LNG ship independent liquid cargo tank side vertical surface fixing device and fixing method

Abstract

The present application relates to the field of LNG ship manufacturing, and particularly relates to a side vertical surface fixing device and fixing method for an independent liquid cargo tank of an LNG ship. The side vertical surface fixing device for the independent liquid cargo tank of the LNG ship comprises a first edge limiting assembly for being welded and fixed on the four peripheral edges of the liquid cargo tank, and a second edge limiting assembly for being welded and fixed on the four peripheral edges of the liquid cargo tank, one of the first edge limiting assembly and the second edge limiting assembly is a double-layer plate assembly arranged at intervals, and the other is a single plate structure inserted into the gap of the double-layer plate assembly, and the center surface of the first edge limiting assembly and the second edge limiting assembly passes through the centroid of the liquid cargo tank. The fixing device can effectively limit without affecting the cold shrinkage deformation, thereby solving the problem that the liquid cargo tank will shrink inward after loading the ultra-low temperature cargo, resulting in the cold shrinkage stress and the continuous stress of the liquid cargo tank, and even leading to the limiting failure.

Description

Technical Field

[0001] This invention relates to the field of LNG ship manufacturing, and in particular to a fixing device and method for fixing the side facade of an independent liquid cargo tank on an LNG ship. Background Technology

[0002] Currently, commonly used LNG carriers employ independent cargo tanks located within cargo tanks, with the tank's sidewalls spaced apart from the cargo tank's sidewalls. To secure the cargo tank and prevent swaying or displacement, a connecting structure is installed between the tank and the cargo tank. Existing technology often uses welded connecting stiffeners to fix the cargo tank, with both ends welded to the cargo tank and cargo tank respectively. However, in actual use, the cargo tank needs to hold -163°C cryogenic LNG cargo. Under the influence of low temperatures, the cargo tank will contract inwards, causing the connecting stiffeners between the tank and cargo tank to be continuously stressed. This hinders stress release from the cargo tank and can even lead to the weld points between the connecting stiffeners and the cargo tank or cargo tank breaking, resulting in the failure of the limiting mechanism. Summary of the Invention

[0003] In view of this, the present invention provides a side-mounted fixing device for an independent liquid cargo tank of an LNG ship, which solves the problem in the prior art that the liquid cargo tank will shrink inward after loading cryogenic cargo, resulting in cold shrinkage stress that causes the liquid cargo tank to be continuously stressed, and even leading to limit failure; the present invention also provides a fixing method for an independent liquid cargo tank of an LNG ship, which solves the above-mentioned technical problems.

[0004] A side-mounted fixing device for an independent cargo tank on an LNG carrier includes a first edge-limiting assembly for welding and fixing to the four edges of the cargo tank, and a second edge-limiting assembly for welding and fixing to the four edges of the cargo tank. One of the first and second edge-limiting assemblies is a double-layered plate assembly arranged at intervals, and the other is a single-plate structure inserted into the gap of the double-layered plate assembly. The center plane of the double-layered plate assembly is defined as the surface located at the center of the double-layered plate assembly and making the two plates symmetrical to each other. The center plane of the single-plate structure is defined as the surface parallel to its plate surface. The center planes of the first and second edge-limiting assemblies pass through the centroid of the cargo tank, so that the first and second edge-limiting assemblies slide relative to each other when the cargo tank shrinks and deforms inward.

[0005] Furthermore, a first side limiting component is provided on the side of the liquid cargo tank, and a second side limiting component is provided on the side of the liquid cargo compartment. One of the first side limiting component and the second side limiting component is a double-layer plate assembly arranged at intervals, and the other is a single-plate structure inserted into the gap of the double-layer plate assembly. The surface located at the center of the double-layer plate assembly and making the two plates symmetrical to each other is defined as its center surface. The symmetrical surface of the single-plate structure parallel to its plate surface is defined as its center surface. The center surfaces of the first side limiting component and the second side limiting component pass through the centroid of the liquid cargo tank, so that when the liquid cargo tank shrinks and deforms inward, the first edge limiting component and the second edge limiting component slide relative to each other.

[0006] Furthermore, the first side limiting component and the first edge limiting component are single-plate structures, while the second side limiting component and the second edge limiting component are double-layer plate components.

[0007] Furthermore, the single-board structure and the double-layer board assembly are arranged alternately, and the spacing between the double-layer board assemblies is 0.5-0.8 mm larger than the thickness of the single-board structure.

[0008] The beneficial effects of the LNG carrier independent cargo tank side facade fixing device in this invention are as follows: In this invention, the cargo tank is fixed by a first edge-limiting component fixed around its perimeter and a second edge-limiting component located on the tank wall. Since the cargo tank's size changes before and after loading cryogenic cargo, resulting in relative shrinkage and deformation, the relatively sliding first and second edge-limiting components do not affect this shrinkage. Furthermore, because the cargo tank tends to shrink uniformly towards its centroid during contraction, the device located on the side facade of the LNG carrier independent cargo tank provides a more effective fixation mechanism. The limiting component with its edge and center surface passing through the centroid does not affect its contraction towards the centroid. Furthermore, since the first edge limiting component and the second edge limiting component are interlocked, after the contraction is completed, the inclined limiting component will still form a good limiting between the liquid cargo tank and the liquid cargo compartment. That is, the fixing device can effectively limit the liquid cargo without affecting its cold contraction deformation, thereby solving the problem in the prior art that the liquid cargo tank will contract inward after loading cryogenic cargo, resulting in cold contraction stress that causes the liquid cargo tank to be continuously stressed, or even leading to the failure of the limiting component.

[0009] Furthermore, the first and second side limiting components facilitate better fixation on the sides. Since the sides are flat, it is easier to maintain strong welding strength, thereby enhancing the limiting effect on the liquid cargo tank.

[0010] Furthermore, by maintaining a gap fit between the single-panel structure and the double-panel assembly, installation is convenient; at the same time, it also allows for better sliding fit during cold contraction.

[0011] Furthermore, by arranging a single-plate structure on the liquid cargo tank, it is easier to reduce the damage of welding to the uniform material of the liquid cargo tank, making it easier to deform towards the centroid during cold shrinkage deformation.

[0012] A method for securing an independent cargo tank on an LNG carrier, using the aforementioned securing device, firstly, determines that the center position of the cargo tank to be installed is located within the cargo tank. A laser line projector is placed at this position and projects a laser line onto the cargo tank wall at the location where the single-plate structure or double-layer plate assembly will be installed. The single-plate structure or double-layer plate assembly is welded and secured according to the laser line's indication. After securing the cargo tank wall, the cargo tank is hoisted and moved into the cargo tank, maintaining the center position of the cargo tank at a specific location within the cargo tank. Then, the corresponding single-plate structure or double-layer plate assembly is placed in place on the cargo tank, and the aforementioned components are welded to the cargo tank.

[0013] Furthermore, the liquid cargo tank is equipped with a single-plate structure.

[0014] Furthermore, when welding and fixing the double-layer board assembly, the spacing between the double-layer boards should be 0.5-0.8 mm greater than the thickness of the single-layer board structure.

[0015] The beneficial effects of the LNG carrier independent cargo tank fixing method of this invention are as follows: When fixing the LNG carrier independent cargo tank, the above-mentioned fixing device is used. Since it is necessary to maintain the interlocking fit between the single-plate structure and the double-layer plate assembly, multiple such fixing devices are arranged around the outer perimeter of the cargo tank. Furthermore, multiple sets of devices need to ensure that their center plane passes through the centroid of the cargo tank. A laser projection device is used to project and indicate their preset positions, facilitating the maintenance of the orientation of their center plane. First, the fixing devices on the cargo tank wall are fixed, and then the cargo tank is hoisted. When the cargo tank is lowered into the cargo tank, no dryness is generated. This design facilitates the lowering of the liquid cargo tank. After the liquid cargo tank is lowered, the welding of the fixing structure on the liquid cargo tank can be carried out. Since the fixing device on the liquid cargo tank already exists, the fixing device on the liquid cargo tank does not need to be positioned again, which reduces the welding difficulty. After welding, the first edge limiting component and the second edge limiting component can limit the position of the liquid cargo tank without affecting the cold shrinkage deformation of the liquid cargo tank. This solves the problem in the prior art that the liquid cargo tank will shrink inward after loading cryogenic goods, resulting in cold shrinkage stress that causes the liquid cargo tank to be under continuous stress, and even causing the limiting component to fail.

[0016] Furthermore, by maintaining a gap fit between the single-panel structure and the double-panel assembly, installation is convenient; at the same time, it also allows for better sliding fit during cold contraction.

[0017] Furthermore, by arranging a single-plate structure on the liquid cargo tank, it is easier to reduce the damage of welding to the uniform material of the liquid cargo tank, making it easier to deform towards the centroid during cold shrinkage deformation. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a top view of an independent liquid cargo tank fixed inside a liquid cargo tank in an LNG ship according to the present invention; Figure 2 for Figure 1 View from AA direction; Figure 3 This is a front view of an embodiment of the LNG ship independent cargo tank side facade fixing device of the present invention; Figure 4 This is a front view of an embodiment of the LNG ship independent cargo tank side facade fixing device of the present invention; Figure 5 This is a front view of an embodiment of the LNG ship independent cargo tank side facade fixing device of the present invention.

[0020] The labels in the diagram represent: 1. Liquid cargo tank; 2. Liquid cargo compartment; 21. Centroid; 31. Single-plate structure; 32. Double-layer plate assembly. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0022] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The singular forms “a,” “the,” and “the” as used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0023] It should be understood that although the terms first, second, third, etc., may be used in this disclosure to describe various information, such information should not be limited to these terms and should not be construed as indicating or implying relative importance. These terms are used only to distinguish information of the same type from one another. For example, without departing from the scope of this disclosure, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0024] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0025] In the description of this invention, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "linking" should be interpreted broadly. For example, they can refer to mechanical or electrical connections, or internal connections between two components. They can be direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0026] In the following description, suffixes such as "module," "part," or "unit" used to denote elements are used only for the convenience of the description of the invention and have no specific meaning in themselves. Therefore, "module" and "part" can be used interchangeably.

[0027] To better understand the technical solution of the present invention, the present invention will be described in detail below with reference to the accompanying drawings.

[0028] In Embodiment 1 of the LNG ship independent cargo tank side facade fixing device (hereinafter referred to as cargo tank fixing device) of the present invention: In this embodiment, the independent device for the liquid cargo tank is set with a single plate structure and a double-layer plate structure, which are respectively set on the liquid cargo tank and the liquid cargo compartment, so that the liquid cargo tank is not affected by the cold shrinkage deformation while limiting the position.

[0029] like Figure 1 and Figure 2As shown, in this embodiment, limiting structures for limiting the liquid tank 1 are provided on the four edges and the center of the side. Specifically, the structure on the four edges is a first edge limiting component, and the structure on the side of the liquid tank 1 is a first side limiting component. The first edge limiting component and the first side limiting component have the same structure, which is a single plate structure 31. The single plate structure 31 is a metal plate, and its height is less than the height of the liquid tank 1. For the single plate structure 31, the symmetrical plane parallel to its plate surface is defined as its center plane. The center planes of the first edge limiting component and the first side limiting component both pass through the centroid 11 of the liquid tank 1.

[0030] like Figure 1-5 As shown, correspondingly, a second edge-limiting component adapted to the first edge-limiting component is provided on the vertically arranged edges of the liquid cargo tank 2, and a second side-limiting component adapted to the first side-limiting component is provided on the vertically arranged sides of the liquid cargo tank 2. Both the second edge-limiting component and the second side-limiting component are double-layer plate assemblies 32, which include parallel and spaced double-layer metal plates with a gap between them to accommodate the single-plate structure 31. Accordingly, the surface located at the center of the double-layer plate assembly 32 and making the two plates symmetrical to each other is defined as its center surface. The center surfaces of the second edge-limiting component and the second side-limiting component also pass through the centroid 11 of the liquid cargo tank 1.

[0031] The above-described configuration allows the first edge limiting component to move relative to the second edge limiting component towards the centroid 11, and the first side limiting component to move relative to the second side limiting component towards the centroid 11. To enable better relative movement between the single-plate structure 31 and the double-layer plate assembly 32 in the fixing device, this embodiment maintains a spaced arrangement between the single-plate structure 31 and the double-layer plate assembly 32. The distance between the double-layer plate assemblies 32 is 0.5-0.8 mm greater than the thickness of the single-plate structure 31. When the single-plate structure 31 is inserted into the double-layer plate assembly 32, the friction is reduced during relative sliding due to the gap. Furthermore, because the gap is kept small (only 0.5-0.8 mm), it is less likely to cause swaying or other directional displacements when limiting the liquid tank 1.

[0032] Of course, in other embodiments, the gap can be set to other sizes; or, in other embodiments, the first edge limiting component and the first side limiting component can be set as double-layer plates, and the second edge limiting component and the second side limiting component can be set as single-layer plates, but in this case, their respective center surfaces must still pass through the centroid of the liquid tank.

[0033] In Embodiment 1 of the LNG ship independent cargo tank fixing method (hereinafter referred to as the cargo tank fixing method) of the present invention: The fixing device used in this embodiment is the structure in the side facade fixing device of the independent cargo tank 1 of the LNG ship. Since there are four first edge limiting components and four first side limiting components around the cargo tank 1, these eight single plate structures 31 need to be adapted to the eight double-layer plate components 32 on the cargo tank 2 at the same time, and their respective center lines all point to the centroid 11 of the cargo tank 1.

[0034] Specifically, during installation, firstly, the position of the liquid cargo tank 1 within the liquid cargo compartment 2 is determined, and the center position of the liquid cargo tank 1 is marked. The corresponding placement position of the centroid 11 of the liquid cargo tank 1 on the liquid cargo compartment 2 is then determined. Next, a laser projector is placed at this position, projecting laser lines to the four sides and four corners. The second edge limiting component and the second side limiting component are installed according to the laser line indication. Since both the second edge limiting component and the second side limiting component are double-layered plates, sufficient gaps should be maintained between the two metal plates in the double-layered plate assembly 32 during installation. In this embodiment, this gap is the thickness of the single-plate structure 31 plus 0.5-0.8 mm. Then, the first edge limiting component and the first side limiting component on the liquid cargo tank 1 need to be installed. Specifically, the single-plate structure 31 is placed at the center of the double-layered plate assembly 32, maintaining contact between the single-plate structure 31 and the liquid cargo tank 1. Finally, the single-plate structure 31 and the liquid cargo tank 1 are welded and fixed together.

[0035] Of course, in other implementations, the positions of the single-plate structure and the double-plate assembly can be reversed. In this case, the structure on the liquid cargo tank is still welded and fixed first, and then the liquid cargo tank is hoisted into the liquid cargo tank before the components on the liquid cargo tank are welded and fixed.

[0036] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A fixing device for the side facade of an independent cargo tank on an LNG ship, characterized in that: The device includes a first edge-limiting assembly for welding and fixing to the four edges of the liquid cargo tank, and a second edge-limiting assembly for welding and fixing to the four edges of the liquid cargo tank. One of the first edge-limiting assembly and the second edge-limiting assembly is a double-layer plate assembly arranged at intervals, and the other is a single-plate structure inserted into the gap of the double-layer plate assembly. The center plane of the double-layer plate assembly is defined as the surface located at the center of the double-layer plate assembly and making the two plates symmetrical to each other. The center plane of the single-plate structure parallel to its plate surface is defined as its center plane. The center planes of the first edge-limiting assembly and the second edge-limiting assembly pass through the centroid of the liquid cargo tank so that the first edge-limiting assembly and the second edge-limiting assembly slide relative to each other when the liquid cargo tank is cold-shrinking and deformed inward.

2. The LNG ship independent cargo tank side facade fixing device according to claim 1, characterized in that: A first side limiting component is also provided on the side of the liquid cargo tank, and a second side limiting component is also provided on the side of the liquid cargo compartment. One of the first side limiting component and the second side limiting component is a double-layer plate assembly arranged at intervals, and the other is a single plate structure inserted into the gap of the double-layer plate assembly. The surface located at the center of the double-layer plate assembly and making the two plates symmetrical to each other is defined as its center surface. The symmetrical surface of the single plate structure parallel to its plate surface is defined as its center surface. The center surfaces of the first side limiting component and the second side limiting component pass through the centroid of the liquid cargo tank, so that when the liquid cargo tank shrinks and deforms inward, the first edge limiting component and the second edge limiting component slide relative to each other.

3. The LNG ship independent cargo tank side facade fixing device according to claim 2, characterized in that: The first side limiting component and the first edge limiting component are single-plate structures, while the second side limiting component and the second edge limiting component are double-layer plate components.

4. The LNG ship independent cargo tank side facade fixing device according to any one of claims 1-3, characterized in that: The single-layer structure and the double-layer board assembly are arranged alternately, and the spacing between the double-layer board assembly is 0.5-0.8 mm larger than the thickness of the single-layer structure.

5. A method for securing independent cargo tanks on an LNG carrier, characterized in that: Using the fixing device described in any one of claims 1-4, first determine that the center position of the liquid cargo tank to be installed is located in the liquid cargo tank. Place the laser line projector at this position and project a laser line onto the position on the tank wall where the single-plate structure or double-layer plate assembly is to be installed. Weld and fix the single-plate structure or double-layer plate assembly according to the laser line indication. After the tank wall is fixed, hoist the liquid cargo tank into the liquid cargo tank, keeping the center position of the liquid cargo tank in a specific position in the liquid cargo tank. Then, place the corresponding single-plate structure or double-layer plate assembly on the liquid cargo tank into place and weld the above components to the liquid cargo tank.

6. The method for securing independent cargo tanks on LNG carriers according to claim 5, characterized in that: The liquid cargo tank is equipped with a single-plate structure.

7. The method for securing independent cargo tanks on LNG carriers according to claim 5 or 6, characterized in that: When welding and fixing the double-layer board assembly, keep the spacing between the double-layer boards 0.5-0.8mm greater than the thickness of the single-layer board structure.

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