JP2006143291A - Floating roof type storage tank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a floating roof type storage tank which ensures the buoyancy of a floating roof and prevents such a trouble as collapsing of the floating roof even if a sloshing of magnitude occurs. <P>SOLUTION: The floating roof type storage tank comprises a tank body which stored a liquid, and the floating roof 120 which is placed in the tank body and has a pontoon 3 on the outer periphery of the floating roof 120, the pontoon 3 floating on the liquid stored in the tank body. The pontoon 3 contains one or two floats 6 consisting of a bag-like member 62 holding a gas 61 sealed therein. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a floating roof type storage tank used for storage of petroleum products such as crude oil, gasoline, naphtha and the like, and in particular, even when the floating roof is partially damaged by an external force such as an earthquake. The present invention relates to a floating roof type storage tank that can reliably prevent settlement.

In general, a floating roof type storage tank is known as a tank (storage tank) for storing a large amount of liquid such as oil.
The floating roof type storage tank has a cylindrical tank body that opens to the top without a roof as a storage tank, and has a structure in which a thin steel plate called floating roof is floated on the surface of oil stored in this tank body. ing.
Such a floating roof type storage tank can store and store oil and the like in a good condition without requiring a roof of the tank body, and can be installed at a lower cost than a dome type covered tank, etc. Widely used as large-capacity oil tanks.

FIG. 5: has shown schematic sectional drawing of the common floating roof type | mold storage tank concerning a prior art example.
Moreover, FIG. 6 has shown the general | schematic expanded sectional view of the principal part in the floating roof of the floating roof type storage tank concerning a prior art example.
As shown in FIGS. 5 and 6, the floating roof type storage tank 1 includes a cylindrical tank body 110 having an upper opening, and a floating roof 120 floated on a liquid surface of oil or the like stored and stored in the tank body 110. I have.

The floating roof 120 is made of a thin steel plate or the like formed in a disk shape corresponding to the tank shape, and is provided with a pontoon 3 including dozens of hollow floating chambers 30 connected in an annular shape along the outer peripheral edge. The pontoon 3 (floating chamber 30) floats on the liquid surface such as oil.
That is, the floating roof 2 moves up and down as the liquid level rises and falls, and has a structure in which no gap is always generated between the liquid level and the floating roof 120. The reason is that if there is a gap between the liquid level of oil or the like in the tank and the floating roof, the vaporized volatile gas stays and there is a risk of explosion or the like.

The pontoon 3 includes an outer rim plate 31, an inner rim plate 32, a pontoon lid plate 33 and a pontoon bottom plate 34, and each floating chamber 30 is partitioned by a partition plate 35. A manhole 36 is provided in the pontoon cover plate 33 of each floating chamber 30 so that an operator can enter the pontoon cover plate 33 for inspection or the like.
A deck 122 is laid inside the pontoon 3 via a compression ring 121.
Between the outer peripheral edge of the pontoon 3 and the side wall 111 of the tank body 1, a sealing device 4 is arranged in an annular shape so that the inside of the tank is shut off and sealed from the outside, and the stored liquid is vaporized and discharged into the tank. Intrusion of rainwater is prevented.

  The floating roof 120 is held by a guide pole 5 that penetrates the pontoon 3 so as not to move or rotate in the tank. The guide ball 5 is a columnar member fixed to the side wall 111 of the tank main body 110, and prevents the floating roof 120 from rotating and moving by penetrating the pontoon 3. Although not shown, the pontoon 3 through which the guide pole 5 penetrates is provided with a steel pipe, functions as a bearing for the guide pole 5, and maintains the airtightness of the pontoon 3.

By the way, in the various tanks (tanks) that contain and store a large amount of liquid, such as the floating roof type storage tank 1 as described above, the liquid contained (external force and vibration force applied to the tank) It is known that so-called sloshing (liquid level fluctuation) occurs in which the internal fluid) fluctuates.
For example, in a large tank such as an oil tank, sloshing with a large amplitude may be caused by an external force such as an earthquake. When such sloshing occurs, the tank is damaged or the stored liquid overflows, Oil etc. may leak outside.
For this reason, according to the Japanese Fire Service Act, even if two adjacent floating chambers 30 of the pontoon 3 divided into several tens of locations and parts other than the floating chamber 30 are damaged, the floating roof 120 may not sink. It is requested. And by design, even if the two adjacent floating chambers 30 lose buoyancy, the volume and section of the pontoon 3 are considered so that the floating roof 120 does not sink as a whole.

As a technique for adding buoyancy to the floating roof, for example, a plurality of hollow tubes are arranged on the deck, and a hollow elastic bag is inserted into the bottom surface of the deck through the hollow tube at the time of repair. There is a technique of a deck repairing method for a lower floating roof type storage tank that supplies compressed gas via a wall and expands it (Patent Document 1).
According to this technique, even when a relatively large penetration portion is generated, the outflow is prevented and the penetration portion of the deck can be repaired safely without stopping the use of the floating roof storage tank. However, the above-described technique allows repair by adding buoyancy to the floating roof and lowering the draft to the bottom of the deck, and cannot solve the problem of the present invention.
JP 10-316193 A

However, when a long-period earthquake that coincides with the natural frequency of the floating roof 120 occurs, for example, the floating roof storage tank 1 has two or more floating chambers of the pontoon 3 due to sloshing larger than previously expected levels. When 30 is broken and the buoyancy is lost, there is a problem that the floating roof 120 may sink.
Even if the liquid does not enter the inside of the pontoon 3 (floating chamber 30) from below, the liquid overflows to the upper part of the floating roof 120 due to the inclination of the floating roof 120, and this liquid enters the inside of the pontoon 3. There is a problem that it is assumed that the pontoon 3 loses buoyancy due to intrusion from above (for example, the manhole 36).

  The present invention has been proposed in order to solve the above problem, and even if a larger sloshing occurs and the pontoon breaks and liquid enters the inside, the buoyancy of the floating roof is reliably ensured, and the floating roof An object of the present invention is to provide a floating roof type storage tank that can prevent problems such as sinking.

In order to achieve the above object, a floating roof type storage tank according to the present invention includes a tank body for storing a liquid, and a pontoon that is housed in the tank body and floats on the liquid stored in the tank body. In the floating roof type storage tank provided with the floating roof, the inside of the pontoon and / or the lower part of the floating roof is provided with one or more floats.
In this way, even if the pontoon is damaged due to sloshing or the like exceeding the conventional prediction and the buoyancy of two or more floating chambers is lost, the problem that the floating roof sinks due to the floating buoyancy is ensured. Can be prevented.

In the floating roof type storage tank of the present invention, the float is sealed with a float of a bag-like member sealed with gas, a float of a lightweight member having a gap, and / or a light weight having a gap. The structure is a floating member.
In this way, unlike the conventional pontoon made of steel plate, the float of the present invention does not break even when an external force such as an earthquake acts on it, so it generates buoyancy even under conditions of greater sloshing. Can be made.

Moreover, the floating roof type storage tank of the present invention is configured such that the material of the bag-shaped member is a composite material having a base material made of rubber or resin and a reinforcing material.
If it does in this way, the mechanical strength of the base material which consists of rubber | gum or resin can be improved, and it can respond also to bigger impacts, such as an earthquake.

In the floating roof type storage tank of the present invention, the bag-like member includes a stopper that encloses or exhausts gas.
If it does in this way, a bag-like member can be easily installed in an existing pontoon via a manhole, and also a bag-like member can be easily removed in the case of inspection.

Moreover, the floating roof type storage tank of this invention is set as the structure by which compressed gas is supplied to the said bag-shaped member.
If it does in this way, gas can be easily supplied to a bag-shaped member and workability | operativity can be improved.

Moreover, the floating roof type storage tank of the present invention has a configuration in which a plurality of plugs of the bag-like members are connected by piping, and a valve is provided for each bag-like member.
If it does in this way, gas can be efficiently enclosed or exhausted to a plurality of bag-like members via piping by which a valve was opened. Also, if the valve is closed after the gas is sealed in a plurality of bag-shaped members, the gas is sealed for each bag-shaped member, so that even if one float breaks and loses buoyancy, the remaining float is buoyant Can be maintained.

Moreover, the floating roof type storage tank of this invention is set as the structure which used the said lightweight member as the foaming material.
In this case, buoyancy is generated by the fine gaps included in the foamed material, so that the reliability of floating can be improved.

Further, the floating roof type storage tank of the present invention is provided with a float made of a plurality of bag-like members inside the pontoon, and a plug for sealing or exhausting the gas provided in the bag-like member, The configuration is arranged around the inspection port of the pontoon.
In this way, multiple floats are installed in each floating chamber, and the floats are miniaturized. Therefore, obstacles such as reinforcing ribs can be avoided, improving transport efficiency and workability, and dispersing buoyancy. Safety can be improved. Moreover, by disposing the stopper of the bag-like member around the inspection port (manhole), the bag-like member can be easily installed in the pontoon, and the workability can be further improved.

Moreover, the floating roof type storage tank of the present invention has a configuration in which the floats are connected.
If it does in this way, even if it is a case where big sloshing has generate | occur | produced on the floating roof, the installation stability of a floating can be improved.

As described above, according to the floating roof type storage tank of the present invention, even if the pontoon is damaged by sloshing or the like and the buoyancy of two or more floating chambers is lost, unlike a steel pontoon, Due to the floating buoyancy that does not break even when an external force such as an earthquake acts, it is possible to reliably prevent a problem that the floating roof sinks.
Therefore, the safety of the floating roof storage tank against disasters such as earthquakes can be improved.

  Hereinafter, preferred embodiments of a floating roof type storage tank according to the present invention will be described with reference to the drawings.

[First embodiment]
First, with reference to FIG. 1, a floating roof storage tank in which a float made of a bag-like member sealed with gas is disposed inside a pontoon will be described.
FIG. 1: has shown schematic sectional drawing of the floating roof of the floating roof type storage tank which concerns on 1st embodiment of this invention.
In the figure, a floating roof type storage tank (not shown) is a floating roof type storage tank for storing and storing a large amount of oil, and has a floating 6 inside each floating chamber 30 of the pontoon 3. Except for this, the construction is almost the same as that of a conventional general floating roof storage tank 1 (see FIG. 6).
Therefore, in FIG. 1, the same components as those in FIG. 6 are denoted by the same reference numerals, and detailed description thereof is omitted.

Specifically, the floating roof type storage tank shown in FIG. 1 includes a float 6 made of a bag-like member 62 in which a gas 61 is sealed in each floating chamber 30.
The float 6 is an airtight bag having a shape substantially corresponding to the internal shape of each floating chamber 30 of the pontoon 3 in a state where the gas 61 is sealed, and the gas 61 is sealed or exhausted below the manhole 36. The structure is provided with a stopper 63.

Here, since the float 6 is provided with the plug 63, the bag-like member 62 that has been evacuated and deflated can be carried into the existing pontoon 3 from the manhole 36, and the gas 61 is passed through the plug 63. By enclosing, the float 6 can be easily installed. Further, when inspecting the pontoon 3, the gas 61 sealed through the plug 63 is exhausted, and the squeezed bag-like member 62 can be easily carried out of the pontoon 3.
That is, since the float 6 can be easily attached to the existing pontoon 3, there is no cost for remodeling the floating roof storage tank 1, and it is extremely economical. Moreover, since it can be attached to the floating roof storage tank 1 in operation, for example, the operation of extracting the stored liquid does not occur, and it can be attached easily and in a short period of time.

  Further, when the float 6 is installed inside the floating chamber 30, it is preferable that the exhausted bag-like member 62 is laid on the pontoon bottom plate 34 and then the gas 61 is gradually sealed. Since the swollen state of the shaped member 62 can be visually confirmed, the reliability of the installation work can be greatly improved.

Preferably, when the gas 61 is sealed in the bag-like member 62, the compressed gas may be supplied. In this way, the gas 61 can be easily supplied to the bag-like member 62, thereby improving workability. be able to. The main purpose of using the compressed gas is to improve workability when the gas 61 is sealed in the large bag-like member 62, and the sealed gas 61 is sealed at substantially the same pressure as the atmospheric pressure. The
In consideration of safety such as explosion prevention, an inert gas such as nitrogen gas can be used as the gas 61 to be sealed. However, air is used from the viewpoint of preventing an operator from lacking oxygen during sealing or exhausting. Can also be used.

  Usually, the material of the bag-like member 62 is a rubber sheet with a reinforcing cloth, which is also used as a sealing material for the floating roof storage tank 1. As the rubber material, NBR (acrylonitrile butadiene rubber) or the like is used in consideration of oil resistance and wear resistance. Thus, maintenance-free for the float 6 can be realized by using a material excellent in oil resistance and wear resistance. In addition, when the liquid stored in the floating roof storage tank 1 is a flammable substance such as petroleum, it is necessary to use a material that does not generate a spark due to collision with metal or sliding, such as NBR. This is extremely important for the safety of the storage tank 1. Further, since the bag-like member 62 has flexibility, it can follow the deformation of the floating chamber 30, and even when the floating chamber 30 is deformed by sloshing, as long as the bag-like member 62 is not broken, Can generate buoyancy.

Further, by using a reinforcing cloth made of glass fiber or the like as the reinforcing material, the mechanical strength of the base material made of rubber can be improved, and it is possible to cope with a larger impact such as an earthquake.
The bag-like member 62 is not limited to the above materials, but is a material that satisfies non-ignition properties due to collision / sliding with metal, mechanical strength, flexibility, oil resistance, and wear resistance. For example, a resin such as nylon may be used instead of rubber.

Since the float 6 is installed inside the floating chamber 30 of the pontoon 3, in a normal state in which the pontoon 3 is not damaged, it does not come into contact with oil (liquid), and therefore, degradation caused by contact with oil for a long time. Therefore, durability can be improved.
Furthermore, in a normal state where the pontoon 3 is not damaged, only atmospheric pressure acts on the bag-like member 62, and the external pressure from the liquid and the weight of the floating roof 3 do not act. From the viewpoint of, it is excellent in durability. Further, since the amount of mechanical strength that decreases with time in the design stage is reduced, the thickness of the bag-like member 62 can be reduced, and the manufacturing cost can be reduced.

  Thus, according to the floating roof type storage tank according to the present embodiment, for example, a long-period earthquake that matches the natural frequency of the floating roof 120 occurs, and the floating chamber 30 of the pontoon 3 is caused by a large sloshing. When the liquid breaks into the pontoon 3 (floating chamber 30) and the buoyancy caused by the floating chamber 30 is lost, the buoyancy 6 is generated with the same buoyancy as the lost buoyancy. Problems such as sinking can be reliably prevented. In addition, it is assumed that the liquid overflows to the upper part of the floating roof 120 due to the inclination of the floating roof 120, the liquid enters the inside of the pontoon 3 from above (for example, the manhole 36), and the pontoon 3 loses buoyancy. However, since the floating 6 exists in the floating chamber 30, almost no liquid can enter the inside of the pontoon 3 (floating chamber 30).

In addition, by providing the float 6 in the floating chamber 30 so that it can be carried in and out, the float 6 can be installed quickly and easily without remodeling the existing floating roof storage tank 1. Can be economically effective.
In addition, the floating roof type storage tank, which is a huge structure, has been studied in detail at the design stage for mechanical strength and earthquake resistance, and providing the float 6 in the floating chamber 30 makes the above examination result effective as it is. Since it can be used, new problems caused by providing the floating 6 in the existing floating roof storage tank 1, for example, a decrease in the amount of oil stored due to an additive for adding buoyancy, and the vibration mode of the floating roof 120 Can be avoided.

(First application example)
In addition, in this embodiment, it is set as the structure which installs one float 6 in each floating chamber 30, However, It is not limited to this structure.
FIG. 2: has shown schematic sectional drawing of the floating roof of the floating roof type storage tank which concerns on the 1st application example of this invention.
In the figure, a floating roof type storage tank (not shown) is different from the first embodiment in that floating 6a and 6b are provided in each floating chamber 30. Other components are substantially the same as those in the first embodiment.
Therefore, in FIG. 2, the same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The float 6a is an airtight bag having a shape substantially corresponding to the internal shape outside the manhole 36 in each floating chamber 30 of the pontoon 3 in a state where the gas 61 is sealed. In this structure, a plug 63 a for sealing or exhausting 61 is provided. The float 6b is an airtight bag having a shape substantially corresponding to the internal shape inside the manhole 36 in each floating chamber 30 of the pontoon 3 in a state where the gas 61 is sealed. , A structure including a plug 63b for sealing or exhausting the gas 61 is provided.

In this way, by providing a plurality of floats 6a and 6b inside each floating chamber 30 of the pontoon 3, the floats 6a and 6b are miniaturized. Workability at the time of exhausting can be improved. In addition, when one of the floats 6a (6b) is damaged, the other float 6b (6a) can generate buoyancy, so even in such a case, the two floats 6a and 6b are generated. The buoyancy that is almost half of the buoyancy can be generated. That is, safety can be improved by generating buoyancy in a dispersed manner.
Furthermore, by providing plugs 63a and 63b for enclosing or exhausting the gas 61 around the manhole 36, the floats 6a and 6b can be easily installed inside the floating chamber 30 and can be removed. Therefore, workability can be further improved.

(Second application example)
FIG. 3: has shown schematic sectional drawing of the floating roof of the floating roof type | mold storage tank which concerns on the 2nd application example of this invention.
In the figure, a floating roof type storage tank (not shown) is provided with floating 6c, 6d, 6e in each floating chamber 30 and connecting the floating 6c, 6d, 6e with a tube 67 as compared with the first embodiment. However, the point that the valve 64 is provided for each of the floats 6c, 6d, and 6e is different. Other components are substantially the same as those in the first embodiment.
Therefore, in FIG. 3, the same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The floats 6c and 6e are provided with a joint 65a as a stopper, and the float 6d is provided with a joint 65b as a stopper. Each joint 65a is connected to the joint 65b via a tube 67 and a valve 64, and the joint 65b is connected to a valve 64 and a cap 66. In this way, all the valves 64 can be opened to efficiently enclose or exhaust gas into the plurality of floats 6c, 6d, 6e, and gas 61 is encapsulated into the plurality of floats 6c, 6d, 6e. When all the valves 64 are closed, the gas 61 is sealed for each of the floats 6c, 6d, and 6e. Therefore, even if one float 6 breaks and loses buoyancy, the remaining float 6 maintains the buoyancy. can do.

The plurality of floats 6a, 6b, 6c, 6d, and 6e installed in the floating chamber 30 are not limited to the above configuration, and, for example, four or more floats may be provided. Further, the shape of the float is not limited to the division in the radial direction when the floating roof 120 is a circle, and may be divided in the circumferential direction or in the vertical direction, for example. Further, the floats 6a, 6b, 6c, 6d, and 6e are floats made of a bag-like member in which the gas 61 is sealed. For example, a lightweight member having a gap with respect to a corner portion or a welded portion of the float chamber 30. It is good also as a structure which provides the float 6a, 6b, 6c, 6d, 6e together with the float 6a, 6b, 6c, 6d, 6e while being sealed by the float which consists of, and a sealing member, and consisting of the lightweight member which has a space | gap.
Further, since the bag-like members of the plurality of floats 6a, 6b, 6c, 6d, and 6e have flexibility, the floats 6a, 6b, 6c, 6d, and 6e are used by using special connection members or guides. Even if they are not connected, they can move to a predetermined position and generate buoyancy.

[Second Embodiment]
Next, with reference to FIG. 4, a floating roof type storage tank in which a float made of a sealing member in which foamed resin is sealed as a lightweight member is disposed on the lower surface of the pontoon will be described.
FIG. 4: has shown schematic sectional drawing of the floating roof of the floating roof type storage tank which concerns on 2nd embodiment of this invention.
In the figure, a floating roof type storage tank (not shown) has a lightweight member 71 sealed on the lower surface of the pontoon 3 instead of the float 6 provided inside the pontoon 3 as compared with the first embodiment. Except for the point that the float made of the sealed member 72 is provided, the configuration is substantially the same as the floating roof storage tank of the first embodiment.
Therefore, in FIG. 4, the same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

Specifically, the pontoon 3c of the floating roof 120c shown in FIG. 4 includes an outer rim plate 31c, an inner rim plate 32c, a pontoon lid plate 33c, and a pontoon bottom plate 34c, and each floating chamber 30c is partitioned by a partition plate 35c. Yes.
The pontoon bottom plate 34c is provided on substantially the same plane as the deck 122, and a steel plate guide plate 37 for storing the float 7 is formed in a substantially rectangular ring on the lower surface of the pontoon bottom plate 34c of each floating chamber 30c. Projected to
Although not shown, a chain or a holding plate may be provided on the guide plate 37 so that the float 7 does not fall when the liquid is pulled out of the floating roof storage tank.

The float 7 includes a lightweight member 71 and a sealing member 72 in which the lightweight member 71 is sealed.
For the lightweight member 71, a foam material such as foamed polystyrene, foamed urethane, foamed polyurethane, or the like is used. In the present embodiment, for example, a rectangular flat plate-shaped foam material that is commercially available as a heat insulating material for construction is used. As described above, by using the foam material, although not shown, buoyancy is generated by the fine voids included in the foam material, so that the reliability of the float can be improved. The lightweight member 71 is not limited to the foamed material, and may be any member that is lightened by having a gap isolated from the outside, and examples thereof include foamed aluminum.
In addition, although the float 7 of this embodiment is used in the state which sealed the lightweight member 71 which consists of the said foaming material with the sealing member 72, the mechanical strength, oil resistance, durability, etc. of the lightweight member 71 are floated. When satisfying the specifications of the roof-type storage tank, the lightweight member 71 may be used as a float that directly contacts the liquid.

The sealing member 72 is a sheet-like or bag-like member based on rubber or resin, and is filled with degassed or inert gas so that no air exists between the sealing member 72 and the lightweight member 71 Then, the lightweight member 71 is sealed.
As the material of the sealing member 72, the above-described rubber sheet with a reinforcing cloth is used. In this case, when the liquid stored in the floating roof type storage tank 1 is a flammable substance such as oil, safety is improved because no sparks are generated due to collision or sliding with metal like NBR. be able to.

Further, since the float 7 is compared with the float 6, the lightweight member 71 itself generates buoyancy, so that the thickness of the sealing member 72 can be made slightly smaller than the thickness of the bag-like member 62.
Although not shown, when a plurality of floats 7 are connected, the sealing member 72 may be provided with, for example, a connection hole that allows a connecting rope or the like to pass therethrough. Can be linked.
In addition, when using the sealing member 72 for the purpose of collecting a plurality of lightweight members 71, the airtightness of the sealing member 72 is not required.

  Thus, according to the floating roof type storage tank according to the present embodiment, for example, a long-period earthquake that matches the natural frequency of the floating roof 120 occurs, and the buoyancy caused by the floating chamber 30c is lost due to a large sloshing. Even if it is broken, the lost buoyancy is generated by the float 7 in a supplementary manner, so that it is possible to prevent the problem that the floating roof 120 sinks.

As mentioned above, although the preferred embodiment was shown and demonstrated about the floating roof type storage tank of this invention, the floating roof type storage tank which concerns on this invention is not limited only to embodiment mentioned above, The range of this invention Needless to say, various modifications can be made.
For example, in the second embodiment, the float 7 is disposed on the bottom surface of the pontoon 3c. However, the float 7 is disposed on the bottom surface of the deck 122, or the float 7 is disposed on the bottom surfaces of both the pontoon 3c and the deck 122. It is good also as a structure to install.

  As described above, the floating roof type storage tank of the present invention is a technique for preventing the floating roof from sinking by providing various floats when the buoyancy of the pontoon is lost due to an external force such as an earthquake. The floating roof can be suitably used as a floating roof type storage tank that can float on the liquid surface more safely.

The schematic sectional drawing of the floating roof of the floating roof type storage tank which concerns on 1st embodiment of this invention is shown. The schematic sectional drawing of the floating roof of the floating roof type storage tank which concerns on the 1st application example of this invention is shown. The schematic sectional drawing of the floating roof of the floating roof type storage tank which concerns on the 2nd application example of this invention is shown. The schematic sectional drawing of the floating roof of the floating roof type storage tank which concerns on 2nd embodiment of this invention is shown. The schematic sectional drawing of the common floating roof type storage tank concerning a prior art example is shown. The schematic expanded sectional view of the principal part in the floating roof of the floating roof type storage tank concerning a prior art example is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Floating roof type storage tank 3, 3c Pontoon 4 Sealing device 5 Guide pole 6, 6a, 6b, 6c, 6d, 6e Floating 7 Floating 30, 30c Floating chamber 31, 31c Outer rim plate 32, 32c Inner rim plate 33, 33c Pontoon cover plate 34, 34c Pontoon bottom plate 35, 35c Partition plate 36 Manhole 37 Guide plate 61 Gas 62 Bag-like member 63, 63a, 63b Plug 64 Valve 65a, 65b Joint 66 Cap 67 Tube 110 Tank body 111 Side wall 120, 120c Floating roof 121 compression ring 122 deck

Claims (9)

In a floating roof type storage tank comprising a tank body for storing liquid, and a floating roof having a pontoon that floats on the liquid stored in the tank body and is stored in the tank body,
One or two or more floats are provided in the pontoon and / or in the lower part of the floating roof.   The float is a float of a bag-shaped member sealed with gas, a float of a lightweight member having a gap, and / or a float of a lightweight member having a gap while being sealed by a sealing member. The floating roof type storage tank according to 1.   The floating roof type storage tank according to claim 2, wherein the material of the bag-like member is a composite material having a base material made of rubber or resin and a reinforcing material.   4. The floating roof type storage tank according to claim 2, wherein the bag-like member is provided with a stopper for sealing or exhausting gas.   The floating roof storage tank according to claim 4, wherein compressed gas is supplied to the bag-shaped member.   The floating roof type storage tank according to claim 4 or 5, wherein a plurality of plugs of the bag-like members are connected by piping, and a valve is provided for each bag-like member.   The floating roof type storage tank according to any one of claims 2 to 6, wherein the lightweight member is a foam material.   A float made of a plurality of the bag-like members is provided inside the pontoon, and a plug for sealing or exhausting the gas provided in the bag-like member is disposed around the inspection port of the pontoon. The floating roof type storage tank according to any one of claims 2 to 7.   The floating roof type storage tank according to any one of claims 1 to 8, wherein the float is connected.

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