JPH0337498A - Installation method for bottom plate of inner shell for double shell tank - Google Patents

Abstract

PURPOSE:To install a bottom plate with no working machine used by providing a plurality of columnar supports in the inner bottom section of the inner container of a double shell tank, arranging a plurality of bottom members on the upper surfaces of said supports so as to be welded, thereby filling an insulating cold reserving material among said bottom members and a foundation. CONSTITUTION:The bottom plate 16 of an outer container is installed on a tank foundation 15, an outer container 2 and a roof 2b are formed, and an inner container 3 and a roof 3b are also formed in sequence. Within the inner side of a cold reseving layer 5, columnar supports 18 each height of which is equivalent to that of each support, are provided. A plurality of bottom members are placed over the columnar supports 18, and the peripheral section of them are welded so as to be joined so that a sheet of a bottom plate 17 is formed. After inspection for welding has been over, an insulating cold reseving material is blown in to gaps among the columnar supports 18 at a work site so as to be filled in. By this constitution, the bottom plate of the inner container is safely installed in a short time while complicated and dangerous works using scaffoldings and ropes are eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in the installation method of the inner tank bottom plate of a double shell tank.

[Prior Art] Conventionally, the bottom plate of the inner tank of a double-shell tank for storing liquefied gas such as LNG is formed after an inner tank is formed inside an outer tank constructed on a foundation.

That is, as shown in FIG. 4, a cold insulation layer 5 of pearlite concrete or the like is formed inside the outer tank 2, and the inner tank 3 is formed on the Ayuku plate 4 above this. Then, a heat insulating member such as foam glass is piled up inside the cold insulation layer 5 up to the installation position of the bottom plate 7 to form a bottom plate foundation 9. After this, the surface of this bottom plate foundation 9 is reinforced with plywood board 8 or the like, and a bidet-type scaffold l○ is erected on top of this. A large number of bottom plate members 7a forming the bottom plate 7 are placed on this scaffold 10, and these are welded to assemble one bottom plate 7.

After completing this assembly, after inspecting the welded part on the back side of the bottom plate 7, the bottom plate 7 is lifted up with a number of ropes 11 hanging from the side wall of the inner tank 3, the scaffold 10 is removed, and the bottom plate 7 is
While maintaining the horizontal level, hang it down again with the rope 11,
It was installed on the bottom plate foundation 9.

[Problems to be Solved by the Invention] However, although the method for installing the bottom plate described above has the advantage of being able to inspect not only the front surface of the assembled bottom plate 7 but also the weldability of the back surface, It is necessary to assemble and remove the base plate 7 on the base plate 9, and a complicated process of lifting and lowering the base plate 7 with the lobes 11 is required, which also poses a safety problem.

This hindered the efficiency of tank construction work, and there was a need to improve the method of installing the bottom plate.

The present invention has been made in response to the above-mentioned request, and it is possible to remove the bottom plate of the tank without requiring complicated work using equipment such as scaffolding or ropes, that is, by omitting the work of lifting and lowering the bottom plate 7. The purpose is to provide a method for installing a bottom plate that can be installed safely and quickly.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a method for installing an inner tank bottom plate after forming an inner tank and an outer tank on an installation foundation of a double shell tank. Inside the tank, after installing a plurality of columnar supports having a predetermined strength and heat insulation property at appropriate intervals so that the upper surface thereof is flush with the installation surface of the inner tank bottom plate, the upper surface of these columnar supports is installed. A plurality of bottom plate members are arranged and welded to assemble the inner tank bottom plate, and then a heat insulating and cold insulating material is filled between the inner tank bottom plate and the stationary foundation.

[Operation] After forming the outer tank and its bottom plate on the installation foundation of the double shell tank, an inner tank is constructed by forming a cold insulation layer inside the outer tank to support the inner tank. Inside this cold insulating layer, a large number of columnar supports having strength and heat insulation are provided upright at appropriate intervals. The top surface of this columnar support should be flush with the surface on which the bottom plate is installed. Then, a plurality of bottom plate members forming a bottom plate are arranged on the upper surface of this columnar support, and these members are assembled as a bottom plate by welding. Thereafter, the gap between the columnar supports is filled with a cold insulating material to form the bottom plate of the double-shell tank inner tank.

This makes it possible to install the bottom plate of a double-shelled tank, which has cold insulation and strength, in a simple work and in a short time without using assembly equipment such as scaffolding or hanging members. can.

[Example] A preferred embodiment of the present invention will be described based on the drawings.

First, as shown in FIG. 1, a tank foundation 15 is constructed, and an outer tank bottom plate 16 is laid on top of it.

On this outer tank bottom plate 16, a plurality of outer tank measurement plates are sequentially stacked from the bottom and joined together by welding to form an outer tank 2.
The upper opening is covered with the roof 2b. Next, a cold insulation layer 5 is formed using pearlite concrete or the like on the outer tank bottom plate 16 along the inside of the outer tank 2, and an annular plate 4 provided on the cold insulation layer 5 is installed. Then, the outer tank roof 2b is attached with the inner tank roof 3b suspended using the air rising method. The inner tank 3 is formed by sequentially stacking and welding a plurality of inner tank measuring plates from the bottom at appropriate intervals from the inner wall of the outer tank 2. This inner tank 3 is made of a low-temperature material that can handle the liquefied gas to be stored, such as low-temperature high-toughness steel such as 9% nickel steel.

Next, the installation of the inner tank bottom plate 17, which is a feature of this embodiment, will be explained.

Inside the cold insulation layer 5 at the bottom of the inner tank 3, there is installed a columnar support 18 with a height corresponding to the height of the cold insulation layer 5 and whose top or bottom plate 17 is installed flush with the surface. Set up standing up.

This columnar support 18 is made of a polycarbonate material, which is a well-known reinforced plastic that has strength and heat insulation properties that can support the weight of the bottom plate 17, and is shaped as a prismatic body of appropriate dimensions, but is not limited to a prismatic body, and may also be of a cylindrical shape or the like. But that's fine.

As shown in FIG. 2, the columnar supports 18 are arranged in a plurality of rows concentrically around the center of the bottom plate 17.

Note that this arrangement is not limited to concentric circles, but may be arranged, for example, in a grid pattern. Since the columnar supports 18 are arranged in this manner, the flatness of the bottom plate 17 can be maintained without attaching reinforcing members or the like to the bottom plate 17.

Next, a large number of bottom plate members 17a forming the bottom plate 17 are placed on the upper surface of the columnar support 18, as shown in FIG. These bottom plate members 17a are placed with appropriate overlapped portions formed in order to join their peripheral edges by overlap welding.
One bottom plate 17 is formed by welding the bottom plate members 1.7a together. This joining is limited to lap welding, butt welding may also be used.

During this welding, the peripheral edge of the bottom plate 17 is supported by a plurality of hanging wires 19 from which the four walls of the inner tank 3 are suspended.

After forming the bottom plate 17, the upper and lower surfaces of the weld line of the bottom plate 17 are inspected using a suitable inspection means. Top surface inspection can be easily performed since the top is open. Further, in the case of underside inspection, if necessary, part of the columnar support 18 is removed to form a gap so that an inspector can easily conduct the inspection through this gap. Further, the removal of a part of the columnar monkey 1-18 is also carried out when the weld line is located on two sides of the support 18, and the weld line is inspected.

This bottom plate 17 is also made of low-temperature, high-toughness steel, such as 9% nickel steel, like the inner tank 3.

After that, the columnar support 18 supporting the bottom plate 17
Hard urethane foam (JIS
A heat insulating and cold insulating material 20 made of A9514 (equivalent to A9514) is blown and filled by on-site foaming work. Even in this case, necessary columnar supports 18 may be removed to facilitate the work.

Thereafter, the peripheral edge of the formed bottom plate 17 and the lower annular plate 4 of the inner tank 3 are joined by welding, and the hanging wire 1
9 is removed to complete the installation of the bottom plate 17.

In this embodiment, the bottom plate 17 of the inner tank 3 is installed in this manner, so there is no need to attach and remove scaffolding or perform complicated wire operations as in the conventional case.

[Effects of the Invention] As described above, according to the present invention, the inner tank bottom plate of a double-shell tank can be installed safely and in a short time by a simple method without using any other equipment.

[Brief explanation of drawings]

Fig. 1 is an explanatory cross-sectional view of a double-shelled tank with a bottom plate installed by an embodiment method according to the present invention, Fig. 2 is a view from the FIG. 4 is a cross-sectional view illustrating a conventional method for installing a bottom plate. In the figure, 3 is an inner tank, 17 is a bottom plate of the inner tank, 17a is a bottom plate member, 18 is a columnar support, and 20 is a heat insulating cold insulating material.

Claims (1)

[Claims] 1. In the method of forming the inner and outer tanks on the tank foundation of a double shell tank and then installing the inner tank bottom plate, the inner bottom of the formed inner tank is installed so that its top surface is the same as the installation surface of the inner tank bottom plate. After providing a plurality of columnar supports having a predetermined strength and heat insulation properties at appropriate intervals, a plurality of bottom plate members are arranged on the upper surface of these columnar supports, and these are welded to form the inner tank bottom plate. 1. A method for installing an inner tank bottom plate of a double shell tank, the method comprising: assembling the inner tank bottom plate as a double shell tank, and then filling a heat insulating cold insulating material between the inner tank bottom plate and the outer tank bottom plate.