JP2010047814A - Current measurement method and current measurement device for sacrificial anode in electrically conductive liquid - Google Patents

Abstract

The present invention provides a current measuring method and a current measuring device for a sacrificial anode in a conductive liquid, which can measure a corrosion-proof current generated from the sacrificial anode during the implementation of the anti-corrosion without removing the sacrificial anode.
An insulating cover is installed so as to cover the sacrificial anode, and a current is applied between a counter electrode installed outside the cover and the metal structure, and potentials on the outside and inside of the cover are measured. In addition, the current value of the anticorrosion current is estimated from the potential outside the cover and the current value of the applied current when the potential difference between the outside of the cover and the inside of the cover is zero.
[Selection] Figure 2

Description

  The present invention relates to a current measuring method and a current measuring device for a corrosion-proof current flowing out from a sacrificial anode, which is installed to perform an anti-corrosion of a metal structure in a conductive liquid (for example, seawater) such as an offshore plant or ship. .

Marine structures such as marine plants and ships are surrounded by seawater and are in a severe corrosive environment. As a method for preventing the corrosion of such a metal structure in seawater, there is a method of performing anticorrosion. In electrocorrosion protection, steel materials in seawater and submarine soils are anticorrosive using an electrochemical technique. That is, by continuously flowing a direct current from the outside into the steel material to overcome the corrosion current that flows from the steel material to the electrolyte (seawater), the steel material is prevented from being ionized (corroded).
One of the anticorrosion methods is a technique called a galvanic anode method. The galvanic anode method uses the level of ionization tendency of the metal. Instead of iron ionizing (corrosion) that connects metals (Al, Zn, Mg, etc.) that have a higher ionization tendency than iron, These metals are ionized to prevent corrosion of steel materials. That is, the steel material to be anticorrosive is used as a cathode, the battery is completed by using a (base) metal having a higher ionization tendency than the steel material as a sacrificial anode, and the anticorrosion current is caused to flow by the potential difference between both electrodes.

  FIG. 6 is a diagram illustrating the cathodic protection of the metal structure 1 in contact with the conductive liquid 20 such as seawater by the galvanic anode method. Paint 2 is applied to the boundary between the metal structure 1 and the liquid 20. In order to prevent corrosion of the metal structure 1, a sacrificial anode 3 made of a (base) metal having a higher ionization tendency than the metal constituting the metal structure 1 (if the metal constituting the metal structure 1 is iron, the sacrificial anode 3 is sacrificed. The anode 3 is made of an aluminum alloy or the like.) Is installed by welding or the like on the part where the metal structure 1 contacts the liquid 20. The metal structure 1 and the sacrificial anode 3 are connected so as to be electrically conductive. Since the sacrificial anode 3 has a higher ionization tendency than the metal structure 1, the anticorrosion current flows in the direction indicated by the dotted arrow in FIG. 6, and the metal constituting the metal structure 1 is prevented from being ionized and corroded. .

If the anticorrosion current generated from the sacrificial anode can be measured quantitatively, it is effective because it is possible to predict the life of the sacrificial anode and grasp the deterioration state of the paint. Conventionally, a method of measuring the anticorrosion current generated by the sacrificial anode by measuring the voltage drop method by inserting a shunt resistor between the sacrificial anode and the structure and separating the core metal of the sacrificial anode from the structure. (For example, refer nonpatent literature 1).
FIG. 7 is a view showing a specific example of an apparatus for measuring the anticorrosion current flowing out from the sacrificial anode using a voltage drop method (see Patent Document 1). In the apparatus shown in FIG. 7, the thin groove 106 is fixed to the metal structure 101, and the grooved steel 106 and the cored bar 121 of the sacrificial anode 102 are fixed with an insulating bolt nut 141 via the electrical insulator 103. Further, the one anode core 121 and the grooved steel 106 are connected to the terminal 143 and the terminal 144 of the DC current measuring device 105, respectively. There is a shunt resistor in the DC current measuring device 105, and the core wire of the cable 107 is connected to both ends of the shunt resistor, and the cable 107 is led to the ground.
Material of Port Engineering Lab. 475 Electrocorrosion Investigation of Port Structures (Part 1) Port Technology Research Institute, Ministry of Transport Issued in March 1984 JP 2005-264286 A

As described above, a shunt resistor is inserted between the sacrificial anode and the metal structure, the core metal of the sacrificial anode is cut off from the metal structure, and the anticorrosion current generated from the sacrificial anode is measured by the voltage drop method. In this case, it takes a long time to cut off the sacrificial anode from the metal structure, and the work cost for it is high.
The present invention has been made for the above-mentioned circumstances, and an object of the present invention is to provide a sacrificial anode in a liquid that can measure a corrosion-proof current flowing out from the sacrificial anode during the implementation of the electro-corrosion without removing the sacrificial anode. An object of the present invention is to provide a current measuring method and a current measuring apparatus.

  The present invention relates to a method for measuring the current of the sacrificial anode in a galvanic anode method in which a sacrificial anode is installed on a metal structure in a conductive liquid. The object of the present invention is to provide insulation so as to cover the sacrificial anode. A cover having a cover, applying a current between the counter electrode installed on the outside of the cover and the metal structure, measuring the potential on the outside of the cover and on the inside of the cover, and measuring the potential on the outside of the cover. And the current value of the anticorrosion current is estimated from the current value of the applied current when the potential difference between the outside of the cover and the inside of the cover is zero.

The object of the present invention is that the current value when the potential difference is 0 is Ieq, the cover outside potential when the current value is 0 is V _out 0, and the cover outside potential when the potential difference is 0. Is V _out eq, and the natural potential of the metal structure is Vn, the current value Is of the anticorrosion current is
_{Is = (V out 0-Vn} ) Ieq / (V out eq-Vn)
Is effectively achieved by estimating by.

  The present invention relates to a method for measuring the current of the sacrificial anode in a galvanic anode method in which a sacrificial anode is installed on a metal structure in a conductive liquid. The object of the present invention is to provide insulation so as to cover the sacrificial anode. And when a potential difference between the outside of the cover and the inside of the cover is 0, a current is applied between the counter electrode 1 installed on the inside of the cover and the counter electrode 2 installed on the outside of the cover. This is achieved by setting the current value of the current to the current value of the anticorrosion current.

  The present invention relates to a current measuring device for the sacrificial anode in a galvanic anode method in which a sacrificial anode is installed on a metal structure in a conductive liquid, and the object of the present invention is to provide an insulation covering the sacrificial anode. Cover, a pair of reference electrodes installed inside and outside the cover, a counter electrode installed outside the cover, the counter electrode and the metal in a state where the cover covers the sacrificial anode A DC power source for applying a current between the structures, a voltage measuring means for measuring the potential of each reference electrode, and an applied current of the DC power source so that the potential difference between the reference electrodes approaches zero A control unit for controlling, and an analysis unit that records the potential of the reference electrode and the applied current value, and calculates an estimated value of the anticorrosion current of the sacrificial anode, and the analysis unit has a current value of 0. The hippo when Based on the potential of the outer reference electrode, the potential of the reference electrode outside the cover when the potential difference between the reference electrodes is 0, and the applied current value when the potential difference between the reference electrodes is 0, the sacrificial anode This is achieved by calculating an estimate of the anticorrosion current.

The above-described object of the present invention, Ieq said current value when said potential difference is 0, V _{out 0} the cover outer potential when the current value is _0, the cover outer potential when said potential difference is 0 Is V _out eq, and the natural potential of the metal structure is Vn, the analysis unit calculates the current value Is of the anticorrosion current,
_{Is = (V out 0-Vn} ) Ieq / (V out eq-Vn)
Or by providing the voltage measuring means independently for each reference electrode.

  The present invention relates to a current measuring device for the sacrificial anode in a galvanic anode method in which a sacrificial anode is installed on a metal structure in a conductive liquid, and the object of the present invention is to provide an insulation covering the sacrificial anode. And a pair of reference electrodes installed inside and outside the cover, and two counter electrodes respectively installed inside and outside the cover, with the cover covering the sacrificial anode, DC power supply for applying a current between the two counter electrodes, voltage measuring means for measuring a potential difference between the reference electrodes, and application of the DC power supply so that the potential difference between the reference electrodes approaches zero A control unit for controlling a current; and an analysis unit for recording a potential difference between the reference electrodes and the applied current value. The analysis unit calculates the applied current value when the potential difference is 0 to the sacrificial anode. As anti-corrosion current It is accomplished by outputting.

  According to the sacrificial anode current measuring method and current measuring apparatus according to the present invention, it is not necessary to remove the sacrificial anode from the metal structure in the liquid when measuring the sacrificial anode's anticorrosion current, and the anticorrosive current generated from the sacrificial anode is reduced. Measurement can be performed easily. Moreover, the measurement of the anticorrosion current generated from the sacrificial anode can be performed during the electrocorrosion protection.

  In the sacrificial anode current measuring method and current measuring apparatus according to the present invention, an insulating cover is installed so as to cover the sacrificial anode in the liquid, and current is applied from the counter electrode installed outside the cover. The anticorrosive current generated from the sacrificial anode is estimated from the current value of the current when the potential difference between the outside and the inside is 0.

Similarly to the case shown in FIG. 6, when the metal structure 1 is subjected to the anticorrosion by the sacrificial anode 3, there is no potential difference between the reference electrode 5A and the reference electrode 5B shown in FIG. The potential difference measured by the voltmeter 6 becomes zero. In the sacrificial anode current measuring method and current measuring apparatus according to the present invention, as shown in FIG. 1B, an insulating cover 4 is provided so as to cover the sacrificial anode 3. In this case, the anticorrosion current generated from the sacrificial anode 3 leaks through the gap between the cover 4 and the paint 2 as indicated by the dotted arrow, and an error occurs in the potential of the reference electrode 5B. Therefore, in order to cancel out this error, a current is applied between the counter electrode 7 and the metal structure 1 by the DC power supply 8 and the potential difference between the reference electrode 5A and the reference electrode 5B is set to 0, whereby the cover 4 and the paint are painted. Apparently, the current flowing through the gap with 2 is made zero. Further, in the present invention, the counter electrode 7 is provided outside the cover 4 in order to prevent an error in the measured current by greatly changing the electric field generated by the sacrificial anode 3.
The applied current is preferably a direct current, but an alternating current of about 0.2 Hz or less is also possible.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 2 is a diagram showing a configuration of a sacrificial anode current measuring apparatus according to the present invention. Similar to FIG. 6, there is a metal structure 1 in contact with a conductive liquid 20 such as seawater, and a paint 2 is applied to the boundary between the metal structure 1 and the liquid 20. In order to perform the anticorrosion by the galvanic anode method of the metal structure 1, the sacrificial anode 3 is installed at a part where the metal structure 1 contacts the liquid 20, and the metal structure 1 and the sacrificial anode 3 are electrically conductive. Connected to have.

In the sacrificial anode current measuring apparatus according to the present invention, an insulating hemispherical cover 4 is provided so as to cover the sacrificial anode 3. A reference electrode 5A is installed inside the cover 4, and a reference electrode 5B is installed outside the cover 4. The reference electrode 5A and the reference electrode 5B are connected by a conducting wire, and the potential of the reference electrode 5A is measured on the conducting wire. A grounded voltmeter 6A and a grounded voltmeter 6B for measuring the potential of the reference electrode 5B are provided. Further, a counter electrode 7 is installed outside the cover 4, the counter electrode 7 and the metal structure 1 are connected by a conductive wire, and an electric current is applied between the counter electrode 7 and the metal structure 1 on the conductive wire. A DC power supply 8 and an ammeter 9 for measuring the current value I of the applied current are provided. Note that the cover 4 is not limited to a hemispherical shape, and may be cylindrical or prismatic. The counter electrode 7 is preferably made of platinum (Pt), but may be a single metal such as silver, copper, aluminum, titanium, chromium, zinc, gold, tungsten, or an alloy thereof.
The cover 4 is preferably made of an insulating material, but if made of plastic and has an insulating property, it is represented by polyvinyl chloride (PVC), polycarbonate (PC), polypropylene (PP), or polyethylene terephthalate (PET). Any material such as polyester is acceptable. Further, a cover obtained by insulatingly coating an epoxy resin or the like on a metallic cover may be used. The cover 4 does not need to have airtightness, and the cover 4 itself may have a hole (mm order), a crack, or the like. Furthermore, the reference electrodes 5A and 5B are preferably silver / silver chloride (Ag / AgCl) electrodes, but may be mercury electrodes or calomel electrodes.
The DC power supply 8 is controlled by the control unit 10. The cover inner potential V _in measured by the voltmeter 6A, the cover outer potential V _out measured by the voltmeter 6B, and the current value I measured by the ammeter 9 are input to the analysis unit 11, and the analysis unit 11 Based on these values, the current value Is of the anticorrosion current generated from the sacrificial anode 3 is measured.

  The gap between the cover 4 and the paint 2 applied to the metal structure 1 and the hole opened in the cover 4 have little influence on the measurement result of the current value Is of the anticorrosion current, although there are some gaps. The smaller the hole, the better the measurement accuracy. Therefore, the cover 4 is installed so that the gap between the cover 4 and the paint 2 is as small as possible. In addition, the lead wire connecting the reference electrode 5A and the reference electrode 5B needs to pass through the cover 4. At this time, the hole opened in the cover 4 to pass the lead wire is insulated by, for example, sealing the periphery with rubber packing or resin. It is good to process.

The procedure for measuring the current value Is of the anticorrosion current generated from the sacrificial anode 3 in the sacrificial anode current measuring method and current measuring apparatus according to the present invention will be described with reference to the flowchart shown in FIG.
First, when no current is applied between the counter electrode 7 and the metal structure 1 (I = 0), the cover outside potential _Vout is recorded as the initial value _Vout0 (step S1). Next, the control unit 10 controls the DC power supply 8 to apply a voltage between the counter electrode 7 and the metal structure 1, and to obtain an absolute value | I | of the current value between the counter electrode 7 and the metal structure 1. Increase from 0 (step S2). At this time, the absolute value of the current | I | by increasing, as the potential difference [Delta] V ₌ V out _{-V in} the cover outer potential _{V out} and the cover inner potential _{V in} approaches 0, the control unit 10 DC The direction of the current applied between the counter electrode 7 and the metal structure 1 is set by controlling the power source 8. Then, the analysis unit 11 records the current value I, the cover inner potential V _in , and the cover outer potential V _out measured by the ammeter 9 (step S3), and determines whether the potential difference ΔV is 0 (step S4). ).

If it is determined in step S4 that the potential difference ΔV is not 0, the control unit 10 controls the DC power supply 8 so that the absolute value | I | of the current value increases (step S5). Then the process returns to step S3, the analysis unit 11 and the current value I measured by the ammeter 9, and recording a cover inner potential V _in, the cover outer potential V _out, determining whether (step potential difference ΔV is 0 S4).

When it is determined in step S4 that the potential difference ΔV is 0, the analysis unit 11 sets the current value of the current applied between the counter electrode 7 and the metal structure 1 at this time to Ieq, and sets the cover outer potential to V _out. It records as eq (step S6). Since Ieq includes a current for eliminating the polarization of the sacrificial anode 3, it is necessary to correct Ieq in order to obtain the current value Is of the anticorrosion current in a normal state where the current value I is zero. Therefore, the analysis part 11 calculates | requires the estimated value of the electric current value Is of the anticorrosion electric current which generate | occur | produces from the sacrificial anode 3 by following formula 1. (step S7).
_{Is = (V out 0-Vn} ) Ieq / (V out eq-Vn) ··· ( Equation 1)
Here, Vn is a natural potential of the metal structure 1. The current value Is of the anticorrosion current of the sacrificial anode 3 is measured by the above procedure.

Next, an experiment in which the current value Is of the anticorrosion current is measured is shown. The experiment is performed by comparing the current value Is of the anticorrosion current measured by the above-described procedure with the current value Ir0 of the anticorrosion current measured by an ammeter previously installed between the sacrificial anode 3 and the metal structure 1.
The sacrificial anode current measuring device used in this experiment is the same as that shown in FIG. In the experiment, the liquid 20 is seawater, a steel iron pipe is used as the metal structure 1, the sacrificial anode 3 is made of aluminum, and the cover 4 is made of polyvinyl chloride. However, in the experiment, an ammeter is installed in advance between the sacrificial anode 3 and the metal structure 1 in order to actually measure the current value Ir0 of the anticorrosion current.

First, the measured value Ir0 of the anticorrosion current is measured with an ammeter. The measured value Ir0 of the anticorrosion current was measured to be 95 (mA).
Then, along the procedure shown in FIG. 3, measuring an initial value V _{out 0} cover outer potential. The initial value V _out 0 of the cover outer potential was measured to be 814 (mV). Then, the absolute value | I | of the current value between the counter electrode 7 and the metal structure 1 is increased, and the current value I, the cover inner potential V _in , and the cover outer potential V _out are recorded. In this experiment, the direction of the current I is set to flow from the counter electrode 7 to the metal structure 1. Further, in this experiment, the current value (measured value) Ir of the sacrificial anode measured with an ammeter when the current value I is changed is recorded. The relationship between the current value I, the cover outer potential V _out , the cover inner potential V _in , the potential difference ΔV inside and outside the cover, and the current value Ir of the sacrificial anode 3 is shown in FIG.

As shown in FIG. 4, the potential difference ΔV becomes 0 at the point P, and the absolute value of the current value at this time is Ieq = 320 (mA). As shown in FIG. 4, at the point P, the current value Ir of the sacrificial anode 3 is 0 (mA), and the polarization of the sacrificial anode 3 is 0 (V). However, in the normal state where the applied current value I is 0, the sacrificial anode 3 is polarized, and a current for eliminating this polarization is included in Ieq = 320 (mA). In order to obtain the value Is, it is necessary to correct Ieq. The current value Is of the anticorrosion current is obtained as shown in the following equation 2 according to the above equation 1.
That is, the initial value V _out 0 = 814 (mV) of the cover outer potential, the cover outer potential V _out eq = 1150 (mV) when the potential difference ΔV = 0, and the natural potential Vn of the metal structure 1 is normally 650 to 700 ( mV), and assuming that Vn = 680 (mV) here, substituting them into Equation 1 above,
Is = (814−680) × 320 / (1150−680) = 91.2 (mA) (Formula 2)
The estimated current value Is = 91 (mA) of the anticorrosion current obtained by Expression 2 is in good agreement with the actual value Ir0 = 95 (mA) of the anticorrosion current measured in advance by an ammeter.
From this experiment, it was confirmed that the sacrificial anode current measuring method and current measuring apparatus according to the present invention can measure the anticorrosion current Is with sufficient practical accuracy.

In the above-described embodiment, when the anticorrosion current Is is obtained, the current value Ieq when the potential difference ΔV = 0 needs to be corrected according to Equation 1, but this correction is not required, and the sacrifice according to the present invention. Another configuration example of the anode current measuring device is shown in FIG.
In the sacrificial anode current measuring device shown in FIG. 5, the metal structure 1 coated with the paint 2 is in contact with the conductive liquid 20, as in the embodiment shown in FIG. 2. A sacrificial anode 3 is installed to perform anticorrosion.
An insulating cover 4 is installed so as to cover the sacrificial anode 3 so that the gap between the cover 4 and the paint 2 is as small as possible. A reference electrode 5A is installed on the inner side of the cover 4, and a reference electrode 5B is installed on the outer side of the cover 4. The reference electrode 5A and the reference electrode 5B are connected by a conductive wire, and the reference electrode 5A and the reference electrode 5B are connected to the conductive wire. Is provided with a voltmeter 6 for measuring the potential difference ΔV. Further, a counter electrode 7A is installed inside the cover 4, and a counter electrode 7B is installed outside the cover 4, so that a current is applied between the counter electrode 7A and the counter electrode 7B on the conductive wire connecting the counter electrode 7A and the counter electrode 7B. A direct current power source 8 and an ammeter 9 for measuring a current value I of a current applied between the counter electrode 7A and the counter electrode 7B are provided.
When the lead wire connecting the reference electrode 5A and the reference electrode 5B and the lead wire connecting the counter electrode 7A and the counter electrode 7B pass through the cover 4, the hole formed in the cover 4 is covered with, for example, rubber packing or resin and insulated. good.
The DC power supply 8 is controlled by the control unit 10 so that the potential difference ΔV between the reference electrode 5A and the reference electrode 5B becomes zero. The potential difference ΔV measured by the voltmeter 6 and the current value I measured by the ammeter 9 are input to the analysis unit 11, and the analysis unit 11 obtains the current value Is of the anticorrosion current generated by the sacrificial anode 3. The current Ieq may be an actually measured value of the applied current when ΔV = 0 (mV), or if the applied current cannot be adjusted so that ΔV = 0, in the graph of FIG. A value (extrapolated value) obtained by reading the current value Ieq when = 0 (mV) from the graph may be used. In the claims, the expression “the current value of the applied current when the potential difference is 0” is used to include extrapolated values.

  In the present embodiment, even when the potential difference ΔV between the outer side of the cover 4 and the inner side of the cover 4 is 0, the normal current when the current value I is 0 flows from the sacrificial anode, so that the potential difference ΔV is 0. Current value I becomes the current value Is of the anticorrosion current. Therefore, in this embodiment, the control unit 10 controls the DC power supply 8 so that a current flows in a direction in which the potential difference ΔV approaches 0, and gradually increases the absolute value of the current value I. The analysis unit 11 records the change in the current value I and the potential difference ΔV, and obtains the current value I when the potential difference ΔV is 0 as the current value Is of the anticorrosion current generated by the sacrificial anode 3.

  As mentioned above, although embodiment of this invention was described concretely, this invention is not limited to this, In the range which does not deviate from the meaning, it can change suitably.

It is a figure explaining the measurement principle of the electric current value of anticorrosion current in the electric current measurement method and electric current measurement apparatus of the sacrificial anode which concern on this invention. It is a figure which shows the structure of the current measuring apparatus of the sacrificial anode which concerns on this invention. It is a flowchart which shows the procedure which measures the electric current value of anticorrosion current in the electric current measurement method and electric current measurement apparatus of a sacrificial anode which concern on this invention. It is a figure which shows the relationship between the applied current value I, the cover inner side potential V _in , the cover outer side potential V _out , and the current value Ir of the sacrificial anode. It is a figure which shows the structure of another embodiment of the electric current measuring apparatus of the sacrificial anode which concerns on this invention. It is a figure explaining the cathodic protection by a galvanic anode system. It is a figure which shows the specific example of the apparatus which measures the anticorrosion electric current generate | occur | produced from a sacrificial anode using a voltage drop method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal structure 2 Paint 3 Sacrificial anode 4 Cover 5A, 5B Reference electrode 6, 6A, 6B Voltmeter 7, 7A, 7B Counter electrode 8 DC power supply 9 Ammeter 10 Control part 11 Analysis part 20 Liquid

Claims (16)

A method for measuring a current of the sacrificial anode in a galvanic anode method in which a sacrificial anode is installed on a metal structure in a conductive liquid,
Install an insulating cover so as to cover the sacrificial anode, and apply a current between the counter electrode installed outside the cover and the metal structure,
While measuring the electric potential outside the cover and the inside of the cover,
A sacrificial anode characterized in that a current value of the anticorrosion current is estimated from a potential outside the cover and a current value of the applied current when a potential difference between the outside of the cover and the inside of the cover is zero. Current measurement method. Ieq, the current value of the applied current when the potential difference is 0
The cover outside potential when the current value of the applied current is 0 is V _out 0,
V _out eq, the cover outside potential when the potential difference is 0,
When the natural potential of the metal structure is Vn,
The current value Is of the anticorrosion current,
_{Is = (V out 0-Vn} ) Ieq / (V out eq-Vn)
The method for measuring a current of a sacrificial anode according to claim 1, estimated by: A sacrificial anode anticorrosion current measuring method in a galvanic anode method in which a sacrificial anode is installed on a metal structure in a conductive liquid,
An insulating cover is installed so as to cover the sacrificial anode, and an electric current is applied between the counter electrode 1 installed inside the cover and the counter electrode 2 installed outside the cover, and the outside of the cover and the cover A sacrificial anode current measuring method, wherein the current value of the applied current when the potential difference inside is 0 is the current value of the anticorrosion current. The sacrificial anode current measuring method according to any one of claims 1 to 3, wherein the cover is made of polyvinyl chloride.   The method for measuring a current of a sacrificial anode according to any one of claims 1 to 4, wherein the cover is hemispherical, cylindrical, or prismatic.   The sacrificial anode current measuring method according to claim 1, wherein the counter electrode is made of at least one metal selected from platinum, silver, copper, aluminum, titanium, chromium, zinc, gold, and tungsten.   The sacrificial anode current measurement method according to claim 6, wherein the counter electrode is an alloy made of two or more metals of platinum, silver, copper, aluminum, titanium, chromium, zinc, gold, and tungsten.   The method for measuring a current of a sacrificial anode according to any one of claims 1 to 7, wherein the reference electrode is any one of a silver / silver chloride electrode, a mercury electrode, and a calomel electrode. A current measuring device for the sacrificial anode in a galvanic anode method in which a sacrificial anode is installed on a metal structure in a conductive liquid, the device comprising:
An insulating cover covering the sacrificial anode;
In a state where the cover covers the sacrificial anode, a pair of reference electrodes installed inside and outside the cover,
A counter electrode installed outside the cover;
A direct current power source for applying a current between the counter electrode and the metal structure;
Voltage measuring means for measuring the potential of each reference electrode;
A control unit for controlling an applied current of the DC power supply so that a potential difference between the reference electrodes approaches 0;
And recording the potential of the reference electrode and the applied current value, and an analysis unit for calculating an estimated value of the corrosion protection current of the sacrificial anode,
The analysis unit is configured such that the potential of the reference electrode outside the cover when the applied current value is 0, the potential of the reference electrode outside the cover when the potential difference between the reference electrodes is 0, and the potential difference between the reference electrodes A sacrificial anode current measuring device, wherein an estimated value of the corrosion protection current of the sacrificial anode is calculated based on the applied current value when the value is 0. The current value when the potential difference is 0 is Ieq,
_{V out} 0 the cover outer potential when the current value is 0,
V _out eq, the cover outside potential when the potential difference is 0,
When the natural potential of the metal structure is Vn,
The analysis unit calculates a current value Is of the anticorrosion current,
_{Is = (V out 0-Vn} ) Ieq / (V out eq-Vn)
The sacrificial anode current measuring device according to claim 9, estimated by:   The sacrificial anode current measuring device according to claim 9 or 10, wherein the voltage measuring means is provided independently for each of the reference electrodes. A sacrificial anode anti-corrosion current measuring device in a galvanic anode method in which a sacrificial anode is installed on a metal structure in a conductive liquid, the device comprising:
An insulating cover covering the sacrificial anode;
In a state where the cover covers the sacrificial anode, a pair of reference electrodes installed inside and outside the cover,
Two counter electrodes respectively installed inside and outside the cover;
A DC power source for applying a current between the two counter electrodes;
Voltage measuring means for measuring a potential difference between the reference electrodes;
A control unit for controlling an applied current of the DC power supply so that a potential difference between the reference electrodes approaches 0;
An analysis unit for recording the potential difference between the reference electrodes and the applied current value,
The sacrificial anode current measuring device, wherein the analysis unit outputs the applied current value when the potential difference is 0 as a corrosion-proof current of the sacrificial anode.   The sacrificial anode current measuring device according to claim 9, wherein the cover is made of polyvinyl chloride.   The sacrificial anode current measuring device according to claim 9, wherein the counter electrode is made of at least one metal selected from platinum, silver, copper, aluminum, titanium, chromium, zinc, gold, and tungsten.   The sacrificial anode current measuring device according to claim 14, wherein the counter electrode is an alloy made of two or more metals of platinum, silver, copper, aluminum, titanium, chromium, zinc, gold, and tungsten.   The sacrificial anode current measuring device according to any one of claims 9 to 15, wherein the reference electrode is any one of a silver / silver chloride electrode, a mercury electrode, and a calomel electrode.

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