Sealed and thermally insulating tank

Abstract

A sealed and thermally insulating tank comprises a tank wall comprising a secondary insulating barrier (1), a secondary sealed membrane (2), a primary insulating barrier (3) and a primary sealed membrane (4) . A plurality of primary anchoring members (12) interact with at least one primary insulating panel (11) of the primary insulating barrier (3). A said primary anchoring member (12) comprises a base (30), a stem (31) passing through an opening in the secondary sealed membrane (2), a bearing element (16, 54) mounted on the stem (31) and bearing on a primary insulating panel (11), a sealing washer (34) engaged on the stem (31) and comprising a collar (37) secured sealingly to the secondary sealed membrane (2), and a deformable seal (42) sealingly connecting said sealing washer (34) and the stem in such a way as to allow a relative movement between the sealing washer (34) and the stem.

Description

Watertight and thermally insulated tank

[0001] The invention relates to the field of leak-proof and thermally insulated membrane tanks. In particular, the invention relates to the field of leak-proof and thermally insulated tanks for the storage and / or transport of liquefied gases at low temperatures, such as tanks for transporting Liquefied Petroleum Gas (LPG) at temperatures ranging, for example, from -50°C to 0°C, or for transporting Liquefied Natural Gas (LNG) at approximately -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 can be used for transporting liquefied gas or for receiving liquefied gas to serve as fuel for the propulsion of the floating structure.

[0002] In one embodiment, the liquefied gas is LNG, namely a mixture with a high methane content stored at a temperature of approximately -162°C at atmospheric pressure. Other liquefied gases can also be considered, including ethane, propane, butane, or ethylene. Liquefied gases can also be stored under pressure, for example, at a relative pressure between 2 and 20 bar, and in particular at a relative pressure close to 2 bar. Technological background

[0003] Document WO2014096600 discloses a sealed and thermally insulated liquefied natural gas storage tank arranged in a load-bearing structure and whose walls have a multi-layered structure, namely from the outside to the inside of the tank, a secondary thermally insulating barrier anchored against the load-bearing structure, a secondary sealed membrane which is supported by the secondary thermally insulating barrier, a primary thermally insulating barrier which is laid on the secondary sealed membrane and a primary sealed 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.

[0004] Each primary and secondary thermal insulation barrier comprises a set of insulating panels, respectively primary and secondary, generally parallelepiped in shape, which are placed side by side to form a support surface for a respective waterproof membrane. The insulating panels are anchored to the load-bearing structure by means of anchoring devices that are fixed to the load-bearing structure and positioned at the corners of the primary and secondary insulating panels. Each anchoring device thus engages with the corners of four adjacent secondary insulating panels and with the corners of four adjacent primary insulating panels to secure them against the load-bearing structure.

[0005] Document WO2013104850 describes a watertight and thermally insulated tank with a multilayer structure in which the corners of the primary thermal barrier insulation panels are not aligned with the corners of the secondary thermal barrier insulation panels. In such a tank, primary anchoring devices cooperating with the primary insulation panels are fixed to a plate anchored to a secondary insulation panel. Thus, the primary anchoring devices and the primary insulation panels are anchored to the load-bearing structure via the secondary insulation panels.

[0006] In all cases, secondary insulation panels are susceptible to deformation and / or displacement. Indeed, secondary insulation panels are subjected to thermal gradients which, due to differential contraction, can cause them to bend. Furthermore, deformation of the supporting structure causes deformation and / or displacement of the secondary insulation panels. This is particularly true when the supporting structure is formed by the internal hull of a floating structure. Moreover, if this structure delineates ballast compartments, the movement of ballast fluid within these compartments can also cause significant deformation of the supporting structure and, consequently, deformation and / or displacement of the secondary insulation panels anchored to it.

[0007] Furthermore, the movement of the liquid within the tank can generate stresses on the primary waterproofing membrane, particularly if it has protruding parts such as corrugations. These stresses are transmitted to the primary insulation panels to which the primary waterproofing membrane is anchored and tend to displace the primary insulation panels laterally. This results in stress concentrations at the primary anchoring devices.

[0008] However, to ensure the watertightness of the secondary waterproofing membrane, the primary anchoring devices include a collar welded watertight to the secondary waterproofing membrane. This collar is rigidly fixed to a stud carrying a support element that interacts with the corresponding primary insulation panel(s). During deformations and / or displacements of the secondary insulation panels and / or displacements of the primary insulation panels, this connection between the primary anchoring devices and the secondary waterproofing membrane can lead to stress concentration at the weld between the collar and the secondary waterproofing membrane, potentially causing damage to both the weld and the secondary waterproofing membrane.

[0009] In particular, when primary anchors are fixed to a secondary insulation panel, deformation and / or displacement of the secondary insulation panels cause displacement of the primary anchor. This displacement of the primary anchor is transmitted to the collar, which is rigidly fixed to the stud, and generates stresses at the watertight connection between the collar and the secondary waterproofing membrane. Such stresses can degrade the secondary waterproofing membrane and / or the watertight connection between the collar and the secondary waterproofing membrane, thereby compromising the watertightness of the secondary waterproofing membrane. Summary

[0010] One key idea of ​​the invention is to limit stress concentrations at the connections between the secondary waterproofing membrane and the primary anchoring element of the primary insulation panels. Another key idea is to create a flexible, watertight connection between the primary anchoring element and the secondary waterproofing membrane. Thus, one key idea is to allow relative movement between the secondary waterproofing membrane and the primary anchoring element. Another key idea is to allow this movement whether the primary anchoring element is anchored directly to the load-bearing structure, for example, by being integrated with the secondary anchoring element, or indirectly, for example, by being attached to a secondary insulation panel.Thus, another idea underlying the invention is to allow relative movement between a secondary insulating panel on which a primary anchoring device is fixed and the secondary waterproof membrane.

[0011] According to one embodiment, the invention provides a sealed and thermally insulating tank comprising a tank wall, the tank wall comprising, successively from the outside of the tank to the inside of the tank along a thickness direction of the tank wall, a secondary insulating barrier intended to be anchored to a load-bearing wall, a secondary waterproof membrane resting on the secondary insulating barrier, a primary insulating barrier resting on the secondary waterproof membrane and a primary waterproof membrane resting on the primary insulating barrier and intended to be in contact with a product contained inside the tank, the primary insulating barrier comprising a plurality of juxtaposed primary insulating panels, the tank further comprising a plurality of primary anchoring elements intended to be retained, directly or indirectly, on the load-bearing wall.each of said primary anchoring devices cooperating with at least one primary insulating panel of the plurality of primary insulating panels so as to retain said at least one primary insulating panel on the secondary waterproofing membrane, wherein one, several or each of said primary anchoring devices comprises: - a base intended to be retained, directly or indirectly, on the load-bearing wall, - a rod extending along the thickness direction of the tank wall from said base towards the primary waterproofing membrane, said rod passing through an opening in the secondary waterproofing membrane, - a bearing element mounted on the rod, said bearing element bearing on a primary insulating panel so as to retain said primary insulating panel on the secondary waterproofing membrane, - a sealing washer engaged on the rod between the bearing element and the opening in the secondary waterproofing membrane, the sealing washer having a central opening through which the rod passes.the sealing washer being fixed in a hermetic manner to the secondary sealing membrane, for example by a collar of the sealing washer, around the orifice of said secondary sealing membrane, - a deformable seal connecting said sealing washer and the rod in such a way as to allow relative movement between the sealing washer and the rod..

[0012] Thanks to these characteristics, relative movement between the secondary waterproofing membrane and the primary anchoring device is possible without risk of damage to the secondary waterproofing membrane or the watertight seal between the primary anchoring device and the secondary waterproofing membrane. In particular, the deformable seal creates a watertight and flexible connection between the rod of the primary anchoring device and the sealing washer that ensures the watertightness of the secondary waterproofing membrane. Such a primary anchoring device thus allows relative movement between the secondary and / or primary insulation panels and the secondary waterproofing membrane without risk of damage to the secondary waterproofing membrane or the seal between the primary anchoring device and said secondary waterproofing membrane.

[0013] According to embodiments, such a tank may include one or more of the following characteristics.

[0014] The primary anchoring device described above can be used on an entire tank wall or only in localized portions of the tank wall such as ballast areas. In one embodiment, the tank wall has a vertical component defining a height of said tank wall in the direction of Earth's gravity, the tank wall comprising several of said primary anchoring devices, each comprising a base, a rod, a bearing element, a sealing washer and a deformable seal as described above, said several primary anchoring devices being arranged on a lower portion of the tank wall, for example at least the lower two-thirds of the height of said tank wall.

[0015] In one embodiment, the tank wall is a first tank wall, the tank further comprising a second tank wall, the first and second tank walls forming a tank edge, the first tank wall comprising several primary anchoring elements, each comprising a base, a rod, a support element, a sealing washer, and a deformable seal as described above, said several primary anchoring elements being arranged at a distance from the tank edge less than a predefined threshold. For example, the predefined threshold corresponds to the width of five insulation panels, said several primary anchoring elements being arranged, for example, to retain five successive primary insulation panels in a direction perpendicular to the edge.

[0016] The lower sections of the tank walls are subject to particularly significant stresses, due, for example, to the weight of the transported liquid or, in the case of transverse tank walls anchored to cofferdam walls, to the ship's ballast. Similarly, the tank's edge areas are also subject to particularly significant stresses, including the pressure generated by the water in the ship's ballast. These stresses can generate relative displacements between the primary and / or secondary insulating barrier and the secondary watertight membrane at the lower section of the tank and / or the tank edges.Thus, thanks to the arrangement of said primary anchoring devices, the risks of degradation of the secondary waterproof membrane are limited due to the flexibility of the connection between said primary anchoring devices and the secondary waterproof membrane.

[0017] Primary insulation panels can be manufactured in various ways. According to one embodiment, primary insulation panels are parallelepiped in shape.

[0018] According to one embodiment, the primary insulating panels comprise a base plate, a cover plate and an insulating lining interposed between the base plate and the cover plate.

[0019] The support element can bear on various portions of the primary insulation panels. In one embodiment, the support element bears directly on the primary insulation panel, for example, by bearing on the backing plate of the primary panel. In another embodiment, the support element bears indirectly on the primary insulation panel, for example, via a shim inserted between the support element and an element of the primary insulation panel, such as the backing plate of the primary insulation panel.

[0020] In one embodiment, the corners of the primary insulating panels have recesses, these recesses providing a bearing surface facing the interior of the tank. In another embodiment, the bearing element of the primary anchoring device bears, directly or indirectly, on the bearing surface of the primary insulating panel. In another embodiment, these recesses are formed in the cover plate and the insulating lining. In another embodiment, the bearing surface is formed by a portion of the base plate extending beyond the recess formed in the insulating lining and the cover plate. In another embodiment, the bearing surface is formed by a wedge placed between the bearing element and a portion of the base plate extending beyond the recess formed in the insulating lining and the cover plate.

[0021] According to one embodiment, a said primary anchoring member cooperates with the corners of adjacent primary insulating panels, for example four panels whose corners are adjacent, so as to anchor said adjacent primary panels to the load-bearing wall.

[0022] The sealing washer can be attached to the secondary waterproofing membrane in various ways. In one embodiment, the sealing washer or collar is welded watertight to the secondary waterproofing membrane.

[0023] According to one embodiment, the deformable seal is deformable along a thickness direction of the tank wall so as to allow the sealing washer to slide along the rod along a thickness direction of the tank wall.

[0024] In one embodiment, the central orifice of the sealing washer has a transverse dimension greater than the transverse dimension of a portion of the rod engaged in said central orifice, so as to allow the rod to move within said central orifice of the sealing washer in a direction perpendicular to the thickness direction of the tank wall. Such a sealing washer allows freedom of movement of the sealing washer relative to the rod in a direction perpendicular to the thickness direction of the tank wall. More specifically, such a primary anchoring element allows displacement of the watertight connection between the sealing washer and the secondary watertight membrane relative to the bearing element mounted on the rod and cooperating with the primary insulation panel(s).Thus, any displacements of the secondary and / or primary insulating panels in a plane perpendicular to the thickness direction of the tank wall are not transmitted to the secondary sealing membrane via the primary anchoring device, thereby reducing stresses related to differential contraction, deformation of the load-bearing wall or liquid movements in the tank, and limiting the risk of degradation of the secondary sealing membrane or of the sealing connection between the sealing washer and the secondary sealing membrane.

[0025] According to one embodiment, the primary anchoring member further comprises a stop carried by the rod, said stop being arranged on the rod between the support element and the sealing washer, the stop having a stop surface opposite the sealing washer in order to stop a movement towards the primary sealing membrane along the thickness direction of the tank wall of said sealing washer relative to the rod.

[0026] Thanks to these characteristics, deformations of the secondary sealing membrane along the thickness direction of the tank wall are limited at the watertight connection between the sealing washer and the orifice of the secondary sealing membrane. In particular, in the event of overpressure in the secondary insulating barrier or deformation of the secondary insulating barrier, deformation of the secondary sealing membrane is prevented along the thickness direction of the tank wall. Indeed, since the sealing washer is hermetically sealed to the secondary sealing membrane around the orifice of the secondary sealing membrane, in the presence of a force tending to displace the secondary sealing membrane towards the interior of the tank, the local deformation of the secondary sealing membrane at the watertight connection with the sealing washer is blocked by the sealing washer's bearing against the bearing surface.This reduces the risk of damage to the secondary waterproofing membrane, for example through punctures. Furthermore, limiting local deformations of the secondary waterproofing membrane reduces the risk of damage to the deformable joint.

[0027] In one embodiment, the rod has a shoulder, said shoulder projecting laterally from the rod, that is, in a direction perpendicular to the longitudinal direction of the rod, beyond the central opening of the sealing washer, such that an external face of said shoulder forms the stop surface. Such a stop is simple to manufacture without requiring any additional parts.

[0028] In one embodiment, the primary anchoring member further comprises a bell mounted on the stem, said bell having a mounting portion and a protective portion, the mounting portion having a central passage through which the stem passes, the protective portion extending along the thickness direction of the tank wall from the mounting portion towards the flange of the sealing washer, the protective portion being hollow, the deformable seal being partially or totally housed within the protective portion. Such a bell surrounding the stem of the primary anchoring member protects both the stem and the deformable seal.

[0029] According to one embodiment, the bell mounting portion comprises a plate extending in a plane perpendicular to the thickness direction of the tank wall, said plate comprising the passage through which the bell passes.

[0030] In one embodiment, the deformable seal is fully housed within the protective portion of the bell. Thus, the deformable seal is protected by the bell, for example, during the assembly of the primary anchoring element in the tank. In another embodiment, the deformable seal is fixed to the rod between the passage of the bell's mounting portion and the sealing washer.

[0031] According to one embodiment, the end of the protective portion opposite the mounting portion of the bell has a rim extending radially outwards, an external face of said rim forming the stop surface in order to stop a movement of the sealing washer along the thickness direction of the tank wall.

[0032] According to one embodiment, an external end of the protective portion opposite the mounting portion forms the stop surface opposite the sealing washer in order to stop a movement of the sealing washer along the thickness direction of the tank wall.

[0033] In one embodiment, the bell is fixed to the rod. The stop surface can thus be formed by the protective portion, which has a fixed position relative to the rod and prevents the sealing washer from moving relative to the rod. In another embodiment, the mounting portion of the bell is welded to the rod.

[0034] In one embodiment, the deformable seal comprises a deformable bellows, said bellows being hollow and extending around and axially along the stem, a first axial end of said bellows being sealed to the stem and a second axial end of said bellows being sealed to the sealing washer. Such a deformable seal in the form of a bellows is simple to manufacture and allows for satisfactory sealing deformation of said seal. Such a bellows can be made of many materials. In one embodiment, the bellows is made of stainless steel. Such a stainless steel bellows is sufficiently thin to allow for elastic deformation. In another embodiment, the bellows is made of stainless steel with a thickness between 0.1 mm and 0.5 mm, for example, between 0.1 mm and 0.3 mm.

[0035] According to one embodiment, the bellows has a plurality of folds having an identical or increasing diameter, a central portion of the bellows formed by said plurality of folds thus having a substantially cylindrical shape of revolution.

[0036] According to one embodiment, the bellows has at least three folds or waves, preferably between three and thirty-two folds, ideally between six and twenty-four folds.

[0037] According to one embodiment, the bellows is flared in shape, the second axial end of the bellows fixed on the sealing washer having a circumferential dimension greater than the circumferential dimension of the first axial end of the bellows fixed on the rod.

[0038] In one embodiment, the bellows has a plurality of folds whose diameter increases from the end anchored to the rod to the end anchored to the sealing washer. Thus, the portion of the bellows formed by these folds has a conical shape, the largest dimension of which is located at the end fixed to the sealing washer.

[0039] In one embodiment, the sealing washer has an internal surface extending in a plane perpendicular to the thickness direction of the tank wall. In another embodiment, the internal surface is arranged opposite the stop surface so as to cooperate with said stop surface, which is, for example, part of the bell or the rod, to prevent the sealing washer from moving relative to the rod along the thickness direction of the tank.

[0040] According to one embodiment, the deformable seal is fixed on the internal surface of the sealing washer, for example on a radially external portion of the internal surface of the sealing washer.

[0041] In one embodiment, the sealing washer has a rib projecting from its inner surface, with the deformable seal being securely fixed to this rib. In another embodiment, the rib of the sealing washer extends from a radially internal portion of its inner surface.

[0042] According to one embodiment, the tank comprises a plurality of secondary anchoring devices, each secondary anchoring device being intended to be anchored to the load-bearing wall and cooperating with the secondary insulating barrier so as to exert a bearing on said secondary insulating barrier in the direction of the load-bearing wall when said secondary anchoring device is anchored to said load-bearing wall.

[0043] According to one embodiment, the base of the primary anchoring member is anchored on a secondary anchoring member.

[0044] In one embodiment, the base of the primary anchoring element is rigidly anchored in the secondary insulating barrier. In this case, the primary anchoring element is retained on the load-bearing wall via the secondary insulating barrier.

[0045] In one embodiment, the secondary insulating barrier comprises a plurality of juxtaposed secondary insulating panels. In one embodiment, one, several, or each secondary insulating panel comprises a base plate, a cover plate, and an insulating gasket sandwiched between the base plate and the cover plate, the secondary waterproof membrane resting on an inner face of the cover plate opposite the insulating gasket. In one embodiment, one, several, or each secondary insulating panel comprises an intermediate plate sandwiched between the cover plate and the base plate of said secondary insulating panel, the insulating gasket of said secondary insulating panel comprising an external insulating gasket sandwiched between the base plate and the intermediate plate and an internal insulating gasket sandwiched between the intermediate plate and the cover plate.

[0046] In one embodiment, the secondary insulating barrier comprises an anchoring plate, the base of the primary anchoring element being anchored to said anchoring plate. In another embodiment, the anchoring plate is housed in a recess formed in the cover plate of a secondary insulating panel, the anchoring plate having an inner surface flush with the inner face of the cover plate.

[0047] According to one embodiment, the anchor plate has a threaded hole and the base has a threaded external end, the base of the primary anchoring member being anchored on the anchor plate by screwing the threaded end of the base into the threaded hole of the anchor plate.

[0048] According to one embodiment, an internal end of the rod opposite the base is threaded, and the primary anchoring member further comprises a nut screwed onto said threaded internal end, the support element being interposed between said nut and the base of the primary anchoring member.

[0049] According to one embodiment, the deformable seal is interposed between the support element and the sealing washer.

[0050] According to one embodiment, one or more elastic washers are inserted between the nut and the support element.

[0051] According to one embodiment, the primary anchoring member has an anchoring shoulder projecting laterally from the stem, said anchoring shoulder forming an anchoring surface developing in a plane perpendicular to the thickness direction, said anchoring surface being turned towards the support element, the deformable seal being fixed in a watertight manner on said anchoring surface.

[0052] According to one embodiment, the inner end of the deformable joint fixed on the rod is interposed between the mounting portion of the bell and the flat anchoring surface of the anchoring shoulder.

[0053] In one embodiment, the bell has freedom of movement along the thickness direction of the tank wall. In another embodiment, the bell's freedom of movement is limited on the one hand by the nut mounted on the rod, or where applicable, the spring washer(s), and, on the other hand, by the anchoring surface of the anchoring shoulder.

[0054] According to one embodiment, the internal axial end of the deformable joint fixed on the rod is interposed between the anchoring surface of the anchoring shoulder and the nut mounted on the rod, or where applicable the elastic washers.

[0055] According to one embodiment, the secondary waterproof membrane and / or the primary waterproof membrane is made of an iron-nickel alloy, for example an alloy whose coefficient of expansion is typically between 1.2 x 10 -6 and 2.10 -6 K -1According to one embodiment, the secondary waterproof membrane and / or the primary waterproof membrane is made of an iron and manganese alloy, for example, whose coefficient of expansion is typically on the order of 7 to 9 x 10⁻¹². -6 K -1 According to one embodiment, the secondary waterproof membrane and / or the primary waterproof membrane comprises a plurality of strakes with raised edges juxtaposed and welded two by two by their raised edges.

[0056] In one embodiment, the primary and / or secondary waterproof membrane comprises a plurality of metal plates, preferably rectangular, welded together. In another embodiment, the primary and / or secondary waterproof membrane comprises a first series of parallel corrugations extending in a first direction and a second series of parallel corrugations extending in a second direction, said first and second directions intersecting.

[0057] In one embodiment, a transfer wedge is arranged around the bell in a gap between the bell and the adjacent primary insulating rings, for example, between the bell and the base plates of said adjacent primary insulating panels. Thanks to these features, a lateral displacement of an insulating panel cooperating with the anchoring element is transmitted via the transfer wedge to the bell, to the rod, and then to the rod support, for example, the secondary insulating barrier, thus allowing the lateral force exerted by the primary insulating panel to be absorbed without risk of degradation of the watertight seal between the sealing washer and the waterproof membrane.

[0058] In one embodiment, the transfer wedge has a thickness, measured along the thickness direction of the tank wall, that is less than the thickness of the base plate of the primary insulating panel. Thus, during lateral movement of the primary insulating panel, only the base plate is brought against the transfer wedge, ensuring good force transmission between the primary insulating panel and the transfer wedge.

[0059] According to one embodiment, the transfer wedge comprises an external portion and a plate, the external portion extending around the sealing washer in the thickness direction of the tank wall, the plate having a central orifice surrounding the bell, the external portion and the plate forming a housing in which the sealing washer is housed with a clearance, so that the wedge can transmit a lateral force to the bell without interfering with the sealing washer.

[0060] According to one embodiment, the transfer wedge further comprises an internal portion extending from the platform and surrounding the bell.

[0061] In one embodiment, the external portion of the transfer wedge is circular cylindrical. In another embodiment, said external portion is coaxial with the rod.

[0062] In one embodiment, the transfer wedge comprises one, preferably several, wings extending radially from the outer portion of the transfer wedge and parallel to the thickness direction of the tank wall. In another embodiment, said wing(s) are housed between two adjacent primary insulating panels.

[0063] In one embodiment, the transfer wedge is smaller than the available spacing between the panels. This facilitates the installation of the wedge between the panels.

[0064] In one embodiment, the sealing washer has a flat surface and the bell has a flat surface, these flat surfaces being configured to be engaged by a screw tool that allows the stem and the sealing washer to be rotationally locked without twisting the deformable joint during the screwing operation of the anchoring element into its support, for example, into the secondary insulating barrier. In another embodiment, the sealing washer has a flat surface and the stem has a flat surface, these flat surfaces being able to be engaged by a screw tool that allows the stem and the sealing washer to be rotationally locked without twisting the deformable joint.

[0065] Such a tank can be part of an onshore storage facility, for example for storing LNG, or be installed in a floating structure, whether coastal or deep-water, including an LNG carrier, a floating storage and regasification unit (FSRU), a floating production and storage unit (FPSO), and others. Such a tank can also serve as a fuel tank in any type of vessel.

[0066] According to one embodiment, the invention also provides a vessel for the transport of a cold liquid product comprising a double hull and a aforementioned tank disposed in the double hull.

[0067] According to one embodiment, the invention also provides a method for loading or unloading such a vessel, in which a cold liquid product is conveyed through insulated pipes from or to a floating or land-based storage facility to or from the vessel's tank.

[0068] 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 to connect the tank installed in the hull of the vessel to a floating or land-based storage facility, and a pump to drive a flow of cold liquid product through the insulated pipes from or to the floating or land-based storage facility to or from the vessel's tank. Brief description of the figures

[0069] The invention will be better understood, and other objects, details, features and advantages thereof will become more apparent from 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.

[0070] Figure 1 is a partial cutaway top view of a sealed and thermally insulating tank wall in which the primary sealed membrane is not shown;

[0071] Figure 2 is a cross-sectional view of the tank wall of Figure 1 along the section plane AA illustrated in Figure 1;

[0072] Figure 3 is a detail view of area B of Figure 2 illustrating a primary anchoring device anchoring two adjacent primary insulating panels;

[0073] Figure 4 is a schematic perspective view of the anchoring device of Figure 3;

[0074] Figure 5 is a schematic perspective view of the primary anchoring element illustrated in Figure 4 in which the bell is not shown;

[0075] Figure 6 is a cross-sectional view of a second embodiment of the primary anchoring element;

[0076] Figure 7 is a cross-sectional view of a third embodiment of the primary anchoring element;

[0077] Figure 8 is a cross-sectional view of a primary anchoring element according to a fourth embodiment;

[0078] Figure 9 is a schematic cutaway representation of a tank on an LNG carrier and a loading / unloading terminal for this tank;

[0079] Figure 10 is a schematic perspective view of a primary anchoring element according to a fifth embodiment;

[0080] Figure 11 is a cross-sectional view of the primary anchoring element of Figure 10 cooperating with the two primary insulating panels;

[0081] Figure 12 is a schematic perspective view of the anchoring device of Figure 11;

[0082] Figure 13 is a cross-sectional view of a primary anchoring element according to a sixth embodiment, the primary anchoring element comprising a transfer wedge;

[0083] Figure 14 is a top view of the primary anchoring element of Figure 13;

[0084] Figure 15 is a schematic perspective view with cross-section of a portion of secondary thermally insulating barrier on which rests a portion of secondary waterproof membrane, the secondary thermally insulating barrier comprising an anchor plate intended to receive a primary anchoring element;

[0085] Figure 16 is a schematic perspective view of part of a primary anchoring element and a mounting tool for said part of the primary anchoring element on the anchoring plate of the secondary thermally insulating barrier of Figure 15;

[0086] Figure 17 is a schematic perspective view with cross-section of the primary anchoring member of Figure 16 after mounting on the anchoring plate of the secondary thermally insulating barrier and addition of a bell.

[0087] In the remainder of this description, the terms "external" and "internal" will be used to designate, according to the definitions given in the description, the relative position of one element with respect to another, with reference to the inside of the tank. Thus, an element close to or facing the inside of the tank is described as internal, as opposed to an external element located close to or facing the outside of the tank. Similarly, the expressions "radially peripheral" or "radially external" characterize the portion far from an axis defining a circular element, as opposed to the expression "radially internal," which characterizes the portion close to said axis. Furthermore, the term "transverse" is used to describe a displacement or a direction of development of an element along a direction located in a plane perpendicular to the thickness direction of the tank wall.

[0088] A sealed and thermally insulated tank for storing a liquefied fluid, such as liquefied natural gas (LNG), comprises a plurality of tank walls with a multilayer structure. Figures 1 and 2 illustrate a portion of such a sealed and thermally insulated tank wall. In these figures, the tank wall comprises, successively, in the thickness direction from the outside to the inside of the tank, a secondary thermally insulating barrier, hereafter referred to as secondary insulating barrier 1, attached to a load-bearing wall (not shown), a secondary sealed membrane 2 resting against the secondary insulating barrier 1, a primary thermally insulating barrier, hereafter referred to as primary insulating barrier 3, resting against the secondary sealed membrane 2, and a primary sealed membrane 4 intended to be in contact with the liquefied natural gas contained in the tank.The load-bearing structure can be formed by the hull or double hull of a ship. The load-bearing structure comprises a plurality of load-bearing walls defining the overall shape of the tank, usually a polyhedral shape, with each tank wall anchored to its respective load-bearing wall.

[0089] The secondary insulating barrier 1 comprises a plurality of secondary insulating panels 5 which are anchored to the load-bearing wall by means of secondary anchoring devices (not shown). The secondary insulating panels 5 are generally parallelepiped in shape and are arranged in parallel rows. Sealant beads (not shown) are interposed between the secondary insulating panels 5 and the load-bearing wall to compensate for deviations of the load-bearing wall from a flat reference surface. Kraft paper can be inserted between the sealant beads and the load-bearing wall to prevent the sealant beads from adhering to the load-bearing wall. Alternatively, the sealant beads are in direct contact with the load-bearing wall, thus ensuring that the secondary insulating panels 5 are fixed by adhesion to the load-bearing wall.

[0090] The structure of a secondary insulating panel 5, illustrated in Figure 2, comprises a base plate 7, a cover plate 8, and an insulating layer 9 sandwiched between the base plate 7 and the cover plate 8. The base plate 7 and the cover plate 8 are, for example, made of plywood. The insulating layer 9 is, for example, a layer of insulating polymer foam sandwiched between the base plate 7 and the cover plate 8. The insulating layer 9 is bonded to the base plate 7 and the cover plate 8. The insulating polymer foam may, in particular, be a polyurethane-based foam, optionally reinforced with fibers.

[0091] The secondary insulating panels 5 have recesses to receive the secondary anchoring devices. Such recesses are, for example, made in the insulating lining 9 and in the cover plate 8 so as to expose a corner portion of the base plate 7. The secondary anchoring devices have a base anchored to the load-bearing wall and a rod extending in the direction of the tank wall's thickness. The base is, for example, hollow and has an opening through which the rod passes; a nut is screwed onto the end of the rod housed in the hollow base to secure the rod to the base and thus to the load-bearing wall. In another embodiment, the secondary anchoring devices may be in the form of a rod welded to the inner shell.

[0092] In one embodiment, the recess is located in the corner areas. The corner portion of the base plate 7 has a cutout to allow the passage of the rod of the secondary anchoring device. A secondary support plate is engaged on the rod and held in place by a nut screwed onto an inner end of the rod opposite the base. This secondary support plate rests on the corner portions of the base plate 7 of adjacent secondary insulation panels 5, for example, four adjacent secondary insulation panels 5, in order to anchor said secondary insulation panels 5 to the load-bearing wall. In another variant, the secondary support plate rests on the secondary insulation panels 5 by means of a batten bearing against the corner portion of the base plate 7.

[0093] In another variant, the recess is placed on two lateral faces of the secondary insulating panels 5 and the secondary anchoring devices are placed in these recesses between two adjacent secondary insulating panels 5 along the width or length direction of said secondary insulating panels 5.

[0094] The cover plate 8 has on an internal face, i.e. on a face opposite the insulating lining 9, grooves for receiving welding supports 6.

[0095] The structure of the secondary insulating panels 5 and the secondary anchoring device are described above by way of example. Also, in another embodiment, the secondary insulating panels 5 may have a different general structure, for example that described in document WO2012 / 127141. The secondary insulating panels 7 are then made in the form of a box comprising a base plate, a cover plate and load-bearing walls extending, in the thickness direction of the tank wall, between the base plate and the cover plate and delimiting a plurality of compartments filled with an insulating material, such as perlite, glass wool or rock wool.

[0096] In another embodiment, the secondary insulating panels comprise a base plate, a cover plate, and an intermediate plate sandwiched between the base plate and the cover plate. The insulating lining then comprises a first layer sandwiched between the base plate and the intermediate plate, and a second layer sandwiched between the intermediate plate and the cover plate. The first layer of insulating lining is, for example, bonded to the base plate and the intermediate plate. The second layer of insulating lining is, for example, bonded to the intermediate plate and the cover plate. In this embodiment, the recess can be formed in the cover plate and the second layer of insulating lining only, with the secondary support plate resting on an exposed portion of the intermediate plate.Furthermore, the cutout allowing the passage of the rod is made in the intermediate plate, the first layer of insulating lining, and the base plate. Such a secondary insulating panel is described, for example, in document WO2014 / 096600.

[0097] In one embodiment, the secondary insulation panels are bonded to the load-bearing wall, for example using the aforementioned sealant beads. In this case, it is possible to eliminate the secondary anchoring devices and the recesses that receive them.

[0098] Returning to Figure 1, we observe that the secondary waterproof membrane 4 comprises a continuous layer of raised-edge metallic struts 10. The struts 10 are welded by their raised edges to parallel weld supports 6, which are fixed in grooves formed on the cover plates 8 of the secondary insulating panels 5. The struts 10 are, for example, made of Invar®: that is, an iron-nickel alloy whose coefficient of thermal expansion is typically between 1.2 x 10⁻¹² and 1.2 x 10⁻¹². -6 and 2.10 -6 K -1 It is also possible to use iron and manganese alloys whose coefficient of expansion is typically in the range of 7 to 9 x 10⁻¹¹. -6 K -1 .

[0099] The primary thermally insulating barrier 5 comprises a plurality of primary insulating panels 11 which are anchored to the load-bearing wall by means of primary anchoring devices 12, described in more detail below. The primary insulating panels 11 have a generally parallelepiped shape and are juxtaposed to form the primary insulating barrier 3. Furthermore, they may have dimensions of width, length, or thickness identical to or different from those of the secondary insulating panels 5. In particular, their thickness along the thickness direction of the tank wall is likely to be less than that of the secondary insulating panels 5. Each of the primary insulating panels 11 is offset from the secondary insulating panels 5 on which it rests.Thus, the adjacent corners of the primary insulating panels 11 are grouped together at the cover plate 8 of a secondary insulating panel 5 on which the said primary insulating panels 11 rest.

[0100] The primary insulating panels 11 may have a multilayer structure similar to that of the secondary insulating panels 5. Thus, in the example shown, the primary insulating panels 11 comprise, successively along the thickness direction of the tank wall, a base plate 13, for example made of plywood, a primary insulating lining 14, and a cover plate 15, for example made of plywood. The primary insulating lining is, for example, a layer of insulating polymer foam, for example, polyurethane-based foam, optionally reinforced with fibers. The insulating lining 14 is preferably bonded to the base plate 13 and the cover plate 15.

[0101] A primary insulating panel 11 has recesses at its corner areas so that the base plate 13 extends beyond the primary insulating lining 14 and the cover plate 15. Thus, the base plate 13 forms a bearing area at the corner areas of the primary insulating panel 11, intended to cooperate with a primary bearing plate 16 of the primary anchoring member 12. In the embodiment illustrated in Figure 3, a wedge 17 is added to the base plate 13, said wedge 17 having a shape similar to that of the bearing area and cooperating with the primary bearing plate 16 to anchor the primary insulating panel 11.

[0102] The base plate 13 of the primary insulation panel 11 has grooves 18 for receiving the raised edges of the strakes 10 of the secondary waterproofing membrane 2. The cover plate 15 has anchoring strips 19, shown in Figure 1, for anchoring the primary waterproofing membrane 4. These anchoring strips 19 are housed in counterbores formed on the inner face of the cover plate 15. The primary insulation panel 11 may also have relaxation slots 20 formed in the cover plate 15 and in an inner portion of the primary insulation lining 14. Such relaxation slots 20 serve to prevent deformation or degradation of the primary insulation panel 11 due to differential contractions between the cover plate 15 and the primary insulation lining 14.Such relaxation slots 20 also allow undulations 21 to work and thus avoid creating stresses in the primary waterproof membrane 4 and in the primary insulating barrier 4 in the case of a primary waterproof membrane 4 having undulations 21 as described below.

[0103] The structure of the primary insulating panel 11 is described above by way of example. Also, in another embodiment, the primary insulating panels 11 may have a different general structure, for example that described in document WO2012 / 127141.

[0104] In another embodiment, the primary insulating barrier 3 comprises primary insulating panels having at least two different types of structure, for example the two structures mentioned above, depending on their area of ​​implantation in the tank.

[0105] The primary waterproof membrane 4 comprises a continuous sheet of rectangular plates exhibiting two sets of mutually perpendicular corrugations 21. The rectangular plates are welded together, forming small overlapping areas along their edges, according to a known technique. A rectangular plate preferably has width and length dimensions that are integer multiples of the corrugation spacing and also integer multiples of the dimensions of the primary insulating panels 11.

[0106] A primary anchoring element 12 is described below with reference to Figures 3 to 5. Figure 3 shows a detailed view of the primary anchoring element 12 illustrated in Figure 2 under reference B. In Figures 4 and 5, the nut 32 and the support plate 16 are omitted. In Figures 3 to 5, only one primary anchoring element 12 is shown, and the description below for this anchoring element applies similarly to one, several, or all of the primary anchoring elements 12 integrated into the sealed and thermally insulated tank.

[0107] As explained above, in the embodiment illustrated in figures 1 to 5, the primary insulating panels 11 are anchored to the load-bearing wall via the secondary insulating panels 5. For this purpose, the cover plate 8 of the secondary insulating panel 5 has an anchoring plate 22. This anchoring plate 22 is housed in a recess 23 made in the cover plate 8.

[0108] The recess 23 has an internal section 24 with a first diameter and an external section 25 with a second diameter. The second diameter is larger than the first diameter, so that the external section 25 of the recess 23 forms lateral indentations interposed between a portion of the cover plate 8 surrounding the internal section 24 and the insulating gasket 9.

[0109] The anchor plate 22 has a shape complementary to the recess 23. An inner face 26 of the anchor plate 22 is flush with an inner face 27 of the cover plate 8 of the secondary insulating panel 5. Thus, the anchor plate 22 forms with the cover plate 8 a substantially continuous flat surface on which the secondary waterproofing membrane 2 rests. Furthermore, an outer section 28 of the anchor plate 22 is housed within the outer section 25 of the recess 23 and is thus interposed between the cover plate 8 and the insulating gasket 9. The anchor plate 22 is preferably bonded to the insulating gasket 9 of the secondary insulating panel. The anchor plate 22 is thus prevented from moving along the thickness direction of the tank wall. This anchor plate 22 also has a central threaded recess 29.

[0110] The primary anchoring member 12 comprises a base 30, a rod 31, the primary support plate 16 and a nut 32.

[0111] The base 30 has an external thread and is screwed into the central housing 29 of the anchor plate 22. In other words, the base 30 of the primary anchoring member 12 is anchored in the anchor plate 22.

[0112] The rod 31 extends from the base 30 along the thickness direction of the tank wall towards the interior of the tank. The rod 31 passes through an opening in the secondary waterproof membrane 2. As illustrated in Figures 1 to 3, this rod 31 extends into the space separating the corners of two primary insulating panels 11.

[0113] The primary support plate 16 has a central opening 60. This primary support plate 16 is engaged on the rod 31. The primary support plate 16 rests on the shims 17 arranged on the overhanging portions of the base plates 13 of the primary insulating panels 11 with which the primary anchoring member 12 cooperates. Furthermore, the inner end of the rod 31 opposite the base 30 is threaded, and the nut 32 is screwed onto this inner end of the rod 31 to support the primary support plate 16 on the shims 17. In the embodiment illustrated in Figure 3, spring washers 33, for example Belleville washers, are interposed between the primary support plate 16 and the nut 32.

[0114] In order to ensure the sealing of the secondary sealing membrane 2 at the orifice of said secondary sealing membrane 2 through which the rod 31 passes, the primary anchoring member 12 further includes a sealing washer 34.

[0115] This sealing washer 34 comprises an annular body 35 having a central orifice 36. The sealing washer 34 further comprises a flange 37 extending radially outwards from an external portion of the radially external face of the annular body 35. Moreover, an internal face 38 of the annular body 35 comprises a rib 39 projecting along the thickness direction of the tank wall. This rib 39 extends from a radially internal portion of said internal face 38. The flange 37 is, for example, formed by a peripheral portion of the annular body 35.

[0116] The sealing washer 34 is engaged on the rod 31, the rod 31 passing through the central orifice 36 of the sealing washer 34. The sealing washer 34 is interposed between the secondary sealing membrane 2 and the primary support plate 16. The central orifice 36 of the sealing washer 34 has a diameter larger than the diameter of the portion of the rod 31 passing through said central orifice 36. Thus, a transverse clearance, i.e., in a direction perpendicular to the thickness direction of the tank wall, separates a radially internal face delimiting the central orifice 36 of the annular body 35 and the rod 31. This clearance allows the sealing washer 34 to be movable transversely relative to the rod 31, and therefore relative to the primary support plate 16.

[0117] In an embodiment not shown, the central orifice is not circular and has a dimension in at least one transverse direction greater than the dimension of the rod 31 in said at least one transverse direction. In such an embodiment, a gap in said at least one transverse direction separates the central orifice 36 from the rod to allow movement of the sealing washer relative to the rod 31 in said at least one transverse direction.

[0118] The collar 37 is fixed in a watertight manner to the secondary waterproof membrane 2 around the opening of said secondary waterproof membrane 2. This watertight fixing is achieved for example by welding.

[0119] The primary anchoring member 12 has an anchoring shoulder 40 projecting radially outwards from the rod 31. This anchoring shoulder 40 is interposed between the sealing washer 34 and the primary support plate 16. The anchoring shoulder 40 has a flat anchoring surface 41 extending in a plane perpendicular to the thickness direction of the tank wall. This anchoring surface 41 faces inwards towards the tank.

[0120] The primary anchoring member 12 includes a deformable seal that provides a watertight connection between the rod 31 and the sealing washer 34. This deformable seal includes a bellows 42. An internal axial end of this bellows 42 is securely fixed to the rod 31. An external axial end of this bellows 42 is securely fixed to the sealing washer 34. More specifically, the internal axial end of the bellows 42 is securely anchored to the anchoring surface 41 of the anchoring shoulder 40. The external axial end of the bellows 42 is securely anchored to the rib 39 projecting from the inner face 38 of the annular body 35. The internal axial end of the bellows 42 is, for example, welded to the rod 31. The external axial end of the bellows 42 is, for example, welded to the sealing washer 34.

[0121] This bellows 42 has three deformable folds 61 in the embodiment illustrated in Figure 3. Not shown, the number of folds 61 in the bellows 42 is not limited to three and can be greater, taking into account the spacing between the shoulder 40 and the surface 38 of the collar 37. Thus, the bellows 42 can have between three and thirty-two folds 61, ideally from six to twenty-four folds 61, depending on this spacing, which is, for example, between 20 and 45 mm. The bellows 42 is substantially cylindrical. The folds 61 forming the bellows 42 have identical dimensions. Such a bellows 42 is, for example, made of stainless steel. In order to ensure the flexibility of said bellows 42, it has a low thickness, preferably less than 1 mm, for example between 0.1 and 0.5 mm and more particularly between 0.1 mm and 0.3 mm thick.

[0122] This bellows 42 creates a flexible, deformable, and watertight connection between the rod 31 and the sealing washer 34. This flexible and deformable connection, combined with the clearance between the sealing washer 34 and the rod 31, allows for relative movement in a watertight manner between the sealing washer 34 and the rod 31. Thus, with the sealing washer 34 fixed watertight to the secondary waterproofing membrane 2 and the rod 31 supporting the primary support plate 16 bearing on the primary insulation panels 11, relative movement is possible between the secondary waterproofing membrane 2 and the secondary insulation panels 5 and / or the primary insulation panels 11 without risk of damage to the secondary waterproofing membrane 2 or loss of the watertightness of the secondary waterproofing membrane 2.In particular, when the rod 31 is fixed on a secondary insulating panel, deformation and / or displacement of said secondary insulating panel 5 is possible without such deformation and / or displacement generating stress on the secondary waterproof membrane 2 or on the connection between the sealing washer 34 and the secondary waterproof membrane 2.

[0123] Such a relative displacement between the secondary insulating panels 5 and / or the primary insulating panels 11 and the secondary waterproof membrane 2 can occur due to differential contractions, deformation of the secondary insulating barrier 1 and / or the load-bearing wall, or due to stresses on the primary insulating panels 11 related to liquid movements in the tank.

[0124] In order to protect the bellows 42, for example during the construction of the tank and the assembly of the primary anchoring member 12, said primary anchoring member includes a bell 43. This bell 43 includes a mounting portion 44 and a protective portion 45. This bell 43 is combinable with the different types of bellows 42 described above and below.

[0125] The mounting portion 44 is flat and has a central opening. The bell 43 is mounted on the rod 31 of the primary anchoring member 12, said rod passing through the central opening of the mounting portion 44. The mounting portion is interposed between the anchoring shoulder 40 and the primary support plate 16. The bell is thus prevented from moving along the thickness direction of the tank wall by the primary support plate 16 on one side and by the anchoring surface 41 on the other.

[0126] The protective portion 45 is hollow and has an inner end joined to a peripheral edge of the mounting portion 44. The protective portion 45 extends from its inner end along the bellows 42 towards the sealing washer 34, the bellows 42 being housed within said hollow protective portion 45. The protective portion 45 is further flared so that an outer end of said protective portion 45 is aligned with the flange 37 of the sealing washer 34. Thus, the bell 43 completely surrounds the bellows 42, from the inner end of said bellows 42 on the anchoring surface 41 to the outer end of said bellows 42 fixed to the rib 39.

[0127] The outer end of the protective portion 45 has a lip 46 extending in a plane perpendicular to the thickness direction of the tank wall. This lip 46 forms a stop surface 47 located opposite the flange 37. Such a stop surface 47 prevents the flange 37, and therefore the sealing washer 34, from moving towards the interior of the tank, the bell 42 itself being blocked by the stop of its mounting portion 44 on the primary support plate 16.

[0128] Thus, with the collar 37 fixed in a hermetic manner to the secondary sealing membrane 2, when the load-bearing wall deforms or there is overpressure in the secondary sealing membrane 2, the local deformation of the secondary sealing membrane 2 at the level of the primary anchoring member 12 is blocked by the stop of the collar 37 of the sealing washer 34 on the stop surface 47. In another embodiment, the mounting portion 44 of the bell 43 is fixed to the rod, for example by welding.

[0129] In an embodiment not shown, the primary insulating panels 11 and the secondary insulating panels 5 have identical dimensions and are arranged so that the corners of the secondary insulating panels 5 are aligned along the thickness direction of the tank wall with the corners of the primary insulating panels 11. In such an embodiment, the primary anchoring member 12 is not anchored in a secondary insulating panel 5 but directly onto the secondary anchoring member. Such a configuration is described, for example, in document WO2014096600, which shows a joint anchoring device for the secondary insulating panels 5 and the primary insulating panels 11, the base 30 of the primary anchoring member 12 being fixed to one end of the secondary anchoring member.Thus, in this embodiment, a primary anchoring member as described above, the base 30 of the primary anchoring member 12 is not anchored in the anchoring plate 22 housed in a cover plate 8 of a secondary insulating panel 5 but in a base fixed to the inner end of the secondary anchoring member.

[0130] Figure 6 illustrates a primary anchoring element 12 according to a second embodiment. Elements identical to or fulfilling the same function as elements described above in Figures 1 to 5 bear the same reference numerals.

[0131] This second embodiment differs from the embodiment illustrated in figures 1 to 5 in that the annular body of the sealing washer has a radially external beveled face, i.e. inclined with respect to the thickness direction of the tank wall.

[0132] Figure 7 illustrates a primary anchoring element 12 according to a third embodiment. Elements identical to or fulfilling the same function as elements described above in Figures 1 to 5 bear the same reference numerals.

[0133] This third embodiment differs from the embodiment illustrated in Figures 1 to 5 in that the bellows 42 is flared. Thus, the folds 61 forming said bellows 42 have increasing dimensions from the inner axial end of the bellows 42 anchored on the anchoring surface 42 to the outer axial end of the bellows 42 anchored on the sealing washer 34.

[0134] Furthermore, in this third embodiment, the inner face 38 of the annular body 35 of the sealing washer 34 does not have the rib 39, said inner face 38 being flat. In this third embodiment, the outer axial end of the bellows 42 is directly fixed to the flat inner surface 38. In particular, since the bellows 42 has a flared shape, the outer axial end of said bellows 42 is fixed to a radially external peripheral edge of said inner surface 38.

[0135] This third embodiment also differs from the embodiment described opposite figures 1 to 5 in that the primary anchoring member 12 does not include a bell 43. Such a bell 43 could however be added.

[0136] In this third embodiment, the rod 31 has a laterally projecting shoulder 48. This shoulder 48 is interposed between the anchoring shoulder 40 and the sealing washer 34. Furthermore, this shoulder 48 has at least one transverse dimension greater than the dimension of the central orifice of the sealing washer 34. Thus, this shoulder 48 has an external face 49 opposite the internal surface 38 of the annular body 35 of the sealing washer 34. In other words, a peripheral portion of this external face 49 forms the stop surface 47. This shoulder 48 thus fulfills the function of a stop for the sealing washer 35, preventing the internal movement of said sealing washer 34 within the tank and preventing local deformation of the secondary sealing membrane 2.

[0137] Figure 8 illustrates a primary anchoring element 12 according to a fourth embodiment. Elements identical to or fulfilling the same function as elements described above in Figures 1 to 5 bear the same reference numerals.

[0138] In this fourth embodiment, the primary anchor plate 16 is replaced by an anchor cross 54. This anchor cross 54 has a mounting portion 55 and a plurality of support lugs 56, for example four support lugs 56 as illustrated in Figures 7 and 8 of document WO2014 / 057221.

[0139] The mounting portion 55 of the anchoring cross 54 is flat and extends in a plane perpendicular to the thickness direction of the tank wall. This mounting portion 55 has a central opening through which the rod 31 passes, so that the anchoring cross 54 is mounted on the rod 31.

[0140] Each support bracket 56 has an internal end joined to a peripheral edge of the mounting portion 55. Each support bracket 56 extends from the mounting portion 55 towards a bearing surface 57 formed by the overhanging portion of the base plate 13 of a primary insulation panel 11. An external end of the support bracket 56 has a lip 58 extending in a plane perpendicular to the thickness direction of the tank wall. This lip 58 bears against the bearing surface 57 so as to retain the primary insulation panel 11 on the secondary waterproof membrane 2.

[0141] Such an anchoring cross 54 provides some protection of the bellows 42 in a manner analogous to the protective bell 43 described above with regard to figures 1 to 5.

[0142] In this fourth embodiment, the inner end of the bellows 42 is anchored on a lateral face 59 of the anchoring shoulder 40, for example in a counterbore provided for this purpose in the external portion of said lateral face 58.

[0143] Figures 10 to 12 represent a primary anchoring element 12 according to a fifth embodiment. In these figures, elements identical to or fulfilling the same function as elements described above opposite Figures 1 to 5 bear the same reference numeral.

[0144] In this fifth embodiment, the protective portion 45 of the bell 43 is cylindrical and has a generatrix parallel to the thickness direction of the tank wall. The outer end of the protective portion 45 of the bell 43 is positioned flush with the inner face 38 of the annular body 35. In other words, the stop surface 47 formed by the rim 46 of the outer end of the protective portion 45 cooperates with the inner face 38 of the annular body 35 to prevent the sealing washer 34 from moving towards the inside of the tank. The collar 37 projects radially outwards from the annular body 35 beyond the rim 46. Furthermore, the internal axial end of the bellows 42 is anchored in a sealed manner, for example by welding, on an external face of the anchoring shoulder 40, that is to say on a face of the anchoring shoulder 40 turned towards the sealing washer 34.

[0145] When Liquefied Natural Gas (LNG) is stored in the tank, the movements of said LNG within the tank, for example related to the movements of a ship in which said tank is installed, can generate lateral stresses on the primary insulating panels 11. Typically, a movement of LNG in the tank can exert a lateral stress on the corrugations 21 of the primary sealing membrane 4. This lateral stress at said corrugation 21 is transmitted to the primary insulating panel 11 to which the primary sealing membrane 4 is anchored. Under the effect of this stress, the primary insulating panel 11 tends to move laterally, i.e. in a plane perpendicular to the thickness direction of the tank wall, and therefore to exert a stress on the primary anchoring member 12.

[0146] With the collar 37 projecting radially outwards from the annular body 35 beyond the rim 46 of the bell 43, the base plate 13 of the primary insulating panel 11 can be brought against the collar 37 during the movement of said primary insulating panel 11. Such a butt of the base plate 13 on the collar 37 generates a significant stress at the level of the watertight connection between the collar 37 and the secondary watertight membrane 2, this stress being able to jeopardize the integrity of the secondary watertight membrane 2.

[0147] To prevent the forces caused by lateral displacement of the primary insulation panel 11 from being absorbed by the sealing washer 34, this fifth embodiment includes a transfer wedge 62. The transfer wedge 62 allows the transverse force to be transferred to the rod 31 and its support, for example, the secondary insulation barrier. Furthermore, the transverse dimension of the wedge is smaller than the spacing between adjacent primary insulation panels to provide sufficient mounting tolerance and transmit the forces from one primary insulation panel to the rod 31.

[0148] This transfer wedge 62 here comprises a base 63, an envelope 64 and wings 65.

[0149] The base 63 has a flat shape extending perpendicularly to the thickness direction of the tank wall. This base 63 is circular in shape, with its center coaxial with the rod 31. The base 63 has a central orifice 66. This central orifice 66 is circular and coaxial with the rod 31. The dimensions of the central orifice 66 are larger than the dimensions of the flange 37, such that a gap separates the base 63 from the flange 37.

[0150] The base 63 rests on the secondary sealing membrane 2 around the collar 37. The base plates 13 of the primary insulating panels 11 cooperating with the primary anchoring element 12 may have an external counterbore 67 to accommodate the base 63.

[0151] The envelope 64 comprises an outer skirt 68 and an inner skirt 69 connected by a central plate 82.

[0152] The outer skirt 68 has a circular cylindrical wall whose generatrix is ​​parallel to the thickness direction of the tank wall. This outer skirt 68 extends from the inner periphery of the base 63, that is, from the edge of the central orifice 66 of the base 63. The outer skirt 68 extends inwards towards the tank over a thickness, along the thickness direction of the tank wall, greater than or equal to the thickness, taken along said thickness direction of the tank wall, of the annular body 35. Thus, an inner end of the outer skirt 68 is radially aligned with the protective portion 45 of the bell 43.

[0153] The central plate 82 extends in a plane perpendicular to the thickness direction of the tank wall. This central plate 82 extends radially inward from the inner end of the outer skirt 68. The central plate 82 has a central opening 83 whose inner diameter is slightly larger than the outer diameter of the protective portion 45 of the bell. Thus, the central plate 82 surrounds the protective portion 45 of the bell 43.

[0154] The inner skirt 69 has a circular cylindrical wall whose generatrix is ​​parallel to the thickness direction of the tank wall. This inner skirt 69 extends from the inner periphery of the central plate 82, that is, from the edge of the central plate 82 that defines the central orifice 83. The inner skirt 69 extends inwards towards the tank over a thickness less than the thickness of the protective portion 45 of the bell 43. Thus, the inner skirt 69 surrounds the protective portion 45 of the bell 43 over only a portion of the thickness of said protective portion 45.

[0155] Typically, the casing 64 surrounds the collar 37 and forms a housing, visible in figures 11 and 12, in which the collar 37 is housed with a clearance, ensuring the protection of said collar 37.

[0156] Thus, when a primary insulating panel 11 is subjected to a stress causing lateral displacement of said primary insulating panel 11, the base plate 13 of said primary insulating panel 11 abuts against the transfer wedge 62, typically against the base 63 and / or against the outer skirt 68. Since the transfer wedge 62 surrounds the bell 43 and the distance separating the transfer wedge 62 from the bell 43 is less than the distance separating the transfer wedge 62 from the collar 37, the transfer wedge 62 abuts against the bell 43 without generating significant stress on the collar 37. In other words, the path of the forces related to this lateral displacement of the primary insulating panel 11 passes through the base plate 13 of the primary insulating panel 11, which exerts a force on the transfer wedge 62. This transfer wedge then exerts a force on the bell 43 and the rod 31.Thus, the transfer wedge 62 ensures that the path of forces related to a lateral displacement of a primary insulating panel 11 does not pass through the collar 37, thus limiting the stresses at the level of the watertight connection between the collar 37 and the secondary watertight membrane 2.

[0157] In the embodiment illustrated in Figures 10 to 12, the transfer wedge 62 further comprises four wings 65 facilitating the positioning of the transfer wedge 62 relative to the adjacent primary insulating panels 11. These positioning wings 65 are regularly distributed circumferentially around the casing 64. These wings 65 extend radially from the casing 64 parallel to the thickness direction of the tank wall. Each of said wings 65 is housed between two primary insulating panels 11 cooperating with the primary anchoring member 12. These wings 65 separate compartments providing independent support for each of the primary insulating panels 11.

[0158] In an embodiment not shown, the outer skirt 68 extends towards the inside of the tank beyond the bottom plate 13 of the primary insulating panels 11. Thus, during a lateral movement of a primary insulating panel 11, the insulating lining 14 is also brought against the outer skirt 68 in order to transfer the forces related to the lateral movement of the primary insulating panel 11 to the transfer wedge 62.

[0159] Figures 13 and 14 illustrate a primary anchoring organ 12 according to a sixth embodiment.

[0160] This sixth embodiment differs from the fifth embodiment illustrated opposite Figures 10 to 12 in that the outer end of the protective portion 45 of the bell 43 is arranged opposite the collar 37. In addition, the rim 46 of the outer end of the protective portion 45 projects radially beyond the collar 37. Thus, the stop surface 47 formed by the rim 46 of the outer end of the protective portion 45 cooperates with the inner face of the collar 37 to block the movement of the sealing washer 34 towards the interior of the tank.

[0161] In this embodiment, the transfer wedge 62 is formed by a block 84. This block 84 has a central orifice. This central orifice has an internal diameter slightly larger than the external diameter of the protective portion 45 of the bell 43, so that the block 84 surrounds the protective portion 45 of the bell 43.

[0162] The block 84 has a thickness, taken along the thickness direction of the tank wall, less than the thickness of the bottom plate 13 of the adjacent primary insulating panels 11, so that an internal face of the block 84 is arranged outside, along the thickness direction of the tank wall, of the internal face of the bottom plates 13. Furthermore, in the embodiment illustrated in Figure 13, the block 84 rests on an internal face of the rim 46 of the protective portion 45 of the bell 43.

[0163] A peripheral lateral face of block 84 is generally complementary in shape to the recesses formed in the base plates 13 of the primary insulating panels 11 that cooperate with the primary anchoring element 12. In other words, the distance between the base plates 13 of the primary insulating panels 11 and block 84 corresponds approximately to a mounting clearance. Thus, a lateral displacement of a primary insulating panel 11 generates, almost from the outset of said displacement, a bearing on the peripheral lateral face of block 84.

[0164] Thus, during a lateral movement of a primary insulating panel 11, the base plate 13 of said primary insulating panel 11 abuts against the transfer wedge 62, and more particularly against the peripheral lateral face of the block 84, and the transfer wedge abuts against the bell 43 and the rod 31 without exerting substantial stress on the collar 37. The stress exerted by the primary insulating panel 11 on the transfer wedge 62 is therefore transmitted to the rod 31 without substantially passing through the connection between the collar 37 and the secondary sealing membrane 2.

[0165] An example of a method for mounting a primary anchoring element is described below with reference to figures 15 to 17. In these figures 15 to 17 and in the description below, elements identical or fulfilling the same function as elements already described above bear the same reference.

[0166] Similar to the description above with reference to Figures 1 to 5, the anchor plate 22 is housed in a recess 23 made in the cover plate 8 of a secondary insulating panel 5. The inner face 26 of the anchor plate 22 is flush with an inner face 27 of the cover plate 8 of the secondary insulating panel 5. The anchor plate 22 further has a central threaded recess 29 for receiving the base 30 of the primary anchoring member 12.

[0167] Preferably, the primary anchoring member 12 is at least partially prefabricated. A prefabricated portion of the primary anchoring member 12 comprises, for example, as illustrated in Figure 16, the base 30, the rod 31, the bellows 42 whose internal axial end is fixed on the anchoring shoulder 40, and the sealing washer 34 on which the external axial end of the bellows is fixed.

[0168] However, with a primary anchoring element 12 thus prefabricated, the sealing washer 34 is rotationally fixed to the rod 31 via the bellows 42. Therefore, when the rod 31 is rotated to screw the base 30 into the threaded central housing 29, the sealing washer 34 is also rotated. This rotation of the sealing washer 34 can generate friction between the outer face of said sealing washer 34 and the secondary sealing membrane 3, particularly at the end of the screwing of the base 30 into the housing 29. Such friction generates torsion in the bellows 42, which is likely to damage said bellows 42 and thus compromise its sealing.

[0169] To prevent twisting in the bellows 42 when screwing the base 30 into the housing 29, the body 35 of the sealing washer 34 has flats 85 on its lateral face connecting the collar 37 and the inner face 38 of the body 35. Similarly, the anchoring shoulder 40 also has flats 86. The flats 85 of the sealing washer 34 and the flats 86 of the anchoring shoulder 40 preferably extend in the same planes.

[0170] The assembly method for the primary anchoring element 12 involves the use of a hollow key 87 having internal faces 88 that are complementary to the flats 85 and 86. Furthermore, the hollow portion of the key 87 preferably has a height greater than the height of the rod 31 and at least greater than, or equal to, the distance between the internal axial end of the rod and the flat 85 carried by the sealing washer 34. Thus, due to the complementarity between the internal faces 88 of the key and the flats 85 and 86, a rotation of the key 87 results in a rotation of both the rod 31, and therefore of the base 30, and of the sealing washer 34.In Figure 16, the anchoring shoulder 40 and the body 35 have six flats 85 and 86, however the number and dimensions of these flats may be different the primary anchoring member 12 may have one, two or more flats 85 and 86 complementary to the internal faces 88 of the key 87 so that the sealing washer 34 and the anchoring shoulder, and therefore the stem 31 and the base 30, are linked in rotation when using the key 87.

[0171] To mount the prefabricated portion of the primary anchoring member 12 onto the anchoring plate 22, said prefabricated portion is inserted into the hollow portion of the key 87. The key 87 is then turned to screw the base 30 into the housing 29. As the sealing washer 34 is turned with the rod 31, the friction between the sealing washer 34 and the secondary sealing membrane 3 does not cause the bellows 42 to twist.

[0172] When the base 30 is fully screwed into the housing 29, the bell 43 can be attached to the rod 31 as illustrated in Figure 17. Alternatively, the prefabricated portion of the anchoring member can also include the bell 43 which is then fixed, for example by welding, to the rod 31.

[0173] In this alternative illustrated in Figure 17, the bell 43 has a flat 89 similar to the flat 86 of the anchoring shoulder 40. Furthermore, the sealing washer 34, and more particularly the flat 85, is arranged radially beyond the rim 46 of the bell 43. Thus, the internal faces 88 of the key 87 cooperate with the flat of the bell 43 and the flat of the sealing washer 34 to allow the base 30 to be screwed into the housing 29 while rotating the sealing washer 34 so as not to generate torsion in the bellows 42.

[0174] The technique described above for making a sealed and thermally insulating tank can be used in different types of tanks, for example to make an LNG tank in an onshore installation or in a floating structure such as a methane tanker or other.

[0175] With reference to Figure 9, a cutaway view of a LNG carrier 70 shows a sealed and insulated tank 71 of generally prismatic shape mounted in the double hull 72 of the vessel. The wall of the tank 71 comprises a primary watertight barrier intended to be in contact with the LNG contained in the tank, a secondary watertight barrier arranged between the primary watertight barrier and the double hull 72 of the vessel, and two insulating barriers arranged respectively between the primary watertight barrier and the secondary watertight barrier and between the secondary watertight barrier and the double hull 72.

[0176] As is known per se, loading / unloading pipelines 73 arranged on the upper deck of the ship can be connected, by means of suitable connectors, to a marine or port terminal to transfer a cargo of LNG to or from the tank 71.

[0177] Figure 9 shows an example of a marine terminal comprising a loading and unloading berth 75, a subsea pipeline 76, and an onshore facility 77. The loading and unloading berth 75 is a fixed offshore facility comprising a movable arm 74 and a tower 78 that supports the movable arm 74. The movable arm 74 carries a bundle of insulated flexible pipes 79 that can be connected to the loading / unloading pipelines 73. The steerable movable arm 74 accommodates all LNG carrier sizes. An unshown connecting pipeline extends inside tower 78. The loading and unloading station 75 allows the loading and unloading of the LNG carrier 70 from or to the onshore facility 77. This facility includes liquefied gas storage tanks 80 and connecting pipelines 81 linked by the subsea pipeline 76 to the loading or unloading station 75.The subsea pipeline 76 allows the transfer of liquefied gas between the loading or unloading station 75 and the onshore facility 77 over a long distance, for example 5 km, which allows the LNG carrier 70 to be kept a long distance from the coast during loading and unloading operations.

[0178] To generate the pressure necessary for the transfer of the liquefied gas, pumps on board the ship 70 and / or pumps equipping the land installation 77 and / or pumps equipping the loading and unloading station 75 are used.

[0179] Although the invention has been described in connection with several particular embodiments, it is clearly evident that it is by no means limited to them and that it includes all technical equivalents of the means described as well as their combinations if these fall within the scope of the invention.

[0180] The use of the verb "comporter", "comprendre" or "include" and its conjugated forms does not exclude the presence of other elements or steps than those stated in a claim.

[0181] In claims, any reference sign in parentheses shall not be interpreted as a limitation of the claim.

Claims

A watertight and thermally insulating tank comprising a tank wall, the tank wall comprising, successively from the outside of the tank to the inside of the tank along a thickness direction of the tank wall, a secondary insulating barrier (1) intended to be anchored to a load-bearing wall, a secondary watertight membrane (2) resting on the secondary insulating barrier (1), a primary insulating barrier (3) resting on the secondary watertight membrane (2) and a primary watertight membrane (4) resting on the primary insulating barrier (3) and intended to be in contact with a product contained inside the tank, the primary insulating barrier (3) comprising a plurality of juxtaposed primary insulating panels (11), the tank further comprising a plurality of primary anchoring devices (12) intended to be retained, directly or indirectly, on the load-bearing wall,each of said primary anchoring devices (12) cooperating with at least one primary insulating panel (11) of the plurality of primary insulating panels (11) so as to retain said at least one primary insulating panel (11) on the secondary waterproof membrane (2), in which a said primary anchoring device (12) comprises: - a base (30) intended to be retained, directly or indirectly, on the load-bearing wall, - a rod (31) extending along the thickness direction of the tank wall from said base (30) towards the primary waterproof membrane (4), said rod (31) passing through an orifice of the secondary waterproof membrane (2), - a support element (16, 54) mounted on the rod (31), said support element (16, 54) bearing on a primary insulating panel (11) so as to retain said primary insulating panel (11) on the secondary waterproof membrane (2),- a sealing washer (34) engaged on the rod (31) between the support element (16) and the orifice of the secondary waterproofing membrane (2), the sealing washer (34) having a central orifice (36) through which the rod (31) passes, the sealing washer (34) being fixed in a watertight manner to the secondary waterproofing membrane (2) around the orifice of said secondary waterproofing membrane (2), - a deformable seal (42) connecting said sealing washer (34) and the rod (31) in a watertight manner so as to allow relative movement between the sealing washer (34) and the rod (31). A sealed and thermally insulating tank according to claim 1, wherein the central orifice (36) of the sealing washer (34) has a transverse dimension greater than the transverse dimension of a portion of a rod (31) engaged in said central orifice (36), so as to allow the movement of the rod (31) in said central orifice (36) of the sealing washer (34) in a direction perpendicular to the thickness direction of the tank wall. A watertight and thermally insulating tank according to claim 1 or 2, wherein the primary anchoring member (12) further comprises a stop carried by the rod (31), said stop being arranged on the rod (31) between the support element (16) and the sealing washer (34), the stop having a stop surface (47) opposite the sealing washer (34) in order to stop a movement towards the primary watertight membrane (4) along the thickness direction of the tank wall of said sealing washer (34) relative to the rod (31). A sealed and thermally insulating tank according to claim 3, in which the rod (31) has a shoulder (48), said shoulder (48) projecting laterally from the rod (31) beyond the central orifice (36) of the sealing washer (34) so ​​that an external face (49) of said shoulder (48) forms the abutment surface (47). A watertight and thermally insulating tank according to any one of claims 1 to 4, wherein the primary anchoring member (12) further comprises a bell (43) mounted on the rod (31), said bell (43) comprising a mounting portion (44) and a protective portion (45), the mounting portion (44) having a central passage through which the rod (31) passes, the protective portion (45) extending along the thickness direction of the tank wall from the mounting portion (44) towards the sealing washer (34), the protective portion (45) being hollow, the deformable seal (42) being housed in the protective portion (45). A sealed and thermally insulating tank according to claim 3 in combination with claim 5, wherein an external end of the protective portion (45) opposite the mounting portion (44) forms the stop surface (37) opposite the sealing washer (34). A sealed and thermally insulating tank according to claim 5 or 6, in which the bell (43) is fixed on the rod (31). A sealed and thermally insulating tank according to any one of claims 5 to 7, further comprising a transfer wedge arranged around the bell in a gap between the bell and the adjacent primary insulating panels. A sealed and thermally insulating tank according to any one of claims 5 to 8, wherein the sealing washer (34) has a flat (85) and the bell (43) has a flat (89), said flats being configured to be engaged by a screwing tool enabling the rod (31) and the sealing washer (34) to be rotationally locked together without twisting the deformable seal (42). A sealed and thermally insulating tank according to any one of claims 1 to 9, in which the deformable seal comprises a deformable bellows (42), said deformable bellows (42) being hollow and extending around and axially along the rod (31), a first axial end of said bellows (42) being fixed in a sealed manner on the rod (31) and a second axial end of said bellows (42) being fixed in a sealed manner on the sealing washer (34). A sealed and thermally insulating tank according to claim 10, in which the bellows (42) has at least three folds. A sealed and thermally insulating tank according to claim 10 or 11, in which the bellows (42) is flared in shape, the second axial end of the bellows (42) fixed on the sealing washer (34) having a circumferential dimension greater than the circumferential dimension of the first axial end of the bellows (42) fixed on the rod (31). A sealed and thermally insulating tank according to any one of claims 1 to 12, in which the base (30) of the primary anchoring member (12) is rigidly anchored in the secondary insulating barrier (1). A sealed and thermally insulating tank according to any one of claims 1 to 13, wherein an internal end of the rod (31) opposite the base (30) is threaded, and wherein the primary anchoring member (12) further comprises a nut (32) screwed onto said internal threaded end, the support element (16, 54) being interposed between said nut (32) and the base (30) of the primary anchoring member (12), the deformable seal being interposed between the support element (16, 54) and the sealing washer (34). A sealed and thermally insulating tank according to claim 14, in which an elastic washer (33) is interposed between the nut (32) and the support element (16, 54). A sealed and thermally insulating tank according to any one of claims 1 to 15, wherein the primary anchoring member (12) has an anchoring shoulder (40) projecting laterally from the rod (31), said anchoring shoulder (40) forming an anchoring surface (41) developing in a plane perpendicular to the thickness direction, said anchoring surface (41) being turned towards the support element (16, 54), the deformable seal being fixed in a sealed manner on said anchoring surface (41). Vessel (70) for the transport of a cold liquid product, the vessel comprising a double hull (72) and a tank according to any one of claims 1 to 16 disposed in the double hull. Transfer system for a cold liquid product, the system comprising a vessel (70) according to claim 17, insulated pipes (73, 79, 76, 81) arranged to connect the tank installed in the hull of the vessel to a floating or land-based storage facility (77) and a pump to drive a flow of cold liquid product through the insulated pipes from or to the floating or land-based storage facility to or from the vessel tank. Method of loading or unloading a ship (70) according to claim 17, wherein a cold liquid product is conveyed through insulated pipes (73, 79, 76, 81) from or to a floating or land-based storage facility (77) to or from the ship's tank (71).