WO2019239048A1

WO2019239048A1 - Thermally insulating sealed tank

Info

Publication number: WO2019239048A1
Application number: PCT/FR2019/051395
Authority: WO
Inventors: Mickaël HERRY; Pierre Jean
Original assignee: Gaztransport Et Technigaz
Priority date: 2018-06-13
Filing date: 2019-06-10
Publication date: 2019-12-19
Also published as: PH12020552147A1; KR20210018314A; CN112313443B; RU2758743C1; CN112313443A; FR3082594A1; FR3082594B1; KR102498803B1

Abstract

The invention relates to a thermally insulating sealed tank which is integrated into a load-bearing structure and in which the secondary sealed membrane (4, 104) includes a plurality of strips made of an alloy having a low coefficient of thermal expansion, while the primary sealed membrane (6, 106) includes metal plates having first parallel corrugations (56, 156) as well as second corrugations (55, 155) that are perpendicular to the first corrugations. A secondary metal beam (30) that runs parallel to the edge (100) has a first planar leg (31) extending parallel to the first load-bearing wall as well as a second planar leg (321, 322) which extends parallel to the second load-bearing wall and onto which an end portion of the secondary sealed membrane (4, 104) is welded. A primary angle part has a metal angle section (42) onto which an end portion of the primary sealed membrane (6, 106) is welded. Holding members (15, 45) retain said primary angle part and penetrate the secondary sealed membrane (4, 104) in a sealed manner.

Description

WATERPROOF AND THERMALLY INSULATING TANK

Technical area

The invention relates to the field of tanks, sealed and thermally insulating, with membranes, for the storage and / or transport of fluid, such as a liquefied gas.

Sealed and thermally insulating tanks with membranes are used in particular for the storage of liquefied natural gas (LNG), which is stored, at atmospheric pressure, at around -163 ° C. These tanks can be installed on the ground or on a floating structure. In the case of a floating structure, the tank may be intended for the transport of liquefied natural gas or to receive liquefied natural gas serving as fuel for the propulsion of the floating structure.

Technological background

Document WO-A-89/09909 discloses a sealed and thermally insulating tank for storing liquefied natural gas arranged in a support structure and the walls of which have a multilayer structure, namely from the outside towards the inside of the tank, a secondary thermally insulating barrier anchored against the supporting structure, a secondary waterproof membrane which is supported by the secondary thermally insulating barrier, a primary thermally insulating barrier which is supported by the secondary waterproof membrane and a primary waterproof membrane which is supported by the thermal barrier primary insulator and which is intended to be in contact with the liquefied natural gas stored in the tank. The primary insulating barrier comprises a set of rigid plates which are held by means of the welding supports of the secondary waterproof membrane.

In one embodiment, the primary waterproof membrane is formed by an assembly of rectangular sheets having corrugations in two perpendicular directions, said sheets being welded together with overlap and being welded by their edges on metal strips fixed in rebates along of the edges of the plates of the primary insulating barrier. EP-A-0064886 describes other sealed and thermally insulating tanks and the angles of these tanks. In a first alternative embodiment of the tank angle, the primary sealing barrier is made of an embossed cryogenic steel sheet. In another alternative embodiment of the angle, the primary sealing barrier consists of a flat invar sheet.

summary

One idea underlying the invention consists in providing a tank wall which combines the advantages of a secondary membrane formed by parallel strakes, the robustness of which has been proven by experience, and of a corrugated primary membrane, which can have very good resistance to accidental indentations and other stresses, resulting for example from thermal contraction, movements of the cargo and / or deformation of the ship's beam at sea.

Another idea underlying the invention is to provide a corner structure for such a tank wall, which is relatively easy to manufacture.

According to one embodiment, the invention provides a sealed and thermally insulating tank integrated into a support structure, the tank comprising a first tank wall fixed to a first support wall and a second tank wall fixed to a second support wall joining the first support wall at an edge of the support structure,

in which each of the first and second tank walls comprises a primary waterproof membrane intended to be in contact with a product contained in the tank, a secondary waterproof membrane arranged between the primary waterproof membrane and the support wall, a primary insulating barrier arranged between the primary waterproof membrane and the secondary waterproof membrane and a secondary insulating barrier arranged between the secondary waterproof membrane and the support wall,

in which the secondary waterproof membrane comprises a plurality of strakes made of alloy with a low coefficient of expansion, a strake comprising a flat central portion resting on an upper surface of the secondary insulating barrier and two raised edges projecting towards the interior of the tank by relative to the central portion, the strakes being juxtaposed and welded together in a leaktight manner raised edges,

wherein the primary waterproof membrane comprises metal plates having first parallel corrugations, second corrugations perpendicular to the first corrugations and planar portions located between the first corrugations and between the second corrugations and resting on an upper surface of the primary insulating barrier.

According to one embodiment, the tank wall comprises a secondary metal beam disposed parallel to the edge and anchored to the first and second load-bearing walls, the metal beam comprising a first plane wing parallel to the first support wall and a second parallel plane wing to the second load-bearing wall, the two flat wings being rigidly connected to each other at a connection zone, each of the first and second flat wings having a receiving portion which extends away from the edge relative to the connection zone and onto which is welded an end portion of the secondary waterproof membrane.

According to one embodiment, the tank wall comprises a primary corner piece, resting on an interior surface of the first and second plane wings of the secondary beam, the primary corner piece comprising a metal angle iron on which a portion is welded. end of the primary waterproof membrane of the first and second tank walls and a rigid insulating part arranged between the metal angle and the secondary beam,

and retaining members retain said primary corner piece to the secondary insulating barrier of the first and second vessel walls or to the first and second load-bearing walls, the retaining members being configured to pass through the secondary waterproof membrane of the first and second second tank walls.

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

The anchoring of the secondary beam to the supporting structure can be carried out in different ways. According to one embodiment, each of the first and second planar wings also has an anchoring portion which extends towards the support structure relative to the connection zone, the anchoring portion of the first flat wing and respectively of the second flat wing being linked to the first bearing wall and respectively to the second supporting wall.

The connection between the anchoring portion of a flat wing and the bearing wall can be achieved in different ways, for example by bolting, welding or the like. According to one embodiment, the first support wall, and respectively the second support wall, carries an anchoring plate disposed at a distance from the edge substantially equal to the thickness of the secondary insulating barrier and the anchoring portion of the first planar wing and respectively of the second planar wing is welded to the anchoring plate, preferably to the surface of the anchoring plate which is remote from the edge.

The secondary insulating barrier can be produced in different ways. According to one embodiment, the secondary insulating barrier comprises a plurality of juxtaposed parallelepipedal secondary insulating panels.

Retaining members can be configured to retain the primary corner piece to the secondary insulating barrier and / or to the load-bearing wall of each of the two vessel walls.

According to one embodiment, a said retaining member comprises a metal rod fixed to an upper surface of a said secondary insulating panel in line with the primary corner piece and projecting through the secondary waterproof membrane to cooperate with the piece rigid insulation.

According to one embodiment, a said retaining member comprises a base fixed to the supporting wall in line with the primary corner piece and a coupler retained by the base and extending through the thickness of the secondary insulating barrier. and the secondary waterproof membrane to cooperate with the rigid insulating part.

Such a coupler may or may not cooperate with the secondary insulating panels. According to one embodiment, said coupler comprises a secondary coupler cooperating with a said secondary insulating panel to retain the secondary insulating panel on the supporting wall and a primary coupler carried by the secondary coupler and cooperating with the rigid insulating part to retain the insulating part rigid. The secondary waterproof membrane can be formed in different ways. According to one embodiment, in at least one said tank wall, a longitudinal direction of the strakes is perpendicular to the edge, the secondary waterproof membrane further comprising a row of end sheets having a flat edge forming the portion of end of the secondary waterproof membrane welded to the secondary beam, the end sheets having raised edges parallel to said longitudinal direction of the strakes and which gradually decrease in the direction of the secondary beam. (Other details of such a membrane are for example described in WO-A-2012072906)

The raised edges of the secondary membrane can be stopped at a greater or lesser distance from the angle of the tank. Preferably, the raised edges continue at least under part of the primary corner piece. Several possibilities exist for this.

According to one embodiment, the rigid insulating part of the primary corner part comprises a plurality of segments juxtaposed in the direction of the edge, and in which the raised edges of the end sheets penetrate into spaces between said juxtaposed segments .

According to one embodiment, the rigid insulating part has grooves made in the longitudinal direction of the strakes on a surface of the rigid insulating part resting on the flat wing of the secondary beam, and in which the raised edges of the end plates penetrate into said grooves.

Thanks to such spacings or grooves, it is possible to continue the raised edges under the primary corner piece up to a distance relatively close to the edge, which improves the flexibility of the secondary membrane in the direction parallel to the 'edge and allows to limit the intensity of the efforts to be taken up at the ends of the edge. The ends of the edge can in particular be trihedral zones located at the intersection of several edges.

According to one embodiment, a first said secondary insulating panel situated between a load-bearing wall and the corresponding flat wing of the secondary beam comprises a cover plate, a bottom plate and spacers developing in the thickness direction of the tank wall between the bottom plate and the cover plate to keep the bottom plate and the cover plate at a distance from each other,

and a second said secondary insulating panel further from the edge than the first secondary insulating panel comprises a cover plate, a bottom plate and a structural insulating foam interposed between the bottom plate and the cover plate so that the plate the cover is kept away from the bottom plate by said structural insulating foam.

Thanks to this arrangement, it is possible to use secondary insulating panels based on structural insulating foam over large portions of the tank wall, to benefit from the best thermal insulation properties of these panels. Secondary insulating panels having spacers developing along the thickness direction are however used near the edge, and possibly in any other zone of the tank wall where the compression stresses are higher, to benefit from the best resistance to the stresses of these panels.

The primary insulating barrier can be produced in different ways. According to one embodiment, the primary insulating barrier comprises a plurality of juxtaposed parallelepipedal primary insulating panels.

According to one embodiment, a said primary insulating panel adjacent to the primary corner piece comprises a cover plate, a bottom plate and a structural insulating foam interposed between the bottom plate and the cover plate so that the plate the cover is kept away from the bottom plate by said structural insulating foam. It is also possible to use primary insulating panels based on structural insulating foam on large portions of the tank wall, to benefit from the better thermal insulation properties of these panels.

The primary waterproof membrane can be formed in different ways. According to embodiments, the first and second undulations can be continuous or discontinuous at the intersections between first and second undulations. According to one embodiment, the first corrugations of the primary waterproof membrane extend perpendicular to the edge, the primary waterproof membrane comprising cap parts welded to the metal angle to close said first corrugations. (The cap part is known for example from WO-A-2014167228).

According to one embodiment, the first corrugations of the primary waterproof membrane extend perpendicular to the edge, the primary waterproof membrane comprising a corrugated corner piece welded to the metal angle to connect a said first corrugation of the first wall of tank to a said first undulation of the second tank wall. (The corrugated corner piece is known for example from FR-A-2739675).

The secondary beam can be manufactured with a greater or lesser length. According to one embodiment, the secondary beam comprises at least two segments of beam juxtaposed along the edge with a spacing and a connecting element disposed in the spacing to join the two beam segments, the connecting element comprising a first planar wing welded astride the first planar wings of the two beam segments and a second planar wing welded astride on the second planar wings of the two beam segments.

Thus, it is possible to manufacture secondary beam in several successive pieces, having for example a length of 1 to 3 m each, which facilitates handling.

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

Such a tank can be part of a terrestrial storage installation, for example to store LNG or be installed in a floating structure, coastal or deep water, in particular an LNG tanker, a floating storage and regasification unit (FSRU) , a floating production and remote storage unit (FPSO) and others.

According to one embodiment, a ship for transporting a cryogenic fluid comprises a double hull and aforementioned tank arranged in the double hull. According to one embodiment, the double shell has an internal shell forming the carrying structure of the tank.

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

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

Brief description of the figures

The invention will be better understood, and other objects, 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 without limitation. , with reference to the accompanying drawings.

- Figure 1 is a sectional view of a tank at an angle formed by two walls, according to a first embodiment.

- Figure 2 is a view similar to Figure 1 showing a second embodiment.

- Figure 3 is a schematic sectional view of a primary corner piece according to one embodiment.

- Figure 4 is a schematic perspective view of a connecting element for a secondary beam of the tank wall.

- Figure 5 is a schematic cutaway view of an LNG tank and a loading / unloading terminal of this tank.

Detailed description of embodiments The vessel wall is attached to the wall of a support structure. By convention, we will call "on" or "above" a position located closer to the inside of the tank and "under" or "below" a position located closer to the supporting structure, whatever the orientation of the tank wall in relation to the earth's gravity field.

In Figure 1, there is shown the multilayer structure of two walls 1 and 101 of a sealed and thermally insulating tank for the storage of a liquefied fluid, such as liquefied natural gas (LNG). Each wall 1, 101 of the tank successively comprises, in the direction of the thickness, from the outside towards the inside of the tank, a secondary thermally insulating barrier 2, 102 retained at a load-bearing wall 3, 103, a membrane secondary waterproof 4, 104 resting against the secondary thermally insulating barrier 2, 102, a primary thermally insulating barrier 5, 105 resting against the secondary waterproof membrane 4, 104 and a primary waterproof membrane 6, 106 intended to be in contact with natural gas liquefied contained in the tank.

The supporting structure can in particular be formed by the hull or double hull of a ship. The support structure comprises a plurality of support walls 3, 103 defining the general shape of the tank, usually a polyhedral shape. The two supporting walls 3 and 103 meet at an edge 100, forming a dihedral angle which could have different values. Here, an angle of 90 ° is shown.

The secondary thermally insulating barrier 2, 102 comprises a plurality of secondary insulating panels 7, 107 which are anchored on the support wall 3, 103 by means of retaining devices 98, 198 known elsewhere. The secondary insulating panels 7, 107 have a generally parallelepiped shape and are arranged in rows parallel to the edge 100. Mastic strands 99, 199 are interposed between the secondary insulating panels 7, 107 and the supporting wall 3, 103 for make up for the deviations of the carrier wall 3, 103 relative to a flat reference surface. Kraft paper can be inserted between mastic strands 99, 199 and the support wall 3, 103 to prevent adhesion of the mastic strands 99, 199 on the support wall 3, 103. The secondary insulating panels 7, 107 can be produced according to different structures known elsewhere.

In a first embodiment, a secondary insulating panel 7, 107 is produced in the form of a box comprising a bottom plate, a cover plate and bearing webs extending, in the thickness direction of the wall 1 of the tank, between the bottom plate and the cover plate and delimiting a plurality of compartments filled with an insulating lining, such as perlite, glass wool or rock wool. In a variant, the supporting sails are replaced by pillars of small section relative to the overall section of the panel. Such a general structure is for example described in WO-A-2012/127141 or WO-A- 2017/103500

In a second embodiment, a secondary insulating panel 7, 107 comprises a bottom plate, a cover plate and possibly an intermediate plate, for example made of plywood. The secondary insulating panel 7, 107 also comprises one or more layers of insulating polymeric foam sandwiched between the bottom plate, the cover plate and the optional intermediate plate and bonded thereto. The insulating polymer foam can in particular be a polyurethane-based foam, optionally reinforced with fibers. Such a general structure is for example described in WO-A- 2017/006044.

Preferably, the secondary insulating panels 7, 107 have different structures depending on their location in the tank wall 1, 101. Thus, secondary insulating panels 7, 107 according to the first embodiment can be used in an end zone of the tank wall 1, 101 located closer to the edge 100 and secondary insulating panels 7, 107 according to the second embodiment can be used in a central zone of the tank wall 1, 101 located further from the edge 100.

The secondary waterproof membrane 4, 104 comprises a continuous sheet of metal strakes, with raised edges. The strakes are welded by their raised edges on parallel welding supports 21, 121 which are fixed in grooves made on the cover plates of the secondary insulating panels 7, 107. The strakes are, for example, made of Invar®: 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 . It is also possible to use alloys of iron and manganese whose coefficient of expansion is typically of the order of 7.10 ⁶ K ¹ . Other details of such a continuous sheet of metal strakes are described for example in WO-A-2012/072906.

The primary thermally insulating barrier 5 comprises a plurality of primary insulating panels 22, 122 having a generally parallelepiped shape. The primary insulating panels 22, 122 can have identical or different lengths and widths than those of the secondary insulating panels 7, 107.

Like the secondary insulating panels 7, 107, the primary insulating panels 22, 122 can be produced according to different structures known elsewhere. Preferably, the primary insulating panel 22, 122 has a multilayer structure similar to the second embodiment of the secondary insulating panel 7, 107.

Preferably, the primary insulating panels 22, 122 are retained at the support structure by couplers not shown, which can serve to jointly retain the primary insulating panels 22, 122 and the underlying secondary insulating panels 7, 107. Such a coupler may include a secondary coupler cooperating with a secondary insulating panel 7, 107 for retaining the secondary insulating panel 7, 107 on the carrier wall 3, 103 and a primary coupler carried by the secondary coupler and cooperating with the primary insulating panel 22 , 122.

Figure 1 also shows that the primary waterproof membrane 6, 106 comprises a continuous sheet of sheet which has two series of mutually perpendicular undulations. The first series of undulations 55, 155 extends perpendicular to the edge 100. The second series of undulations 56, 156 extends parallel to the edge 100. The two series of undulations can have a regular spacing or periodic irregular spacing. In one embodiment, the undulations 55, 155 and 56, 156 are continuous and form intersections between the two series of undulations. In another embodiment, the primary waterproof membrane 6, 106 can also have two series of mutually perpendicular undulations with discontinuities of certain undulations at the intersections between the two series. For example, in this case, the interrupts can be distributed alternately in the first series of undulations and the second series of undulations and, within a series of undulations, the interruptions of a ripple are offset with respect to the interruptions of an adjacent parallel ripple. This offset can be equal to the spacing between two parallel undulations.

The primary waterproof membrane 6, 106 can be formed of rectangular sheet metal plates welded together by forming small overlap zones along their edges, according to the known technique. The primary membrane 6, 106 is fixed to the primary insulating barrier 5, 105 by any suitable means. Metal anchoring strips, not shown, can be fixed to the cover plates of the primary insulating panels 22, 122 at the locations of the contours of the rectangular plates. The edges of the rectangular plates can thus be fixed by welding along the anchoring strips. The anchoring strip is fixed in a countersink on the cover plate by any suitable means, for example screws or rivets.

The structure of the tank at the junction between the two tank walls 1 and 101 will now be more particularly described.

A secondary metal beam 30 is placed parallel to the edge 100 in the thickness of the secondary insulating barrier 2, 102. The secondary beam 30 has a first wing 31, flat, extending parallel to the load-bearing wall 3 and a second flat wing, extending parallel to the load-bearing wall 103. These two wings are assembled at right angles by a welded connection. In the example shown, the second flat wing is formed by two plates 321 and 322 welded on either side of the first wing 31, which can be produced in one piece or also in the form of several plates welded together . The portion of the first wing 31 which extends between the support structure and the welded connection of the two wings is an anchoring portion which is linked to the support wall

103 to take up the tensile force of the secondary membrane 4. In the same way, the plate 321 of the second planar wing is an anchoring portion which is linked to the load-bearing wall 3 to take up the tensile force of the secondary membrane 104. These two anchoring portions can be welded to two anchoring plates 33, 133, preferably on the surface of the anchoring plate 33, 133 which is distant from the edge 100.

The portion of the first wing 31 which extends beyond the welded connection of the two wings is a receiving portion 34 on which the end of the secondary membrane 4 is welded. Likewise, the plate 322 of the second planar wing is a receiving portion on which the end of the secondary membrane

104 is welded.

Sizing example

In one embodiment, the secondary beam 30 is made of metal sheets, for example of invar®, the thickness of which is between 1 and 2 mm, for example 1.5 mm. The anchoring portions of the secondary beam 30 can have the same thickness.

The strakes of the secondary waterproof membrane 4, 104 may have a thickness of less than 1 mm, for example 0.7 mm. The end sheets 25, 125 may have a thickness greater than but less than 1.5 mm, for example 1 mm.

In one embodiment, the primary waterproof membrane 6, 106 has a greater thickness than the secondary waterproof membrane 4, 104, for example 1, 2mm.

The thickness of the anchor plates 33, 133 is for example between 5 and 12mm, in particular around 8 mm.

To make the secondary beam 30 all along the edge 100, it is preferable to use several successive segments, the length of which is adapted to the handling conditions, for example 1 to 3 m per segment. Figure 4 illustrates a connecting element 50 which can be used to assemble two adjacent segments of the secondary beam 30. The connecting element 50 comprises a first planar wing 51 intended to be welded astride the first wing 31 of the two adjacent segments and a second planar wing 52 intended to be welded astride the plate 322 of the two adjacent segments.

In one embodiment, the end of the secondary membrane 4, 104 is formed of a row of end sheets 25, 125 having a flat edge 26, 126 welded to the receiving portion of the secondary beam 30 and the raised edges extending the raised edges of strakes and which gradually decrease towards the flat edge.

The junction between the primary insulating barriers 5 and 105 is carried out by means of a primary corner piece placed on the secondary beam 30. The corner piece comprises an insulating piece 41 in the form of an angle iron having two perpendicular wings, the thickness is substantially equal to the thickness of the primary insulating barriers 5 and 105. A metal angle 42 is fixed on the upper surface of insulating part 41 along the angle. The insulating part 41 can be produced in different ways, for example in solid plywood; in one or more blocks of a sandwich structure made of one or more layers of polymer foam and one or more rigid plates, for example of plywood; or in the form of one or more boxes filled with insulating material.

The end of the primary waterproof membrane 6, 106 is welded to the metal angle 42 in a sealed manner. Several solutions exist for sealing the corrugations 55, 155 perpendicular to the edge 100. In the embodiment of FIG. 1, corrugated corner pieces 43 welded to the metal angle 42 each time connect a corrugation 55 to a corrugation 155. The corrugated corner piece 43 is known for example from FR-A-2739675.

In the embodiment of Figure 2, cap pieces 44, 144 are welded to the metal angle 42 to close the end of the corrugations 55, 155. The cap piece is known for example from WO-A- 2014167228.

To retain the primary corner piece on the secondary membrane 4, 104, FIG. 1 shows two retaining members 15 carried by the insulating panels secondary 7, 107 and cooperating with the insulating part 41. More specifically, the retaining member 15 may comprise a metal plate 16 fixed to the cover plate of the secondary insulating panel 7, 107 and a threaded rod 17 which passes through the secondary membrane 4, 104 and engages in a tapped hole in an insulating part 41 or in a gap between two insulating parts 41. A nut 18 is screwed onto the threaded rod 17 and engages the insulating part 41 or the two insulating parts 41 to clamp it against the secondary membrane 4, 104. At the level of the crossing of the secondary membrane 4, 104, the threaded rod 17 can carry a collar whose periphery is welded to the secondary membrane 4, 104 to ensure sealing. Other details of the retaining members 15 can be found for example in the publication FR-A-2887010.

To limit the thermal bridge caused by the retaining members 15, the threaded rod 17 and the nut 18 are configured to engage a lower part of the insulating part 41, at a distance from the primary waterproof membrane 6, 106. For example the nut 18 engages a bottom panel of the insulating part 41 or a cleat close to this bottom panel. Preferably, the free space necessary for the fitting of the nut 18, for example an access well opening onto the upper face of the insulating part 41, is filled with the aid of an insulating packing 19, for example a plug of polymer foam.

In the embodiment of Figure 2, identical reference numerals designate elements identical or similar to those of Figure 1. In this case, the retaining members 45 retain the primary corner piece directly to the support structure. For this, a retaining member 45 comprises for example a protruding coupler 47, in one or more parts, the base of which is linked to the supporting wall 3, 103, for example by means of a base forming a ball joint, and the end carries in the same way a nut 48 engaging the insulating part 41 or two insulating parts 41 to tighten it against the secondary membrane 4, 104. Other details of the retaining members 45 can be found for example in FR-A -2798358.

Figures 1 and 2 also illustrate different possibilities as to the extent of the raised edges of the secondary membrane 4, 104. In Figure 2, the raised edges end at the inclined edge 49 outside of the part primary angle. The insulating piece 41 therefore rests on the flat wings of the secondary beam 30. In the embodiment of FIG. 1, the raised edges sketched in broken lines extend under the insulating piece 41, for example in grooves made in this one. ci, and can thus get closer to the edge. This results in greater flexibility of the secondary membrane 4, 104 in the direction parallel to the edge 100 and a reduction in the forces to be taken up at the ends of the edge 100.

The insulating part 41 can be made in a single part or several parts. FIG. 3 illustrates an embodiment in which the primary corner piece 60 comprises the angle iron 42 and an insulating piece in three parts. More specifically, two pieces of wood 61 and 62, parallelepiped, are fixed under the two wings of the angle iron 42 and a piece of polymer foam 63 is arranged between the pieces of wood 61 and 62 and glued to them. In this case, the retaining members 15 or 45 are arranged to cooperate with the pieces of wood 61 and 62, while the piece of polymer foam 63 simply performs a thermal insulation function.

The pieces of wood 61 and 62 can also be replaced by blocks of a high density polymer foam (for example greater than 200 kg / m 3), by blocks of a sandwich structure made of one or more layers of polymer foam and one or more rigid plates, for example of plywood; or by boxes filled with insulating material.

With reference to FIG. 5, a cutaway view of an LNG tanker 70 shows a tank 71, sealed and insulated, of generally prismatic shape mounted in the double hull 72 of the ship. The wall of the tank 71 comprises a primary waterproof barrier intended to be in contact with the LNG contained in the tank, a secondary waterproof barrier arranged between the primary waterproof 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 shell 72.

In a manner known per se, loading / unloading lines 73 arranged on the upper deck of the ship can be connected, by means of appropriate connectors, to a maritime or port terminal for transferring a cargo of LNG from or to the tank 71. FIG. 5 represents an example of a maritime terminal comprising a loading and unloading station 75, an underwater pipe 76 and a shore installation 77. The loading and unloading station 75 is a fixed off-shore installation comprising an arm mobile 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 movable arm 74 can be adjusted to suit all LNG carrier sizes . A connection 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 onshore installation 77. This comprises liquefied gas storage tanks 80 and connection pipes 81 connected by the submarine pipe 76 to the loading or unloading station 75. The submarine pipe 76 allows the transfer of liquefied gas between the loading or unloading station 75 and the shore installation 77 over a long distance, for example 5 km, which makes it possible to keep the LNG carrier 70 at a great distance from the coast during the 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 include", "to understand" or "to include" and its conjugated forms does not exclude the presence of other elements or steps than those stated in a claim.

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

Claims

1. Watertight and thermally insulating tank integrated in a support structure, the tank comprising a first tank wall (1) fixed on a first support wall (3) and a second tank wall (101) fixed on a second support wall (103 ) joining the first support wall at an edge (100) of the support structure,

wherein each of the first and second tank walls comprises a primary waterproof membrane (6, 106) intended to be in contact with a product contained in the tank, a secondary waterproof membrane (4, 104) arranged between the primary waterproof membrane and the supporting wall, a primary insulating barrier (5, 105) arranged between the primary waterproof membrane and the secondary waterproof membrane and a secondary insulating barrier (2, 102) arranged between the secondary waterproof membrane and the supporting wall,

in which the secondary waterproof membrane (4, 104) comprises a plurality of strakes of alloy with a low coefficient of expansion, a strake comprising a flat central portion resting on an upper surface of the secondary insulating barrier and two raised edges projecting towards the inside the tank with respect to the central portion, the strakes being juxtaposed and welded together in a leaktight manner at the raised edges,

in which the primary waterproof membrane (6, 106) comprises metal plates having first corrugations (56, 156) parallel, second corrugations (55, 155) perpendicular to the first corrugations and planar portions located between the first corrugations and between the second undulations and resting on an upper surface of the primary insulating barrier, the tank wall comprising a secondary metal beam (30) disposed parallel to the edge (100) and anchored to the first and second load-bearing walls (3, 103), the metal beam comprising a first plane wing (31) parallel to the first support wall and a second plane wing (321, 322) parallel to the second support wall, the two plane wings being rigidly connected to each other at level 'a connecting zone, each of the first and second planar wings having a receiving portion (34, 322) which extends away from the edge p ar compared to connection area,

the tank wall comprising a primary corner piece comprising a metal angle (42) on which is welded an end portion of the primary waterproof membrane (6, 106) of the first and second tank walls and a rigid insulating piece ( 41; 61, 62, 63) arranged between the metal angle (42) and the secondary beam (30),

characterized by the fact that an end portion of the secondary waterproof membrane (4, 104) is welded to said receiving portion of each of the first and second planar wings,

the primary corner piece resting on an inner surface of the first and second plane wings of the secondary beam (30),

and that retaining members (15, 45) retain said primary corner piece to the secondary insulating barrier (2, 102) of the first and second tank walls or to the first and second load-bearing walls (3, 103), the members retaining means (15, 45) being configured to sealingly pass through the secondary waterproof membrane (4, 104) of the first and second vessel walls.

2. Tank according to claim 1, wherein each of the first and second planar wings further has an anchoring portion (321) which extends towards the support structure relative to the connection zone, the anchoring portion of the first planar wing and respectively of the second planar wing being linked to the second support wall and respectively to the first support wall.

3. Tank according to any one of claims 1 to 2, wherein the secondary insulating barrier comprises a plurality of secondary insulating panels (7, 107) parallelepipedal juxtaposed, and a said retaining member (15) comprises a metal rod (17 ) fixed to an upper surface of a said secondary insulating panel (7, 107) in line with the primary corner piece and projecting through the secondary waterproof membrane (4, 104) to cooperate with the rigid insulating piece (41 ).

4. Tank according to any one of claims 1 to 3, wherein a said retaining member (45) comprises a base fixed to the carrier wall to the right of the primary corner piece and a coupler (47) retained by the '' base and extending through the thickness of the secondary insulating barrier (2, 102) and the secondary waterproof membrane to cooperate with the rigid insulating part (41).

5. Tank according to claim 4, wherein the secondary insulating barrier comprises a plurality of secondary insulating panels (7, 107) juxtaposed parallelepipedic, and wherein said coupler (47) comprises a secondary coupler cooperating with a said secondary insulating panel to retain the secondary insulating panel on the supporting wall and a primary coupler carried by the secondary coupler and cooperating with the rigid insulating part (41) to retain the rigid insulating part (41).

6. Tank according to any one of claims 1 to 5, in which, in at least one said wall of the tank, a longitudinal direction of the strakes is perpendicular to the edge (100), the secondary waterproof membrane further comprising a row of end sheets (25, 125) having a flat edge (26, 126) forming the end portion of the secondary waterproof membrane welded to the secondary beam (30), the end sheets having raised edges parallel to said longitudinal direction of strakes and which gradually decrease in the direction of the secondary beam (30).

7. Tank according to claim 6, in which the rigid insulating part (41) of the primary corner part comprises a plurality of segments juxtaposed in the direction of the edge, and in which the raised edges of the end sheets ( 25, 125) penetrate into spaces between said juxtaposed segments.

8. Tank according to claim 6 or 7, wherein the rigid insulating part (41) has grooves formed in the longitudinal direction of the strakes on a surface of the rigid insulating part resting on the flat wing of the secondary beam (30) , and in which the raised edges of the end sheets (25, 125) penetrate into said grooves.

9. Tank according to any one of claims 1 to 8, in which the secondary insulating barrier comprises a plurality of juxtaposed parallelepipedal secondary insulating panels (7, 107),

wherein a first said secondary insulating panel (7, 107) located between a load-bearing wall and the corresponding flat wing of the secondary beam comprises a plate cover plate, a bottom plate and spacers developing along the thickness direction of the vessel wall between the bottom plate and the cover plate to keep the bottom plate and the cover plate, and in which a second said secondary insulating panel (7, 107) further from the edge than the first secondary insulating panel comprises a cover plate, a bottom plate and a structural insulating foam interposed between the bottom and the cover plate so that the cover plate is kept away from the bottom plate by said structural insulating foam.

10. Tank according to any one of claims 1 to 9, in which the primary insulating barrier comprises a plurality of primary insulating panels (22, 122) juxtaposed parallelepiped,

wherein a said primary insulating panel adjacent to the primary corner piece has a cover plate, a bottom plate and a structural insulating foam interposed between the bottom plate and the cover plate so that the cover plate is held spaced from the bottom plate by said structural insulating foam.

1 1. A tank according to any one of claims 1 to 10, in which the first undulations (55, 155) of the primary waterproof membrane (6, 106) extend perpendicular to the edge (100), the waterproof membrane primer comprising cap parts (44, 144) welded to the metal angle (42) to close said first corrugations.

12. Tank according to any one of claims 1 to 1 1, wherein the first corrugations (55, 155) of the primary waterproof membrane (6, 106) extend perpendicular to the edge, the primary waterproof membrane comprising a corrugated corner piece (43) welded to the metal angle (42) to connect a said first corrugation (55) of the first tank wall to a said first corrugation (155) of the second tank wall.

13. Tank according to any one of claims 1 to 12, wherein the secondary beam (30) comprises at least two segments of beam juxtaposed along the edge with a spacing and a connecting element (50) disposed in the spacing for joining the two beam segments, the element connecting comprising a first plane wing (51) welded astride the first planar wings of the two beam segments and a second plane wing (52) welded astride the second plane wings of the two beam segments.

14. Ship (70) for transporting a fluid, the ship comprising a double hull (72) and a tank (71) according to any one of claims 1 to 13 disposed in the double hull (72).

15. A method of loading or unloading a ship (70) according to claim 14, 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 vessel (71).

16. Transfer system for a fluid, the system comprising a vessel (70) according to claim 14, insulated pipes (73, 79, 76, 81) arranged so as to connect the tank (71) installed in the hull of the vessel to a floating or terrestrial storage installation (77) and a pump for driving a fluid through the insulated pipes from or to the floating or terrestrial storage installation to or from the vessel of the ship.