EP2729729B1 - Thermally-insulating sealed tank - Google Patents

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 the French patent 1492959 this type of tank has already been described, specifying that the corrugations of the primary sealing barrier are preferably all protruding towards 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 raised undulations; secondly, the reliefs cause difficulties in setting up welding equipment used to ensure the continuity of the seal.

In the Korean patent application KR2010-0090036 it has been proposed to produce, for a tank of this type, a primary sealing barrier comprising reentrant undulations, 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.

We also know, for example according to 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 either side 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. We also know the document US 2006/117566 which discloses an LNG tank.

• une isolation thermique secondaire comportant une pluralité de blocs isolants secondaires juxtaposés sur la structure porteuse,
• une étanchéité secondaire comportant une pluralité de plaques métalliques secondaires étanches disposées sur les blocs isolants secondaires et soudées les unes aux autres,
• une isolation thermique primaire comportant une pluralité de blocs isolants primaires juxtaposés sur l'étanchéité secondaire,
• une étanchéité primaire comportant une pluralité de plaques métalliques primaires étanches disposées sur les blocs isolants primaires et soudées les unes aux autres, des organes de couplage mécanique secondaires s'étendant à travers l'isolation thermique secondaire au niveau des bords des blocs isolants secondaires et maintenant les blocs isolants secondaires en appui sur la structure porteuse, et
• des organes de couplage mécanique primaires s'étendant à travers l'isolation thermique primaire au niveau des bords des blocs isolants primaires et maintenant les blocs isolants primaires en appui sur l'étanchéité secondaire,
• caractérisée par le fait que les plaques métalliques primaires, et respectivement secondaires, sont disposées de manière que les bords des plaques métalliques soient décalés par rapport aux bords des blocs isolants primaires, et respectivement secondaires, sous-jacents ; que les plaques métalliques primaires, et respectivement secondaires, sont maintenues en appui sur les blocs isolants primaires, et respectivement secondaires, uniquement par les organes de couplage mécanique primaires, et respectivement secondaires,
• et que les organes de couplage mécanique primaires, et respectivement secondaires, sont attachés aux plaques métalliques primaires, et respectivement secondaires, au niveau de points d'attache distants des bords des plaques métalliques primaires, et respectivement secondaires.

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 insulating blocks juxtaposed on the supporting structure,
• a secondary seal comprising 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 having a plurality of sealed primary metal plates disposed 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 now the secondary insulating blocks bearing 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 by the fact that the primary and secondary metal plates are arranged in such a way that the edges of the metal plates are offset with respect to the edges of the primary and secondary secondary insulation blocks underlying them; that the primary and secondary metal plates are held in abutment on the primary and secondary insulation blocks, solely by the primary and secondary mechanical coupling members, respectively
• and that the primary, and respectively secondary, mechanical coupling members are attached to the primary and secondary metal plates at points of attachment distant from the edges of the primary and secondary metal plates.

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 contour shape can be every time rectangular, square, hexagonal or other shape for paving the plane.

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 insulator block, and respectively secondary, is each time delimited by shims introduced into a groove wider than the groove, the wedges leaving the channels in said groove between the primary and secondary insulation block, and the corrugation of a primary, and respectively secondary, sealing plate, 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 adapted to let through a primary mechanical coupling member, and respectively secondary.

According to one embodiment, the primary and secondary insulation blocks comprise sections cut at the corners of said primary and secondary insulation blocks, respectively the cut edges of four primary and secondary secondary insulation blocks, adjacent at a corner each defining a housing capable of passing 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.

• une première partie qui forme le pied du coupleur et comporte un carter externe, ledit carter externe étant fixé sur la structure, ledit carter renfermant un bouchon en matière thermiquement isolante et un moyen élastique, qui pousse ledit bouchon contre la structure de retenue par l'intermédiaire d'un écrou ;
• une deuxième partie, qui forme la tête du coupleur et comporte un carter externe solidaire de l'élément, ledit carter externe renfermant une bague thermiquement isolante et un manchon sensiblement cylindrique fileté intérieurement à ses deux extrémités, le filetage le plus éloigné de la structure de retenue recevant un embout équipé d'une collerette, qui vient en appui sur une plaque portée par la deuxième paroi de l'élément, le carter étant solidaire d'une platine périphérique mise en place dans un embrèvement compris entre ladite plaque et la deuxième paroi de l'élément ;
• et enfin une première tige filetée à ses deux extrémités et vissée d'un côté dans le manchon de la tête du coupleur et de l'autre, dans l'écrou du pied dudit coupleur, le vissage de ladite première tige assurant le maintien de l'élément contre la structure de retenue.

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 fastened to the structure, said casing enclosing a cap made of thermally insulating material and an elastic means, which pushes said cap against the retaining structure by the intermediate 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 both ends, the thread farthest from the structure of retaining receiving a nozzle equipped with a collar, 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 both ends and screwed on one side in the sleeve of the coupler head and the other in 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 fitting comprising, in a complementary casing of the same structure as that of the coupler head, on the one hand, an elastic means interposed between a flange of the second rod and the complementary casing and, on the other hand, a threaded sleeve including a collar allows, by welding on the metal plate, to seal between the outer space and the inside 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 in a structure carrying the the ship and the sheets to be welded constitute, after welding, a sealing barrier of 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 bearing 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.

• la figure 1 représente, vu en plan, le positionnement relatif d'une unité de barrière étanche et d'une unité de barrière isolante pour une première variante de mise en oeuvre de l'invention ;
• la figure 1A représente partiellement, vu en plan, une paroi de cuve étanche et isolante comportant un assemblage d'unités de barrière étanches et d'unités de barrière isolantes sous-jacentes, la barrière isolante étant recouverte par la barrière étanche sur seulement une partie de sa surface ;
• la figure 2 représente une paroi de cuve selon un premier mode de réalisation vue en coupe selon la ligne II-II de la figure 1 ;
• la figure 3 représente une variante de réalisation des gorges où sont mises en place les ondulations des barrières d'étanchéité primaire et secondaire ;
• la figure 4 représente, en coupe perpendiculairement à la structure porteuses, la constitution d'un coupleur secondaire retenant une paroi de cuve étanche et isolante pour assurer sa cohésion avec la structure porteuse, la paroi de cuve pouvant être, dans cette figure, équipée d'une seule barrière d'isolation thermique et d'une seule barrière d'étanchéité ;
• la figure 5 représente en coupe perpendiculairement à la structure porteuse, un coupleur primaire destiné à assurer la cohésion entre une barrière primaire et une barrière secondaire sous-jacente, elle-même retenue sur la structure porteuse par un coupleur secondaire tel que celui représenté sur la figure 4, les deux coupleurs étant coaxiaux ;
• la figure 6 représente en détail le pied du coupleur secondaire de la figure 4, vu, dans l'axe de sa tige, selon une coupe perpendiculaire audit axe faite au niveau de l'écrou prisonnier ;
• la figure 7 représente, vue en plan, une coupe de la tête d'un coupleur primaire ou secondaire selon les figures 4 et 5, faite au niveau de la platine mise en place au-dessous de la barrière d'étanchéité primaire ou secondaire ;
• la figure 8 est une vue analogue à la figure 2 représentant une paroi de cuve selon un deuxième mode de réalisation, la barrière secondaire étant retenue contre la structure porteuse par des coupleurs secondaires et la barrière primaire étant retenue sur la barrière secondaire par des coupleurs primaires, les deux types de coupleurs étant décalés dans les deux directions des gorges pratiquées dans les unités d'isolation primaire et secondaire ;
• la figure 9 représente, en perspective, une unité de la barrière d'isolation primaire et une unité de la barrière d'isolation secondaire de la paroi de la figure 8, les flèches montrant le positionnement des coupleurs primaires et secondaires ;
• la figure 10 représente en détail l'embase, qui permet l'arrimage du pied d'un coupleur primaire, dans le mode de réalisation des figures 8 et 9 ;
• la figure 11 représente le positionnement d'un organe d'appui en relief sur la barrière d'étanchéité primaire, au droit d'un organe de couplage de la barrière primaire, à la jonction de deux éléments adjacents de la barrière isolante primaire, cette vue étant une coupe partielle réalisée perpendiculairement à la structure porteuse et à la ligne moyenne d'une ondulation de la barrière d'étanchéité primaire ;
• la figure 12 représente, selon une coupe analogue à celle de la figure 11, l'utilisation d'un organe d'appui pour un appareil destiné à plaquer l'une contre l'autre les bordures de deux tôles de barrière d'étanchéité primaire que l'on désire souder à clin pour assurer l'étanchéité ;
• la figure 13 est une représentation schématique écorchée d'une cuve de navire méthanier et d'un terminal de chargement/déchargement de cette cuve.

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.
On this drawing :

• the figure 1 represents, in plan, the relative positioning of a sealed barrier unit and an insulating barrier unit for a first variant embodiment of the invention;
• the Figure 1A partially shows, in plan view, a sealed and insulating tank wall having an assembly of sealed barrier units and underlying insulating barrier units, the insulating barrier being covered by the impervious barrier on only a portion of its surface ;
• the figure 2 represents a vessel wall according to a first embodiment, seen in section along line II-II of FIG. figure 1 ;
• the figure 3 represents an alternative embodiment of the grooves where are placed the corrugations of the primary and secondary sealing barriers;
• the figure 4 represents, in section perpendicularly to the carrier structure, the constitution of a secondary coupler retaining a sealed and insulating tank wall to ensure its cohesion with the bearing structure, the tank wall can be, in this figure, equipped with a single thermal insulation barrier and a single sealing barrier;
• the figure 5 is a cross-section perpendicular to the carrier structure, a primary coupler for ensuring cohesion between a primary barrier and an underlying secondary barrier, itself retained on the carrier structure by a secondary coupler such as that shown on the figure 4 both couplers being coaxial;
• the figure 6 represents in detail the foot of the secondary coupler of the figure 4 , seen, in the axis of its stem, in a section perpendicular to said axis made at the level of the prisoner nut;
• the figure 7 represents, in plan view, a section of the head of a primary or secondary coupler according to the Figures 4 and 5 , made at the stage set up below the primary or secondary sealing barrier;
• the figure 8 is a view similar to the figure 2 representing a vessel wall according to a second embodiment, the secondary barrier being retained against the carrier structure by secondary couplers and the primary barrier being retained on the secondary barrier by primary couplers, the two types of couplers being offset in both groove directions in primary and secondary insulation units;
• the figure 9 represents, in perspective, a unit of the primary insulation barrier and a unit of the secondary insulation barrier of the wall of the figure 8 arrows showing the positioning of the primary and secondary couplers;
• the figure 10 shows in detail the base, which allows the docking of the foot of a primary coupler, in the embodiment of Figures 8 and 9 ;
• the figure 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 cut made perpendicularly to the supporting structure and the mean line of a corrugation of the primary sealing barrier;
• the figure 12 represents, in a section similar to that of the figure 11 the use of a support member for an apparatus intended to press against one another the edges of two sheets of primary sealing barrier which it is desired to weld clinically to ensure sealing;
• the figure 13 is a cutaway schematic representation of a tank of LNG tanker and a loading / unloading terminal of this tank.

Referring to Figures 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 pavers 28, respectively primary 29, consists of a foam panel thermally insulating 1a, respectively 2a, of generally quadrangular shape; each panel 1a, respectively 2a is covered, on its large faces, a plywood bottom plate 1b, respectively 2b , 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.

1 cover plates c and 2 c comprise grooves 5 having a quadrangular cross section, said grooves penetrating to foam layers 1 and 2a. Flat areas 46 are delimited between these grooves 5.

Each of the insulating barriers, secondary 1 and primary 2 respectively, carries on its wall farthest from the supporting structure 3, a sheet of metal, for example stainless steel, which constitutes a secondary, secondary or secondary 6, 7. each of the secondary sealing barrier 6 and respectively 7 is primary in the form of an assembly of rectangular metal plates, secondary 25 and primary 25 has respectively, which comprise in each case the corrugations 8 having a V , 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 respectively 25 a primary are made in two orthogonal directions, at equal distances, so that the network of corrugations defines flat inter-corrugation areas 40 of square shape (views perpendicular to the carrier structure 3), as is clearly visible on the Figures 1 and 1A for the secondary barrier. The primary barrier can be realized identically.

The secondary 25 and primary 25 a metal plates are arranged on the secondary insulating pavers 28 and 29, respectively, so that the corrugations 8 are in each case housed in the grooves 5 of the underlying insulating pavers, whereas the planar zones 40 rest on the cover plate 1c or 2c corresponding in a flat area 46.

The figure 3 represents a preferred variant of the 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 spacers 9, which, at their upper part and at the bend of the V, leave free zones, which constitute channels in which nitrogen can be circulated, between the secondary or primary barrier 6 and the insulating pavers secondary 28 or primary 29. These channels are an interesting device for 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. Slots of relaxation can be provided below the grooves 5.

The maintenance of 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 mechanical coupling members, whose position is systematically around the periphery of the insulating pavers. 28 and 29 to maintain.

The Figures 1 and 1 a represent the relative arrangement of the secondary insulating barrier 1 and the secondary watertight 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 At the edges of the secondary insulating pavers 28 are positioned at the center of the square inter-corrugation areas 40 of the secondary metal plate 25. The lines 35 designate overlapping areas 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 because of the elasticity imparted by the corrugations 8.

We will now describe a first embodiment of the vessel wall. The figure 2 provides a global representation of this first embodiment, and the Figures 4 and 5 give a detailed representation of the mechanical coupling members.

As it is clearly visible on the figure 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 passes through the secondary insulating barrier 1. times, 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 pads 28, respectively primary 29, and by notches angle 13 formed at the corners of the secondary insulating blocks 28, respectively primary 29. The complete housing of a secondary coupler 41, respectively primary 42, is constituted by two notches 12 formed in two adjacent insulating pavers or by the four notches 13 of four adjacent 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. on the 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 1 c of a secondary insulating pad 28. The coupler foot 15 comprises a housing 15 welded to the supporting structure 3. the casing 15 a is substantially cylindrical and contains a stack of Belleville washers 15b and a nut 15c screwed on the rod 14. the nut 15 c has a square shape and the nut angles rub on the housing 15 a so as to prevent rotation of the nut 15 c. The bottom plate 1b of the insulating pad secondary 28 is based on a smoothing wedge 17. The smoothing wedge 17 ensures the flatness of the support and makes possible partial disassembly of the insulation.

The cover plate 1c of the secondary insulating block 28 has a recess for the passage of a cylindrical housing 19, which externally defines the head 16. This housing 19 is constituted by a cylindrical punch formed in the center of a square fixing plate 18. The cylindrical housing 19 contains a thermally 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 that of the threaded ends of the rod 14, which does not cooperate with the nut 15 c . The plate 18 is positioned in a countersink 22 of the cover plate 1c and is covered by the secondary sealing barrier 6. A flanged edge 37 of the cylindrical housing 19 prevents any movement of the plate 18 and therefore transmits the forces of tearing supported by the secondary insulating pad 28 to the supporting structure 3 via the rod 14. The elastic clearance obtained thanks to the Belleville washers 15 b compensates for thermal contractions and possible dynamic deformations of the shell.

Having provided a threaded bore on the side of the sleeve 21 opposite the rod 14, allows the introduction into this bore of the threaded portion 23, a male end 24, having a flange 24 a . 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 lid 1 tbsp . The flange 24 has allows the achievement of a tight welding on the secondary metal plate 25 about said bore to re-seal at that 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 means of a weld. blink.

On the figure 5 represents the implementation of the secondary coupler 41, which has just been described, for coaxially fixing a primary coupler 42 such as that shown in FIG. figure 2 . The left part of the figure 5 corresponds to the head 16 of the secondary coupler 41 shown in detail on the figure 4 , With the difference that it has replaced the pin connector 24 by a socket 26 having a threaded bore on the far side of the supporting structure 3. The mouthpiece 26 also includes a peripheral flange 26 is likely to 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 in 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 rupture in the connection zone of the two diameters if the forces exerted on the organs 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 2 c of two or four primary insulating pavers 29. This connector 30 comprises a housing 30 has all to analogous to the cylindrical housing 19 of the head of the secondary coupler 41 of the figure 4 . The casing 30 is a cylindrical stamp obtained in the central zone of a plate 18 identical to that of the figure 4 and positioned in the same way as the primary metal plate 25 a. The plate 18 is quadrangular. Inside the housing 30 a are arranged Belleville washers 30b and a flange 30c of the rod 27 based on the Belleville washers 30 b. In the housing 30a, is positioned a threaded sleeve 31 having, along its axis, an external thread referred to in the cylindrical casing 30a, and a threaded hole 38 facing the interior of the tank, allowing the possible fixing of relief means of the same type that the male end 24 shown on the figure 4 , not shown on the figure 5 . The threaded sleeve 31 has a peripheral flange 31a, which can be welded to a primary metal plate 25 a. The coupling members, which have just been described, allow a slight relative rotation of the various elements assembled.

The support of the flange 24a, 31a respectively on the secondary metal plate 25, 25 respectively have primary, keeps the secondary sealing barrier 1, 2 respectively primary, resting on the cover plates 1 c, 2c respectively, secondary insulating pavers 28, primary 29 respectively. With sufficient density of the primary and secondary couplers, no other fastener is therefore 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.

The Figures 8 to 10 represent a second embodiment of a tank wall, in which the coupling, which retains the primary 2 and secondary 1 insulating barriers against the carrier structure 3, is achieved by primary 33 and secondary 32 couplers, which are not aligned in their part where they pass through the primary and secondary insulating barriers 1. In this embodiment, the primary and secondary insulating blocks 29 and 28 are identical to those corresponding to the Figures 1 and 1A but they are arranged differently. Instead of having a primary insulating pad 29 exactly in line with a secondary insulating pad 28, it is intended here to offset the primary insulating pad 29 by relative to the secondary insulating pavers 29 by a certain distance in both directions of the plane of the vessel wall. The lateral offset distance 61 is less than half the width of the blocks in the example shown in FIGS. Figures 8 and 9 . The longitudinal offset distance 62 is equal to the longitudinal distance between two corrugations 8 in the example shown in FIG. figure 9 .

Under these conditions, the primary 33 and secondary 32 couplers are no longer in alignment with each other as it is clearly visible on the figure 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 S1, S2 and S3. All couplers were not represented on the figure 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 is constituted by a rod 32, which by one of its ends is linked to the 3 and with its other end supporting structure, is bonded to the one cover wall c secondary insulating pavers 28. The aforementioned links can be made identically to the first embodiment.

The primary coupler 33 includes a rod 33a, which by one of its ends is linked to 2c cover wall two or four primary insulating blocks 29 and by its other end is linked to the one cover wall c d a secondary insulating pad 28 remote from the edges thereof. The connection of this rod 33 a with the lid walls 2c is carried out with a device corresponding exactly to that illustrated on the right side of the figure 5 and previously described. The connecting rod 33 is with the cover wall 1c is performed by cooperation of a thread of the rod 33 a with a base 34 shown in figure 10 . At the crossing of the secondary sealing barrier 6, the rod 33a has a flange 33 b which is welded to the plate secondary metal 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.

On the figure 11 , a section is shown, a primary or secondary sealed barrier equipped with a male end 24 such as that previously described and shown on the figure 4 . The elements already described and which are found in the realization of Figures 11 and 12 have been designated in these new figures by the same references as for the 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 the figure 11 represents a secondary barrier but the situation would be identical if it were a primary barrier. The adjacency zone of two secondary insulating pavers 28 with their plywood cover plates 1c is seen . As illustrated on Figures 1 and 1A , coupling elements (not visible on the figure 11 ) are arranged in the plane 51 located between two adjacent secondary insulating blocks 28. The secondary sealing barrier 6 is constituted by the assembly of the plate plates 25, this assembly is done by a weld seam 52 of two adjacent plate plates.

The figure 12 represents an apparatus set up on the wall area described above and represented on the figure 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.

With reference to the figure 13 , a cutaway view of a LNG tanker 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 waterproof barrier and the double hull 72 of the vessel, and two insulating barriers respectively arranged between the primary watertight barrier and the secondary watertight barrier and between the secondary watertight barrier and the double shell 72.

In a manner known per se, loading / unloading lines 73 arranged on the upper deck of the ship can be connected, by means of appropriate connectors, to a marine or port terminal to transfer a cargo of LNG from or to the tank 71.

The figure 13 represents an example of a marine terminal comprising a loading and unloading station 75, an underwater pipe 76 and an onshore installation 77. The loading and unloading station 75 is an off-shore fixed 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 that can connect to the loading / unloading pipes 73. The movable arm 74 can be adapted to all gauges 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 in parentheses can not be interpreted as a limitation of the claim.

Claims (12)

1. Sealed and thermally insulative tank comprising: a retaining structure (3), an insulation barrier comprising a plurality of insulation elements (1, 2) juxtaposed on the retaining structure (3)
   a sealing barrier (6, 7) supported by the insulation barrier and comprising a plurality of plates (25) and a coupler for retaining, relative to the retaining structure (3) an insulation element (1, 2) subjected to forces liable to lead to its separation from said structure, said insulation 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 (1c, 2c), farther from it,
   the coupler including:

   - a first part, the forms the base (15) of the coupler and includes an external casing (15a), said external casing being fixed to the retaining structure (3),

   - a second part, that forms the head (16) of the coupler;

   - and finally, a rod (4) threaded at its two ends, characterized in that

   said casing encloses a thermally insulative material plug (15d) and a spring means which pushes said plug against the retaining structure via a nut (15c),
   the second part of said coupler including an external casing (19) fastened to the insulative element, said external casing enclosing a thermally insulative ring (20) and a substantially cylindrical sleeve (21) internally threaded at both its ends, the thread farthest from the retaining structure (3) receiving an end-piece (24, 26) equipped with a flange (24a, 26a), which comes to bear on a plate (25) of the sealing barrier carried by the second wall of the insulative element, the casing (19) being fastened to a peripheral plate (18) placed in a spot-facing comprised between said plate (25) and the second wall of the insulative element, and the threaded rod being screwed at one end into the sleeve (21) of the head (16) of the coupler and at the other end into the nut (15c) of the base (15) of said coupler, the screwing of said first rod (14) assuring the retention of the insulative element against the retaining structure (3).
2. Tank according to Claim 1, characterized in that the insulative element (1) retained relative to the retaining structure (3) is associated with a complementary insulative element (2) covered with a metal plate (25a) on the side opposite the retaining structure (3) and in 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 connector (30) fastened to the complementary insulative element (2), said connector (30) including, in a complementary casing (30a) with the same structure as that of the head (16), on the one hand, spring means (30b) disposed between an edge (30c) of the second rod (27) and the complementary casing (30a) and, on the other hand, an internally-threaded sleeve (31) a flange (31a) of which, by being welded to the metal plate (25a) enables sealing to be assured between the exterior space and the interior of the complementary insulative element.
3. Tank according to one of Claims 1 to 2, characterized in that the nut (15c) of the base (15) has a square exterior shape the corners of which rub on the casing (15a) or on a part that is connected to it.
4. Tank according to one of Claims 1 to 3, characterized in that the plates (18) of the casing (19) and of the complementary casing (30a) of the coupler have a rectangular shape.
5. Tank according to one of Claims 1 to 4, characterized in that the second rod (27) has at least one portion of smaller section than the first rod (14).
6. Tank according to one of Claims 1 to 5, characterized in that the supporting structure (3) is the double hull of a ship.
7. Tank according to Claim 2, characterized in that the complementary insulative element with which the coupler is associated is a primary barrier insulative element (2), the insulative element nearer the supporting structure (3) being a secondary barrier inslative element (1).
8. Tank according to Claims 2 and 6 considered simultaneously, characterized in that the internally-threaded sleeve (31) receives, on the side farther from the supporting structure (3), the threaded end of a means (24) projecting relative to the metal plate (25a), which means covers the complementary insulative element (2).
9. Tank according to one of Claims 6 to 8, characterized in that the first wall (1b) of the insulative element associated with the coupler bears against the supporting structure with smoothing shims (17) disposed between them.
10. Tank according to one of Claims 1 to 9, characterized in that the plate (25, 25a) associated with that of the walls of the insulative element and/or of the complementary insulative element that is farther from the retaining structure (3), is a thin metal plate formed by welding identical sections.
11. Tank according to Claim 10, characterized in that the plate sections are lap welded and include corrugations (8) in two orthogonal directions.
12. Tank according to Claim 10, characterized in that the plate sections are welded with raised edges.

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