JP2006083434A - Electric protection method and electric protection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably, electrolytically protect a water-distribution vertical pipe in which a fire hydrant is installed, with a simple configuration. <P>SOLUTION: This electric protection apparatus is a cathodic protection apparatus for electrolytically protecting the inside of the water-distribution vertical pipe 5 in which the fire hydrant 8 is installed; and comprises a two-chamber type lead storage battery 4 as an external power source, a bar-type electrode body 1 composing an anode, and an insulating material that has a plurality of openings of which the open area ratio is set, and that covers the bar-type electrode body 1. The open area ratio of the openings is adjusted such that a desired protection current can be obtained. The bar-type electrode body 1 is inserted from a short pipe or the underground hydrant 8, which is installed in the upper part of the water-distribution vertical pipe 5. Not only the insertion part 11 of the bar-type electrode body 1, but also the insertion part 13 of an endoscope camera 12 is also installed in the short pipe or the underground hydrant 8. Accordingly, the inside of the water-distribution vertical pipe 5 can be observed through the endoscope camera 12. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an anticorrosion method and an anticorrosion device, and more particularly to an anticorrosion method and an anticorrosion device for preventing rust from being generated in a vertical pipe of a water pipe where a fire hydrant is installed.

  The vertical pipe of the water pipe where the fire hydrant is installed is prone to air accumulation and rust humps are likely to occur. Such rust humps not only deteriorate the water quality, but also have a risk of adversely affecting fire fighting activities by deteriorating water. However, conventionally, there is no known anticorrosion technique for this water distribution vertical pipe.

  On the other hand, the anti-corrosion technique has been conventionally known. In general anticorrosion, the object of corrosion protection is not an anode (anode) but a cathode (cathode). And as an application system of cathodic protection, there are an external power supply system and a galvanic anode system (sacrificial anode system). The external power source method uses a DC power source, and the galvanic anode method is a method in which a base metal is connected to the object to be protected and a corrosion preventing current is caused to flow by utilizing a potential difference between the two.

When considering the anti-corrosion in the water distribution vertical pipe where the fire hydrant is installed, there are various problems to be solved. First, when the galvanic anode method is adopted, since the water pipe in which the fire hydrant is installed is also used as the water supply, elution of metal ions (Al ³⁺ , Mg ²⁺ , Zn ²⁺ ) becomes a problem.

  On the other hand, when the external power supply method is adopted, securing the power supply becomes a problem. In a normal external power supply system, a commercial power supply (100 V AC) is transformed to a desired voltage and then rectified (converted from AC to DC) to obtain a desired DC power supply. However, since the water distribution vertical pipe where the fire hydrant is installed is usually in the basement of the road, securing a commercial power source becomes a problem.

  If it is an external power supply system and a commercial power supply (100 V AC) cannot be used, it is conceivable to supply power from various batteries. However, when a solar cell is used, the configuration is complicated and power can be generated only during the daytime, and the generated voltage does not always match the voltage required for anticorrosion, and there is a possibility that reliable and stable electrocorrosion cannot be achieved. is there. Further, when using a manganese dry battery, an alkaline dry battery or the like, the shape is limited to single, single, single or three, and it is necessary to prepare a container for storing a large number of them, which is not practical. For example, in order to prevent corrosion of a 1 m long vertical tube for one year, a single dry battery requires about 100 pieces. The fire hydrant is mostly in the basement and is housed in a small BOX, and in order to store the power supply in this, it is necessary to have a compact and highly flexible shape.

  The present invention has been made in view of the above circumstances, and its main purpose is to achieve stable anticorrosion with a simple configuration, particularly to reliably prevent corrosion in a water distribution vertical pipe where a fire hydrant is installed. The object is to provide a suitable cathodic protection method and cathodic protection device.

  The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 is a cathodic protection method using an external power supply system, and uses an external power supply that maintains a predetermined voltage to adjust the anticorrosion current. Is an anticorrosion method characterized by adjusting the opening of the insulating material covering the anode.

  The invention according to claim 2 is a cathodic protection method for electrically protecting the inside of a water distribution vertical pipe in which a fire hydrant is installed, wherein a two-chamber lead storage battery is used as an external power source, and an insulating material having a plurality of openings as an anode The rod-shaped electrode body covered with the above-described method is used, and the rod-shaped electrode body in which the aperture ratio of the opening is adjusted so as to obtain a desired corrosion-proof current is installed inside the vertical pipe.

  According to a third aspect of the present invention, there is provided an external power source type cathodic protection device, an external power source that maintains a predetermined voltage, an electrode body that constitutes an anode, and an insulation that covers the electrode body and adjusts an aperture ratio. It is an anticorrosion apparatus characterized by including a material.

  The invention according to claim 4 is a cathodic protection device that catalyzes the inside of a water distribution vertical pipe in which a fire hydrant is installed, and includes a two-chamber lead storage battery as an external power source, a rod-shaped electrode body that constitutes an anode, And an insulating material that covers the rod-shaped electrode body with an opening ratio set.

  Furthermore, in addition to the constituent features of claim 4, the invention according to claim 5 inserts the rod-shaped electrode body and the endoscope camera into a short pipe or an underground fire hydrant provided at the upper part of the water distribution vertical pipe. The rod-shaped electrode body and the endoscopic camera are inserted into the water distribution vertical pipe from the insertion portion.

  According to the cathodic protection method and the cathodic protection device of the present invention, stable cathodic protection can be achieved with a simple configuration. In particular, the anticorrosion in the water distribution vertical pipe where the fire hydrant is installed can be realized with a simple configuration.

  Next, an embodiment of the present invention will be described. The cathodic protection method and the cathodic protection device of the present invention are preferably applied to a vertical pipe portion of a water supply water pipe. Therefore, here, an example in which the present invention is applied to this water distribution vertical pipe will be described. A fire hydrant is installed in the upper part of the water distribution pipe through a repair valve.

  The cathodic protection device of the present embodiment includes a rod-shaped electrode body inserted into a water distribution vertical pipe and an external power supply device for generating a corrosive protection current as main parts. Then, the water distribution vertical pipe is electrically anticorrosive by energizing the rod-shaped electrode body as an anode and the water distribution vertical pipe as a cathode by an external power supply device. The conductive rod-shaped electrode body is covered with an insulating material, and a plurality of openings are formed in the insulating material. Therefore, the rod-shaped electrode body is exposed to the outside at each opening, and an anticorrosion current is passed between the opening and the water distribution vertical pipe to electrically prevent the water distribution vertical pipe. In addition, the rod-shaped electrode body is inserted and installed from a fire hydrant or a short pipe installed at the upper part of the water distribution vertical pipe to the lower part of the water distribution vertical pipe in a watertight state with respect to the outside.

  In a water distribution vertical pipe where a fire hydrant is installed, it is difficult to secure a commercial power supply (100 V AC), and therefore, in this embodiment, a lead storage battery is used as an external power supply. In particular, a two-chamber lead storage battery is preferably used for the following reason. Since the voltage of the lead storage battery is 2 V per room (one cell), the voltage of the two-chamber lead storage battery is 4 V.

The reason for using the two-chamber lead storage battery is as follows. That is, first, the diameter of the fire hydrant is limited to 75 mm or 100 mm. For this reason, the distance between the electrode (anode) and the water distribution vertical pipe wall (cathode) is also limited. And the electrical conductivity of Japanese waterworks is about 50-300 micro S / cm, and 50 mA / m < ² > (cathode area) is standard as an anticorrosion required electric current. Considering these circumstances (conductivity, distance between cathode and anode, current necessary for anticorrosion), approximately 3 to 4 V is required. Therefore, when using lead-acid batteries as an external power source in the cathodic protection of water distribution vertical pipes, the required voltage is insufficient in one room (2V), the voltage is unnecessarily high in three rooms (6V), and power is wasted. .

  By the way, in a conventional general external power source type anticorrosion method, the voltage should be adjusted in order to obtain a required anticorrosion current. That is, in the past, a commercial power supply (100V AC) was used as an external power supply, transformed to a desired voltage, and then rectified (converted from AC to DC) to obtain a desired DC voltage. However, when an external power supply that maintains a predetermined voltage (here, 4 V) is used as in this embodiment, there is a problem of how to adjust the anticorrosion current.

  In the present invention, the anticorrosion current can be adjusted while maintaining the applied voltage constant rather than the voltage adjustment as before. That is, this is because the rod-shaped electrode body constituting the anode is covered with an insulating material, and the openings (the size, number, ratio, etc.) formed in the insulating material are changed. In this embodiment, in order to maintain the physical mechanical strength, a rod-shaped metal material having a diameter of 2 to 5 mm is used as the anode, and the number of small holes formed in the insulating material covering the anode is changed to change the anode area. The (corrosion prevention current) is controlled by changing (the area of the small hole). The reason why such control is possible is that the oxygen overvoltage of the anode changes depending on the anode current density.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1: is a schematic enlarged view which shows the anode of the cathodic protection apparatus of this invention, (A) is a front view, (B) is the XX sectional drawing. As shown in this figure, the anode of the present embodiment is composed of an elongated conductive rod-shaped electrode body 1 whose outer surface is covered with an insulating coating (insulating material) 2. In this embodiment, an elongated cylindrical heat-shrinkable tube is used as the insulating material 2, and after forming a large number of appropriate small holes 3 (3a, 3b) in advance, it is fitted into the rod-shaped electrode body 1 and heated to shrink, The rod-shaped electrode body 1 is brought into close contact with and integrated.

  In the state in which the insulating material 2 is attached to the rod-shaped electrode body 1, the outer peripheral surface and the distal end surface of the rod-shaped electrode body 1 are covered with the insulating material 2, but the base end portion 1 a of the rod-shaped electrode body 1 is exposed from the insulating material 2. The And such an anode is electrically connected to the external power supply 4 (refer FIG. 2) through the said exposed part 1a of the rod-shaped electrode body 1. FIG. The small holes 3 are formed in the insulating material 2 made of a heat-shrinkable tube by penetrating the small holes 3 with a punch in a state in which the circular cross section is flattened in advance before covering the rod-shaped electrode body 1. Yes.

The material and size of the rod-shaped electrode body 1 are appropriately set. The rod-shaped electrode body 1 of the present embodiment is made of, for example, a titanium rod having a diameter of 4 mm, and the surface thereof is coated with, for example, iridium oxide (IrO ₂ ) having a thickness of 0.3 μm as a main component. . The length of the rod-shaped electrode body 1 is preferably set to a length that extends to the bottom of the water distribution vertical pipe 5, that is, the water distribution pipe 6 below the vertical pipe 5 at the time of installation (see FIG. 4). As the insulating material 2 covering the rod-shaped electrode body 1, an appropriate one is adopted, but the insulating material 2 of the present embodiment employs a resin heat shrinkable tube having a thickness of 0.25 mm.

  By adjusting the aperture ratio of the small holes 3 formed in the insulating material 2, the exposed portion of the rod-shaped electrode body 1 can be adjusted, and the anticorrosion current can be adjusted. The aperture ratio to be used is determined in consideration of the conductivity of water at the location where the anticorrosion device is applied. In order to see the correlation between the electrical conductivity of the water and the insulation specifications, an experiment was conducted using an experimental apparatus as shown in FIG.

  In this experimental apparatus, a steel pipe (SGP pipe) 5 of 100A (inner diameter 105.3 mm) and length 0.95 m was used. The bottom of the steel pipe 5 is covered with a bottom plate 7 made of transparent vinyl chloride, and a concave hole 7a is formed at the center of the upper surface of the bottom plate 7. And the 4 mm diameter rod-shaped electrode body 1 mentioned above was inserted in this steel pipe 5, and the front-end | tip part (lower end part) was inserted and fixed to the said concave hole 7a. Further, in order to use the rod-shaped electrode body 1 as an anode and the steel tube 5 as a cathode, the base end portion 1a of the rod-shaped electrode body 1 is connected to the positive electrode (+) of the external power source (DC 4V) 4 and the negative electrode ( The steel pipe 5 was connected to-). In that state, the steel pipe 5 is filled with tap water and energized, and the anticorrosion current is measured. Here, experiments were conducted on waterworks in Iwaki City, Fukushima Prefecture and Kobe City, Hyogo Prefecture. The conductivity of tap water used in the experiment was 64 μS / cm for water in Iwaki City, 267 μS / cm for water in Kobe City, and 352 μS / cm water was also investigated.

  In the experiment, a plurality of rod-shaped electrode bodies 1 having different insulation specifications were created, and the anticorrosion current in each case was measured. The insulation specifications used in the experiment are the following [insulating material A] to [insulating material E].

[Insulating Material A] As shown in FIG. 1, an insulating material (compounds) in which 38 small holes 3 (3a, 3b) each having a length of 10 cm are formed in double rows on both the front and back sides of the rod-shaped electrode body 1, respectively. Column). Each small hole 3 has a diameter of 1.14 mm. Strictly speaking, each small hole 3 is somewhat large and there is an error in diameter measurement. In this case, the aperture ratio is calculated as follows. That is, the aperture ratio in this case is calculated as {(1.14 mm) ² × (π / 4) × 38 × 2 × 2} / {100 mm × 4 mm × π} = 0.123. In this case, the opening area per meter is 15.5 cm ² / m.

  [Insulating material B] An insulating material (single row) in which A is arranged in a single row. That is, an insulating material in which 38 small holes 3 each having a length of 10 cm are formed in a single row (only the small holes 3 a in FIG. 1) on both sides of the front surface and the back surface of the rod-shaped electrode body 1. In this case, the aperture ratio is ½ of A.

  [Insulating material C] Insulating material (single row 1/2) in which every other B hole is provided.

  [Insulating Material D] Insulating material (single row 1/8) in which the B holes are every eight holes.

  [Insulating Material E] An insulating material (single row 1/16) in which the B holes are one for every 16 holes.

As a result of the experiment, for example, in the case of the double row insulating material A, a current of 22 mA flowed to the water in Iwaki City. This is as a protective current density is a value said to be more fully corrosion than 50 mA / ^{m 2} to be 74mA / ^{m 2,} and the normally required. One week passed in this state, but no turbidity was observed in the internal water. On the other hand, as a comparative example, when left unpowered, some turbidity (red rust) was observed in one day. Further, after one week, red rust was thinly deposited on the bottom of the steel pipe 5.

FIG. 3 shows the experimental results in a log-log graph. In this figure, the vertical axis represents the measured anticorrosion current value (mA), and the horizontal axis represents the anode exposed area (cm ² / m) and the aperture ratio. From this figure, it can be seen that the greater the coating 2, the greater the anticorrosion current flows. Since the required anticorrosion current density is 50 mA / m ² , the effective aperture ratio for each tap water may be calculated by calculating back the aperture ratio at which the current value is obtained. In the experimental example, it was found that in Iwaki City, it is sufficient to form a single-row insulating material with 2/3 having holes and the remaining 1/3 without holes. As for Kobe city, it was found that in a single-row insulating material, 1/20 should be formed with holes and the remaining 19/20 without holes. In this way, the aperture ratio (number of small holes) may be changed in accordance with the conductivity of city water in each place so as to obtain an appropriate anticorrosion current density (about 50 mA / m ² ).

FIG. 4 is a view showing a use state of an embodiment of the cathodic protection device of the present invention, and a part thereof is shown in cross section.
The water distribution pipe 6 from the water purification plant or the water distribution station is provided with a fire hydrant 8 through a vertical pipe 5 made of a metal pipe (steel pipe, cast iron pipe) that branches vertically upward. The fire hydrant 8 is provided at the upper end of the vertical pipe 5 branched from the water distribution pipe 6 via a repair valve 9. The fire hydrant 8 and the repair valve 9 are accommodated in a box 10 buried underground. A water supply pipe (not shown) is connected and branched to the water distribution pipe 6 via a saddle water faucet, and water is supplied to each household via this water supply pipe.

  The fire hydrant 8 is an underground fire hydrant and is preferably provided with an exhaust valve or an air valve (with underground fire hydrant exhaust valve, underground air valve fire hydrant). Moreover, the thing with the built-in air valve is more preferable (underground air valve built-in fire hydrant). Furthermore, the underground fire hydrant 8 of the present embodiment is provided with an insertion portion 11 for the rod-shaped electrode body 1 and an insertion portion 13 for the endoscope camera 12 of the electric protection device. The insertion portions 11 and 13 are provided above the lower flange 8a of the fire hydrant 8 and below a sealing portion (not shown) formed by an on-off valve inside the fire hydrant 8. The lower flange 8a of the fire hydrant 8 is connected to the upper flange 9a of the repair valve 9 in a watertight state, and the lower flange 9b of the repair valve 9 is connected to the upper flange 5a of the vertical tube 5 in a watertight state.

  The insertion part 11 of the rod-shaped electrode body 1 is configured such that a packing (not shown) is accommodated and held in an opening that penetrates the valve box (outer wall) of the fire hydrant 8. Through this packing, the rod-shaped electrode body 1 is inserted into the fire hydrant 8 and thus into the water distribution vertical pipe 5 while being bent. This packing is in a state in which the outer peripheral portion of the rod-shaped electrode body 1 with the insulating material 2 is fastened, but the rod-shaped electrode body 1 can be advanced and retracted. Therefore, the rod-shaped electrode body 1 can be sent and installed in the water distribution vertical pipe 5 from the outside to the inside of the fire hydrant 8 while preventing water leakage from the water distribution pipe 6.

  By the way, the rod-shaped electrode body 1 can be the same as that used in the experiment, that is, the iridium oxide-coated titanium rod 1 covered with the insulating material (heat shrinkable tube) 2. And the small hole 3 is formed in the insulating material 2 which consists of a heat-shrinkable tube with the aperture ratio matched with the electrical conductivity of the water of an installation location. It is sufficient that the small hole 3 is formed at a place where the small electrode 3 is inserted into the water distribution vertical pipe 5 when the rod-shaped electrode body 1 is used. Further, in such a rod-shaped electrode body 1, the titanium rod 1 is connected to the positive electrode (+) of the two-chamber lead-acid battery 4 at the base end side, and the negative electrode (−) is connected to the fire hydrant 8 (or to it). It is connected to the repair valve 9 and the vertical pipe 5). Since the surface of the titanium rod 1 is covered with the insulating material 2, even if the rod-shaped electrode body 1 comes into contact with the inner surface of the vertical tube 5, there is no electrical conduction. In this way, the anticorrosion of the vertical pipe 5 is effectively achieved.

  The endoscope camera 12 is for observing the situation inside the vertical tube 5. A camera cable 12b having a camera body 12a at the distal end is wound around a drum 12c at the proximal end. The cable 12b can be fed out from the drum 12c, and conversely, the cable 12b can be wound around the drum 12c. Such an endoscope camera 12 is inserted into the fire hydrant 8 and thus into the water distribution vertical pipe 5 from the camera insertion port 13 provided in the fire hydrant 8.

  The camera insertion port 13 is composed of a pipe body branched from the valve box of the fire hydrant 8, and the tube end portion is an insertion tool attachment portion 13 a (see FIG. 5) to which the camera insertion tool 14 can be attached and detached. ing. Specifically, the insertion tool attachment portion 13a is formed on a flange or a screw portion. In addition, an opening / closing valve 13b (see FIG. 5) is provided in the central portion of the tubular body constituting the camera insertion port 13.

  On the other hand, the camera insertion tool 14 has a hollow box shape, and this hollow box is open to the distal end side which is a connection side to the insertion tool mounting portion 13. The hollow box 14 can accommodate the camera body 12a. The camera cable 12b is led out from the base end of the hollow box 14 through a packing. Therefore, in order to insert the camera 12 from the camera insertion port 13 of the fire hydrant 8 into the water distribution vertical pipe 5, first, the camera insertion tool 14 is connected to the insertion tool mounting portion 13a with the opening / closing valve 13b closed, and the opening / closing operation is performed. After opening the valve 13b, the camera body 12a can be inserted into the fire hydrant 8 and thus into the water distribution vertical pipe 5 by pushing the camera cable 12b.

  As described above, according to the configuration of the present embodiment, the camera 12 can be easily inserted with continuous water. Moreover, even in the installed state, the camera cable 12b is led out to the outside in a watertight state through the packing of the hollow box 14, so that there is no risk of water leaking outside the fire hydrant 8. Conversely, when removing the camera 12, the cable 12b is pulled to house the camera body 12a in the camera insertion tool (hollow box) 14, and then the on-off valve 13b is closed, and then the camera insertion tool 14 is connected to the fire hydrant 8 You can remove it. When the camera insertion tool 14 is not normally attached, the insertion tool attachment portion 13a may be covered.

  In this way, according to the present embodiment, by inserting the endoscope camera 12 into the water distribution vertical pipe 5, it is possible to easily check the status and cause of rust humps and red water in the pipe. In addition, the effect and verification of the anticorrosion device can be made, and the capacity and number of the lead storage batteries 4 or the opening ratio of the small holes 3 formed in the insulating material 2 of the rod-shaped electrode body 1 can be adjusted (the insertion of the rod-shaped electrode bodies 1 having different opening ratios). Can also be performed. Therefore, the life of the lead storage battery 4 can also be examined. Furthermore, it is possible to confirm whether the rod-shaped electrode body 1 is at a desired position.

  By the way, although FIG. 4 demonstrated the example which provided the insertion part 11 of the rod-shaped electrode body 1 and the insertion part 13 of the endoscope camera 12 in the fire hydrant 8, it installed in the upper part of the repair valve 9 as shown in FIG. The short tube 15 may be provided. The short pipe 15 has a cylindrical shape, and the lower flange 15a is connected to the upper flange 9a of the repair valve 9 in a watertight state. An outer peripheral surface of the short tube 15 is provided with an insertion portion 11 of the rod-shaped electrode body 1 and an insertion portion 13 of the endoscope camera 12 with the same configuration as in FIG. A fire hydrant 8 or the like is installed on the upper portion of the short tube 15 or a lid is formed.

  According to the cathodic protection device of the present embodiment described in detail above and the cathodic protection method using the same, the water distribution vertical pipe 5 can be effectively rustproofed. Moreover, a structure is also simplified by using a direct-current power supply for the anticorrosion apparatus used by direct current. Furthermore, the effect can be confirmed by enabling insertion of the endoscope camera 12. In addition, when installing the anticorrosion apparatus of a present Example, it is good to attach after removing the rust hump already adhering in the water distribution vertical pipe 5. FIG. In order to remove the rust humps in the vertical tube 5, a previously proposed rust hump removing device (Japanese Patent Application No. 2003-31643) can be used.

  In addition, the cathodic protection device and the cathodic protection method of the present invention are not limited to the configuration of the above embodiment, and can be changed as appropriate. For example, in the above embodiment, the rod-shaped electrode body 1 uses an iridium oxide-coated titanium rod covered with the heat shrinkable tube 2, but the anode surface is covered with an insulating material and the opening formed in the anode is formed. If it is the structure which obtains a desired anticorrosion current by adjusting the area of 3, it will not be restricted to the structure of the said Example. Moreover, although the said Example demonstrated the example used for the cathodic protection of the water distribution vertical pipe 5 in which the fire hydrant 8 was installed, it is applicable also to the cathodic protection of another location.

It is a schematic enlarged view which shows the anode of the cathodic protection apparatus of this invention, (A) is a front view, (B) is the XX sectional drawing. It is the schematic which shows the experimental apparatus of the Example of the cathodic protection apparatus of this invention. It is a figure which shows the experimental result by the apparatus of FIG. It is a figure which shows the use condition of one Example of the cathodic protection apparatus of this invention, and has shown it by making a part into a cross section. It is a figure which shows the modification of FIG.

Explanation of symbols

1 Rod-shaped electrode body 2 Insulation material (heat shrinkable tube)
3 openings (small holes)
4 External power supply (two-chamber lead acid battery)
5 Water Distribution Vertical Pipe 6 Water Distribution Pipe 8 Fire Hydrant 9 Repair Valve 11 Rod Electrode Insertion Port 12 Endoscope Camera 13 Camera Insertion Port 15 Short Pipe

Claims (5)

Cathodic protection method by external power supply method,
An anticorrosion method characterized by using an external power source that maintains a predetermined voltage and adjusting the anticorrosion current by adjusting an opening of an insulating material covering the anode. A cathodic protection method that catalyzes the inside of a water distribution pipe where a fire hydrant is installed,
A rod-shaped electrode using a two-chamber lead-acid battery as an external power source and a rod-shaped electrode body covered with an insulating material having a plurality of openings as an anode, and adjusting the opening ratio of the openings so as to obtain a desired anticorrosive current An anti-corrosion method characterized by installing a body inside the vertical pipe. Cathodic protection device with external power supply system,
An anticorrosion apparatus comprising: an external power source that maintains a predetermined voltage; an electrode body that constitutes an anode; and an insulating material that covers the electrode body and has an aperture ratio adjusted. A cathodic protection device that catalyzes the inside of a water distribution pipe where a fire hydrant is installed,
A two-chamber lead-acid battery as an external power source, a rod-shaped electrode body constituting an anode, and an insulating material having a plurality of openings and having an aperture ratio set to cover the rod-shaped electrode body An anti-corrosion device. In the short pipe or underground fire hydrant provided at the upper part of the water distribution vertical pipe, an insertion part of the rod-shaped electrode body and the endoscope camera is provided,
The cathodic protection device according to claim 4, wherein the rod-shaped electrode body and the endoscope camera are inserted into the water distribution vertical pipe from the insertion portion.

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