JPS6354859B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a method for constructing a multi-shell tank for storing low-temperature liquefied gas, and in particular, a multi-shell tank that ensures safety during storage of actual liquid after completion. Concerning tank construction methods.

[Prior Art] Most of the low-temperature tanks currently in use have a double-shell structure, and triple- or multi-shell tanks have not been realized in practice even though theoretical structures have been developed or provided. Not implemented. This is thought to be due to the fact that a construction method that can ensure safety after the tank is completed has not been found.

Generally, when constructing a double-shell tank, the inner tank is assembled after the outer tank, so as shown in Figure 1, after the outer tank 1 is assembled, the lower side plate is used to carry the inner tank materials, etc. After opening the construction opening 2 and introducing materials such as the cold insulation material for the foundation and the bottom plate and side plates of the inner tank into the outer tank 1 through the construction opening 2 to form a cold insulation layer 3 at the inner bottom of the outer tank 1, The inner tank bottom plate 4a is laid on this cold insulation layer 3, and then the inner tank side plates 4b are stacked. Moreover, the roof 6a of the inner tank 4 is the bottom plate 4a.
After the above assembly, it is suspended inside the roof 6 of the outer tank 1 and attached to the upper edge of the stacked side plates 4b. In addition, even in the process of assembling or attaching the side plate 4b and roof 6a of the inner tank 4, the inner tank side work opening 5 is opened in the inner tank side plate 4b facing the above-mentioned outer tank side work opening 2. After assembling the inner tank 4 in the outer tank 1, each construction opening 2, 5 is closed and the inner tank 4 is subjected to a pressure test (water test).

[Problems to be Solved by the Invention] However, applying this double-shell tank construction method to a triple-shell tank poses a major problem in terms of integrity, which is the most important point when storing actual liquid in a complete tank. It is impossible because it occurs.

That is, when constructing a triple shell tank using the above method, after constructing the double shell tank shown in FIG. 1 as described above and carrying out a pressure test on the inner tank 4,
Since the actual liquid storage tank 7 must be assembled as shown by the dashed line in the same figure, in order to incorporate materials such as the actual liquid storage tank 7 and the concrete foundation 8, the inside and outside of the double-shelled tank after the pressure test are prepared. Construction ports 5 and 2 must be opened again in both tanks 4 and 1.

Although opening the construction openings 5 and 2 near the lower corners of the inner and outer tanks 4 and 1, which are the parts with the highest stress in a double-shell tank after a pressure test, is itself a big problem. Due to the presence of the actual liquid storage tank 7, it is impossible to close the construction openings 5 and 2 and subject the inner tank 4 of the double shell tank to a pressure resistance test again after the actual liquid storage tank 7 is assembled.

Therefore, if the construction method of a double-shell tank is applied to a triple-shell tank, the maximum stress near the bottom corner of the double-shell tank cannot be ensured, which greatly impedes safety, which is the most important aspect of this type of tank. .

[Means for Solving the Problems] This invention has been made in view of the above circumstances, and its purpose is to easily form a multi-shell tank with three or more shells,
It is an object of the present invention to provide a new method for constructing a multi-shell tank that can greatly contribute to improving its safety.

In order to achieve the above object, the present invention forms an outer tank having a double shell or more, tests the innermost shell for pressure resistance, and then opens a construction opening in the roof of the outer tank and extends the outer tank from the construction opening. Inner tank material is carried into the inner shell to form an inner tank for storing actual liquid, and the construction opening is then sealed.

[Function] With the above configuration, after a pressure test is performed on the innermost shell of the outer tank, a construction opening is opened in the roof of the outer tank, and while the inner tank material is brought in through this construction opening, the inner tank for storing actual liquid is constructed. A multi-shell tank is constructed by forming a tank and then closing the construction opening. Therefore, since there is no need to form a construction opening in the side plate of the outer tank, a multi-shell tank with three or more shells can be constructed without impairing the maximum stress near the inner bottom corner of the outer tank.

[Example] Below, a preferred example when the method of the present invention is applied to a triple shell tank will be described based on FIGS. 2 to 5. First, once the tank foundation 10 shown in FIG. 2 is constructed and the outer shell bottom plate 11 of the outer tank is laid on top of it, a plurality of outer shell side plates are formed into blocks on the peripheral edge of the outer shell bottom plate 11. 12 ₁ to 12 _o are sequentially stacked and joined (welded) starting from the bottom. Also,
After the bottomed cylindrical outer shell 12 is assembled and formed from room-temperature materials, its upper end opening is covered with a roof 13. Next, after forming the cold insulation layer 14 on the bottom plate 11 of the outer shell 12, the inner shell bottom plate 1 as an outer tank is placed on top of the cold insulation layer 14.
5, and a plurality of inner shell side plates 16 ₁ to 16 _o , which are formed into blocks on the upper peripheral edge side of the bottom plate, are attached to the outer shell 12.
By forming a predetermined gap between the side plates 12 ₁ to 12 _o of the inner shell 1
6 is assembled and formed, and the upper end opening of this inner shell 16 is covered and sealed with a roof 13a. In this case, the inner shell bottom plate 15 and the inner shell side plates 16 ₁ to 16 _o are made of a material with high low temperature toughness, such as 9% nickel steel, which can handle the stored liquid.

As described above, the structure is composed of the outer shell 12 and the inner shell 16, and the upper end openings from the outer shell 12 and the inner shell 16 are connected to the roofs 13 and 1.
Since the outer tank 17 having a double shell structure covered with the outer shell 3a is formed, the inner shell 16 is subjected to a pressure test after its formation.

After this pressure test, as shown in FIGS. 3 and 5, a trolley rail 18 for assembling the inner tank is attached to the lower surface of the roof 13a of the inner shell 16 of the outer tank.
A plurality of interlocking trolley hoists 19 are suspended from this rail, and a construction opening 2 for carrying in inner tank material is provided in a part of the roofs 13 and 13a, which communicate with each other.
Open 0.

After pouring a concrete foundation 21 for the inner tank on the bottom plate 15 of the inner shell 16 of the outer tank 17, the annular plate 22 is lifted by a crane 23 shown in FIG. 2
0 into the inner shell 16 as the innermost shell of the outer tank 17 and assembled on the concrete foundation 21 at the inner bottom thereof.

Next, the plurality of side plates 24 ₁ to 24 _o for the inner tank, which have been made into blocks on the ground in advance, are hung by the crane 23 in the same way as the above-mentioned annular plate 22 and inserted into the inner shell 16 of the outer tank from the construction opening 20. The items will be brought in sequentially.

The side plates 24 ₁ to 24 _o that have been carried in are sequentially suspended by the trolley hoist 19, and sequentially stacked and joined (welded) on the above-mentioned annual plate 22. In this case, each of the side plates 24 ₁ to 24 _o is stacked with appropriate gaps between them and the side plates 16 ₁ to 16 _o of the inner shell 16 of the outer tank.

After all the side plates 24 ₁ to 24 _o have been assembled in this way, the plurality of inner tank bottom plates 25 are inserted into the inner shell 16 of the outer tank and placed on the concrete foundation 21 in the same manner as for the side plates. Lay down.

With the above steps, a bottomed cylindrical inner tank 26 for storing actual liquid with an open upper end is formed within the inner shell 16 of the outer tank. The side plate 24 ₁ of the inner tank 26 for storing the actual liquid
24 _o , bottom plate 25, and annual plate 2
As with the case of the inner shell 16 of the outer tank, a material with high low-temperature toughness is used for each of the inner shells 2 and 2.

Next, the inner tank 26 for storing the actual liquid is subjected to a pressure test (hydraulic test), and after the test, the roof 13,
The construction opening 20 of 13a is sealed.

Thereafter, an airtightness test is performed by applying gas pressure or the like to each of the outer shell 12 and inner shell 16 of the outer tank 17.

With the above, the triple-shell tank is completed, and when it is used, liquefied gas such as LPG, LNG, etc. is stored in the inner tank 26 for storing actual liquid, which has an open top end inside the inner shell 16 of the outer tank. Cold liquid will be stored. The inner shell 16 of the outer tank is exposed to the atmosphere due to the stored liquid, and even if the low temperature stored liquid overflows from the inner tank 26 due to the sloshing phenomenon caused by an earthquake, the inner shell 16 of the outer tank will not undergo rapid thermal contraction. It performs the role of a complete liquid barrier without causing any damage.

In addition, in the above embodiment, the roofs 13, 13a
The annular plate 22 and inner tank side plate 24 ₁ taken into the inner shell 16 of the outer tank from the construction opening 20 of
The means for assembling each of the bottom plate ₂₄ and the bottom plate 25 does not necessarily rely on the trolley hoist 19.
Further, the outer tank 17 having a double shell structure may be formed by any conventional method, and the outer tank 17 may be formed by any conventional method.
may have a double-shell or more multi-shell structure.

The effects of the above embodiments include the following.

(1) When constructing a tank with a triple shell or more, the stress of the innermost shell obtained by pressure testing the innermost shell of an outer tank formed with a double shell or more structure,
In particular, the maximum stress near the bottom corner of the innermost shell can be maintained as it is, and the maximum stress near the bottom corner of the innermost shell once subjected to a pressure test is due to the material intake when assembling the inner tank for storing actual liquid. There will be no possibility of any loss.

(2) Therefore, after assembling the inner tank for storing actual liquid, a pressure test can be performed only on the inner tank, regardless of the outer tank.

(3) In addition, the airtightness of the multi-shell tank can be ensured when the multi-shell tank is completed by performing an airtightness test by sealing the opening in the roof mentioned above for the pressure resistance test of the inner tank.

[Effects of the Invention] As described above, according to the present invention, it is possible to easily form a multi-shell tank having three or more shells, and to improve its safety.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a double-shell tank illustrated to explain the conventional method, and FIGS. 2 to 4 are multi-shell tanks illustrated according to the assembly order to explain a preferred embodiment of the method of the present invention. A sectional view of the tank, and FIG. 5 is a partially enlarged perspective view of the tank when assembled. In the figure, 12 is the outer shell, 13, 1 is the roof, 16 is the inner shell, 17 is the outer tank, 20 is the roof construction opening, 24 ₁ -
24 _o and 25 are side plates and a bottom plate as inner tank forming members, and 26 is an inner tank for storing actual liquid.

Claims (1)

[Claims] 1. After forming an outer tank with a double shell or more and subjecting its innermost shell to a pressure resistance test, a construction opening is opened in the roof of the outer tank, and the inner tank material is brought into the innermost shell through the construction opening. 1. A method for constructing a multi-shell tank, characterized in that an inner tank for storing actual liquid is formed, and the construction opening is then sealed.