JPH0417303B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a leak-free, thermally insulated tank for the maritime transport of liquefied gases, in particular for the transport of natural liquefied gases with a high methane content.

French patents No. 1438330, No. 2105710, No. 2146612 and No. 2413260 already provide for the construction of leak-proof insulated tanks, which are integrated into the support structure of the ship and have two successive sealing barriers, i.e. formed by a first barrier in contact with the gas and a second barrier arranged between this first barrier and the load-bearing structure of the ship, these two sealing barriers being called insulating barriers. Alternating with insulating layers. The sea transport of liquefied gases, which takes place at extremely low temperatures, is carried out by the conventionally proposed system at a evaporation rate per voyage day that is reduced to a low level that is considered sufficient from an economic point of view. Generally allowed evaporation per day of transportation is
It is 0.18% by weight. This evaporated gas is therefore used in the transport ship's propulsion engine. However, it is anticipated that propulsion of transport vessels may be done more economically than by burning expensive fuels such as methane-rich gas. From this point of view it is encouraged to minimize the evaporation of the transported liquefied gases, which means that the thermal insulation of the corresponding tanks must be improved.

In the past, some tank constructions have been proposed in which insulation is achieved using plastic foam panels (see FR 2413260 in this regard). Plastic foam has very good thermal insulating properties, so if the thickness used is increased even slightly, it can reduce heat exchange during transportation and therefore also reduce evaporation losses. can. However, the essential disadvantage of using plastic foam is its very high price. While the use of smaller plastic thicknesses is economically acceptable, the increased amount of foam required is very costly. There is therefore a temptation to return to the insulating barriers proposed by French patents 21057110 and 2146612.
Such barriers are formed by parallelepiped caissons filled with thermally insulating material. Unfortunately, as the thickness of the insulating caisson increases in the insulation barrier, the caisson wall and the load-bearing cross members it contains are forced to withstand the hydrostatic pressures generated by the liquid contained within the tank. The risk of buckling occurring with transverse members arranged perpendicular to the tank sealing barrier is increased. If it is desired to increase the buckling resistance of the caissons and the load-bearing transverse members therein, it becomes necessary to increase the cross-section of said transverse members;
This considerably increases the thermal bridge formed between the liquefied gas and the ship's load support structure. When using such a caisson structure, one therefore faces the problem that it becomes almost impossible to increase the thickness of the tank insulation barrier, which limits the efficiency of the insulation. Furthermore, as the thickness of the caisson increases, gaseous convection occurs due to the increased temperature gradient between two successive walls, and such convection is difficult to achieve if good thermal insulation is desired. It turned out to be very disadvantageous.

Conventionally, therefore, from the point of view of the structures proposed for producing such tanks, the problem has arisen that improvements in thermal insulation require a considerable increase in price. It is an object of the present invention to provide a new construction of a tank, which makes it possible to make a leak-free, thermally insulated tank, reducing evaporation losses without increasing the cost of the transport vessel. According to the invention, in order to avoid an increase in costs, the caisson is filled with thermal insulation material and an insulation is used which avoids problems arising due to the thickness of the thermal insulation, i.e. two A second layer is added in the superimposed layer.
The casing of each layer is arranged parallel to only one side of the caisson, and the cross members of the two layers intersect, so that a thermal bridge It has been proposed to provide a cross member in which the load-bearing cross member of these two layers only occurs at the interlocking portions. As far as the mechanism is concerned, it can be seen that the provision of load-bearing cross members in the two layers makes it possible to counteract the hydrostatic and dynamic pressures acting on the tank wall. At the same time, it can be seen that heat loss occurs only in the fastened portions of the cross members, and since the thickness of the cross members is not as large as in conventional constructions, this heat loss is also significantly reduced. The thickness of the second insulating barrier can therefore be doubled without mechanical drawbacks, and since the two layers of this second insulating barrier are separated from each other, the interior of the caisson is no convection occurs. Finally, the cost of a device with a single-thickness second insulating barrier according to the invention is not significantly higher than a device with a unit-thickness second insulating barrier formed by plastic foam. No. The invention therefore makes it possible to improve the insulation properties of leak-free, thermally insulated tanks integrated into the load-bearing structure of ships without substantially increasing costs. Therefore, the evaporation rate per day of transportation for natural liquefied gas with a large methane content can be reduced to 0.12% by weight.

It is therefore an object of the present invention to create a new industrial product consisting of a leak-free isothermal tank integrated into the load-bearing structure of a ship, said tank having two successive sealing barriers, the first one being , that is, the first
a barrier is in contact with the product contained within the tank, and another one, namely a second barrier, is arranged between said first barrier and the load-bearing structure of the ship, these two sealing barriers being in contact with the product contained in the tank; alternating with two thermally insulated barriers, said first and second sealing barriers being formed by metal strips having edges rising towards the inside of the tank; The welding flange is formed by a thin plate with a low coefficient of thermal expansion and whose rising edges are welded together on the two faces of a welding flange which is mechanically held in place on the underlying insulating barrier member. two insulating barriers are formed by a set of substantially parallelepiped insulating members, the insulating members being secured to the ship's support structure by means of retaining members secured to the ship's load-bearing structure; A retaining member cooperates with a fastening device disposed on the edge of the insulating member of the second insulating barrier, said insulating member being interconnected by a substantially straight connecting portion in which said fastening device is disposed. separated, and the first insulating barrier further
a set of insulating members, the insulating members being held in a supported position on the second sealing barrier by a clamping device fixed to the load-bearing structure of the ship, the clamping device being secured to the second sealing barrier; and wherein the sealing of the second sealing barrier is maintained by welding the clamping device to the strip of the second sealing barrier, the second insulating barrier comprising two superposed formed by layers of insulating material, the first layer being the second layer.
a second layer disposed directly below the sealing barrier and between said first layer and the ship's load-bearing structure, each of the two layers of the second insulating barrier having mutually parallel internal load-bearing laterals; formed by an insulating caisson having members, the arrangement of the transverse members of the caisson in two layers being such that an angle of preferably approximately 90 degrees, non-zero, is formed between said layers; a first layer of insulation barrier retaining device is secured to the ship's load-bearing structure through the second layer of the second insulation barrier; are arranged differently from one another, the caissons constituting the second insulation barrier and the first insulation barrier have walls and load-bearing cross members made of plywood, and the load-bearing of one caisson The transverse member is parallel to one side of the caisson, while
To provide an industrial product consisting of a leak-tight insulating tank, characterized in that the non-load-bearing cross members are arranged at right angles to said load-bearing cross members and are formed of thermally insulating plastic foam. be.

In a preferred embodiment, the first
The retaining member of the layer has an extension extending through the second sealing barrier and forming a fastening device to hold the insulation member of the first insulating barrier in place; The extension of the retention device of the first layer of the insulating barrier is connected in a leaktight manner to the second sealing barrier by a circumferential weld.

each retaining member of one layer of the second insulating barrier is adapted to cooperate with four fastening devices preferably arranged at adjacent corners of the four insulating members of that layer;
The fastening device for the insulation member of the second insulation barrier is a cleat located near the corner of the undulating portion of the caisson wall, between which a connecting portion is formed, the fastening device for the insulation member of the first or second insulation barrier. all have parallel connecting parts, members of one and the same insulating layer touch each other along their edges that do not form a connecting part,
a retaining device for a first layer of heat insulating member of a second insulating barrier;
The fastening device of the insulation element of the first insulating barrier consists of a deformable element that allows for elastic gripping.

The caissons of the two layers of the second insulation barrier preferably consist of internal non-load-bearing cross members arranged between load-bearing cross members, and the caisson of the first insulation barrier comprises internal load-bearing cross members parallel to each other. a non-load-bearing cross member disposed between the load-bearing cross members, the caisson of the first insulating barrier having a linear groove on its side facing the second sealing barrier; is cut opposite the load-bearing cross-member and extends into the load-bearing cross-member and is adapted to fit a weld flange projecting onto the second sealing barrier;
The insulation barrier caisson and the caisson of the first layer of the second insulation barrier have grooves on their sides located below the sealing barrier perpendicular to the connecting part, each groove having a T
having a cylindrical cross section and surrounding welded flanges on both sides, to which a strip is welded by a rising edge, the insulation member of the first insulation barrier and the insulation member of the second insulation barrier are caisson. , these caissons are filled with a granular material that has good thermal insulation properties.

The caissons of the second layer of the second insulating barrier are in known manner over strips positioned on the ship's load-bearing structure by the insertion of extruded polymerizable material.
The strips are supported by associated retaining devices, and these strips are clearly defined by the discontinuous members, regardless of any accidental deviation of the load-bearing structure from its theoretical surface. It is designed to form a geometric surface.

It is clear that the first and second sealing barriers need to be supported continuously by the underlying insulating barrier, so that the connecting part is provided with support for the metal strip forming the sealing barrier. It is necessary to prevent the occurrence of parts that cannot be avoided. The reason for this is that the retaining and fastening device, which must be filled with insulating material after closing by inserting a block in or opposite the connecting part after the sheet which tightens the fastening device and forms a sealing barrier, Because there is.

According to the invention, each retaining device of the first layer of the second insulating barrier passes through the second layer in its central part and, within the caisson, an insulating sleeve is arranged between two load-bearing cross members of the caisson. surrounded by a retaining device for the first layer of the second insulating barrier preferably consisting of a threaded rod, which rod is screwed at its base into a threaded socket welded to the load-bearing structure of the ship; said rod carries a stirrup by tightening a nut on its head which bears against the cleat of the caisson of the first layer of the second insulating barrier, to said stirrup a plate is welded at the level of the second sealing barrier; , and having a threaded hole, an extension formed by the collar, and a bolt threaded into the threaded hole and passing through the second sealing barrier, the bolt being screwed into the head of the first sealing barrier. It has a plate that contacts the cleat of the insulating barrier caisson.

It is further object of the invention to provide a novel industrial product constituted by a liquefied gas transport vessel, comprising at least one leak-tight insulated tank integrated into its load-bearing structure and having characteristics as mentioned above. The aim is to provide products with

BRIEF DESCRIPTION OF THE DRAWINGS To facilitate understanding of the purpose of the invention, preferred embodiments of the invention will be described with reference to the accompanying drawings.

As is clear from the figure, 1 represents the load-bearing structure of the ship, ie the double skin or double partition supporting the walls of the tank according to the invention.
Due to manufacturing tolerances, the sides of the load-bearing structure 1 are locally deformed, which proves to be a poor fit when forming a tank according to the invention. In the known method, a strip of plywood 2 is placed on the side 1;
The plywood is brought into contact with the extrusion polymerizable resin 3, and the position of the strip 2 is adjusted so that it continuously defines a theoretical surface regardless of the configuration of the side 1. be done.

Above the strip 2 a member of a second layer of a second insulating barrier is positioned. These parts are 4
It is represented by. Each member is formed as a parallelepiped caisson of plywood measuring 1.2 meters by 1 meter. This caisson has internal cross members 5, all of which are parallel to the long sides of the caisson. Said cross member 5 is inserted between the two large sides of the caisson, one of said large sides resting on the strip 2. A non-load supporting transverse member 6 is placed between the load supporting transverse members 5, but this is merely to maintain the relative position of the transverse members 5, and this non-load supporting transverse member 6 is formed by plastic foam. The thickness of each caisson 4 is 25 centimeters. Each caisson has five load-bearing transverse members 5
and three non-load supporting transverse members 6. An opening 7 is formed in the central part of each large side of the caisson, and this opening 7 has a circular shape. Opposed to this opening is a sleeve 6a, which is a block of plastic foam and serves as a non-load-bearing cross member between the two load-bearing cross members 5. Caisson 4 is installed in sleeve 6a.
A vertical cylindrical hole is drilled into the large side of the The large side of the caisson 4 rests on the two ends 8 of this side on a strip 2 projecting from the side wall of the caisson, and at each corner of the caisson there is a strip 2 on said projecting part with a thickness equal to that thickness. A cleat 9 is provided. These cleats (fasteners) 9 form a device for fixing the caissons.

Said fastening device 9 cooperates with a retaining device formed by a trunnion 10 welded to the ship's load-bearing structure, said trunnion 10 having a threaded end 10.
a, and is adapted to cooperate with a nut 11 which rests on a square plate 12. By positioning the four caissons 4 so that their corners are close to the trunnions 10, the four cleats 9 near the trunnions are held in place by the plates 12 associated with the trunnions. If you tighten nut 11, plate 12
contacts on the four cleats 9, so that the four caissons 4 adjacent to the trunnion 10 in question are held in place. It can thus be seen that the caisson 4 is held in place by the plates 12 at each of its four corners. The caissons 4 abut each other along the sides perpendicular to the line of alignment of the trunnions 10 and in the vertical direction, and the caissons 4 are joined by connecting parts where the cleats 9 and the retaining devices 10, 11, 12 are located. It is placed in the corner.
After all the retaining devices have been screwed on, the connecting part is connected to the block 13 made of plastic material.
The block has a longitudinal gap which allows insertion of a resilient gripping member into the connecting part. A portion of the connecting portion which is not filled with block 13 is filled with glass wool. The block 13 is a vertical channel 13
a to allow nitrogen to circulate through the second layer of the second insulating barrier.

The second insulating barrier has a first layer formed by each caisson, generally designated 14, over the second layer just mentioned. The set of caisson 14 rests directly on the set of caissons 4. Each caisson 14 is formed by a parallelepiped box made of plywood, said box having a thickness of 20 centimeters and a large side of the same dimensions as the large side of the caisson 4. Inside each caisson 14 are seven load-bearing cross members 1 parallel to the small sides.
5 are equally spaced apart, and three non-load-bearing cross members 16 are arranged, the load-bearing cross members 15 being plywood sheets inserted between the large sides of the caissons 14. The non-load-bearing cross member 16 is made of plastic foam and has the same function as the cross member 6 described above. Each caisson 1
4 has a cleat 17 at each of the four corners on its smaller side, which cleats project from the sides of the caisson. The large side of the caisson 14 located inside the tank, i.e. the side opposite to the caisson 4, has two grooves 1 parallel to the large side of the caisson.
It has 8. These grooves are formed in the thickness of the large side of the caisson and have a T-shaped cross section. Positioned within said groove 18 is a welding flange 19 formed by a strip of umber, said strip being bent at right angles so as to have an L-shaped cross section.

The retention device for this first layer of the second insulating barrier is the rod 20
The base of the rod is screwed into a socket 21 welded to the ship's load-bearing structure. Said socket 21 is positioned exactly opposite the hole 7 of the caisson 4. stick 20
is passed through the caisson 4 and through the hole 7 and the hole in the sleeve 6a, and after this rod has been positioned, a glass wool packing is placed around the rod 20 filling the hole 6a. When the rod 20 is screwed into the socket 21, at its end opposite the socket it engages a stirrup 22, the edge of which is connected to four adjacent caissons 14 positioned around one and the same rod 20. The four adjacent cleats 17 can be touched and seated on the four adjacent cleats 17. The tightening of the stirrups on the four cleats 17 is carried out by means of nuts 23 cooperating with the corresponding threaded ends of the rods 20, with "Belleville" washers 24 inserted between said nuts 23 and the stirrups 22. It is placed.

After the holding device 22 has been tightened to the fixing member 17, a plate 25 is inserted between the sides of the stirrup 22.
are arranged so that their height corresponds exactly to the height of the large side of the vessel 14. The plate 25 has a screw hole 25a at its center. The connecting part is provided between the rods 20 with an insertion block 26 made of plastic material, which block has a longitudinal slot and is inserted into the connecting part in an elastically compressed state and then It is adapted to be retained therein by the elastic blocking action of. The block 26 has a longitudinal groove 26a having the same function as the groove 13a of the block 13. The part of the connecting part of this first layer which is not occupied by the block 26 of insulating plastic material is advantageously filled with glass wool to improve the insulation.

A second sealing barrier is positioned above the second layer of the second insulation barrier and is formed by a raised edged umber strip 27. These strips are arranged between two successive flanges 19 and have a width of 50 centimeters. A continuous weld is made on both sides of the flange 19 to ensure a positive seal. Flange 1
9 holds the second sealing barrier above the caisson 14. The bearing surface of the second sealing barrier is continuous even when facing the connection between the caissons 14 due to the provision of the blocks 26 and plates 25. Block 2 faces the groove 18 of the caisson 14.
6 has a recess 26b through which the flange 19 can pass freely. If a second sealing barrier is formed in this way, the pressure between the load-bearing structure 1 and said sealing barrier is reduced. The thickness of said strip 27 is very small (approximately 0.5 mm) and therefore presents a small recess for each hole 25a formed in the plate 25. The strip 27 is therefore provided with opposing holes 25a positioned in this way, into which a threaded collar 28 engages, which collar 28 is fitted around its circumference. The flange 28a is screwed into the screw hole 25a until it contacts the corresponding strip 27. Manufacturing of the tank then continues by welding around flange 28a, sealing the second sealing barrier and positioning the first insulation barrier.

The first insulating barrier is formed by a caisson 29, which is held in place by a fastening device fixed in the collar 28.

Each caisson 29 is a parallelepiped box made of plywood, and the thickness of the box is 20 centimeters. Large side dimensions are caisson 4, 14
equal to the dimensions of Seven load-bearing cross members 30 are arranged in the caisson 29, the relative position of which is maintained by non-load-bearing cross members 31 formed by plastic foam. On the side of the caisson, corresponding to the small side of the large surface, a cleat 32 is arranged along the edge located towards the inside of the tank, the cleat 32 extending over the entire edge and having dowels at both ends thereof. It has 33. Caisson 2 located towards the inside of the tank
The large side of 9 projects above the cleat 32, leaving said dowel 33 free, and this side further has a groove 34, which groove is perpendicular to the cleat 32 and projects above the cleat 32. Formed in thickness. This groove has a T-shaped cross section and the groove 18
The welding flange 35, which is similar to the flange 19, is positioned therein. Caisson 2 located on the side opposite to the side carrying the groove 34
The large side of 9 also has a groove 35 which is formed oppositely in the cross member 30. Said groove 35 is adapted to mate with the raised edge of the strip associated with the weld flange 19. In practice, said welding flange 19 projects towards the inside of the tank relative to the face of the second sealing barrier and thus enters a groove 35 for the caisson 29;
It must be adapted to exert tactile pressure against the second sealing barrier.

Retention of the caisson 29 in position on the second sealing barrier is carried out by means of a fastening device, which is connected to the head 3
8 and a rectangular plate 37, which has four dowels 3 of four adjacent caissons 29 arranged around one and the same collar 28.
It is designed to apply tactile pressure on top of 3. bolt 36
is screwed into the collar 28 and the square plate 37
Positioned within the dowel, a "Belleville" washer is inserted between the square plate 37 and the bolt head 38. The load-bearing structure of the first insulating barrier formed by the caissons 29 can then be fixed as a whole.

Holding the two layer sets of the second insulating barrier in place is done by the resilient grip of the pressure of the "Belville" washer 24, and similarly holding the first insulating barrier in place is done by the "Belville" washer 24. ``This is done by elastic gripping due to the pressure of the washer 39. It is thus possible to compensate for the shrinkage of the caisson wood due to the permanent encroachment of nitrogen that occurs during operation in the first and second insulation barriers.

A square block 40 is positioned opposite the fastening devices 36, 37, 38, 39 and is adapted to close the hole opposite the dowel 33. In this way, the large surface of the caisson 29 with the groove 34 becomes a continuous surface, due to the provision of said block 40, on which surface the first sealing barrier of the tank contacts. This first sealing barrier is formed by an umber strip 41. This strip is the same as the strip 27 described above. The strip 41 is welded at its rising edges to both sides of a welding flange 35 positioned in the groove 34.

The aforementioned caissons 4, 14, 29 are filled with a granular thermal insulation material such as perlite.

It can be seen that with the structure as described above, a tank with very excellent thermal insulation properties can be obtained. As a practical matter, the evaporation rate of natural liquefied gas with a high methane content can be reduced from 0.18% to 0.12% by weight per day of transportation.

The price of such a structure is not much greater than a structure using plastic foam, taking into account the price of the plastic foam. Since an insulating layer formed by a foam is not used, the increase in labor cost due to the use of two caisson layers forming the second insulating barrier can be suppressed.

It should be understood that the above embodiments are not meant to be limiting, and that the present invention can be modified in various ways without departing from the scope of the claims.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the various components constituting a leak-tight insulating tank according to the invention; FIG. 2 is a plan view showing the caisson of the second layer of the second insulating barrier, with a portion of the top of the caisson cut away; thing; Figure 3 is the second
FIG. 4 is a plan view showing a caisson of the first layer of insulation barrier, with a portion of the top of the caisson cut away; FIG. FIG. 5 is a detailed sectional view taken along the line V--V of FIG. 4;
FIG. 6 is a detailed perspective view showing the fixed state of the second layer caisson of the second insulation barrier; FIG. 7 is a detailed perspective view showing the fixed state of the first layer caisson of the second insulation barrier;
Figure 8 is a detailed perspective view showing the fixation of the caisson of the first insulation barrier; Figure 9 is a cross-sectional view perpendicular to the load-bearing structure of the ship, showing the retention of the first layer of the second insulation barrier to the caisson; Indicates the part facing the device,
The retaining device extends into a fastening device of the first insulation barrier to the caisson. In the figure, 4...caisson; 5...lateral member;
6... Non-load supporting lateral member; 9... Cleat; 14
...caisson; 20...rod; 21...socket;
26...Insert block; 29...Caisson; 30
……Horizontal member; 31…Non-load supporting lateral member; 35…
...welded flange.

Claims (1)

Claims: 1. A leak-proof insulated tank integrated within the load-bearing structure of a ship, said tank having two successive sealing barriers, one of which, the first sealing barrier, is located inside the tank. a second sealing barrier is arranged between said first sealing barrier and a load-bearing structure of the ship, these two sealing barriers alternating with two thermally insulating barriers; , wherein the first and second sealing barriers are formed by metal strips having edges rising toward the inside of the tank, and the strips are formed by a thin plate having a small coefficient of thermal expansion. , and the rising edges of which are welded together on opposite sides of a welding flange mechanically retained on the underlying insulation barrier member, the second insulation barrier being a set of substantially parallelepiped insulation members; wherein the insulation member is secured to the load supporting structure by means of retaining devices secured to the ship's load supporting structure, each retaining device being connected to a second
cooperating with fastening devices arranged at the edges of the insulation elements of the insulating barrier, said insulation elements being separated from each other by a substantially straight connecting section in which said fastening devices are arranged; the first insulating barrier further comprising a set of insulating members, the insulating members being held in tactile contact over the second sealing barrier by a clamping device secured to the ship's load-bearing structure; In a tank, the tightening device passes through a second sealing barrier and the sealing of the second sealing barrier is maintained by welding the tightening device to a strip of the second sealing barrier, said second insulation barrier is formed by two superimposed layers of insulation material 4, 14;
A first layer 14 is disposed directly below the second sealing barrier 27 and a second layer 4 is disposed between said first layer 14 and the ship's load-bearing structure 1, and a second layer 4 of the second insulating barrier Insulating caissons 4, 1 each of two layers 4, 14 having mutually parallel internal load-bearing cross members 5, 15
4, formed by two layers of caisson 4,1
The arrangement of the horizontal members 5, 15 of 4 is similar to that of the horizontal members 5, 1.
5, the retaining devices 20-24 of the first layer 14 of said second insulating barrier are adapted to form an angle of not 0 degrees, preferably close to 90 degrees, between said second insulating barriers. is fixed to the ship's load-bearing structure 1 through a second layer 4 of the second insulation barrier, the connecting portions of the first and second layers of the second insulation barrier being staggered; The caissons 4, 14, 29 constituting the barrier and the first insulating barrier have walls and load-bearing transverse members 5, 15, 30 made of plywood.
, the load-bearing cross members of one caisson are parallel to one side of the caisson, while the non-load-bearing cross members 6, 16, 31 are parallel to said load-bearing cross members 5, 15, 30. A leak-tight insulating tank characterized in that it is arranged at right angles to the tank and is formed by a thermally insulating plastic foam. 2. In the tank according to claim 1, the holding device 20-2 for the first layer of the second insulating barrier
4 each have an extension portion 25, 28, 36,
The extension passes through the second sealing barrier 27 and forms the tightening device, and the extension part passes through the second sealing barrier 27 and forms the said tightening device, and the insulation member 2 of the first insulation barrier
A leak-proof insulated tank designed to hold the 9 in place. 3. In the tank according to claim 2, the holding device 20-2 for the first layer of the second insulating barrier
4 extensions 25, 28, 36 are leak-tightly connected to the second sealing barrier by circumferential welding. 4. A tank according to any one of claims 1 to 3, in which each retaining member 12, 22 of one layer of the second insulating barrier is one of the four insulating members 4 of that layer. . 5. A tank according to claim 4, in which the fastening device of the heat insulating member of the second insulating barrier is a cleat 9, 17 located near the recessed corner of the wall of the caisson 4, 14. A leak-proof insulated tank having a connecting portion formed between the cleats. 6. In the tank according to any one of claims 1 to 5, the first or second insulation barrier members 4, 14, 29 all have parallel connection parts, A leak-tight insulating tank in which members of the same insulating layer touch each other along their edges where they do not form a joint. 7. In the tank according to any one of claims 1 to 6, the holding device 20 for the heat insulating member 14 of the first layer of the second insulation barrier
24 and the tightening devices 36 to 39 of the insulating member 29 of the first insulating barrier have deformable members ensuring elastic gripping. 8. A tank according to any one of claims 1 to 7, in which the two layers of caissons 4, 14 of the second insulating barrier are arranged between the load-bearing transverse members 5, 15. A leak-tight insulated tank having internal non-load supporting cross members 6,16. 9. A tank according to any one of claims 1 to 8, in which the caissons 29 of the first insulating barrier include load-bearing transverse members 30, all parallel to one another; A leak-tight insulating tank having a non-load supporting cross member 31 disposed therein. 10 In the tank according to claim 1 or 9, the caisson 29 of the first insulation barrier
has a linear groove 35 on its side opposite the second sealing barrier, the groove being cut so as to face and extend into the load-bearing cross member 30; A leak-tight insulating tank adapted to accommodate a welding flange 19 projecting onto a sealing barrier 27. 11. In the tank according to claims 1 and 6, the caisson 29 of the first insulation barrier
and the caissons 14 of the first layer of the second insulation barrier have grooves (18 or 34) on their sides located below the sealing barrier at right angles to the connecting part, each groove having a T-shaped cross section. and a welding flange (19
or 35), and a leak-tight insulating tank having a strip welded to it by a rising edge (27 or 41) on one side of said welding flange. 12. In the tank according to any one of claims 1 to 11, the first
Insulating barrier and second insulating barrier heat insulating members 4,1
4,29 is a leak-free insulating tank which is a caisson filled with granular material having good thermal insulation properties. 13. In the tank described in any one of claims 1 to 12,
The caissons 4 of the second layer of the second insulating barrier are inserted with associated retaining devices 10, 11, 12 onto the strips 2 placed on the load-bearing structure 1 of the ship, a member of polymerizable resin. The leak-free structure is supported in a fixed position such that these strips 2 form a geometric surface defined by the discontinuous elements irrespective of any accidental deflection of the load-bearing structure 1 with respect to the theoretical surface. No insulation tank. 14. In the tank according to any one of claims 1 to 13, the holding devices 10-12, 20-24 and the tightening device 36
-39, the insulation barrier members 4, 14,
29, which is filled with insulating material after tightening the fastening device and positioned behind the sheets 27, 41 forming a sealing barrier, in or opposite the connecting part. Leak-free insulating tank closed by blocks 13, 26, 40. 15. In the tank according to claim 1, each retaining device of the member 14 of the first layer of the second insulation barrier penetrates into the central part of the caisson 4 of the second layer, while within the caisson 4 is the caisson 2
A leak-tight insulating tank surrounded by an insulating sleeve 6a arranged between two load-bearing cross members 5. 16. A tank according to claim 15, in which the retention device of the first layer of the second insulating barrier is attached to a rod 20 screwed at its base into a threaded socket 21 welded to the load-bearing structure 1 of the ship. The stirrup 22 is thus constructed, and the head of said rod 20 rests against the cleat 17 of the caisson 14 of the first layer of the second insulation barrier by tightening the nut 23.
A plate 25 is welded to the stirrup at the level of the second sealing barrier 27 and has a screw hole 25a.
an extension formed by a collar 28 and a bolt 36 is screwed into the screw hole 25a by passing through the second sealing barrier, and the head of the bolt is screwed into the first insulating barrier by tightening the bolt. A leak-tight insulating tank carrying a contacting plate 37 on the cleat 32 of the caisson 29 of. 17. A transport ship for natural liquefied gas with a large methane content, which has at least one of the tanks described in any one of claims 1 to 16.