EP0064886B1 - Fluid-tight and heat-insulating tank integrated in a ship's hull structure - Google Patents

Description

The present invention relates to the production of sealed and thermally insulating tanks intended for the transport by sea of liquefied gases, and, in particular, for the transport of liquefied natural gases with a high methane content.

Such watertight and insulating tanks, integrated into the carrying structure of a ship, are of the type which include two successive sealing barriers, one primary in the container with the product contained in the tank and the other secondary disposed between the primary barrier and the ship's supporting structure, these two sealing barriers being alternated with two thermally insulating barriers, the secondary insulating barrier consisting of a set of substantially parallelepipedal heat-insulating elements fixed against the carrying structure of the ship by means of retainer integral with the supporting structure, which cooperate with fasteners arranged at the edge of the elements of the secondary insulating barrier, said elements being separated from each other by substantially rectilinear joint zones where the aforementioned retaining members are located, the barrier primary insulation also consisting of a set of heat-insulating elements while pressing on the secondary sealing barrier, the secondary sealing barrier being constituted by metal strakes with raised edges towards the inside of the tank, said strakes being made of thin sheet metal with low coefficient of expansion and being welded edge on board, by their raised edges, on both sides of a welding wing, which is mechanically retained on the elements of the secondary insulating barrier.

Tanks of this kind are known in particular from FR-A-24 13 260.

During the transport by sea of a mass of liquefied gas, in such tanks, the sealing barriers and the thermally insulating barriers are subjected to forces causing deformations of said barriers.

With the aim, in particular, of absorbing such deformations at the level of the primary sealing barrier, provision is generally made for an assembly of welded invar strakes with raised edges.

Such an assembly with raised edges, which makes it possible to improve the life of the primary sealing barrier by better absorption of deformations, is however relatively expensive to produce. Indeed, before proceeding to the assembly of strakes, it is necessary to carry out the raising of the edges.

We also know from FR-A-2286341 and FR-A-1407 871 tanks intended for the transport of liquefied gases having a structure different from those defined above, but in which the sheets of the primary sealing barrier are welded overlapping.

The object of the invention is, above all, to provide a tank of the kind defined above in which the primary sealing barrier can be produced in a simpler manner while retaining the usual qualities, in particular a satisfactory lifetime.

According to the invention, a tank of the kind defined above is characterized in that, on the one hand, the primary insulating barrier is held in abutment on the secondary sealing barrier by means of anchoring members fixed to the carrying structure of the ship. , said anchoring members passing through the secondary sealing barrier, the sealing of the secondary sealing barrier being maintained by means of welds which connect the anchoring member to the strakes of the secondary sealing barrier, and that , on the other hand, the primary sealing barrier consists, in a manner known per se, of an assembly of sheets whose edges are welded overlapping, a sheet having part of its edge in direct contact with the inside of the tank, while the other part is in contact with the primary insulating barrier and is fixed on it, the connections of the angles of several adjacent sheets being made by welding.

Thanks to the invention, the primary insulating barrier constitutes a support surface for the primary sealing barrier, which is perfectly retained relative to the supporting structure. The deformations of the primary insulating barrier and of the primary sealing barrier will be reduced during transport, so that the strength and the service life of an assembly of sheets whose edges are welded overlapping will be satisfactory.

According to a first type of construction, provision is made for the fixing of a portion of the edge of the sheets on the primary insulating barrier is carried out by localized welds on metal inserts provided on the corresponding face of the elements of the primary insulating barrier.

According to a second type of construction, it is provided that each element of the primary insulating barrier comprises, on the side of the interior of the tank, a plate of unexpanded material and that the fixing of a part of the edge of the sheets on the primary insulating barrier is produced by screws regularly distributed over the edge portion concerned, said screws being screwed into the aforementioned plates.

In each of these two types of construction, there are two possibilities for making the connection of the angles of four adjacent sheets. According to the first possibility, the welding, which ensures the connection of several adjacent sheets is carried out on a metal piece of connection door by an element of the primary insulating barrier; in this case, either the metal connecting part is a metal insert, or else each element of the primary insulating barrier comprises, on the side of the interior of the tank, a plate of unexpanded material and the metallic connecting piece is a metallic sheet fixed by screwing on said plate. According to the second possibility, the welding, which ensures the connection of several adjacent sheets is carried out by covering the connection area of said sheets by a cover plate disposed towards the inside of the tank and welded to the sheets over its entire periphery.

In a first embodiment, the sheets of the primary sealing barrier are flat invar sheets having a thickness, preferably between 0.5 and 2 mm. In a second embodiment, the sheets of the primary sealing barrier are embossed sheets of cryogenic steel having a thickness between 1 and 2 mm, the depth of the corrugations of the embossing being between 30 and 120 mm.

In a first variant, the elements of the secondary insulation barrier are panels of cellular material and those of the primary insulation barrier are boxes partitioned internally and filled with a particulate thermally insulating material.

In a second variant, the elements of the secondary insulation barrier are boxes filled with a thermally insulating particulate material and the elements of the primary insulation barrier are panels of cellular material, the large face of which faces towards the inside the tank is covered with a plate of solid unexpanded material. Preferably, the aforementioned unexpanded solid material plates are plywood plates.

According to an advantageous embodiment, the elements of the secondary insulation barrier are rectangular parallelepipeds all identical and the retaining members used for holding the secondary insulation barrier on the supporting structure are aligned in two perpendicular directions, the members of 'acrage associated with the primary insulation barrier being regularly arranged in the said alignments; the retaining members are threaded studs welded by their base to the load-bearing structure of the ship, the fastenings associated therewith are plates, which are supported by screwing a nut on the associated stud, on a zone of the elements of the secondary insulation barrier, and the anchoring members are tubes screwed onto certain studs capable of constituting retaining members; each of said tubes carries, at its end furthest from the support structure, on the one hand, a support flange coming at the level of the secondary sealing barrier and, on the other hand, a nozzle comprising, in the first place, a base, which encloses the strake of the secondary sealing barrier between it and the support flange and makes it possible to seal by welding its edges on the strakes of the secondary sealing barrier, and, secondly , a threaded part with which a fastener cooperates, which maintains relative to the support structure, the elements of the primary insulation barrier and supports them on the secondary sealing barrier.

In the first variant defined above, it is advantageously provided that the panels of cellular material have their two large faces covered with a sheet of unexpanded solid material, the fastenings associated with the retaining members of the secondary insulation barrier s' pressing simultaneously on two parallel protruding edges of the plates associated with two adjacent panels and arranged in the vicinity of the support structure, the plates disposed in the vicinity of the secondary sealing barrier comprising parallel grooves, in which the wings used for welding are engaged edge to edge of the metal strakes of the secondary sealing barrier; the grooves in which the welding wings are engaged are parallel to one of the alignments of retaining members; the boxes of the primary insulation barrier have two edges and internal partitions parallel to the welding wings, which protrude from the secondary sealing barrier, said wings being housed in gutters formed in the parallel partitions said wings; the edges of the primary insulation barrier elements, which are parallel to the weld flanges, have attached lugs which cooperate with the fasteners associated with the ends of the anchoring members.

In the second variant mentioned above, provision is advantageously made for each box of the secondary insulation barrier to carry, on its large face furthest from the support structure, parallel grooves in which the wings used for edge-to-edge welding are engaged. metal strakes of the secondary sealing barrier and, on each of its edges perpendicular to the aforementioned grooves, in the vicinity of the support structure, an attached tenon on which bear the fastenings associated with the retaining members, the box edges, which only carry no studs, coming into contact with a similar border of an adjacent box; the panels of cellular material of the primary insulation barrier comprise, on their face in contact with the secondary sealing barrier, gutters in which the welding wings of the secondary sealing barrier are engaged, each panel being glued by its edges to the adjacent panels and being held in abutment on the secondary sealing barrier by at least one anchoring member, the fixing of which bears on the bottom of a well formed in the panel and closed by a plug; each box of the secondary insulation barrier is held on the supporting structure by four retaining members arranged at each of its angles, two of these four retaining members, arranged on the same perpendicular to the tenons of the box, carrying constituent tubes of 'anchors.

In the two variants below mention born, the grooves where the welding wings are engaged have preferably a T-shaped cross section, while the welding wings have an L-shaped cross section.

In a known manner, it is advantageously possible to provide that the elements of the secondary insulation barrier rest on the supporting structure by means of parallel slats resting on strands of polymerizable resin, these slats constituting, by discontinuous elements, a geometric surface. defined independent of random deviations of the carrier with respect to its theoretical surface. To reduce heat loss, it is provided that the areas of joint existing between the elements of the insulation barriers due to the presence of the retaining and anchoring members are filled with insulating material after tightening the fasteners and closed, behind the sheets constituting the sealing barriers, by slats supported in appropriate recesses made on the edges of the elements of the corresponding insulation barriers.

It was previously indicated that the sheets constituting the primary insulation barrier could be fixed on metal inserts; it can advantageously be provided that these metal inserts are pellets placed and maintained in perforations of corresponding shape made in the plate of the primary insulation barrier element, which the primary sealing barrier supports.

When cooling a tank according to the invention, there is a contraction due to the lowering of the temperature and this contraction results in tensile forces, which are exerted on the fasteners connecting the tank to the carrying structure of the ship. These efforts are particularly difficult to control in the tank angles, that is to say at the place where two panels are angularly connected; the difficulty is all the more significant as the coefficient of linear expansion of the primary sealing barrier is greater and the thickness of the sheets of the primary sealing barrier is greater.

According to a first variant intended to solve this problem, the tank angles are produced by means of a plurality of identical cross-pieces, arranged side by side and each consisting of two attachment half-wings and two support half-wings. tank, a hooking half-wing being in the extension of a support half-wing to constitute a wing of the cross-piece, the two wings of all the cross-pieces of the same angle connecting at the same edge substantially parallel to that of the angle of the tank in question, the half-wings for attaching the cross-pieces being fixed on the carrying structure of the ship and the half-wings supporting the cross-pieces being secured to the metal strakes of the secondary sealing barrier; in the angle of the support half-wings, which is oriented towards the side of the tank, the cross-pieces of the same tank angle support, on each of the support half-wings of the cross-piece, secondary shims held on several adjacent cross-pieces and covered , in the area of the angle of the angle iron to which they are fixed and of the side where the tank is located, of a sheet of the same metal as that of the strakes of the secondary sealing barrier, which are substantially in the same plane and come to weld on it; a connection angle is welded to the sheets covered by two adjacent secondary shims with a tank angle; primary wedges are arranged in the angle defined by the secondary wedges and fixed to the crosspieces by means of hooking members, which the secondary sealing barrier or its extension pass in leaktight manner, said primary wedges supporting a metal angle on which is welded the primary sealing barrier.

In a second variant intended to solve the problem posed by the realization of the tank angles, it is proposed that the tank angles are produced by means of a plurality of identical secondary brackets arranged side by side and connecting along the same substantially edge parallel to that of the tank angle considered, these secondary brackets each being carried by four tubular members located two by two in the same plane perpendicular to the abovementioned edge, one of the pairs of tubular members extending towards the tank to support a plurality of identical primary brackets arranged side by side and connecting along the same edge substantially parallel to that of the secondary brackets, the primary and secondary brackets carrying shims coated with a metal sheet of the same kind as that which constitutes the barrier 'corresponding seal, said sheet being welded to said barrier; the primary and secondary brackets each receive two wedges at right angles, the metal covering sheets of which are covered, in the angle which they form by a welded connection angle; the tubular members, which support the primary brackets, pass through the secondary sealing barrier or its extension in a leaktight manner, two square stiffeners being formed in each primary bracket on either side of the tubular members which support it; the secondary brackets include a stiffener at right angles to each pair of tubular members, which does not extend to a primary bracket; the primary and secondary brackets have the same length measured parallel to their edge and the plane of separation of two adjacent primary brackets is in line with a secondary bracket stiffener.

To better understand the object of the invention, we will now describe, by way of purely illustrative and nonlimiting examples, several embodiments shown in the accompanying drawing.

• - la figure 1 représente, en perspective, une première variante de réalisation de la paroi d'une cuve selon l'invention, cette variante étant illustrée par les figures 1 à 6;
• - la figure 2 représente, en détail, la coupe au droit d'un organe d'ancrage de la barrière d'isolation primaire, ladite coupe étant réalisée dans un plan passant par l'axe de l'organe d'ancrage et perpendiculaire 'à l'axe de la zone de joint, où de trouve ledit organe d'ancrage;
• - la figure 3 représente, en coupe perpendiculaire à une aile de soudure, le logement de ladite aile de soudure dans sa gouttière assosiée pratiquée dans un caisson de la barrière d'isolation primaire, cette coupe étant réalisée selon la ligne III-III de la figure 4;
• - la figure 4 représente, vue en plan un caisson de la barrière d'isolation primaire, dont la face supérieure a été partiellement arrachée, ce caisson étant supposé ne porter aucun insert de fixation de la barrière d'étanchéité primaire;
• - la figure 5 représente, en perspective, l'angle d'un caisson de la barrière d'isolation primaire;
• - la figure 6 représente, vue en plan la face d'un caisson d'isolation primaire, qui porte des inserts de fixation de la barrière d'étanchéité primaire, le caisson représenté étant celui qui se trouve au droit du raccordement de quantre tôles de la barrière d'étanchéité primaire;
• - les figures 7 à 10, représentent schématiquement en coupe quatre modes de réalisation possibles pour le maintien des inserts métalliques dans les parois des éléments de barrière d'isolation primaire;
• - la figure 11 représente, en perspective éclatée, une vue analogue à celle de la figure 1 pour une deuxième variante de réalisation de la cuve selon l'invention;
• - la figure 12 représente une coupe passant par l'axe d'un organe d'ancrage, cette coupe étant analogue à celle représentée sur la figur 2 mais correspondant à la variante de la figure 11;
• - la figure 13 représente une première variante de réalisation d'un angle de cuve, cette vue étant une coupe perpendiculaire à l'arête de la cuve;
• - la figure 14 représente, en perspective, deux croisillons utilisés pour le raccordement de la cuve à la structure porteuse du navire pour la variante de la figure 13;
• - la figure 15 représente une deuxième variante relative à la réalisation d'un angle d'une cuve selon l'invention, cette figure étant une coupe selon XV-XV de la figure 18;
• - la figure 16 représente une autre coupe parallèle à celle de la figure 15, selon XVI-XVI de la figure 18;
• - la figure 17 représente une vue en bout de l'alignement des équerres primaire et secondair du dispositif représenté sur les figures 15 et 16;
• - la figure 18 représente schématiquement une vue en élévation selon XVIII-XVIII de la figure 17;
• - la figure 19 représente une vue en plan selon XIX-XIX de la figure 17;
• - la figure 20 représente, en perspective, une variante de fixation de la barrière d'étanchéité primaire sur la barrière isolante primaire au moyen de vis, les raccordements d'angle se faisant sur un insert;
• - la figure 21 représente, en perspective, une première modification de la réalisation de la figure 20, dans laquelle les raccordements d'angle se font sur une feuille de liaison vissée sur la barrière isolante primaire;
• - la figure 22 représente, en perspective, une deuxième modification de la réalisation de la figure 20, dans laquelle les raccordements d'angle se font au moyen d'une plaque de recouvrement.

On this drawing:

• - Figure 1 shows, in perspective, a first alternative embodiment of the wall of a tank according to the invention, this variant being illustrated by Figures 1 to 6;
• - Figure 2 shows, in detail, the section in line with an anchoring member of the primary insulation barrier, said section being made in a plane passing through the axis of the anchoring member and perpendicular ' to the axis of the joint zone, where said anchor member is located;
• - Figure 3 shows, in section perpendicular to a welding wing, the housing of said welding wing in its associated gutter made in a box of the primary insulation barrier, this section being made along line III-III of the Figure 4;
• - Figure 4 shows, in plan view a box of the primary insulation barrier, the upper face of which has been partially cut away, this box being supposed to carry no attachment insert for fixing the primary sealing barrier;
• - Figure 5 shows, in perspective, the angle of a box of the primary insulation barrier;
• - Figure 6 shows, in plan view the face of a primary insulation box, which carries inserts for fixing the primary sealing barrier, the box shown being that which is located at the right of the connection of quanter sheets of the primary sealing barrier;
• - Figures 7 to 10 show schematically in section four possible embodiments for maintaining the metal inserts in the walls of the primary insulation barrier elements;
• - Figure 11 shows, in exploded perspective, a view similar to that of Figure 1 for a second alternative embodiment of the tank according to the invention;
• - Figure 12 shows a section through the axis of an anchor, this section being similar to that shown in Figure 2 but corresponding to the variant of Figure 11;
• - Figure 13 shows a first alternative embodiment of a tank angle, this view being a section perpendicular to the edge of the tank;
• - Figure 14 shows, in perspective, two braces used for the connection of the tank to the carrying structure of the ship for the variant of Figure 13;
• - Figure 15 shows a second variant relating to the production of an angle of a tank according to the invention, this figure being a section along XV-XV of Figure 18;
• - Figure 16 shows another section parallel to that of Figure 15, along XVI-XVI of Figure 18;
• - Figure 17 shows an end view of the alignment of the primary and secondary brackets of the device shown in Figures 15 and 16;
• - Figure 18 shows schematically an elevational view along XVIII-XVIII of Figure 17;
• - Figure 19 shows a plan view along XIX-XIX of Figure 17;
• - Figure 20 shows, in perspective, a variant of fixing the primary sealing barrier on the primary insulating barrier by means of screws, the corner connections being made on an insert;
• - Figure 21 shows, in perspective, a first modification of the embodiment of Figure 20, in which the corner connections are made on a connecting sheet screwed to the primary insulating barrier;
• - Figure 22 shows, in perspective, a second modification of the embodiment of Figure 20, in which the corner connections are made by means of a cover plate.

Referring to Figures 1 to 6 of the drawing, we see that there is shown a first embodiment of the sealed and insulating tank according to the invention; this tank is intended to be produced in a ship, for the transport of liquefied natural gas. The carrier structure of the ship, that is to say the double hull or the double partition, which supports the walls of the tank, has been designated by 1. Due to manufacturing tolerances, the wall of the supporting structure has local deformations, which could be troublesome for the production of the tank according to the invention; in known manner, there are on the wall 1, plywood slats 2, which rest on strands of polymerizable resin, and the positioning of the slats 2 is governed so that they define, discontinuously, a Theoretical surface independent of the more or less good conformation of the wall 1.

On the slats 2, the elements of the secondary insulation barrier designated by 3 as a whole are put in place. Each element 3 consists of a rectangular parallelepiped made of a cellular material such as a polyurethane foam with closed cells, for example; the foam block 3a is covered on its two large rectangular faces with a backing plate 3b, 3c; the plate 3b is supported on the slats 2; the plate 3c supports the secondary sealing barrier constituted by invar strakes 4 assembled by welding with raised edges, on either side of a welding wing 5. The plate 3b projects beyond the block of foam 3a all around the periphery of the block. The plate 3c has grooves 6 having a cross section in T, said grooves being intended to receive, as shown by the magnifying glass of FIG. 1, a welding wing 5 having a cross section in L. The grooves 6 are arranged perpendicular to the slats 2 and the primary insulation barrier elements 3 are surrounded, over the entire periphery of the plate 3b, by retaining members 7.

The retaining members 7 are threaded studs, which are welded by their base to the wall 1, perpendicular to the latter. The studs 7 are distributed in alignments parallel to two perpendicular directions, one of the directions being parallel to the slats 2. In the embodiment which is described, the alignments of studs 7, which are perpendicular to the slats 2, are spaced apart 1 m and aligns them studs 7, which are perpendicular to the previous ones, are spaced 3 m apart; this determines the dimensions of the secondary insulation barrier elements 3. The width of the strakes 4 is 50 cm and the two grooves 6 formed on each of the plates 3c are symmetrical with respect to the major axis of said plate 3c.

The retaining members 7 are associated with fasteners 8 constituted by square plates, which come to bear on the projecting edges of the plates 3b. The plates 8 are held by nuts 9, which are screwed onto the threaded studs 7. This ensures the maintenance of the elements 3 on the load-bearing structure 1 of the ship, with compensation for the thicknesses of the resin tubes on which the slats 2 rest thanks at the latitude of screwing on the threaded studs 7. The spacing of the studs 7 is chosen so that a stud 7 is located at each angle of the elements 3. On each of the studs 7 of the angles and on the studs 7 which are at one meter from each angle on each longitudinal edge of elements 3, a tubular member designated by 10 as a whole is connected, which member, taken in combination with the stud 7 associated therewith, constitutes an anchoring member intended for the fixing of the primary insulation barrier.

The tubular member 10 is screwed its base onto the stud 7 and is equipped at its other end with a support flange 11 which can come to bear in a recess 12 formed on the corresponding edge of the plate 3c. We therefore put in place, by screwing, the tubular members 10 and, when the screwing is done fully, the position of the flange 11 is blocked relative to the element 3 by means of any rotational stop, for example driving a pin. Again, the latitude of screwing the tubular members 10 onto the threaded studs 7 makes it possible to obtain perfect retention of the secondary insulating barrier by compensating for the variation in the thicknesses of the resin strands on which the slats rest. The upper face of the support flange 11 is located exactly at the level of the invar strake 4, for which it constitutes a support. In all the joint zones located to the right of the studs 7, insulating strips are put in place intended to fill the space 13 existing between two adjacent elements 3 and the joint zone is closed at the support flanges 11 by means of slats 14, which bear in recesses 12 and close the joint areas to form a continuous support for the secondary sealing barrier constituted by strakes 4.

In line with the support flanges 11, circular holes 15 are practiced in the strakes 4; these orifices 15 are located directly above a threaded housing formed in the central zone of the flange 11, housing where the threaded base is screwed with a nozzle designated by 16 as a whole. The endpiece 16 comprises a base 17 which, by screwing the endpiece into the threaded housing of the support flange 11, can come to bear on the strake 4, all around the circular orifice 15. It then suffices to weld at the periphery of the base 17 for sealing around the anchoring member 7, 10, 16. The end piece 16 has, at its upper part, a threaded zone with which a nut 18 cooperates.

The secondary sealing barrier, produced by the straps in invar 4 welded to the raised edge on either side of the welding wings in invar 5, constitutes a tight barrier, on which the primary insulation barrier is placed. of the tank according to the invention. This primary insulation barrier consists of plywood boxes designated by 19 as a whole. Each box 19 has an interior partition parallel to its edges and has the general shape of a rectangular parallelepiped having 1 meter long and 0.95 m wide; on the two edges separated by a distance of 0.95 m, there is reported a stud 20, which has at its ends a recess 21. The elements 19 are arranged so that the end piece 16 is at each of their angles. It is therefore possible to secure the elements 19 by means of a plate 22, which is supported in the recesses 21 of the studs 20 and which is held by the nuts 18 associated with the end pieces 16; the fasteners formed by the plates 22 are supported on four adjacent recesses 21, the plate 22 can advantageously have a square shape. When the elements 19 are mounted side by side, insulating strips 23 are inserted below the studs 20; the joint zones formed above the tenons 20 are finally filled with insulation and closed by an attached batten 24.

The elements 19 of the primary insulating barrier have an internal partition formed by three spacers 25 parallel to the studs 20 and a plurality of spacers 26 perpendicular to the spacers 25. One of the spacers 25 is arranged in a plane of symmetry of the element 19; the other two spacers 25 are thicker than the spacers 26 and are symmetrical with respect to the center of the element 19; these two other spacers 25 are located at the right of two welding wings 5 of the secondary sealing barrier and they comprise on their lower face a gutter 27, which constitutes a housing for the welding wings 5 forming a relief. In order for the wings 5 to be able to enter the gutters 27, provision is made to produce the corresponding face of the elements 19 in three panels 19a separated from one another by the two gutters 27. In this way, the panels 19a can rest on the metal strakes 4, despite the presence of the projections formed by the welding wings 5.

Along their edges, which are perpendicular to the tenons 20, the elements 19 come to bear against each other, while two adjacent elements 19 are separated from each other along the other edges by a batten 24 5 cm wide; in this way, the module occupied by a element 19 is a square of one meter by one meter. Each element 19 is filled with a particular thermally insulating material, such as perlite. On its face opposite to that which is occupied by the panels 19a, each element 19 comprises a counter-plate 19b where metal inserts 28 are put in place allowing the fixing of the primary sealing barrier.

Figures 7 to 10 show four alternative embodiments of the metal inserts 28 on elements 19 of primary insulating barrier formed according to the first variant described above. In FIG. 7, we can see an insert 28a constituted by a circular hollow bowl, the edges of which are glued in a recess made on the underside of the plate 19b, the bowl 28a being, moreover, supported by a spacer 25 or 26 of element 19. In FIG. 8, it can be seen that the insert 28b consists of a circular plate having a flange on one of its faces, said flange being blocked by tabs 29 stapled on the plate 19b to inside the element 19. In FIG. 9, it can be seen that the insert 28c is produced by the assembly by riveting of two half-inserts, one of which comprises a base 30 fixed on the plate 19b to the inside the element 19 and the other of which constitutes a cap which comes to cap the first half-insert. Finally, in FIG. 10, the insert 28d consists of a plate comprising a snap stud 31 at its lower part, said stud coming to snap into a clips 32 fixed in a recess on the internal face of the plate 19b. The types of embodiment of the metal inserts 28 can be used in the same way for primary insulating barrier elements according to the second variant, which will be described in more detail and which corresponds to FIGS. 11 and 12: the only difference is that, if in the first variant, each insert is supported, in its box, by internal partitions, it is continuously supported, in the second variant, by the cellular material of the element.

The primary sealing barrier is constituted by an assembly of rectangular sheets 33, which are welded to each other overlapping. A sheet 33 has two edges disposed above the adjacent sheet and two edges disposed below the adjacent sheet. The two edges, which are arranged above the adjacent sheets which they cover, are welded over their entire length to said sheets. The two edges, which are located below the adjacent sheets, are welded to the inserts 28 formed on the plates 19b of the elements 19. To achieve this welding, circular holes 34 of smaller diameter are formed on the corresponding edge of the sheets 33 to the diameter of the inserts 28, with which they cooperate. These orifices are each positioned in line with an insert 28. The sheets 33 have a width of 2 meters and a length of 3 meters; each is arranged so that its median longitudinal axis coincides with the median longitudinal axis of an element 19. In this way, the overlapping of two adjacent sheets 33 takes place at the level of the median axis of an element 19 and it is on this median axis that the inserts used for welding will be found. In the example described, the orifices 34 are distributed every 33 cm and it is arranged so that the connection zone 35 of four sheets 33 is located in line with the central point of an element 19; at this central point, there is an insert 28 having a larger diameter than that of the inserts, which are located at the right of the orifices 34. It is therefore seen that there will be three kinds of elements 19: some will have on their plate 19b five inserts arranged in a cross, as shown in FIG. 6, the central insert having a larger diameter than the other two; the others will have three inserts 28 arranged along one or the other of their two axes of symmetry; the latter will have no insert.

The welds made over the entire edge of the orifices 34 ensure the connection of the corresponding edge of the sheet 33 with the primary insulation barrier; the overlap by the adjacent sheet 33, with welding along the edge of said sheet 33, seals the primary sealing barrier, it being understood that in the zones 35, the welds are made in a sealed manner on the insert 28 of large diameter, which is located in line with said zone, the angles of the sheets 33 being cut down so that each sheet has a weld zone ensuring its connection with the insert 28. In a first alternative embodiment, the sheets 33 are invar sheets having a thickness of approximately 1 millimeter; in another embodiment, the sheets 33 are sheets of cryogenic steel, for example stainless steel with 18% nickel and 8% chromium, having a thickness of 1.5 millimeters, these sheets then being embossed, that is to say that they have undulations in two perpendicular directions, said undulations collecting the deformations due to the contraction in the cold.

Figures 11 and 12 show another alternative embodiment of the tank according to the invention. In this variant, the secondary insulation barrier is produced by means of plywood boxes filled with a thermally insulating particulate material, such as perlite: these boxes have been designated by 119 as a whole; each box has a length of one meter and a width of 50 cm; they rest on slats 2 fixed by strands of polymerizable resin on a wall of supporting structure 1. In the description of this variant, all the elements which are found identical to those of the first variant, have been designated by the same reference numbers; this is the case with elements 1 and 2 which have just been mentioned. The boxes 119 rest by their lower plate 119a on the slats 2 and support by their upper plate 119b the strakes invar 4 of the secondary sealing barrier. The strakes 4 are assembled by welding with raised edges on either side of a welding wing 5, as in the first variant. The welding wings 5 are threaded in grooves 6 made in the plate 119b along the median longitudinal axis of the boxes 119.

On the small ribs of the plates 119a of the boxes 119, tenons 120 are arranged, which allow the fixing of the boxes 119 on the supporting structure 1 on the ship; the structure 1 carries, in an alignment direction parallel to the slats 2, retaining members constituted by threaded studs 7, with which are associated fixing plates 8, which bear on the pins 120 and are each locked in position by a nut 9. A stud 7 is provided at each angle of the box 119. In each alignment of studs 7, all the meters, that is to say one stud out of two, are provided to associate the stud 7 with a member tubular 10 intended to constitute an anchoring member for the primary insulation barrier; at the end opposite to the stud 7, the tubular member 10 carries a support flange 11, which comes to jam in a recess 12 of the plate 119b of the box 119. The screw connections on the studs 7 allow, given the length of the threaded part to make up for variations in thickness of the resin tubes on which the slats rest 2. The support flange 11 serves, as in the first variant, to ensure the attachment of a nozzle 16, which passes through the strake 4 by a orifice 15, the endpiece 16 comprising a base 17 which is welded to the strake 4 all around the orifice 15 to ensure sealing. Slats 114 supported in the recesses 12 ensure the closure of the joint areas in line with the retaining members, between two successive anchoring members; these slats restore the continuity of the support wall of the secondary sealing barrier. The joint areas give rise to a padding of thermal insulation before placing the slats 114.

In this variant, the primary insulation barrier consists of foam panels designated by 103 as a whole. These foam panels are rectangular parallelepipeds of 1 meter by 3 meters, which rest on the secondary sealing barrier constituted by the strakes 4 and which are covered, on their face opposite to that which rests on the strakes 4 , by a plywood plate 103c. The longitudinal edges of the plate 103c are arranged parallel to the welding wings 5 to 15 cm from these welding wings. The foam 103a of the panel 103 comprises, on its face which rests on the strakes 4, gutters 127, where the welded wings 105 and the raised edges of the strakes 104 are housed. The panels 103 are arranged with contiguous edges and their edges are glued during installation using a cryogenic adhesive.

One of the angles of each panel 103 is located at the right of a nozzle 16. To accommodate the nozzle 16, there is provided in each panel 103 a well allowing free passage to said nozzle 16. This well opens into a wider recess , where a counter plate 150 is put in place, which is threaded onto the end piece 16 and is brought to bear on the bottom of the abovementioned abutment by a nut 18, which cooperates with the threaded end of the end-piece 16, with the interposition of a washer 22. The plate 22 thus ensures the fixing of the panels 103 of the primary insulating barrier thanks to the anchoring members constituted by the elements 7, 10 and 16. When this fixing is obtained , an insulating resin is injected into the well 123 and the opening where the wafer 150 is located is plugged by means of a plug 151 consisting of a foam zone and a plywood washer.

The primary insulating barrier, produced as indicated above, constitutes a support surface for the primary sealing barrier, support surface, which is perfectly retained relative to the support structure 1. The primary sealing barrier is produced by an assembly of sheets 33 identical to that which has been described in the first alternative embodiment. This assembly is carried out as indicated for the first variant with overlap welds and using metal inserts 28 identical to those of the first variant and positioned like them at the orifices 34 formed on the edges of the sheets 33 and at the right of the zones 35 where the connection of four adjacent sheets 33 takes place.

We will describe below a first embodiment of a connection with the supporting structure in a tank angle. This variant is shown in FIGS. 13 and 14 and the example described assumes that the primary sealing barrier consists of a sheet of embossed cryogenic steel designated by 233 in the drawing. The two panels of the support structure at a right angle are designated by 1 as in FIGS. 1 to 12. The tank angle is produced by means of a plurality of identical cross-pieces designated by 200 as a whole. Each brace 200 is made up of two attachment half-wings 201 and two tank support half-wings 202, a attachment half-wing 201 being in the extension of a support half-wing 202 to constitute a wing of the crosspiece. The two wings of all the crosspieces 200 of the same tank angle are connected along the same edge substantially parallel to that of the tank angle considered. The attachment half-wings 201 of the braces 200 are fixed to the support structure 1 of the ship by bolting. On the side of the tank, each support half-wing 202 carries a wooden wedge 203 covered with a sheet of invar 204; the wedges 203 are pushed towards the edge of the spider 200 by means of two pushing screws 205. The cover sheets 204 come at the level of the surface plates 206 of the elements 207, which constitute the secondary insulation barrier. The connection between the wedge 203 and the element 207 is carried out by means of a plywood slat 208, the edges of which are arranged in appropriate recesses of the wedge 203 and of the element 207. The wedges 203 are bolted on the support half-wings 202 thanks to Ions 209; the secondary sealing barrier constituted by the invar strakes 4 partially covers the batten 208 and each strake 4 is connected to the right of this batten 208 with an invar fur 210 having the same cross section as the strake 4 but a thickness 1.5 millimeters while the strake 4 has a thickness of 0.7 millimeters. The connection of the fur 210 with the strake 4 is effected by overlap welding and the fur 210 covers the bolt heads 209, its end 210a constituting a weld edge on the covering sheet 204 of the wedge 203. All efforts , which are exerted on the secondary sealing barrier, are therefore transferred by the fur 210 on the shims 203 and from there on the cross 200. A connection angle 211 is welded in the angle formed by the two metallic coatings 204 of the two wedges 203. Between the carrying structure 1 and the cross-pieces 200, an insulating foam 212 is put in place, for example by injection. The presence of the separate studs allows relative movement of said cross-pieces, although these these are linked by wedges 203 which have a length of approximately 3 meters and therefore connect several successive cross-pieces 200 to each other.

To ensure the connection of the primary sealing barriers of the two panels at right angles to the condensed tank angle, shims 213 made for example are placed inside the angle formed by the shims 203, made of a material known by the trade name of »Klegecel« then blocks 214 made of plywood, which constitute two layers each formed by two blocks at right angles. The wedges 213 and 214 are held on the support wings 202 of the braces 200 by bolting using bolts 215 screwed into a ferrule 216 and which pass through the fur 210 and the sheet metal 204 and is screwed into the support half-wing 202 of the brace 200; the crossing of the end piece 216 through the secondary sealing barrier takes place in a sealed manner thanks to an annular base 217 of the end piece 216, a base which, when screwed, comes to bear on the sheet of the fur 210 and that we weld on this sheet on all its periphery. On the wooden block 214, there is connected, by means of wood screws 218, a metal angle 219. The stack of wedges 213, 214 and the angle 219 corresponds to the thickness of the elements of the insulation barrier. primary, so that the counterplate plate 220a of this primary insulation barrier which supports the primary sealing barrier is located at the angle 219; this plate 220a is connected to the angle iron 219 by a connection strip 221; the primary sealing barrier 233 is spot welded to the angle iron 219; this welding is carried out by creating orifices at the bottom of the corrugations of the primary sealing barrier 233 and in line with the angle 219 and by welding over the entire periphery of said orifices to ensure sealing at the same time as the mechanical connection.

It can therefore be seen that this structure ensures, in the tank angles, not only the continuity of the sealing of the primary and secondary sealing barriers, but also the transfer of the forces due to contractions, upon cooling, on the supporting structure. by means of the braces 200. The fact that the braces 200 are arranged side by side, with a certain clearance between them, allows a relative movement of these braces during the deformation of the hull of the ship under the effect of the swell .

Figures 15 to 19 show another alternative embodiment of the angles for a tank according to the invention. In this variant, a plurality of secondary brackets 301 is used arranged side by side and having their common edge. These secondary brackets 301 are connected to the two panels at right angles to the carrying structure 1 of the ship by two pairs 302a, 302b and 303a, 303b of tubular members perpendicular to the wings of the secondary bracket 301. The pair of tubular members 302a , 302b does not cross the bracket 301 and these tubular members are welded, on one side to the support structure 1, and on the other, on a wing of the secondary bracket 301, the length of each member is adjusted can be achieved by a sliding sleeve which is welded at the time of implementation. On the contrary, the pair of tubular members 303a, 303b crosses the secondary bracket 301 and presents threaded housings towards the interior of the tank where threaded end pieces 304 are put in place. On each wing of the secondary brackets 301, wooden wedges 305 are put in place, which connect several successive secondary brackets to each other and which are pushed against the edge of the square 301 by pushing screws not shown bearing on flanges 306 welded to the ends of the wings of the brackets 301. When the wooden blocks 305 are suitably pushed towards the edge of the square 301, resin is injected into the space 307 which separates the flange 306 and the block 305. The block 305 is coated with a invar sheet 308 on which flanges 310 are connected which, as in the variant of FIGS. 13 and 14, extend the strakes 4 of the secondary sealing barrier. The furs 310 are welded along their end edge 310a to the invar sheets 308. A connection angle 309 produced by invar ensuring by welding the connection between the two sheets 308, which cover the two shims 305. The end pieces 304 pass through the sheets 308 but have flanges 311, which are welded over their entire periphery to ensure sealing. The secondary sealing barriers were thus connected in the considered angle of the tank.

The two ends 304 have an internally threaded housing and thus allow the fixing of a primary angle 312 which is assembled on the secondary angle 301 by bolts 313 cooperating with the threaded housings of the two ends 304, insulating elements 350 being interposed between angles 312 and feui) ies308. In the primary angle 312, wooden wedges 314 are placed, which play exactly the same role as the wedges 305 in the secondary brackets 301. The wedges 314 are covered with a metallic sheet of invar 315 and are pushed in. position from the edges 316, the gap between the edges 316 and the shims 314 then being filled with injected resin 317. An invar connection angle 318 provides sealing in the angle formed by the two sheets 315. In this exemplary embodiment, the primary sealing barrier is produced by a thick sheet 333 made of invar, sheet metal the end edge of which overlaps the invar sheets 315 and is welded over the entire length of its edge. There was thus made the sealed connection of the two primary sealing barriers 333 in a tank angle.

Taking into account the tensile forces, which relate to the primary and secondary brackets, it has been found that it is advantageous to have the stiffeners in these brackets. On either side of the bolts 313, we therefore put in place, in the primary brackets 312, stiffeners forming in the bracket 312 a wing 319 perpendicular to the edge of the bracket. Similarly, in the plane of the axes of the tubular members 302a, 302b, a stiffener 320 has been placed inside the secondary bracket. The primary and secondary brackets have the same length measured parallel to their edges, the interval between two primary brackets 319 is located to the right of the stiffener 320 of a secondary bracket 301.

We see that the tank structure according to the invention can therefore, without difficulty, give rise to tight corner connections, whether the primary sealing barrier is made with an embossed sheet of cryogenic steel or with a flat sheet made of invar .

Referring to Figure 20, we see that there is shown in perspective a variant for fixing the primary sealing barrier on the primary insulating barrier, whether it is an embodiment of the type Figures 1 to 6 or that of Figures 11 and 12. Figure 20 shows only the primary barrier: the elements of the primary insulation barrier have been designated by 404 and these elements can be indifferently identical to elements 19 or elements 103 previously described. The elements 404 therefore comprise on the side of the interior of the tank a plywood plate 404a and the sheets 33 of the primary sealing barrier are fixed to the plate 404a by a plurality of screws 400 regularly distributed along two adjacent edges of each sheet 33. The screws 400 are ball screws with countersunk heads; the edges of the sheets 33, which receive them, are pierced with orifices of corresponding shape; the screws 400 are screwed into the plywood plates 404a. Each sheet 33 therefore has two adjacent edges screwed as indicated above, while the other two edges overlap the screwed edges of two adjacent sheet and are welded to these two sheets over their entire length as it was previously indicated. The sealing of this assembly of sheets is therefore ensured by the covering of the sheets and their welds; the attachment to the elements 404 of the primary insulating barrier is ensured by the screws 400. There is, of course, a sealing problem in the connection zones of four adjacent sheets; in these connection angles, it has been proposed, for the variant of FIG. 20, to provide sealing by fitting, in the plate 404a of the element 404 concerned, a metal insert 401 strictly identical to the metal inserts 28 previously described, the sheet metal angles being knocked down and coming to weld on the insert 401.

Figure 21 shows a first possible modification of the embodiment of Figure 20. In this modification, we wanted to avoid the introduction of metal inserts in some of the elements of the primary insulation barrier. To do this, the metal inserts of the embodiment of FIG. 20 were replaced by metal sheets 402, which are placed on the plywood plates of the elements of the secondary insulation barrier and maintained on these plates for example at by means of four countersunk-head screws similar to screws 400. The sealing in the connection areas of the angles of four adjacent sheets 33 is then carried out by welding the angles of the four sheets 33 onto the metal sheet 402.

FIG. 22 represents another modification of the embodiment of FIG. 20. According to this modification, the sealing in the connection zone of four sheet metal angles 33 is obtained by arranging a cover plate on the inside of the tank. 403, which covers all of the four angles of the four adjacent sheets, said cover plate being welded over its entire periphery to seal the corner connection.

It is understood that the embodiments described above are in no way limiting and may give rise to any desirable modifications, without departing from the scope of the invention.

Claims (34)

1. A sealing tight and insulating tank, integrated in to the support structure of a vessel, the said tank comprising two successive sealing barriers, the primary one in contact with the product contained in the tank and the secondary disposed between the primary barrier and the support structure of the vessel, the two sealing barriers being alternated with two thermal insulating barriers, the secondary insulating barrier (3) comprising a series of substantially parallelepiped heat insulating components mounted against the support structure of the vessel by retaining de vises rigid with the support structure (1), which cooperate with the mountings disposed on the edge of the components of the secondary insulating barrier, the said components being separated from one another by substantially rectilinear joining zones where the said retaining devices are disposed, the primary insulating barrier also comprising a series of heat insulating components held resting on the secondary sealing barrier, the secondary sealing barrier comprising metal strakes with edges (4) raised towards the interior of the tank, the said strakes comprising thin sheet metal with low dilatation coefficient and being welded edge to edge, by their raised edges, onto the two faces of one welding flange, which is held mechanically on the components of the secondary insulating barrier, characterised by the fact that, on the one hand the primary insulating barrier is held resting on the secondary sealing barrier by means of anchoring devices (7, 10, 11, 16) fixed on the support structure (1) of the vessel, the said anchoring devices passing through the secondary sealing barrier, the sealing of the secondary sealing barrier being held by means of welds, which connect the anchoring devices to the strakes (4) of the secondary sealing barrier, and that, on the other hand, the primary sealing barrier comprises, in a manner itself known, an assembly of metal sheets (33), the edges of which are lap welded, one sheet (33) having a part of its edge in direct contact with the inside of the tank, whilst the other part is in contact with the primary insulating barrier and is mounted on to it, the joins of the corners of a plurality of adjacent metal sheets (33) being carried out by welding.

2. Tank according to claim 1, characterised by the fact that the attachment of one part of the edge of the metal sheets (33) on to the primary insulating barrier is done by localised welds on metal inserts (28) provided on the respective face of the components (19, 103) of the primary insulating barrier.

3. Tank according to claim 1, characterised by the fact that each component (404) of the primary insulating barrier comprises towards the interior of the tank, a plate (404a) of a non-expanded material and that the mounting of one part of the edge of the metal sheets (33) on the primary insulating barrier is made by screws (400) regularly distributed on the part of the edge in question, the said screws being crewed into the said plates (404a).

4. Tank according to one of claims 1 to 3, characterised by the fact that that the welding, which provides the join of a plurality of adjacent metal sheets (33), is made on one metal connection- piece (28,401,402) mounted on a component (19, 103,404) of the primary insulating barrier.

5. Tank according to claim 4, characterised by the fact that the metal connecting piece is a metal insert (28,401).

6. Tank according to claim 4, characterised by the fact that each component (404) of the primary insulating barrier comprises, towards the interior of the tank, a plate (404a) ofa non-expanded material and that the metal connection piece is a metal sheet (402) attached by screwing on to the said plate (404a).

7. Tank according to one of claims 1 to 3, characterised by the fact that the welding which provides the join of a plurality of adjacent metal sheets (33) is made by covering the joining zone of the said metal sheets by a covering plate (403) disposed towards the interior of the tank and welded on the metal sheets (33) on the whole of its periphery.

8. Tank according to one of claims 1 to 7, characterised by the fact that the metal sheets of the primary insulating barrier are flat metal sheets of invar metal sheets having a thickness of between 0,5 and 2 mm.

9. Tank according to one of claims 1 to 7, characterised by the fact that the metal sheets of the primary insulating barrier are corrugated metal sheets in cryogenix steel having a thickness of between 1 and 2 mm, the depth of the corrugations being between 30 and 120 mm.

10. Tank according to on of claims 1 to 9, characterised by the fact that the components of the secondary insulating barrier are panels 3 of alveolar material and those of the primary insulating barrier are caissons 19 divided into compartments internally and filled with a special thermal insulating material.

11. Tank according to one of claims 1 to 9, characterised by the fact that the components of the secondary insulating barrier are caissons (119) filled with a special thermal insulating material and the components of the primary insulating barrierare panels (103) of alveolar material, the large face of which orientated towards the interior of the tank is covered by a plate (103c) of solid non-expanded material.

12. Tank according to one of claims 1 to 11, characterised by the fact that the components (3, 119) of the secondary insulating barrier are all identical rectangular parallelepipeds and that the retainung devices (7) for holding the secondary insulating barrier on the support structure (1) are aligned according to two perpendicular directions, the anchoring devices (7, 10, 11, 16) associated with the primary insulating barrier being disposed regularly in the said alignments.

13. Tank according to one of claims 1 to 12, characterised by the fact that that the retaining devices (7) are threaded pins welded by their base on the support structure (1) of the vessel, that the mountings, which are associated with them, are small plates (8), which rest on, by the screwing of a screw nut (9) on the associated small plate (7), a region of the components (3, 119) of the secondary insulating barrier, and that the anchoring devices comprise tube (10) screwed on certain of the pins (7) capable of comprising the retaining devices.

14. Tank according to claim 13, characterised by the fact that each of the tubes (10) supports, at its most remote end from the support structure (1), on the one hand, a support flange (11) at the level of the secondary insulating barrier and, on the other hand, a joining piece (16) comprising, in the first place, a base (17) which encloses the strake (4) of the secondary sealing barrier between it and the support flange (11) and provides the sealing by welding of its edges on the strakes (4) of the secondary sealing barrier, and, secondly, a threaded part with which a mounting (22, 18) co-operates, which holds the components (19, 103) of the primary insulating barrier in relation to the support structure (1)-

15. Tank according to claim 10 taken alone or in combination with one of claims 12 to 14, characterised by the fact that the panels (3) of the alveolar material have their two large faces covered by a plate (3b, 3c) of rigid non-expanded material, the mounting (8) associated with the retaining devices (7) of the secondary insulating barrier resting on two parallel covering edges of the plates (3b) associated with two adjacent panels (3) and disposed in the vicinity of the support structure (1), the plates (3c) disposed in the vicinity of the secondary insulating barrier comprising parallel channels (6), on which the flanges are engaged (5) serving to weld end to end mmetal strakes (4) of the secondary sealing barrier.

16. Tank according to claims 13 and 15 taken together, characterised by the fact that the channels (6) where the welding flanges (5) are engaged are parallel to one of the alignments of the retaining devices (7).

17. Tank according to one of claims 10, 15 or 16, characterised by the fact that the caissons (19) of the primary insulating barrier have two edges and interior compartments (25) parallel to the welding flanges (5), which project into the the secondary sealing barrier, the said flanges (5) being housed in grooves (27) made on the compartments (25) parallel to the said flanges (5).

18. Tank according to claims 14 and 17 taken together, characterised by the fact that the edges of the components (19) of the primary insulating barrier which are parallel to the welding flanges (5), comprise attached tenons (20) with which the mounting devices (22, 18) associated with linking pieces (16) of the anchoring devices co-operate.

19. Tank according to claims 11 and 12 taken together, characterised by the fact that each caisson (119) of the secondary insulating barrier supports, on its large face (119b) the most remote from the support structure (1), parallel channels (6), in which the flanges (5) serving to weld end to end metal strakes (4) of the secondary insulating barrier are engaged, and, on each of its edges perpendicular to the said channels (6), in the vicinity of the support structure (1), an attached tenon (120) on which the mountings (8, 9) associated with the retaining devices (7) rest, the caisson edges, which do not support any tenon, coming into contact with similar edge of an adjacent caisson (119).

20. Tank according to one of claims 11 or 19 taken alone or in combination with one of claims (13 to 15), characterised by the fact that the panels (103) of the alveolar material of the primary insulating barrier comprise, on their faces in contact with the secondary sealing barrier, grooves (127) where the welding flanges (5) of the secondary sealing barrier are engaged, each panel (103) being stuck by its edges to the adjacent panels (103) and held resting on the secondary sealing barrier by at least one anchoring device (7, 10, 11, 16) the mounting of which (150, 22, 18) rests on the inside recess of a well made in the panel (103) and sealed by a plug (151).

21. Tank according to claim 13 taken together with one of claims (19 or 20), characterised by the fact that each caisson (119) of the secondary insulating barrier is held on the support structure (1) by four retaining devices (7) disposed et each of its corners, two of the four retaining devices, disposed on the same line perpendicular to the tenons (120) of the caisson (119), bearing constituent tubes (10) of anchoring devices.

22. Tank according to one of claims 15 or 19, characterised by the fact that the channels (6), where the welding flanges (5) are engaged, have a straight section in the shape of a T, whilst the welding flanges (5) have a straight section in the form of an L.

23. Tank according to one of claims 1 to 22, characterised by the fact that the components (3, 119) of the secondary insulating barrier rest on the support structure (1) by means of parallel battens (2) resting on projections of polymerisable resin, the battens reconstituting, by discontinuous elements, a defined geometric surface independent of the irregular, spacings of the bearing support (1) in relation to its theoretical surface.

24. Tank according to one of claims 1 to 23, characterised by the fact that the joining zones existing between the components (3, 19, 119) of the insulation barriers due to the presence of the retaining devices (7) and anchoring devices (10, 11, 16) are filled with insulating material after tightening the mountings and closing form behind the metal sheets (4, 33) which constitute the sealing barriers by battens (14, 24, 114) supported in the appropriate inside recess made on the edges of the components (3, 19, 119) of the respective insulation barriers.

25. Tank according to one of claims 2 or 5, taken alone or in combination with one of claims (8 to 24), characterised by the fact that the metal inserts (28) of the components (19, 103) of the primary insulation barrier are tablets put into place and held in perforations made in a respective shape in the plate (19b) of the component (19) of the primary insulating barrier which supports the primary sealing barrier.

26. Tank according to one of claims 1 to 25, characterised by the fact that the tank corners are made by means of a plurality of identical cross pieces (200), disposed side by side and each consisting of two semi-wings for attachment (201) and two semi-wing tank supports (202), a semi-wings for attachment (201) being in the extension of a semi-wing support (202) to constitute a crosspiece flange (200), the two wings of all the crosspieces (200), by the same corner joining together according to the same edge substantially parallel to that of the corner of the tank in question, the semi-wings for attachment (201) of the crosspieces (200) being mounted on the support structure (1) of the vessel and the semi-wing supports (202) of the crosspieces being integral with the metal strakes (4) of the secondary sealing barrier.

27. Tank according to claim 26, characterised by the fact that in the corner of the of the semi-wing supports (202) which is orientated towards the tank, the crosspieces (200) of the same tank corner support, on each of the semi-wing supports (202) of the crosspiece, secondary wedges (203) held on a plurality of adjacent and covering crosspieces, towards where the tank is located, a metal sheet of the same metal as that of the strakes (4) of the secondary sealing barrier, which are substantially in the same plane and are soldered on to them.

28. Tank according to claim 27, characterised by the fact that that one linking corner member (211) is welded on to the metal sheets, which cover the two adjacent secondary wedges (203) of a corner of the tank.

29. Tank according to one of claims 21 or 28, characterised by the fact that primary wedges (213, 214) are disposed in the corner of the secondary wedges (203) and mounted on the crosspieces (200) by means of attachment devices (215, 216, 217), which pass through the secondary sealing barrier or its extension in a sealed manner, the said primary wedges (213, 214) supporting metal corner member (219) on which the primary sealing barrier (233) is welded.

30. Tank according to one of claims 1 to 25, characterised by the fact that the corners of the tank are made by means of a plurality identical secondary corner members (301) disposed side by side and joining together according to the same edge substantially parallel to that of the tank corner in question, the secondary corner members (301) each being supported by four tubular devices (302a, 302b, 303a, 303b) disposed two by two in the same plane perpendicular to the said edge, the pairs (303a, 303b) of tubular devices extending towards the tank to support a plurality of identical primary corner members (312), disposed side by side and joining together according to the same edge substantially parallel to that of the secondary corner members (301), primary (312) and secondary members (301) supporting wedges (314, 305) covered by a metal sheet (315, 308) the same type as that which comprises the respective sealing barrier, the said sheet being welded onto the said barrier.

31. Tank according to claim 30, characterised by the fact that the primary (312) and secondary (301) corner members are each provided with two wedges (314, 305) at right angles the metal covering sheets (315, 308) of which are covered, in the corner which they form, by a welded linking ocrner bracket (318, 309).

32. Tank according to one of claims 30 or 31, characterised by the fact that the tubular devices (303a, 303b), which support the primary corner members (312), pass through the secondary sealing barrier or its extension in a sealed manner, two reinforcements at an angle (319) being arranged in each primary corner member (312), on both sides of the tubular devices (303a, 303b), which support it.

33. Tank according to one of claims 30 to 32, characterised by the fact that the secondary corner members (301) comprise a reinforcement at an angle (320) at right angles with each pair of tubular devices (302a, 302b), which is not extended towards a primary corner member (312).

34. Tank according to one of claims 30 to 33, characterised by the fact that the primary (312) and secondary corner members (301) have the same length, measured parallel to their edge, and that the separation plane of two primary adjacent corner members ist at right angles to a secondary reinforcement at an angle (320).

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