JPH1135090A - Acid water tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the material and constructing costs and to shorten the construction period by making a side wall and a bottom wall into unit panels with peripheral flanges wherein an inner wall face of a unit panel made of FRP with peripheral flanges and contact regions between the flanges are covered with a shallow box-like body comprising rigid vinyl chloride plates. SOLUTION: A unit panel 1A coated with rigid vinyl chloride is used as a side wall TB and a bottom wall TC. An FRP unit panel 11 is placed on an external face, while a rigid vinyl chloride coat 15A is placed on an internal face. A ceiling unit panel TD1 comprises an FRP unit panel 15D placed on an external face and lined anti-corrosive resin 11D placed on an internal face. A manhole unit panel TD2 comprises an FRP unit panel 15E on an external face and lined anti-corrosive resin 11D placed on an internal face. A manhole inner lid 1F with the anti-corrosive resin 11D lined on an internal face of an FRP manhole inner lid 15F is put over a manhole MH, and an FRP manhole outer lid 1G is put on it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a tank for storing acidic water obtained by electrolyzing water.

[0002]

2. Description of the Related Art Acidic water obtained by electrolyzing water includes P
H of about 2.0 to 6.0 can be considered. As a conventional acidic water tank for storing such acidic water,
There are known tanks made of hard vinyl chloride, and tanks in which the inner surface of a concrete wall or the inner surface of a steel plate wall is lined with vinyl chloride.

[0003]

However, the rigid vinyl chloride tank has to meet the problem that the thickness of the rigid vinyl chloride plate must be increased in order to secure the water pressure resistance and the shape of the tank. Thus, there is a problem that hard vinyl chloride must be processed into a complicated shape.
Further, a tank in which the inner surface of a concrete wall or the inner surface of a steel plate wall is lined with vinyl chloride has a problem in that the lining work is performed at the site where the tank is installed, so that the work is troublesome and the construction period becomes longer.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems. First, in a tank comprising a unit panel with a four-circle flange, a side wall and a bottom wall are made of an FRP with a four-circle flange. A tank for acidic water, characterized in that the inner wall surface of the unit panel and the contact area between the flanges are unit panels with a four-circumferential flange in which a shallow box-shaped body made of a hard vinyl chloride plate is used. And
The shallow box may be formed by vacuum forming, the contact area between the flanges may be the inner area of the bolt hole of the four-circle flange, or the contact area between the flanges may be the entire area of the four-circle flange. There may be some.

[0005] Second, in a tank formed by combining flanges of a unit panel with a four-circle flange and a manhole panel with a four-circle flange, the side wall and the bottom wall are connected to the inner wall surface of the FRP unit panel with a four-circle flange and the flange. The contact area is a unit panel with a four-circle flange covered with a shallow box made of hard vinyl chloride plate, and the manhole wall and / or ceiling wall is lined with a corrosion-resistant resin on the inner surface of the FRP unit panel with a four-circle flange. Unit panel with a four-circle flange, the manhole cover has a dual structure of an inner lid and an outer lid made of FRP lined with a corrosion-resistant resin on the inner surface of the FRP lid, at the first, second and third positions Provided is a tank for acidic water, wherein acidic water is provided with watertight piping. And the shallow box-shaped body may be formed by vacuum forming, the contact area between the flanges may be the inside area of the bolt hole of the four-circle flange, or the contact area between the flanges may be the four-circle flange. The whole area may be used.

[0006] Further, providing water-tight piping to the acidic water at the first and second positions is provided with through holes at the first and second positions of the acidic water tank, while the inner surface of the tank is provided. A first rubber packing is abutted around the through hole of the above, so that one short pipe of a rigid vinyl chloride flange with a bidirectional hard vinyl chloride short pipe is inserted into the through hole and protrudes outside the tank. The flange portion of the polyvinyl chloride flange with the short pipe is brought into contact with the first rubber packing, and the second rubber packing and the rigid vinyl flange are overlapped on the short pipe so as to project outward. The tank may be fitted and overlapped to abut around the through hole on the outer surface of the tank, and the respective abutting portions may be tightened with resin-coated bolts and nuts through the tank wall. Apply watertight piping to acidic water at three locations A through hole is provided at a third position of the tank for acidic water, and a third rubber packing is abutted around the through hole on the inner surface of the tank, and a hard vinyl chloride short tube for fitting is provided. The donut-shaped hard vinyl chloride donut-shaped thin plate with the short pipe is inserted into the through hole so that the short pipe for fitting into the doughnut-shaped thin sheet made of hard vinyl chloride is inserted into the through hole and protrudes outside the tank. A third rubber packing abuts on the other hand, and a fourth rubber packing and an outer fitting short pipe for a hard vinyl chloride flange with a hard vinyl chloride short pipe for outer fitting project to the inner fitting short pipe so as to protrude outward. The flange portion of the rigid vinyl chloride flange with the short tube for external fitting is overlapped with the fourth rubber packing and abuts around the through hole on the outer surface of the tank, and each abutting portion is attached to the tank wall. Use resin-coated bolts and nuts Those may be to Tightened Te.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIGS. FIG. 1 is a perspective view showing a first embodiment of a unit panel with a four-circle flange used in the present invention, and FIG. 2 is a perspective view showing a second embodiment of the same. FIG. 3 is a perspective view showing a first embodiment of the acidic water tank of the present invention, and FIG. 4 is a sectional view taken along line AA of FIG. 5 is an enlarged view of a section (B) in FIG. 4, FIG. 6 is an enlarged view of a section (C) in FIG. 4, and FIG. 7 is an enlarged view of a section (D) in FIG. 8 is an enlarged view of the section (E) in FIG. 4, FIG. 9 is an enlarged view of the section (F) in FIG. 4, and FIG. 10 is an enlarged view of the section (G) in FIG. is there.
FIG. 11 is a perspective view showing a third embodiment of a unit panel with a four-circle flange used in the present invention, and FIG. 12 is a perspective view showing a fourth embodiment of the same. FIG. 13 is a perspective view showing a second embodiment of the tank for acidic water of the present invention, and FIG.
4 is a sectional view taken along line HH of FIG.

FIG. 1 (a) is a perspective view of a first embodiment of a rigid PVC-coated unit panel used for the side wall and the bottom wall of the tank for acidic water of the present invention, in which the rigid PVC-coated surface is shown upward, FIG. 1 (B) is a perspective view showing the covering surface downward. The size of the rigid PVC-coated unit panel 1A is about 1 m square, and the unit panel 11 made of FRP, which is a base of the unit panel, is composed of a wall surface 12 and a four-peripheral flange 13, and a bolt hole 14 is provided in the four-peripheral flange 13. . The FRP unit panel 11 is provided with a hard PVC coating 15A. The hard PVC coating 15A is formed by vacuum forming a hard vinyl chloride plate having a thickness of about 1 to 4 mm, and is a shallow box-shaped body having a bottom 151 and a depth 152A.
2A extends to the inside of the bolt hole 14 of the four-circle flange 13. In such a rigid PVC-coated unit panel 1A, it is not necessary to form a bolt hole in the depth portion 152A, and the operation is simplified.

FRP unit panel 11 and hard PVC coating 1
Since the permanent fixing with 5A is performed by bolting the four circumferential flanges 13 together, the rigid PVC coated unit panel 1A shown in FIG.
Then, the temporary fixing between the FRP unit panel 11 and the hard PVC coating 15A may be performed using a double-sided adhesive tape (not shown). Further, the temporary fixing is not limited to this, and may be through an adhesive (not shown) that is appropriately scattered and applied, or may be another simple method. This temporary fixing method is the same as that of FIG. 2 described below, so that the description of FIG. 2 will be omitted.

FIG. 2 (a) is a perspective view of a second embodiment of the rigid PVC coated unit panel used for the side wall and the bottom wall of the tank for acidic water of the present invention, with the hard PVC coated surface facing upward, FIG. 2B is a perspective view showing the covering surface downward. The size of the rigid PVC-coated unit panel 1B is about 1 m square, and the FRP unit panel 11, which is a base portion thereof, includes a wall surface 12 and a four-circle flange 13, and a bolt hole 14 is provided in the four-circle flange 13. . The FRP unit panel 11 is provided with a hard PVC coating 15B. The hard PVC coating 15B is formed by vacuum forming a hard vinyl chloride plate having a thickness of about 1 to 4 mm, and is a shallow box-like body having a bottom 151 and a depth 152B.
2B extends over the entire area of the four-circumferential flange 13. Therefore, it differs from FIG. 1 in that a bolt hole 16B corresponding to the bolt hole 14 of the FRP unit panel 11 needs to be formed through the hard PVC coating 15B. The same parts are given the same numbers as in FIG.

[0011] In addition, there is a rigid PVC coated unit panel having a size of about 0.5 m x 1 m. For example volume of about 1m square ones and about 0.5m × 1m described above and is used together in the essential tank used ones of a by 0.5m wide and about 1.5 m ³ and 2.5 m ³ like You.

FIG. 3 is a perspective view showing a first embodiment of the tank for acidic water of the present invention. T is a tank for acidic water.
TA is a side wall, and two rigid PVC-coated unit panels 1A are connected to each other.
Are provided in opposition to each other. TB is another side wall and is composed of one rigid PVC-coated unit panel 1A, and a pair of side walls TB are provided facing each other in the entire tank T for acidic water. TC is a bottom wall and is a rigid PVC coated unit panel 1A
Are connected. TD is a ceiling wall, and the ceiling unit panel TD1 and the manhole unit panel TD2 are connected. 1G is a manhole cover. In the above configuration, the acidic water tank T is a tank having a height of about 1 m, side wall lengths of about 2 m and about 1 m, respectively, and a volume of about 2 m ³ .

In the present embodiment, the rigid PVC-coated unit panel 1A is used for the side wall and the bottom wall. However, the present invention is not limited to this. The rigid PVC-coated unit panel 1B shown in FIG. May be a rigid PVC coated unit panel. If you want to use a tank with a volume of about 1m ³ ,
A volume of about 1 m ³ on the side where the unit panel TD1 for ceiling is provided is removed from the tank T for acidic water with a volume of about 2 m ³ , and only a volume of about 1 m ³ on the side of the unit panel TD2 for manholes is used. do it.

The side wall TA and the side wall TB of the tank for acidic water shown in FIG. 3 have bases of respective vertical flanges abutting at four corners, and the outer surface of each flange is provided with a plurality of fixing brackets (not shown). ) Is fixed.

The bottom wall TC has a through hole 21 and a through hole 23, and the manhole unit panel TD2 has a through hole 2 and a through hole 23.
5 are provided. An overflow pipe J made of a hard PVC pipe is connected to the through hole 21, a drain pipe K made of a hard PVC pipe is connected to the through hole 23, and a hard PVC pipe is connected to the through hole 25. Water supply pipe L is connected. In FIG. 3, the details of the through holes 21, 23, and 25 are omitted.

FIG. 4 is a sectional view taken along line AA of FIG. FIG.
In the tank T for acidic water, the right and left ends of the tank T have a pair of side walls TB and TB each having a pair of rigid PVC-coated unit panels 1A, the lower end has a bottom wall TC connecting two rigid PVC-coated unit panels 1A, and an upper end. And a ceiling wall TD in which a ceiling unit panel TD1 and a manhole unit panel TD2 are connected.
Further, an overflow pipe J and a drain pipe K are connected to the bottom wall TC, and a water supply pipe L is connected to the manhole unit panel TD2.

Here, as described above, the rigid PVC-coated unit panel 1A shown in FIG. 1 is used for the side wall TB and the bottom wall TC, so that the FRP unit panel 11 is provided on the outer surface in cross section.
Are arranged, and a hard PVC coating 15A is arranged on the inner surface. The unit panel TD1 for ceiling has a unit panel 15D made of FRP on the outer surface in cross section, and a lined corrosion-resistant resin 11D on the inner surface. The unit panel TD2 for manholes has a unit panel 15E made of FRP on the outer surface in cross section and a lined corrosion-resistant resin 11D on the inner surface. Unit panel TD for manhole
The manhole inner cover 1F in which the corrosion-resistant resin 11D is lined on the inner surface of the manhole inner cover 15F made of FRP is placed on the short cylindrical manhole MH provided in 2, and the FR is further placed thereon.
The P manhole cover 1G is covered.

In FIG. 4, part (B) is a connecting part between the side wall TB and the bottom wall TC, part (C) is a connecting part between the bottom walls TC, and part (D) is a part connecting the side wall TB and the ceiling wall. The connection part with the TD, and the part (E) is a connection part between the ceiling unit panel TD1 and the manhole unit panel TD2, that is, a connection part between the ceiling walls TD.

FIG. 5 is an enlarged view of part (B) of FIG. In FIG. 5, the connection between the side wall TB and the bottom wall TC is made by the hard PVC coating 15 of the hard PVC coated unit panel 1A as the side wall TB.
The depth 152A of the hard PVC coating 15A of the hard PVC coating unit panel 1A as the bottom wall TC is in contact with the bottom 151 of A through the EPDM packing 160a, and the depth 152A of the bottom wall TC is Since it is up to the inside of the bolt hole 14c of the flange 13c of the bottom wall TC,
In order to evenly contact the flange 13c, a PVC foam packing 16a is inserted outside the bolt hole 14c, and the side wall TB and the flange 13c of the bottom wall TC are bolted.
Tightened by nuts 17a, 17b.

FIG. 6 is an enlarged view of part (C) of FIG. In FIG. 6, the connection between the bottom walls TC is such that the depth portions 152A of the hard PVC coating 15A of the hard PVC coating unit panel 1A as the bottom wall TC are in contact with each other via the EPDM packing 160b. Each said depth part 152
A is up to the inside of the bolt hole 14c of the flange 13c of the bottom wall TC, so that a PVC foam packing 16a, 16a is inserted outside the bolt hole 14c in order to evenly contact the flanges 13c with each other. The flanges 13c of the bottom wall TC are fastened to each other by bolts and nuts 17a and 17b.

The connection between the side walls TA (shown in FIG. 3) not shown in FIG. 4 is performed in the same manner as in FIG.

Assuming that the rigid PVC-coated unit panel 1B shown in FIG. 2 is used instead of the rigid PVC-coated unit panel 1A, the depth 152B of the rigid PVC coating 15B covers the entire surface of the flange 13c. The PVC foam packing 16a and the PVC foam packing 16b, 1 shown in FIG.
6b becomes unnecessary and a side wall TA (not shown) (FIG. 3)
Similarly, in the connection between them, a uniform PVC foam packing for contact is not required.

FIG. 7 is an enlarged view of part (D) of FIG. In FIG. 7, the connection between the side wall TB and the ceiling wall TD is the side wall TB.
PVC coating 1 of rigid PVC coating unit panel 1A as a unit
5A bottom portion 151 and FRP unit panel 15D of ceiling unit panel TD1 as ceiling wall TD (or FRP unit panel 15E of manhole unit panel TD2).
And a flange 13d (or 13e) of the ceiling resin TD via a PVC foam packing 160c, and these contact portions are lined with the inner surface of the ceiling wall TD.
They are tightly connected together with polyacetal-coated bolts and nuts 17e and 17f with D interposed therebetween.

FIG. 8 is an enlarged view of part (E) of FIG. In FIG. 8, the connection between the ceiling unit panel TD1 and the manhole unit panel TD2, that is, the connection between the ceiling walls TD,
Flange 13d of FRP unit panel 15D of ceiling unit panel TD1 and FR of manhole unit panel TD2.
The flange 13e of the unit panel 15E made of P is abutted through a PVC foam packing 160d, and the abutting portions are lined with the inner surfaces of the unit panel TD1 for the ceiling and the unit panel TD2 for the manhole. Resin 11
D and 11D are also clamped together with polyacetal covered bolts and nuts 17e and 17f.

FIG. 9 is an enlarged view of part (F) of FIG. A method of providing the overflow pipe J on the bottom wall TC of the acidic water tank will be described with reference to FIG. The bottom wall TC is the rigid PVC-coated unit panel 1A shown in FIG. 1, the outer surface is the wall surface 12 of the FRP unit panel, and the inner surface is the bottom 151 of the hard PVC coating. First, a through hole 21 is formed in the bottom wall TC. And 2
EPDM packings 212 and 213 and a bidirectional short pipe flange 211 obtained by welding a hard vinyl chloride short pipe 211b extending in both directions to a hard vinyl chloride flange 211a.
And one vinyl chloride flange 214 are prepared.

Around the through hole 21 on the inner surface of the acidic water tank, an EPDM packing 212 and a rigid polyvinyl chloride flange 2 are provided.
11a and one of the two-way short tubes 211b through the through holes 21.
Into contact with each other so as to protrude outside
An EPDM packing 213 and a rigid polyvinyl chloride flange 214 are abutted around the through hole 21 on the outer surface of the tank so as to be externally fitted to the protruding short pipe, and the respective abutting portions are the rigid PVC coated unit panel. 1A through the polyacetal-coated bolt / nut 216a, 217a (216
b, 217b).

In the water-tight structure as described above, the vinyl chloride socket 219 is attached to the tip of the short pipe inside the acidic water tank among the bidirectional rigid vinyl chloride short pipes 211b.
Is connected to a rigid vinyl chloride pipe 221 with a trumpet-like body (not shown) via a cable, and a vinyl chloride pipe 220 is connected via a vinyl chloride socket 218 to the tip of a short pipe protruding outside the tank for acidic water. If it does, it becomes overflow pipe J.

The connection of the water supply pipe L shown in FIG. 4 differs from that of FIG. 9 in that a through hole 25 is provided in the manhole unit panel TD2 and that FIG. 9 is used upside down. Others are the same except for the difference. Therefore the water pipe L
For, the description using the enlarged view is omitted.

FIG. 10 is an enlarged view of part (G) of FIG.
How to provide the drain pipe K on the bottom wall TC of the acidic water tank will be described with reference to FIG. The bottom wall TC is the rigid PVC-coated unit panel 1A shown in FIG. 1, the outer surface of which is the wall surface 12 of the FRP unit panel, and the inner surface thereof is the bottom 15 of the rigid PVC coating.
It is one. First, a through hole 23 is formed in the bottom wall TC. Then, two EPDM packings 232 and 233, and a donut-shaped thin plate 231 with a short pipe for internal fitting formed of a donut-shaped thin plate 231a made of hard vinyl chloride to which a short vinyl chloride pipe 231b for internal fitting is welded, One flange 234 with a short pipe for external fitting comprising a hard vinyl chloride flange 234a with a short vinyl chloride pipe for fitting 234b is prepared.

An EPDM packing 232 and the donut-shaped thin plate 231 are provided around the through hole 23 on the inner surface of the acidic water tank.
a and the EPDM packing 233 around the through-hole 23 on the outer surface of the tank.
And the hard vinyl chloride flange 234a and the hard vinyl chloride short pipe 234b for external fitting and the short pipe 231b for internal fitting.
And are abutted on each other so as to be externally fitted to the outer surface of the unit, and the respective abutting portions are connected to the polyacetal-coated bolts and nuts 236a and 237a (2
36b, 237b).

As described above, in a watertight structure,
A hard vinyl chloride tube 2 is provided on the inner surface of the external fitting short tube 234b.
If the connection 40 is made, a drain pipe K is obtained. The hard vinyl chloride donut-shaped thin plate 231a is preferably as thin as possible in order to enhance the drainage effect, and in this embodiment, a 2 mm thick one is used.

Next, FIG. 11 shows a third embodiment of a rigid PVC coated unit panel (hereinafter referred to as a coated unit panel) used in the acidic water tank of the present invention, and FIG. 12 shows a fourth embodiment of the same. Each (a) faces upwards, (b)
FIG. 2 is a perspective view showing a covering surface downward.

The covering unit panel 1C of FIG. 11 has the same structure as the covering unit panel 1A shown in FIG. 1, and the covering unit panel 1D of FIG. 12 has the same structure as the covering unit panel 1B shown in FIG. The difference is that the coating unit panels 1A and 1B
In contrast to the above, the coated unit panels 1C and 1D have an elongated shape of about 0.5m × 2m while the coated unit panels 1C and 1D are used only for the side walls, whereas the coated unit panels 1C and 1D are approximately 1m square. is there. Therefore, detailed description is omitted.

FIG. 13 is a perspective view showing a second embodiment of the acidic water tank according to the present invention, and FIG. 14 is a sectional view taken along line HH of FIG.

The tank Tx for acidic water shown in FIGS.
Has basically the same structure as the acidic water tank T shown in FIGS. The feature of the acidic water tank Tx is that four coating unit panels 1C are connected to one side wall TAx, and two coating unit panels 1C are connected to the other side wall TBx. Therefore, the width of the side wall TAx is about 2 m, the width of the side wall TBx is about 1 m, and the height is about 2 m. The acidic water tank Tx has the same projected area of about 2 m × 1 m as that of the acidic water tank T, but the height of the acidic water tank Tx is about 2 m, twice that of the acidic water tank T. Therefore, the capacity of the acidic water tank Tx is twice as large as that of the acidic water tank T. As the entire acidic water tank Tx, a pair of side walls TAx and side walls TBx are provided to face each other. Further, the bottom wall and the ceiling wall of the acidic water tank Tx and the acidic water tank T have the same specifications, and the ceiling wall is formed by connecting the manhole unit panel and the ceiling unit panel.

Although the coating unit panel 1C is used on the side wall of the acidic water tank Tx, the present invention is not limited to this, and the coating unit panel 1D may be used. When the volume is to be halved, FIG.
The volume on the side where the unit panel for ceiling is provided may be removed from the acidic water tank Tx, and only the volume on the side of the unit panel for manhole may be enclosed and used.

The mounting procedure of the overflow pipe, drain pipe and water supply pipe of the acidic water tank Tx is the same as that of the above-described acidic water tank T, so that the detailed description including the processing procedure of the through holes and the like is omitted. I do.

In the whole description above, the size of the water contact surface of the coated unit panel is about 1 m square, about 0.5 m × 1 m and about 0.5 m × 2 m, but is not limited thereto. Instead, one having a size appropriately selected as needed can be used.

[0039]

As described above, according to the present invention, it is possible to provide an acid water tank capable of securing acid resistance and water pressure resistance, and to provide an acid water tank which can be easily constructed at a construction site with a short construction period. It has the effect of being able to.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of a unit panel with a four-circle flange used in the present invention.

FIG. 2 is a perspective view showing a second embodiment in the same manner.

FIG. 3 is a perspective view showing an embodiment of an acidic water tank according to the present invention.

FIG. 4 is a sectional view taken along line AA of FIG. 3;

FIG. 5 is an enlarged view of a section (B) of FIG. 4;

FIG. 6 is an enlarged view of a section (C) of FIG. 4;

FIG. 7 is an enlarged view of a section (D) of FIG. 4;

FIG. 8 is an enlarged view of a section (E) of FIG. 4;

FIG. 9 is an enlarged view of a section (F) of FIG. 4;

FIG. 10 is an enlarged view of a section (G) of FIG. 4;

FIG. 11 is a perspective view showing a third embodiment of a unit panel with a four-circle flange used in the present invention.

FIG. 12 is a perspective view showing a fourth embodiment in the same manner.

FIG. 13 is a perspective view showing a second embodiment of the acidic water tank of the present invention.

FIG. 14 is a sectional view taken along line HH of FIG. 13;

[Explanation of symbols]

 1A, 1B, 1C, 1D Hard PVC coating unit panel 15A, 15B Hard PVC coating 151 Bottom 152A, 152B Depth 11 FRP unit panel T, Tx Acid water tank TA, TB, TAx, TBx Side wall TC Bottom wall TD Ceiling Wall TD1 Unit panel for ceiling TD2 Unit panel for manhole 21, 22, 23 Through hole J Flood pipe K Drain pipe L Water pipe 211 Flange with two-way short pipe 212, 213, 232, 233 EPDM packing 214 Hard vinyl chloride flange 231 Short Donut-shaped thin plate with tube 234 Flange with short tube

Claims (10)

[Claims] 1. A tank made of a unit panel with a four-circle flange, wherein a side wall and a bottom wall are made of a rigid vinyl chloride plate with a contact area between an inner wall surface of the FRP unit panel with a four-circle flange and flanges. A tank for acidic water, characterized in that it is a unit panel with a four-circle flange covered with a shape. 2. The acidic water tank according to claim 1, wherein the shallow box-like body is formed by vacuum forming. 3. The abutment area between the flanges is an inner area of a bolt hole of a four-flange flange.
The tank for acidic water as described. 4. The acidic water tank according to claim 1, wherein the contact area between the flanges is the entire area of the four-circumferential flange. 5. A tank formed by combining flanges of a unit panel with a four-circle flange and a manhole panel with a four-circle flange, wherein a side wall and a bottom wall abut the inner wall surface of the FRP unit panel with a four-circle flange and the flanges. And a unit panel with a four-circle flange covered with a shallow box made of a rigid polyvinyl chloride plate.
Alternatively, the inner wall of the FRP unit panel with the corrosion-resistant resin lined on the inner surface of the FRP unit panel with the four-circle flange, and the inner cover with the corrosion-resistant resin lined on the inner surface of the FRP lid with the manhole cover An acidic water tank having a double structure with an outer lid, wherein water-tight piping is applied to acidic water at first, second, and third positions. 6. The acidic water tank according to claim 5, wherein the shallow box-shaped body is formed by vacuum forming. 7. The abutment area between the flanges is an area inside the bolt hole of the four-flange flange.
The tank for acidic water as described. 8. The acidic water tank according to claim 5, wherein the contact area between the flanges is the entire area of the four-circle flange. 9. Providing water-tight piping to the acidic water at the first and second positions, providing a through hole at the first and second positions of the tank for acidic water, while providing an inner surface of the tank. A first rubber packing is abutted around the through hole of the above, so that one short pipe of a rigid vinyl chloride flange with a bidirectional hard vinyl chloride short pipe is inserted into the through hole and protrudes outside the tank. The flange portion of the polyvinyl chloride flange with the short pipe is brought into contact with the first rubber packing, and the second rubber packing and the rigid vinyl flange are overlapped on the short pipe so as to project outward. The tank is fitted and overlapped to abut around the through hole on the outer surface of the tank, and the respective abutting portions are tightened with resin-coated bolts and nuts through the tank wall. An acidic water tank according to claim 5. 10. A watertight pipe for acidic water at a third position, wherein a through hole is provided at a third position of the tank for acidic water, while a through hole is provided on an inner surface of the tank around the through hole. A third rubber packing is abutted, and the short pipe for fitting is formed by inserting the short pipe for fitting into a doughnut-shaped thin plate made of hard vinyl chloride with a short vinyl pipe for fitting into the through hole so as to protrude to the outside of the tank. The donut-shaped thin plate made of the rigid vinyl chloride donut-shaped thin plate with the short pipe abuts on the third rubber packing, and the outer fitting of the fourth rubber packing with the rigid vinyl chloride flange with the hard vinyl chloride short pipe for external fitting. An outer surface of the tank is formed by externally fitting a short pipe for internal fitting which is formed so as to protrude outwardly and overlapping a flange portion of the rigid polyvinyl chloride flange with the short pipe for external fitting with the fourth acid-resistant packing. Contact around the through hole of each Acidic water tank of claim 5, wherein a is to Tightened with bolts and nuts of the resin-coated through the tank wall.