sheet 144 shown in the, in section along a plane included in the overlap zone ZR and parallel to the direction of advancement W. It is specified that the sheets 44, 144 and the excess thickness part 90 are shown diagrammatically by lines in order to facilitate the explanation which follows.

[0084] In the, three successive positions of a welding torch 900 during the second step of the manufacturing process are shown in dotted lines. As shown in the, the welding torch 900 can be mounted so as to be movable in rotation so as to follow the external contour of the corrugation portions 85a, 185a. The welding torch 900 can be mounted on an automatic welding machine as mentioned above. Due to the presence of the excess thickness piece 90, the sheet 144 has increased thermal inertia at the corrugation portion 185a, the junctions 156a, and a portion of the flat portions 186 in the vicinity of the junctions 156a. In addition, the excess thickness piece 90 tends to isolate the weld between the sheet 44 and the sheet 144 from the atmosphere.The presence of the excess thickness piece 90 tends to prevent excessive melting of the metal alloy of the sheet 144 and hot oxidation of the metal alloy of the sheet 144, and therefore tends to prevent the weld between the sheet 44 and the sheet 144 from having high residual porosity after recrystallization of the metal alloy. Thus, thanks to the excess thickness piece 90, the primary sealing membrane 15 has improved mechanical strength and degrades the vacuum of the primary thermally insulating barrier 14 less. Furthermore, since the excess thickness piece 90 tends to isolate the metal alloy of the sheet 144 from the atmosphere, it is not necessary to carry out the continuous weld under an inert atmosphere on the reverse side.

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

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

[0087] Alternatively, the extra thickness part 90 may have different geometries.

[0088] In particular, according to one variant, the excess thickness part 90 is thicker at the junctions 156a than at the top portion 185at (cf.) of the corrugation portion 185a. Indeed, due to the rotation of the welding torch 900 to follow the outer contour of the corrugation portions 85a, 185a, the risk of excessive melting of the metal alloy of the sheet 144 tends to be greater at the junctions 156a than at the top portion 185at; it is therefore preferable for the excess thickness part 90 to 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, pieces of extra thickness 90 are positioned to thicken the sheet 144 only at the junctions 156a. In other words, according to this variant, the sheet 144 carries a piece of extra thickness 90 at each junction 156a, these pieces of extra thickness 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 excess thickness pieces 90 are preferably attached to the sheet 144 in order to facilitate the manufacture of the sheet 144. For example, the excess thickness pieces 90 are attached to the sheet 144 by tacking. Even more preferably, the excess thickness pieces 90 are attached by tacking both to the flat portions 186 of the sheet 144 and to the corrugation portions 185a and / or 185b. Thus, it is ensured that the excess thickness pieces 90 are sufficiently attached to hold during handling of the sheets.

[0091] The manufacturing process has been described in the context of a sealed and thermally insulating tank for storing 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.

[0092] The manufacturing method has been described in the context of a tank wall produced according to the teaching of document WO 2023 / 198637 A1. The manufacturing method is however also applicable to any other tank wall in which a sealing membrane is produced by overlap welding corrugated metal sheets, in particular to a tank wall in which 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 comprising anchoring plates.Such a tank wall can be produced according to the teaching of document FR 2 691 520 A1, document WO 2014 / 057221 A2 or document WO 2017 / 006044 A1 for example. The sheets 44, 144 are anchored by their edges to the anchoring plates and not to the internal plates 42 described above.

[0093] With reference to the, a cutaway view of a ship 70 shows a sealed 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 appropriate connectors, to a maritime or port terminal to transfer a cargo of liquefied gas from or to the tank 71.

[0095] It also represents an example of a maritime terminal comprising a loading and unloading station 75, an underwater pipeline 76 and an onshore installation 77. The loading and unloading station 75 is a fixed offshore installation comprising a mobile arm 74 and a tower 78 which supports the mobile arm 74. The mobile arm 74 carries a bundle of insulated flexible pipes 79 which can be connected to the loading / unloading pipelines 73. The orientable mobile arm 74 adapts to all sizes of hydrogen carriers. A connecting pipe, not shown, extends inside the tower 78. The loading and unloading station 75 allows the hydrogen carrier 70 to be loaded and unloaded from or to the onshore installation 77. The latter comprises liquefied gas storage tanks 80 and connecting pipes 81 connected by the underwater pipe 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 makes it possible to keep the hydrogen carrier vessel 70 at a great distance from the coast during loading and unloading operations.

[0096] To generate the pressure necessary for the transfer of the liquefied gas, it is possible either to use pumps on board the ship 70 and / or pumps fitted to the onshore installation 77 and / or pumps fitted to the loading and unloading station 75 or to allow a rise in pressure in the interior 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 obvious that it is in no way limited thereto 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 "comprise", "comprise" or "include" and its conjugated forms does not exclude the presence of other elements or other steps than those set out in a claim.

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

Claims

A manufacturing method for manufacturing a sealing membrane for a tank wall for a sealed and thermally insulating tank for storing a liquefied gas, the manufacturing method comprising the following steps:- arranging 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 comprising two flat portions (186, 86) resting on the flat support surface and a corrugation portion (185a, 85a) formed between the two flat portions (186, 86), the corrugation portion (185a, 85a) projecting relative to the two flat portions (186, 86), the corrugation portion (185a) of the first metal sheet (144) and the corrugation 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 corrugation portion (185a) of the first metal sheet (144) extending to said edge (168) of the first metal sheet (144) and the corrugation portion (85a) of the second metal sheet (44) extending to said edge (68) of the second metal sheet (44), one end of the corrugation portion (85a) of the second metal sheet (44) covering one end of the corrugation 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) covering 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), andthe first metal sheet (144) carrying an excess thickness piece (90) located in line with at least a portion of the overlap zone (ZR) to thicken the first metal sheet (144) at least at junctions (156a) between the corrugation portion (185a) of the first metal sheet (144) and the two flat portions (186) of the first metal sheet (144);- making a continuous weld between the second metal sheet (44) and the first metal sheet (144) along the overlap zone (ZR), the continuous weld passing in line with the excess thickness piece (90)., Manufacturing method according to claim 1, wherein the excess thickness piece (90) extends continuously in a width of the corrugation 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). Manufacturing method according to claim 2, wherein the excess thickness part (90) is thicker at said junctions (156a) between the corrugation portion (185a) and the two flat portions (186) of the first metal sheet (144) than at a top portion (185at) of said corrugation portion (185a). Manufacturing method according to any one of claims 1 to 3, in which the excess thickness part (90) is attached to the two flat portions (186) of the first metal sheet (144). Manufacturing method according to any one of claims 1 to 4, in which the excess thickness part (90), the first metal sheet (144) and the second metal sheet (44) are made of the same metal alloy. A manufacturing method according to any one of claims 1 to 5, wherein the second metal sheet (44) comprises a groove (67) along said edge (68) of the second metal sheet (44). 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). 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 oversize piece (90) into a recess (429) in the support surface. A manufacturing method according to any one of claims 1 to 8, wherein the support surface is an inner surface of a thermally insulating barrier. 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 attached to an outer platen and an inner platen (42),the outer plates being fixed to the secondary thermally insulating barrier (12) and pressing the secondary sealing membrane (13) against the secondary thermally insulating barrier (12), the inner plates (42) forming said support surface, and wherein arranging the first metal sheet (144) and the second metal sheet (44) on the support surface comprises welding the first metal sheet (144) and the second metal sheet (44) to said inner plates (42)., 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) arranged on the flat support surface, the first metal sheet (144) and the second metal sheet (44) each comprising two flat portions (186, 86) resting on the flat support surface and a corrugation portion (185a, 85a) formed between the two flat portions (186, 86), the corrugation portion (185a, 85a) projecting relative to the two flat portions (186, 86), the corrugation portion (185a) of the first metal sheet (144) and the corrugation 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 corrugation portion (185a) of the first metal sheet (144) extending to said edge (168) of the first metal sheet (144) and the corrugation portion (85a) of the second metal sheet (44) extending to said edge (68) of the second metal sheet (44), one end of the corrugation portion (85a) of the second metal sheet (44) covering one end of the corrugation 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) covering 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) carrying an excess thickness piece (90) located in line with at least a portion of the overlap zone (ZR) to thicken the first metal sheet (144) at least at junctions (156a) between the corrugation portion (185a) of the first metal sheet (144) and the two flat portions (186) of the first metal sheet (144), in which the sealing membrane comprises a continuous weld between the second metal sheet (44) and the first metal sheet (144) along the overlap zone (ZR), the continuous weld passing in line with the excess thickness piece (90)., A vessel (70) for transporting a liquefied gas, the vessel comprising a double hull (72) and a tank (71) according to claim 11 disposed in the double hull. A transfer system for liquefied gas, the system comprising a vessel (70) according to claim 12, insulated pipes (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 for driving a flow of liquefied gas through the insulated pipes from or to the floating or land-based storage facility to or from the vessel tank. A method of loading or unloading a ship (70) according to claim 12, wherein a liquefied gas is conveyed through insulated pipes (73, 79, 76, 81) from or to a floating or land-based storage facility (77) to or from the tank (71) of the ship (70).

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