ES2983426T3 - Vessel that includes a tank - Google Patents

Abstract

[The invention relates to a vessel comprising a metallic inner hull (1) comprising an inner surface and an outer surface, an outer hull arranged on the outside of the inner hull, and at least one tank arranged in the inner hull and resting against the inner surface of the inner hull, the tank comprising at least one tank wall, the inner hull comprising a plurality of hull sheets (16) welded together, the vessel comprising at least one through-element (20) passing through an opening (3) made in the inner hull and in the tank wall, at least one hull sheet bordering said opening; the vessel comprising at least one metal plate (30) comprising at least one hole (31) through which the through-element passes in the inner hull, the metal plate having a thickness greater than the thickness of said at least one hull sheet bordering the opening, the metal plate being welded to said at least one hull sheet bordering the opening and around the entire perimeter of the opening. (Automatic translation with Google Translate, without legal value)

Description

DESCRIPTION

Vessel that includes a tank

Technical area

The present invention relates to the field of vessels comprising tanks, and in particular watertight and thermally insulated tanks, with membranes. In particular, the invention relates to the field of vessels comprising watertight and thermally insulated tanks for storing and/or transporting liquefied gas at low temperature, such as tanks for transporting Liquefied Petroleum Gas (also known as LPG) with, for example, a temperature between -50°C and 0°C, or for transporting Liquefied Natural Gas (LNG) at about -162°C at atmospheric pressure. These tanks can be installed on land or on a floating structure. The tank can be used to transport liquefied gas or to receive liquefied gas used as fuel for the propulsion of the vessel.

Technological background

In the prior art, vessels are known as double-hulled vessels, i.e. consisting of an inner hull and an outer hull. These vessels may contain one or more tanks containing fuel, either for transport or for use as propulsion fuel. These tanks are arranged in the inner hull and fixed to it. These tanks may be, for example, watertight and thermally insulated membrane tanks for storing a liquefied gas. In this case, the walls of said tank comprise a multi-layer structure superimposed in a thickness direction and comprising at least one sealing membrane and at least one thermally insulating barrier located between the inner lining and the sealing membrane.

In order for these tanks to function properly, the through-elements pass through a plurality of holes made in the inner shell and in the walls of the tank. These through-elements may be, for example, loading/unloading pipes or a drainage well structure.

The inner hull has a network of reinforcements on its outer surface to give rigidity to the structure, in particular to withstand the pressure of the fluid contained in the tank or tanks. This network of reinforcements is interrupted around openings made in the inner hull, for example by interrupting or deviating the reinforcements of said network around the opening.

However, it has been observed that the beam of a ship including such tanks deflects in the longitudinal direction of the ship due to a variety of factors. For example, deflection of the ship's beam is caused by the hull changing from its dry-docked state to its floating state, or by variations in the temperature of the hull between the manufacturing temperature and the operating temperature, or by forces exerted on the ship by waves.

By way of example, such vessels are described in particular in patent applications US 2017/219166 A1, FR 3 035 175 A1, WO 2016/166481 A2 and FR 3083843 A1.

Summary

The invention is based on the hypothesis that during these bending phenomena, the inner shell is subjected to high mechanical stresses which are concentrated at the level of the holes made in it. These concentrated stresses can cause a deformation of the said opening, called "ovalization" in the case of a circular opening, which can damage the inner shell and the tank.

The idea behind the invention is to limit the risk of deformation caused by a hole made in the inner hull, which could damage it.

In one embodiment, the invention provides a vessel having a metallic inner hull comprising an inner surface and an outer surface, an outer hull disposed externally of the inner hull opposite the outer surface, and at least one tank disposed in the inner hull and abutting the inner surface of the inner hull, the tank comprising at least one tank wall, the inner hull comprising a plurality of hull sheets welded together,

The vessel comprises at least one through-member passing through an opening in the inner hull and in the tank wall, and at least one hull plate bordering said opening;

wherein the vessel includes at least one metal plate comprising at least one opening through which the through-element passes, the metal plate has a thickness greater than the thickness of the at least one hull skin bordering the opening, the metal plate is welded to the at least one hull skin bordering the opening, the metal plate extends around the opening (3).

Thanks to these characteristics, the ship's metal plate, due to its greater thickness than the inner hull, makes it possible to stiffen the structure around the hole to limit its deformation when the ship's beam bends.

According to embodiments, said vessel may comprise one or more of the following features.

The thickness of the metal plate and hull sheets is measured in a direction orthogonal to the outer surface of the inner hull.

In one embodiment, the vessel comprises a plurality of through-elements passing through said opening in the inner hull and in said tank wall, the metal plate comprising a hole for each through-element. In one embodiment, the vessel comprises a plurality of through-elements passing through a plurality of openings in the inner hull and in said tank wall, and the vessel has a plurality of metal plates each comprising at least one opening through which one of the through-elements passes, the metal plates being separated by at least one hull plate.

According to one embodiment, the thickness of the metal plate is greater than or equal to 1.2 times the thickness of the at least one lining plate bordering the opening.

In this way, the metal plate is thick enough to spread the stresses and stiffen the structure around the hole, without making the welding operation between the two elements too complex and limiting the deformations associated with welding.

In one embodiment, the metal plate is made of stainless steel and the cladding sheets are made of carbon steel.

According to one embodiment, the hole is circular and the through element has a circular cross section.

In one embodiment, the vessel comprises a first network of reinforcements welded to an outer surface of the metal plate, and a second network of reinforcements welded to the outer surface of the inner hull; and wherein the first network of reinforcements comprises inner reinforcements and outer reinforcements, the outer reinforcements being arranged to form a reinforcement frame around the inner reinforcements, the reinforcements of the second network of reinforcements being welded to the outer reinforcements.

In the same way as the thickness of the metal plate, the first reinforcement network makes it possible to stiffen the structure around the hole in order to limit any deformation of the hole due, for example, to the bending of the ship's beam. In addition, the first reinforcement network guarantees mechanical continuity with the second reinforcement network.

In one embodiment, each external reinforcement is in the form of a plate.

In one embodiment, the reinforcements of the first reinforcement network are made of stainless steel, and the reinforcements of the second reinforcement network are made of carbon steel.

In one embodiment, the internal reinforcements are evenly distributed around the through element.

The term "evenly spaced" is used here to mean spaced apart at a constant pitch, in this case a constant angular pitch.

In one embodiment, the internal reinforcements are irregularly distributed around the through element.

The term "irregularly distributed" is used here to mean spacing at a variable pitch, in this case a variable angular pitch.

In one embodiment, the second network of reinforcements comprises primary reinforcements and secondary reinforcements, each primary reinforcement being formed essentially in a plane orthogonal to the outer surface of the inner liner and being welded on the one hand to the inner liner and on the other hand to the outer liner, and each secondary reinforcement being arranged essentially in a plane orthogonal to the outer surface of the inner liner and being welded to the inner liner and formed at a distance from the outer liner.

In one embodiment, the tank wall is a tank roof wall and the through member is a tube. In one embodiment, the internal stiffeners are welded to the metal plate and to the external stiffeners.

In one embodiment, the internal stiffeners are bracket-shaped and increase in thickness from the tube to the external stiffeners.

The thickness of the reinforcements is measured in a direction orthogonal to the outer surface of the inner hull.

In one embodiment, the thickness of the internal reinforcements increases linearly, quadratically, or exponentially until reaching a thickness equal to the distance between the metal plate and the outer cover.

The thickness of the internal reinforcements is measured in the same way as for the metal plate, that is, in a direction orthogonal to the outer surface of the inner hull.

According to one embodiment, the first network of reinforcements comprises at least three internal reinforcements, preferably eight internal reinforcements, preferably evenly distributed around the hole.

According to one embodiment, each internal reinforcement is fixed to a portion of an external reinforcement, a reinforcement of the second series of reinforcements being fixed to said portion of an external reinforcement.

In one embodiment, the roof wall comprises a thermal insulation barrier supported by the inner lining, and a sealing membrane supported by the thermal insulation barrier, the thermal insulation barrier and the sealing membrane being interrupted at a distance from the tube, the sealing membrane being fixed to the metal plate by a connecting ring around the tube, the connecting ring comprising a portion protruding from the outer surface of the metal plate to form a circular reinforcement.

In one embodiment, at least one end of the internal reinforcements is welded to the circular reinforcement.

According to one embodiment, the external reinforcements are formed in a plane orthogonal to the external surface of the inner hull, the external reinforcements being welded on one side to the metal plate and on the other side to the outer hull.

In one embodiment, the internal reinforcements have a lower surface in contact with the metal plate, said surface extends from the circular reinforcement to the outer frame.

In one embodiment, the inner reinforcements have a lateral surface in contact with one of the outer reinforcements, said surface extending from the metal plate to the outer hull.

According to one embodiment, the tank wall is a bottom wall of the tank and the through element is a drain well structure or a support foot for a loading/unloading mast.

According to one embodiment, the reinforcement frame is an outer reinforcement frame, the inner reinforcements comprise a first group of reinforcements, and a second group of reinforcements, the first group of reinforcements forming an inner reinforcement frame around the hole and within the outer reinforcement frame, the inner reinforcement frame is welded to the outer reinforcement frame; the second group of reinforcements comprises at least two connecting reinforcements; the connecting reinforcements are welded, on the one hand, to the structure of the drainage well and, on the other, to the inner reinforcement frame.

In one embodiment, the reinforcing frame is an outer reinforcing frame, the inner reinforcements comprise a first stiffening group, a second reinforcing group and a third stiffening group, the first reinforcing group forming a first reinforcing frame around the hole and within the outer reinforcing frame, the first reinforcing frame being welded to the outer reinforcing frame, the second group of reinforcements forming a second reinforcing frame around the hole and within the first reinforcing frame, the second reinforcing frame being welded to the first reinforcing frame; the third group of reinforcements comprises at least two connecting reinforcements, the connecting reinforcements being welded, on the one hand, to the structure of the drainage well and, on the other hand, to the second reinforcing frame.

In one embodiment, the joint reinforcements are evenly distributed around the drain well structure.

In one embodiment, the third group of reinforcements comprises four tie reinforcements.

In one embodiment, the drain well structure comprises a drain well bottom and the vessel comprises two drain well stiffeners, the drain well stiffeners being welded to an external surface of the drain well bottom.

In one embodiment, the drain well ribs intersect at the center of the drain well base and are oriented at 90° to each other.

In one embodiment, each drainage well reinforcement is oriented at 45° to one of the attachment reinforcements.

According to one embodiment, the tank is a sealed and thermally insulated membrane tank for storing a liquefied gas.

According to one embodiment, the tank wall comprises a multi-layer structure formed in a thickness direction from the outside to the inside of the tank of a secondary thermal insulation barrier supported by the inner liner, a secondary sealing membrane supported by the secondary thermal insulation barrier, a primary thermal insulation barrier supported by the secondary sealing membrane, and a primary sealing membrane supported by the primary thermal insulation barrier and adapted to be in contact with the liquefied gas.

In 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 inner hull of the vessel to a floating or onshore storage facility and a pump to drive a flow of cold liquid product through the insulated pipes from or to the floating or onshore storage facility to or from the tank of the vessel.

According to one embodiment, the invention also provides a method of loading or unloading such a vessel, wherein a cold liquid product is transported through insulated pipelines from or to a floating or onshore storage facility to or from the vessel's tank.

Brief description of the figures

The invention will become better understood, and other objects, details, features and advantages thereof will become clearer in the course of the following description of various particular embodiments of the invention, given by way of illustration only and not of limitation, with reference to the accompanying drawings.

Figure 1 shows a cross-sectional side view of a double-hull vessel comprising a plurality of tanks.

Figure 2 is a perspective view of detail II of Figure 1, with two tubes passing through the inner hull of the vessel.

Figure 3 is a schematic top view of detail II of Figure 1, with a tube passing through the inner hull of the vessel.

Figure 4 is a schematic cross-sectional view of detail IV of Figure 1, with a drain well structure running through the inner hull.

Figure 5 is a schematic bottom view of Detail IV of Figure 1.

Figure 6 is a schematic representation of a LNG tanker comprising a plurality of tanks and a terminal for loading/unloading said tanks.

Description of the achievements

The following description describes a vessel 70 comprising an inner hull 1, an outer hull 2 and a plurality of storage tanks 71.

Figure 1 shows, in particular, an LNG carrier 70 for storing and transporting liquefied gas. However, the invention is not limited to this type of vessel and relates to any 70 mm double-hull vessel 1, 2 equipped with at least one tank containing a fuel, either for transport or for use as fuel.

Thus, the vessel 70 shown in Figure 1 comprises four tanks arranged in the inner hull 1 and fixed thereto. The inner hull 1 is formed by a plurality of hull plates 16 assembled together. In order for these tanks to function correctly, openings 3 are provided through the inner hull 1 to allow the passage of equipment through the tank. Within these openings 3 of the inner hull 1, passage elements are arranged, such as a drain well structure 9 shown in Figures 4 and 5 or a pipe 20 shown in Figures 2 and 3.

Referring to Figure 2, it can be seen that the vessel 70 comprises a metal plate 30 for making the connection between the through element 9, 20 and the inner hull 1 at the opening 3. Thus, the metal plate 30 is welded to the hull plates around the opening 3 and has a hole 31 through which the through element 9, 20 passes. The through element 9, 20 is fixed to the metal plate 30 around the hole 31. The metal plate 30 is flat and is arranged substantially in the plane of the inner hull plates 1 bordering the opening 3.

As indicated above, it is advantageous in the area of the holes 31 to stiffen the structure formed by the inner shell 1 and the metal plate 30 to limit any deformation of the hole 31.

To achieve this, the thickness of the metal plate 30 has been increased compared to the thickness of the hull sheets 16 of the inner hull 1 bordering the opening 3. For example, the thickness of the metal plate 30 is 1.5 times greater than the thickness of the skin sheets 16 bordering the opening 3. To further improve the rigidity of the metal plate 30 without significantly increasing its thickness, a first reinforcing network 32 is welded to the metal plate 30. The first reinforcing network 32 will be described in more detail below, in several different ways depending on the type of through-element.

The inner hull 1 has a second network of reinforcements 17 on its outer surface, as can be seen in particular in figure 2. The second network of reinforcements reinforces the inner shell 1 so that it can withstand the pressure of the fluid contained in the tank. The second network of reinforcements 17 comprises primary reinforcements 18 and secondary reinforcements 19 alternating with each other. The primary and secondary reinforcements 18 and 19 extend in a first series in the longitudinal direction of the vessel and also in a second series in the transverse direction of the vessel for the upper and lower walls of the inner hull 1.

In another embodiment, the primary reinforcements 18 extend in the longitudinal direction and the secondary reinforcements 19 extend in the transverse direction.

Each primary reinforcement 18 is formed in a plane orthogonal to the outer surface of the inner hull 1 and is welded, on the one hand, to the inner hull 1 and, on the other hand, to the outer hull 2 to form the joint between the hulls 1, 2. Each secondary reinforcement 19 is also located in a plane orthogonal to the outer surface of the inner hull 1, but these are smaller than the primary reinforcements 18 and are therefore welded only to the inner hull 1 and therefore at a distance from the outer hull 2. The primary reinforcements 18 are plate-shaped and are advantageously provided with holes to allow free circulation of operators or of air present in the space between the inner hull 1 and the outer hull 2.

Figures 2 and 3 represent embodiments in which the passing element is a tube 20 that passes through the upper wall of the inner hull 1 and the upper wall of the tank 71, Figure 2 being a particular case in which two tubes 20 pass through the inner hull 1 very close to each other.

In the embodiments of Figures 2 and 3, the roof wall 4 comprises a multi-layer structure not shown and comprising at least one thermally insulating barrier supported by the inner surface of the inner hull 1, and at least one sealing membrane supported by the thermally insulating barrier. The thermally insulating barrier and the sealing membrane are interrupted at a distance from the tube 20. The sealing membrane is fixed to the metal plate 30 by means of a connection ring (not shown) around the entire tube 20. The connection ring has a part protruding from the outer surface of the metal plate 30 to form a circular reinforcement 21 around the tube 20 at a distance therefrom. The circular reinforcement 21 reinforces the fixing area of the sealing membrane to prevent the metal plate 30 from bending in this area due to the stresses exerted by the sealing membrane.

Figures 2 and 3 show the arrangement of the first reinforcement network 32 formed on the outer surface of the metal plate 30 in the case of a tube 20. The first reinforcement network 32 comprises inner reinforcements 34 and outer reinforcements 33. The outer reinforcements 33 are made in the form of a plate and arranged to form a reinforcement frame around the inner reinforcements 34. The outer reinforcements 33 are arranged in a plane orthogonal to the outer surface of the upper wall of the inner hull 1. The outer reinforcements 33 are welded to the metal plate 30 and to the outer hull 2. Furthermore, reinforcements of the second reinforcement network 17 are welded to the outer reinforcements 33. In the embodiments shown, the primary reinforcements 18 of the second reinforcement network 17 are fixed as an extension of the outer reinforcements 33.

As shown in Figures 2 and 3, there are eight internal reinforcements 34 evenly distributed around the tube 20. In this example, the internal reinforcements 34 are oriented radially with respect to the axis of the tube 20 and distributed at 45° intervals, taking the axis of the tube 20 as a reference, as shown in Figure 3. However, the number of internal reinforcements 34 may vary depending on the diameter of the tube 20, so that their number may be smaller or larger, as long as they are evenly distributed around the tube 20.

The internal reinforcements 34 are in the form of a square and are welded to one of the external reinforcements 33, to the metal plate 30 and to the circular reinforcement 21. The internal reinforcements 34 have a lower surface in contact with the metal plate 30 and welded to it. This upper surface extends from the circular reinforcement 21 to the external reinforcement 33. Furthermore, the internal reinforcements 34 have a lateral surface in contact with the external reinforcement 33 and welded to it. This lateral surface extends from the metal plate 30 to the outer shell 2. In this configuration, two internal reinforcements 34 are welded to each external reinforcement 33. Therefore, each internal reinforcement 34 is fixed to a portion of an external reinforcement 33 and a reinforcement of the second series of reinforcements 17 is fixed to this portion of the external reinforcement 33 so as to be located in the extension of the internal reinforcement 34, as shown in figure 3.

This arrangement of the circular reinforcement 21, the internal reinforcements 34, the external reinforcements 33 and the second reinforcement network 17 guarantees continuity in the mechanical absorption of the forces and a uniform distribution of these forces in order to limit the deformation of the opening 31 of the metal plate 30.

The internal reinforcements 34 increase in thickness from the circular reinforcement 21 to the external reinforcement 33 in order to absorb as best as possible the forces exerted around the hole 31 of the metal plate 30 and to transfer them uniformly from the circular reinforcement 21 to the external reinforcements 33. In the embodiment shown, this growth is exponential, starting from a value less than the height of the circular reinforcement 21 and reaching a thickness equal to the distance between the metal plate 30 and the outer shell 2.

In the particular case of Figure 2, where two tubes 20 pass through the inner lining 1 close to each other, the first reinforcing network 32 of the first tube 20 and the first reinforcing network 32 of the second tube 20 share the same external reinforcement 33. In Figure 2, two tubes 20 pass through the same opening 3, so that only one metal plate 30 is needed. Consequently, this metal plate 30 is provided with two holes 31 and two first reinforcing networks 32 are fixed to it. As shown in Figure 2, the metal plate 30 can be rectangular in shape, this shape varying depending on the number of passing elements 9, 20. For example, in the case of three passing elements 9, 20 passing through the same metal plate 30, the latter can be L-shaped.

In the case, not shown, where the two or more through elements 9, 20 are distant from each other and it is necessary to have a plurality of openings 3 in the inner shell 1 and in the tank wall 4, a metal plate 30 is provided for each of the openings 3. Each of these metal plates 30 is also provided with the necessary number of holes 31 depending on the number of through elements 9, 20 passing through said opening 3.

Figures 4 and 5 show an embodiment in which the through element is a drain well structure 9 passing through the bottom wall of the tank and the bottom wall of the inner hull 1.

Figure 4 schematically shows the multilayer structure of the bottom wall 4 of the tank in the case where the tank is a sealed and thermally insulating membrane tank for storing liquefied gas. In this design, the walls 4 of the tank are formed by a multilayer structure fixed to the load-bearing walls of the inner hull 1 and comprising two watertight membranes 5, 7 alternating with two thermally insulating barriers 6, 8. By way of example, such membrane tanks are described in particular in patent applications WO14057221, FR2691520 and FR2877638 relating respectively to the Mark V©, Mark III © and NO96 © products developed by the applicant.

The tank wall 4 is mounted on the inner hull 1 of a double-hull vessel 70. The tank wall 4 has a multi-layer structure successively including a secondary thermal insulation barrier 8 fixed to the inner hull 1, a secondary sealing membrane 7 supported by the secondary thermal insulation barrier 8, a primary thermal insulation barrier 6 covering the secondary sealing membrane 7, and a primary sealing membrane 5 supported by the primary thermal insulation barrier 6.

The structure of the drain well 9 comprises a first container 10 in communication with the interior of the tank, and a second container 11 containing the first container 10. The first container 10 is continuously connected to the primary sealing membrane 5, thereby completing it in a hermetic manner. Similarly, the second container 11 is continuously connected to the secondary sealing membrane 7, which completes it in a hermetic manner. The connection between the first container 10 and the primary sealing membrane 5 is made by means of a first collar 13, while the connection between the second container and the secondary sealing membrane 7 is made by means of a second collar 14.

The structure of the drain well 9 is also provided with a rigid container 12 which is fixed around the metal plate 30 in the hole 31. The first and second containers 10, 11 are located inside the rigid container 12. The rigid container 12, the first container 10 and the second container 11 are, for example, coaxial cylindrical containers, as shown in Figure 4. The second container 11 is fixed to the metal plate 30 by fixing fins 15. Advantageously, the fixing fins 15 may have a translational degree of freedom corresponding to a radial direction of the second container 11 to allow the latter to thermally contract and expand.

In the embodiment of Figures 4 and 5, and in the same manner as in the embodiments of Figures 2 and 3, the first reinforcement network 32 comprises inner reinforcements 35, 36, 37 and outer reinforcements 33. The outer reinforcements 33 are plate-shaped and are arranged to form an outer reinforcement frame around the inner reinforcements 35, 36, 37. The outer reinforcements 33 are arranged in a plane orthogonal to the outer surface of the upper wall of the inner hull 1. The outer reinforcements 33 are welded to the metal plate 30 and to the outer hull 2. Furthermore, the reinforcements of the second reinforcement network 17 are welded to the outer reinforcements 33. In the embodiments shown, the primary reinforcements 18 of the second reinforcement network 17 are fixed as an extension of the outer reinforcements 33. Therefore, the outer reinforcements 33 are arranged in the same manner as in Figures 4 and 5. In the embodiments shown, the first reinforcement network 32 comprises inner reinforcements 35, 36, 37 and outer reinforcements 33. 2 and 3. However, the arrangement of the primary reinforcements 35, 36, 37 for the embodiment shown in Figures 4 and 5 is different.

As illustrated in Figure 5, the internal reinforcements 35, 36, 37 comprise a first group of reinforcements 35, a second group of reinforcements 36 and a third group of reinforcements 37. The first reinforcement group 35 forms a first reinforcement frame 35 around the hole 31 and within the outer reinforcement frame 33. The first reinforcement frame 35 is welded to the outer reinforcement frame 33, extending the reinforcements 35 to fit over the outer reinforcements 33. The second reinforcement group 36 also forms a second reinforcement frame 36 around the hole 31 and within the first reinforcement frame 35. In the same way as the first frame 35, the second reinforcement frame 36 is welded to the first reinforcement frame 35, extending the reinforcements 36.

Finally, the third group of reinforcements 37 comprises two connecting reinforcements 37. The connecting reinforcements 37 are welded to the rigid container 12 of the drainage well structure 9 and to the second reinforcing frame 36. The connecting reinforcements 37 are located on both sides of the rigid container 12. In the same way as in the case of the internal reinforcements 34 of Figure 2, the connecting reinforcements 37 can advantageously have an increasing thickness from the rigid container 12 towards the second reinforcing frame 36, in order to absorb as best as possible the forces exerted around the hole 31 of the metal plate 30 and to transfer them uniformly from the rigid container 12 to the external reinforcements 33 through the different groups of internal reinforcements 35, 36, 37.

The drain well structure 9 comprises a drain well base 38 to which two drain well stiffeners 39 are welded. The drain well stiffeners 39 are welded to an outer surface of the drain well base 38. The drain well stiffeners 39 are arranged in a plane orthogonal to the outer surface of the drain well base 38. In the embodiment shown in Figure 5, the drain well stiffeners 39 intersect at the center of the drain well base 38 and are oriented at 90° to each other. In addition, each drain well stiffener 39 is oriented at 45° to the joining stiffeners 37.

Referring to Figure 6, a sectional view of an LNG carrier 70 shows a generally prismatic shaped sealed and insulated tank 71 mounted in the double hull 72 of the tanker. The double hull 72 consists of an inner hull 1 and an outer hull 2. 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 disposed between the primary watertight barrier and the double hull 72 of the vessel, and two insulating barriers disposed respectively between the primary watertight barrier and the secondary watertight barrier and between the secondary watertight barrier and the double hull 72.

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

Figure 6 shows an example of an offshore terminal comprising a loading and unloading station 75, a subsea pipe 76 and an onshore facility 77. The loading and unloading station 75 is a fixed offshore facility consisting of a movable arm 74 and a tower 78 supporting the movable arm 74. The movable arm 74 carries a bundle of insulated flexible hoses 79 which can be connected to the loading/unloading pipes 73. The rotating arm 74 can be adapted to all sizes of LNG tankers. A connecting pipe (not shown) extends inside the tower 78. The loading and unloading station 75 enables the LNG carrier 70 to be loaded and unloaded from or to the onshore facility 77. It comprises liquefied gas storage tanks 80 and connecting pipes 81 linked by the subsea pipe 76 to the loading or unloading station 75. The subsea pipe 76 enables liquefied gas to be transferred between the loading or unloading station 75 and the onshore facility 77 over long distances, for example 5 km, meaning that the LNG carrier 70 can be kept long distance from shore during loading and unloading operations.

To generate the pressure necessary to transfer the liquefied gas, pumps on board the vessel 70 and/or pumps installed at the shore-based facility 77 and/or pumps installed at the loading and unloading station 75 are used.

Although the invention has been described in relation to several particular embodiments, it is evident that it is in no way limited thereto and that it includes all the means described, as well as combinations thereof, if they fall within the scope of the invention as described in the claims.

The use of the verb "contain", "comprising" or "including" and their conjugated forms does not exclude the presence of elements or stages other than those established in a claim.

In the claims, any reference signs in parentheses should not be construed as a limitation of the claim.

Claims (20)

1. Vessel (70) with a metal inner hull (1) comprising an inner surface and an outer surface, an outer hull (2) arranged outside the inner hull (1) facing the outer surface, and at least one tank (71) arranged in the inner hull (1) and resting against the inner surface of the inner hull (1), the tank comprising at least one tank wall (4), the inner hull (1) comprising a plurality of metal hull plates (16) welded together, the vessel (70) comprising at least one through element (9, 20) passing through an opening (3) made in the inner hull (1) and in the wall (4) of the tank, at least one metal hull plate (16) bordering said opening (3); wherein the vessel (70) comprises at least one metal plate (30) comprising at least one opening (31) through which the through element (9, 20) passes, the metal plate (30) having a thickness greater than the thickness of said at least one metal hull plate (16) bordering the opening (3), the metal plate (30) being welded to the at least one metal hull plate (16) bordering the opening (3), the metal plate (30) extending around the opening (3). 2. Vessel (70) according to claim 1, wherein the thickness of the metal plate (30) is greater than or equal to 1.2 times the thickness of the at least one metal hull plate (16) bordering the opening (3). 3. Vessel (70) according to claim 1 or claim 2, wherein the metal plate (30) is made of stainless steel and the metal plates of the hull (16) are made of carbon steel. 4. Vessel (70) according to one of claims 1 to 3, wherein the hole (31) is circular and the through element (9, 20) has a circular cross section. 5. Vessel (70) according to one of claims 1 to 4, wherein the vessel (70) comprises a first network of reinforcements (32) welded to an outer surface of the metal plate (30), and a second network of reinforcements (17) welded to the outer surface of the inner hull (1); and wherein the first reinforcing network (32) comprises inner stiffeners (34, 35, 36, 37) and outer stiffeners (33), the outer stiffeners (33) being arranged to form a reinforcing frame around the inner stiffeners (34, 35, 36, 37), the stiffeners of the second reinforcing network (17) being welded to the outer stiffeners (33). 6. Vessel (70) according to claim 5, wherein the reinforcements of the first reinforcement network (32) are made of stainless steel, and the reinforcements of the second reinforcement network (17) are made of carbon steel. 7. Vessel (70) according to claim 5 or claim 6, wherein the internal reinforcements (34, 35, 36, 37) are uniformly distributed around the through element (9, 20). 8. Vessel according to claim 5 or claim 6, wherein the internal reinforcements (34, 35, 36, 37) are irregularly distributed around the through element (9, 20). 9. Vessel (70) according to one of claims 5 to 8, wherein the second network of reinforcements (17) comprises primary reinforcements (18) and secondary reinforcements (19), each primary reinforcement (18) being formed essentially in a plane orthogonal to the outer surface of the inner hull (1) and welded on the one hand to the inner hull (1) and on the other hand to the outer hull (2), and each secondary reinforcement (19) being formed essentially in a plane orthogonal to the outer surface of the inner hull (1) and welded to the inner hull (1) and arranged at a distance from the outer hull (2). 10. Vessel (70) according to one of claims 5 to 9, wherein the internal reinforcements (34) are welded on the one hand to the metal plate (30) and on the other hand to the external reinforcements (33). 11. Vessel (70) according to one of claims 5 to 10, wherein the internal reinforcements (34) are square-shaped and have a thickness that increases from the through element (20) towards the external reinforcements (33). 12. Vessel (70) according to one of claims 5 to 11, wherein the first network of reinforcements (32) comprises at least three internal reinforcements (34) distributed uniformly around the hole (31). 13. Vessel (70) according to one of claims 5 to 12, wherein each internal reinforcement (34) is fixed to a portion of an external reinforcement (33), a reinforcement of the second reinforcement network (17) being fixed to said portion of external reinforcement (33). 14. Vessel (70) according to one of claims 1 to 13, wherein the tank wall (4) is a tank roof wall and the through element is a tube (20). 15. A vessel (70) according to claim 14, wherein the roof wall (4) comprises a heat-insulating barrier (8) supported by the inner hull (1), and a sealing membrane (7) supported by the heat-insulating barrier (8), the heat-insulating barrier (8) and the sealing membrane (7) being interrupted at a distance from the tube (20), the sealing membrane being fixed to the metal plate (30) by means of a connecting ring around the tube (20); the connecting ring comprising a part protruding from the outer surface of the metal plate (30) to form a circular reinforcement (21). 16. Vessel (70) according to claim 15 taken in combination with one of claims 5 to 13, wherein at least one end of the internal reinforcements (34) is welded to the circular reinforcement (21). 17. Vessel (70) according to one of claims 1 to 13, wherein the tank wall (4) is a tank bottom wall and the through-element is a drain well structure (9). 18. Vessel (70) according to one of claims 1 to 17, wherein the tank (71) is a sealed and thermally insulated membrane tank intended for the storage of a liquefied gas. 19. A system for transferring a cold liquid product, the system comprising a vessel (70) according to one of claims 1 to 18, insulated pipes (73, 79, 76, 81) arranged so as to connect the tank (71) installed in the inner hull (1) of the vessel (70) to a floating or land-based storage facility (77) and a pump for driving 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 (70). 20. Method for loading or unloading a ship (70) according to one of claims 1 to 18, wherein a cold liquid product is transported via 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).