Double access hatch for liquefied gas transport tank

Abstract

The invention relates to a wall (1) of a tank for storing and / or transporting liquefied gas, comprising a duct (2) passing through said wall (1) in a thickness direction (E) of said wall (1) and a closure device (3) configured to close said duct (2), said closure device (3) comprising at least one hatch (4) configured to provide access to the interior of the tank.

Description

Technical Field

[0001] The present invention relates to storage tanks, particularly to the field of tanks for storing liquefied gas. More particularly, the present invention relates to an apparatus for accessing the interior of such a tank, for example, for inspection and / or maintenance work.

Background Art

[0002] Liquefied gas carrier ships generally have a double-wall structure that defines a tank intended to receive liquefied gas. It should be understood that "liquefied gas" means any substance that is in the gaseous state under standard pressure and temperature conditions and becomes liquid by cooling. The tank generally has an upper wall interrupted at several locations by openings. These openings can be, for example, protruding structures in the form of turrets or chimneys, and can correspond to structures referred to as gas domes, liquid domes or manholes. The first turret functions as an inlet to various devices for handling the cargo, namely, a filling line, an emergency pump line, a discharge line connected to a discharge pump, a spray line, and a supply line connected to a spray pump. The second turret functions as an inlet to a vapor recovery pipe.

[0003] Thus, the tank may be provided with a submersible pump for discharging liquefied gas. The upper wall is provided with an opening for the maintenance and / or inspection of the submersible pump. Separate from those dedicated to the discharge pump, another opening is provided for the purpose of tank maintenance. Thus, the latter opening is dimensioned to allow the passage of replacement parts of the tank structure.

[0004] A first drawback of these openings at several locations on the upper wall of the tank is the increased risk of leakage at a plurality of weld points crossing the membrane.

[0005] A second disadvantage of the plurality of openings is that the heat escape path formed reduces the heat insulation of the tank. As a result, the evaporation rate of the liquefied gas contained in the tank increases, ultimately leading to a decrease in the transportation capacity of the ship equipped with such a tank.

[0006] A third disadvantage of these plurality of openings is that, particularly with regard to various insulation layers, the arrangement of metal parts constituting the film, and the mechanical constraints caused by these openings, the presence of the openings complicates the design and manufacture of such tanks. SUMMARY OF THE INVENTION

[0007] The object of the present invention is to overcome at least one of the above-mentioned disadvantages and provide further advantages by proposing a new type of wall for a liquefied gas transportation and / or storage tank.

[0008] Another objective of the present invention is to rationalize the number of openings made in the wall of a liquefied gas transportation and / or storage tank.

[0009] According to one embodiment, the present invention provides a wall of a tank for storing and / or transporting liquefied gas. The wall includes a duct passing through the wall in the thickness direction of the wall, and a closing device for closing the duct. The closing device includes at least one hatch configured to provide access to the interior of the tank.

[0010] Therefore, according to the present invention, it becomes possible to combine two openings in the upper wall of the tank, both of which open into the same internal volume of the tank. Further, instead of having interruptions in the seal film and the heat insulation barrier at two separate positions in the upper wall, the interruptions are only in one place. Therefore, the sealing property of the wall and the heat insulation property of the same wall are improved.

[0011] According to one embodiment, the closing device is an assembly including a plurality of elements such as a hatch, a cover, a second duct, a first plug, and / or a second plug. Such elements will be described in detail below.

[0012] According to one embodiment, when viewed in a plane orthogonal to the wall thickness direction, the duct has a rectangular cross-section.

[0013] According to one embodiment, the rectangular cross-section is a square.

[0014] According to one embodiment, the length of one side of the square is 1.3 m to 1.7 m, preferably 1.4 m to 1.5 m.

[0015] According to one embodiment, when viewed in a plane orthogonal to the wall thickness direction, the duct has a circular cross-section.

[0016] According to one embodiment, the circular cross-section has a diameter of 1.3 m to 1.7 m, preferably 1.4 m to 1.5 m.

[0017] According to one embodiment, the duct includes a first opening configured to open to the environment outside the tank and a second opening configured to open to the inside of the tank, and the closing device includes a cover for closing the first opening.

[0018] According to one embodiment, the cover and the hatch extend in different planes.

[0019] According to one embodiment, the extending surface of the cover is substantially parallel to the extending surface of the hatch.

[0020] According to one embodiment, the extending surface of the closing device and the extending surface of the cover are substantially orthogonal to the wall thickness direction.

[0021] According to one embodiment, the cover has a through passage that provides access to the interior of the tank, and the hatch is configured to close the through passage. Thus, the hatch can be mechanically connected to and / or placed on the cover.

[0022] According to one embodiment, the duct is a first duct, the closing device includes a first plug and a second plug, at least a part of the first plug extends through the layer of the wall and is adjacent to the inner surface of the first duct, at least a part of the second plug extends through the layer of the wall inside the first duct, and the first plug and the second plug are separated by a second duct. Here and hereinafter, it should be understood that a plug is a movable part that at least partially closes a duct by inserting at least a part of it into the duct.

[0023] According to one embodiment, at least a part of the second plug has a shape complementary to the inner surface of the second duct.

[0024] According to one embodiment, the second plug and the hatch are fixed to each other. Here, it will be understood that the second plug and the hatch are connected to each other such that pulling out or tilting the hatch is transmitted to the second plug along this movement.

[0025] According to other embodiments, the second plug includes a heat insulating material.

[0026] According to one embodiment, the second plug includes a housing. The housing is defined by the hatch and a panel connected to the hatch by at least one rod. The second plug includes a heat insulating material disposed within the housing. The heat insulating material is disposed, for example, between the hatch and the panel in the thickness direction of the wall.

[0027] According to another embodiment, the second plug includes a heat insulating material and a panel. The heat insulating material is connected to the lower surface of the hatch, and the panel is fixed to the heat insulating material.

[0028] According to one embodiment, the heat insulating material extends within the second duct, and the length of the heat insulating material measured along the thickness direction of the wall is at most the same as the length of the second duct measured along the thickness direction of the wall.

[0029] According to one embodiment, the heat insulating material extends over the entire length of the second duct measured along the thickness direction.

[0030] Therefore, the second plug has at least the same heat insulation performance as the wall of the tank in the region without an opening.

[0031] According to one embodiment, the heat insulating material is composed of a polyurethane foam. According to one embodiment, the polyurethane foam is reinforced with glass fibers.

[0032] According to other embodiments, the heat insulating material is composed of a polyethylene foam or a polypropylene foam.

[0033] According to other embodiments, the heat insulating material is composed of mineral wool. According to one embodiment, the mineral wool is selected from glass wool, rock wool, and mixtures thereof.

[0034] According to one embodiment, the panel is in the same plane as the free end of the second duct extending inside the tank.

[0035] According to one embodiment, when viewed in a plane orthogonal to the thickness direction of the wall, the panel has a circular cross-section.

[0036] According to one embodiment, the panel is a plywood panel, a composite panel, or a metal panel.

[0037] According to one embodiment, at least a part of the first plug has a shape complementary to the inner surface of the first duct. Thus, the first plug can fill the space defined by the inner surface of the first duct.

[0038] According to one embodiment, the first plug and the cover are fixed to each other. Thereby, the first plug can be pulled out simultaneously with the removal of the cover.

[0039] According to one embodiment, the first plug includes at least one heat-insulating self-supporting panel disposed around the second duct. Here, it will be understood that the heat-insulating self-supporting panel extends to surround the second duct from the inner surface of the first duct, that is, to the outer surface of the second duct.

[0040] According to one embodiment, the first plug includes an adhesive configured to cause a mechanical connection between the heat-insulating self-supporting panel and the cover. In other words, the heat-insulating self-supporting panel is fixed to the cover by the adhesive. According to one embodiment, the adhesive is a mastic. Advantageously, the flatness defect of the hull can be compensated for by the mastic. For this reason, the first plug and the heat-insulating panel can be arranged at the same level along the vertical axis Z.

[0041] According to one embodiment, the heat-insulating self-supporting panel includes a heat-insulating block made of rigid polyurethane, and a plywood panel on which the rigid polyurethane block is placed. According to other embodiments, instead of the plywood panel, a composite panel or a metal panel made of, for example, aluminum or stainless steel can be used.

[0042] According to other embodiments, the heat-insulating self-supporting panel is a box formed by a plywood panel and filled with a mineral wool such as glass wool or rock wool.

[0043] According to one embodiment, the heat-insulating self-supporting panel is in contact with the inner surface of the first duct. Thus, there is no space between the inner surface of the first duct and the heat-insulating self-supporting panel.

[0044] According to one embodiment, the heat-insulating self-supporting panel contacts the second duct. Therefore, there is no space between the second duct and the heat-insulating self-supporting panel.

[0045] According to one embodiment, the first plug is composed of mineral wool such as glass wool or rock wool. The mineral wool can fill the space that may exist between the self-supporting panels and / or the space between the panel surrounding the self-supporting panel or the second duct and the second duct itself.

[0046] According to one embodiment, the heat-insulating self-supporting panel is in the same plane as the free end of the second duct extending inside the tank.

[0047] According to one embodiment, when viewed in a plane orthogonal to the thickness direction of the wall, the cross-sectional area of the second duct is smaller than the cross-sectional area of the first duct.

[0048] According to the present invention, when viewed in a plane orthogonal to the thickness direction of the wall, the cross-section of the second duct is inscribed in the cross-section of the first duct.

[0049] According to one embodiment, when viewed in a plane orthogonal to the thickness direction of the wall, the second duct has a circular cross-section.

[0050] According to one embodiment, the circular cross-section of the second duct has a diameter of 0.8 m to 1.2 m, more specifically 0.9 m to 1.1 m.

[0051] According to other embodiments, when viewed in a plane orthogonal to the thickness direction of the wall, the second duct has a triangular cross-section or a quadrangular cross-section such as a square or a rectangle.

[0052] According to one embodiment, the second duct comprises a flange configured to cooperate with a hatch to close the second duct. In other words, the hatch abuts against the flange so as to cover the second duct. In other words, the hatch is placed on the cover so as to completely close the opening on the outer surface side of the second duct.

[0053] According to one embodiment, the second duct has a free end inside the tank, and the free end extends in an extending plane parallel to the extending plane of the wall, and the extending planes are separate from each other.

[0054] According to one embodiment, the flange surrounds the second duct at the first opening. In other words, the flange extends circumferentially across the contour of the first opening.

[0055] According to one embodiment, the cover and the second duct are securely connected to each other. The cover and the second duct are held together, for example, by welding to each other and / or by tightening using a plurality of bolts. The welding can be performed, for example, on the outer surface of the second duct on the side opposite to the inner surface of the second duct. In this context, it will be understood that the second duct passes through the cover via the through passage of the cover.

[0056] According to one embodiment, in the thickness direction of the wall, the upper part of the second duct projects from the cover toward the outside of the tank.

[0057] According to one embodiment, the closing device comprises a reinforcing part that is circumferentially arranged with respect to the second duct and extends from the cover toward the outside of the tank in the thickness direction of the wall.

[0058] According to one embodiment, the wall includes, in the direction of its thickness, at least one thermal barrier and at least one sealing film intended to contact the liquefied gas present in the tank, and the sealing film at least partially faces the first duct in the thickness direction of the wall. In other words, even at the initial manufacture of the tank and after the operation that requires cutting the sealing film, a part of the sealing film closes the first duct.

[0059] Therefore, the thickness direction of the wall can be defined as the direction perpendicular to the deployment surface of the sealing film.

[0060] According to one embodiment, the sealing film has a notch for allowing a part of the second duct to pass through.

[0061] According to one embodiment, the thermal barrier is a primary thermal barrier, and the sealing film is a primary sealing film intended to contact the petroleum gas inside the tank. The wall includes a secondary thermal barrier and a secondary sealing film. The secondary sealing film is disposed in contact with the secondary insulation barrier, the primary thermal barrier is disposed in contact with the secondary sealing film, and the primary sealing film is disposed in contact with the primary thermal barrier.

[0062] According to one embodiment, the primary sealing film includes corrugated portions.

[0063] According to one embodiment, the present invention proposes a tank for storing and / or transporting liquefied gas, including at least one wall according to the present invention.

[0064] According to one embodiment, the liquefied gas is an ultra-low temperature fluid. The liquefied gas is selected from liquefied natural gas, liquefied petroleum gas, liquid ethane, liquid propane, liquid argon, liquid ammonia, and liquid hydrogen.

[0065] Regarding the closing device, its closed state has been described. When it is in the open state, the second plug, and / or the first plug, and / or the hatch are outside the tank with the hatch tilted on the pivot axis, or they are completely separated from the closing device and thus from the wall forming the subject matter of the present invention. The same applies when the cover is separated from the tank wall.

[0066] According to one embodiment, the present invention also provides a method for providing access to the interior of a tank according to the present invention. For example, to allow equipment to pass through or for human maintenance work, the method includes removing the second plug to access the interior of the tank, i.e., the step of entering the interior of the tank from the outside of the tank, cutting a part of the sealing film around the closing device, and removing the closing device. Thus, it is possible to introduce larger equipment into the interior of the tank from the outside than in the first step. For example, it is possible to introduce the corner panels of the primary or secondary layer of the tank.

[0067] Due to the dimensions of the hatch, it can also be referred to as a manhole. Due to the dimensions of the first duct, it can also be referred to as an equipment hole.

[0068] According to one embodiment, the present invention finally provides a method for closing the first duct obtained from a method for providing access to the interior of a tank according to the present invention. The method includes the steps of repositioning the closing device in the first duct, welding the closing panel to the sealing film, and repositioning the hatch.

[0069] Other features and advantages of the present invention will become more apparent on the one hand from the following description and on the other hand from a plurality of exemplary embodiments shown non - limitatively with reference to the accompanying schematic drawings.

Brief Description of the Drawings

[0070]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0071] First, the present invention will be described in detail with reference to the drawings for the implementation of the present invention. However, it should be noted that these drawings can, of course, help to better define the present invention as needed. Also, note that throughout the drawings, elements performing similar and / or identical functions are given the same reference numerals.

[0072] In the following description, the direction of the longitudinal axis X, the direction of the lateral axis Y, and the direction of the vertical axis Z are represented by the trihedron (X, Y, Z) in the drawings. The horizontal plane is defined as a plane perpendicular to the vertical axis and having the direction of the longitudinal axis X and the direction of the lateral axis Y. The longitudinal plane is defined as a plane perpendicular to the lateral axis and having the direction of the longitudinal axis X and the direction of the vertical axis X. The lateral plane is defined as a plane perpendicular to the longitudinal axis and having the direction of the lateral axis Y and the direction of the vertical axis X.

[0073] The direction of the longitudinal axis X is parallel to the longitudinal direction of the ship equipped with the tank according to the present invention.

[0074] The support structure formed on the inner wall of the double hull of a liquefied gas carrier ship will be described below with reference to the drawings. Such a support structure can particularly have a polyhedral shape, for example, a prism shape. Such a support structure includes a longitudinal wall having a lower wall, side walls, and an upper wall. The longitudinal wall extends parallel to the longitudinal direction of the ship.

[0075] The longitudinal wall is interrupted in the longitudinal direction of the ship by a transverse wall perpendicular to the longitudinal direction of the ship. The longitudinal wall and the transverse wall meet at an edge.

[0076] Each wall of the support structure supports the respective tank wall. In FIGS. 1 to 3, the wall 1 of the tank supported by the upper wall of the support structure is shown. As shown in these drawings, the wall 1 includes at least one heat insulation barrier 7. A sealing film 8 intended to contact a fluid such as liquefied petroleum gas stored in the tank is attached to the heat insulation barrier 7.

[0077] The heat insulation barrier 7 is composed of an insulating material having the shape of juxtaposed panels made of a heat insulating material. These panels are composed of a foamed or cellular synthetic resin, or other natural or synthetic heat insulating materials. Further, the heat insulation barrier 7 can be composed of a filler, such as mineral wool like glass wool or rock wool. This filler is intended to be inserted between the juxtaposed panels. These panels can further be composed of plywood panels. The resin is adhered to the first side surface, and the sealing film 8 is screwed and / or welded to the second side surface opposite to the first side surface. In one embodiment not shown, these panels are composed of composite panels or metal panels made of, for example, aluminum or stainless steel instead of plywood panels.

[0078] Referring to FIGS. 2 and 3, the wall 1 is interrupted at one location by the first duct 2. In other words, the first duct 2 extends through the wall 1 in the thickness direction E of the wall 1. Therefore, the thickness direction E of the wall can be defined as the direction perpendicular to the deployment surface of the sealing film 8. Here, the thickness direction E is parallel to the vertical axis Z.

[0079] The first duct 2 is intended to pass through replacement parts of the heat insulation barrier 7, such as flat panels, single corner panels or double corner panels.

[0080] When viewed in a plane orthogonal to the vertical axis Z, the first duct 2 has a square cross-section. The first duct 2 has the shape of a right circular cylinder with a positive cross-section that unfolds along the vertical axis Z. The length of one side of the square is 1.47 m. Here, in the following, it should be understood that the term "cylinder" means a symmetric plane where the generatrices are parallel to each other, that is, a plane within a space composed of parallel straight lines. Therefore, it will be understood that the cross-section of the cylinder can be, for example, triangular, square, rectangular, polygonal, circular, or elliptical.

[0081] As shown in FIG. 3, the first duct 2 has a first opening 5 that opens to the environment outside the tank and a second opening 6 that opens to the inside of the tank. Between the first opening 5 and the second opening 6, the first duct 2 is provided with an inner surface 70.

[0082] A support flange 30 is provided above the first opening 5. The support flange 30 extends from the contour of the first opening toward the outside of the tank. The support flange 30 completely surrounds the contour of the first opening 5. Therefore, the support flange 30 has a square contour in a plane orthogonal to the thickness direction E of the wall 1.

[0083] The support flange 30 is surrounded by columns 31 evenly arranged around the entire circumference of the flange. The columns 31 extend from the outer surface 9 of the wall 1 and fit under the support flange 30 to support the flange and prevent it from bending when a load is applied to the support flange 30.

[0084] In the example shown in FIGS. 2 and 3, the second opening 6 is closed by a component 61 of the sealing film 8. This component 61 contacts the second duct 12 extending within the first duct.

[0085] This component 61 has a surface and shape that are at least equal and identical to the surface corresponding to the projection of the first duct 2 in a plane perpendicular to the thickness direction E of the wall 1. In other words, when viewed in the projection in a plane perpendicular to the thickness direction E of the wall 1, the component 61 has an area that is at least equal to the area of the first plug 10 described later. Further, when viewed in the projection in a plane perpendicular to the thickness direction E of the wall 1, the component 61 of the primary seal film 6 has at least a part thereof having the same shape as the shape of the first plug 10. In other words, the component 61 of the seal film 8 extends until it contacts the second duct 12 extending in the first duct 2, and the seal film 8 at least partially or completely closes the second opening 6 by having a part thereof facing the second opening 6.

[0086] In other words, the seal film 8 at least partially or completely closes the second opening 6 by having a part thereof facing the second opening 6.

[0087] Between the first opening 5 and the second opening 6, the inner surface 70 of the first duct 2 is defined by, for example, at least one heat insulation element 71 of the heat insulation barrier 7. This heat insulation element 71 includes glass wool or a flexible foam panel made of, for example, polyurethane or melamine.

[0088] As shown in FIGS. 2 and 3, the first duct 2 passes through the wall 1 in the thickness direction E of the wall 1. The wall of the first duct 2 is in contact with the support flange 30, the heat insulation element 71 of the heat insulation barrier 7, and the seal film 8 in the thickness direction E of the wall 1.

[0089] Referring to FIGS. 1 to 3, according to the present invention, the wall 1 is provided with a closing device 3 for closing the first duct 2. The closing device 3 includes at least one cover 11, a first plug 10, and a second duct 12.

[0090] The cover 11 closes the first opening 5 by being placed on the support flange 30. Therefore, when viewed in a plane orthogonal to the thickness direction E of the wall 1, the cover 11 has the same shape as the support flange 30. For this reason, when viewed in a plane orthogonal to the thickness direction E of the wall 1, the cover 11 has a square cross-section. Of course, such a cross-sectional shape is merely an example, and the cover has a shape similar to the cross-section of the first duct.

[0091] The cover 11 extends in an extending plane perpendicular to the vertical axis Z. The cover 11 has a through-passage 17 that provides access to the inside of the tank. Through the through-passage 17, the second duct 12 can cross the cover 11. The cover 11 and the second duct 12 are fastened to each other by welding and integrated. The welding is performed along the circumference, that is, the contour, on the outer surface of the second duct 12. Additionally or alternatively, the cover 11 and the second duct 12 can be held to each other by tightening using bolts.

[0092] The second duct 12 is intended to allow equipment such as a pump for pumping out a liquefied gas in a liquid phase or a gas phase and discharging it from the tank to pass through.

[0093] The second duct 12 has the shape of a right circular cylinder with a circular and hollow cross-section having a diameter of 0.9 m to 1.2 m. Alternatively, when viewed in a plane perpendicular to the thickness direction E of the wall, the second duct 12 can have a triangular cross-section, or a quadrangular cross-section such as a square or a rectangle.

[0094] The upper part of the second duct 12 protrudes outward from the upper surface of the cover 11 toward the outside of the tank in the thickness direction E of the tank. The upper part of the second duct 12 is provided with a first opening 15. A connection flange 40 extends in the circumferential direction across the contour of the first opening 15. Therefore, when viewed in a plane orthogonal to the thickness direction E of the wall 1, the connection flange 40 has a circular cross-section.

[0095] Here, it will be understood that the second duct 12 extends within the volume defined by the first duct 2. In other words, the second duct 12 is inscribed in the first duct 2. Therefore, when viewed in a plane orthogonal to the thickness direction E of the wall 1, the contour of the first opening 15 is inscribed in the contour of the first mouth 5, and the contour of the second opening 16 is inscribed in the contour of the second mouth 6.

[0096] On the other hand, when viewed in a plane orthogonal to the thickness direction E of the wall 1, the area of the first opening 15 is smaller than the area of the first mouth 5. And when viewed in a plane orthogonal to the thickness direction E of the wall 1, the area of the second opening 16 is smaller than the area of the second mouth 6.

[0097] The closing device 3 is arranged circumferentially with respect to the second duct and includes a plurality of reinforcing parts 41 that extend from the upper surface of the cover 11 toward the outside of the tank in the thickness direction E of the tank. The reinforcing parts 42 are evenly distributed around the upper part of the second duct 12. Each reinforcing part 41 includes a removal ring 42 that extends in the vertical direction Z from the upper surface of the reinforcing part 41. By means of these removal rings 42, the closing device 3 can be handled, for example, by a crane.

[0098] The second duct 12 includes a lower part that extends from the lower surface of the cover 11 along the vertical axis Z toward the inside of the tank. The free end of the lower part of the second duct 12 is provided with a second opening 16 that opens into the inside of the tank. Therefore, the second duct 12 defines a passage between the first opening 15 and the second opening 16.

[0099] The first plug 10 is arranged around the second duct 12 and extends from the lower surface of the cover 11 to the vicinity of the free end of the lower part of the second duct 12. In the sense that the second duct 12 is pulled out by pulling out the first plug 10, the first plug 10 can include the second duct 12.

[0100] The first plug 10 is fastened to the lower surface of the cover 11, but the peripheral portion of the lower surface is left free for positioning the support flange 30. Therefore, when the cover 11 is removed, the first plug 10 is also removed. In a plane orthogonal to the thickness direction E of the wall 1, the first plug 10 has a shape complementary to the inner surface of the first duct. When viewed in a plane orthogonal to the thickness direction E of the wall 1, the first plug 10 has, for example, a square cross section.

[0101] The first plug 10 includes a heat-insulating self-supporting panel 13. Therefore, the second duct 12 crosses the heat-insulating self-supporting panel 13. When viewed in the direction of the vertical axis Z, the lower surface of the heat-insulating self-supporting panel 13 is near the free end portion at the lower part of the second duct 12.

[0102] The heat-insulating self-supporting panel 13 includes a heat-insulating block made of rigid polyurethane and a plywood panel on which the rigid polyurethane block is placed. In an embodiment not shown, instead of the plywood panel, a composite panel or a metal panel made of, for example, aluminum or stainless steel can be used. In an embodiment not shown, the heat-insulating block made of rigid polyurethane is arranged between two plywood panels.

[0103] Alternatively, in an embodiment not shown, the heat-insulating self-supporting panel 13 is a box formed of a plywood panel, a composite panel, or a metal panel made of, for example, aluminum or stainless steel, and includes a box filled with a mineral wool such as glass wool or rock wool.

[0104] The first plug 10 may include an adhesive disposed between the heat-insulating self-supporting panel 13 and the lower surface of the cover 11. With the adhesive, adjustment along the vertical axis Z can be made, and the heat-insulating self-supporting panel 13 can be fastened to the cover 11. The adhesive can be, for example, a mastic.

[0105] In the embodiment shown in FIGS. 1 to 3, the first plug 10 also includes a mineral wool 14 such as glass wool or rock wool disposed between the second duct 12 and the heat-insulating self-supporting panel 13. The mineral wool 14 makes it possible to ensure the continuity of heat insulation between the second duct 12 and the heat-insulating self-supporting panel 13.

[0106] Referring to FIGS. 1 to 3, the closing device 3 further includes a hatch 4 for closing the first opening 15 of the second duct 2, and thus for closing the through passage 17 of the cover 11. The hatch 4 extends in an extending plane that is orthogonal to the vertical direction axis Z defined above, that is, perpendicular to the thickness direction E of the wall 1. The extending plane of the hatch 4 is parallel to the extending plane of the cover 11 and is separate therefrom.

[0107] As shown in FIG. 1, four cross struts 50 are arranged on the upper surface of the hatch 4. The cross struts 50 serve to prevent the expansion of the hatch 4 by increasing the rigidity of the hatch 4 and to maintain it in a flat state.

[0108] One of the two cross struts includes a lifting ring 51. The lifting ring 51 extends from the upper surface of the cross strut 50 along the vertical direction axis Z toward the outside of the tank. These lifting rings 51 make it possible to handle the hatch 4 using, for example, a crane.

[0109] The lower surface of the hatch 4, which is opposite to the upper surface of the hatch 4, cooperates with the connecting flange 40 so as to close the first opening 15 of the second duct 12. The hatch 4 can be mechanically connected to and / or placed on the cover 11.

[0110] Referring to FIGS. 1 to 3, the closing device 3 also includes a second plug 20. The second plug 20 has a shape complementary to the inner surface of the second duct 12. Thus, in the illustrated example, the second plug 20 is a straight circular cylinder with a circular cross section. This cross section may be equal to, for example, 8100 cm 2 or the like.

[0111] The second plug 20 is fixed to the lower surface of the hatch 4. The peripheral portion of the lower surface of the hatch 4 is left free for the connection flange 40. Therefore, when the hatch 4 is removed from the wall 1, the second plug 20 is also removed.

[0112] As shown in FIGS. 2 and 3, the second plug 20 includes a housing 24. The housing 24 is defined by the hatch 4 and a plywood panel 22 connected to the hatch 4 by a plurality of rods 23, specifically four rods 23, along the vertical axis Z. When viewed in a plane orthogonal to the vertical axis Z, the plywood panel 22 has a circular cross section.

[0113] In an embodiment not shown, instead of the plywood panel 22, a composite panel or a metal panel made of, for example, aluminum or stainless steel may be used.

[0114] The heat insulating material 25 is disposed within the housing 24. The heat insulating material 25 is composed of a polyurethane foam. This polyurethane foam may be reinforced with glass fibers. Alternatively, the heat insulating material 25 may be composed of, for example, mineral wool such as glass wool or rock wool.

[0115] Referring to FIG. 2, the first duct 2 is closed by a cover 11. The peripheral portion of the lower surface of the cover 11 is disposed on the support flange 30. In order to maintain the cover 11 on the support flange 30, bolts (not shown) are disposed on the outer periphery of the support flange 30, and the cover 11 is maintained against this support flange 30 by tightening.

[0116] Since the first plug 10 is fixed to the cover 11, the first plug 10 is disposed within and closes the first duct 2. The first plug 10 extends from the lower surface of the cover 11 to the second opening 6 of the first duct 2. Further, the first plug 10 extends radially from the inner surface of the first duct 2 to the second duct 12 and surrounds the second duct 12. In other words, the first plug 10 is in contact with the inner surface of the first duct 2 via the heat-insulating self-supporting panel 13. Therefore, there is no space between the inner surface of the first duct 2 and the heat-insulating self-supporting panel 13 of the first plug 10.

[0117] The component of the seal film 8 facing the first plug 10 is fixed to the lower surface of the heat-insulating self-supporting panel 13 of the first plug 10. The component 61 of the seal film 8 faces the lower part of the second duct 12. A part of the second duct 12 protrudes into the tank along the vertical axis Z with respect to the film component 61. This film component 61 is fixed to the second duct 12 by, for example, an attached angle iron.

[0118] To close the second duct 12, the peripheral edge of the lower surface of the hatch 4 is placed on the connection flange 40. The hatch 4 is locked to the connection flange 40 by a bolt (not shown) that maintains the state of pressing the hatch 4 against the connection flange 40.

[0119] As shown in FIG. 2, the second plug 20 extends inside the second duct 12. Therefore, the plywood or metal panel 22 is in the same plane as the second opening 16 of the second duct 12. Thereby, the heat insulating material 25 extends over the entire length of the lower part of the second duct 12 measured along the thickness direction E of the wall 1. For this reason, the second plug 20 is separated from the first plug 10 by the second duct 12.

[0120] Reference numeral 60 shown in FIGS. 2 and 3 indicates the cutting line of the seal film 8. If the introduced component is too bulky to pass through the second duct 12, the seal film 8 is cut to pull out the first plug 10, but the cutting must follow this cutting line 60. When closing the first duct 2 after repositioning the cover 11 with the first plug 10, this mark can be seen when welding the component 61 of the seal film 8 back to the remaining part of the seal film 8.

[0121] The above-described technique for manufacturing a tank having a single seal film can be utilized for various types of storage tanks, for example, to form a double-film tank for liquefied natural gas (LNG) in onshore facilities or floating devices such as methane tankers. Therefore, the tank using the wall of the present invention can be intended for transporting cryogenic fluids. Alternatively or additionally, the tank according to the present invention can be a storage tank that houses a cryogenic fluid used as fuel for tanker installation.

[0122] The seal film 8 shown in FIGS. 1 to 3 is a primary seal film, and the heat insulation barrier 7 is a primary heat insulation barrier. It can be considered that a secondary heat insulation barrier and a secondary seal film can be additionally provided between the wall of the support structure and the primary insulation barrier. The secondary seal film is disposed in contact with the secondary insulation barrier, the primary insulation barrier is disposed in contact with the secondary seal film, and the primary seal film is disposed in contact with the primary insulation barrier. Since the primary seal film 8 has corrugated portions, it is a corrugated seal film.

[0123] Therefore, the present technology can also be applied to a plurality of heat insulation barriers and a plurality of stacked seal films.

[0124] Due to the dimensions of the hatch 4, this can also be referred to as a manhole. Due to the dimensions of the first duct 2, this can also be referred to as an equipment hole.

[0125] In addition to petroleum gas, the liquefied gas can be liquefied natural gas, liquid ethane, liquid propane, liquid argon, liquid ammonia, liquid hydrogen. These fluids are cryogenic fluids.

[0126] Next, a method for providing access to the interior of an emptied tank with an upper wall constructed in accordance with the embodiments described and illustrated in FIGS. 1-3 will be described. This method may require removing bolts (not shown) that hold the hatch 4 to the connection flange 40. Next, the crane can lift the hatch 4 by its lifting ring 51. If the hatch 4 and the second plug 20 are fixed to each other, removing the hatch 4 makes it possible to also remove the second plug 20, releasing the passage formed by the second duct 12. This allows access to the interior of the tank from the outside of the tank. Thus, small equipment can be passed through, or a discharge pump can be used, or maintenance work can be carried out by a person.

[0127] To close the second duct 12 again, use a crane to relocate the hatch 4 and the second plug 20 to their initial positions and tighten the bolts again to keep the hatch 4 fastened to the connection flange 40.

[0128] For example, if it is desired to pass larger equipment through to replace components that make up the primary or secondary seal membrane inside the tank, the method may include the step of separating the seal membrane 8 from the plywood panel of the heat-insulating self-supporting panel 13 of the first plug 10. This step consists of cutting the part 61 of the seal membrane 8 along the cutting line 60 and separating this part 61 from the free end of the second duct 12 that opens into the internal volume of the tank.

[0129] This step is carried out after, or before, removing the bolts (not shown) that hold the cover 11 of the closing device 3 to the support flange 30. Then, the cover 11 can be lifted by the crane via its removal ring 41. If the cover 11 and the first plug 10 are fixed to each other, removing the cover 11 allows the first plug 10, and thus the entire closing device, to be removed. Consequently, the first duct 2 of the wall 1 is completely freed, so that the components forming the sealing film 8 can be introduced or withdrawn.

[0130] Once the work carried out inside the tank is finished and the first duct 2 is to be closed again, with the cover 11 placed on the support flange 30, the closing device 3 is returned to the first duct 2. The cover 11 is locked to the support flange 30 using bolts. Then, the component 61 of the sealing film 8 is welded again to the rest of the sealing film 8. Alternatively, a closing panel forming a repair part similar to the component 61 of the sealing film 8 can also be used. In an embodiment not shown, the closing panel can be composed of a plurality of pre-assembled pieces or pieces assembled after being introduced into the tank.

[0131] Finally, the hatch 4 with the second plug 20 is placed on the connection flange 40 and fastened with bolts.

[0132] The wall which is the subject of the present invention is not limited in any way to the described shape, dimensions, and position. Naturally, the wall can be, for example, a horizontal tank wall or a transverse tank wall.

[0133] Naturally, the present invention is not limited to the above examples and many modifications can be made to these examples without departing from the scope of the present invention.

Claims

1. A wall (1) of a tank for storing and / or transporting liquefied gas, a duct (2) passing through the wall (1) in the thickness direction (E) of the wall (1), a closing device (3) configured to close the duct (2), In the wall (1) provided with, the closing device (3) comprises at least one hatch (4) configured to provide access to the interior of the tank, the duct (2) comprises a first opening (5) configured to open to the environment outside the tank and a second opening (6) configured to open to the interior of the tank, the closing device (3) comprises a cover (11) for closing the first opening (5), the cover (11) has a through passage (17) for providing access to the interior of the tank, the hatch (4) is configured to close the through passage (17), Wall (1).

2. The cover (11) and the hatch (4) each extend in a different plane, The wall (1) according to claim 1.

3. The duct (2) is a first duct, the closing device (3) comprises a first plug (10) and a second plug (20), at least a part of the first plug (10) extends through a layer of the wall (1) and is adjacent to the inner surface of the first duct (2), at least a part of the second plug (20) extends through the layer of the wall (1) inside the first duct (2), The first plug (10) and the second plug (20) are separated by a second duct (12), The wall (1) according to claim 1 or 2.

4. At least a part of the second plug (20) has a shape complementary to the inner surface of the second duct (12). The wall (1) according to claim 3.

5. The second plug (20) and the hatch (4) are fixed to each other. The wall (1) according to any one of claims 3 and 4.

6. The second plug (20) includes a heat insulating material (25) extending in the second duct (12). The length of the heat insulating material (25) measured along the thickness direction (E) of the wall (1) is at most the same as the length of the second duct measured along the thickness direction (E) of the wall (1). The wall (1) according to any one of claims 3 to 5.

7. At least a part of the first plug (10) has a shape complementary to the inner surface of the duct (2). The wall (1) according to any one of claims 3 to 6.

8. The first plug (10) and the cover (11) are fixed to each other. The wall (1) according to any one of claims 3 to 7.

9. The first plug (10) includes at least one heat insulating self - standing panel (13) disposed around the second duct (12). The wall (1) according to any one of claims 3 to 8.

10. The cover (11) and the second duct (12) are firmly connected to each other. The wall (1) according to any one of claims 3 to 9.

11. The second duct (12) passes through the cover (11) via the through - passage (17) of the cover (11). The wall (1) according to any one of claims 3 to 10.

12. In the thickness direction (E) of the wall (1), the upper part of the second duct (12) protrudes from the cover (11) toward the outside of the tank. The wall (1) according to any one of claims 3 to 11.

13. The wall (1) includes, in the thickness direction thereof, at least one heat insulation barrier (7) and at least one sealing film (8) intended to contact the liquefied gas present in the tank. The sealing film (8) faces at least partially the duct (2) in the thickness direction (E) of the wall (1). The wall (1) according to any one of claims 1 to 12.

14. A tank for storing and / or transporting liquefied gas, comprising at least one wall (1) according to any one of claims 1 to 13.

15. A method for providing access to the inside of a tank for storing and / or transporting liquefied gas, comprising at least one wall (1) according to any one of claims 3 to 12 in combination with claim 13, the method comprising: removing the second plug (20) to access the inside of the tank; cutting a part of the sealing film (8) around the closing device (3); removing the closing device (3). The method comprising the above steps.

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