METHOD FOR TESTING THE SEALING OF A GASKETED MEMBRANE

Description

Domaine technique

[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 low-temperature liquefied gas, such as tanks for the transport of Liquefied Petroleum Gas (also called LPG) having, for example, a temperature between -50°C and 0°C, or for the transport of Liquefied Natural Gas (LNG) at approximately -162°C at atmospheric pressure. These tanks can be installed on land or on a floating structure. In the case of a floating structure, the tank can be intended for the transport of liquefied gas or for receiving liquefied gas used as fuel for the propulsion of the floating structure.

[0002] In one embodiment, the liquefied gas is LNG, namely a mixture with a high methane content stored at a temperature of approximately -162°C at atmospheric pressure. Other liquefied gases may also be considered, including ethane, propane, butane or ethylene, but also hydrogen. Liquefied gases may also be stored under pressure, for example at a relative pressure of between 2 and 20 bars, and in particular at a relative pressure of around 2 bars. The tank may be produced using various techniques, including in the form of an integrated membrane tank. Arrière-plan technologique

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

[0004] Document FR2903165 describes a sealed and thermally insulating tank in which prefabricated elements are anchored in the internal space of the supporting structure in order to form the tank. Each prefabricated element comprises a portion of secondary thermally insulating barrier, a portion of secondary waterproofing membrane and a portion of primary thermally insulating barrier. These prefabricated elements are anchored in a regular mesh on the supporting structure.

[0005] The primary thermally insulating barrier portion of a prefabricated block only partially covers the secondary waterproofing membrane. Thus, a peripheral portion of the secondary waterproofing membrane of said prefabricated blocks is visible. A flexible waterproof film is fixed on said peripheral portion of the secondary waterproofing membrane of two adjacent prefabricated elements in order to ensure the continuity of the secondary waterproofing membrane.

[0006] During the manufacturing of the tank, tests are carried out to ensure the watertightness of the secondary waterproofing membrane. In some cases, these watertightness tests must be carried out on portions of the tank only.

[0007] For example, in the case of a small tank such as a ship's fuel tank, the lower part of the tank is first assembled from prefabricated blocks and then scaffolding is installed to finalize the tank fabrication. It is then necessary to test the leaktightness of the secondary waterproofing membrane on the lower part of the tank while the tank is only partially fabricated.

[0008] Similarly, during the manufacture of an LNG tank, a side opening is blocked at the end of the tank's manufacture by adding a portion of the supporting structure on which a portion of the tank is mounted. It is then necessary to independently check the tightness of the secondary sealing membrane of the added portion of the tank.

[0009] However, such a leak test of the secondary sealing membrane of a portion of the tank is complex and requires numerous manipulations and checks. In particular, because this test is only carried out on an unfinished portion of the tank, the secondary sealing membrane does not form an enclosed leaktight space allowing a simple and direct leaktight test.

[0010] Document WO2014076424 describes a method for manufacturing a sealed and thermally insulated tank wall in which mechanically welded structures are used to form an enclosed space between a secondary sealing membrane and the supporting structure so as to test the leaktightness of the secondary sealing membrane. Such mechanically welded structures are complex to implement. Résumé

[0011] An idea underlying the invention is to provide a method for testing the leaktightness of a sealing membrane that is simple to implement. In particular, an idea underlying the invention is to provide such a leaktightness testing method for checking the leaktightness of the sealing membrane of an unfinished portion of a tank, i.e. of a portion of a tank intended to be associated with one or more other portions of a tank in order to finalize the manufacture of said tank. An idea underlying the invention is to enable this leaktightness test to be carried out reliably and quickly.

[0012] For this, the invention provides a method for testing the sealing of a sealing membrane, the sealing membrane being fixed to a thermally insulating barrier, the thermally insulating barrier resting on a sealed support surface, the method comprising: applying a first strip of waterproof sealant to the waterproofing membrane, applying a second strip of waterproof sealant to the supporting surface around the waterproofing membrane, arranging a waterproof cover on the first strip of waterproof sealant and on the second strip of waterproof sealant such that on the one hand the waterproof cover is tightly bonded to the waterproofing membrane by the first strip of waterproof sealant and on the other hand the waterproof cover is tightly bonded to the supporting surface by the second strip of waterproof sealant, the waterproof cover, the supporting surface, the first strip of waterproof sealant, the second strip of waterproof sealant and the waterproofing membrane jointly delimiting an enclosed space, putting the enclosed space under negative pressure relative to an environment outside said enclosed space;and measure a parameter representative of the change in pressure inside the enclosed space after the said enclosed space has been depressurized.

[0013] Thanks to these characteristics, it is possible to test the tightness of the waterproofing membrane of a portion of the tank during manufacture in a simple and reliable manner. In particular, the application of waterproof sealant strips and the arrangement of the waterproof cover in a watertight manner on the waterproofing membrane and on the supporting surface by means of the waterproof sealant strips makes it possible to create an enclosed space simply and quickly without requiring complex handling. In particular, this enclosed space is obtained without requiring welding of metal parts on the waterproofing membrane and / or on the supporting surface.

[0014] According to embodiments, such a leak testing method may include one or more of the following features.

[0015] A waterproof sealant strip can take various forms. It is advantageously supplied in the form of an unrolled roll for applying the waterproof sealant strip to the desired surface but can also, for example, be made from cartridges used with a sealant gun or be made from a loose material. Such a waterproof sealant strip is in an elongated form and is applied so as to surround a portion of the waterproofing membrane whose waterproofness is to be tested.

[0016] According to one embodiment, a waterproof sealant strip is for example an adhesive tape. According to one embodiment, the first waterproof sealant strip and / or the second waterproof sealant strip comprises a film and a layer of waterproof sealant on one side of said film. According to one embodiment, the layer of waterproof sealant is made of rubber, preferably synthetic rubber. According to one embodiment, the layer of waterproof sealant has a thickness of between 1 and 4 mm, for example 3 mm. According to one embodiment, the first waterproof sealant strip and / or the second waterproof sealant strip is produced by superimposing layers of waterproof sealant.

[0017] According to one embodiment, the waterproof mastic strip is made of butyl mastic, i.e. a plastic mastic based on polyisobutene.

[0018] Preferably, the rigid secondary barrier, otherwise designated by the acronym RSB (“Rigid Secondary Barrier”) or Triplex ®<, has a shear breaking stress, determined at -170°C according to the ISO4587 standard, of between 17 and 30 MPa and preferably greater than 22 MPa.

[0019] According to one embodiment, the waterproof mastic strip is a bead of adhesive waterproof mastic, for example waterproof mastic applied using a mastic gun or any other device making it possible to apply over the desired length a bead of waterproof mastic having the desired dimensions of length, thickness, section or other. According to one embodiment, the first waterproof mastic strip and / or the second waterproof mastic strip are made from a bead of mastic having a thickness of between 1 mm and 15 mm, preferably between 2 mm and 10 mm. Such a bead of mastic advantageously makes it possible to compensate for flatness defects in the support surface.

[0020] According to one embodiment, the first strip of waterproof mastic is fixed on a peripheral portion of the waterproofing membrane, said peripheral portion of the waterproofing membrane surrounding a central portion of the waterproofing membrane whose waterproofing is to be tested.

[0021] According to one embodiment, the waterproofing membrane comprises at least one portion of waterproof composite film, the method further comprising a step of applying an adhesive layer to one face of said at least one portion of composite film so that said adhesive layer impregnates the portion of composite film, the first strip of waterproof mastic being applied to said face of said at least one portion of composite film.

[0022] Such an adhesive layer impregnating the portion of waterproof composite film allows good cooperation between the first strip of waterproof mastic and the waterproofing membrane including at the level of the portion of waterproof composite film, in particular when this waterproof composite film is a flexible composite film as described below. Indeed, such a waterproof composite film may have irregularities, for example linked to the presence of visible fibers. These irregularities can degrade the waterproof cooperation between the first strip of waterproof mastic and the waterproofing membrane at the level of the waterproof composite film. Thus, such an adhesive layer impregnating the waterproof composite film adheres satisfactorily to the portion of waterproof composite film while providing a satisfactory adhesion and cooperation surface for the first strip of waterproof mastic.This is particularly interesting when the portion of waterproof flexible composite film has layers of unresined glass fibers to which the first strip of waterproof sealant does not adhere properly.

[0023] According to one embodiment, the adhesive layer is a layer of polyurethane glue.

[0024] According to one embodiment, the first strip of waterproof sealant is adhesive. According to one embodiment, the second strip of waterproof sealant is adhesive.

[0025] Such adhesive waterproof sealant strips facilitate the leak testing process. This is because such adhesive waterproof sealant strips ensure a simple and reliable leak-proof connection between said adhesive waterproof sealant strips and, on the one hand, the waterproofing membrane or the supporting surface and, on the other hand, the waterproof covering. In addition, such adhesive waterproof sealant strips can be fixed quickly, reliably and leak-proof to both the waterproofing membrane and the supporting surface.

[0026] According to one embodiment, the first strip of waterproof sealant is made of synthetic rubber. According to one embodiment, the second strip of waterproof sealant is made of synthetic rubber.

[0027] According to the invention, the waterproof cover is a polymer film tarpaulin.

[0028] According to one embodiment, the polymer film tarpaulin is made of a material selected from vinyl, nylon and polyethylene.

[0029] Such a polymer film tarpaulin is simple and quick to manufacture and size to form the waterproof cover. In addition, such a polymer film tarpaulin is simple to install while providing satisfactory waterproofing and resistance properties when depressurizing the enclosed space.

[0030] According to one embodiment, the method further comprises a step of positioning a screen covering a gap between the thermally insulating barrier and the support surface in order to prevent the polymer film sheet from positioning itself in said gap when the enclosed space is depressurized.

[0031] Such a screen makes it possible to obstruct a gap between the thermally insulating barrier and the support surface. Indeed, in the context of a tank integrated into a load-bearing structure such as a double hull of a ship, beads of mastic are generally inserted between the thermally insulating barrier and the support surface formed by the internal hull of the ship in order to compensate for flatness defects in the support structure. Thus, a space can separate the thermally insulating barrier from the support surface. Such a screen makes it possible to prevent the polymer film tarpaulin from degrading by inserting itself into this space when the enclosed space is depressurized.

[0032] According to one embodiment, the screen is a plate, for example made of plastic.

[0033] According to one embodiment, the method comprises a step of positioning a protective angle comprising a first flat wing and a second flat wing so that the first flat wing is arranged against the sealing membrane and the second flat wing runs along an edge of the thermally insulating barrier and projects towards the support surface.

[0034] According to one embodiment, the screen extends in the thickness direction of the tank wall, towards the interior of the tank, beyond the edge of the second flat wing of the protective angle. This makes it possible to prevent the polymer film sheet from coming into contact with an insulating lining of the thermally insulating barrier.

[0035] According to one embodiment, the screen comprises an angle iron resting on the one hand against the thermally insulating barrier and, on the other hand, against the support surface so as to form a flat bearing surface between the thermally insulating barrier and the support surface, the second strip of waterproof mastic being applied to the support surface so as to surround the angle iron so that said angle iron is housed in the enclosed space, the polymer film sheet being brought into contact with said flat bearing surface when said enclosed space is depressurized.

[0036] In one embodiment, a reinforcing fabric is secured to the polymer film tarpaulin, the tarpaulin being secured such that the reinforcing fabric is positioned in the enclosed space at an angle formed by the thermally insulating barrier.

[0037] Such a reinforcing fabric makes it possible to avoid degradation of the polymer film tarpaulin when the enclosed space is depressurized. Indeed, such a polymer film tarpaulin is relatively thin and may degrade when the enclosed space is depressurized, said depressurization of the enclosed space bringing the polymer film tarpaulin into contact with salient angles formed by the thermally insulating barrier. In addition, the lateral face of the thermally insulating barrier may have a certain roughness, for example when this lateral face of the thermally insulating barrier is formed by an insulating lining comprising reinforcing fibers. Such roughness is also likely to degrade the polymer film tarpaulin when the enclosed space is depressurized. This reinforcing fabric thus makes it possible to protect the polymer film tarpaulin when the enclosed space is depressurized.

[0038] According to one embodiment, the thermally insulating barrier comprises a plurality of prefabricated blocks juxtaposed in a regular pattern. According to one embodiment, the waterproofing membrane comprises a plurality of portions of rigid waterproof film, each portion of rigid waterproof film being integrated into a corresponding prefabricated block. According to one embodiment, a portion of rigid waterproof film, preferably each portion of rigid waterproof film, comprises an aluminum foil interposed between two layers of glass fibers and resin, such a rigid waterproof film being sold in particular under the name Triplex ®< rigid. According to one embodiment, the waterproofing membrane comprises one or more portions of flexible and waterproof composite film.According to one embodiment, said portion(s) of flexible composite film are fixed in a sealed manner, for example by gluing, to portions of rigid waterproof film of two adjacent prefabricated blocks. According to one embodiment, the portion(s) of flexible composite film comprise an aluminum foil interposed between two layers of non-resinated glass fibers, such a portion of flexible composite film being marketed in particular under the name Triplex ®< flexible. According to one embodiment, the portion of waterproof composite film on which the adhesive layer is applied is a portion of flexible composite film.

[0039] According to one embodiment, the first strip of waterproof sealant is applied to the waterproofing membrane after the waterproofing membrane has been fixed to the insulating thermal barrier.

[0040] In one embodiment, the first strip of waterproof sealant is applied directly against the rigid waterproof film.

[0041] In one embodiment, the first strip of waterproof sealant is applied indirectly via an adhesive layer to the flexible waterproof film.

[0042] According to one embodiment, the method further comprises the steps of removing the waterproof cover, removing the first strip of waterproof mastic and removing the second strip of waterproof mastic after the step of measuring the parameter representative of the change in pressure in the enclosed space. According to one embodiment, the method further comprises a step of sanding the adhesive layer. This sanding of the adhesive layer makes it possible to remove any pollution resulting from the application of the adhesive layer to the waterproofing membrane.

[0043] According to an embodiment not covered by the claims, the waterproof cover comprises a waterproof metal structure.

[0044] Such a metal structure has good reliability during the sealing test while allowing sealing of the enclosed space in a simple and rapid manner by arranging said metal structure on the waterproof sealant strips. Furthermore, such a metal structure has a weight allowing its sealing cooperation with the waterproof sealant strips in a simple and effective manner.

[0045] According to an embodiment not covered by the claims, the metal structure comprises a central portion, a flat internal rim, and a flat external rim, and the flat inner edge develops in a first plane parallel to the waterproofing membrane and the flat outer edge develops in a second plane parallel to the support surface, and the waterproof cover is arranged so that the first strip of waterproof mastic is sealingly interposed between the flat inner edge and the waterproofing membrane and so that the second strip of waterproof mastic is sealingly interposed between the flat outer edge and the support surface.

[0046] According to an embodiment not covered by the claims, the metal structure is made of stainless steel.

[0047] According to an embodiment not covered by the claims, the central portion is planar. According to one embodiment, the central portion develops in a plane parallel to the thickness direction of the tank wall.

[0048] According to an embodiment not covered by the claims, the internal rim develops in a first plane and the external rim develops in a second plane, the first plane and the second plane forming an angle corresponding to the angle between the waterproofing membrane and the support surface.

[0049] According to an embodiment not covered by the claims, the planar internal rim develops perpendicular to the planar central portion. According to one embodiment, the planar external rim develops perpendicular to the planar central portion. According to one embodiment, the planar internal rim develops from a first edge of the planar central portion on a first side of said planar central portion and the planar external rim develops from a second edge of the planar central portion on a second side of the planar central portion, the first edge of the planar central portion being opposite the second edge of the planar central portion, the first side of the planar central portion being opposite the second side of the planar central portion.

[0050] According to an embodiment not covered by the claims, a plurality of metal structures as above are arranged between the waterproofing membrane and the supporting surface, additional strips of waterproof mastic being arranged in a sealed manner between two successive metal structures of the waterproof cover.

[0051] According to an embodiment not covered by the claims, the metal structure comprises an internal part and an external part, the internal portion comprising the flat internal rim and a first part of the central portion, the external part comprising the flat external rim and a second part of the central portion, and the step of arranging the waterproof cover comprises the steps of: arranging the first part of the metal structure so that the flat inner edge rests on the first strip of waterproof sealant, arranging the second part of the metal structure so that the flat outer edge rests on the second strip of waterproof sealant, and sealingly bonding the first part of the metal structure and the second part of the metal structure.

[0052] Such a two-part metal structure advantageously makes it possible to compensate for deviations related to manufacturing tolerances of the tank portion and / or parts of the metal structure. In particular, the first part and the second part of the central portion may overlap more or less to form the central portion and thus compensate for deviations resulting from manufacturing tolerances of the metal structure or the thermally insulating barrier or even flatness defects of the support surface.

[0053] The first portion of the metal structure and the second portion of the metal structure can be tightly connected in many ways. In one embodiment, the first portion of the metal structure and the second portion of the metal structure are tightly connected by welding. In one embodiment, the first portion of the metal structure and the second portion of the metal structure are tightly connected by a strip of waterproof sealant.

[0054] According to one embodiment, the method further comprises a step of applying a bearing force towards the support surface on the waterproof cover in line with the first strip of waterproof mastic and in line with the second strip of waterproof mastic.

[0055] The application of such a bearing force on the waterproof cover at the level of the waterproof mastic strips ensures good cooperation and good sealing between the waterproof cover and the waterproofing membrane and / or the supporting surface.

[0056] According to one embodiment, the method further comprises a step of fixing a counter-form at a corner of the thermally insulating barrier so that said counter-form covers said corner, the counter-form being connected in a sealed manner on the one hand to the support surface and, on the other hand, to the secondary sealing membrane.

[0057] According to one embodiment, the waterproof cover comprises the counter-form. According to one embodiment, the counter-form is housed in the enclosed space.

[0058] According to one embodiment, the counter-form is a metal part, for example made of stainless steel. The counter-form can be fixed in many ways to the waterproofing membrane or to the support surface. According to one embodiment, the counter-form is welded to the support surface. According to one embodiment, the counter-form is tightly connected to the support surface and / or to the waterproofing membrane by means of a waterproof mastic strip such as the first waterproof mastic strip and / or, respectively, the second waterproof mastic strip.

[0059] According to one embodiment, the angle covered by the counter-form is a salient angle of the thermally insulating barrier.

[0060] According to one embodiment, the angle has an edge developing along a thickness direction of the tank, the counter-form having a first flat wing covering a portion of a first lateral face of the thermally insulating barrier and a second flat wing covering a portion of a second lateral face of the thermally insulating barrier, said portions of the first lateral face and of the second lateral face of the thermally insulating barrier forming said angle of the thermally insulating barrier. According to one embodiment, the counter-form has a third wing developing in a plane perpendicular to the thickness direction of the tank, said third wing being connected in a sealed manner to the sealing membrane.

[0061] According to one embodiment, the counter-form is manufactured by in situ molding on the angle of the thermally insulating barrier.

[0062] According to one embodiment, the method comprises a step of positioning a connection device comprising a connection angle and a connection flange arranged opposite an orifice provided in said connection angle, said connection angle being connected in a sealed manner to the support surface, to the sealing membrane and to the waterproof cover and the connection flange being connected in a sealed manner to a means for creating a vacuum in the enclosed space.

[0063] According to one embodiment, the connecting angle is manufactured by in situ molding on the thermally insulating barrier, the connecting flange being taken from the mass of the connecting angle during its molding.

[0064] According to one embodiment, the invention also provides a sealing device for closing an enclosed space defined between a sealing membrane fixed on a thermally insulating barrier anchored to a support surface and said support surface; the sealing device comprising a waterproof cover tightly bonded to, on the one hand, the waterproofing membrane by means of a first strip of waterproof mastic and, on the other hand, to the support surface by means of a second strip of waterproof mastic, and a vacuum pump connected to the enclosed space and capable of putting said enclosed space under vacuum.

[0065] Such a sealing device makes it possible to test the sealing of a portion of a tank simply, quickly and reliably.

[0066] According to embodiments, such a sealing device may comprise one or more of the aforementioned features or the following features.

[0067] According to the invention, the waterproof cover comprises a polymer film tarpaulin, the sealing device further comprising a screen covering a gap between the thermally insulating barrier and the support surface so as to obstruct said gap and prevent the insertion of the polymer film tarpaulin into said gap in the presence of a depression in the enclosed space.

[0068] According to one embodiment, the sealing device further comprises a clamping device arranged to exert a bearing force towards the support surface on the waterproof cover in line with the first and second waterproof mastic strips.

[0069] Applying such a pressing force to the waterproof cover in line with the waterproof mastic strips ensures good cooperation and good sealing of the fixing of the waterproof cover to the waterproof mastic strips.

[0070] According to one embodiment, the clamping device comprises a fixing member fixed to the support surface and a support plate, the support plate being mounted movably in a thickness direction of the tank on the fixing member so as to be able to be brought into contact with the waterproof cover at the level of the second strip of waterproof mastic.

[0071] According to one embodiment, the prefabricated blocks comprise a portion of primary thermally insulating barrier resting on the rigid waterproof film. According to one embodiment, said portions of thermally insulating barrier have dimensions smaller than the dimensions of the rigid waterproof film so that a periphery of said rigid waterproof film is visible.

[0072] According to one embodiment, the clamping device comprises a support member fixed to the primary thermally insulating barrier portion of a prefabricated block.

[0073] According to one embodiment, the waterproofing membrane is a corrugated waterproofing membrane comprising a first series of parallel corrugations and a second series of parallel corrugations, the corrugations of the first series of parallel corrugations and the corrugations of the second series of parallel corrugations being intersecting, the waterproofing membrane comprising a plurality of nodes formed at the intersections between the corrugations of the first series of parallel corrugations and the corrugations of the second series of parallel corrugations. According to one embodiment, the clamping device comprises a support member fixed to the waterproofing membrane, for example by clipping onto undercuts formed by the nodes of the waterproofing membrane.

[0074] According to one embodiment, said support member has a base fixed to said portion of primary thermally insulating barrier, for example on one of said nodes of the waterproofing membrane, a spacer extending from said base in the direction of the rigid waterproof film and a support plate mounted to move in the direction of thickness of the tank on the spacer so as to be able to exert a support force on the waterproof cover at right angles to the first strip of waterproof mastic.

[0075] According to one embodiment, the support surface is formed by a supporting structure intended to receive a sealed and thermally insulating tank comprising the sealing membrane whose sealing is to be tested, for example by the internal hull of a ship comprising said tank.

[0076] According to one embodiment, the support surface is formed by the secondary sealing membrane of a sealed and thermally insulating tank, the sealing membrane to be tested then being a primary sealing membrane.

[0077] Such a leak testing method or leak detection device may be implemented in a tank that may be part of a land-based storage facility, for example for storing LNG, or installed in a floating, coastal, or deep-water structure, including an LNG carrier, a floating storage and regasification unit (FSRU), a floating production and offshore storage unit (FPSO), and others. Such a tank may also serve as a fuel tank in any type of vessel. Brève description des figures

[0078] 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. [ fig.1 ] there figure 1 is a schematic perspective view of a portion of a sealed and thermally insulating tank. fig.2 ] there figure 2 is a sectional view of the sealed and thermally insulating tank portion of the figure 1 on which a sealing device is installed according to a first embodiment. fig.3 ] there figure 3 is a sectional view of the sealed and thermally insulating tank portion of the figure 1 on which is installed a sealing device according to a first variant of the first embodiment illustrated in the figure 2 . [ fig.4 ] there figure 4 is a sectional view of the sealed and thermally insulating tank portion of the figure 1 on which is installed a sealing device according to a second variant of the first embodiment illustrated in the figure 2 . [ fig.5 ] there figure 5 is a schematic perspective view of a portion of a sealed and thermally insulating tank whose sealing membrane is to be tested for leaktightness. fig.6 ] there figure 6 is a schematic perspective view of the tank portion shown in detail in the figure 5 during a first step of implementing a leak testing method using a sealing device according to a second embodiment not covered by the claims. fig.7 ] there figure 7 is a schematic perspective view of the tank portion shown in detail in the figure 5 during a second step of implementing the leak testing method using the sealing device according to the second embodiment. fig.8 ] there figure 8 is a schematic perspective view of the tank portion shown in detail in the figure 5 during a third step of implementing the leak testing method using the sealing device according to the second embodiment. fig.9 ] there figure 9 is a schematic perspective view of the tank portion shown in detail in the figure 5 during a fourth step of implementing the leak testing method using the sealing device according to the second embodiment. fig.10 ] there figure 10 is a schematic perspective view of the tank portion shown in detail in the figure 5 during a fifth step of implementing the leak testing method using the sealing device according to the second embodiment. fig.11 ] there figure 11 is a schematic perspective view of the tank portion shown in detail in the figure 5 on which the sealing device is installed according to the second embodiment. fig.12 ] there figure 12 is a sectional view of the sealed and thermally insulating tank portion of the figure 1 on which is installed a sealing device according to another variant of the first embodiment illustrated in the figure 2 . [ fig.13 ] there figure 13 is a perspective view of a connection device during its manufacture by in-situ molding on the secondary thermally insulating barrier. Description des modes de réalisation

[0079] In the remainder of the description, the terms "external" and "internal" will be used to designate, according to the definitions given in the description, the relative position of one element with respect to another, with reference to the interior of the tank. Thus, an element close to or facing the interior of the tank is described as internal as opposed to an external element located close to or facing the exterior of the tank.

[0080] In relation to the figure 1 , we observe a portion of a sealed and thermally insulating tank anchored on a supporting structure 13. Such a portion of tank comprises, from the outside of the tank towards the inside of the tank, a secondary thermally insulating barrier 1, a secondary sealing membrane 2, a primary thermally insulating barrier 3 and a primary sealing membrane (not illustrated in the figure 1 ).

[0081] The tank is manufactured from prefabricated blocks 4 each comprising a portion of secondary thermally insulating barrier, a portion of secondary sealing membrane and a portion of primary thermally insulating barrier. More particularly, each prefabricated block 4 comprises, from the outside of the tank to the inside of the tank, a base plate 5, a secondary insulating lining 6, a rigid waterproof film 7, a primary insulating lining 8 and a cover plate 9. The base plate 5 and the secondary insulating lining 6 form a first block of substantially parallelepipedal shape covered by the rigid waterproof film 7 and the primary insulating lining 8 and the cover plate 9 form a second block of substantially parallelepipedal shape resting on the rigid waterproof film 7.

[0082] The base plate 5 and the cover plate 9 are, for example, made of plywood. The secondary insulating lining 6 and the primary insulating lining 8 are, for example, made of polyurethane foam, possibly reinforced with fibers. The rigid waterproof film 7 is, for example, made of rigid triplex ®<, i.e., made of an aluminum foil sandwiched between two layers of glass fibers and resin.

[0083] In such a prefabricated block 4, the bottom plate 5, the secondary insulating lining 6 and the rigid waterproof film 7 have dimensions in a plane perpendicular to the thickness direction of the tank greater than the dimensions of the primary insulating lining 8 and the cover plate 9 so that a peripheral edge 10 of the rigid waterproof film is not covered by the primary insulating lining 8.

[0084] During the manufacture of the tank, such prefabricated blocks 4 are anchored on the supporting structure 13, for example the internal wall of a double hull of a ship, in a juxtaposed manner. A flexible waterproof film 11 is applied to the peripheral edge 10 of the rigid waterproof film 7 of two juxtaposed prefabricated blocks 4 so as to ensure continuity of the sealing between the rigid waterproof films 7 of two adjacent prefabricated blocks 4. This flexible waterproof film 11 is for example made of flexible triplex ®<, that is to say comprising an aluminum sheet between two layers of non-resinized glass fibers. The secondary waterproofing membrane 2 is formed by the rigid waterproof film 7 of these two prefabricated blocks 4 and a portion of flexible waterproof film 11 connecting the adjacent peripheral edge portions 10 of said two prefabricated blocks 4.Other details on such prefabricated blocks 4, their arrangement, or other constituent elements of the tank are for example described in document FR2903165.

[0085] During the manufacture of the tanks, it is necessary to test the tightness of the secondary waterproofing membrane 2 during manufacture.

[0086] This is for example the case in small tanks such as tanks intended to serve as fuel tanks supplying a propulsion system. Indeed, these tanks are likely to be assembled in two stages, a lower part of the tank being assembled on the supporting structure 13 in a first stage then, in a second stage and after installation of scaffolding, the upper part of the tank is assembled on the supporting structure 13. It is necessary to test the good sealing of the secondary sealing membrane 2 prior to the installation of the upper part of the tank. However, when only the lower part of the tank is assembled, the secondary sealing membrane 2 is only partially formed and the peripheral edge 10 is visible on the prefabricated blocks which constitute the ends of said lower part of the tank.

[0087] This is also the case when closing the tank in the context of an LNG tank. Indeed, during the manufacture of an LNG tank, a lateral portion of the supporting structure 13, and therefore of the corresponding tank, is left open in order to allow the passage of the tools necessary for the construction of the tank. This opening, generally called a hull breach, is closed to finalize the construction of the tank by adding a portion of the supporting structure 13 on which a corresponding portion of the tank is mounted. The portion of the tank mounted on the added portion of the supporting structure 13 comprises prefabricated blocks 4 and has a peripheral edge 10 of exposed secondary sealing membrane 2. The sealing of the secondary sealing membrane 2 formed by this added portion of the tank must also be tested prior to finalizing the manufacture of the tank.

[0088] In order to test the tightness of the secondary waterproofing membrane 2 in a tank during manufacture, a tightness testing device is provided. figures 2 à 4 illustrate a first embodiment of such a leak testing device.

[0089] In the example illustrated on the figure 1 , only two prefabricated blocks 4 are illustrated. The remainder of the description of this first embodiment of the leak testing device is carried out within the framework of a portion of tank formed by these two prefabricated blocks 4 and the portion of flexible leakproof film 11 connecting said prefabricated blocks 4. However, this description applies by analogy to any set of prefabricated blocks 4 anchored on the supporting structure and connected at their adjacent edges by portions of flexible leakproof film 11.

[0090] Such a portion of tank has a central portion 14 of secondary waterproofing membrane 2 whose waterproofness must be tested. This central portion 14 is formed by the rigid waterproof films 7 of the adjacent prefabricated blocks 4 and the portions of flexible waterproof film 11 connecting said prefabricated blocks 4. This central portion 14 is surrounded by a peripheral portion 15 of secondary waterproofing membrane 2. This peripheral portion 15 is formed on the one hand by the peripheral edge portions 10 located at the face of prefabricated blocks 4 without a prefabricated block 4 facing each other and, on the other hand, by end portions 16 of the portions of flexible waterproof film 11 connecting said peripheral edge portions 10.

[0091] There figure 2 illustrates a sectional view of a portion of the tank being manufactured on which is installed a device for testing the tightness of the secondary waterproofing membrane according to the first embodiment. Typically, this figure 2 illustrates a sectional view of the prefabricated blocks 4 at the level of section plane AA of the figure 1 . The function of this leak testing device is to enable the leak testing of the central portion 14 of the secondary sealing membrane 2 formed by the two prefabricated blocks 4 as well as by the portion of flexible waterproof film 11 sealingly connecting the facing portions of the peripheral edges 10 of the two prefabricated blocks 4.

[0092] According to this first embodiment, the leak testing device comprises a polymer film tarpaulin 12 fixed in a leaktight manner on the one hand to the secondary sealing membrane 2 and, on the other hand, to the supporting structure 13 by means of strips of leaktight mastic.

[0093] A first adhesive strip of waterproof mastic 17 is applied to the rigid waterproof film 7. More particularly, this first adhesive strip of waterproof mastic 17 is applied in a waterproof manner to the peripheral portion 15 of the waterproofing membrane 2, that is to say to the entire periphery of the secondary waterproofing membrane 2 entirely surrounding the central portion 14 of the secondary waterproofing membrane 2 to be tested.

[0094] A second strip of adhesive waterproof mastic 18 is applied directly to the supporting structure 13. More particularly, this second strip of adhesive waterproof mastic 18 is applied in a sealed manner to the supporting structure 13 so as to completely surround the portion of the tank whose sealing of the secondary sealing membrane 2 is to be tested.

[0095] The polymer film sheet 12 is applied in a sealed manner to the first adhesive waterproof sealant strip 17. Similarly, the polymer film sheet 12 is applied in a sealed manner to the second adhesive waterproof sealant strip 18. Typically, the polymer film sheet 12 sealably connects the secondary waterproofing membrane 2 covered by the first waterproof sealant strip 17 and the supporting structure 13 at the second waterproof sealant strip 18. Thus, an enclosed space 19 is jointly delimited by the portion 20 of the supporting structure 13 surrounded by the second waterproof sealant strip 18, the polymer film sheet 12 and the central portion 14 of the secondary waterproofing membrane 2 surrounded by the first waterproof sealant strip 17.

[0096] The first strip of waterproof sealant 17 and the second strip of waterproof sealant 18 are preferably made of synthetic rubber. For example, the strips of waterproof sealant 17, 18 are presented in the form of adhesive waterproof sealant ribbons having a thickness of adhesive synthetic rubber of between 1 and 4 mm, for example 3 mm, carried by a film of PTFE polyester or other, the ribbon being unrolled by applying the face carrying the waterproof sealant to the application surface and removing the film once the waterproof sealant has been applied to said surface. Such waterproof sealant ribbons 17, 18 based on synthetic rubber adhesive are for example produced by the company Airtech ®< , for example under the name AT-200Y. The sealant is for example a butyl sealant, that is to say a plastic sealant based on polyisobutene. Such a sealant has a viscosity at rest and at 25°C of between 735,000 and 805,000 Pa.s, for example of the order of 770,000 Pa.s.and a viscosity at 25°C of between 180,000 and 250,000 Pa.s, for example of the order of 215,000 Pa.s when stressed at a shear rate of 0.6 s -1< . Furthermore, such a sealant has a shear breaking stress, determined at -170°C according to the ISO4587 standard, of between 17 and 30 MPa and preferably greater than 22 MPa. Finally, it has been observed that such a sealant has excellent adhesion properties.

[0097] The polymer film cover 12 is for example made of vinyl film or nylon, such as for example a cover produced by the company Airtech ®< under the name Wrightlon ®< . Such a nylon cover has for example a thickness of between 50 and 100 µm, for example of the order of 70 µm. According to another embodiment, the polymer film cover 12 is made of polyethylene and preferably has a thickness of between 150 and 240 µm, for example of the order of 190 µm. Such a polymer film cover 12 is waterproof and can be fixed in a waterproof manner in a reliable and simple manner by means of a strip of waterproof adhesive mastic 17, 18 as described above. In addition, such a polymer film cover 12 can easily be sized according to the dimensions of the portion of the tank whose waterproofing of the secondary waterproofing membrane 2 is to be tested.

[0098] To check the tightness of the fixing of the first strip of waterproof mastic 17 on the secondary waterproofing membrane 2, of the second strip of waterproof mastic 18 on the supporting structure 13 and of the polymer film tarpaulin 12 on said adhesive strips of waterproof mastic 17, 18, it is for example possible to use an acoustic leak detection system, such as for example an ultrasonic leak detection system, after having previously depressurized the enclosed space 19. Such an ultrasonic leak detection system is for example of the Vacleak LEQ-70 ®< type which is produced by the company Airtech ®< .

[0099] In order to test the tightness of the secondary waterproofing membrane 2 to be tested, i.e. the central portion 14 surrounded by the first strip of waterproof mastic 17, the polymer film tarpaulin 12 is connected to a vacuum means. Such a vacuum means is for example a vacuum pump 31 connected to the enclosed space 19 or any other vacuum means capable of reducing the pressure in the enclosed space 19.

[0100] Activation of the depression means makes it possible to reduce the pressure in the enclosed space 19 relative to the environment outside said enclosed space 19. This depression is, for example, of the order of -500 to -600 mbars.

[0101] In order to detect a possible defect in the sealing of the secondary sealing membrane 2, the evolution of a parameter representative of the pressure in the enclosed space 19 is then monitored by means of an ad hoc sensor, for example a sensor integrated into the vacuum pump 31. This parameter may be, for example, the pressure measured in the enclosed space by a pressure sensor 32, a tension parameter of the polymer film sheet 12 under the effect of the depression in the enclosed space 19, an acoustic parameter or any other parameter making it possible to measure the evolution of the pressure in the enclosed space 19. In the event of an increase in the pressure in the enclosed space 19 relative to the environment outside said enclosed space 19, then a defect in the sealing of the secondary sealing membrane 2 tested is detected.

[0102] The portion of flexible waterproof film 11 has a roughness greater than the portion of rigid waterproof film 7. In fact, the portion of flexible waterproof film 11 of the Triplex ®< flexible type has visible fibers which impair the waterproof adhesion of the first strip of adhesive waterproof mastic 17 on said portion of flexible waterproof film 11

[0103] In order to ensure the sealed cooperation between the flexible waterproof film portion 11 and the first strip of waterproof sealant 17, a layer of polyurethane glue 21 is applied to the end portions 16 of the flexible waterproof film portion 11 intended to receive the first strip of waterproof sealant 17. This layer of polyurethane glue 21 penetrates the flexible waterproof film portion 11, thus ensuring good cooperation between said layer of polyurethane glue 21 and the flexible waterproof film portion 11. This layer of polyurethane glue 21 further provides a good adhesion surface for the first strip of waterproof sealant 17, thus ensuring the sealed and reliable fixing of said first strip of waterproof sealant 17 on the flexible waterproof film portion 11. In order to ensure good impregnation of the polyurethane layer 21 in the flexible waterproof film 11, the layer of polyurethane glue 21 is advantageously heated and pressed.After the sealing test, the layer of polyurethane glue 21 is preferably sanded in order to avoid the presence of polyurethane glue residues on the portion of flexible waterproof film 11. Similarly, after the sealing test, a check is preferably carried out, for example a simple visual check by an operator, of the absence of residues of the first strip of waterproof mastic 17, and possibly of the second strip of waterproof mastic 18.

[0104] There figure 3 illustrates a first variant of the first embodiment of the leak testing device. This first variant differs from that described with respect to the figure 2 in that the leak testing device further comprises a screen-forming corner 22 and a reinforcing fabric 23.

[0105] When the enclosed space 19 is depressurized, the polymer film sheet 12 is brought under the effect of the depression into contact and into abutment against the secondary thermally insulating barrier 1. In particular, the polymer film sheet 12 is brought into contact with the salient angle formed by the secondary thermally insulating barrier 1. A relatively thin polymer film sheet 12 could thus deteriorate upon contact with the salient angle formed by the secondary thermally insulating barrier 1.

[0106] In this first variant, the reinforcing fabric 23 is positioned so as to cover the protruding angle formed by the secondary thermally insulating barrier 1 and thus protect the polymer film tarpaulin 12 when the enclosed space 19 is depressurized.

[0107] Similarly, the insulating lining 6 of the secondary thermally insulating barrier 1 may have a high roughness, in particular when this insulating lining 6 is formed of fiber-reinforced foam. This roughness of the insulating lining 6 may also degrade the polymer film sheet 12 when the enclosed space 19 is depressurized, said depressurization of the enclosed space bringing the polymer film sheet into contact with the secondary insulating lining 6. Thus, the reinforcing fabric 23 advantageously covers the lateral faces of the prefabricated blocks 4 so as to protect the polymer film sheet 12 when the enclosed space 19 is depressurized.

[0108] Such a reinforcing fabric 23 is installed, for example by being fixed or deposited on the secondary thermally insulating barrier 1 at the locations likely to degrade the polymer film cover 12. This reinforcing fabric can also be directly integrated into the polymer film cover 12, for example by gluing, and the polymer film cover is then fixed to form the enclosed space so that this reinforcing fabric 23 is arranged at the desired locations of the secondary thermally insulating barrier 1 when the enclosed space 19 is depressurized. Such a reinforcing fabric 23 can be made of numerous materials such as cardboard, wood, plastic or other materials making it possible to protect the polymer film cover 12.

[0109] Furthermore, when the prefabricated blocks 4 are anchored on the supporting structure 13, a gap 24 remains present between the bottom plate 5 of said prefabricated blocks 4 and the supporting structure 13. This gap results from the presence of beads of mastic between the bottom plate 5 of the prefabricated blocks 4 and the supporting structure 13. Such beads of mastic make it possible to compensate for the flatness defects of the supporting structure 13 and offer a flat support surface for anchoring the prefabricated blocks 4.

[0110] The angle iron 22 is installed around the portion of the tank for which the leaktightness of the secondary sealing membrane 2 is to be tested. The angle iron 22 is positioned along the secondary thermally insulating barrier 1 so as to obstruct the gap separating the prefabricated blocks 4 and the supporting structure 13. Typically, this angle iron 22 has a flat plate extending from the supporting structure 13 towards the inside of the tank at least as far as the bottom plate 5 of the prefabricated blocks 4. This flat plate thus provides a continuous and flat support surface around the portion of the tank for which the leaktightness of the secondary sealing membrane 2 is to be tested.When the enclosed space 19 is depressurized, the polymer film sheet 12 is brought under the effect of the depression into the enclosed space 19 to bear against this flat surface formed by the angle iron 22 and cannot be inserted into the interstices separating the prefabricated blocks 4 and the supporting structure 13, such insertion being able to damage the polymer film sheet 12.

[0111] Similarly and not shown, a sealing means may be provided between two lateral faces of adjacent prefabricated blocks 4 to prevent damage to the polymer film cover 12 under the effect of the depression in the enclosed space 19. This sealing means is for example produced by covering the spaces between the adjacent prefabricated blocks 4 with the reinforcing fabric 23, a flat plate or any other suitable means. Thus, this sealing means may also be produced using insulating packing plugs inserted between the prefabricated blocks.

[0112] In another embodiment shown in the figure 12 , the sealing device comprises a plate 34, for example made of plastic material, such as PVC, which makes it possible to protect the polymer film tarpaulin 12, during the depression, by preventing it from coming into contact with the insulating lining 6 and from being inserted into the interstices separating the prefabricated blocks 4 and the supporting structure 13.

[0113] Furthermore, in this embodiment, the sealing device comprises a protective angle 35 which is positioned along the secondary thermally insulating barrier 1. The protective angle 35 comprises a first flat wing which extends parallel to the supporting structure 13 and is fixed against the rigid waterproof film 7 and a second flat wing which extends in the direction of thickness of the tank wall, in the direction of the supporting structure 13 and is positioned against the lateral faces of the prefabricated blocks 4. The protective angle 4 is, for example, made of cardboard and makes it possible to protect the polymer film cover 12 from the protruding angles of the secondary thermally insulating barrier 1.

[0114] Advantageously, the plate 34 extends in the thickness direction of the tank wall, towards the inside of the tank, beyond the edge of the second flat wing of the protective angle iron 35, which makes it possible to prevent the polymer film sheet 12 from coming into contact against the insulating lining 6.

[0115] There figure 4 illustrates a second variant of the first embodiment of the leak testing device. This second variant differs from that described with respect to the figure 2 in that the leak testing device further comprises a complementary clamping device 25 to ensure the leaktight fixing of the polymer film sheet 12 on the supporting structure 13 and on the secondary sealing membrane 2.

[0116] Such a clamping device 25 comprises studs 26 fixed to the supporting structure 13. Support plates 27 are mounted on these studs 26 by any suitable means. For example, such a stud 26 comprises a rod whose end is threaded. The support plate 27 has a through hole and is mounted on the stud 26 so that the rod of said stud passes through the through hole of the support plate 27. A nut (not shown) is screwed onto the threaded end of the rod so as to press the support plate 27 towards the supporting structure 13. Such a support plate 27 is for example a wooden cleat and is positioned so as to be brought into abutment against the polymer film sheet 12 in line with the second strip of waterproof mastic 18 when the nut is screwed on.

[0117] The clamping device 25 further comprises a support member comprising a base 28, a spacer 29 and a support plate 30. The base 28 is fixed to the primary thermally insulating barrier 3. For example, the base 28 is fixed to the fixing points which are usually used to fix additional panels used to complete the primary thermally insulating barrier 3 during the manufacture of the tank. The spacer 29 develops from the base 28 in the direction of the secondary waterproofing membrane 2. One end of the spacer 29 opposite the base 28 carries the support plate 30 which is arranged in line with the first strip of waterproof mastic 17 and rests on the polymer film sheet 12 in line with the first strip of waterproof mastic 17.The support of said support plate 30 is adjustable by any suitable means, for example the spacer 29 can be telescopic with a locking system making it possible to adjust the size of the spacer 29 or the spacer 29 can comprise a thread cooperating with a nut which, when threaded, brings the support plate 30 into support on the polymer film cover 12 or other.

[0118] At the corners of the portion of the tank for which the sealing of the secondary sealing membrane 2 is to be tested, for example at the corners of the tank as finished, the polymer film sheet 12 may have folds in order to follow the geometry of the portion of the tank at said corner.

[0119] Alternatively, a plurality of polymer film sheeting pieces 12 may be joined together using an additional adhesive sealing mastic strip (not shown).

[0120] According to another alternative, a counter-form 33 illustrated on the figure 1 can be fixed in a sealed manner to cover the angle. This counter-form 33 comprises a first flat wing, a second flat wing and a third flat wing. The first flat wing develops in a plane parallel to the thickness direction of the tank and covers an end portion of a first lateral face of the secondary thermally insulating barrier 1. The second flat wing develops in a plane parallel to the thickness direction of the tank and covers an end portion of a second lateral face of the secondary thermally insulating barrier 1, the first end portion and the second end jointly forming a salient angle of the secondary thermally insulating barrier 1.The third wing develops in a plane perpendicular to the direction of thickness of the tank and covers a portion of secondary sealing membrane directly above said end portions of the first and second lateral faces of the secondary thermally insulating barrier 1. This counter-form 33 is for example made of stainless steel and is fixed in a sealed manner by means of adhesive waterproof mastic strips such as described above applied between the third wing and the secondary sealing membrane 2 and between the first and second wings and the supporting structure 13.

[0121] In this alternative, the polymer film sheet 12 may cover the corner counter-form 33 or be fixed in a sealed manner to said counter-form 33 by one or more additional adhesive waterproof mastic strips similar to the first and / or second adhesive waterproof mastic strip.

[0122] According to another alternative, not illustrated, the counter-form 33 is produced by in-situ molding at the corners of the thermally insulating barrier, which makes it possible to obtain a custom-made counter-form 33. The counter-form 33 is, for example, produced by molding polyurethane glue. To do this, the corner area intended to receive the counter-form molded in situ is first covered with a protective adhesive strip to prevent the polyurethane glue from coming into direct contact with the secondary waterproofing membrane 2 or the secondary thermally insulating barrier 1. The protective adhesive strip is preferably made of silicone and acrylic for the adhesive part while the strip part (non-adhesive function but support for the adhesive and mechanical strength) is made of polyester, with a thickness of between 150 and 200 µm, preferably between 155 and 170 µm (Flash tape 5 ®< from the company SOLVAY).Subsequently, a fiberglass mast is positioned against the corner of the thermally insulating barrier before being covered with polyurethane glue. According to an advantageous embodiment, the deposition of the polyurethane glue can be done in two stages. After polymerization of the counter-form 33, the adhesive strip is removed and the counter-form 33 is fixed by one or more additional adhesive waterproof mastic strips similar to the first and / or second adhesive waterproof mastic strip, as in the previous embodiment.

[0123] Furthermore, according to an embodiment illustrated in the figure 13 , the vacuum pump 31 is connected to the enclosed space by means of a connecting device, as illustrated in the figure 13 The connecting device comprises a connecting angle 36 which is advantageously produced by in-situ molding using a process similar to that described above in relation to the counter-form 33. A connecting flange 37 intended to be connected to the vacuum pump 31 is here taken from the mass of the connecting angle 36 during its molding. After polymerization of the connecting angle 36, the connecting angle 36 is pierced opposite the connecting flange 37 in order to allow the enclosed space 19 to be depressurized.

[0124] Subsequently, the connecting angle 36 is fixed in a similar manner to the counter-form 33, i.e. by one or more additional adhesive waterproof mastic strips similar to the first and / or second adhesive waterproof mastic strip.

[0125] As shown in the figure 13 , the connecting angle 36 is advantageously arranged astride two adjacent prefabricated blocks 4 so that the connecting flange 37 is located opposite the space provided between two adjacent prefabricated blocks 4. This facilitates the creation of a vacuum in the enclosed space 19.

[0126] THE figures 5 à 11 illustrate the different stages of installation of a leak testing device according to a second embodiment. In these figures, the elements identical or fulfilling the same function as elements described above with regard to the figures 1 à 4 have the same reference increased by 100. This second embodiment of the sealing device differs mainly in that the polymer film tarpaulin 12 is replaced by metal structures 112 as explained below.

[0127] There figure 5 represents a plurality of adjacent prefabricated blocks 104 whose rigid waterproof films 107 are connected to each other by portions of flexible waterproof film 111. In a manner similar to the first embodiment described above, a first step in the installation of the leak testing device according to the second embodiment consists of applying a layer of polyurethane glue 121 to end portions 116 of the portions of flexible waterproof film 111 intended to receive a first strip of waterproof mastic 117, as illustrated in the figure 6 These layers of polyurethane glue 121 allow good cooperation between the first strip of waterproof mastic 117 and said end portions 116 of the portions of flexible waterproof film 111.

[0128] In a second step of installing the sealing device, as shown in the figure 7 , the first strip of waterproof mastic 117 is applied in a waterproof manner to the peripheral portion 115 of the secondary waterproofing membrane 2. Similarly, the second strip of waterproof mastic 118 is applied in a waterproof manner to the supporting structure 113 around the portion of the tank whose waterproofness of the secondary waterproofing membrane 102 is to be tested.

[0129] In a third step, a counter-form 133 is installed at an angle 134 formed by the secondary thermally insulating barrier 101. This counter-form 33 is for example made of stainless steel.

[0130] The counter-form 133 comprises a first planar wing 135 and a second planar wing 136. The counter-form 133 is installed at the angle 134 so that the first planar wing 135 develops in a plane parallel to the thickness direction of the tank and covers an end portion 137 of a first lateral face 138 of the secondary thermally insulating barrier 101. The counter-form 133 is installed at the angle 134 so that the second planar wing 136 develops in a plane parallel to the thickness direction of the tank and covers an end portion 139 of a second lateral face 140 of the secondary thermally insulating barrier 101, said first end portion 137 and second end portion 139 jointly forming the angle 134 of the secondary thermally insulating barrier 101.

[0131] The counter-form 133 further comprises a third planar wing 141 and a fourth planar wing 142. The third wing 141 extends perpendicular to the first and second planar wings 135, 136 from inner edges of said first and second planar wings 135, 136. Similarly, the fourth planar wing extends perpendicular to the first and second planar wings 135, 136 from outer edges of said first and second planar wings 135, 136. Thus, the third planar wing 141 and the fourth planar wing 142 are parallel and extend in opposite directions and from opposite edges of the first and second planar wings 135, 136. The counter-form 133 is installed at the corner 134 so that the third wing 141 is applied in a sealed manner to the first strip of waterproof sealant 117 and the fourth wing 142 is applied in a sealed manner to the second strip of waterproof mastic 118.Thus, the counter-form 133 is fixed in a sealed manner by means of the strips of waterproof mastic 117 and 118 on the secondary waterproofing membrane 102 and on the supporting structure 113.

[0132] During a fourth stage illustrated on the figure 9 , additional adhesive waterproof sealant strips 143 are applied to the edges of the counter-form 133 which do not cooperate with the first waterproof sealant strip 117 or the second waterproof sealant strip 118.

[0133] During a fifth stage illustrated on the figure 10 , a metal structure 144 is arranged in a sealed manner between the secondary sealing membrane 102 and the supporting structure 113. Such a metal structure 144 comprises a flat central portion 145, a flat internal rim 146 and a flat external rim 147. The inner rim 146 and the outer rim 147 develop perpendicularly to the flat central portion 145. The inner rim 146 and the outer rim 147 develop from opposite edges of the flat central portion 145 and in opposite directions relative to said flat central portion 145. This metal structure 144 is arranged on the tank portion so that the inner rim 146 rests in a sealed manner on the first strip of waterproof mastic 117 and the outer rim 147 rests in a sealed manner on the second strip of waterproof mastic 118, the flat central portion 145 covering the lateral face 138 of the thermally insulating barrier.Furthermore, the metal structure 144 is arranged on the tank portion such that one end of said metal structure cooperates in a sealed manner with one of the complementary waterproof sealant strips 143 arranged on the counter-form 133. Typically, the internal edge 146 of the metal structure 144 cooperates in a sealed manner with the complementary waterproof sealant strip 143 applied to the third wing 141 of the counter-form 133, the flat central portion 145 of the metal structure 144 cooperates in a sealed manner with the complementary waterproof sealant strip applied to the first wing 135 of the counter-form 133 and the external edge 147 of the metal structure 144 cooperates in a sealed manner with the complementary waterproof sealant strip 143 applied to the fourth wing 142 of the counter-form 133. Thus, the metal structure 144 and the counter-form 133 are connected in a sealed manner. by the additional waterproof sealant strip 143.

[0134] Such counter-forms 133 and metal structures 144 are arranged in a similar manner over the entire periphery of the portion of the tank whose sealing of the secondary sealing membrane 102 must be tested in order to form the enclosed space 119 as illustrated in the figure 11 .

[0135] This second embodiment of the leak testing device has good reliability, the counter-forms 133 and the metal structures 144 having good strength and not risking deterioration. In addition, the sealing of the enclosed space 119 is obtained simply and reliably thanks to the strips of waterproof mastic 117, 118 and 143. In addition, this leak testing device is very simple to remove since it is simply necessary to remove the structures 144 and counter-forms 133 then the strips of waterproof mastic 117 and 118, and possibly to sand the layers of polyurethane glue 121.

[0136] In order to ensure good cooperation between, on the one hand, the structures 144 and the counter-forms 133 and, on the other hand, the first strip of waterproof mastic 117 and the second strip of waterproof mastic, it is also possible to apply a force to said structures 144 and counter-forms 133 by means of a clamping device similar to that described above with regard to the figure 4 .

[0137] Furthermore, in order to compensate for the deviations linked to the manufacturing tolerances of the tank portion, it is possible to provide structures 144 and counter-forms 133 in two parts. An internal part of a structure 144 then comprises the internal rim 146 and an internal part of the central portion 145 and an external part of the structure 144 comprises the external rim 147 and an external part of the central portion 145. The step of installing the structure 144 then comprises a first step consisting of installing the lower part or the upper part of the structure, applying a complementary strip of waterproof mastic to the central portion of said part and installing the other part of the structure overlapping so that the lower part and the upper part of the central portion 145 are connected in a sealed manner by a complementary strip of waterproof mastic or by welding.This variant embodiment allows, by playing on the overlap between the internal part and the external part of the central portion 145, to adapt the size of the central portion 145 to compensate for the differences linked to the manufacturing tolerances of the tank.

[0138] Likewise, it is possible to compensate for the flatness defects of the supporting structure 13, 113 by applying several layers of waterproof mastic to form the second strip of waterproof mastic 18, 118. In particular, in the second embodiment of the leak testing device, the flatness defects of the supporting structure 113 can generate a gap that can vary between 4 mm and 30 mm with the metal structures 144 or the counter-forms 133. The application of several superimposed layers of waterproof mastic makes it possible to form the second strip of waterproof mastic 118 with a sufficient thickness to fill these gaps linked to the flatness defects of the supporting structure 113.

[0139] The above description is given for testing the tightness of a secondary waterproofing membrane 2, 102, but the above sealing devices can be installed in a similar manner for testing a primary waterproofing membrane tightness.

[0140] In the context of a leak test of a primary waterproofing membrane, the secondary waterproofing membrane 2, 102 forms a flat and leaktight support surface on which the second strip of waterproof sealant 18, 118 is applied. In one variant, this flat and leaktight support surface is formed by a leaktightness testing device arranged to test the leaktightness of the secondary waterproofing membrane 2, 102. In another variant, the second strip of waterproof sealant 18, 118 is applied to the supporting structure 13, 113 and the secondary waterproofing membrane 2, 102 is also housed in the enclosed space 19, 119. The first strip of waterproof sealant 17, 117 is then applied to the primary waterproofing membrane.

[0141] Furthermore, a clamping device 25 can then be adapted so that the base 28 comprises a clamp, for example of the grasshopper type, which can be clipped onto a portion of primary waterproofing membrane whose waterproofing is to be tested. In the context of a primary waterproofing membrane comprising a first series of parallel undulations and a second series of parallel undulations forming nodes at the intersections between the undulations of the first series of undulations and the undulations of the second series of undulations, the base 28 can then be clipped onto the nodes of said primary waterproofing membrane.

[0142] 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 as defined by the claims.

[0143] 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.

[0144] In the claims, any reference sign in parentheses cannot be interpreted as a limitation of the claim.

Claims

1. A method for testing the seal of a sealing membrane (2, 102), the sealing membrane (2, 102) being fixed to a thermally insulating barrier (1, 101), the thermally insulating barrier (1, 101) resting on a sealed supporting surface (13, 113), the method comprising: - applying a first strip of sealing compound (17, 117) to the sealing membrane (2, 102); - applying a second strip of sealing compound (18, 118) to the supporting surface (13, 113) around the sealing membrane (2, 102), - disposing a sealed cover (12, 144, 133) on the first strip of sealed mastic (17, 117) and on the second strip of sealed mastic (18, 118) so that on the one hand the sealed cover (12, 144, 133) is connected in sealed manner to the sealing membrane (2, 102) by the first strip of sealed mastic (17, 117) and, on the other hand, the sealed cover (12, 144, 133) is connected in sealed manner to the supporting surface (13, 113) by the second strip of sealing compound (18, 118), the sealed cover (12, 144, 133), the supporting surface (13, 113), the first strip of sealing compound (17, 117), the second strip of sealing compound (18, 118) and the sealing membrane (2, 102) together defining an enclosed space (19, 119), the sealed cover being a polymer film tarpaulin (12), - depressurizing the enclosed space (19, 119) with respect to an environment outside said enclosed space (19, 119); and - measuring a parameter representing the variation of the pressure inside the enclosed space (19, 119) after said enclosed space (19, 119) has been depressurized.

2. The seal test method as claimed in claim 1, in which the sealing membrane (2, 102) includes at least one composite sealed film portion (11, 111), the method further including a step of application of an adhesive layer (21, 121) to a face of said at least one composite film portion (111, 11) in such a manner that said adhesive layer (21, 121) is impregnated in the composite film portion (11, 111), the first strip of sealing compound (17, 117) being applied to said face of said at least one composite film portion (11, 111).

3. The seal test method as claimed in claim 2, in which the adhesive layer (21, 121) is a layer of polyurethane glue.

4. The seal test method as claimed in any one of claims 1 to 3, in which the first strip of sealing compound (17, 117) is adhesive and in which the second strip of sealing compound (18, 118) is adhesive.

5. The seal test method as claimed in any one of claims 1 to 4, in which first strip of sealing compound (17, 117) is made of synthetic rubber and in which the second strip of sealing compound (18, 118) is made of synthetic rubber.

6. The seal test method as claimed in any one of claims 1 to 5, in which the polymer film tarpaulin (12) is made of a material chosen from vinyl, nylon and polyethylene.

7. The seal test method as claimed in any one of claims 1 to 6, further including a step of positioning a screen (22, 34) covering an interstice between the thermally insulating barrier (1) and the supporting surface (13) in order to prevent the polymer film tarpaulin (12) from being positioned in said interstice during the depressurization of the enclosed space (19).

8. The seal test method as claimed in any one of claims 1 to 6, further including a step of positioning a protection angle-iron (35) including a first plane flange and a second plane flange so that the first plane flange is disposed against the sealing membrane (2) and the second plane flange extends along an edge of the thermally insulating barrier (1) and projects in the direction of the supporting surface (13).

9. The seal test method as claimed in any one of claims 1 to 8, in which a reinforcing fabric (23) is fixed to the polymer film tarpaulin (12), the tarpaulin being fixed in such a manner that the reinforcing fabric (23) is positioned in the enclosed space (19) at the level of a corner formed by the thermally insulating barrier (1).

10. The seal test method as claimed in any one of claims 1 to 9 further including a step of application of a bearing force in the direction of the supporting surface (13, 113) to the sealed cover (12, 133, 144) in line with the first strip of sealing compound (17, 117) and in line with the second strip of sealing compound (18, 118).

11. The seal test method as claimed in any one of claims 1 to 10, further including a step of fixing a caul sheet (33, 133) at the level of a corner of the thermally insulating barrier (1, 101) so that said caul sheet (33, 133) covers said corner, the caul sheet (33, 133) being connected in sealed manner on the one hand to the supporting surface (13, 113) and, on the other hand, to the sealing membrane (2, 102).

12. The seal test method as claimed in claim 11, in which the caul sheet (33) is made by molding in situ in the corner of the thermally insulating barrier (1).

13. The seal test method as claimed in any one of claims 1 to 12, including a step of positioning a connecting device including a connecting angle-iron (36) and a connecting flange (37) disposed facing an orifice formed in said connecting angle-iron (36), said connecting angle-iron (36) being connected in sealed manner to the supporting surface (13), to the sealing membrane (2) and to the sealed cover (2) and the connecting flange (36) being connected in sealed manner to a means (31) for depressurizing the enclosed space (19).

14. The seal test method as claimed in claim 13, in which the connecting angle-iron (36) is made by molding it in situ on the thermally insulating barrier (1), the connecting flange (37) being embedded in the mass of the connecting angle-iron (36) during molding thereof.

15. A sealing device for closing an enclosed space (19, 119) defined between a sealing membrane (2, 102) fixed to a thermally insulating barrier (1, 101) anchored to a supporting surface (13, 113) and said supporting surface (13, 113); the sealing device including - a sealed cover (12, 133, 144) connected in sealed manner too, on the one hand, the sealing membrane (2, 102) by means of a first strip of sealing compound (17, 117) and, on the other hand, to the supporting surface (13, 113) by means of a second strip of sealing compound (18, 118), the sealed cover being a polymer film tarpaulin (12), and - a vacuum pump connected to the enclosed space (19, 119) and able to depressurize said enclosed space (19, 119).

16. The sealing device as claimed in claim 15, in which the sealed cover includes a polymer film tarpaulin (12), the sealing device further including a screen (22) covering an interstice between the thermally insulating barrier (1) and the supporting surface (13) in such a manner as to block said interstice and to prevent the insertion of the polymer film tarpaulin (12) in said interstice in the presence of depressurization of the enclosed space (19).

17. The sealing device as claimed in claim 15 or 16, further including a clamping device (25) adapted to exert a bearing force in the direction of the supporting surface (13, 113) on the sealed cover (12, 133, 144) in line with the first and second strips of sealing compound.