FR3110951A1 - ANCHORING DEVICE INTENDED TO RETAIN INSULATING BLOCKS - Google Patents

Abstract

An anchoring device intended to retain insulating blocks against a load-bearing wall comprises a clamping assembly (30) comprising a lower plate (31), an upper plate (32) parallel to the lower plate, and an abutment piece (33 ) rigid defining a minimum spacing between the lower plate and the upper plate. The spacing member further comprises an elastically compressible member (39) tending to maintain the lower plate and the upper plate (32) in a separated position, the connecting member defining a maximum spacing between the lower plate and the upper in the spaced apart position, said maximum spacing being greater than said minimum spacing, the elastically compressible member (39) being configured to be elastically compressed up to said abutment position of the lower and upper plates (31, 32) against the part of stop (33) in response to a force tending to bring the upper plate closer to the lower plate. Fig. 3

Description

ANCHORAGE DEVICE INTENDED TO RETAIN INSULATING BLOCKS

The invention relates to the field of sealed and thermally insulating tanks integrated into a supporting structure to contain a cold fluid, in particular to membrane tanks to contain liquefied gases, and in particular to mechanical anchoring devices that can be used in such a tank.

Sealed and thermally insulating tanks can be used in different industries to store cold products. For example, in the field of energy, liquefied natural gas (LNG) is a liquid with a high methane content that can be stored at atmospheric pressure at approximately -163°C in onshore storage tanks or in onboard tanks. in floating structures. Liquefied Petroleum Gas (LPG) can be stored at a temperature between -50°C and 0°C.

In the case of a floating structure, the tank may be intended for the transport of liquefied gas or to receive liquefied gas used as fuel for the propulsion of the floating structure.

We know, for example from documents WO-A-2014096600 and WO-A-2019110894, a sealed and thermally insulating tank for storing liquefied natural gas arranged in a supporting structure and whose walls have a multilayer structure, namely 'exterior to the interior of the tank, a secondary thermally insulating barrier anchored against the load-bearing structure, a secondary sealing membrane which is supported by the secondary thermally insulating barrier, a primary thermally insulating barrier which is supported by the secondary sealing and a primary sealing membrane which is supported by the primary thermally insulating barrier and which is intended to be in contact with the liquefied natural gas stored in the tank.

Each thermal insulation barrier, primary and secondary, comprises a set of modular insulating blocks, respectively primary and secondary, of generally parallelepiped shape which are juxtaposed and which thus form a support surface for a respective sealing membrane. The insulating blocks are anchored to the supporting structure by means of anchoring devices which are fixed to the supporting structure and which are positioned at the corners of the primary and secondary insulating blocks. Each anchoring device thus cooperates with the corners of four adjacent secondary insulating blocks and with the corners of four adjacent primary insulating blocks in order to retain them against the load-bearing structure.

Certain aspects of the invention start from the observation that the walls of the tank can undergo significant and localized compressive stresses due to the phenomena of sloshing of the liquids contained in the tanks. However, the anchoring devices are made with components that are generally stiffer than the insulating blocks in order to be able to reliably anchor the thermally insulating barriers while having a limited footprint. These differences in stiffness lead to a risk of creating defects in the flatness of a thermally insulating barrier in response to compressive stresses, in particular when the thermally insulating barrier is essentially made of polymer foam. These flatness defects can cause stress concentrations at the anchoring devices which would be detrimental to the integrity of the waterproof membrane supported by the thermally insulating barrier.

An idea at the base of the invention consists in introducing a flexibility of the anchoring devices in the direction of a compressive force coming from the interior of the tank, with a view to homogenizing the response of a thermally insulating barrier. to compressive stresses. Another idea underlying the invention consists in allowing the upper surface of an anchoring device to approximately follow the movements of the upper surface of the insulating blocks during the operation of a sealed and thermally insulating tank. membrane.

For this, the invention proposes an anchoring device intended to retain insulating blocks against a load-bearing wall, comprising:
a clamping assembly comprising a lower plate, an upper plate parallel to the lower plate, a connecting member linking the lower plate to the upper plate and a spacing member arranged between the lower plate and the upper plate, the connecting member spacing comprising a rigid abutment part defining a minimum spacing between the lower plate and the upper plate in a position of abutment of the lower and upper plates against the abutment part, and
an anchor rod projecting from the clamping assembly perpendicular to the lower plate, the anchor rod comprising a lower end intended to be attached to a load-bearing wall and an upper end opposite the lower end and coupled to the lower plate to be able to exert traction on the lower plate in the direction of the lower end,
in which the spacing member further comprises an elastically compressible member tending to maintain the lower plate and the upper plate in a separated position, the connecting member defining a maximum spacing between the lower plate and the upper plate in the position separated, said maximum spacing being greater than said minimum spacing, the elastically compressible member being configured to elastically compress to said abutment position of the lower and upper plates against the abutment piece in response to a force tending to bring the upper plate closer together of the lower plate.

Thanks to these characteristics, the anchoring device can have a lower stiffness than in the aforementioned prior art in response to a compressive force and thus have a capacity for elastic deformation by crushing between the separated position and the abutment position.

According to other advantageous embodiments, such an anchoring device may have one or more of the following characteristics.

The connecting member which defines the maximum spacing between the lower plate and the upper plate can be made in different ways. According to one embodiment, the connecting member comprises at least one connecting rod perpendicular to the lower plate and to the upper plate and extending through a bore formed in the abutment part, a first stop element coupled at a first end of the connecting rod to stop the upper plate longitudinally with respect to the connecting rod in the separated position and a second stop element coupled to a second end of the rod for stopping the lower plate longitudinally with respect to the connecting rod in the separated position, at least one of the lower plate and the upper plate being mounted in a sliding manner with respect to said connecting rod in order to be able to slide as far as the abutment position.

The elastically compressible member can be arranged in different ways between the lower plate and the upper plate. The elastically compressible member can be mounted in series or in parallel with the abutment piece defining the minimum spacing.

According to one embodiment, the elastically compressible member is engaged on the connecting rod.

According to embodiments, the elastically compressible member bears against the abutment part and/or against at least one of the lower and upper plates.

According to one embodiment, the bore formed in the abutment part has a stage in which the elastically compressible member is arranged. Thanks to these characteristics, the elastically compressible member can have a small size.

The elastically compressible member can be made in different ways. According to one embodiment, the elastically compressible member comprises a stack of elastic washers. For example between 2 and 10 Belleville washers can be used to generate an elastic travel of between 1 and 6 mm.

The elastic movement between the separated position and the abutment position of the upper and lower plates preferably corresponds quite precisely to the movement of a cover plate of the insulating block between a state of rest corresponding to an empty tank and at room temperature and a state service corresponding to the operating conditions of the tank. This displacement is caused by thermal contraction and contraction of the insulating block under load from the pressure exerted by the cargo. It is preferable to consider a differential displacement between the upper surface of the insulating block and the upper surface of the anchoring device by subtracting the contraction of the other parts of the anchoring device under the same conditions. According to one embodiment, the elastic movement is between 1 and 6 mm, preferably 3 mm.

According to one embodiment, the connecting member is configured to exert a static load on the elastically compressible member in the separated position. Such a static load (or preload) makes it possible in particular to ensure reliable support of the overlying sealed membrane during vessel construction operations which are likely to generate localized pressures on the vessel wall (for example drilling operation localized damage to the leaktight membrane, or movement of a worker or tool on the vessel wall under construction). The static load is for example of the order of 1kN.

According to one embodiment, the lower plate has a central hole through which the upper end of the anchor rod passes, and the anchoring device comprises a nut which cooperates with a threaded portion of the upper end of the rod. anchor and one or more elastic washers threaded onto the upper end of the anchor rod between the nut and the lower plate so as to be able to exert an elastic force on the lower plate in the direction of the lower end of the rod anchor.

Preferably in this case, the clamping assembly comprises at least two connecting rods arranged symmetrically with respect to said central bore. Thanks to these characteristics, the forces can be distributed in a balanced way in the clamping assembly.

According to one embodiment, the or each connecting rod is locked in rotation by a spot weld on one or both plates, or by a split lock nut. The split lock nut is placed for example above, below or partially in the lower plate.

According to one embodiment, the anchoring device further comprises a spacer part arranged under the lower plate and having a central housing through which the anchor rod passes, the spacer part comprising an upper surface configured to bear against the plate bottom of the clamping assembly and a bottom surface intended to rest on an insulating block. The spacer piece is for example made of plywood to limit the thermal bridge. The spacer piece preferably has a section identical to the lower plate, of rectangular shape in the embodiments shown. It can be formed from a small number of elongated parts with simple shapes, rigidly assembled together, for example by stapling, screwing and/or gluing. The central housing is preferably filled with thermal insulation around the anchor rod, for example glass wool, wadding, expanded polystyrene or polyurethane foam.

According to one embodiment, the clamping assembly forms a secondary clamping member intended to cooperate with a secondary insulating barrier, the upper plate having a central bore into which is screwed a stud projecting from the clamping assembly at the opposite the anchor rod, said stud carrying a primary clamping member intended to cooperate with a primary insulating barrier.

According to one embodiment, the anchoring device further comprises a sleeve engaged on the lower end of the anchoring rod and intended to be fixed on the bearing wall, the sleeve having a housing receiving the lower end of the anchor rod so as to form a ball joint.

According to one embodiment, the clamping assembly has an overall parallelepipedal shape, the lower plate and the upper plate having a rectangular contour.

According to one embodiment, the anchor rod, the lower plate and the upper plate are made of metal, the abutment piece being made of plywood or another rigid material providing better thermal insulation than metal, for example polyurethane foam with a density greater than 200 kg/m ³ .

According to one embodiment, the invention also provides a sealed and thermally insulating tank for storing a fluid, comprising a supporting wall, anchoring devices fixed to the supporting wall and a tank wall anchored to the supporting wall at with the aid of the anchoring devices, the vessel wall having successively in a direction of thickness, from the outside towards the inside of the vessel, a thermally insulating barrier and a sealing membrane which rests against the thermally insulating,
in which the thermally insulating barrier comprises insulating blocks of parallelepipedal shape which are juxtaposed on the load-bearing wall, a said insulating block comprising a cover plate defining a support surface for the sealing membrane;
in which at least one said aforementioned anchoring device is used, the lower end of the anchoring rod being fixed to the load-bearing wall between a plurality of insulating blocks, the lower plate of the anchoring device cooperating with the plurality of insulating blocks in order to clamp the plurality of insulating blocks in the direction of the load-bearing wall.

According to other advantageous embodiments, such a tank may have one or more of the following characteristics.

According to one embodiment, the elastically compressible member is configured to maintain the lower plate and the upper plate in the separated position in an empty state of the tank, the upper plate of the anchoring device in the separated position being aligned with the cover plates of the plurality of insulating blocks to support the waterproofing membrane.

The insulating block can have different structures. According to one embodiment, a said insulating block comprises a bottom plate parallel to and spaced from the cover plate, a fiber-reinforced polymer foam block arranged between the cover plate and a bottom plate and the lower plate of the device anchor cooperates directly or indirectly with said bottom plate without exerting any clamping on the block of polymer foam. For example, the lower plate of the anchoring device can cooperate with the bottom plate by means of a rigid element such as a spacer piece, a pillar and/or a cleat, for example made of plywood.

According to one embodiment, a said insulating block comprises a bottom plate, and successively an intermediate plate and a cover plate parallel to the bottom plate and mutually spaced apart, and two blocks of fiber-reinforced polymer foam arranged respectively between the plate cover plate and the intermediate plate and between the intermediate plate and the bottom plate. The lower plate of the anchoring device cooperates directly with said intermediate plate at the level of a corner zone.

Preferably, the stiffness of the elastically compressible member is smaller than a stiffness in the thickness direction of the insulating barrier adjacent to the anchor device. According to one embodiment, a ratio between the stiffness of the elastically compressible member and a stiffness in the thickness direction of the vessel wall equivalent to a spring consisting of the polymer foam reinforced with fibers having a section equal to that of the upper platinum is between 0.3 and 1.

According to one embodiment, the thermally insulating barrier is a secondary thermally insulating barrier, the insulating blocks are secondary insulating blocks and the sealing membrane is a secondary sealing membrane, the vessel wall further comprising a thermally insulating barrier primary resting against the secondary sealing membrane and a primary sealing membrane which rests against the primary thermally insulating barrier and is intended to be in contact with the fluid contained in the tank; the primary thermally insulating barrier comprising primary insulating blocks which are each superimposed on one of the secondary insulating blocks,
wherein said stud passes through the secondary sealing membrane in leaktight manner and the primary clamping member is held bearing in the direction of the load-bearing wall against a plurality of primary insulating blocks superimposed on said plurality of secondary insulating blocks so as to retain the plurality of primary insulating blocks towards the load-bearing wall.

According to one embodiment, the fluid is a liquefied gas, such as liquefied natural gas, liquefied petroleum gas, liquefied ethylene.

Such a tank can be part of an onshore storage facility, a storage facility placed on the seabed, for example to store LNG, or be installed in a floating, coastal or deep-water structure, in particular an LNG carrier, a floating storage and regasification unit (FSRU), floating production and remote storage unit (FPSO) and others.

According to one embodiment, a vessel for transporting a fluid comprises a double hull and a aforementioned tank placed in the double hull. According to one embodiment, the double shell comprises an inner shell forming the carrier wall of the tank.

According to one embodiment, the invention also provides a transfer system for a fluid, the system comprising the aforementioned vessel, insulated pipes arranged so as to connect the tank installed in the hull of the vessel to a floating or terrestrial storage installation and a pump for driving a fluid through the insulated pipes from or to the floating or terrestrial storage installation to or from the tank of the ship.

According to one embodiment, the invention also provides a method for loading or unloading such a ship, in which a fluid is routed through insulated pipes from or to a floating or terrestrial storage installation to or from the tank of the ship.

Brief description of figures

The invention will be better understood, and other aims, details, characteristics and advantages thereof will appear more clearly during the following description of several particular embodiments of the invention, given solely by way of illustration and not limitation. , with reference to the accompanying drawings.

Figure 1 is a cutaway perspective view of a vessel wall.

Figure 2 is a side view of the vessel wall according to the arrow II of Figure 1, showing the anchoring device in a rest state on the left view and in a compressed state on the right view.

Figure 3 is a side view of an anchor used in the vessel wall of Figure 2, in the rest state.

Figure 4 is a half view similar to Figure 2, showing another embodiment of the anchoring device.

Figure 5 is a perspective view of spacer pieces according to three embodiments.

Figure 6 is a schematic top view of the vessel wall of Figure 2, showing the position of the anchoring device.

Figure 7 is a perspective view of another insulating block that can be used in the vessel wall of FIG. 1.

FIG. 8 is a cutaway diagrammatic representation of an LNG carrier tank and a loading/unloading terminal for this tank.

By convention, the terms "lower" and "upper" are used to define the relative position of one element in relation to another, respectively in the direction of the outside or the inside of the tank, as in the horizontal wall which is shown in Figure 1. However, the following description is applicable to any wall regardless of its orientation in the gravity field.

In Figure 1, there is shown the multilayer structure of a tank wall 1, sealed and thermally insulating for the storage of a liquefied fluid, such as liquefied natural gas (LNG). The vessel wall 1 comprises successively, in the direction of the thickness, from the outside towards the interior of the vessel, a secondary thermally insulating barrier 3 retained on a bearing wall 2, a secondary sealed membrane 4 resting against the barrier thermally insulating secondary 3, a thermally insulating primary barrier 5 resting against the secondary sealed membrane 4 and a primary sealed membrane 6 intended to be in contact with the liquefied natural gas contained in the tank.

The load-bearing wall 2 can in particular be formed by the hull or the double hull of a ship. The supporting wall 2 is typically part of a supporting structure comprising a plurality of walls defining the general shape of the tank, usually a polyhedral shape.

The secondary thermally insulating barrier 3 comprises a plurality of secondary insulating blocks 7 which are anchored to the load-bearing wall 2 by means of anchoring devices 20 which will be described in detail later. The secondary insulating blocks 7 have a generally parallelepipedal shape and are arranged in parallel rows.

The secondary sealing membrane 4 comprises a continuous layer of metal strakes 8 with raised edges. The metal strakes 8 are welded by their raised edges to parallel welding supports which are fixed in the grooves 9 made in the cover plates of the secondary insulating blocks 7. The metal strakes 8 are, for example, made of Invar®: c that is to say an alloy of iron and nickel whose coefficient of expansion is typically between 1.2.10 ^-6 and 2.10 ^-6 K ^-1 .

The primary thermally insulating barrier 5 comprises a plurality of primary insulating blocks 11 have a generally parallelepipedic shape and length and width dimensions identical to those of the secondary insulating blocks 7. Each of the primary insulating blocks 11 is positioned opposite one secondary insulating blocks 7, in alignment with the latter along the thickness direction of the vessel wall 1.

The primary sealing membrane 6 can be made in different ways. It comprises here a continuous sheet of metal strakes 8 with raised edges. As in the secondary sealing membrane 4, the metal strakes 8 are welded by their raised edges to parallel welding supports which are fixed in grooves made on the cover plates of the primary insulating blocks 11.

In FIG. 1, a secondary insulating block 7 has been omitted to show shims 12 and beads of mastic 13 intended to compensate for unevenness in the flatness of the bearing wall 2. Positioning shims, not shown, can also be provided as described in publication WO-A-2018069585.

The anchoring devices 20 are preferably positioned at the four corners of the secondary insulating blocks 7 and primary insulating blocks 11. Each stack of a secondary insulating block 7 and of a primary insulating block 11 is anchored to the load-bearing wall 2 by means of four anchoring devices 20. In addition, each anchoring device 20 cooperates with the corners of four adjacent secondary insulating blocks 7 and with the corners of four adjacent primary insulating blocks 11 .

In relation to FIG. 2, the structure of a secondary insulating block 7 according to one embodiment is observed more precisely. The secondary insulating block 7 here comprises a layer of insulating polymer foam 16 sandwiched between a bottom plate 14 and a cover plate 15. The bottom plate 14 and the cover plate 15 are for example made of plywood. The layer of insulating polymer foam 16 is bonded to the bottom plate 14 and the cover plate 15. The insulating polymer foam may in particular be a foam based on polyurethane, optionally reinforced with fibers.

Figure 6 shows more precisely the positioning of an anchoring device 20 between the corners of four adjacent secondary insulating blocks 7 according to one embodiment, in top view. The anchoring device 20 is represented by the contour of the clamping assembly 30. It can be seen that the bottom plate 14 of each secondary insulating block 7 includes a cutout 52 at the level of its corner zone to release a clearance 55 in rectangular chimney shape which receives the anchoring device 20.

The cover plate 15 and the layer of insulating polymer foam 16 of the secondary insulating block 7 comprise a recess 53 in the shape of a rectangular chimney which uncovers a corner portion 54 of the bottom plate 14. The corner portion 54 is intended to receive directly or indirectly the support of the anchoring device 20, for example via a spacer piece 50 which will be described below or a rigid element integral with the bottom plate 14, such as a pillar of 'angle.

With reference to Figures 2 and 3, we will now describe the structure of an anchoring device 20 according to one embodiment.

The anchoring device 20 essentially comprises a clamping assembly 30 and an anchoring rod 22. The lower end of the anchoring rod 22 is received in a socket 23 whose base is welded to the load-bearing wall 2 in one central position of clearance 55 between the corner zones of four adjacent secondary insulating blocks 7. The sleeve 23 forms a ball joint for the anchor rod 22. For example, it houses a nut 18 into which the lower end of the anchor rod 22 is screwed. The anchor rod 22 extends in the thickness direction of the vessel wall 1 and passes between the primary insulating blocks 22 adjacent.

The clamping assembly 30 comprises successively in the direction of thickness a lower plate 31, a spacer block 33 and an upper plate 32. The lower plate 31 and the upper plate 32 have the general shape of a rectangular parallelepiped comprising two large opposite faces which are parallel to the load-bearing wall 2. The contour of the spacer block 33 is also rectangular and of the same dimension. Alternatively, the outline shape of the clamp assembly 30 could be different, for example hexagonal or circular.

The lower plate 31 is held by the anchor rod 22 bearing in the direction of the load-bearing wall 2 against the corner portion 54 of each of the four adjacent secondary insulating blocks 7. In the embodiment shown, the spacer piece 50 is placed between the lower plate 31 and the corner portion 54 of each of the secondary insulating blocks 7 and thus transmits a clamping force to the bottom plate 14.

The upper end 44 of the anchor rod 22 is engaged through a central bore 41 of the lower plate 31 and in a housing 45 made in the spacer block 33. A nut 42 cooperates with a thread made at the level of the upper end 44 of the anchor rod 22 so as to retain the lower plate 31 in the direction of the load-bearing wall 2.

In the embodiment shown, the anchoring device 20 further comprises one or more spring washers 43, of the Belleville type. The elastic washers 43 are threaded onto the anchoring rod 22 between the nut 42 and the lower plate 31, which makes it possible to ensure an elastic anchoring of the secondary insulating blocks 7 on the bearing wall 2. In addition, advantageously , a locking member is welded locally to the upper end of the anchor rod 22, so as to prevent the unscrewing of the nut 42.

The spacing block 33 further comprises two bores which pass through it in the thickness direction of the vessel wall and in which are engaged two fixing screws 34 which connect the lower plate 31 and the upper plate 32 to two opposite faces. of the spacer block 33. More specifically, the lower end 35 of each fixing screw 34 is threaded and screwed into a tapped hole 38 of the lower plate 31. A split lock nut 37 is also screwed onto the lower end 35 against the upper surface of the lower plate 31, to lock the fixing screws 34 in the lower plate 31 in position. In a manner not shown, the split lock nut 37 can also be placed against the lower surface of the lower plate 31 .

At the opposite end, each fixing screw has a head 36, for example conical, slidably housed in a bore 46 of the upper plate 32. An abutment position of the head 36 against a bottom of the bore 46, shown in Figure 3 and on the left of Figure 2, defines a position of maximum spacing of the plates 32 and 31. The dimension of this maximum spacing is defined by the useful length of the fixing screws 34 between the lower plate 31 and the upper plate 32. This length can be finely adjusted during manufacture, by adjusting the length engaged by screwing into the tapped holes 38.

The spacing block 33 has a lower face and an upper face 48 parallel to the plates 32 and 31. The thickness of the spacing block 33 between the lower face and the upper face 48 defines a minimum spacing between the lower plate 31 and the upper plate 32. This minimum spacing is reached in an abutment position, represented on the right of FIG. 2, in which the lower plate 31 and the upper plate 32 are in abutment against the lower face and the upper face 48 of the block spacing 33.

The dimensional difference between the minimum spacing and the maximum spacing is represented by the arrow 40 and corresponds to a sliding play of the head 36 in the bore 46. Its dimension is determined according to the structure of the wall of the tank and the operating conditions of the tank so that the upper plate 32 can generally follow the depression of the cover plate 15 of the secondary insulating blocks 7 during the operation of the tank, in particular under the effect of the thermal contraction and static and dynamic pressures received by the vessel wall 1 in operation. These pressures can in particular lead to creep of the layer of insulating polymer foam 16. This dimension is typically a few millimeters.

Elastic elements 39, for example Belleville washers, are engaged on the two fastening screws 34 between the spacer block 33 and the upper plate 32 and maintain the plates 32 and 31 in the separated position shown in FIG. 3, in a state of rest. More specifically, the elastic elements 39 create a clearance equal to the dimensional difference 40 between the spacer block 33 and the upper plate 32. In response to a pressure force exerted on the upper plate 32, the Belleville washers 39 compress, erasing gradually this play, until the abutment position of the lower face 49 of the upper plate 32 against the upper face 48 of the spacing block 33.

More precisely, the elastic elements 39 are here housed in a stage 19 of large diameter of the bores receiving the fixing screws 34 and bear against a shoulder at the bottom of the stage 19. In the abutment position, the elastic elements 39 are fully contained in floor 19.

According to one embodiment, each fixing screw 34 carries a stack of Belleville washers arranged successively in mutually inverted positions, preferably in an odd number, for example 5, so that the two ends of the stack consist of the largest Belleville washer diameters.

Preferably, the fixing screws 34 are configured to generate a compression preload on the elastic elements 39 in the rest position, so that the upper plate 32 is able to receive moderate loads without sinking. For example, a preload of approximately 1000N is applied, which makes it possible to support the load of an adult man who could walk in line with the anchoring device 20 during the construction of the vessel.

The stiffness of the elastic elements 39 is determined according to the structure of the vessel wall and the operating conditions of the vessel so that the upper plate 32 can generally follow the depression of the cover plate 15 of the secondary insulating blocks 7 during operation of the vessel, in particular under the effect of thermal contraction and of the static and dynamic pressures received by the vessel wall 1 in operation. These pressures can in particular lead to creep of the layer of insulating polymer foam 16.

It will be noted that the elastic elements 39 can be positioned differently to fulfill the same functions. For example, the fixing screws 34 can be reversed, with the screw head 36 on the side of the lower plate 31 and then positioning the elastic elements 39 between the lower plate 31 and the spacer block 33. In another variant not shown, the spacer block 33 is divided into two parts in the thickness direction and the elastic members 39 are disposed between the two parts.

In another variant illustrated in FIG. 4 in half view, the screw head 36 is positioned in the upper plate 32 and the elastic elements 39 are positioned between the lower plate 31 and the spacer block 33. In this case, the upper plate 32 and spacer block 33 slide together with respect to the fixing screws 34. Furthermore, the rotational stop of the fixing screws 34 with respect to the lower plate 31 can be achieved by a spot weld or a counter-nut, not shown. In Fig. 4 the plates 32 and 31 are shown in the abutment position.

The tank wall 1 could be limited to the secondary insulating barrier 3 and the secondary sealed membrane 4 to produce a simple membrane tank. In the case where the primary insulating barrier 5 and the primary waterproof membrane 6 are present, the anchoring device 20 also comprises a primary stage. For this, the upper plate 32 has a threaded bore 47 in its center, in which is mounted a threaded base of a stud 27 intended for anchoring the primary insulating blocks 11. The stud 27 passes through a bore made through a metal strake 8 of the secondary waterproof membrane 4. The stud 27 has a flange which is welded to its periphery, around the hole, to ensure the tightness of the secondary waterproof membrane 4.

The primary stage of the anchoring device 20 also comprises a primary bearing plate 28 which rests in the direction of the load-bearing wall 2 on a bearing zone formed in each of the four adjacent primary insulating blocks 11 so as to hold against the secondary waterproof membrane 4. In the embodiment shown, each support zone 29 is formed by an overhanging part of a bottom plate of the primary insulating block 11.

A nut 29 cooperates with a thread provided at the upper end of the pin 27 so as to ensure the fixing of the primary support plate 28 on the pin 27. In the embodiment shown, the anchoring device 20 further comprises a Belleville-type elastic washer threaded onto the stud 27 between the nut 28 and the primary bearing plate 28, which ensures elastic anchoring of the primary insulating blocks 11 on the secondary sealed membrane 4.

FIG. 5 illustrates several embodiments of a spacer piece 50, 150 or 250 of the anchoring device 20, which each time has a central through housing 51 to allow the anchoring rod 22 to pass, an end surface upper 56 to receive the support of the lower plate 31 and a lower end surface 57 to exert a support on the secondary insulating block. The spacer piece 50, 150 or 250 is for example made of plywood to limit the thermal bridge. The spacer piece 50, 150 or 250 preferably has a section identical to the lower plate 3, of rectangular shape in the embodiments shown. It can be formed from a small number of elongated parts with simple shapes, rigidly assembled together, for example by stapling, screwing and/or gluing.

Not shown, the central through housing 51 is filled with thermal insulation around the anchor rod 22, for example glass wool, wadding, expanded polystyrene or polyurethane foam.

The spacer piece 50 or 250 is formed of two flat rectangular plates 58 forming the main faces of the spacer piece and two cleats 59 arranged between the two flat rectangular plates along the edges thereof. Each of the four parts thus forms a wall of the central through housing 51, which has a square or rectangular section.

The spacer piece 150 is formed of four identical profiled elongated pieces having a section in the shape of a rectangular trapezium, an inclined face of which forms a respective wall of the central through housing 51, which has a section in the shape of a diamond. To limit the thermal bridge, longitudinal cells are formed on either side of the central through housing 51 and also filled with an insulating material.

Sizing example

Due to the stiffness of the elastic elements 39, the clamping assembly 30 is in the separated position corresponding to the maximum spacing when the tank is empty and at room temperature, that is to say under the conditions of its construction. initial. In this state, the position of the upper platen 32 is adjusted to be aligned with the cover plate 15, so as to provide a uniform support surface for the secondary waterproof membrane 4.

During operation of the vessel, following the filling of the vessel with liquefied gas, phenomena of thermal contraction and contraction and creep under the hydrostatic load will occur in the secondary insulating barrier 3.

The thermal contractions are not identical in all materials and the layers of insulating polymer foam 16 tend to contract more than the plywood constituting the spacer piece 50 and the spacer block 33. In addition, the pressure loads are different depending on the position of the tank wall at the bottom, on the ceiling or on the sides. All the walls receive at least the service pressure of the vapor phase, which is for example 2 kPa or 5 kPa (20 or 50 mbar).

The stiffness of the elastic elements 39 can be dimensioned so that, after cooling and under the operating pressure of the vapor phase, the elastic compression of the elastic elements 39 allows an additional lowering of the upper plate 32 which is greater than or equal to the increased contraction and creep of the secondary insulating blocks 7 relative to the thermal contraction of the anchoring device 20. This increased contraction and creep of the secondary insulating blocks 7 is for example approximately 1 mm under the service pressure of the vapor phase. Thus the upper plate 32 follows the level of the cover plates 15 and does not risk generating a protruding zone liable to shear the secondary waterproof membrane 6.

The stiffness of the elastic elements 39 and the dimension of the gap 40 can also be dimensioned so that the clamping assembly 30 reaches the stop position, corresponding to the minimum spacing under the following conditions:
- either under hydrostatic loading, when the overlying primary insulating block receives maximum cargo pressure;
- or under dynamic loading, when the overlying primary insulating block receives an impact pressure due to the sloshing of the cargo exceeding a predetermined nominal threshold.

In all cases, the elastic elements 39 increase the flexibility of the anchoring device 20 and thus limit the risk of locally forming a hard point or a protruding zone which could accelerate the aging of the secondary waterproof membrane 6.

Preferably, the total stiffness of the elastic member acting between the two plates, namely here the elastic elements 39, is less than the equivalent stiffness of the thermally insulating barrier at the service temperature in the immediate vicinity of the anchoring device . In the illustrated embodiment, it is the layer of insulating polymer foam 16 which controls the stiffness of the thermally insulating barrier. In one embodiment, the total stiffness of the elastic elements 39 is approximately 1880N/mm, while the stiffness in the thickness direction of the vessel wall is equivalent to a spring consisting of the insulating polymer foam 16 having a section equal to that of the upper plate is approximately 1920N/mm, ie a stiffness ratio equal to 0.98. More generally, this ratio could be chosen between 0.3 and 1.

The structure of the secondary insulating block 7 is described above by way of example. Also, in another embodiment, the secondary insulating blocks 7 are likely to have another general structure, for example that described in document WO-A-2012127141. The secondary insulating blocks 7 are then made in the form of a box comprising a bottom plate, a cover plate and supporting webs extending, in the direction of thickness of the wall 1 of the vessel, between the bottom plate and the cover plate and delimiting a plurality of compartments filled with an insulating filling, such as perlite, glass or rock wool.

Another embodiment of the secondary insulating blocks is illustrated in Figure 7 at numeral 107. In Figure 7, elements similar or identical to those of the preceding figures bear the same reference numeral increased by 100 and are not described again. . The layer of insulating polymer foam is here divided into two lower and upper layers 16b and 16a separated by an intermediate plate 10, for example made of plywood, glued to them. The length of the upper layer 16a is smaller than the length of the lower layer 16b and uncovers a flange 10a at two longitudinal ends of the intermediate plate 10.

A rigid pillar 17 extends in the thickness direction of the lower layer 16b between the intermediate plate 10 and the bottom plate 114, in recesses provided at the four corners of the lower layer 16b. The rigid pillar 17 is partially plumb with the flanges 10a to take up the tightening force of the anchoring device 20, the lower plain 31 of which can here be applied directly to the flange 10a. Further details of the secondary insulating block 107 can be found in the publication WO-A-2014096600.

The primary insulating block 11 can be made in different ways, for example in the form of a layer of insulating polymer foam sandwiched between a bottom plate and a cover plate like the secondary insulating block 7.

The bottom plate then has grooves intended to receive the raised edges of the strakes 8 of the secondary sealing membrane 4. The cover plate also has grooves to receive welding supports.

The structure of the primary insulating panel 11 is described above by way of example. Also, in another embodiment, the primary insulating panels 22 are likely to have another general structure, for example that described in document WO-A-2012127141.

The technique described above for producing a tank wall having a single or two leaktight membranes can also be used in different types of tanks, for example to form a double membrane tank for liquefied natural gas (LNG) in an onshore installation or in a floating structure such as an LNG carrier or other.

Referring to Figure 8, a cutaway view of an LNG carrier 70 shows a sealed and insulated tank 71 of generally prismatic shape mounted in the double hull 72 of the ship. The wall of the tank 71 comprises a primary leaktight barrier intended to be in contact with the LNG contained in the tank, a secondary leaktight barrier arranged between the primary leaktight barrier and the double hull 72 of the ship, and two insulating barriers arranged respectively between the primary waterproof barrier and the secondary waterproof barrier and between the secondary waterproof barrier and the double hull 72.

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

FIG. 8 represents an example of a maritime terminal comprising a loading and unloading station 75, an underwater pipe 76 and an installation on land 77. The loading and unloading station 75 is a fixed off-shore installation comprising an arm 74 and a tower 78 which supports the mobile arm 74. The mobile arm 74 carries a bundle of insulated flexible pipes 79 which can be connected to the loading/unloading pipes 73. The orientable mobile arm 74 adapts to all sizes of LNG carriers . A connecting pipe, not shown, extends inside the tower 78. The loading and unloading station 75 allows the loading and unloading of the LNG carrier 70 from or to the shore installation 77. This comprises liquefied gas storage tanks 80 and connecting pipes 81 connected by the underwater pipe 76 to the loading or unloading station 75. The underwater pipe 76 allows the transfer of the liquefied gas between the loading or unloading station 75 and the shore installation 77 over a great distance, for example 5 km, which makes it possible to keep the LNG carrier 70 at a great distance from the coast during loading and unloading operations.

To generate the pressure necessary for the transfer of the liquefied gas, pumps on board the ship 70 and/or pumps fitted to the shore installation 77 and/or pumps fitted to the loading and unloading station 75 are used.

Although the invention has been described in connection with several particular embodiments, it is obvious that it is in no way limited thereto and that it includes all the technical equivalents of the means described as well as their combinations if these fall within the scope of the invention.

The use of the verb "to comprise", "to understand" or "to include" and of its conjugated forms does not exclude the presence of other elements or other steps than those set out in a claim.

In the claims, any reference sign in parentheses cannot be interpreted as a limitation of the claim.

Claims (22)

Anchoring device (20) intended to retain insulating blocks against a load-bearing wall, comprising:
a clamping assembly (30) comprising a lower plate (31), an upper plate (32) parallel to the lower plate, a connecting member (34) linking the lower plate to the upper plate and a spacing member arranged between the lower platen and the upper platen, the spacing member comprising a rigid abutment part (33) defining a minimum spacing between the lower platen and the upper platen in a position of abutment of the lower and upper plates against the abutment part , And
an anchor rod (22) projecting from the clamp assembly perpendicular to the lower plate (31), the anchor rod having a lower end intended to be attached to a load-bearing wall (2) and an opposite upper end at the lower end and coupled to the lower plate (31) to be able to exert traction on the lower plate in the direction of the lower end,
wherein the spacing member further comprises an elastically compressible member (39) tending to maintain the lower plate and the upper plate (32) in a separated position, the connecting member defining a maximum spacing between the lower plate and the upper plate in the separated position, said maximum spacing being greater than said minimum spacing, the elastically compressible member (39) being configured to compress elastically up to said abutment position of the lower and upper plates (31, 32) against the stop piece (33) in response to a force tending to bring the upper plate closer to the lower plate. Anchoring device according to Claim 1, in which the connecting member comprises at least one connecting rod (34) perpendicular to the lower plate and to the upper plate and extending through a bore made in the abutment part , a first stop element (36) coupled to a first end of the connecting rod to longitudinally stop the upper plate (32) with respect to the connecting rod in the spaced position and a second stop element (37, 38) coupled to a second end of the rod to stop the lower plate (31) longitudinally with respect to the connecting rod in the separated position, at least one of the lower plate and the upper plate being slidably mounted by relative to said connecting rod to be able to slide to the stop position. Anchoring device according to claim 2, in which the elastically compressible member (39) is engaged on the connecting rod (34). Anchoring device according to Claim 2, in which the elastically compressible member (39) bears against the abutment piece. Anchoring device according to Claim 3, in which the bore formed in the abutment part has a stage (19) in which the elastically compressible member (39) is arranged. Anchoring device according to one of Claims 1 to 5, in which the elastically compressible member (39) comprises a stack of spring washers. Anchoring device according to one of Claims 1 to 6, in which the elastic clearance between the separated position and the abutment position of the upper and lower plates (31, 32) is between 1 and 6 mm. Anchoring device according to one of Claims 1 to 7, in which the connecting member (34) is configured to exert a static load on the elastically compressible member in the spaced apart position. Anchoring device according to one of Claims 1 to 8, in which the lower plate (31) has a central bore (41) through which the upper end of the anchoring rod (22) passes, in which the device for anchor comprises a nut (42) which cooperates with a threaded portion of the upper end of the anchor rod and one or more spring washers (43) threaded onto the upper end of the anchor rod between the nut and the lower plate so as to be able to exert an elastic force on the lower plate in the direction of the lower end of the anchor rod. Anchoring device according to Claim 9 taken in combination with Claim 2, in which the clamping assembly (30) comprises at least two connecting rods (34) arranged symmetrically with respect to the said central bore (41). Anchoring device according to one of Claims 1 to 10, further comprising a spacer part (50, 150, 250) arranged under the lower plate and having a central housing (51) through which the anchor rod passes, the part spacer comprising an upper surface (56) configured to bear against the lower plate of the clamping assembly and a lower surface (57) intended to bear against an insulating block. Anchoring device according to one of Claims 1 to 11, further comprising a sleeve (23) engaged on the lower end of the anchoring rod and intended to be fixed on the bearing wall (2), the sleeve having a housing receiving the lower end of the anchor rod (22) so as to form a ball joint. Anchoring device according to one of Claims 1 to 12, in which the clamping assembly (30) has an overall parallelepiped shape, the lower plate and the upper plate having a rectangular outline. Sealed and thermally insulating tank for storing a fluid, comprising a supporting wall, anchoring devices (20) fixed to the supporting wall (2) and a tank wall (1) anchored to the supporting wall using of said anchoring devices, the tank wall (1) successively presenting in a direction of thickness, from the outside towards the inside of the tank, a thermally insulating barrier (3) and a sealing membrane (4) which rests against the thermally insulating barrier (3),
wherein the thermally insulating barrier (3) comprises insulating blocks (7) of parallelepipedal shape which are juxtaposed on the load-bearing wall (2), a said insulating block comprising a cover plate defining a support surface for the sealing membrane (4);
wherein at least one said anchoring device is according to one of claims 1 to 13, the lower end of the anchoring rod (22) being fixed to the load-bearing wall between a plurality of insulating blocks (7), the lower plate (31) of the anchoring device cooperating with the plurality of insulating blocks (7, 107) in order to tighten the plurality of insulating blocks in the direction of the load-bearing wall (2). Tank according to claim 14, in which the elastically compressible member (39) is configured to maintain the lower platen and the upper platen in the separated position in an empty state of the tank, the upper platen (32) of the anchoring device in the spaced apart position being aligned with the cover plates of the plurality of insulating blocks to support the sealing membrane (4). A tank according to claim 14 or 15, wherein a said insulating block comprises a bottom plate (14) parallel to and spaced from the cover plate (15), a fiber reinforced polymer foam block (16) arranged between the cover and a bottom plate and in which the lower plate of the anchoring device cooperates directly or indirectly with said bottom plate (14) without exerting any clamping on the polymer foam block (16). Tank according to Claim 14 or 15, in which a said insulating block (107) comprises a bottom plate (114), and successively an intermediate plate (10) and a cover plate (115) parallel to the bottom plate and mutually spaced apart, and two blocks of fiber-reinforced polymer foam (16a, 16b) arranged respectively between the cover plate and the intermediate plate and between the intermediate plate and the bottom plate, in which the lower plate (31) of the device anchor cooperates directly with said intermediate plate (10) at a corner zone. A tank according to claim 16 or 17, wherein a ratio between the stiffness of the elastically compressible member and a stiffness in the thickness direction of the tank wall equivalent to a spring made of the fiber reinforced polymer foam having a section equal to that of the upper plate is between 0.3 and 1. Tank according to any one of Claims 14 to 18, in which the thermally insulating barrier is a secondary thermally insulating barrier (3), the insulating blocks are secondary insulating blocks (7) and the sealing membrane is a membrane of secondary sealing (4), the vessel wall further comprising a primary thermally insulating barrier (5) resting against the secondary sealing membrane (4) and a primary sealing membrane (6) which rests against the primary thermally insulating barrier (5) and is intended to be in contact with the fluid contained in the tank; the primary thermally insulating barrier (5) comprising primary insulating blocks (11) which are each superimposed on one of the secondary insulating blocks (7),
wherein the clamping assembly (30) forms a secondary clamping member intended to cooperate with the secondary insulating barrier, the upper plate (32) having a central bore (47) into which is screwed a stud (27) projecting from the clamping assembly opposite the anchor rod, said stud (27) carrying a primary clamping member (28) intended to cooperate with the primary insulating barrier (5), and in which said stud (27) passes through the secondary sealing membrane (4) in leaktight manner and the primary clamping member is held bearing in the direction of the load-bearing wall (2) against a plurality of primary insulating blocks (11) superposed on said plurality of insulating blocks secondary so as to retain the plurality of primary insulating blocks towards the load-bearing wall (2). Vessel (70) for the transport of a fluid, the vessel comprising a double hull (72) and a tank (71) according to any one of claims 14 to 19 arranged in the double hull (72). Transfer system for a fluid, the system comprising a vessel (70) according to claim 20, insulated pipes (73, 79, 76, 81) arranged to connect the tank (71) installed in the hull of the vessel to a floating or onshore storage facility (77) and a pump for driving fluid through the insulated pipelines from or to the floating or onshore storage facility to or from the vessel's tank. Method of loading or unloading a ship (70) according to claim 20, in which a fluid is conveyed through insulated pipes (73, 79, 76, 81) from or to a floating or terrestrial storage installation (77) to or from the tank (71) of the ship.