RU2780761C2 - Leakage detection device for sealing membrane - Google Patents

Abstract

FIELD: sealing.

SUBSTANCE: group of inventions relates to leakage detection means in sealing membrane (5, 8) of a tank. Bell-shaped leakage detection device (55) contains main case (100) intended for placement in testing zone (62). Seal (60) is connected to main case (100), made with the possibility of limitation of detection chamber (61) between main case (100) and testing zone (62). At the same time, seal (60) contains peripheral sealing edge (64) having a closed contour for embracing testing zone (62). Bell-shaped leakage detection device (55) also contains a mechanical pressing means supported by main case (100), made with the possibility of exertion of pressure directed to membrane (5, 8) on seal (60).

EFFECT: reliability and ease of use.

20 cl, 17 dwg

Description

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES

[0001] The invention relates to a bell-shaped leak detection device for detecting leaks in a sealing membrane, in particular in a corrugated sealing membrane, for example, in a sealed tank. These sealed containers may be, for example, sealed and insulated tanks for storing and/or transporting a fluid, such as a cryogenic fluid.

BACKGROUND OF THE INVENTION

[0002] Document KR 1020100050128 discloses a method for testing the sealing of the membrane of a sealed and thermally insulated LNG storage tank.

The tank contains a multilayer structure and sequentially has, from the outer side to the inner side, an auxiliary insulating space, an auxiliary sealing membrane, a main insulating space and a main sealing membrane designed to contact with liquefied natural gas contained in the tank. More specifically, the method is designed to detect leaks through weld beads that allow the metal sheets of the main sealing membrane to seal together. The method involves injecting a tracer gas into the main insulating space, and then moving the detection equipment, equipped with a tracer gas analyzer, inside the tank along the welded beads of the main sealing membrane. Thus, if the detection equipment detects the presence of a tracer gas, it can be concluded that there is a seal failure in the main seal membrane. In such a method, the injection of tracer gas into the main containment space is critical, since the detection method can only provide reliable results if the tracer gas has been uniformly distributed throughout the main containment space.

[0003] In addition, the detection equipment is formed from a tracer gas suction unit and a tracer gas detector. The suction unit is moved along the entire length of the weld bead using a carriage, with the carriage located on the bottom wall of the tank and the suction unit attached to the carriage so as to be located on the weld bead of the wall adjacent to the bottom wall. However, using this equipment, it is difficult to check all the weld beads of the tank, because the equipment is bulky and must be connected to the carriage on the bottom wall. This equipment is also very slow because the equipment only checks a small section of the weld bead at a time, and the equipment assembly on the carriage must be changed to change the weld bead.

SUMMARY OF THE INVENTION

[0004] One idea behind the invention is to provide a bell-shaped detection device or a leak detection device for testing a tank seal membrane seal that is reliable and easy to use in a tank.

[0005] Another idea behind the invention is to provide a bell-shaped detection device or a leak detection device that can be quickly used to test a tank seal membrane seal in a minimum amount of time.

[0006] Another idea underlying the invention is to provide a membrane seal test method that is reliable and fast to implement.

[0007] According to one embodiment, the invention provides a bell-shaped leak detection device for detecting a leak in a tank seal membrane test area, the bell-shaped detection device comprising:

- the main body, designed to be placed in the test area;

a seal connected to the main body and configured to define a detection chamber between the main body and the test area, the seal comprising a peripheral sealing lip having a closed loop to enclose the test area;

- mechanical pressing means supported by the main body and containing at least one pressing element configured to apply pressure to the sealing lip portion directed towards the membrane when the main body is located in the test area.

[0008] Due to these features, the bell-shaped detection device can be quickly placed in the test area, so that the seal can form a detection chamber throughout the test area. In addition, the mechanical pressing means makes it possible to press the sealing lip against one or more areas, especially where there is a risk of the seal disengaging from the sealing membrane, in order to increase the reliability of the bell-shaped detection device in detecting a possible leak.

[0009] Preferably, the bell-shaped detection device is capable of detecting a tracer gas. According to one possibility offered by the invention, this tracer gas is not necessarily injected into the zone where the compaction is examined, it can be introduced into the zone in another way.

[0010] In addition, thanks to the bell-shaped leak detection device according to the invention, a vacuum of less than 100 Pa in the detection chamber, for example, of the order of 50 to 60 Pa (0.5-0.6 mbar) can now be easily achieved.

[0011] According to other preferred embodiments, such a bell-shaped device may have one or more of the following features.

[0012] According to one embodiment, the pressure member is an elastically deformable member that exerts pressure on a portion of the sealing lip by elastic deformation.

[0013] Thus, the elasticity of the pressing element allows, during its elastic deformation, to induce a response force on the sealing lip in the direction of the sealing membrane.

[0014] According to one embodiment, the pressure member is oriented perpendicular to the contour of the peripheral sealing lip.

[0015] According to one embodiment, the sealing lip is in an operational state when vacuum is applied to the detection chamber, wherein a portion of the sealing lip is held between the main body and the sealing membrane over at least a portion of the periphery of the detection chamber, preferably over the entire periphery of said chamber.

[0016] According to one embodiment, the bell-shaped leak detection device has an elongated shape, the length of which is greater than or equal to 0.5 m, preferably greater than or equal to 1 m, more preferably greater than or equal to 2 m.

[0017] According to one embodiment, the mechanical pressing means comprises a plurality of pressing elements configured to exert pressure on a plurality of sealing lip portions, the portions being located at the two ends of the sealing lip in the longitudinal direction.

[0018] According to one embodiment of the invention, the portions of the sealing lip pressed by the mechanical pressing means are located at the two ends of the sealing lip in the longitudinal direction, that is, at the two ends of the bell-shaped device, given that said device has a generally longitudinal shape.

[0019] Thus, the mechanical pressing means applies pressure to various areas where there is a risk of seal detachment, namely the ends of the seal.

[0020] According to one embodiment, the sealing lip comprises at least one cavity shaped to match the shape of the corrugation of the membrane, the cavity being designed to enclose the corrugation.

[0021] According to one embodiment, the sealing lip comprises at least two pits, such as three pits.

[0022] Due to these features, it is possible to place a bell-shaped detection device on a sealing membrane containing corrugated sheets, with one or more depressions allowing the bell-shaped device to surround the corrugations.

[0023] According to one embodiment, the portion of the sealing lip pressed by the mechanical pressing means is located at the base of the cavity.

[0024] Due to this feature, the bell-shaped detection device can be placed on the sealing membrane containing corrugated sheets, and one or more depressions allow the bell-shaped device to cover the corrugations.

[0025] Thus, the mechanical pressing means applies pressure to the area where there is a risk of the seal coming off due to the change in the inclination of the cavity.

[0026] According to one embodiment, the mechanical pressing means comprises a plurality of pressing elements configured to exert pressure on a plurality of sealing lip portions, the portions being located at the bases of the trough or troughs.

[0027] Thus, the mechanical pressing means applies pressure to various areas where there is a risk of the seal coming loose, namely the base of one or more depressions.

[0028] According to one embodiment, the sealing lip portion is located at the top of the valley.

[0029] According to one embodiment of the invention, all areas of the sealing lip located at the bases of the cavity are pressed by a plurality of pressure elements of the mechanical means.

[0030] According to one embodiment, at least one, part or pressing elements comprise a curved strip, at least one of the ends of which abuts against the base of the cavity.

[0031] Preferably, at least one, part or pressing elements contain a curved strip, the two ends of which abut against the base of two adjacent depressions.

[0032] Due to this feature, it is easier to position the leak detection bell because the curved band will allow the pressure of the sealing lip troughs to be correctly distributed to the two adjacent membrane ridges, regardless of any slight changes in the distance between these two adjacent ridges or the approximate location of the leak detection bell on ribbed membrane by one or more operators.

[0033] According to one embodiment, the mechanical pressing means comprises a carrier element extending along the entire length of the main body, above and attached to said main body.

[0034] According to one embodiment, the curved strips are distributed along the sealing lip and are attached to the support element by attachment means.

[0035] According to one embodiment, the curved strips are elastically deformable so that upon deformation, an elastic response force is applied to the sealing lip.

[0036] According to one embodiment, the attachment means comprise a plurality of pins, each pin comprising a rod freely mounted on the housing, the rod having an end abutting against one of the curved strips; the housing is attached to the carrier and also contains a spring connecting the rod to the housing, the spring acting between the housing and the rod to place the end of the rod against the curved strip, the spring being configured to cause a response force to act on the curved strip so that the curved strip pressed the sealing lip against the base of the corrugation.

[0037] According to one embodiment, the mechanical pressing means comprises a plurality of end pressing elements, the end pressing elements being located at the two ends of the sealing lip in the longitudinal direction, that is, at the two ends of the bell-shaped device, given that said device has a longitudinal shape.

[0038] Thus, the length of the bell device according to the invention may be at least one (1) meter and a width of 10 to 20 centimeters (cm), preferably 14 cm to 16 cm.

[0039] The bell-shaped leak detection device according to the present invention is capable, when used in a membrane zone containing ridges, to test a plurality of ridges (one or more weld points present on said ridge or on said ridges), that is, at least three (3) comb and up to almost ten combs. It is also possible to consider connecting a plurality of detection bells one next to the other or one behind the other to form a larger/substantial length of the test zone, where only one vacuum pump can then be used to create the required vacuum in these leak detection bells that are connected together.

[0040] Such a bell-shaped detection device can weigh from 3 kg to 25 kg, preferably from 5 kg to 10 kg, in particular, depending on the materials used, its length and width.

[0041] According to one embodiment, at least one or end pressure members comprise an end pin, the end pin comprising a shaft loosely mounted on the body; an elongated support element is attached to the end of the rod, while the elongated support element abuts against the sealing edge, and the body is attached to the carrier element, the end pin also contains a spring connecting the rod to the body, while the spring acts between the body and the rod in order to position the elongated the support element against the sealing lip, wherein the spring is configured to cause a response force to the elongated support element so that the elongated support element presses the sealing lip against the area to be examined.

[0042] According to one embodiment, the second end is provided with an elongate abutment, the elongate abutment being configured to transmit an elastic response force to a sealing lip area corresponding to the length of the elongated abutment.

[0043] According to one embodiment, the second end of the first end pin and the second end of the second end pin adjacent the first end pin are attached together by an elongated support member.

[0044] According to one embodiment, at least one or end pressure members comprise a plurality of adjusting members forming a series of members, the adjusting member comprising a stem extending towards the sealing lip and an adjustable end in the longitudinal direction of the stem to contact the sealing lip after adjustment.

[0045] According to one embodiment, the pressure element comprises a curved strip containing, at one of its ends, which is in contact with the sealing edge, a cylindrical sleeve.

[0046] Thus, the cylindrical sleeve allows the pressure of the mechanical pressing means to be uniformly applied to the sealing lip portion.

[0047] According to one embodiment, the seal comprises a casing which at least partially covers the main body and which is attached to the main body, wherein the peripheral sealing lip is connected to the casing so as to extend said casing and is curved opposite to the main body.

[0048] According to one embodiment, the cylindrical sleeve comprises a longitudinal direction, wherein the longitudinal direction of the cylindrical sleeve is substantially perpendicular to the casing, such that the cylindrical sleeve protrudes from the casing at one end of the sealing lip.

[0049] According to one embodiment, the sealing lip comprises a curved portion substantially perpendicular to the casing, the curved portion having a cross-sectional dimension greater than or equal to 1 cm, preferably greater than or equal to 1.5 cm, more preferably greater than or equal to 2 cm.

[0050] In one embodiment, the seal is made from an elastomeric material having a hardness of 20 to 50 Shore A.

[0051] Due to these features, the seal is made of a material that is flexible enough to be deformed by mechanical pressing means.

[0052] In one embodiment, the elastomeric seal material is selected from a polyurethane elastomer and ethylene propylene diene monomer (EPDM) rubber. The elastomeric seal material can also be made from silicone, nitrile or Viton®.

[0053] According to one embodiment, the main body comprises a rigid center portion, and the seal comprises a casing sealed against a peripheral wall of the rigid center portion.

[0054] According to one embodiment, the rigid center portion includes a recess on the bottom surface that is designed to pivot towards the test area.

[0055] According to one embodiment, the rigid center includes a channel connecting the recess to the top surface of the rigid center for attaching a vacuum pump.

[0056] According to one embodiment, the invention provides a leak detection device for testing the seal of a sealed and thermally insulated tank, the leak detection device comprising:

- a bell-shaped leak detection device, as described above;

- a vacuum pump connected to the detection chamber;

- analysis apparatus connected to the detection chamber to analyze the amount of gas present in the detection chamber.

[0057] According to one embodiment, the invention provides a leak detection assembly in a tank seal membrane test area, the assembly comprising:

- a bell-shaped leak detection device, as described above, or a leak detection device, as described above;

- a sealing membrane containing the test area;

moreover, the bell-shaped leak detection device is located on the test area so that the sealing lip surrounds the test area.

[0058] According to one embodiment, the invention provides a method for operating a leak detection device as described above in a tank seal membrane test area, the method comprising the steps of:

— place the bell-shaped detection device on the test area so that the sealing lip completely encloses the test area;

applying pressure to the sealing lip with mechanical pressure means to press the sealing lip against the sealing membrane;

- relieve pressure in the detection chamber by means of a vacuum pump;

supplying the gases present in the detection chamber to the analysis apparatus; and

- analyze by means of the apparatus for analysis gases emanating from the detection chamber, and provide a variable representing the gases present in the detection chamber.

[0059] According to one embodiment, the leak detection bell is oriented in the test area such that the length of the leak detection bell overlaps with the test area.

[0060] According to one embodiment, the test zone is part of the sealing membrane seal bead.

[0061] Thus, a bell-shaped leak detection device is used to confirm that there is no damage to the sealing bead that may cause leakage in the sealing membrane.

[0062] According to one embodiment, the test area is located on a corrugated sealing membrane.

[0063] According to one embodiment, the invention provides a method for testing the sealing of a membrane of a sealed and heat-insulating tank, wherein the sealed and heat-insulating tank has a polygonal shape bounded by a plurality of tank walls that are fixed to a supporting structure, each of the tank walls containing a heat-insulating barrier containing insulating elements fixed on the supporting structure, while the membrane rests on the insulating elements of the heat-insulating barrier; the heat-insulating barriers of the walls of the tank are connected together and together define the heat-insulating space; moreover, the method of testing the seal contains the following steps, in which:

- inject indicator gas into the heat-insulating space;

- delivering a leak detection device containing a bell-shaped detection device configured to limit a sealed detection chamber with a membrane, and a vacuum pump, which, on the one hand, is connected to the detection chamber, and on the other hand, to the analysis equipment;

- positioning the bell-shaped detection device at the surface of the membrane opposite the heat-insulating space, wherein the bell-shaped detection device is positioned so that the detection chamber is positioned facing the area of the weld bead to be examined;

-- relieve pressure in the detection chamber using a vacuum pump;

- serving the gas phase contained in the detection chamber to the apparatus for analysis; and

- analyzing by means of the apparatus for analysis said gas phase and providing a variable representing the concentration of indicator gas in said gas phase.

[0064] It is understood that the pressure applied to the sealing lip before depressurizing the detection chamber acts on the surface of said lip outside the detection chamber. Thus, the sealing lip, which may be a single element, defines a sealed or sealed volume intended to become, after depressurization, a depressurization chamber.

[0065] According to one embodiment, the invention provides a leak detection device for testing the seal of a membrane of a sealed and thermally insulated tank; moreover, the leak detection device comprises a bell-shaped detection device configured to delimit a sealed detection chamber with a membrane, and a vacuum pump, which, on the one hand, is connected to the detection chamber, and, on the other hand, to the analysis apparatus.

[0066] According to embodiments, the method for testing a membrane seal and/or a leak detection device may comprise one or more of the following features.

[0067] According to one embodiment, tracer gas is injected into the thermal insulation space by said tracer gas injection method. However, according to another embodiment, the tracer gas can also be injected into the heat-insulating space using a different method.

[0068] According to one embodiment, the analysis apparatus is a mass spectrometer.

[0069] According to one embodiment, the bell-shaped detection device has an elongated shape.

[0070] In one embodiment, the bell-shaped detection device comprises a rigid core and a seal that are bonded to each other and positioned to delimit a membrane detection chamber to be examined.

[0071] According to one embodiment, the seal comprises a casing attached to a rigid central portion and a peripheral sealing lip that extends the casing.

[0072] According to one embodiment, the seal housing has a base that covers the upper surface of the rigid center and a peripheral wall that corresponds to the periphery of the rigid center.

[0073] According to one embodiment, the peripheral sealing lip is curved outward of the detection bell and is configured to bend and press against the membrane when the detection chamber is depressurized.

[0074] According to one embodiment, the weld bead portion is traversed by at least one corrugation of the membrane.

[0075] According to one embodiment, the peripheral sealing lip is shaped to adapt to the geometry of said at least one corrugation.

[0076] According to one embodiment, the sealing bead portion is traversed by at least two parallel corrugations, eg three corrugations, of the membrane, the peripheral sealing lip being shaped to adapt to the geometry of said corrugations.

[0077] According to one embodiment, the peripheral sealing lip comprises at least two pits shaped to match the shape of the corrugation of the membrane protruding into the reservoir, said pits being designed to enclose said corrugation.

[0078] In one embodiment, at least one corrugation of the membrane protrudes toward the inside of the reservoir, with a bell-shaped detection device positioned on the membrane so that the depressions surround the corrugation.

[0079] According to one embodiment, the peripheral sealing lip comprises at least two protruding zones, the shape of which corresponds to the shape of the corrugation of the membrane protruding towards the outside of the reservoir.

[0080] According to one embodiment, the bell-shaped detection device is located on the membrane so that the protruding zones are inserted into the corrugation.

[0081] In one embodiment, the seal is made of an elastomeric material having a hardness of 20 to 50 Shore A.

[0082] In one embodiment, the elastomeric seal material is selected from polyurethane elastomer, silicone, nitrile, and Viton®.

[0083] According to one embodiment, the bell-shaped detection device is equipped with a clamping system capable of pressing the peripheral sealing lip against the membrane to be tested.

[0084] According to one embodiment, prior to depressurizing the detection chamber, the clamping system is activated so as to seal the detection chamber.

[0085] According to one embodiment, when the seal comprises at least two cavities with a shape that matches the shape of the corrugation of the membrane protruding to the outside of the tank and passing through the section of the welded bead, the clamping system includes a clamp on each of the cavities, each the clamp comprises two branches respectively located on each side of the cavity and configured to apply a clamping force from the peripheral sealing edge to the corrugation of the membrane.

[0086] According to one embodiment, the detection chamber is depressurized to an absolute pressure value in the range of 10 Pa to 1000 Pa, preferably below 100 Pa absolute.

[0087] According to one embodiment, the gas phase is analyzed for a time that is greater than or equal to 5 seconds.

[0088] According to one embodiment, a variable representing the indicator gas concentration in said gas phase is compared to a threshold value, and sealing of the weld bead portion is considered defective when the variable representing the tracer gas concentration in said gas phase is above said threshold.

[0089] According to one embodiment, the leak detection device further comprises a homogenization chamber, which is located between the detection chamber and the analysis apparatus, and the bell-shaped detection device includes a gas supply channel equipped with a cock, and the homogenization chamber and the gas supply channel are connected at two opposite ends of the chamber detection.

[0090] According to one embodiment, the valve of the gas supply channel is closed when the detection chamber is depressurized, and the step of supplying the gas phase contained in the detection chamber comprises the steps of:

- open the tap of the gas supply channel and supply the gas phase contained in the detection chamber to the homogenization chamber; and

- the gas phase is fed from the homogenization chamber to the apparatus for analysis.

[0091] According to one embodiment, the invention provides a method for controlling the diffusion of a tracer gas in a thermally insulating space.

[0092] According to one embodiment, the indicator gas diffusion control method is implemented during the above seal test method. However, in another embodiment, it can also be implemented independently.

[0093] According to one embodiment, controlling the diffusion of tracer gas in the heat-insulating space comprises the steps of:

- take a sample of the gas contained in the heat-insulating space, by means of a plurality of samplers, each of which passes through the membrane of one of the walls of the tank; and

- submit the selected gas to the apparatus for analysis, such as a mass spectrometer, for example.

[0094] According to one embodiment, the samplers are preferably located near the corner zones formed at the junction between two or three walls of the tank.

[0095] According to one embodiment, each gas sampler comprises a cover plate that is connected to the membrane by a mastic bead enclosing a non-welded area of the membrane at a junction between two membrane elements, the cover plate having an opening and a connector for connection to a pipe, connected to the analysis apparatus, said connector being hermetically welded on the periphery of the opening of the cover plate.

[0096] According to one embodiment, the gas sampler comprises a connecting component that has an end connection designed to seal with a channel connected to the analysis apparatus, a shoulder, and a lower threaded rod that protrudes from the shoulder, passes through the auxiliary membrane and is screwed into a threaded hole made in a plate attached to the thermal barrier; moreover, the gas sampler additionally contains an annular seal, which is threaded on the lower rod and which is placed in the middle between the auxiliary membrane and the shoulder, while the connecting component has a perforation that goes from one side to the end connection, and from the other side - into the heat-insulating space.

BRIEF DESCRIPTION OF THE DRAWINGS

[0097] The invention will be better understood and its additional objects, details, features and advantages will become clearer and more apparent throughout the following description of a variety of particular embodiments of the invention, which are presented solely by way of non-limiting illustration, with reference to the accompanying drawings, in which:

[0098] FIG. 1 is a schematic view of a leak detection device according to the first embodiment.

[0099] FIG. 2 is a cross-sectional view along plane II-II of the bell-shaped detection device of the leak detection device in FIG. one.

[0100] FIG. 3 is a perspective view of a seal according to the first embodiment;

[0101] FIG. 4 is a schematic view of an alternative embodiment of a leak detection device in which the bell-shaped detection device is equipped with a clamping system.

[0102] FIG. 5 is a perspective view of a seal according to the second embodiment.

[0103] FIG. 6 schematically illustrates the position of the bell-shaped detection device facing the area of the welded bead providing a seal between two adjacent corrugated metal sheets of the membrane.

[0104] FIG. 7 is a schematic view of a leak detection device according to the second embodiment.

[0105] FIG. 8 is a perspective view of the bell-shaped leak detection device according to the third embodiment.

[0106] FIG. 9 is a schematic cross-sectional view of the bell-shaped detection device of FIG. 8, before depressurizing the detection chamber.

[0107] FIG. 10 is a schematic cross-sectional view of the bell-shaped detection device of FIG. 8, after depressurizing the detection chamber.

[0108] FIG. 11 is a schematic illustration of a sandwich construction of a membrane tank wall.

[0109] FIG. 12 is a partial schematic view of a sealed and insulated tank illustrating a tracer gas injection device located through the bottom wall membrane of the tank.

[0110] FIG. 13 is a perspective view of a bell-shaped leak detection device according to the fourth embodiment.

[0111] FIG. 14 is an exploded view of detail XIV in FIG. 13 illustrating the pressure member of the bell-shaped leak detection device.

[0112] FIG. 15 shows an exploded view of detail XV in FIG. 13 illustrating the first end of the bell-shaped leak detection device.

[0097] FIG. 16 is an exploded view of detail XVI in FIG. 13 illustrating the second end of the bell-shaped leak detection device.

[0114] FIG. 17 shows an exploded view of detail XVI in FIG. 13 from a different viewing angle.

DESCRIPTION OF EMBODIMENTS

[0115] A leak detection device that can be used to detect leaks in various sealed assemblies, such as welded assemblies, will be described here. In the following examples, the weld assembly is a seal membrane for a fluid reservoir.

[0116] During the step in which the seal is tested to check the seal of the seal beads of the membrane 5, 8, a leak detection device 54 is used as shown in FIG. one.

[0117] The leak detection device 54 includes a bell-shaped detection device 55 that is designed to be placed against the inner surface of the membrane 5, 8 facing the portion of the weld bead to be tested.

[0118] The bell-shaped detection device 55 has an elongated shape and a length of 0.5 m to 4 m, for example, about 1 m. The length of the bell-shaped detection device 55 is preferably as long as possible in order to check the sealing of a larger area during the time of the same test. However, the choice of this length of the bell device can be adapted depending on, on the one hand, the dimensions of the membrane 5, 8, and thus the reservoir to be examined, and, on the other hand, depending on its maneuverability for a minimum number of operator(s) .

[0119] As shown in FIG. 2, the bell-shaped detection device 55 comprises a rigid main body 100 and a flexible seal 60 which are bonded together and which are positioned to define a sealed detection chamber 61 with the membrane 5, 8 to be examined, the chamber being positioned facing the portion of the weld bead 62 to be examined. research.

[0120] With additional reference to FIG. 1, it can be seen that the leak detection device 54 also includes an analysis apparatus 56 which is connected to the detection chamber 61 and allows tracer gas to be detected. Once the analysis apparatus 56 detects an amount of tracer gas that is above a threshold, it can be concluded that there is seal failure in the region of the weld bead 62 being examined. In one embodiment, the analysis apparatus 56 is a mass spectrometer.

[0121] The leak detection device 54 also includes a vacuum pump 57 that is connected to said analysis apparatus 56. The vacuum pump 57 is connected, on the one hand, to the detection chamber of the bell-shaped detection device 55, so as to allow depressurization in the detection chamber, and, on the other hand, to the analysis apparatus 56, so as to supply the gas contained in the detection chamber 61 , to apparatus 56 for analysis.

[0122] The vacuum pump 57 is connected to the detection bell 55 through a pipe 58, which is preferably flexible. The pipe 58 is connected to a channel which is provided in the main body 100 and opens into the detection chamber 61 .

[0123] As shown in Figures 2 and 3, the main body 100 includes a rigid center portion 59, and the seal 60 includes a casing 63 corresponding to the shape of the rigid center portion 59 and a peripheral sealing lip 64 that extends the casing 63 down. The casing has a bottom 63 which covers the top surface of the rigid center portion 59 and a peripheral wall 74 which corresponds to the periphery of the rigid center portion 59. The bottom 63 has at least one opening, not shown, which is connected to seal a pipe with a vacuum pump 57. The rigid core 59 includes a recess 79 on its bottom surface 80 along the entire length of the rigid core 59. The recess 79 allows, during depressurization of the detection chamber 61, despite the fact that the rigid core 59 is lowered towards the membrane 5, 8, due to the deformation of the sealing lip 64, the test zone 62 is always in fluid contact with the detection chamber 62. In addition, the rigid center portion 59 also includes a channel 82, not shown in FIG. 2, because it only represents a plane passing near the tube 58, allowing the recess 79 to connect with the upper surface 81 of the rigid center 59. The channel 82 allows the detection chamber 61 to connect to the vacuum pump 57 and the analysis apparatus 56 through the tube 58.

[0124] The peripheral sealing lip 64 is curved outward of the bell-shaped detection device 55 and is thus configured to flex and press against the membrane 5, 8 when the sealed chamber 61 is depressurized. In other words, the peripheral sealing lip 64 has a cross section that is generally L-shaped.

[0125] The width of the outwardly curved portion of the peripheral sealing lip 64 is on the order of 15 mm to 40 mm. The peripheral sealing lip 64 is shaped to adapt to the geometry of the membrane 5, 8 along the weld bead to be tested. In addition, in FIG. 3, the peripheral sealing lip 64 comprises depressions 65 shaped to match the corrugations of the membrane 5, 8, which the bell-shaped detection device 55 is intended to enclose when in position against the portion of the weld bead 62 to be tested.

[0126] Seal 60 is preferably made of an elastomeric material having a hardness of 20 to 50 Shore A. For example, the seal is made of polyurethane elastomer, EPDM rubber, silicone, nitrile, or Viton®.

[0127] In one embodiment, schematically illustrated in FIG. 4, the detection bell 55 is also equipped with a mechanical pressing means 66, which in this embodiment is a clamping system 66 capable of pressing the peripheral sealing lip 64 against the membrane 8 to be tested so as to seal the detection chamber 61. The clamping system 66 in this case comprises a clamp 67 on each of the indentations 65 of the peripheral sealing lip 64. Each clamp 67 comprises two branches respectively located on either side of the recess 65 and configured to apply a clamping force from the peripheral sealing lip 64 to the membrane 8. Preferably , the branches are configured to clamp the peripheral sealing lip 64 against the sealing membrane, near the base of the corrugation.

[0128] In addition, in the embodiment shown, the clamping system 66 further comprises, at each of the longitudinal ends of the bell-shaped detection device 55, a movable pin 68 that is configured to press one of the longitudinal ends of the peripheral sealing lip 64 against the membrane 8.

[0129] FIG. 5 illustrates a seal 60 according to an alternative embodiment. This seal 60 is shaped to adapt to the membrane 5 in which the corrugations protrude towards the outside of the tank. Such a membrane is, for example, an auxiliary membrane 5 using Mark V technology. In addition, the peripheral sealing lip 64 includes protruding zones 69 intended to be inserted inside the corrugations of the membrane 5.

[0130] The procedure for detecting damage to the weld bead seal is as follows.

[0131] First, the detection bell 55 is positioned facing the portion of the weld bead 62 to be tested, as shown in FIG. 6.

[0132] The detection bell 55 must be checked to ensure that it is correctly centered relative to the weld bead 62 such that the two lateral parts of the curved portion of the peripheral sealing lip 64 are located on either side of the weld bead 62.

[0133] The vacuum pump 57 is then run to depressurize the detection chamber 61 and facilitate tracer gas migration through damaged areas of the weld bead 62.

[0134] Once the pressure inside the detection chamber 61 falls below the pressure threshold Ps, the gas stream is transported from the detection chamber 61 to the analysis apparatus 56, and the tracer gas leakage rate φ is measured for a minimum duration Tm. The leakage rate ϕ is then compared with a threshold value ϕs.

[0135] If the leakage rate ϕ is less than the threshold value ϕs, then it is concluded that the test portion of the weld bead 62 has no seal damage. In this case, the bell-shaped detection device 55 is then positioned facing the adjacent section of the weld bead 62 by forming a coating between the two successively examined sections, so as to ensure that the seal of the weld bead 62 has been examined along the entire length of said weld bead 62.

[0136] In the opposite case, if the leakage rate ϕ is greater than or equal to the threshold value ϕs, then it is concluded that the investigated area of the weld bead 62 has seal damage. Corrective welding measures are then implemented to repair the damage.

[0137] As an example, for a helium concentration in the insulating space of about 20%, the pressure threshold below which the leakage rate is measured is 10 Pa to 1000 Pa absolute, preferably less than 100 Pa absolute. As an example, the minimum leakage rate measurement duration is 5 seconds and the threshold value ϕs is in the order of 1.0⋅10 ^-6 Pa.m ³ .s ^-1 .

[0138] FIG. 7 shows a leak detection device 54 according to another embodiment. This embodiment differs from the previously described embodiment in that it further comprises a homogenization chamber 70 which is located between the detection chamber 61 and the analysis apparatus 56, and in that the detection bell 55 includes a gas supply passage 71.

[0139] The gas supply channel 71 is provided with a cock for generating or interrupting the flow of ambient air towards the chamber 61. The homogenization chamber 70 is attached at one end of the detection chamber 61, while the gas supply channel 71 is connected at the opposite end of the detection chamber 61.

[0140] The operating mode of the leak detection device 54 is as follows.

[0141] When the detection bell 55 is positioned facing the portion of the weld bead 62 to be tested, the valve of the gas supply passage 71 is closed and the vacuum pump 57 is started to depressurize the detection chamber 61. As soon as the pressure inside the detection chamber 61 falls below the threshold pressure value Ps, the valve of the gas supply channel 71 is opened, and all gases previously contained in the sealed chamber are transferred to the homogenization chamber 70. The volume of the homogenization chamber 70 is larger than the volume of the detection chamber 61 and includes, for example, a piston system for precisely sucking all the gases contained in the detection chamber 61 .

[0142] The gas contained in the homogenization chamber 70 is sequentially supplied to the analysis apparatus 56 in order to determine the tracer gas leakage rate ϕ.

[0143] Such an embodiment is preferred in that it allows the diffusion time of the tracer gas within the detection bell 55 to be reduced and thus allows the minimum measurement duration to be reduced. This is particularly advantageous when the time required for the tracer gas to migrate from one end to the other of the detection bell 55 is likely to be long due to the significant length of the detection bell 55 and/or when the vacuum prevailing inside the detection chamber 61 is insufficient.

[0144] FIG. 8 shows a bell-shaped detection device 55 according to the third embodiment. The bell-shaped detection device 55 in FIG. 8 is constructed similarly to the bell-shaped detection device 55 in FIG. 4, but is especially different with respect to the mechanical pressing means 66. Indeed, the bell-shaped detection device 55 comprises a main body 100 extending in the longitudinal direction, a flexible seal 60 attached to the main body 100, and a mechanical pressing means 66 supported by the main body and configured with the ability to exert pressure directed towards the membrane 5, 8 on the seal 60. The main body 100 includes a rigid center portion 59. The rigid center portion 59 includes a channel 82 allowing the bottom surface 80 to connect with the upper surface 81 of the rigid center portion 59. The channel 82 allows the chamber 61 detection connect to the outlet 78 of the gas.

[0145] The seal 60 includes a casing 63 attached to the rigid center portion 59 by a fastening means 110, for example, including a hoop surrounding the entire circumference of the rigid center portion 59 and the seal 60, and fastening the two elements 59/60 together by means of a mechanical fastening element. such as screws. The seal 60 also includes a peripheral sealing lip 64 connected to the casing 63 and having a closed contour to enclose the portion of the weld bead 62 to be tested. The peripheral edge 64 is also bent in the opposite direction to the main body 100 so as to have a portion of the peripheral edge 64 substantially parallel to the membrane 5,8. membranes 5, 8 to be tested. Thus, when the bell-shaped detection device 55 is placed on the membrane 5, 8, the depressions 55 allow the bell-shaped detection device 55 to adapt to the corrugated shape of the membrane 5, 8. be discharged when the detection chamber 61 is depressurized.

[0146] The mechanical pressing means comprises a carrier 73 extending along the entire length of the main body 100 above and attached to said main body 100. Handles 76 are attached to the two longitudinal ends of the carrier 73 so as to allow the detection bell 55 to be operated by an operator and possibly to allow the mechanical pressing means to be activated by the force of the operator.

[0147] The mechanical pressing means 66 is formed from a plurality of pressing elements 72 which are in the form of curved strips 72 distributed along the sealing lip 64 and which are attached to the bearing member 73 by fastening means 77 . The curved strips 72 are designed to be elastically deformable so that, when they are deformed, to cause an elastic response force to be applied to the sealing lip 64 in order to press them against the membrane 5, 8. press the sealing lip 64 in areas where the risk of detachment is greatest. For this reason, the curved strips 72 are in particular located at the bases of the depressions 64 of the sealing lip 64 and at the longitudinal ends of the bell-shaped detection device 55 on the sealing lip 64.

[0148] A plurality of curved strips 72 are attached, at one of their ends, to the carrier 73, while the other end is placed on the sealing lip 64. These strips 72, in particular, are placed at the ends of the bell-shaped detection device 55. The other curved strips 72 are, for their part, fixed at their centers to the carrier 73, while their two ends are placed on the sealing lip 64, so as to apply pressure on two different zones, these strips 72 in particular being placed between two depressions. 65.

[0149] The curved strips 72 have a cylindrical sleeve 75 at each of their ends in contact with the sealing lip 64. The cylindrical sleeve 75 in particular allows uniform pressure to be applied to the sealing lip 64 while avoiding any punching that could compromise the integrity of the sealing lip 64 The cylindrical sleeve 75 extends in a direction perpendicular to the longitudinal direction of the main body 100. The length of the cylindrical sleeve 75 is also substantially equal to the size of the part of the sealing lip 64 protruding from the main body 100 in the direction where the cylindrical sleeve 75 extends. mechanical pressing means 66 to exert effective pressure on the sealing lip.

[0150] When placing the leak detection bell 55 in the area to be tested, the mechanical pressure means 66 must be checked to ensure that it is properly pressed against the seal 60 in order to be able to properly test the weld seal. Therefore, one problem involves ensuring that the mechanical pressing means 66 properly performs its role around the peripheral sealing lip 64. However, the area to be examined, and in particular at the ends of the bell-shaped detection device 55, may be a connection area between a plurality of corrugated metal sheets. , for example, four corrugated metal sheets, so that the zone is not completely flat, but contains stages that make it difficult to press the seal 60.

[0151] FIG. 13 shows the bell-shaped detection device 55 according to the fourth embodiment, in which the mechanical pressing means 66 has been reinforced at the ends of the bell-shaped detection device 55 to overcome the unevenness of the area. The bell-shaped detection device 55 in FIG. 13 is constructed similarly to the bell-shaped detection device 55 in FIG. 8, but differs in particular with respect to the mechanical pressure means 66. Indeed, the bell-shaped detection device 55 in FIG. 13 includes a main body 100 extending in the longitudinal direction, a flexible seal 60 fixed to the main body 100, and a mechanical pressure means 66 supported by the main body and configured to exert pressure directed towards the membrane 5, 8 on the seal 60. However, the mechanical pressure the means 66 in this case comprises pressure elements 72 and end pressure elements 87.

[0152] Each pressing element 72 includes a curved strip 72, at least one end of which abuts against the base of the cavity 62. The curved strips 72, located between two adjacent depressions, for their part have one end located at the base of one of the indentations 65, and the other end located at the base of the other of the depressions 65. The pressure members 72 in this case, as illustrated in FIG. 14 are attached by fastening means 77, each of which contains a pin 83. Each pin 83 includes a shaft 85 freely mounted on the body 84. The shaft 85 includes an end abutting one of the curved strips 72. The body 84 is attached to the carrier 73. The pin 83 also includes a spring 86 connecting the stem 85 to the housing 84, the spring 86 acting between the housing 84 and the stem 85 to position the end of the stem 85 against the curved strip 72. Thus, the spring 86 is configured to actuate a response forces on the curved strip 72 so that the curved strip 72 presses the sealing lip 64 against the base of the corrugation.

[0153] The end pressure members 87 are located at the two ends of the sealing lip 64 in the longitudinal direction, that is, at the two ends of the bell-shaped leak detection device 55, given that the said device takes a generally longitudinal shape. The end pressure members 87 may be constructed according to a variety of separate alternative embodiments, which may or may not be able to be combined on the same bell-shaped leak detection device 55. For brevity, three alternative embodiments of end pressure members 87 are illustrated in FIG. 13 on the same bell-shaped leak detection device 55.

[0154] Figures 15-17 show three alternative embodiments of end pressure members 87. As shown in FIG. 15, according to a first alternative embodiment, the end pressure member 87 includes an end pin 88. Each end pin 88 includes a shaft 90 freely mounted on the body 89. An elongated support member 91 is attached to one end of the stem 90, with the elongated support member 91 abutting against a sealing lip 64. Body 89 is attached to bearing member 73. End pin 88 also includes a spring 86 connecting stem 90 to body 89, spring 86 acting between body 89 and stem 90 to position elongated bearing member 91 against sealing lip 64. Thus, the spring 86 is configured to exert a response force on the elongate seat 91 such that the elongate seat 91 presses the sealing lip 64 against the area to be tested. Thus, a counter force is applied to the sealing lip 64 along the entire length of the elongated support member 91. In the case of the first alternative embodiment of FIG. 15, each elongated support member 91 is attached to only one shaft 90 of the end pin 88.

[0155] A second alternative embodiment of the end pressure members 87 is illustrated in FIG. 16. The second alternative implementation differs from the first alternative implementation with respect to the elongated support element 91 of the end pins 88, the remaining features of the end pressure elements 87 are retained. In this alternative embodiment, an elongated support member 91 is attached to one end of the stem 90 of the first end pin 88 and to one end of the stem 90 of the second end pin 88 adjacent to the first end pin 88. Therefore, the elongated abutment member 91 is longer in this case than in the first alternative embodiment and is thus pressed by two end pins 88 distributed along its length so as to form a longer bearing surface on the sealing lip 64.

[0156] A third alternative embodiment of the end pressure members 87 is illustrated in FIG. 17. In this alternative embodiment, the end pressure member 87 includes a plurality of adjustment members 92 forming a series of members. The adjusting element 92 includes a rod 93 extending to the sealing lip 64 and perpendicular to the area to be tested, and an adjustable end 94 in the longitudinal direction of the rod so as to contact the sealing lip 64 after adjusting the rod 93. Thus, the end pressure element 87 can be more finely adjusted using the adjusting members 92 in order to more closely fit the area to be tested and hence improve the sealing of the detection chamber 61 .

[0157] The operation method of the bell-shaped leak detection device 65, as illustrated in FIG. 8, in the leak detection device 54, including the aforementioned bell-shaped device 65, the vacuum pump 57 connected to the detection chamber 61 through the gas outlet port 78, and the analysis apparatus 56 will be described below. The operation of such a detection device 54 allows the sealing of the weld bead 62 to be controlled between the two corrugated sheets of the sealing membrane 5, 8.

[0158] First, the detection bell 55 is placed in the area in which the seal is to be tested, in this case a portion of the weld bead 62, for example, by one or more operators through the handles 76. To this end, the main body 100 of the bell 55 detections are placed over the weld bead 62 so that the length of the main body 100 is aligned and centered with the weld bead 62. Thus, the sealing lip 64 is positioned on both sides of the weld bead 62 and completely encloses the area of the weld bead 62 to be tested in order to to form, with the main body 100 and the membrane 5, 8, a sealed detection chamber 61 as shown in FIG. 9.

[0159] After the detection bell 55 has been placed on the weld bead 62, the detection bell 55 spontaneously attaches to the membrane 5, 8 due to the vacuum force activated by the vacuum pump 57. This vacuum force then activates the mechanical pressing means 66 so that it redirected the pressure in order to press the sealing lip 64 against the membrane 5, 8 in certain well defined areas.

[0160] When the mechanical pressing means 66 experiences a force on the carrier 73, the carrier 73 retransmits the force to the curved bands 72 through their respective attachments, which tends to elastically deform the curved bands 72. For this reason, and through elastic return, the curved bands 72 transmitting force to the sealing lip 64 through the cylindrical bushings 75 to areas where the sealing lip is more likely to detach, namely the longitudinal ends of the main body 100 and the base of the troughs 65.

[0161] The vacuum pump 57 is then activated so as to create a vacuum in the detection chamber 61 through the channel 82 and the gas outlet channel 78. The flexibility of the sealing lip 64 causes it to deform during depressurization of the detection chamber 61, tending to reduce the volume of the detection chamber 61. Indeed, the sealing lip 64 thus approaches from both sides of the weld bead 62, as shown in FIG. 10. Once the pressure inside the detection chamber 61 falls below the pressure threshold value Ps, the gases present in the detection chamber 61 are transported to the apparatus 56 for analysis.

[0162] Thus, it is preferable that the sealing lip 64 takes two positions depending on whether it is located in its original state, that is, without the application of vacuum in the detection chamber 61, or in the working state when such a vacuum is applied.

[0163] In this initial state, the sealing lip 64 rests on the surface of the sealing membrane 5, 8 without any pressure, while in its operating state, at least one end portion of the sealing lip 64 is pressed under the main body 100 so that ideally seal the contour or periphery of the detection chamber 61 . Indeed, due to the flexibility of the sealing lip 64, said lip is pressed between the main body 100 and the membrane 5, 8 when a vacuum is applied. This positioning of the sealing lip 64 between the main body 100 thus collapsed or squeezed and the sealing membrane 5, 8 effectively helps achieve a perfect seal of the detection chamber 61, thus allowing a vacuum of at least 100 Pa (1 mbar) to be achieved and maintained. ), and even have lower pressure.

[0164] Thus, according to a preferred embodiment of the invention, the sealing lip 64 is in an operating state when a vacuum is applied in the detection chamber 61 in which a portion of the sealing lip 64 is held between the main body 100 and the sealing membrane 5, 8 on at least a portion of the periphery detection chamber 61, even around the entire periphery of said chamber 61.

[0165] The analysis apparatus 56 then analyzes, over a minimum time period Tm, the gas concentration of the gases present in the detection chamber 61 so as to reach a value representing the concentration evolution. This representative value is then compared with a threshold value, so as to determine whether or not a portion of the weld bead 62 under investigation has seal damage.

[0166] If the measured value is below the threshold value, then it is concluded that the part to be tested has no seal damage, in which case the detection bell 55 is then positioned facing the adjacent area of the weld bead 62, by forming a coating between the two successively tested areas to ensure that the seal of the weld bead 62 was tested along the entire length of said weld bead 62.

[0167] If the measured value is greater than or equal to the threshold value, then it is concluded that the test portion of the weld bead 62 has seal damage. Then, corrective welding measures are taken to repair the damage. Measures using an additional detection tool may also be envisaged in order to more accurately localize the location of seal failure.

[0168] In another embodiment not shown, various features of the previous embodiments may be combined together. Indeed, for example, the mechanical pressing means 66 in FIG. 8 can be adapted to seal 60 in FIG. 5 deviation of the location of the curved strips 72.

[0169] The bell-shaped detection device, the detection device, and the operation method of the device described above are specifically for testing the membrane seal of a sealed and heat-insulating membrane tank. As an example, such membrane reservoirs are specifically disclosed in patent applications WO 14057221, FR 2691520.

[0170] Membrane tanks have a plurality of walls that are of a sandwich construction as shown in FIG. 11. Each wall 1 contains, from the outside to the inside of the tank, an auxiliary heat barrier 2 containing auxiliary insulation panels 3 fixed to the supporting structure 4, an auxiliary membrane 5 which rests on the auxiliary heat barrier 2, the main heat barrier 6 containing main insulating panels 7, which rest on the auxiliary membrane 2, and fixed on the supporting structure 4 or on the auxiliary insulating panels 3, and the main membrane 8, which rests on the main heat-insulating barrier 6 and which is intended to contact with the liquefied gas contained in the tank.

[0171] The reservoir has a generally multifaceted shape. In the embodiment illustrated in FIG. 12, the reservoir has a front wall 9 and a back wall, not shown, which in this case have an octagonal shape. The tank also includes a top wall 10, a bottom wall 11 and side walls 11, 12, 13, 14, 15, 16, 17, which extend in the longitudinal direction of the tank between the front wall 9 and the rear wall.

[0172] Auxiliary heat-insulating barriers 2 of the walls of the tank are connected together so as to form, between the support structure 4 and the auxiliary membrane 5, an auxiliary sealed heat-insulating space. Similarly, the main heat insulating barriers 6 of the tank walls are connected together so as to form, between the auxiliary membrane 5 and the main membrane 8, a sealed main heat insulating space.

[0173] At least one of the main 8 and auxiliary 5 membranes contains a plurality of metal sheets that are welded together. The seal test method, which will be described more specifically here, is for testing sealed welds for joining metal sheets together. According to one embodiment, the membrane to be tested has corrugations that allow it to deform under the action of thermal and mechanical stresses created by the fluid stored in the reservoir. For this, as shown, for example, in Fig. 8, each metal sheet contains two rows of corrugations which are perpendicular to each other.

[0174] In one embodiment, the seal test method comprises three steps, namely:

- diffusion of indicator gas in the heat-insulating space covered with membrane 5, 8, for which the seal must be investigated;

- control of indicator gas diffusion in the heat-insulating space; and

- checking the sealing of the welds of the membrane 5, 8.

[0175] In another embodiment, the seal test method comprises only the step of testing the seal of the membrane welds 5, 8 without the use of a tracer gas.

[0176] The step of diffusing the tracer gas includes injecting the tracer gas into the heat-insulating space which is covered by the membrane 5, 8 for which the seal is to be checked. When the seal of the auxiliary membrane 5 is about to be checked, a tracer gas is injected into the auxiliary heat-insulating space. In this case, the seal test method is carried out before the main heat barrier 7 and the main membrane 8 are installed. When the seal of the main membrane 8 is about to be tested, a tracer gas is injected into the main heat shield space.

[0177] FIG. 12 schematically illustrates a sealed and heat-insulated tank, as well as a system for injecting tracer gas into the heat-insulating space.

[0178] The injection system comprises a plurality of channels 18, which, on the one hand, are connected to a tracer gas source, not illustrated, and, on the other hand, are connected to a tracer gas injection device 19, providing a path for injecting tracer gas through the membrane 5, 8 , for which the compaction is to be investigated. More specifically, the tracer gas injection devices 19 provide passages of the tracer gas through the bottom wall membrane 11. This arrangement is particularly advantageous because the vapor density of the tracer gas is lower than that of air, so that it tends to rise in the heat-insulating space. Therefore, injecting the tracer gas from below through the membrane 5, 8 to be examined of the bottom wall 11 allows the tracer gas to quickly and uniformly diffuse into the heat-insulating space.

[0179] In the embodiment shown in FIG. 12, the bottom wall 11 is provided with at least four tracer gas injection devices 19 which are evenly distributed over the surface of the bottom wall 11. The bottom wall 11 is rectangular in shape and can thus be divided into four surface zones that are equal on their two axes. symmetries x and y. Each of the four tracer gas injection devices 19 is located in one of the four aforementioned zones. In the illustrated particular embodiment, each tracer gas injection device 19 is located near the center of its respective zone. In a particular embodiment, each of the four tracer gas injection devices is located at a distance of 1/4L from the adjacent longitudinal edge and at a distance of 1/4B from the adjacent transverse edge, with L being the longitudinal dimension of the bottom wall 11 and B being the transverse dimension of the bottom walls 11.

[0180] The step of controlling the diffusion of the tracer gas includes, when the tracer gas diffuses through the heat-insulating space, controlling the diffusion of the tracer gas in the heat-insulating space.

[0181] To this end, a plurality of gas samplers are used to take a sample of the gas contained in the heat-insulating space where tracer gas was injected, the samplers being provided through a membrane covering said heat-insulating space. Each sampler is connected to an analysis apparatus, such as a mass spectrometer, which allows checking the presence and concentration of tracer gas in the corresponding zone of the thermal insulation space.

[0182] The step at which the welds are checked includes the use of the previously presented leak detection device 54 on one of the membranes 5, 8 of the sealed and insulated tank.

[0183] Although the invention has been described in relation to many specific embodiments, it is obvious that it is in no way limited to them, and that it contains all technical equivalents of the described means, as well as their combination, if they fall within the scope of the invention.

[0184] The use of the verb "comprise" or "include" and their conjugated forms does not preclude the presence of other elements or steps other than those set forth in the claims.

[0185] In the claims, any reference position in parentheses cannot be construed as a limitation of the claims.

Claims (33)

1. Bell-shaped device (55) leak detection for leak detection in the area (62) testing the sealing membrane (5, 8) of the tank containing the main body (100), designed to be placed in the test area (62), seal (60) connected to the main body (100) and configured to limit the detection chamber (61) between the main body (100) and the test area (62), while the seal (60) contains a peripheral sealing edge (64) having closed circuit to cover the area (62) of the test, mechanical pressure means (66) supported by the main body (100) and containing at least one pressure element (72) configured to exert pressure on the portion of the sealing edge (64) directed towards the membrane (5, 8) when the main body (100) is located in the test area (62), moreover, the sealing edge (64) contains at least a cavity (65), the shape of which corresponds to the shape of the corrugation of the membrane (5, 8), while the cavity (65) is designed to cover the corrugation, and the pressing element (72) is configured to locally press the sealing lip into the area of said sealing lip (64) which is located at the base of the cavity (65). 2. The bell-shaped leak detection device (55) according to claim 1, wherein the pressure member (72) is an elastically deformable member that exerts pressure on a portion of the sealing lip (64) by elastic deformation. 3. A bell-shaped leak detection device (55) according to claim 1 or 2, in which the pressure element (72) is oriented perpendicular to the contour of the peripheral sealing lip (64). 4. The bell-shaped leak detection device (55) according to any one of the preceding claims, wherein the sealing lip (64) is configured such that, in operation, when a vacuum is applied in the detection chamber (61), a portion of said sealing lip (64) is held between the main body (100) and the sealing membrane (5, 8) on at least part of the periphery of the detection chamber (61), preferably around the entire periphery of said chamber (61). 5. The bell-shaped leak detection device (55) according to any one of the preceding claims, wherein the bell-shaped leak detection device (55) has an elongated shape, the length of which is greater than or equal to 0.5 m. 6. The bell-shaped leak detection device (55) according to claim 5, in which the mechanical pressure means (66) comprises a plurality of pressure elements (72) configured to apply pressure to a plurality of sections of the sealing lip (64), the sections being located at two ends sealing lip (64) in the longitudinal direction. 7. Bell-shaped device (55) leak detection according to any one of paragraphs. 1-6, in which the mechanical pressing means (66) comprises a plurality of pressing elements (72) configured to exert pressure on a plurality of sections of the sealing lip (64), the sections being located at the bases of the cavity (65). 8. Bell-shaped device (55) leak detection according to any one of paragraphs. 1-7, in which all sections of the sealing edge (64) located at the bases of the depressions (65) are pressed by a plurality of pressure elements (72) of the mechanical means (66). 9. Bell-shaped device (55) leak detection according to any one of paragraphs. 1-8, in which the sealing edge (64) contains at least two depressions, and the pressure elements (72) contain a curved strip, the two ends of which abut against the base of two adjacent depressions (65). 10. A bell-shaped leak detection device (55) according to any one of the previous claims, in which the pressure element (72) comprises a curved strip containing at one of its ends, which is in contact with the sealing edge (64), a cylindrical sleeve (75). 11. The bell-shaped leak detection device (55) according to any one of the preceding claims, wherein the seal (60) is made of an elastomeric material with a Shore A hardness of 20 to 50. 12. The bell-shaped leak detection device (55) according to claim 11, wherein the elastomeric material of the seal (60) is selected from polyurethane elastomer and EPDM rubber. 13. The bell-shaped leak detection device (55) according to any one of the previous claims, in which the main body (100) comprises a rigid central part (59), and in which the seal (60) comprises a casing (63) hermetically attached to the peripheral wall of the rigid central part (59). 14. Bell-shaped leak detection device (55) according to claim 13, in which the rigid central part (59) contains a recess (79) on the bottom surface (80) which is designed to pivot towards the test zone (62). 15. The bell-shaped device (55) for detecting leakage according to claim 14, in which the rigid central part (59) contains a channel (82) connecting the recess (79) with the upper surface (81) of the rigid central part (59) for attaching a vacuum pump ( 57). 16. Leak detection device (54) for testing the seal of the membrane (5, 8) of a sealed and heat-insulating tank, containing bell-shaped device (55) leak detection according to any one of paragraphs. 1-15, vacuum pump (57) connected to detection chamber (61), an analysis apparatus (56) connected to the detection chamber (61) to analyze the amount of gas present in the detection chamber (61). 17. Method of operation of the leak detection device (54) according to claim 16 in the area (62) of testing the sealing membrane (5, 8) of the tank, which includes the following steps, in which: place the bell-shaped detection device (55) in the test area (62) so that the sealing edge (64) completely covers the test area (62), applying pressure to the sealing lip (64) using a mechanical pressure means (66) to press the sealing lip (64) against the sealing membrane (5, 8), depressurize the detection chamber (61) by means of a vacuum pump (57), supply gases present in the detection chamber (61) to the apparatus (56) for analysis, and analyzing by means of the analysis apparatus (56) the gases emanating from the detection chamber (61), and providing a variable representing the gases present in the detection chamber (61). 18. The method of operation according to claim 17, wherein the leak detection bell (55) is oriented in the test area (62) so that the length of the leak detection bell (55) overlaps with the test area (62). 19. The method of operation according to claim 17 or 18, in which the test zone (62) is part of the welded bead (62) of the sealing membrane (5, 8). 20. The method of operation according to any one of paragraphs. 17-19, in which the test area (62) is placed on a corrugated sealing membrane (5, 8).

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