JP2020142824A - Vertical installation structure of double shell tank - Google Patents

Abstract

To provide technologies that can vertically install an SF double shell tank with a simple structure.SOLUTION: A tank is placed in a state of surface contact on an installation base board 31 having an upper surface formed on the same surface as the bottom surface of the tank. A shell gap 3b formed between the steel shell 1b and the resin shell 2b on the bottom of the tank has a surface pressure resistance that is greater than the surface pressure that acts on the bottom surface of the tank due to the weight of the tank with content fluid when the tank is placed in the aforesaid state.The surface pressure resistance can be applied by holding by a large number of fine particles 7 whose parts protrude from the surface of a coating film 6 that has been coated and hardened on the surface of the steel shell 1.SELECTED DRAWING: Figure 1

Description

The present invention relates to an installation structure of a tank for storing a liquid, in which a tubular tank having a tubular body and end plates that close both ends thereof is vertically oriented, that is, the axial direction of the body is vertically oriented. It is related to the structure to be installed.

Cylindrical tanks for storing liquids are used to store fuel oil such as kerosene and gasoline, and clean water, and are usually buried in the basement of the site where the building was built. Cylindrical tanks are usually installed horizontally, i.e. with the barrel axis horizontal. In the past, liquid tanks buried underground were also placed horizontally, but due to the narrowing of the building site in the city and the accompanying increase in the height of the building, a tubular tank with the required capacity is placed horizontally on the building site. It is becoming impossible to install in a vertical position, and there is an increasing demand for vertical installation in which tanks of the same capacity can be installed in a smaller area.

As a structure for vertically installing a tubular tank, a structure is known in which a skirt-shaped support base is attached to the tank and the support base is fixed to a concrete substrate with anchor bolts or the like. As shown in FIG. 7, the support base 36 has a structure in which a collar 38 is provided on the lower side of the short cylindrical portion 37 that supports the tank 10, and is made of steel in a tank in which the inside of the upper side of the short cylindrical portion 37 is vertically placed. It is integrated with the tank 10 by welding to the lower end portion of the body 11. The tank provided with the support base 36 is installed vertically by inserting anchor bolts erected on a concrete substrate 31 into bolt holes provided in the collar 38 of the support base and fastening them with nuts.

It becomes difficult for a tank buried underground to detect a liquid leak from the time of burial, that is, a liquid leak in the tank and a groundwater leak into the tank. The tank is buried after undergoing a strict liquid leak inspection, but since there is a risk of liquid leakage due to corrosion after burial or cracks due to ground deformation due to an earthquake, it should be done when liquid leakage occurs. Must be able to detect.

As a means for detecting liquid leakage in the tank after burial, a structure in which the tank has a so-called SF double-shell structure and a detection tube with a liquid detector is provided is recommended. In this structure, the shell of the tank is a double structure of a steel shell (S shell) and a resin shell made of reinforced resin (F shell), and the steel shell and the resin shell are not in close contact with each other and are made of steel. A gap that communicates surface-wise between the steel shell and the resin shell by wrapping a resin film on the shell and spraying reinforced resin on it (hereinafter referred to as "shell gap" within the scope of patent claims). Exists. Then, a detection tube whose lower end opens to the lower part of the shell gap is provided in the tank, and by providing a liquid detector in this detection tube, leakage of the liquid in the tank through the steel shell and groundwater through the resin shell are provided. It is a structure that makes it possible to detect all leaks.

The shell gap must be a completely sealed gap. That is, at the peripheral edge of the shell gap, the steel shell and the resin shell must be in close contact with each other, and the close contact portion must not be peeled off after burying, or a gap communicating with the outside world must not be formed. In a liquid tank, it is essential to provide a gas phase portion (a portion where the liquid does not enter, that is, a portion above the liquid surface) in the upper part of the tank, and the contact portion 5 between the steel shell 1 and the resin shell 2 is this air. It is provided in the phase part. That is, the resin shell in the SF double-shell tank has a structure in which the resin shell is in close contact with the steel shell at the upper part of the tank and covers the steel shell with a shell gap between the resin shell and the liquid phase portion. ..

As a method of forming a resin shell on a steel shell, the applicant of the present application applies, in Patent Document 1, a rust preventive paint mixed with fine particles on the steel shell, and then forms the resin shell by conventional means. We are proposing a technology to prevent the occurrence of moire patterns due to the formation of dew condensation in the shell gaps and the harmful effects on ultrasonic inspection of the shells.

The fine particles in the above proposal are organic materials such as nylon resin, polyethylene resin, ethylene vinyl acetate resin, and polyester resin, and inorganic materials such as sand and glass, preferably crushed oil-resistant and water-resistant organic materials. Be done. The size of the fine particles may be such that a part of the fine particles protrudes from the surface of the rust preventive paint, and is about 75 to 500 μm in the case of 50 to 100 μm, which is the general coating thickness of the rust preventive paint.

Further, Patent Documents 2 and 3 show a structure in which a tubular tank having an SF double-shell structure is installed vertically without providing a support base on the tank.

Japanese Unexamined Patent Publication No. 2006-1607 Japanese Patent No. 6192148 Japanese Patent No. 6192149

As mentioned above, there is a demand for burying a tubular liquid tank vertically. On the other hand, there is a demand to adopt the SF double-shell structure from the viewpoint of detecting liquid leakage. However, when the SF double-shell tank is used, the outer peripheral surface of the tank becomes a resin shell, so that it is not possible to adopt a support base having a structure of welding with the steel shell.

Further, since the resin shell is relatively easily deformed by external pressure, even if an attempt is made to adopt a structure in which the upper surface of the substrate on which the tank is placed has the same shape as the end plate at the bottom of the tank, the conventional general structure is used. In the SF double-shell tank, the shell gap 3b on the bottom surface of the tank is crushed by the weight of the tank itself, and the liquid leaking into the shell gap is prevented from flowing down to the bottom of the shell gap. Will not be able to detect liquid leakage. Further, when the shell gap 3b at the bottom is crushed and the steel shell 1 and the resin shell 2 are in close contact with each other, there is a problem that liquid leakage due to corrosion or cracks generated in the close contact portion cannot be detected.

Due to such various problems, it is necessary to adopt a complicated installation structure as proposed in Patent Documents 2 and 3, which hinders the widespread use of the vertical tubular tank. An object of the present invention is to provide a technique capable of vertically installing an SF double-shell tank with a simpler structure.

The vertical installation structure of the double-shell tank of the present invention provides a shell gap 3 between the steel shell 1 located inside the tank 10 and the resin shell 2 located outside, and communicates with the bottom of the shell gap. The structure is such that the SF double-shell tank is installed vertically so that the liquid detector provided in the detection pipe 21 can detect the leakage of the liquid in the tank from the steel shell 1 and the leakage of the groundwater from the resin shell 2.

The shell gap 3b on the bottom surface of the tank in the installation structure of the present invention is based on the surface pressure acting on the bottom surface of the tank due to the weight of the tank containing the content liquid when the bottom surface 12s of the tank is placed in surface contact with the top surface of the installation substrate 31. It has a large surface pressure resistance. The tank is placed on the installation board 31 in a state where the bottom surface of the reinforced resin of the tank and the upper surface of the installation board 31 having the upper surface formed on the same surface as the bottom surface are in surface contact with each other.

The surface pressure required for the resin shell 2b on the bottom surface of the tank is a large number of fine particles 7 that partially protrude from the surface of the coating film 6 that has been cured by coating the shell gap 3b on the bottom surface of the tank on the surface of the steel shell 1. Can be granted by holding by.

The bottom surface 12s of the tank and the top surface of the installation substrate 31 in surface contact with the bottom surface 12s are preferably horizontal. Further, it is preferable to interpose the cushion material 32 between the bottom surface of the tank and the installation board. As a result, the surface pressure acting on the resin shell 2b on the bottom of the tank from the installation board can be made uniform, and the shell gap 3b on the bottom of the tank can be partially crushed due to the shape error between the bottom of the tank and the top of the installation board. It can be prevented.

A flange plate 23 for closing the through hole 22 provided in the steel shell is welded to the lower end of the detection tube 21 that opens in the shell gap 3b at the bottom of the tank, and from the through hole 22 provided with the communication hole 25 communicating with the lower end of the detection tube 21. A small diameter plate 24 having a small diameter is welded to the lower surface of the flange plate 23 to provide a detection tube 21.

According to the present invention, there is an effect that an SF double-shell tank capable of detecting a liquid leak in a tank and a leak of groundwater in the ground where the tank is installed can be installed in the ground with an extremely simple structure.

Cross-sectional side view showing the first embodiment of this invention Detailed cross section of the shell gap Cross-sectional view showing the joint structure between the lower end of the leak detection pipe and the steel shell Cross-sectional side view showing an example of a tank lift prevention means Top view of FIG. A diagram similar to FIG. 1 showing an embodiment in which the bottom end plate is bowl-shaped. Cross-sectional side view showing the main parts of the conventional structure in which the steel tubular tank is installed vertically.

1 to 3 are views showing a first embodiment of the present invention. In the tank of the first embodiment, the bottom end plate 12 as the bottom surface is flat, and the upper end plate 13 is a general arm-shaped end plate. The tank 10 is an SF double-shell tank in which a resin shell 2 is provided on the outside of the steel shell 1, and a shell gap 3 exists between the steel shell 1 and the resin shell 2. Although it is exaggerated in the figure, the shell gap 3 is a gap of several tens to several hundreds of μm.

The resin shell 2 is in close contact with the steel shell 1 with a sufficient width in the gas phase portion above the maximum liquid level L of the tank. Since the steel shell of the contact portion 5 has a simple shape and a smooth surface, a highly reliable contact state between the steel shell and the resin shell can be easily realized. The shell gap 3 between the steel shell 1 and the resin shell 2 is formed in the body 11 and the bottom end plate 12 of the tank by the method described in Patent Document 1.

That is, in the close contact portion 5 in which the steel shell 1 and the resin shell 2 are brought into close contact with each other, the surface of the steel shell is subjected to a base treatment such as sandblasting to be primed, and the resin shell that is sprayed onto the hardened resin shell is brought into close contact with the steel shell. Let me. In the body 11 and the bottom end plate 12 provided with the shell gap 3, a rust preventive paint mixed with fine particles 7 is applied to the surface of the steel shell 1, and a paint layer 8 in which a part of the fine particles 7 protrudes from the surface 6s of the cured coating film 6. Is formed, and after the resin film 4 is further wound, the reinforcing resin is sprayed to cover the resin shell 2.

As described above, the body 11 and the bottom end plate 12, which are the liquid phase portions, are hermetically sealed between the resin shell 2 and the steel shell 1 that have shrunk during the coating formation, due to the close contact between the steel shell and the resin shell in the gas phase portion A. A shell gap 3 corresponding to the height h of the fine particles 7 protruding from the surface 6s of the coating film, which is a gap and is communicated in a plane, is formed.

The upper end plate 13 of the tank is provided with two manholes 14 and 15 for piping and inspection. In order to compensate for the lack of strength due to the bottom end plate 12 being formed on a flat plate, reinforcing ribs 16 are provided on the bottom surface of the tank in a grid shape, and these reinforcing ribs are used to allow the liquid at the bottom of the tank to flow. The through hole 17 is provided.

The detection tube 21 containing a liquid detector (not shown) for detecting the liquid leaked into the shell gap 3 has a lower end welded to the bottom surface of the steel shell and opens at the lowermost part of the shell gap 3. The upper end is pulled out through the upper end plate 13. The detection signal line of the liquid detector is drawn from the upper end of the detection tube 21 and connected to a liquid leak detector (not shown).

FIG. 2 is an enlarged view of the shell gap portion. As shown in the figure, the cured coating film 6 is attached to the surface of the steel shell 1, and a large number of fine particles 7 mixed with the coating film are present in a state of protruding from the surface 6s of the coating film. The surface pressure resistance of the bottom surface of the tank can be increased by using fine particles having high crushing strength, increasing the mixing ratio of the fine particles 7 per unit area, and using particles having a relatively large diameter as the fine particles 7. .. That is, a large number of fine particles 7 protruding from the coating film surface 6s on the bottom surface of the tank oppose each other without being crushed by the external force acting on the resin shell 2b on the bottom surface, and the surface pressure is such that the shell gap 3 is maintained without being crushed. Can be designed.

The value obtained by dividing the weight of the tank when the liquid is full by the contact area between the substrate 31 provided underground to install it and the bottom surface of the tank is the resin shell when the tank is placed on the substrate 31. It is the maximum surface pressure applied to the bottom surface 12s of the. If the material and size of the fine particles 7 and the mixing ratio with the paint are designed so that the calculated maximum surface pressure is sufficiently smaller than the surface pressure resistance of the resin shell 2b on the bottom surface of the tank, the tank can be placed on the substrate 31. It is possible to prevent the shell gap 3b on the bottom surface of the tank from being crushed and the steel shell and the resin shell from coming into close contact with each other in the mounted state.

FIG. 3 is a diagram showing a welded structure to the bottom surface 1b of the steel shell at the lower end of the detection tube 21. The shell gap 3 is very narrow. Therefore, if the lower end of the detection tube 21 or the protruding portion of the welding line in which the lower end is welded to the steel shell protrudes outward even a little from the outer surface of the steel shell 1b at the bottom, a problem arises. Further, it is necessary to inspect the liquid leakage at the welded portion between the lower end of the detection tube 21 and the steel shell 1b. Due to this necessity, the detection tube 21 is welded to the steel shell 1b by the following procedure.

That is, a relatively large through hole 22 is provided in the portion of the steel shell 1b to weld the lower end of the detection tube 21, and a flange plate 23 having a size for closing the through hole 22 is welded to the lower end of the detection tube 21. Keep it. Then, the detection tube 21 is inserted into the tank and the steel shell 1b around the flange plate 23 and the through hole 22 is welded. In this state, fill the tank with liquid and check whether the liquid leaks from the lower end of the detection tube 21 and the periphery of the collar plate 23. After confirming that there is no leakage, the small diameter plate 24 provided with the communication hole 25 communicating with the detection tube 21 is welded to the collar plate 23. Even if there is a leak in the last welded portion 26, the leak is a leak between the shell gap 3 and the inside of the detection tube 21, and there is no problem in detecting the leak.

As shown in FIG. 1, the tank 10 manufactured in this manner is placed and installed on a substrate 31 having a flat horizontal surface on the upper surface. In FIG. 1, a thin cushion material 32 is provided between the upper surface of the substrate 31 and the bottom surface of the tank. The cushion material 32 is effective in equalizing the surface pressure between the upper surface of the substrate and the bottom surface of the tank.

Since the bottom surface of the tank is flat, it can be stably installed on the substrate 31, but since the buoyancy of the groundwater acts on the tank to be buried, a means for preventing the tank from floating is required. In the horizontal tank, a belt or a wire having both ends fixed to the substrate 31 is laid over the upper part of the tank 10 to prevent the tank 10 from floating. The same levitation prevention structure can be adopted in the vertical installation structure shown in FIG. 1, but as shown in FIGS. 4 and 5, the shoulder portion of the tank 10 is pressed by the arm 34 to prevent levitation. You can also.

In the examples of FIGS. 4 and 5, the tank 10 is placed on the substrate 31 provided at the bottom of the storage hole dug above the ground. A plurality of pillars 41 are erected around the substrate 31, and a lid 42 forming a ground surface GS is provided at the upper end of the pillars. The arm 34 that prevents the tank 10 from floating is fixed to the upper ends of a plurality of stays or frames 33 whose lower ends are fixed to the substrate 31, and extends toward the shoulder portion of the tank 10. After installing the tank 10, earth and sand are backfilled around the tank inside the storage hole.

The first embodiment shown in FIG. 1 has a structure in which the bottom surface of the tank is a flat surface, and since the upper surface of the substrate 31 can be a flat surface in this structure, the surface between the bottom surface of the tank and the upper surface of the substrate 31. It is effective in equalizing the pressure. However, the main point of the present invention is a structure in which the bottom surface of the tank is placed on the upper surface of the substrate 31 having the same shape and the shell gap 3b between the steel shell and the resin shell is not crushed. Therefore, if the upper surface of the bottom end plate 12 and the substrate 31 can be formed with sufficient accuracy, it does not necessarily have to be flat.

For example, as shown in FIG. 6, a substrate 31 having a bowl shape similar to that of the upper end plate 13 and an upper surface having the same shape as the bottom surface 2b of the resin shell installed outside the bottom end plate 12 of the tank is manufactured. The tank can be installed with the same structure as in FIG.

In this example, the lower end of the detection tube 21 opens in the center of the bottom end plate 12. In this case, the upper surface of the substrate 31 is set with an error such that the central portion is slightly deeper than the shape of the lower surface of the resin shell so that the portion where the surface pressure is lowered due to the error comes to the center of the installation surface. preferable. In the structure of the present invention, since the entire shell gap 3b on the bottom surface of the tank becomes a flow path for the leaked liquid, the flow path area becomes narrower as it is closer to the connection position of the detection tube 21. Therefore, in order to secure the flow path, the shape error between the bottom surface of the tank and the top surface of the substrate 31 should be an error distribution such that the surface pressure of the portion to which the detection tube 21 is connected becomes low, and is stable against the fall of the tank. Such an error distribution is also preferable in terms of sex.

1 Steel shell 2 Resin shell 2b Resin shell on the bottom of the tank 3 Shell gap 3b Shell gap on the bottom of the tank 6 Coating film 7 Fine particles 7
10 Tank 12s Tank bottom 21 Detection tube 22 Through hole 23 Btsuba plate 24 Small diameter plate 25 Communication hole 31 Installation board 32 Cushion material

Claims (4)

A liquid detector provided in a detection tube that has a shell gap between the steel shell located inside the tank and the resin shell located outside and communicates with the bottom of the shell gap, and leaks from the steel shell and the resin shell. In the vertical installation structure of the SF double shell tank that can detect
The shell gap on the bottom of the tank has a surface pressure resistance that is not crushed by the pressure acting on the resin shell.
It has a surface pressure resistance that is greater than the surface pressure that acts on the bottom surface of the tank due to the weight of the tank containing the contents liquid when the bottom surface of the tank is placed in surface contact with the top surface of the substrate.
A vertical installation structure of a double-shell tank in which the tank is placed on the substrate in a state where the bottom surface of the reinforced resin of the tank and the upper surface of the substrate formed on the same surface as the bottom surface are in surface contact with each other. The vertical installation structure according to claim 1, wherein the shell gap on the bottom surface of the tank is held by a large number of fine particles partially protruding from the surface of the coating film coated and cured on the surface of the steel shell. .. The vertical installation structure according to claim 1 or 2, wherein the bottom surface of the tank is a horizontal plane. The lower end of the detection tube 21 that opens in the shell gap 3 at the bottom of the tank is welded with a collar plate that closes the through hole provided in the steel shell, and a small diameter plate with a smaller diameter than the through hole provided with the communication hole that communicates with the lower end of the detection tube. The vertical installation structure according to claim 1, 2 or 3, which is provided by welding to the lower surface of the flange plate.

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