JP3640094B2 - Low temperature tank bottom plate installation method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for installing a bottom plate of a cryogenic tank.
[0002]
[Prior art]
Conventionally, a bottom plate 3 is installed in a low temperature tank such as an LNG tank by the method illustrated in FIG. That is, first, (A) a cold insulation material 1 such as urethane foam is laid on the bottom surface for keeping the bottom of the low temperature tank, a curing plate for protecting the cold insulation material is laid thereon, and a base plate assembly base is further provided thereon. Put 2 on it. Next, (B) a steel plate for the bottom plate 3 is laid and welded (mainly butt welding) on the gantry, and inspection of the welded portion (radiation inspection, X-ray inspection, etc.) is performed. Thereafter, (C) the suspension metal fitting 4 is temporarily attached to the upper surface of the bottom plate 3, the bottom plate 3 is lifted by using a number of wires 5, (D) the mount 2 is removed, and the bottom plate 3 is suspended above the cold insulation material. It was.
[0003]
However, in the above-described method for installing the bottom plate of the cryogenic tank, after the installation, welding, and inspection of the bottom plate of (B), temporary attachment / removal of the hanging metal fitting 4 and the setting of a large number of wires 5 shown in (C) and (D) Etc. were required, and there were many problems at high places and low work efficiency.
In order to solve this problem, a "tank bottom plate installation method" (Japanese Patent Laid-Open No. 4-171400), a "low temperature tank bottom plate construction method" (Japanese Patent Laid-Open No. 4-321898) and the like have already been filed. .
[0004]
Japanese Patent Application Laid-Open No. 4-171400 has a bottom plate installation method in which a plurality of pearlite concrete blocks including an outer cylinder and an inner cylinder that is inserted into the outer cylinder so as to be movable up and down are interposed between the foundation slab and the tank bottom plate, Next, pressurized air is fed into the outer cylinder below the inner cylinder, the tank bottom plate is raised through the inner cylinder, a work space is formed between the tank bottom plate and the foundation slab, and then the predetermined operation is performed. The air in the cylinder is evacuated, the inner cylinder and the tank bottom plate are lowered, and the tank bottom plate is installed on the foundation slab. However, in this construction method, (1) it is necessary to install a large number of outer and inner cylinders through the cold insulation material, which not only deteriorates the cold insulation performance at the bottom of the bottom plate, but also (2) uses the conventional frame as it is. Since it was not possible, there was a problem that the work efficiency of laying, welding, inspection, etc. of the bottom plate deteriorated.
[0005]
Further, in the method for constructing a bottom plate disclosed in Japanese Patent Laid-Open No. 4-321898, a bottom plate is lifted and hung by assembling and welding most of the bottom plate constituent members previously arranged in an elongated rectangular shape on a bottom cold insulator having a concave groove. Arranged so that the welding line between the bottom plate blocks that have been welded into large blocks is positioned above the concave groove in the bottom cold insulation material, and backed by a carriage that runs in this concave groove It is used for loading and unloading of gold and radiation inspection film. However, in this method, (3) since the grooved groove is provided in the cold insulation material, not only the cold insulation performance at the bottom of the bottom plate is deteriorated, but also (4) the bottom plate shape is greatly restricted and (5) a complicated cart with a structure There was a problem such as needing.
[0006]
[Problems to be solved by the invention]
The present invention has been developed to solve the above-described problems. That is, the object of the present invention is to eliminate the work of high places and inefficiency work such as temporary attachment / removal of hanging metal fittings, setting of wires and the like, and the cold insulation performance at the bottom of the bottom plate using the conventional cold insulation material as it is. Can be kept high, and the work efficiency of laying, welding, inspection, etc. of the bottom plate can be efficiently performed by using the conventional base as it is, and there are few restrictions on the shape of the bottom plate, and complicated equipment is unnecessary. An object of the present invention is to provide a method for installing a bottom plate of a low temperature tank.
[0007]
[Means for Solving the Problems]
According to the present invention, a cold insulation material is laid on the bottom surface, a plurality of bases for assembling the bottom plate are placed on the cold insulation material, a steel plate for the bottom plate is laid and welded on the stand, and the bottom plate of the low temperature tank for inspecting the welded portion In the installation method, (a) the periphery and bottom surface of the bottom plate are hermetically connected by a flexible sheet material to form an airtight space below the bottom plate, (b) a weight is installed on the bottom plate, and then , Supplying pressurized air to the airtight space through the flexible sheet material, supporting the bottom plate with the pressurized air, and (c) removing the mount via the air chamber type passage provided in the flexible sheet. Te, supporting the bottom plate only pressurized air, then (d), remove the pressurized air, a method of installing a base plate on cold material, before the supply of the pressurized air, the weight on the bottom plate a bottom plate mounting process of cold tank, characterized in that to prevent the bulging of the bottom plate by placing the It is subjected.
[0008]
According to this method, it is necessary to attach a fixing piece around the bottom plate when the flexible sheet material (a) is set. This is a work that can be easily and efficiently performed, and can eliminate the work of high places and inefficiency work such as temporary attachment / removal of hanging brackets and setting of wires. Also, laying, welding, and inspection of the bottom plate are exactly the same as before, and the conventional cold insulation material can be used as it is to keep the cold insulation performance at the bottom of the bottom plate high, and work can be done using the conventional stand as it is. Efficiency can be performed efficiently. Furthermore, there is almost no restriction on the shape of the bottom plate except that in (a) it is necessary to attach a flexible sheet around the bottom plate. Moreover, although an air chamber type channel | path is required as an apparatus, since pressurized air acts on the whole lower surface of a bottom plate, the pressure of pressurized air is very low (for example, when a bottom plate is 1 cm thickness, about 100 mmAq), A simple double-door air chamber passage is sufficient. In (b) , since the weight is placed on the bottom plate and the pressurized air is supplied to the airtight space, the bottom plate can be prevented from swelling.
[0009]
Further, the weight is preferably a hollow container that can be filled with water and has a flat bottom surface. By using this hollow container, the installation and removal of the weight can be further facilitated.
[0010]
Further, before forming the airtight space, a part of the gantry is replaced with an air bag that can be expanded and contracted by internal pressure and attached with a pull-out rope, and after supplying pressurized air, the air chamber type passage is used. Thus, it is preferable to replace the entire pedestal with the airbag, and after removing the pedestal, remove the airbag by pulling the pull-out rope through the air chamber passage. Thereby, the air bag can be efficiently removed without pulling a person under the bottom plate by pulling the pull-out rope.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected and used for the common part in each figure.
FIG. 1 is a schematic diagram of a method for installing a bottom plate of a cryogenic tank according to the present invention. In this figure, as shown in FIG. 1 (A), the method of the present invention lays a cold insulation material 1 on the bottom surface, places a plurality of bases 2 for assembling the bottom plate on the cold insulation material 1, and places the bottom plate on the base 2. The first step of laying and welding the steel plate for 3 and inspecting the welded portion and the periphery and bottom surface of the bottom plate 3 are hermetically connected by the flexible sheet material 11 as shown in FIG. Then, as shown in FIG. 1 (C), the second step of forming an airtight space below the bottom plate 3, and pressurized air is supplied to the airtight space through the flexible sheet material 11. As shown in FIG. 1 (D), the fourth step of supporting the bottom plate 3 by removing the gantry 2 and supporting the bottom plate 3 only by the pressurized air, and then removing the pressurized air, as shown in FIG. And a fifth step of installing 3 on the cold insulator 1.
[0012]
The laying of the cold insulation material 1 and the laying / welding / inspection of the bottom plate 3 in the first step of FIG. 1 (A) are exactly the same as conventional ones, and the conventional cold insulation material 1 is used as it is to improve the cold insulation performance at the bottom of the bottom plate. The work efficiency can be efficiently performed using the conventional gantry 2 (for example, a frame scaffold) as it is. Accordingly, the pedestals 2 can be arranged freely, and may be arranged densely as shown in FIG. 1A, or may be arranged with an interval if necessary. Also, as in the conventional welding inspection, radiation inspection, X-ray inspection, etc. can be applied as they are.
[0013]
In the second step of FIG. 1 (B), before the airtight space is formed, for example, the gantry 2 at the part where the X-ray inspection has been completed is removed, and an air bag 12 that can be vertically expanded and contracted by internal pressure is installed instead. preferable. As shown in FIG. 2, the air bag 12 is a cylindrical hollow container made of leather, synthetic leather, flexible plastic, rubber or the like, and is provided with a reinforcing ring inside, and pressurized air inside. Etc., it can be expanded and contracted up and down like bellows. Further, a pull-out rope 12 a and a pressurizing air hose 12 b are attached to the airbag 12. By supplying pressurized air into the airbag 12 through the pressurizing air hose 12b, the airbag 12 can be extended in the vertical direction to have the same height as the gantry 2 and can be used instead of the gantry. Further, the air bag 12 can be pulled out without entering a person under the bottom plate 3 by pulling out the pressurized air to contract the air bag 12 and pulling the pull-out rope 12a. With this configuration, the gantry 2 can be efficiently and easily removed while the bottom plate 3 is supported by the airbag 12.
[0014]
FIG. 3 is an enlarged view of a portion A in FIG. The flexible sheet material 11 that hermetically connects the periphery and bottom surface of the bottom plate 3 is a ring-shaped flexible member formed of, for example, rubber, a plastic sheet, or the like. The entire circumference is airtightly attached to the upper peripheral surface of the bottom plate 3 with a fixing piece 13 shown in FIG. Further, the entire periphery of the outer end portion of the sheet material 11 is airtightly attached to a ring-shaped annular plate 7 (see FIG. 1) provided around the bottom surface of the low-temperature tank by a similar fixing piece (not shown). ing. With this configuration, the flexible sheet material 11 is hermetically connected between the periphery of the bottom plate 3 and the bottom surface like a skirt of a hovercraft, thereby forming an airtight space below the bottom plate 3. Hereinafter, the flexible sheet material 11 is referred to as a skirt.
[0015]
Further, as shown in FIG. 3, an air hose 11a for supplying pressurized air is attached to a part of the skirt 11, and the pressurized air is introduced into the airtight space below the bottom plate 3 through the air hose 11a. Or extra pressurized air can be removed from another air hose 11a, whereby the pressure in the airtight space below the bottom plate can be set freely.
[0016]
FIG. 4 is a schematic plan view of FIG. As shown in this figure, air chamber type passages 15 are provided at a plurality of locations on the side surface of the skirt 11. The air chamber type passage 15 is disposed in a working opening provided in the low temperature tank. The air chamber type passage 15 is a chamber having, for example, a double door, and the pressure inside the chamber is adjusted to the pressure in the skirt (in the airtight space below the bottom plate) to open the inner door, or to the external pressure (atmospheric pressure). By lowering and opening the outer door, necessary equipment (for example, a stand, an air bag, etc.) can be taken in and out while keeping the pressure in the skirt constant. Also, a part of the air chamber type passage 15 is provided with a pipe that leads to the inside of the skirt 11, and the air pressurized by the blower 16 can be supplied to the inside of the skirt 11 through this pipe. Yes. This pressure is set to a pressure that can support the bottom plate with pressurized air, for example, about 100 mmAq when the bottom plate is 1 cm thick. With this configuration, it is possible to support the bottom plate 3 with pressurized air by supplying relatively low-pressure pressurized air from the blower 16 into the skirt 11. In addition, since the pressurizing pressure is very low, workers can freely enter and exit the interior without impairing work efficiency.
[0017]
Furthermore, in step 3 of FIG. 1C, it is preferable to replace the entire gantry 2 with the air bag 12 through the air chamber type passage 15 after the supply of pressurized air. Next, after removing the gantry, the entire air bag 12 is removed via the air chamber type passage 15. As a result, when removing the gantry (in this case, the air bag), the air bag 12 can be pulled out by pulling out the air in the air bag 12 from the air chamber type passage 15 without the person under the bottom plate 3. 12 can be removed efficiently and easily.
[0018]
Further, as shown in FIG. 1B, it is preferable to install a weight 18 on the bottom plate 3 before supplying pressurized air, thereby preventing the bottom plate 3 from swelling. The weight 18 may be an iron plate or the like, but is preferably a hollow container that can be filled with water and has a flat bottom surface. By using such a hollow container, installation and removal of weights can be further facilitated.
[0019]
In steps 4 and 5 of FIG. 1 (D), the pressure is adjusted so as to support the bottom plate 3 with only pressurized air, and then the pressure is gradually reduced by removing the pressurized air, so that the bottom plate 3 is placed on the cold insulation material 1. Lowering and installing the bottom plate 3 at the pre-marked position completes the installation of the bottom plate of the cryogenic tank according to the present invention.
Of course, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.
[0020]
【The invention's effect】
According to the above-described method of the present invention, it is necessary to attach a fixing piece around the bottom plate when setting a flexible sheet material (skirt), but the number required is smaller than that of a conventional hanging bracket. In addition, the work can be easily and efficiently performed on the ground, and it is possible to eliminate conventional work such as temporary attachment / removal of hanging metal fittings and setting of wires, and inefficient work. Also, laying, welding, and inspection of the bottom plate are exactly the same as before, and the conventional cold insulation material can be used as it is to keep the cold insulation performance at the bottom of the bottom plate high, and work can be done using the conventional stand as it is. Efficiency can be performed efficiently. Furthermore, there is almost no restriction on the shape of the bottom plate except that it is necessary to attach a flexible sheet around the bottom plate. Further, although an air chamber type passage is required as a device, since the pressurized air acts on the entire lower surface of the bottom plate, the pressure of the pressurized air is very low, and a simple double door air chamber type passage is sufficient.
[Brief description of the drawings]
FIG. 1 is a schematic view of a method for installing a bottom plate of a cryogenic tank according to the present invention.
FIG. 2 is a perspective view of an airbag.
FIG. 3 is an enlarged view of a part A in FIG.
FIG. 4 is a schematic plan view of FIG.
FIG. 5 is a view showing a conventional method for installing a bottom plate of a low-temperature tank.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cold insulating material 2 Base 3 Bottom plate 4 Hanging metal fitting 5 Wire 7 Annular plate 11 Flexible sheet material (skirt)
11a Air hose 12 Air bag 12a Drawer rope 12b Pressurizing air hose 13 Fixing piece 15 Air chamber type passage 16 Blower 18 Weight

Claims (3)

In the method of installing the bottom plate of the low temperature tank, laying the cold insulation material on the bottom, placing a plurality of mounts for assembling the bottom plate on the cold insulation material, laying and welding the steel plates for the bottom plate on the mount, and inspecting the welded parts,
Between the periphery of the bottom plate and the bottom surface is hermetically connected by a flexible sheet material to form an airtight space below the bottom plate,
Install weights on the bottom plate,
Thereafter, pressurized air is supplied to the airtight space through the flexible sheet material, and the bottom plate is supported by the pressurized air,
Through the air chamber type passage provided in the flexible sheet, the base is removed, and the bottom plate is supported only by pressurized air,
Next, it is a method of removing the pressurized air and installing the bottom plate on the cold insulation material.
A method of installing a bottom plate of a low-temperature tank , wherein the weight is placed on the bottom plate before the pressurized air is supplied to prevent the bottom plate from swelling . The method of claim 1 , wherein the weight is a hollow container that can be filled with water and has a flat bottom surface. Before the formation of the airtight space, the part of the frame is extendable vertically by the internal pressure to replace the air bag drawer rope is attached,
After the supply of pressurized air, the entire base is replaced with the air bag through the air chamber type passage,
2. The method of installing a low temperature tank bottom plate according to claim 1 , wherein the air bag is removed by pulling the pull-out rope through the air chamber type passage after the gantry is removed .

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