Method for installing a tank wall sealing membrane, and corresponding positioning tool

Abstract

The invention relates to a method for installing a sealing membrane 12 on the wall 2 of a liquefied gas storage tank 1, comprising: - providing a thermally insulating barrier 4, comprising two juxtaposed insulating panels 10 having a groove 20; - inserting a welding support 25 into the groove 20 of a first insulating panel 10; - inserting a positioning tool 30, having a flared channel 36, into the ends 21 of the grooves 20, aligned with the grooves 20; - inserting the welding support 25 into the flared channel 36 and then into the second insulating panel 10; - welding a welt 26 of the sealing membrane 12 onto the welding support 25. The invention also relates to a positioning tool 30 for installing the sealing membrane 12. Figure for the abstract: 5

Description

Title of the invention: Method for installing a tank wall sealing membrane, and corresponding positioning tool. Technical field

[0001] The invention relates to the field of leak-proof and thermally insulated membrane tanks. In particular, the invention relates to the field of leak-proof and thermally insulated tanks for the storage and / or transport of liquefied gases at low temperatures, such as tanks for transporting Liquefied Petroleum Gas (also called LPG) at temperatures ranging, for example, from -50°C to 0°C, or for transporting 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 used for transporting liquefied gas or for receiving liquefied gas to serve as fuel for the propulsion of the floating structure. Technological background

[0002] Document FR 3077115 Al discloses a sealed and thermally insulated liquefied natural gas storage tank arranged in a load-bearing structure and whose walls have a multilayer structure. The multilayer structure comprises, from the outside to the inside of the tank, a secondary thermally insulating barrier anchored against the load-bearing structure, a secondary sealing membrane which is supported by the secondary thermally insulating barrier, a primary thermally insulating barrier which is supported by the secondary sealing membrane, and a primary sealing membrane which is supported by the primary thermally insulating barrier and which is intended to be in contact with the liquefied natural gas stored in the tank.

[0003] Each thermally insulating barrier comprises juxtaposed insulating panels. The insulating panels are formed by a stack of components, for example, a block of polymer foam arranged between two rigid plates. For each thermally insulating barrier, one of these two rigid plates is located towards the inside of the tank and the other towards the outside of the tank. The rigid plate located towards the inside of the tank, called the inner plate, supports the corresponding sealing membrane. For this purpose, the inner plate is provided with grooves that accommodate weld supports in the form of L-shaped folded metal strips. In addition, struts, which are metal plates belonging to the sealing membrane, are welded onto the weld supports.

[0004] During tank assembly, the welding supports are positioned in the ribs. Specifically, the welding supports, which are elongated elements, are progressively slid into the grooves of the insulation panels. To facilitate the insertion of the welding supports into the gap between adjacent insulation panels, notches are provided at the ends of the grooves. However, in the prior art, inserting these welding supports is tedious and requires the operator to regularly check the correct alignment of the welding support in the groove. Summary of the invention

[0005] Indeed, the inventors have observed that the welding supports curve towards one side of the notches during insertion, thus blocking insertion and risking damage. Sliding at the ends of the insulating panels is therefore hindered.

[0006] An idea at the basis of the invention is to propose a positioning tool and an installation method which make it easy to install welding supports for fixing a sealing membrane in a sealed and thermally insulating tank wall, and which are simple and inexpensive to implement.

[0007] According to one embodiment, the invention provides a method for installing a sealing membrane for a tank wall for a sealed and thermally insulating tank for the storage of a liquefied gas, the tank wall comprising a thermally insulating barrier and said sealing membrane resting against said thermally insulating barrier; in which the process comprises the following steps: - provide the thermally insulating barrier, which comprises a first insulating panel and a second insulating panel juxtaposed to the first insulating panel, each having a top plate defining a support surface against which the sealing membrane rests, the top plates of the first and second insulating panels each having at least one groove, the grooves of the first and second juxtaposed insulating panels being aligned and extending in a longitudinal direction, each groove opening at the level of the support surface and having in the thickness of the thermally insulating barrier an entry zone and a retention zone disposed under the entry zone and which extends parallel to the support surface, one dimension of the retention zone in a transverse direction being greater than one dimension of the entry zone in the transverse direction;each groove of the first and second juxtaposed insulating panels having, opposite the other among the first and second insulating panels, a notched end, the dimension in the direction; transverse of the entry zone being widened at the notched end; the notched ends of the two juxtaposed insulating panels together forming an elongated recess in the longitudinal direction; - provide a welding support comprising a welding wing and an anchoring wing inclined relative to the welding wing; - to slide said welding support into the groove of the first insulating panel between the first and second insulating panels, until a retention state is reached in which the anchoring wing is retained in the retention area of ​​said groove of the first insulating panel; - insert a positioning tool into the elongated recess, the positioning tool comprising a first peripheral wall and a second peripheral wall spaced from the first peripheral wall in the transverse direction by a flared channel extending in the longitudinal direction, the flared channel opening on one side through an insertion hole, and on the other side through a release hole, the flared channel having a dimension in the transverse direction decreasing from the insertion hole to the release hole, the flared channel being aligned with the groove of the first insulating panel, the insertion hole being opposite the groove of the first insulating panel; - slide the welding support into the flared channel from the insertion hole to the release hole; - slide the welding support into the groove of the second insulating panel; - place a strake of the sealing membrane on the support surface, the strake being a profiled piece extending along the longitudinal direction and whose cross-section has a flat median portion resting on the support surface and at least one raised lateral edge projecting from the support surface, - fix the lateral edge of the strake, by welding, to the weld flange of the weld support.

[0008] Thanks to these features, it is possible to easily align the welding support with a groove into which it is to be inserted, particularly when passing between two adjacent insulation panels. The user does not have to interrupt operations to compensate for any lateral deformation the welding support may undergo and guide it into the next groove. Given the potentially very large number of insulation panels in a liquefied gas storage tank, this results in significant time savings during assembly and related cost reductions.

[0009] Furthermore, the flared shape of the channel allows the user to directly detect the orientation to be given to the positioning tool.

[0010] According to embodiments, such an installation method may include one or more of the following characteristics.

[0011] According to one embodiment, the first peripheral wall and the second peripheral wall have an external contour with a shape correspondence with a contour of the elongated recess.

[0012] Thus, this results in good insertion and good retention of the positioning tool in the elongated recess.

[0013] According to one embodiment, the positioning tool comprises a stop surface bearing against the support surface when the positioning tool is inserted into the elongated recess, in which at least one of the first and second peripheral walls has, in a depth direction perpendicular to the support surface, a dimension less than one dimension, in the depth direction, of the entry zone between the support surface and the retention zone.

[0014] Such a dimension advantageously allows the anchoring portion of the welding support to slide in the grooves without hitting any peripheral wall.

[0015] According to one embodiment, the first and second peripheral walls each have, in the depth direction, a dimension less than one dimension, in the depth direction, of the entry zone between the support surface and the retention zone.

[0016] Thus, the installation method can be carried out regardless of which side the anchoring portion of the welding support extends into the retention area of ​​the grooves.

[0017] According to one embodiment, the thermally insulating barrier comprises a third insulating panel, juxtaposed to the second insulating panel, which has a top plate defining together with the top plates of the first and second insulating panels the support surface against which the sealing membrane rests, the top plate of the third insulating panel having at least one groove, aligned with at least one groove of the second insulating panel and extending in the longitudinal direction, the groove of the third insulating panel opening at the level of the support surface and having in the thickness of the thermally insulating barrier an entry zone and a retention zone disposed under the entry zone and which extends parallel to the support surface, one dimension in the transverse direction of the retention zone being greater than one dimension in the transverse direction of the entry zone;each groove of the second and third insulating panels placed side by side having, opposite the third or second insulating panel, a notched end, the dimension in the transverse direction of the entry area being widened at the notched end; the notched ends of the second and third insulating panels placed side by side jointly forming a second elongated recess in the longitudinal direction, the elongated recess jointly formed by; the notched ends of the first insulating panel and the second insulating panel placed side by side forming a first elongated recess, in which the process includes the following steps, prior to the step of placing the edge of the sealing membrane on the support surface: - remove the positioning tool from the first elongated recess; - insert the positioning tool into the second elongated recess, the flared channel being aligned with the groove of the second insulating panel, the insertion hole being opposite the groove of the second insulating panel; - Slide the welding support into the flared channel from the insertion hole to the release hole, - Slide the welding support into the groove of the third insulating panel.

[0018] The positioning tool is thus reusable successively from one elongated recess to the next.

[0019] According to one embodiment, the invention also provides a positioning tool, which includes a gripping portion and an insertion portion extending from the gripping portion, the insertion portion having a first peripheral wall and a second peripheral wall separated from the first peripheral wall by a flared channel extending in a longitudinal direction, the flared channel opening on one side through an insertion orifice, and on the other side through a release orifice, the flared channel having a dimension in a transverse direction which is perpendicular to the longitudinal direction, decreasing from the insertion orifice to the release orifice, in which the gripping portion connects the first peripheral wall and the second peripheral wall, the gripping portion being configured to serve as a gripping means for an operator.

[0020] Such a tool advantageously makes it possible to compensate for any lateral deformation that a welding support undergoes, in order to be able to easily insert it into the next groove.

[0021] According to one embodiment, the positioning tool has a U-shaped section in a plane normal to the longitudinal direction, the flared channel being open on one side opposite the grasping portion, between the insertion orifice and the release orifice.

[0022] The peripheral walls of the insertion portion are thus separated from each other and allow the passage of the weld wing.

[0023] According to one embodiment, the positioning tool comprises a first stop surface extending in a stop plane defined by the longitudinal direction and the transverse direction, the first peripheral wall projecting from the stop surface in a depth direction perpendicular to the stop plane.

[0024] Such a stop surface allows the positioning tool to be positioned in a certain and stable manner against the support surface when the positioning tool is inserted into the elongated recess.

[0025] According to one embodiment, the positioning tool comprises a second stop surface extending in the stop plane, the second peripheral wall projecting from the second stop surface in the depth direction. Preferably, the first stop surface and the second stop surface are coplanar.

[0026] Such a second stop surface allows the positioning tool to be placed even more stably against the support surface.

[0027] According to one embodiment, a first height is defined in the depth direction between the first stop surface and a distal end of the first peripheral wall opposite the first stop surface, a second height being defined in the depth direction between the first stop surface and a distal end of the second peripheral wall opposite the first stop surface, the first height being equal to the second height.

[0028] Thus, the positioning tool can be used regardless of which side the anchor portion of the weld support extends into the groove retention area, without hindering the sliding of the anchor portion through the elongated recess.

[0029] According to one embodiment, the first and second peripheral walls jointly define an oblong contour. The positioning tool can thus ideally correspond in shape to an elongated oblong recess when the notched ends of the grooves are rounded by milling along the depth direction. Brief description of the figures

[0030] The invention will be better understood, and other objects, details, features and advantages thereof will become more apparent from the following description of several particular embodiments of the invention, given solely by way of illustration and not limitation, with reference to the accompanying drawings.

[0031] Fig. 1 is a partial perspective view of a sealed and thermally insulating tank wall.

[0032] Fig. 2 is a schematic top view of the end of two insulating panels that make up the tank wall of Fig. 1, facing each other.

[0033] Fig. 3 is a cross-sectional view of a groove in an insulating panel of Fig. 1, and of a junction area between a welding support, inserted in the groove, and two strakes of a sealing membrane.

[0034] Fig. 4 is a perspective view of a welding support forming and dispensing machine of Fig. 3.

[0035] Fig. 5 is a side perspective view of a positioning tool according to one embodiment.

[0036] Fig. 6 is a bottom view of a welding support positioning tool of Fig. 5.

[0037] Fig. 7 is a side view of a positioning tool according to another embodiment. Description of the implementation methods

[0038] Figure 1 illustrates a tank 1, which is a membrane tank for storing liquefied gas. The tank 1 has a wall 2 with a multilayer structure. The wall 2 comprises, from the outside in, a load-bearing structure 3, a secondary thermally insulating barrier 4 with insulating panels 10 resting against the load-bearing structure 3, a secondary sealing membrane 12 resting against the secondary thermally insulating barrier 4, a primary thermally insulating barrier 5 with insulating panels 100 resting against the secondary sealing membrane 12, and a primary sealing membrane 120 intended to be in contact with the liquefied gas contained in the tank 1. The primary sealing membrane 120 defines an internal space (not shown) intended to receive the liquefied gas.For example, such membrane tanks are described in particular in patent applications WO2019239048, WO14057221, FR2691520 and FR2877638.

[0039] The liquefied gas intended to be stored in tank 1 may, in particular, be liquefied natural gas (LNG), that is to say, a gaseous mixture consisting mainly of methane and one or more other hydrocarbons. The liquefied gas may also be ethane or liquefied petroleum gas (LPG), that is to say, a mixture of hydrocarbons from petroleum refining consisting essentially of propane and butane.

[0040] For the sake of simplicity, the following description refers to the secondary thermally insulating barrier 4, including its insulating panels 10, described with reference to [Fig. 1], and its sealing membrane 12, described with reference to [Fig. 3]. It can, however, be transposed by analogy to the primary thermally insulating barrier 5, including its insulating panels 100 and its sealing membrane 120.

[0041] As illustrated in [Fig. 1], the insulating panels 10 are generally parallelepiped in shape and are placed side by side to also form a support for a respective sealing membrane. When the insulating panels 10 are placed side by side, a channel 19, visible in [Fig. 2], is provided between them to compensate for manufacturing tolerances and facilitate assembly. The channel 19 is filled during the installation of the thermally insulating barrier 4 with a fibrous pad, for example, made of glass wool, so as to restore its sealing and insulating function.

[0042] An insulating panel 10 may comprise a first plate 15, a second plate 17, and a polymer foam block 16. The first plate 15 is oriented towards the tank's supporting structure, while the second plate is oriented towards the inside of the tank. The first plate 15 and the second plate 17 are rigid plates, for example, made of plywood. The polymer foam block 16 is sandwiched between the first plate 15 and the second plate 17. The insulating panel 10 has four lateral faces 13 and 14, parallel to each other in pairs. The lateral faces 13 are opposite each other and each is perpendicular to the two lateral faces 14.

[0043] The second plate 17 has a pair of grooves 20. The grooves 20 extend in a straight line and parallel to each other, between the transverse faces 14. The grooves 20 here have an inverted T-shaped section. The groove 20 thus has an inlet zone 201 and at least one retention zone 202. The inlet zone 201 extends substantially along a depth direction of the wall 2 of the tank 1 and opens at a support surface 18 of the second plate 17, opposite the polymer foam block 16. The depth direction is defined within the thickness of the wall 2 of the tank 1. The retention zone 202 extends along a plane orthogonal to the depth direction of the wall 2 of the tank 1. A retention portion 203 is thus provided in the second plate 17, between the support surface 18 and the retention zone 202.

[0044] As can be seen in [Fig.2], each groove 20 opens at the end of the second plate 17 through a notched end 21, at the level of one of the lateral faces 14. The dimension in the transverse direction of the entry zone 201 is widened at the notched end 21. Preferably, the dimension in the transverse direction of the entry zone 201 at the notched end 21 is equal to the dimension in the transverse direction of the retention zone 202.

[0045] When two insulating panels 10 are placed side by side, the grooves 20 of these two insulating panels 10 are aligned with each other, and the notched ends 21 of the first of the two insulating panels 10 are positioned opposite the notched ends 21 of the second insulating panel 10. The notched ends 21 opposite Screws in pairs thus form elongated recesses 210. Such a recess is illustrated in [Fig.2],

[0046] Here, the notched ends 21 are rounded, not limited to, and the recesses 210 are oblong in shape.

[0047] As seen in [Fig.3], the primary and secondary sealing membranes 12 each comprise a continuous layer of weld supports 25 and strakes 26.

[0048] Such a weld support 25 has a weld flange 251 and an anchor flange 252. The weld flange 251 and the anchor flange 252 are inclined relative to each other, for example, perpendicular to each other. The weld flange 251 and the anchor flange 252 thus give the weld support 25 an L-shaped cross-section.

[0049] The welding supports 25 are installed parallel to each other and retained in the grooves 20 of the juxtaposed insulating panels 10. The anchoring flange 252 of the welding support is inserted inside the retention zone 202 of the groove 20, while the welding flange 251 passes through the entry zone 201 extending in the depth direction of the wall 2 of the tank 1 so as to protrude into the tank 1, beyond the second plate 17. The anchoring flange 252 is thus retained against the retention portion 203, which allows the welding supports 25 to be anchored to the insulating panels 10. The grooves 20 of the insulating panels 10 are aligned one after the other in a longitudinal direction x, preferably parallel to the lateral faces 13.Thus, a welding support 25 extends along the longitudinal direction x, substantially from one end to the other of the wall 2 of tank 1, passing through the grooves 20 aligned with each other in a plurality of juxtaposed insulating panels 10.

[0050] The strakes 26 are profiled metal parts. The strakes 26 have a flat central portion 261 and raised lateral edges 262.

[0051] In the assembled state of the tank, the flat central portion 261 of the strakes rests against the support surface 18 of the second plates 17. The raised lateral edges 262 extend along the longitudinal direction x and project from the flat central portion 261 towards the interior of the tank. The raised lateral edges 262 of the two strakes 26 that extend on either side of the weld support 25 are welded to the weld flange 251 of said weld support 25, preferably by means of a respective weld bead 263.

[0052] A tooling system 11, dimensioned for the placement of weld supports 25, is described with reference to figures 4 to 7. The tooling system 11 comprises a forming and dispensing machine 23 and a positioning tool 30.

[0053] First, the forming and dispensing machine 23 is described with reference to [Fig.4],

[0054] The machine 23 here includes a support 231 for a roll 24 of raw metal strip 250. In the illustrated example, the support 231 has a plurality of pins 232, defining a recess, and an axle 233, at the center of the recess. The machine 23 also includes a forming nozzle 235. Finally, the machine preferably also includes a pair of flanges 234. The forming nozzle 235 is then arranged between the flanges 234, which limits access to the forming nozzle 235 by users, and therefore the risk of accidents.

[0055] The machine 23 forms the weld support 25 from the raw metal strip 250 and distributes the weld support 25 thus formed. For this purpose, the roller 24 is installed on the shaft 233 so as to rest on the support 231. The raw metal strip 250 is fed into the forming nozzle 235, here between the cheeks 234. The passage of the raw metal strip 250 through the die 235 forms the aforementioned weld wing 251 and anchor wing 252 of the weld support 25. The weld support 25 is thus ready for distribution and can be inserted into one of the grooves 20.

[0056] The positioning tool 30 is now described with reference to Figures 5 to 7.

[0057] The positioning tool 30 comprises an input portion 31 and a portion Insertion portion 32. The gripping portion 31 serves as a handle for the positioning tool 30. The insertion portion 32 is designed to fit into an elongated recess 210, so as to ensure the correct placement of the positioning tool 30 itself relative to the insulating panels 10. For this purpose, the insertion portion 32 has a contour that corresponds in shape to the elongated recess 210. In the illustrated embodiment, the contour of the insertion portion 32 is generally oblong in shape.

[0058] The gripping portion 31 is here, but not limited to, generally parallelepiped in shape. The gripping portion 31 thus has a pair of first end surfaces 40. At least one of the end surfaces 40 forms a stop surface and is intended to come into contact with the support surface 18 when the positioning tool 30 is inserted into the elongated recess 210. The end surfaces 40 preferably extend in the same stop plane P, visible in [Fig. 5], defined by the longitudinal direction x and a transverse direction y normal to the longitudinal direction x in the plane of the support surface 18, when the positioning tool 30 is inserted into an elongated recess 210. The gripping portion 31 also has five lateral surfaces 41, 42, 43, 44 and 45, each of which is, but not limited to, planar.

[0059] A first lateral surface 41 and a second lateral surface 42 are opposite each other. The first lateral surface 41 and the second lateral surface 42 are transverse, and preferably perpendicular, to the end surfaces 40. A An insertion orifice 410 and a release orifice 420 are formed respectively on the first lateral surface 41 and the second lateral surface 42.

[0060] A third lateral surface 43 and a fourth lateral surface 44 are arranged transversely to the first lateral surface 41 and the second lateral surface 42. Finally, a fifth lateral surface 45 extends transversely to the lateral surfaces 41 to 44 opposite the end surfaces 40.

[0061] The insertion portion 32 comprises two peripheral walls 33. The peripheral walls 33 of the insertion portion 32 each project outward from a respective end surface 40. The end surfaces 40 and the peripheral walls 33 are separated from each other by a flared channel 36.

[0062] The flared channel 36 extends between the insertion port 410 and the release port 420 in the longitudinal direction x. The flared channel 36 is delimited by a pair of inclined surfaces 38, facing each other, and by a bottom surface 37, transverse to the inclined surfaces 38. The flared channel 36 thus has a U-shaped cross-section, open on one side opposite the bottom surface 37. The insertion port 410 is wider than the release port 420. One dimension of the flared channel 36 decreases in the transverse direction y from the insertion port 410 to the release port 420.

[0063] The flared channel 36 separates the insertion portion 32 into two peripheral walls 33. The peripheral walls 33 each extend from a respective end surface 40 of the grasping portion 31, in a direction opposite to the grasping portion 31. The peripheral walls 33 here each extend to a proper distal end 39, for example a distal surface which is parallel to the end surface 40, as illustrated in [Fig.5].

[0064] Each peripheral wall 33 extends between one of the inclined surfaces 38 of the flared channel 36 and an external face 34, opposite the respective inclined surface 38. The external face 34 here comprises a flat section 341 and two rounded sections 342, on either side of the flat section 341. The rounded sections 342 are each contiguous with the respective inclined surface 38. The external faces 34 of the pair of peripheral walls 33 together give the insertion portion 32 a generally oblong shape.

[0065] The elongated shape of the insertion portion 32 allows its simple insertion into the corresponding elongated shape of the elongated recesses 210. The placement of the positioning tool 30 against the insulating panels 10 then makes it possible to guide the welding support 25 from the groove 20 of a first insulating panel 10 to the groove 20 of a second insulating panel 10 in a particularly simple way.

[0066] In the embodiment illustrated in [Fig. 5], the two peripheral walls 33 are of the same height H, in the depth direction z, between a first surface end 40, forming a buttress surface, and a respective distal end 39 opposite the first end surface 40.

[0067] In the embodiment illustrated in [Fig.7], a first peripheral wall 33 has a height Hl, and a second peripheral wall 33 has a height H, in the depth direction z, between the first end surface 40, forming a stop surface, and a respective distal end 39 opposite the first end surface 40, Hl being less than the height H.

[0068] A depth D of the flared channel 36 is defined in the depth direction z between a bottom wall 37 of the flared channel 36 and a distal end 39 furthest from the first stop surface 40 among the distal end 39 of the first peripheral wall 33 and the distal end 39 of the second peripheral wall 33.

[0069] The depth D is strictly greater than each of the height H of the first peripheral wall 33 and the height H, respectively H1, of the second peripheral wall 33.

[0070] Furthermore, at least one of the first and second peripheral walls 33, preferably both, has, in the depth direction, a height H less than a dimension E of the entry zone 201, visible in [Fig.3], between the support surface 18 and the retention zone 202. This relationship allows the positioning tool 30 not to interfere with the weld support 25 in the retention zone 202.

[0071] A method for installing the sealing membrane 12 of the wall 2 of tank 1 may include the following steps:

[0072] - provide the thermally insulating barrier 4, which comprises at least two juxtaposed insulating panels 10, preferably three, even more preferably four or more, each of which has a top plate, such as the second plate 17;

[0073] - provide a soldering support 25;

[0074] - slide said welding support 25 into the groove 20 of the first insulating panel 10 of the two juxtaposed insulating panels 10, until a state of retention in which the anchoring wing 252 of the welding support 25 is retained in the retention zone 202 of said groove 20;

[0075] - insert a positioning tool 30 into the elongated recess 210, the flared channel 36 being aligned with the groove 20 of the first insulating panel 10, the insertion hole 410 being opposite the groove 20 of the first insulating panel 10;

[0076] - slide the anchor wing 252 of the weld support 25 into the flared channel 36 from the insertion port 410 to the release port 420;

[0077] - slide the welding support 25 into the groove 20 of the second insulating panel 10;

[0078] - place a strut 26 of the sealing membrane 12 on the support surface 18;

[0079] - to fix a raised lateral edge 262 of the strake 26, by welding, onto the anchor flange 252 of the welding support 25.

[0080] The positioning tool 30 can then be removed for use on a neighboring insulating panel 10, for example at the intersection between the second insulating panel 10 and a third insulating panel 10.

[0081] Alternatively, a plurality of positioning tools 30 is provided and used in the process of installing the sealing membrane 12 so as to limit the number of removal operations and the back and forth between the meeting areas between the pairs of neighboring insulating panels 10.

[0082] In the embodiment shown in Figures 5 and 6, the length of the peripheral walls 33 is less than the distance between the faces 41 and 42. Such dimensioning allows for good handling of the positioning tool 30.

[0083] In an alternative not shown, the dimensions of the positioning tool 30 may differ from those of the embodiment shown above. For example, the gripping portion 31 may be smaller, so that the peripheral walls 33 extend to the faces 41 and 42, and / or along the entire length of the flared channel 36.

[0084] The technique described above for producing a sealing membrane can be used in different types of tanks, for example to constitute the primary or secondary sealing membrane of an LNG tank in an onshore installation or in a floating structure such as an LNG carrier or other.

[0085] Although the invention has been described in connection with several particular embodiments, it is clearly evident that it is by no means limited to them and that it includes all technical equivalents of the means described as well as their combinations if these fall within the scope of the invention.

[0086] The use of the verb "comprise", "comprendre" or "include" and its conjugated forms does not exclude the presence of other elements or other steps than those stated in a claim.

[0087] In the claims, any reference sign in parentheses shall not be interpreted as a limitation of the claim.

Claims

1. Demands Method of installing a sealing membrane (12; 120) of a tank wall (2) for a sealed and thermally insulated storage tank for a liquefied gas (1), the tank wall (2) comprising a thermally insulating barrier (4; 5) and said sealing membrane (12; 120) resting against said thermally insulating barrier (4; 5); in which the process comprises the following steps: - provide the thermally insulating barrier (4; 5), which comprises a first insulating panel (10; 100) and a second insulating panel (10; 100) juxtaposed to the first insulating panel (10; 100), each having a top plate (17) defining a support surface (18) against which the sealing membrane rests, the top plates (17) of the first and second insulating panels (10) each having at least one groove (20), the grooves (20) of the first and second insulating panels (10;100) juxtaposed being aligned and extending along a longitudinal direction (x), each groove (20) opening at the level of the support surface (18) and having in the thickness of the thermally insulating barrier an entry zone (201) and a retention zone (202) disposed under the entry zone and which develops parallel to the support surface (18), a dimension of the retention zone (202) in a transverse direction being greater than a dimension of the entry zone (201) in the transverse direction; each groove (20) of the first and second juxtaposed insulating panels (10; 100) having, opposite the other among the first and second insulating panels (10; 100), a notched end (21), the dimension in the transverse direction of the entry zone (201) being widened at the notched end (21); the notched ends (21) of the two insulating panels (10;100) juxtaposed together forming an elongated recess (210) along the longitudinal direction (x); - provide a welding support (25) comprising a welding wing (251) and an anchoring wing (252) inclined relative to the welding wing; - slide the said welding support (25) into the groove (20) of the first insulating panel (10; 100) among the first and second insulating panels, up to a restraint state in which the anchor wing (252) is retained in the restraint zone (202) of said groove (20) of the first insulating panel (10; 100); - insert a positioning tool (30) into the elongated recess (210), the positioning tool comprising a first peripheral wall (33) and a second peripheral wall (33) spaced from the first peripheral wall in the transverse direction (y) by a flared channel (36) extending in the longitudinal direction (x), the flared channel opening on one side through an insertion orifice (410), and on the other side through a release orifice (420), the flared channel having a dimension in the transverse direction (y) decreasing from the insertion orifice to the release orifice, the flared channel being aligned with the groove (20) of the first insulating panel (10; 100), the insertion orifice (410) being opposite the groove of the first insulating panel;- slide the welding support (25) into the flared channel (36) from the insertion hole (410) to the release hole (420); - slide the welding support (25) into the groove (20) of the second insulating panel (10; 100); - place a strut (26) of the sealing membrane (12; 120) onto the support surface (18), the strut (26) being a profiled piece extending along the longitudinal direction (x) and having a cross-section comprising a flat central portion (261) resting on the support surface (18) and at least one raised lateral edge (262), connected to the flat central portion (261) and projecting from the support surface (18); - fix the raised lateral edge (262) of the strut (26), by welding, onto the welding flange (251) of the welding support (25).

2. Method of installing a sealing membrane (12; 120) according to claim 1, wherein the first peripheral wall (33) and the second peripheral wall (33) have an outer contour (34; 341, 342) corresponding in shape with a contour of the elongated recess (210).

3. A method for installing a sealing membrane (12; 120) according to claim 1 or claim 2, wherein the positioning tool (30) has a stop surface (40) bearing against the support surface (18) when the positioning tool is inserted into the elongated recess (210), in which at least one of the first and second peripheral walls (33) has, in a depth direction (z) perpendicular to the support surface, a dimension (H) less than a dimension (E), in the depth direction (z), of the inlet zone (201) between the support surface and the retention zone (202).

4. Method of installing a sealing membrane (12; 120) according to claim 3, wherein the first and second peripheral walls (33) each have, in the depth direction (z), a dimension less than one dimension, in the depth direction (z), of the inlet zone (201) between the support surface (18) and the retention zone (202).

5. A method for installing a waterproofing membrane (12; 120) according to any one of claims 1 to 4, wherein the thermally insulating barrier (4; 5) comprises a third insulating panel (10; 100), juxtaposed to the second insulating panel, which has an upper plate (17) defining together with the upper plates (17) of the first and second insulating panels (10; 100) the support surface (18) against which the waterproofing membrane (12; 120) rests, the upper plate of the third insulating panel having at least one groove (20), aligned with at least one groove of the second insulating panel and extending in the longitudinal direction (x), the groove of the third insulating panel opening at the level of the support surface (18) and having in the thickness of the thermally insulating barrier (4;5) an entry zone (201) and a retention zone (202) disposed below the entry zone and extending parallel to the support surface, one dimension, in the transverse direction (y), of the retention zone (202) being greater than one dimension, in the transverse direction (y), of the entry zone (201); each groove of the second insulating panel and the third insulating panel placed side by side having, opposite the third or second insulating panel, a notched end (21), the dimension in the transverse direction of the entry zone being enlarged at the notched end; the notched ends (21) of the second insulating panel and the third insulating panel placed side by side jointly forming a second elongated recess (210) in the longitudinal direction, the elongated recess jointly formed by the notched ends of the first and second insulating panels; juxtaposed insulating panels having a first elongated recess (210); wherein the process comprises the following steps, prior to the step of placing the edge of the sealing membrane (12; 120) on the support surface: - remove the positioning tool (30) from the first elongated recess (210); - insert the positioning tool (30) into the second elongated recess (210), the flared channel (36) being aligned with the groove (20) of the second insulating panel (10; 100), the insertion hole (410) being opposite the groove of the second insulating panel; - slide the welding support (20) into the flared channel (36) from the insertion hole towards the release hole, - slide the welding support into the groove of the third insulating panel.

6. A positioning tool, characterized in that it comprises a gripping portion (31) and an insertion portion (32) extending from the gripping portion, the insertion portion (32) comprising a first peripheral wall (33) and a second peripheral wall (33) separated from the first peripheral wall (33) by a flared channel (36) extending in a longitudinal direction (x), the flared channel opening on one side through an insertion orifice (410), and on the other side through a release orifice (420), the flared channel having a dimension in a transverse direction (y) that is perpendicular to the longitudinal direction (x), decreasing from the insertion orifice to the release orifice, in which the gripping portion (31) connects the first peripheral wall (33) and the second peripheral wall (33), the gripping portion being configured to serve as a grasping means for an operator.

7. Positioning tool according to claim 6, wherein the positioning tool (30) has a U-shaped section in a plane normal to the longitudinal direction, the flared channel (36) being open on one side opposite the gripping portion (31), between the insertion orifice (410) and the release orifice (420).

8. Positioning tool according to claim 6 or claim 7, wherein the positioning tool (30) comprises a first stop surface (40) extending in a stop plane (P) defined by the longitudinal direction (x) and the transverse direction (y), the first peripheral wall (33) projecting from the first abutment surface in a depth direction (z) perpendicular to the abutment plane (P).

9. Positioning tool according to claim 8, wherein the positioning tool (30) comprises a second stop surface (40) extending in the stop plane (P), the second peripheral wall (33) projecting from the second stop surface in the depth direction (z).

10. Positioning tool according to claim 8 or claim 9, wherein a first height (H) is defined in the depth direction (z) between the first stop surface (40) and a distal end (39) of the first peripheral wall (33) opposite the first stop surface, a second height (H) is defined in the depth direction (z) between the first stop surface (40) and a distal end (39) of the second peripheral wall (33) opposite the first stop surface, and wherein the first height (H) is equal to the second height (H).

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