JP5126619B2 - Underground tank and manufacturing method thereof - Google Patents

Description

  The present invention relates to an underground tank buried in the ground and a method for manufacturing the same, and more particularly to an underground tank for storing fuel oil supplied to an automobile.

  The tank of the gas station that stores the fuel oil is buried in the ground. If this tank is damaged and fuel oil flows out, it is dangerous and environmental destruction. For this reason, in the conventional underground tank, as shown in FIG. 7, a double shell comprising an inner shell 51 and an outer shell 52 is provided, and a leak detection space 53 through which the detection liquid flows is interposed therebetween. The leak detector 54 is configured to detect the leakage of the detection liquid and monitor the presence or absence of damage.

  In such a double shell tank, both the inner and outer shells 51 and 52 are made of steel, the inner shell 51 is made of steel, and the outer shell 52 is made of glass fiber reinforced plastic (hereinafter referred to as “FRP”). Furthermore, there is one in which both the inner and outer shells 51 and 52 are made of FRP. Among these, double-shell tanks in which both the inner and outer shells are made of FRP are lightweight and highly corrosion-resistant, and are rapidly spreading.

  However, double-shell tanks with inner and outer shells made of FRP are more flexible and flexible than steel tanks, so they differ in strength from steel tanks, so that they can compensate for earth pressure. It is necessary to take measures to reinforce. Therefore, for example, in Patent Document 1, as shown in FIG. 8, a double shell comprising an FRP inner shell 61 and an FRP outer shell 62 formed through the inner shell 61 and the leakage detection space 63 is provided. In the tank, it has been proposed to attach a ring-shaped reinforcing rib 64 radially inward of the inner shell 61.

JP 2006-117255 A

  However, in the tank buried underground, it is conceivable that water is mixed due to condensation or impurities such as piping and sludge in the tank. In the double shell tank described in Patent Document 1, the reinforcing rib 64 Impurities are likely to stagnate in the layer divided by the height position, so that it is necessary to provide a communication port 65 for discharging them (see FIG. 8). This complicates the structure of the reinforcing rib 64 and its surroundings, resulting in a problem that the construction period is prolonged and the manufacturing cost is increased.

  As one means for solving such a problem, it is conceivable to provide reinforcing ribs on the outer peripheral surface (outside of the tank) of the outer shell to avoid the formation of irregularities inside the tank. However, even in this case, since irregularities are generated on the outside of the tank, the structure of the foundation supporting the tank is forced to be devised and improved, and new measures are required. In addition, because of the relationship with the foundation and the depth of soil digging, the height of the reinforcing ribs must be lowered, so in order to ensure sufficient strength, it is necessary to increase the number of reinforcing ribs, On the contrary, there is a risk of increasing the cost.

  Further, in the conventional double shell tank, as shown in FIG. 7, since the leakage detection space 53 is provided between the inner shell 51 and the outer shell 52, even if leakage of the detection liquid (damage to the tank) is detected. It is impossible to grasp which of the inner shell 51 and the outer shell 52 is damaged. For this reason, every time a leak is detected, the tank has to be dug to check the damaged part, and there has been a problem that repair work is very time-consuming.

  Therefore, the present invention has been made in view of the problems in the conventional technology described above, and provides an underground tank or the like that can ensure strength with a simple configuration and can reduce the labor of repair work. The purpose is to do.

In order to achieve the above object, the present invention is an underground tank that has an inner shell and an outer shell made of FRP and is buried in the ground, and is disposed outside the inner shell and flows inside the first tank . A first detection layer for detecting damage to the inner shell based on a change in the liquid level of the detection liquid, and a change in the liquid level of the second detection liquid disposed inside the outer shell and flowing inside the first detection layer. A second detection layer for detecting damage to the outer shell based on the first detection layer, and a buffer reinforcement layer made of resin disposed between the first and second detection layers . The detection layer is formed of a three-dimensional glass fiber fabric in which a surface perpendicular to the longitudinal direction of the underground tank has a low density and a surface parallel to the longitudinal direction has a high density .

According to the present invention, since the resin-made buffer reinforcement layer is provided between the inner shell and the outer shell, the necessary strength can be ensured without forming reinforcing ribs inside or outside the underground tank. It is possible to ensure strength with a simple configuration. In addition, since the first and second detection layers are provided, it is possible to immediately grasp which of the inner shell and the outer shell is damaged, and it is possible to reduce the labor of repair work.
Further, according to the present invention, the first and second detection layers are formed of a three-dimensional glass fiber fabric in which a surface perpendicular to the longitudinal direction of the underground tank has a low density and a surface parallel to the longitudinal direction has a high density. Therefore, it is possible to appropriately form a space inside the first and second detection layers, and at the same time, it is possible to improve the strength of the first and second detection layers.

  In the underground tank, the buffer reinforcement layer can be formed of a foamed resin or a foamed nonwoven fabric. When the buffer reinforcing layer is made of foamed resin, for example, foamed polyurethane, foamed polyethylene, foamed polypropylene, foamed polystyrene, or foamed ABS resin can be used.

  In the above underground tank, glass mats may be disposed on both sides of the buffer reinforcing layer, and the glass mats may be sewn with glass fibers. According to this, it is possible to protect the buffer reinforcement layer, and it is possible to improve the bonding strength between the buffer reinforcement layer and the first and second detection layers.

  The underground tank may have a partition part for partitioning the internal space of the underground tank, and the partition part may include a detection layer for detecting damage to the partition part. It becomes possible to detect and detect damage.

The present invention also relates to a method of manufacturing an underground tank buried in the ground, the step of forming an inner shell made of FRP, and the liquid level of the first detection liquid flowing inside the inner shell. It is made of a three-dimensional glass fiber woven fabric having a low density surface perpendicular to the longitudinal direction of the underground tank and a high density surface parallel to the longitudinal direction for detecting damage to the inner shell based on the change in Forming a first sensing layer; molding a middle shell provided with a resin-made buffer reinforcement layer on the first sensing layer; and second flowing inside the middle shell . Three-dimensional glass for detecting damage to the outer shell based on a change in the level of the detection liquid, with a surface perpendicular to the longitudinal direction of the underground tank having a low density and a surface parallel to the longitudinal direction having a high density a step of forming the second sensing layer made of fiber fabric, the outer shell made of FRP on the second sensing layer Characterized by a step of molding.

  As described above, according to the present invention, it is possible to provide an underground tank capable of ensuring strength with a simple configuration and reducing the labor of repair.

It is sectional drawing which shows 1st Embodiment of the underground tank which concerns on this invention. It is an enlarged view of the A part of FIG. It is a figure for demonstrating the repair method of the underground tank of FIG. It is sectional drawing which shows 2nd Embodiment of the underground tank which concerns on this invention. It is a figure which shows the other example of the partition part of FIG. It is a figure which shows the other example of the partition part of FIG. It is sectional drawing which shows an example of the conventional underground tank. It is sectional drawing which shows the conventional underground tank provided with the reinforcement rib.

  Next, an embodiment for carrying out the present invention will be described in detail with reference to the drawings.

  FIGS. 1 and 2 show a first embodiment of an underground tank according to the present invention. The underground tank 1 is a substantially cylindrical large container, and in order from the inside toward the outside, 1 detection layer 3, middle shell 4, second detection layer 5 and outer shell 6 are laminated.

  The inner shell 2 and the outer shell 6 are made of FRP, and corrosion resistant layers 2a and 6a for preventing deterioration of the inner shell 2 and the outer shell 6 are formed on the surfaces thereof as shown in FIG.

  The first detection layer 3 is provided to detect damage to the inner shell 2, and as shown in FIG. 2, the glass fiber 3a is three-dimensionally woven and the glass fiber 3a is impregnated with a resin. It is made of glass fiber fabric. This three-dimensional glass fiber fabric is formed by entwining glass fibers 3a into a sheet shape, and is configured such that the detection liquid flows in a space 3b formed between the fibers 3a and 3a.

  In the 1st detection layer 3, in the surface orthogonal to the longitudinal direction of the underground tank 1, the glass fiber 3a is arrange | positioned by low density, the space 3b is enlarged, and the fluidity | liquidity of the detection liquid to a longitudinal direction is improved. On the other hand, on the surface parallel to the longitudinal direction, the glass fibers 3a are arranged at a high density, ensuring high strength and causing the first detection layer 3 to function as one of the reinforcing members.

  As shown in FIG. 1, the first detection layer 3 is connected to a first leakage detector 7 that detects a change in the level of the detection liquid. When the inner shell 2 is damaged and the detection liquid leaks and the liquid level is lowered, the fact is transmitted to the monitor (not shown) through the first leak detector 7, and the inner shell 2 is damaged. Informed.

  The second detection layer 5 is provided for detecting damage to the outer shell 6. The second detection layer 5 has the same configuration as that of the first detection layer 3, and is formed of a three-dimensional glass fiber fabric in which glass fibers 5a are three-dimensionally woven as shown in FIG. Further, as shown in FIG. 1, the second detection layer 5 is connected to the second leak detector 8, and the detector 8 detects a change in the level of the detection liquid flowing through the second detection layer 5. Is done.

  The inner shell 4 is provided to supplement the strength of the shell plate of the underground tank 1, and as shown in FIG. 2, a buffer reinforcing layer 4a is arranged at the center, and glass mat layers 4b and 4c are formed of glass fibers on both sides thereof. It has a stitched sandwich structure.

  The buffer reinforcing layer 4a is provided to increase the thickness of the underground tank 1 to improve the overall strength, and at the same time, reduce the impact and load on the underground tank 1. As cushioning members, resin members such as hard vinyl chloride, hard polyurethane, foamed polystyrene, foamed urethane and foamed urethane, and wooden members such as control panels, balsa and paper are known, but they are assumed to be used in the underground tank 1 Then, the buffer reinforcing layer 4a has (1) retention of rigidity as a sandwich structure material, (2) dispersion and buffering of pressure against the load from inside and outside, (3) weight reduction of the tank, and (4) simplicity of manufacture. For example, it is desirable that the foam base material has a comprehensively integrated advantage.

  Further, since the buffer reinforcement layer 4a does not require a sensor function when the tank is wrinkled by filling the detection liquid or the like, it depends on the spring back after impregnating the glass fiber in the Z-axis direction (plate thickness). There is no need, and the resiliency of the foam material is used, so it becomes simple. However, in order to prevent the resin from being contained in the foamed resin sheet, a sheet having the property of being completely foamed and not being affected by the constituent agent contained in the resin is used.

  Taking them into consideration, the buffer reinforcement layer 4a is preferably formed of a foamed resin, specifically, can be formed of foamed polyurethane, foamed polyethylene, foamed polypropylene, foamed polystyrene, foamed ABS, etc. The thing of the property which is not attacked by the styrene monomer contained can be used. The buffer reinforcing layer 4a can also be formed of a foamed nonwoven fabric in which a plurality of microballoons are encapsulated in a nonwoven fabric.

  The glass mat layers 4b and 4c are provided to protect the buffer reinforcement layer 4a and improve the bonding strength (integration) between the inner shell 4 and the first and second detection layers 3 and 5, and buffer reinforcement. The layer 4a and the glass fiber are sewn together, and the glass fiber on the vertical axis is provided with a structure in which the resin is impregnated. Here, the glass mat refers to a material obtained by binding a large number of ultrafine glass fibers into a cloth shape.

  To improve the rigidity, it is conceivable to increase the glass fiber density and increase the thickness of the sheet (plate). The method of stitching the glass fibers above and below the sheet and forming the glass fiber columnar shape in the Z-axis direction is usually simple by needling.

  In the impregnation of the resin into the substrate thus manufactured, the substrate is supplied between the continuous roller and the belt roller, immersed in the resin tank in a compressed state, and released from the compression, the restoring force of the foamed substrate is used. When returning to the original thickness, resin enters inside. Since the foamed base material is a closed cell, the resin enters only into the glass fiber and through the base material penetration portion, and FRP pillars are formed.

  Furthermore, since the base material has the same curved surface as the mold, a columnar object is formed in a direction perpendicular to the surface, and rigidity is developed. When a vacuum is applied to the tank in the resin impregnation step, the remaining air in the substrate is further discharged, and a columnar object having ideal rigidity is formed. However, if an excessive thickness is required at one time, an incomplete part (insufficient stitched glass joints on the upper and lower surfaces may be formed, and the impregnation of the resin impregnation may be hindered). In some cases, even more rigidity can be expressed by using two or three foam base materials.

  In the production of the underground tank 1 having the above-described configuration, a tubular body is manufactured using a FW (Filament Winding) molding machine, and then both ends (the right side portion and the left side portion) of the underground tank 1 are separately molded. After that, they are joined to complete the whole.

  Specifically, first, the corrosion-resistant layer 2a (wetted layer) serving as the innermost layer is formed on the mandrel of the FW molding machine. As the resin used at this time, a resin having corrosion resistance to the stock solution is used.

  Next, the inner shell 2 is formed on the surface of the corrosion-resistant layer 2a. Next, a large amount of resin is applied on the surface of the inner shell 2, and a three-dimensional glass fiber fabric is wound on the surface of the inner shell 2. As a result, a large amount of resin applied to the surface layer of the inner shell 2 is sucked up into the three-dimensional glass fiber fabric by capillary action. At that time, a springback phenomenon occurs in the glass fiber forming the Z axis of the three-dimensional glass fiber fabric, and the Z axis rises in the vertical direction. At this time, it waits for hardening once, and after complete hardening, the surface of the three-dimensional glass fiber fabric is impregnated with resin to form the first detection layer 3.

  Next, the buffer reinforcing layer 4a covered with the glass mat layers 4b and 4c is wound around the surface of the first detection layer 3, and the inner shell 4 is molded by impregnating the resin. Next, the second detection layer 5 is formed on the surface of the inner shell 4 using the same method as that for the first detection layer 3, and then the outer shell 6 and the corrosion-resistant layer 6a are sequentially formed.

  Finally, the molded parts of the respective parts molded as described above are butt-joined and a manhole, a nozzle or the like (not shown) is attached at a predetermined position, and the underground tank 1 is completed.

  According to the underground tank 1 according to the present embodiment, since the inner shell 4 having the foamed resin cushioning reinforcement layer 4a is provided between the inner shell 2 and the outer shell 6, the weight is significantly increased. The thickness of the underground tank 1 can be increased. Thereby, the strength of the trunk plate itself of the underground tank 1 can be improved, and the necessary strength can be ensured without forming reinforcing ribs inside or outside the underground tank 1. Therefore, the structure of the underground tank 1 can be simplified, and the construction period can be shortened and the manufacturing cost can be reduced.

  Further, since the buffer reinforcement layer 4a in the inner shell 4 functions to absorb the impact and load applied to the underground tank 1 to some extent, for example, when burying the underground tank 1, heavy machinery passes above the underground tank 1 Even if it does, it becomes possible to suppress that the inner shell 2 and the outer shell 6 are damaged.

  Furthermore, since the underground tank 1 includes the first and second detection layers 3 and 5 and a detection layer corresponding to each of the inner shell 2 and the outer shell 6 is provided, when leakage of the detection liquid is detected, It is possible to immediately grasp which of the inner shell 2 and the outer shell 6 is damaged. In addition, since it is possible to grasp whether one of the inner shell 2 and the outer shell 6 is damaged or both of them are damaged, it becomes possible to estimate the degree of damage to some extent, and whether or not repair is necessary. Is easier to judge.

  Then, in repair work, after the worker enters the underground tank 1 and identifies the damaged portion, as shown in FIG. 3, a certain region 9 including the damaged portion is cut from the inside of the underground tank 1, The replacement member 10 having the same shape as the region 9 is applied to the portion (see FIG. 3A). Thereafter, the replacement member 10 is pushed in to push the region 9 outward, and the replacement member 10 and the underground tank 1 are joined (see FIG. 3B). Even if the damaged part is the inner shell 2 or the outer shell 6, the repair work is performed as described above.

  According to this method, even if the work is performed with the underground tank 1 buried in the ground, the underground tank 1 can be repaired without allowing the entry of earth and sand. For this reason, it is not necessary to dig up the underground tank 1 every time repair is performed, and it is possible to reduce the labor of repair work.

  Next, a second embodiment of the underground tank according to the present invention will be described with reference to FIGS. In these drawings, the same components as those in FIGS. 1 and 2 are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 4, the underground tank 20 according to the present embodiment includes a partition portion 22 for partitioning the inside of the trunk portion 21 into a plurality of spaces. The partition portion 22 is joined to the inner wall surface of the body portion 21 and supported by support members 23 disposed on both sides.

  The partition part 22 has a configuration in which a detection layer 22c for detecting damage to the partition part 22 is interposed between the first and second plate layers 22a and 22b made of FRP. The detection layer 22c is formed of a three-dimensional glass fiber fabric in which glass fibers are three-dimensionally woven, and is configured such that the detection liquid flows in a space between the fibers.

  The detection layer 22c is disposed so as to be separated from the first and second detection layers 3 and 5 of the trunk portion 21, and the first and second leakage detectors 7 and 8 (see FIG. 1). Is connected to a dedicated leak detector 24 installed separately. In addition, when arranging the some partition part 22 in the trunk | drum 21, the leak detector 24 is installed for every partition part 22. FIG.

  Here, as shown in FIG. 5, the structure for detecting the damage to the partition 22 is filled with air inside the detection layer 32, and pressure loss is detected by the pressure detector 34, as shown in FIG. As described above, the electrode sensor 42 a and the lead wire 42 b may be disposed inside the detection layer 42, and the detector 44 may be configured to electrically detect damage.

  According to the present embodiment, not only the inner shell 2 and the outer shell 6 of the trunk portion 21 but also the damage of the partition portion 22 can be distinguished and detected, so that the damaged portion can be identified more easily.

  The embodiment of the present invention has been described above, but the present invention is not limited to the above-described configuration, and various modifications can be made within the scope of the invention described in the claims.

  For example, in the above embodiment, the case where fuel oil is stored has been described as an example. However, by changing the material of the corrosion-resistant layers 2a and 6a, it can be widely applied to tanks that store chemicals and the like. is there.

  In the above embodiment, the detection liquid is sealed in the first and second detection layers 3 and 5, but the detection layer is filled with air as in the case shown in FIGS. 5 and 6. It is also possible to detect pressure loss, or to arrange an electrode sensor and a lead wire inside the detection layer to electrically detect damage.

DESCRIPTION OF SYMBOLS 1 Underground tank 2 Inner shell 2a Corrosion-resistant layer 3 1st detection layer 3a Glass fiber 3b Space 4 Middle shell 4a Buffer reinforcement layer 4b, 4c Glass mat layer 5 Second detection layer 5a Glass fiber 5b Space 6 Outer shell 6a Corrosion-resistant layer 7 First Leakage Detector 8 Second Leakage Detector 9 Region 10 Replacement Member 20 Underground Tank 21 Body 22 Partition 22a, 22b Plate Layer 22c Detection Layer 23 Support Member 24 Leak Detector 32 Detection Layer 34 Pressure Detection Detector 42 Detection layer 42a Electrode sensor 42b Lead wire 44 Detector

Claims (6)

An underground tank having an inner shell and an outer shell made of FRP and buried in the ground,
A first detection layer that is disposed outside the inner shell and detects damage to the inner shell based on a change in the level of the first detection liquid flowing in the inner shell;
A second detection layer that is disposed inside the outer shell and detects damage to the outer shell based on a change in the level of the second detection liquid flowing in the inner shell;
A resin-made buffer reinforcement layer disposed between the first and second detection layers ,
The first and second detection layers are formed of a three-dimensional glass fiber fabric in which a surface perpendicular to the longitudinal direction of the underground tank has a low density and a surface parallel to the longitudinal direction has a high density. And underground tank.   The underground tank according to claim 1, wherein the buffer reinforcement layer is formed of a foamed resin or a foamed nonwoven fabric.   3. The underground tank according to claim 2, wherein the buffer reinforcement layer is formed using foamed polyurethane, foamed polyethylene, foamed polypropylene, foamed polystyrene, or foamed ABS.   The underground tank according to claim 2 or 3, wherein glass mats are disposed on both surfaces of the buffer reinforcing layer, and the glass mats are sewn with glass fibers. A partition for partitioning the internal space of the underground tank;
The underground tank according to any one of claims 1 to 4 , wherein the partition portion includes a detection layer for detecting damage to the partition portion. A method of manufacturing an underground tank buried in the ground,
Forming a FRP inner shell;
On the inner shell, a surface perpendicular to the longitudinal direction of the underground tank for detecting damage to the inner shell based on a change in the level of the first detection liquid flowing inside is set to a low density, Forming a first sensing layer made of a three-dimensional glass fiber fabric having a high density parallel to the longitudinal direction ;
Forming a middle shell provided with a resin-made buffer reinforcement layer on the first detection layer;
On the inner shell, a surface perpendicular to the longitudinal direction of the underground tank for detecting damage to the outer shell based on a change in the level of the second detection liquid flowing inside is set to a low density, and the longitudinal Forming a second sensing layer made of a three-dimensional glass fiber fabric having a high density parallel to the direction ;
Forming an outer shell made of FRP on the second detection layer.

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