FR2977575A1 - COUPLER FOR MAINTAINING AN ELEMENT IN RELATION TO A RETENTION STRUCTURE - Google Patents

Abstract

Coupler for holding relative to a retaining structure (3) an element (1) subjected to decohesion stresses; it comprises: a foot (15), whose outer casing (15a) encloses an insulating plug (15d) and an elastic means (15b), which pushes said plug against the retaining structure; a head (16) whose outer casing (19) encloses an insulating ring (20) and a sleeve (21) whose two ends are threaded internally; the sleeve (21) receives a tip (24) equipped with a collar (24a), which bears on a plate (25) carried by the element, the housing is secured to a plate (18) mechanically connected to the element (1); and finally a rod (14) threaded at both ends and screwed on one side in the ring (20) of the head and the other in a nut (15c) of the foot.

Description

The present invention relates to a sealed and thermally insulating tank integrated into a load-bearing structure, in particular in the double hull of a vessel intended for the transport of liquefied natural gas. In the state of the art, numerous embodiments of this type of vessel have already been described. Generally, it is expected that the tank comprises a primary barrier in contact with the liquid contained in the tank and a secondary barrier disposed between the primary barrier and the carrier structure formed by the double hull of the ship; each of these barriers comprises a thermally insulating layer covered with metal sheets which seal, the sealing sheets covering the insulating layer on the side of the inside of the tank. In a particular embodiment, the sealing barriers constituted by the aforementioned metal sheets have corrugations in two orthogonal directions.

In French Patent 1492959, this type of tank has already been described, specifying that the corrugations of the primary sealing barrier are preferably all protruding on the side of the inside of the tank. On the other hand, the corrugations of the secondary sealing barrier are raised towards the outside of the tank and the secondary insulation barrier comprises grooves for accommodating said undulations. The fact of having protruding corrugations on the primary sealing barrier can present a certain number of drawbacks: in the first place, the sheet constituting the primary sealing barrier can be deformed under the action of the oscillations of the liquid transported in Because of the presence of embossed relief in second place, the reliefs cause difficulties in setting up the welding apparatus used to ensure the continuity of the seal.

In the Korean patent application 10-2009-0009284, it has been proposed to produce, for a tank of this type, a primary sealing barrier comprising reentrant corrugations, that is to say turned towards the outside of the tank; these corrugations are housed in grooves provided in the primary insulating barrier. The establishment of the secondary sealing barrier imposes, because of the constitution of the grooves by bringing two adjacent primary insulation blocks together, to use a secondary sealing barrier constituted by a composite sheet "triplex" so that one can not benefit, for the secondary sealing barrier, the elasticity that allows to have a network of corrugations. It is also known, for example from FR-A-2798902 or FR-A-2877639, insulating and sealed tanks in which the two sealing barriers are made with invar strakes with raised edges which are welded edge to edge on both sides of parallel welding supports. These welding supports are each housed in grooves of the cover plates of parallelepipedic boxes forming the underlying insulating barrier, so as to retain the sealed metal membrane on these boxes.

According to one embodiment, the present invention therefore has for its first object, a sealed and thermally insulating tank placed in a carrying structure, comprising: a secondary thermal insulation comprising a plurality of secondary insulation blocks juxtaposed on the support structure, a seal secondary body having a plurality of sealed secondary metal plates disposed on the secondary insulating blocks and welded to each other, a primary thermal insulation comprising a plurality of primary insulating blocks juxtaposed on the secondary seal, a primary seal comprising a plurality of primary metal plates seals arranged on the primary insulative blocks and welded to each other, secondary mechanical coupling members extending through the secondary thermal insulation at the edges of the secondary insulating blocks and maintaining the secondary insulating blocks in the ap on the supporting structure, and

primary mechanical coupling members extending through the primary thermal insulation at the edges of the primary insulating blocks and maintaining the primary insulating blocks bearing on the secondary seal, characterized in that the primary metal plates, and respectively secondary, are arranged so that the edges of the metal plates are offset relative to the edges of the primary and secondary insulation blocks underlying the primary metal plates, and secondary respectively, are held in abutment on the primary insulating blocks, and respectively secondary, only by the primary and secondary mechanical coupling members, and that the primary and secondary mechanical coupling members are respectively attached to the primary and secondary metal plates at the remote attachment points of the edges of metal plates es primary, and respectively secondary. According to particular embodiments, such a vessel may have one or more of the following characteristics. According to one embodiment, the primary and secondary metal plates have a contour shape identical to the contour shape of the primary and secondary secondary insulation blocks. For example, this shape of contour can be each time rectangular, square, hexagonal or other shape to achieve a tiling plan. According to one embodiment, the primary and respectively secondary metal plates consist of thin metal sheets shaped so as to have, in two orthogonal directions, corrugations projecting in relief towards the carrier structure, the primary insulating blocks, respectively secondary, having grooves for accommodating said undulations.

According to one embodiment, the corrugations of a primary metal plate, and respectively secondary, are equidistant in each of their two directions. According to one embodiment, the distances between two successive corrugations of the two corrugation directions of a primary metal plate, and respectively secondary, are equal, so as to delimit on the two seals inter-corrugation areas of square shape viewed perpendicularly. to the supporting structure. According to one embodiment, a primary, and respectively secondary, mechanical coupling member is supported on the primary, and respectively secondary, sealing in a plane area between the orthogonal corrugations of said seal. According to one embodiment, the grooves which receive the corrugations of the primary and secondary sealed plates have a U- or V-shaped cross-section, the opening of the groove being adapted to the shape of the cross-section of the corrugations. According to one embodiment, the cross section of the grooves is a V, whose branches form between them an angle greater than or equal to 90 °. According to one embodiment, a groove of a primary and respectively secondary insulating block is delimited each time by shims introduced into a groove wider than the groove, the shims leaving channels in said groove between the block. primary insulation, and respectively secondary, and the corrugation of a primary waterproof plate, and respectively secondary, housed in said groove, to allow a gas sweep, for example nitrogen. According to one embodiment, a primary, and respectively secondary, mechanical coupling member comprises a plate distributing the forces on the primary and, respectively, secondary sealing barrier, and a means of primary and secondary stress transmission linked to said platen, the force transmission means of the secondary mechanical coupling member being connected to the carrier structure. According to one embodiment, the force transmission means of the primary mechanical coupling member is connected to a secondary mechanical coupling member coaxial with the primary mechanical coupling member. According to an alternative embodiment, the force transmission means of the primary mechanical coupling member is connected to a secondary insulating block remote from the edges of the secondary insulating block, the secondary mechanical coupling members associated with said secondary insulating block being offset from said primary mechanical coupling member.

According to one embodiment, the primary and secondary insulation blocks comprise notches formed on two opposite edges of said primary and secondary insulation blocks, the notches formed in two primary and adjacent secondary insulation blocks being each time aligned to define a housing capable of passing a primary, and respectively secondary, mechanical coupling member According to one embodiment, the primary and secondary insulation blocks 35 have cut edges at the corners of said primary insulating blocks, respectively secondary, the cut edges of four primary and secondary insulation blocks, adjacent at a corner each defining a housing adapted to pass a primary mechanical coupling member, and respectively secondary. According to one embodiment, a primary and secondary insulation block consists of an insulating foam layer bordered on its two large faces by a plywood plate. Such a tank can be part of a land storage facility, for example to store LNG or be installed in a floating structure, coastal or deep water, including a LNG tank, a floating storage and regasification unit (FSRU) , a floating production and remote storage unit (FPSO) and others. According to one embodiment, a vessel for the transport of a cold liquid product comprises a double hull and a aforementioned tank disposed in the double hull.

According to one embodiment, the invention also provides a method of loading or unloading such a vessel, in which a cold liquid product is conveyed through isolated pipes from or to a floating or land storage facility to or from the vessel vessel. According to one embodiment, the invention also provides a transfer system for a cold liquid product, the system comprising the abovementioned vessel, insulated pipes arranged to connect the vessel installed in the hull of the vessel to a floating storage facility. or terrestrial and a pump for driving a flow of cold liquid product through the insulated pipelines from or to the floating or land storage facility to or from the vessel vessel.

The second subject of the present invention is a coupler for maintaining, with respect to a retaining structure, an element subjected to forces likely to cause its decohesion with respect to the structure, said element being delimited by two parallel rigid walls, the first being wall being closer to the retaining structure and the second being further away, characterized in that it comprises: a first part which forms the foot of the coupler and comprises an outer casing, said outer casing being fixed on the structure, said housing enclosing a plug of thermally insulating material and an elastic means, which push said plug against the retaining structure by means of a nut; a second part, which forms the head of the coupler and comprises an outer casing secured to the element, said outer casing enclosing a thermally insulating ring and a substantially cylindrical sleeve internally threaded at its two ends, the thread farthest from the structure retainer receiving a nozzle equipped with a flange, which bears on a plate carried by the second wall of the element, the housing being secured to a peripheral plate placed in a recess between said plate and the second wall of the element; and finally a first threaded rod at its two ends and screwed on one side into the sleeve of the coupler head and on the other, into the nut of the foot of said coupler, the screwing of said first rod ensuring the maintenance of the element against the retaining structure. It can be provided that the element held with respect to the retaining structure, is associated with a complementary element covered with a metal plate on the opposite side to the retaining structure and that the thread of the sleeve, which is not occupied by the first rod, receives the threaded end of a second rod, which provides the connection between the sleeve and a connection secured to the complementary element, said 7 s connection comprising, in a complementary housing of the same structure as that of the head of the coupler, on the one hand, a resilient means interposed between a rim of the second rod and the complementary casing and, on the other hand, a threaded sleeve whose collar makes it possible, by welding on the metal plate, to seal between the outer space and the interior of the complementary element. In a preferred embodiment, the nut of the coupler foot externally has a square shape whose angles rub on the housing or on a part connected thereto. The plates of the casings and / or complementary housing of the coupler may have a quadrangular shape. Advantageously, the second rod of the coupler has at least a portion of smaller section than the first rod.

According to a preferred use of the coupler according to the invention, the supporting structure is the double hull of a ship and the element subjected to decohesion stresses is a sealed and thermally insulating barrier element of a tank integrated in the ship. It can be provided that the coupler is associated with a complementary element, which is a primary barrier element, the element closest to the supporting structure being a secondary barrier element. Advantageously, the threaded sleeve of the complementary housing receives, on the farthest side of the support structure, the threaded end of a means forming a relief relative to the metal plate, which covers the complementary element. The first wall of the element associated with the coupler can bear against the supporting structure with interposition of smoothing wedges. The plate associated with that of the walls of the element and / or of the complementary element, which is furthest from the retaining structure, is a thin metal plate formed by welding identical sections; in a first variant, the plate sections are welded clinch and comprise corrugations according to two orthogonal directions. In another variant, the plate sections are welded with raised edges. The third subject of the present invention is an apparatus for pressing two metal sheets onto a plane support in order to maintain their relative positions for a welding operation on their free edges, characterized in that the right of the one of the sheets is positioned a support member disposed at a distance from the edges to be welded and carrying a pivot point at a fixed distance above the sheets to be welded, the pivot point of this support member being used as a pivot for a lever, one end of which is equipped with a pressure pad positioned at the edges of the weld, the lever being subjected, in addition, to the action of an actuator placed on one of the welding plates, the actuator being able to push the buffer on the edges to be welded to press the two sheets against each other in the vicinity of the weld site. In a preferred embodiment, the actuator is an inflatable flexible hose, which is interposed between the lever and an area of one of the sheets to be welded, which is remote from the weld site; it is preferred that the pivot of the lever is further away from the actuator than the pressure pad. In a particularly advantageous application, the sheets to be welded are sheets having rectilinear corrugations, in particular parallel to the edges to be welded, each corrugation being positioned in a groove of the plane support; the grooves may have a cross section in the form of a V or a U and, advantageously, the branches of the V of a groove have an angular aperture of about 90 °. The support member may be disposed in the area between the pressure pad and the groove closest to said buffer. In a preferred application, the plane support is a wall of a thermally insulating barrier element of a sealed and thermally insulating tank integrated into a carrier structure of the vessel and the welding plates constitute, after welding, a sealing barrier. said tank, the support member associated with the lever being provided by a mechanical coupling member, which ensures the cohesion of the thermally insulating barrier elements with the carrying structure of the tank; the support member associated with the lever is a raised means screwed into a sleeve or threaded end integral with a mechanical coupling member, said relief means being equipped with a peripheral collar, which is supported on the plates to solder to clin.

Some aspects of the invention consist in using as a sealing barrier, both primary and secondary, sheets having a network of corrugations directed towards the outside of the tank for the two barriers. The advantage of such an arrangement is that it is possible for the two barriers to benefit from the elasticity provided by the undulation networks and to eliminate the disadvantages due to the presence, the primary sealing barrier, ripples projecting towards the inside of the tank.

To better understand the object of the invention will now be described, by way of purely illustrative and non-limiting examples, several embodiments shown in the accompanying drawing. In this drawing: FIG 1 shows, in plan, the relative positioning of a sealed barrier unit and an insulating barrier unit for a first embodiment of the invention; FIG. 1A partially shows, in plan view, a sealed and insulating tank wall 30 comprising an assembly of sealed barrier units and underlying insulating barrier units, the insulating barrier being covered by the sealed barrier on only part of its surface; FIG. 2 represents a vessel wall according to a first embodiment, seen in section along the line II - II of FIG. 1; FIG. 3 represents an embodiment variant of the grooves 5 in which the corrugations of the primary and secondary sealing barriers are put in place; FIG. 4 represents, in section perpendicular to the supporting structure, the constitution of a secondary coupler retaining a sealed and insulating tank wall to ensure its cohesion with the carrying structure, the tank wall being able to be, in this figure, equipped with a single thermal insulation barrier and a single sealing barrier; FIG. 5 shows in section perpendicular to the carrier structure, a primary coupler intended to ensure the cohesion between a primary barrier and an underlying secondary barrier, itself retained on the bearing structure by a secondary coupler such as that represented in Figure 4, the two couplers being coaxial; - Figure 6 shows in detail the foot of the secondary coupler 20 of Figure 4, seen in the axis of its rod, in a section perpendicular to said axis made at the level of the nut prisoner; FIG. 7 represents, in plan view, a section of the head of a primary or secondary coupler according to FIGS. 4 and 5, made at the level of the platen set up below the primary sealing barrier; secondary; FIG. 8 is a view similar to FIG. 2 showing a vessel wall according to a second embodiment, the secondary barrier being retained against the carrying structure 30 by secondary couplers and the primary barrier being retained on the secondary barrier by means of primary couplers, the two types of couplers being staggered in both groove directions in the primary and secondary insulation units; FIG. 9 represents, in perspective, a unit of the primary insulation barrier and a unit of the secondary insulation barrier of the wall of FIG. 8, the arrows showing the positioning of the primary and secondary couplers; FIG. 10 shows in detail the base, which allows the foot of a primary coupler to be tied down, in the embodiment of FIGS. 8 and 9; FIG. 11 represents the positioning of a relief member in relief on the primary sealing barrier, in line with a coupling member of the primary barrier, at the junction of two adjacent elements of the primary insulating barrier, this view being a partial section made perpendicularly to the carrier structure and the average line of a corrugation of the primary sealing barrier; FIG. 12 represents, in a section similar to that of FIG. 11, the use of a support member for an apparatus intended to press one against the other the edges of two sheets of sealing barrier primary that is desired to weld clincher to ensure tightness; FIG. 13 is a cutaway schematic representation of a vessel of a LNG carrier and a loading / unloading terminal of this vessel.

Referring to FIGS. 1 to 3, it can be seen that 1, as a whole, has designated a secondary insulating barrier formed of juxtaposed modular blocks and 2, as a whole, a primary insulating barrier formed of juxtaposed modular blocks. . In the embodiment shown, these modular blocks are parallelepipedic pavers, namely secondary insulating pavers 28 and primary insulating pavers 29, but other geometries are also possible. Each of these secondary insulating blocks 28, respectively primary 29, consists of a thermally insulating foam board 1a, respectively 2a, of generally quadrangular shape; each panel 1a, respectively 2a is covered, on its large faces, a plywood base plate 1b, respectively 213, and a plywood cover plate 1c, respectively 2c. The bottom plate 1b of the secondary insulating blocks 28 bears against the carrier structure 3 of a ship by means of soft mastic pads 4. The cover plates 1c and 2c comprise grooves 5 having a quadrangular cross-section, said grooves penetrating to the foam layers 1a and 2a. Flat areas 46 are delimited between these grooves 5. Each of the insulating barriers, secondary 1 and primary 2 respectively, bears on its wall farthest from the supporting structure 3, a sheet of metal, for example stainless steel, which constitutes a secondary, respectively secondary, secondary and secondary barrier 7. Each of the secondary, and respectively primary, secondary sealing barriers 7 is in the form of an assembly of rectangular, secondary and primary metal plates 25a, which comprise each time undulations 8 having a V-shaped profile, the two branches of the V having an angular aperture of about 90 °. It is also possible to make an opening greater than 90 °, a lower opening being discouraged because of the welding difficulties that result. The corrugations 8 of each secondary metal plate 25 and 25a respectively primary are made in two orthogonal directions, at equal distances, so that the network of corrugations defines planar interverteplane areas 40 of square shape (views perpendicular to the structure carrier 3), as is clearly visible in FIGS. 1 and 1A for the secondary barrier. The primary barrier can be realized identically.

The secondary 25 and primary 25a metal plates are arranged on the secondary insulating blocks 28 and 29, respectively, so that the corrugations 8 are in each case housed in the grooves 5 of the underlying insulating blocks, whereas the planar areas 40 s 1 is a preferred embodiment of the grooves 5 containing the corrugations 8 of the sealing barriers 6 or 7. In this variant, the branches of the V, which constitute the cross section of the corrugation 8, are supported by wedges 9, which, at their upper part and at the fold of the V, leave free zones, which constitute channels 10 in which it is possible to circulate nitrogen, between the secondary or primary 6 or primary watertight barrier 7 and secondary insulating pavers 28 or primary 29. These channels constitute an interesting device for the safety in case of leakage. But, in addition, the fact of supporting the branches of the V of the corrugation 8, improves the mechanical strength of the corrugations. Relaxation slots may be provided below the grooves 5. The maintenance of the secondary insulating pavers 28 and primary 29 on the carrier structure 3 constituted by the double hull of the vessel where the tank is installed, is provided by means of coupling members mechanical, whose position is always on the periphery of insulating pavers 28 and 29 to maintain. Figures 1 and 1a show the relative arrangement of the secondary insulating barrier 1 and the secondary sealed barrier 6 according to one embodiment. The secondary coupling members appear in plan by their upper ends 11. A secondary metal plate 25 is of equal size to a secondary insulating pad 28 and is disposed offset by half a length and half a width with respect to secondary insulating blocks 28 which support it. Thus, the coupling members 11 located on the edges of the secondary insulating pavers 28 are positioned at the center of the square inter-corrugation zones 40 of the secondary metal plate 25. The lines 35 designate overlapping zones of the adjacent secondary metal plates. The relative arrangement of the primary insulating barrier 2 and the primary watertight barrier 7 may be identical. The gap between the edges of the insulating pavers and the edges of the metal plates they support has several advantages. On the one hand, the sealing between the edges of the adjacent metal plates is simpler when these edges are regular, which would not be the case if it were also necessary to arrange attachment points of the couplers at the edges of the metal plates. . On the other hand, the areas between the adjacent insulating blocks, where the couplers are arranged, are likely to have slight level offsets, due to the set of mounting of each insulating pad. These zones are therefore likely to offer a less uniform support surface for the metal waterproofing membrane than the central zones of the insulating pavers, hence a possible concentration of stresses in these zones located between the insulating pavers. In the proposed arrangement, the most fragile areas of the waterproofing membrane, namely the edges of the metal plates, are disposed on the areas where the support surface is the most uniform, while the areas between the insulating pavers are covered by the central portion of the metal plates 25 or 25a, which is more resistant to stress, in particular due to the elasticity imparted by the corrugations 8. A first embodiment of the vessel wall will now be described. Figure 2 provides an overall representation of this first embodiment, and Figures 4 and 5 provide a detailed representation of the mechanical coupling members.

As is clearly visible in FIG. 2, the coupling members here comprise coaxial secondary couplers 41 and primary couplers 42: the primary coupler 42, which passes through the primary insulating barrier 2, is arranged along the same axis as the secondary coupler 41, which crosses the secondary insulating barrier 1. Each time, the passages of the secondary couplers 41, respectively primary 42, through the secondary insulating barrier 1, respectively primary 2, is constituted by notches 12 formed at the edge of the secondary insulating pavers 28, respectively primary 29, and by corner notches 13 made at the corners of the secondary insulating pavers 28, respectively primary 29. The complete housing of a secondary coupler 41, respectively primary 42, consists of two notches 12 made in two insulating pavers adjacent or by the four notches 13 of four adjacent insulating pavers. As previously indicated, the coupling system of the primary and secondary insulating barriers 1 and 2 with respect to the carrier structure 3 consists of two types of couplers 41 and 42. An embodiment of a secondary coupler 41 is shown. in Figure 4. This secondary coupler which serves to maintain the secondary insulating barrier 1 against the carrier structure 3 could be used for embodiments in which the insulation of the tank is obtained with a single insulating barrier. The coupler 41 consists of a rod 14, which connects a coupler foot 15 welded to the carrier structure 3 and a coupler head 16 secured to the cover plate 1c of a secondary insulating pad 28. The coupler foot 15 comprises a housing 15a welded to the supporting structure 3. The housing 15a is substantially cylindrical and contains a stack of Belleville washers 15b and a nut 15c screwed onto the rod 14. The nut 15c has a square shape and the angles of the nut come rub on the housing 15a so as to prohibit the rotation of the nut 15c. The bottom plate 1b of the secondary insulating pad 28 rests on a smoothing wedge 17. The smoothing wedge 17 ensures the flatness of the support and makes it possible to partially dismantle the insulation. The cover plate 1c of the secondary insulating block 28 comprises a recess for the passage of a cylindrical casing 19, which externally delimits the head 16. This casing 19 is constituted by a cylindrical punch formed in the center of a square fixing plate 18 The cylindrical casing 19 contains a heat insulating ring 20, fitted around the end of a sleeve 21. The sleeve 21 comprises at each of its two ends a threaded bore: in one of these bores is put in place the threaded ends of the rod 14, which does not cooperate with the nut 15c. The plate 18 is positioned in a counterbore 22 of the cover plate 1c and is covered by the secondary sealing barrier 6. A flanged edge 37 of the cylindrical casing 19 prevents any movement of the plate 18 and thus transmits the forces of tearing supported by the secondary insulating pad 28 to the support structure 3 via the rod 14. The elastic clearance obtained thanks to the Belleville washers 15b compensates for thermal contractions and possible dynamic deformations of the hull. Having provided a threaded bore on the side of the sleeve 21 opposite the rod 14, allows the introduction in this bore of the threaded portion 23, a male end 24, having a flange 24a. The threaded portion 23 is engaged through a bore of the secondary metal plate 25 to be screwed into the sleeve 21. Thus, the male end 24 constitutes a point of attachment which keeps the secondary metal plate 25 against the plate of cover 1c. The collar 24a makes it possible to produce a sealed weld on the secondary metal plate 25 around said bore to restore the seal at this point of attachment. This male end piece 24 can be used for placing scaffolds or mounting tools in the tank, or an apparatus for pressing the sheets constituting the sealing barriers when they are joined by a weld. at a glance.

FIG. 5 shows the implementation of the secondary coupler 41, which has just been described, for coaxially fixing a primary coupler 42 such as that represented in FIG. 2. The left part of FIG. 5 corresponds to the head 16 of the secondary coupler 41 shown in detail in Figure 4, except that the male end 24 has been replaced by a female end 26 having a threaded bore on the farthest side of the carrier structure 3. This endpiece 26 also comprises a peripheral flange 26a that can be welded to the secondary metal plate 25, which constitutes the secondary sealing barrier 6. It receives, in its threaded bore, the threaded end of a rod 27 similar to the rod 14 The threaded portion of the rod 27, which fits into the tip 26, has the same diameter as the rod 14, but the residual length of the rod 27 has a smaller diameter so as to allow a break in the zone of connection of the two diameters if the forces exerted on the coupling members are greater than a tolerable limit. The rod 27 passes through the primary insulating barrier 2 to arrive in a connection 30, which provides the connection between the rod 27 and the cover plates 2c of two or four primary insulating blocks 29. This connector 30 comprises a housing 30a quite similar to the cylindrical casing 19 of the head of the secondary coupler 41 of FIG. 4. The casing 30 is a cylindrical stamp obtained in the central zone of a plate 18 identical to that of FIG. 4 and positioned in the same way under the metal plate primary 25a. The plate 18 is quadrangular. Inside this housing 30a are disposed Belleville washers 30b and a flange 30c of the rod 27 resting on Belleville washers 30b. In the casing 30a, there is positioned a threaded sleeve 31 comprising, along its axis, an external thread referred in the cylindrical housing 30a, and a threaded hole 38 turned towards the inside of the vessel, which allows the possible fixing of a relief means of the same type as the male end 24 shown in Figure 4, not shown in Figure 5. The threaded sleeve 31 comprises a peripheral flange 31a, which can be welded to a primary metal plate 25a. The coupling members, which have just been described, allow a slight relative rotation of the various elements assembled. The support of the flange 24a, respectively 31a, on the secondary metal plate 25, respectively primary 25a, makes it possible to maintain the secondary watertight barrier 1, respectively primary 2, bearing on the cover plates 1c, respectively 2c, of the insulating blocks secondary 28, respectively primary 29. With a sufficient density of the primary and secondary couplers, no further attachment is necessary to maintain the sealed membranes on the walls of the tank. The edges of the walls and the connections between the watertight barriers at the angles between two walls of the tank can be made by welding the sealed metal plates on corner angles, according to the known technique. FIGS. 8 to 10 show a second embodiment of a tank wall, in which the coupling, which holds the primary and secondary insulating barriers 1 and 2 against the carrier structure 3, is formed by primary and secondary couplers 33 and 32, which are not aligned in their part where they pass through the primary and secondary insulating barriers 1. In this embodiment, the primary insulating pavers 29 and secondary 28 are identical to those corresponding to Figures 1 and 1A, but they are arranged differently. Instead of having a primary insulating pad 29 directly above a secondary insulating pad 28, it is intended here to offset the primary insulating pad 29 with respect to the secondary pad 29 from a certain distance in the insulating pad. two directions of the plane of the tank wall. The lateral offset distance 61 is less than half the width of the blocks in the example shown in FIGS. 8 and 9. The longitudinal offset distance 62 is equal to the longitudinal distance between two corrugations 8 in the example shown in FIG. FIG. 9. Under these conditions, the primary 33 and secondary 32 couplers are no longer in alignment with one another as is clearly visible in FIG. 9, where the positions of the primary couplers 33 are represented by the arrows P1, P2 and P3 and the positions of the secondary couplers 32 are represented by the arrows 51 ,. S2 and S3. All the couplers have not been shown in FIG. 9. It is possible to use typically eight couplers per insulating block, depending on the dimensions of the insulating blocks. In this embodiment, the secondary coupler 32 consists of a rod 32a, which, at one of its ends, is connected to the supporting structure 3 and at its other end, is connected to the lid wall of the Secondary insulators 28. The aforementioned connections can be made identically to the first embodiment. The primary coupler 33 comprises a rod 33a, which, at one of its ends, is connected to the lid wall 2c of two or four primary insulating blocks 29 and at its other end is connected to the cover wall 1c of a secondary insulating pad 28 remote from the edges thereof. The connection of this rod 33a with the lid walls 2c is performed with a device corresponding exactly to that illustrated on the right part of Figure 5 and previously described. The connection of the rod 33a with the lid wall 1.c is effected by the cooperation of a thread of the rod 33a with a base 34 shown in FIG. 10. At the crossing of the secondary sealing barrier 6, the rod 33a has a flange 33b which is welded to the secondary metal plate 25 constituting the secondary sealing barrier. In this embodiment, the shifting of the primary 33 and secondary 32 couplers makes it possible to limit the thermal bridges between the inside of the vessel and the carrier structure 3. Moreover, an offset is maintained each time between the secondary metal plates 25, respectively 25a, and the secondary insulating pads 28, respectively primary 29, which support them, in the same way as in the first embodiment. This gives an arrangement of the tank wall in which the four successive layers forming the tank wall have a respective offset tiling. In other words, each of the following four elements is positioned offset from the other three in the two directions of the plane: the secondary insulating pad 28, the secondary metal plate 25, the primary insulating pad 29 and the primary metal plate 25a. FIG. 11 shows in section a primary or secondary sealed barrier equipped with a male end-piece 24 such as that previously described and shown in FIG. 4. The elements already described and which are found in the embodiment of FIGS. and 12 have been designated in these new figures by the same references as in Figures 1 to 10 and their description has not been repeated in detail. To facilitate the continuation of this description, it will be assumed that FIG. 11 represents a secondary barrier but the situation would be identical if it were a primary barrier. Adjacent zone of two secondary insulating pavers 28 are seen with their plywood cover plates 1c. As illustrated in Figures 1 and 1A, coupling members (not visible in Figure 11) are disposed in the plane 51 located between two adjacent insulating pavers 28. The secondary sealing barrier 6 is constituted by the assembly of the sheet metal plates 25, this assembly being done by a seam weld 52 of two adjacent plate plates. FIG. 12 represents an apparatus placed on the wall area described above and shown in FIG. 11.

The male end 24 constitutes here a pivot point 53 for a lever 54 which carries, at one of its ends, a pressure pad 55 and, at its other end, an actuator consisting of an inflatable flexible hose 56. The lever 54 comprises a bore in which is engaged the threaded rod 43 of the male end 24 with sufficient clearance to allow some angular movement of the lever 54. A nut 44 maintains this commitment. The pivot point 53 is closer to the pressure pad 55 than to the inflatable hose 56 to multiply the force generated by the hose 56 and to have a high pressure at the pad 55. The dimensions of the lever are such that the distance 53 -55 measured parallel to the metal sheets 25 is equal to the distance between the plane 51 and the axis along which the weld 52 has to be made. It can be seen that, in this way, the pressure pad 55 is applied to the site of the clutch weld 52, which makes it possible to press the two weld plates 25 against each other at the site of the weld. without having to pre-score. The techniques described above for making a tank wall can be used in different types of tanks, an LNG tank in a land installation or in a floating structure such as a LNG tank or other. Referring to Figure 13, a broken view of a LNG tank 70 shows a sealed and insulated tank 71 of generally prismatic shape mounted in the double hull 72 of the ship. The wall of the tank 71 comprises a primary sealed barrier intended to be in contact with the LNG contained in the tank, a secondary sealed barrier arranged between the primary sealed barrier and the double hull 72 of the ship, and two insulating barriers arranged respectively between the primary watertight barrier and the secondary watertight barrier and between the secondary watertight barrier and the double hull 72. In a manner known per se, loading / unloading pipes 73 arranged on the upper deck of the ship may be connected, by means of appropriate connectors, at a marine or port terminal for transferring an LNG cargo from or to the tank 71. Figure 13 shows an example of a marine terminal including a loading and unloading station 75, an underwater pipe 76 and an onshore installation 77 The loading and unloading station 75 is a fixed off-shore installation comprising a movable arm 74 and a tower 78 which supports the movable arm 74. The movable arm 74 carries a bundle of insulated flexible pipes 79 which can be connected to the loading / unloading pipes 73. The movable arm 74 can be adapted to all the LNG carriers . A connection pipe (not shown) extends inside the tower 78. The loading and unloading station 75 enables the loading and unloading of the LNG tank 70 from or to the shore facility 77. liquefied gas storage tanks 80 and connecting lines 81 connected by the underwater line 76 to the loading or unloading station 75. The underwater line 76 allows the transfer of the liquefied gas between the loading or unloading station 75 and the onshore installation 77 over a large distance, for example 5 km, which makes it possible to keep the tanker vessel 70 at great distance from the coast during the loading and unloading operations. In order to generate the pressure necessary for the transfer of the liquefied gas, pumps on board the ship 70 and / or pumps equipping the shore installation 77 and / or pumps equipping the loading and unloading station 75 are used.

Although the invention has been described in connection with several particular embodiments, it is obvious that it is not limited thereto and that it comprises all the technical equivalents of the means described and their combinations if they are within the scope of the invention. The use of the verb "to include", "to understand" or "to include" and its conjugated forms does not exclude the presence of other elements or steps other than those set out in a claim. The use of the indefinite article "a" or "an" for an element or a step does not exclude, unless otherwise stated, the presence of a plurality of such elements or steps. In the claims, any reference sign between parentheses can not be interpreted as a limitation of the claim.

Claims (12)

REVENDICATIONS1. Coupler for maintaining with respect to a retaining structure (3) an element (1, 2) subjected to forces that may cause its decohesion with respect to said structure, said element being delimited by two parallel rigid walls (1c, 1b, 2c, 2b), the first wall (1b, 2b) being closer to the retaining structure (3) and the second wall (1c, 2c) being further away, characterized in that it comprises: a first part, which forms the foot (15) of the coupler and comprises an outer casing (15a), said outer casing being fixed on the retaining structure (3), said casing enclosing a cap (15d) of thermally insulating material and an elastic means, which pushing said plug against the retaining structure by means of a nut (15c); a second part, which forms the head of the coupler and has an outer casing integral with the element, said outer casing enclosing a thermally insulating ring and a substantially cylindrical sleeve internally threaded to its two ends, the thread farthest from the retaining structure (3) receiving a nozzle (24, 26) equipped with a flange (24a, 26a), which bears on a plate (25) carried by the second wall of the element, the housing (19) being integral with a peripheral plate (18) placed in a countersink between said plate (25) and the second wall of the element; and finally a rod (4) threaded at its two ends and screwed on one side into the sleeve (21) of the coupler head (16) and on the other side into the nut (15c) of the foot (15). ) of said coupler, the screwing of said first rod (14) ensuring the maintenance of the element against the retaining structure (3). 2. Coupler according to claim 1, characterized in that the element (1) maintained relative to the retaining structure (3) is associated with a complementary element (2) covered with a metal plate (25a) on the opposite side to the retaining structure (3) and that the thread of the sleeve (21), which is not occupied by the first rod (14), receives the threaded end of a second rod (27), which provides the connection between the sleeve (21) and a connection (30) integral with the complementary element (2), said coupling (30) comprising, in a complementary housing (30a) of the same structure as that of the head (16), on the one hand, an elastic means (30b) interposed between a flange (30c) of the second rod (27) and the complementary casing (30a) and, on the other hand, a threaded sleeve (31), a flange (31a) of which by welding on the metal plate (25a), sealing between the outer space and the interior of the complementary element. 3. Coupler according to one of claims 1 to 2, characterized in that the nut (15c) of the foot (15) externally has a square shape whose angles rub on the housing (15a) or a part connected thereto . 4. Coupler according to one of claims 1 to 3, characterized in that the plates (18) of the housing (19) and the complementary housing (30a) of the coupler have a quadrangular shape. 5. Coupler according to one of claims 1 to 4, characterized in that the second rod (27) has at leasta portion of smaller section than the first rod (14). 6. Coupler according to one of claims 1 to 5, characterized in that the carrier structure (3) is the double hull of a ship and the element subjected to decohesion forces is a member (1,2) of waterproof and thermally insulating barrier of a vessel integrated in the vessel. Coupler according to Claim 1, characterized in that the complementary element with which it is associated is a primary barrier element (2), the element which is closest to the supporting structure (3) being a barrier element. secondary (1). 8. Coupler according to claims 2, 6 and 8 taken simultaneously, characterized in that the threaded sleeve (31) receives, on the farthest side of the carrier structure (3), the threaded end of a means forming a relief ( 24) relative to the metal plate (25a), which covers the complementary element (2). 9. Coupler according to one of claims 6 to 8, characterized in that the first wall (1b) of the element associated with the coupler bears against the supporting structure with the interposition of smoothing wedges (17). 10. Coupler according to one of claims 1 to 9, characterized in that the plate (25,25a) associated with that of the walls of the element and / or the complementary element, which is furthest from the structure retainer (3) is a thin metal plate formed by welding identical sections. 11. Coupler according to claim 10, characterized in that the plate sections are clinch welded andcomprises corrugations (8) in two orthogonal directions. 12. Coupler according to claim 10, characterized in that the plate sections are welded with raised edges.