WO2023089156A1

WO2023089156A1 - Sealed and thermally insulating tank

Info

Publication number: WO2023089156A1
Application number: PCT/EP2022/082536
Authority: WO
Inventors: Antoine PHILIPPE; Patrick Martin; Antoine Benoit; Sébastien DELANOE
Original assignee: Gaztransport Et Technigaz
Priority date: 2021-11-22
Filing date: 2022-11-21
Publication date: 2023-05-25
Also published as: FR3129455A1; TW202332857A; KR20230076826A; CN116490720A

Abstract

The invention relates to a sealed and thermally insulating tank for storing a fluid, integrated into a load-bearing structure, having a secondary insulating block and a primary insulating block anchored to the secondary insulating block by a primary anchoring system (97) having a movable part (102) disposed in a housing formed in a cover plate (10), the movable part having an upper face flush with the support surface, a retaining part (101) fixed to the cover plate keeping the movable part in the housing in a thickness direction, the movable part being able to move at least parallel to a longitudinal direction of the welding flange, the movable part having a sliding layer (106) covering at least one surface of the body, the sliding layer being in contact with the retaining part and having a coefficient of friction lower than that of the movable part.

Description

Watertight and thermally insulated tank

The invention relates to the field of sealed and thermally insulating membrane tanks. In particular, the invention relates to the field of sealed and thermally insulating tanks for the storage and/or transport of liquefied gas at low temperature, such as tanks for the transport of Liquefied Petroleum Gas (also called LPG) having for example a temperature between -50°C and 0°C, or for the transport of Liquefied Natural Gas (LNG) at around -162°C at atmospheric pressure. These tanks can be installed on land or on a floating structure. 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.

In one embodiment, the liquefied gas is LNG, at atmospheric pressure. Other liquefied gases can also be considered, in particular ethane, propane, butane, hydrogen or ethylene.

Technology background

Vessel tanks for the transport of liquefied natural gas generally comprise a double wall comprising successively, from the inside towards the outside of the tank, a primary waterproof membrane, a primary thermally insulating barrier, a secondary waterproof membrane and a thermally secondary insulation. The secondary insulating barrier includes a secondary insulating block comprising a cover plate forming a support surface for the secondary waterproof membrane.

Patent application FR 3 090 810 describes a sealed and insulating tank wall in which an anchoring system makes it possible to anchor a primary insulating block to the secondary insulating block. The anchoring system includes a base attached to the cover plate. A movable part is retained in the base in a direction of thickness of the wall and movably mounted in the base. The moving part has a tapped hole opening onto an upper surface of the moving part. The upper surface of the movable part is flush with an upper surface of the cover plate and the movable part is mounted in the free base in translation at least parallel to the longitudinal direction of the welding flange.

However, the proposed anchoring system does not give full satisfaction. Indeed, the moving part is subject to seizure phenomena, caused in particular by an excessively high coefficient of friction of the metal part as well as by the lack of homogeneity of the coefficient of friction on the surface of an untreated metal part.

Summary

One idea underlying the invention is to limit the seizing of the moving part present in the primary anchoring system of a sealed and thermally insulating tank.

Another idea underlying the invention is to promote sliding of the moving part only in the desired directions.

According to one embodiment, the invention provides a sealed and thermally insulating tank for storing a fluid, the tank comprising a wall of the tank successively comprising, in a direction of thickness, a secondary insulating barrier retained at a load-bearing wall , a secondary waterproof membrane resting against the secondary insulating barrier, a primary insulating barrier resting against the secondary waterproof membrane and a primary waterproof membrane resting against the primary insulating barrier,
wherein the secondary insulating barrier comprises a secondary insulating block comprising a cover plate forming a support surface for the secondary waterproof membrane,
wherein said secondary waterproof membrane comprises a plurality of metal strakes, the metal strakes having raised edges towards the inside of the tank, said metal strakes being welded in pairs, by their raised edges on two faces of a welding wing mechanically retained on the secondary block, said welding wing being partially engaged in a groove formed in the cover plate and extending in a longitudinal direction,
in which the primary insulating barrier comprises a primary insulating block anchored to the secondary insulating block by a primary anchoring system,
the primary anchoring system comprising:
a recess formed in the cover plate and opening onto said support surface,
a movable part disposed in the housing, the movable part comprising a body having an upper face flush with the support surface, and
a retainer attached to the cover plate and cooperating with the movable part so as to stop the movable part in the housing in the thickness direction,
the housing and the retainer being configured to allow movement of the moving part at least parallel to the longitudinal direction of the welding flange,
in which the moving part comprises a sliding layer covering at least one surface of the body, the sliding layer being in contact with the retaining part and having a coefficient of friction lower than said body

Thanks to these characteristics, the sliding layer improves the durability of the primary anchoring system. Indeed, by having a coefficient of friction lower than said body, the moving part can thus move in the body while minimizing the friction between these two parts and thus limiting the forces applied to the welds between the primary anchoring and the secondary membrane and thereby increasing the life of the primary anchoring system. This also makes it possible to maintain movement of the mobile part only in the desired direction and thus to avoid jamming of the part.

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

According to one embodiment, a compressible material is inserted into interstices located between the retaining part and the moving part or between the moving part and the walls of the housing. The compressible material is insulating and is for example chosen from polymer foams and mineral wools. Thanks to the compressible nature of the material, it is possible to adjust the initial position of the moving part to a centered position allowing the moving part good freedom of movement in one direction or the other during commissioning.

According to one embodiment, the compressible material can be a low stiffness spring.

According to one embodiment, the sliding layer is made of polymer.

According to one embodiment, the sliding layer is chosen from the following polymers: PTFE (polytetrafluoroethylene), PCTFE (polychlorotrifluoroethylene), POM (polyoxymethylene) preferably type H for homopolymer, PEI (polyetherimide), PAEK (polyaryletherketone), PEEK (polyetheretherketone).

According to one embodiment, the polymer is fiber-reinforced, for example with fiberglass. This has the advantage of increasing the material's resistance to creep and reducing the coefficient of thermal contraction of the sliding layer.

According to one embodiment, the polymer sliding layer is made of a polymer filled with particulate fillers, the particulate fillers preferably comprising nanofillers. This has the advantage of increasing, depending on the materials used, either the hardness of the polymer or its sliding capacity during contact between the stressed surfaces. A nanofiller is defined by its dimension between 1 and 100 nanometers. The shape of the particulate fillers, in particular nanofillers, can be chosen for example from: sheet, fiber, granule and sphere.

According to one embodiment, the particulate fillers are made of at least one material selected from: carbon, graphite, glass, cellulose, and bronze.

According to one embodiment, the sliding layer is obtained by surface treatment of said at least one surface of the body.

According to one embodiment, the surface treatment is a nitriding treatment.

According to one embodiment, the sliding layer is placed on a surface of the retaining part in contact with the moving part.

According to one embodiment, the sliding layer is placed on a surface of the retaining part in contact with the moving part and on the moving part.

According to one embodiment, the housing has a depth in the direction of thickness such that the movable part is flush with the support surface and a length in the longitudinal direction and a width in a transverse direction such that the movable part can move at the least parallel to the longitudinal direction of the metal strakes.

According to one embodiment, the cover plate comprises a countersink on the edge of the housing, the countersink receiving the retainer, the countersink having a depth such that the retainer is flush with the support surface, in which the retainer covers completely the housing and the counterbore and has an opening, the upper face of the body flush through said opening.

According to one embodiment, the movable part comprises a base having a width greater than that of the opening in the retaining part.

According to one embodiment, the movable part comprises an upper part having a width equal to that of said opening, the upper part being flush with an upper surface of the retaining part.

According to one embodiment, at least the base of the moving part includes the sliding layer.

According to one embodiment, an upper surface of the base is covered by the slip layer. This reduces friction between the moving part and a bottom surface of the retainer.

According to one embodiment, one side of the upper part is covered by the sliding layer. This reduces friction between the moving part and an edge of the retainer opening.

According to one embodiment, the retaining piece is a retaining plate. According to one embodiment, the retaining piece is made of steel, for example stainless steel and/or cryogenic steel.

According to one embodiment, the retaining plate is fixed to the cover plate by fasteners placed on the periphery of the retaining plate, so that the fasteners are arranged outside the housing around the housing and/or by gluing .

Thanks to these characteristics, the fasteners, for example screws or rivets, are not likely to come into contact with the moving part.

According to one embodiment, the moving part comprises a tapped hole opening onto said upper face of the moving part and the primary anchoring system further comprises a stud having a threaded lower part screwed into the tapped hole.

According to one embodiment, the stud has a flange extending above the moving part, in which the flange is welded on the periphery to the secondary waterproof membrane in a leaktight manner.

Such a tank can be part of an onshore storage facility, 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) , a floating production and remote storage unit (FPSO) and others. Such a tank can also serve as a fuel tank in any type of ship.

According to one embodiment, the primary anchoring system further comprises at least one washer and at least one nut cooperating with threaded upper parts of said stud to retain said washer resting on a bottom plate of the primary insulating block.

According to one embodiment, a vessel for the transport of a cold liquid product comprises a double hull and an aforementioned tank arranged in the double hull.

According to one embodiment, the invention also provides a transfer system for a cold liquid product, 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 storage installation or land and a pump to drive a flow of cold liquid product through the insulated pipes from or to the floating or land storage facility to or from the ship's tank.

According to one embodiment, the invention also provides a method for loading or unloading such a ship, in which a cold liquid product is conveyed through insulated pipes from or to a floating or terrestrial storage installation to or from the ship's tank.

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.

There is a cutaway perspective view of a vessel wall.

There is a schematic sectional view of detail II of the illustrating an anchoring system cooperating with a stud according to a first embodiment.

There is a schematic top view of the anchoring system according to the first embodiment comprising in particular a moving part and a retaining part.

There is a schematic perspective view of the moving part of the .

There is a schematic perspective view of the moving part according to a second embodiment.

There is a schematic perspective view of the moving part according to a third embodiment.

There is a schematic perspective view of the moving part according to a fourth embodiment

There is a schematic perspective view of the moving part according to a fifth embodiment

There is a schematic perspective view of the moving part according to a sixth embodiment.

There is a schematic perspective view of the moving part according to a seventh embodiment.

There is a schematic perspective view of a retainer according to a first variant.

There is a schematic perspective view of the retainer according to a second variant.

There is a cutaway schematic representation of an LNG tank and a loading/unloading terminal for this tank.

On the , there is shown the multilayer structure of a sealed and thermally insulating tank 1 for storing a liquefied fluid, such as liquefied natural gas (LNG). The tank 1 has a generally polyhedral shape and comprises several walls. The wall of the tank 1 comprises successively, in the direction of the thickness, from the outside towards the inside of the tank 1, a secondary thermally insulating barrier 2 retained on a supporting structure 3, a secondary sealed membrane 4 resting against the secondary thermally insulating barrier 2, a primary thermally insulating 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 1.

The supporting structure of the tank 1 can in particular be formed by the hull or the double hull of a ship. The load-bearing structure comprises a plurality of load-bearing walls 3 defining the general shape of the view, usually a polyhedral shape.

The secondary thermally insulating barrier 2 comprises a plurality of secondary insulating blocks 7 which are anchored to the load-bearing wall 3 by means of secondary anchoring systems 98. The secondary insulating blocks 7 have a generally parallelepipedal shape and are arranged in parallel rows. Three rows are indicated by the letters A, B and C. Mastic sausages (not shown) are interposed between the secondary insulating blocks 7 and the load-bearing wall 3 to compensate for the differences of the load-bearing wall 3 with respect to a flat surface of reference. A kraft paper can be inserted between the mastic rolls and the load-bearing wall 3 if desired to prevent the mastic rolls from sticking to the load-bearing wall 3.

It is observed that the secondary waterproof membrane 4 comprises a continuous layer of strakes 21, metal, with raised edges 32 towards the inside of the tank. The strakes 21 are welded two by two, by their raised edges 32, on both sides of a welding wing. Weld wings have a square-shaped section. The raised edges 32 of the strakes 21 are welded to one arm of the bracket, while the other arm is engaged in a groove 20 provided on the cover plates 10 of the secondary insulating blocks 7. The cover plates 10 comprise a plurality of parallel grooves 20, the distance between two grooves 20 corresponding to the width of a strake 21, while the distance between a free edge of a block and an adjacent groove 20 corresponds to the width of a strake 21, so that a strake forms the junction between two adjacent insulating blocks 7. Thus, the secondary waterproof membrane 4 is retained on the secondary thermally insulating barrier 2. The weld flanges and the grooves 20 form sliding joints allowing the strakes 21 to contract and deform relative to the secondary insulating blocks 7.

The primary thermally insulating barrier 5 comprises a plurality of superposed primary insulating blocks 22 straddling two rows of secondary insulating blocks 7. The primary insulating blocks 22 are anchored to the secondary insulating blocks 7 by means of primary anchoring systems 97. primary anchoring systems 97 are separated and offset from the secondary anchoring systems 98. The primary insulating blocks 22 have a generally parallelepipedic shape and are arranged in parallel rows. In addition, they have dimensions identical to those of the primary insulating blocks 22 with the exception of their thickness in the direction of thickness of the wall 1 of the vessel which is likely to be different, and in particular lower. The primary thermally insulating barrier 5 is surmounted by a metal sealing barrier with corrugations. Alternatively, the thermally insulating barrier 5 could be surmounted by a metal sealing barrier composed of strakes.

There represents the primary anchoring system 97, according to a first embodiment. The primary anchoring system 97 includes a moving part 102 held in place by a retaining part 101. The moving part 102 is placed in a recess 108 hollowed out in the cover plate 10 and the retaining part 101 is placed in a counterbore 109, so that retainer 101 is flush with an upper surface of cover plate 10. Retainer 101 is secured to cover plate 10 by clips 34 and/or by gluing.

In a preferred embodiment, the cover plate 10 comprises in particular a layer of plywood with a thickness of between 15 and 24 millimeters, in which the housing is hollowed out.

At the level of a tapped hole 104 of the moving part 102, the sealed membrane 4 is pierced to allow the passage of a stud 35. The stud 35 then allows the fixing of the secondary insulating block 7 to the primary insulating block 22.

There represents the primary anchoring system 97, according to the first embodiment, seen from above. An opening 103 where the moving part 102 is flush is also filled with a piece of compressible insulating material 105. On the , the piece of compressible insulating material 105 is shown on only one side of the moving part 102, but another identical part can also be placed on the other side to initially center the moving part 102 with respect to the opening 103. A sliding layer 106 covers at least one side of the moving part 102.

The pre-positioning of the movable part 102, for example a centered pre-positioning, obtained thanks to the pieces of compressible insulating material 105 ensures that a certain range of mobility exists in one direction or the other in the longitudinal direction of the strakes. 21. This mobility makes it possible to adjust the position of the pin 35, if necessary, either during the welding of the secondary waterproof membrane 4 to catch up with positioning tolerances, or during the operation of the tank to absorb deformations which may have various causes.

Figures 4 to 10 show different embodiments of the mobile part 102-702 of the primary anchoring system while Figures 11 and 12 show two variant embodiments of the retaining part 101-201.

There represents the moving part 102 according to the first embodiment. The moving part 102 comprises an upper part 114 and a lower part 110. The lower part 110 is a rectangular parallelepipedal base and the upper part 114 is of rectangular section and has a shorter length than that of the lower part 110. The moving part 102 comprises a tapped hole 104 made on an upper surface of the upper part 114, which allows the passage of a stud 35. The movable part 102 is surrounded by a sliding pad 106 which is a polymer layer. The lower part 110 and the upper part 114 are for example made of stainless steel. The sliding pad 106 is disposed on an edge of the upper surface of the upper part 114, on sides 115 of the upper part 114 and on an upper surface 111 of the lower part 110 not covered by the upper part 114. The sliding shoe 106 can be made of a single block.

According to a variant not shown, the sliding shoe 106 can be replaced by a nitriding treatment applied to the moving part 102 on the sides 115 of the upper part 114 and on the upper surface 111 of the lower part 110.

There represents the moving part 202 according to a second embodiment. The second embodiment differs from the first embodiment in that the upper part 214 is cylindrical with a tapped hole 204. The lower part 210 is a base of rectangular section. In this embodiment, an upper surface 211 of the lower part 210 comprises a slip layer. One side 215 of top 214 may also include a slip layer. The sliding layer 206 is obtained either by surface treatment of the upper surface 211 (and optionally of the side 215), or by covering the upper surface 211 (and optionally the side 215) with a sliding pad.

There represents the moving part 302 according to a third embodiment. The third embodiment differs from the second embodiment in that the upper part 314 is of rectangular section with rounded edges, with dimensions in a longitudinal direction and in a transverse direction smaller than those of the lower part 310. In this embodiment, the sliding layer 306 is obtained by surface treatment of an upper surface 311 of the lower part 310 and, optionally, of the sides 315 of the upper part 314 or by covering said upper surface 311 and optionally said sides 315 with a sliding pad.

There represents the moving part 402 according to a fourth embodiment. The fourth embodiment differs from the second embodiment in that the upper part 414 is of rectangular section and has a dimension in a longitudinal direction identical to that of the lower part 410. In this embodiment, the sliding layer 406 is obtained by surface treatment of an upper surface 411 of the lower part 410 and, optionally, of the sides 415 of the upper part 414, or by covering the said upper surface 411 and optionally the said sides 415 with a sliding pad.

There represents the moving part 502 according to a fifth embodiment. The fifth embodiment differs from the fourth embodiment in that the upper part 514 has rounded edges. In this embodiment, the sliding layer 506 is obtained by surface treatment of an upper surface 511 of the lower part 510 and, optionally, of the sides 515 of the upper part 514, or by covering said upper surface 511 and optionally said sides 515 with a sliding pad.

There represents the moving part 602 according to a sixth embodiment. The sixth embodiment differs from the first embodiment in that the polymer slider 606 has dimensions in the longitudinal direction and in the transverse direction greater than that of the lower part 610.

There represents the moving part 702 according to a seventh embodiment. The seventh embodiment differs from the second embodiment in that the sliding shoe 706 is made of polymer and is of parallelepipedal shape with rounded edges and has a dimension in the longitudinal direction identical to that of the lower part 710. The part bottom 710 is also covered by the sliding shoe 706.

According to variants not shown, the sliding

shoe

606 or 706 can be replaced by a surface treatment of an upper surface of the

lower part

610 or 710 and, optionally, of the side of the

upper part

614 or 714.

There represents the retainer according to a first variant. According to this first variant, the retainer 101 is a rectangular-shaped retaining plate, with a rectangular opening where the movable part 102-702 is flush and with four tapped holes 119 at the ends to fix the fasteners 34 there.

There represents the retainer according to a second variant. This second variant differs from the first in that the retaining plate 201 is circular in shape.

The two retaining part variants are in particular compatible with all the embodiments of the moving part.

In other variants not shown, the retainer can be made in various other ways, for example by having another shape and having a different number of tapped holes.

With reference to the , 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.

There represents an example of a maritime terminal comprising a loading and unloading station 75, an underwater pipeline 76 and an installation on land 77. The loading and unloading station 75 is a fixed offshore installation comprising a mobile 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

Sealed and thermally insulating tank (1) for storing a fluid, the tank (1) comprising a wall of the tank successively comprising, in a direction of thickness, a secondary insulating barrier (2) retained on a load-bearing wall (3 ), a secondary waterproof membrane (4) resting against the secondary insulating barrier (2), a primary insulating barrier (5) resting against the secondary waterproof membrane (4) and a primary waterproof membrane (6) resting against the primary insulating barrier ( 5),
wherein the secondary insulating barrier (2) comprises a secondary insulating block (7) comprising a cover plate (10) forming a support surface for the secondary waterproof membrane (4),
wherein said secondary waterproof membrane (4) comprises a plurality of metal strakes (21), the metal strakes (21) having raised edges (32) towards the inside of the tank, said metal strakes (21) being welded two to two, by their raised edges (32) on two faces of a welding wing mechanically retained on the secondary insulating block (7), the said welding wing being partially engaged in a groove (20) made in the cover plate (10 ) and extending in a longitudinal direction,
in which the primary insulating barrier (5) comprises a primary insulating block (22) anchored to the secondary insulating block (7) by a primary anchoring system (97),
the primary anchoring system (97) comprising:
- a recess formed in the cover plate and opening onto said support surface,
- a moving part (102, 202, 302, 402, 502, 602, 702) arranged in the housing, the moving part comprising a body, and
- a retainer (101, 201) fixed to the cover plate (10) and cooperating with the moving part (102, 202, 302, 402, 502, 602, 702), so as to stop the moving part in the housing in the thickness direction,
the housing and the retaining part (101, 201) being configured to allow movement of the moving part (102, 202, 302, 402, 502, 602, 702) at least parallel to the longitudinal direction of the metal strakes,
wherein the retainer (101) has an opening (103), the body having a base (110, 210, 310, 410, 510, 610, 710) and a top (114, 214, 314, 414, 514 , 614, 714), the top having a top surface flush with a top surface of the retainer through said opening, the base having a width greater than a width of the opening in the retainer (101, 201) ,
wherein the moving part (102, 202, 302, 402, 502, 602, 702) has a slip layer (106, 206, 306, 406, 506, 606, 706) of polymer covering at least one top surface (111 , 211, 311, 411, 511) of the base (110, 210, 310, 410, 510, 610, 710) of the body, the slip layer (106, 206, 306, 406, 506, 606, 706) being in contact with the retainer (101, 201) and having a coefficient of friction lower than said body,
wherein the cover plate (10) has a counterbore at the edge of the housing, the counterbore receiving the retainer (101), the counterbore having a depth such that the retainer (101) is flush with the support surface, the counterbore retainer (101) completely covering the housing and the counterbore, and
wherein the slip layer (106, 206, 306, 406, 506, 606, 706) of polymer further covers one side (115, 215, 315, 415, 515) of the upper body.
Cell according to claim 1, wherein the polymer sliding layer is made of a polymer filled with particulate fillers, the particulate fillers preferably comprising nanofillers.
A tank according to claim 2, wherein the particulate fillers are made of at least one material selected from: carbon, graphite, glass, cellulose and bronze.
Sealed and thermally insulating tank (1) for storing a fluid, the tank (1) comprising a wall of the tank successively comprising, in a direction of thickness, a secondary insulating barrier (2) retained on a load-bearing wall (3 ), a secondary waterproof membrane (4) resting against the secondary insulating barrier (2), a primary insulating barrier (5) resting against the secondary waterproof membrane (4) and a primary waterproof membrane (6) resting against the primary insulating barrier ( 5),
wherein the secondary insulating barrier (2) comprises a secondary insulating block (7) comprising a cover plate (10) forming a support surface for the secondary waterproof membrane (4),
wherein said secondary waterproof membrane (4) comprises a plurality of metal strakes (21), the metal strakes (21) having raised edges (32) towards the inside of the tank, said metal strakes (21) being welded two to two, by their raised edges (32) on two faces of a welding wing mechanically retained on the secondary insulating block (7), the said welding wing being partially engaged in a groove (20) made in the cover plate (10 ) and extending in a longitudinal direction,
in which the primary insulating barrier (5) comprises a primary insulating block (22) anchored to the secondary insulating block (7) by a primary anchoring system (97),
the primary anchoring system (97) comprising:
- a recess formed in the cover plate and opening onto said support surface,
- a moving part (102, 202, 302, 402, 502, 602, 702) arranged in the housing, the moving part comprising a body, and
- a retainer (101, 201) fixed to the cover plate (10) and cooperating with the moving part (102, 202, 302, 402, 502, 602, 702), so as to stop the moving part in the housing in the thickness direction,
the housing and the retaining part (101, 201) being configured to allow movement of the moving part (102, 202, 302, 402, 502, 602, 702) at least parallel to the longitudinal direction of the metal strakes,
wherein the retainer (101) has an opening (103), the body having a base (110, 210, 310, 410, 510, 610, 710) and a top (114, 214, 314, 414, 514 , 614, 714), the top having a top surface flush with a top surface of the retainer through said opening, the base having a width greater than a width of the opening in the retainer (101, 201) ,
wherein the moving part (102, 202, 302, 402, 502, 602, 702) has a sliding layer (106, 206, 306, 406, 506, 606, 706) in contact with the retainer (101, 201) and having a coefficient of friction lower than said body,
the sliding layer (106, 206, 306, 406, 506, 606, 706) being obtained by surface treatment of at least one surface of the body, in which the sliding layer (106, 206, 306, 406, 506 , 606, 706) forms an upper surface (111, 211, 311, 411, 511) of the base (110, 210, 310, 410, 510, 610, 710) of the body and a side (115, 215, 315, 415, 515) of the upper body,
wherein the cover plate (10) has a counterbore at the edge of the housing, the counterbore receiving the retainer (101), the counterbore having a depth such that the retainer (101) is flush with the support surface, the counterbore retainer (101) completely covering the housing and the counterbore.
Tank according to Claim 4, in which the surface treatment is a nitriding treatment.
Tank according to one of Claims 1 to 5, in which a compressible material (105) is inserted into interstices located between the retaining part (101, 201) and the movable part (102, 202, 302, 402, 502, 602, 702) or between the moving part and the walls of the housing.
Tank according to one of Claims 1 to 6, in which the housing has a depth in the thickness direction such that the movable part (102, 202, 302, 402, 502, 602, 702) is flush with the support surface and a length in the longitudinal direction and a width in a transverse direction such that the moving part can move at least parallel to the longitudinal direction of the metal strakes.
Tank according to one of Claims 1 to 7, in which the upper part (114, 214, 314, 414, 514, 614, 714) with the sliding layer has a width equal to the width of the said opening.
Tank according to one of Claims 1 to 8, in which the retaining part (101, 201) is a retaining plate.
Tank according to Claim 9, in which the retaining plate is fixed to the cover plate (10) by fasteners (34) placed on the periphery of the cover plate, so that the fasteners (34) are arranged at the exterior of the housing around the housing and/or by gluing.
Tank according to one of Claims 1 to 10, in which the moving part (102, 202, 302, 402, 502, 602, 702) comprises a tapped hole (104, 204, 304, 604, 704) opening onto the said face upper part of the movable part (102, 202, 302, 402, 502, 602, 702) and the primary anchoring system (97) further comprises a stud (35) having a threaded lower part screwed into the tapped hole (104 ).
Tank according to Claim 11, in which the stud (35) comprises a flange extending above the movable part (102, 202, 302, 402, 502, 602, 702), in which the flange is welded on the periphery on the secondary waterproof membrane (4) in a sealed manner.
Tank according to Claim 11 or 12, in which the primary anchoring system (97) further comprises at least one washer and at least one nut cooperating with threaded upper parts of the said stud (35) to retain the said washer resting on a bottom plate of the primary insulating block (22).
Vessel for transporting a cold liquid product, the vessel comprising a double hull and a tank arranged in the double hull, the tank being a tank according to one of Claims 1 to 13.
Transfer system for a cold liquid product, the system comprising a ship according to claim 14, insulated pipes arranged so as to connect the tank installed in the hull of the ship to a floating or terrestrial storage installation and a pump to drive a flow of cold liquid product through the insulated pipes from or to the floating or onshore storage facility to or from the ship's tank.
Method of loading or unloading a ship according to claim 14, in which a cold liquid product is conveyed through insulated pipes from or to a floating or terrestrial storage installation to or from the tank of the ship.