JP6498147B2 - Pipe corrosion estimation method and pipe corrosion estimation apparatus - Google Patents

Description

  The present invention relates to a pipe corrosion estimation method and a pipe corrosion estimation apparatus.

  For operators who maintain and manage pipelines, dealing with pipeline corrosion is one of the most important issues. For example, most of the low-carbon steel pipes installed by the applicant in the 1960s and 1970s are functioning normally. However, some pipes are blocked by corrosion or are resistant to earthquakes. There was a problem of being damaged.

  In order to solve the above problems, it is required to establish a simple method for grasping the corrosion amount and corrosion rate of each pipe line at the site where the pipe line is provided.

  Conventionally, the inspection of the corrosion state of a communication pipeline has been performed by inserting a pipe camera 60 into a pipeline 55 and confirming it from the road, for example, as shown in FIG. In the example of FIG. 9, the stagnant water in the manholes 50 on both sides is drained for each one of the pipelines, an operator enters the manhole 50, passes the string 70 into the pipeline 55, and then connects the pipe camera 60 to the string. The interior of the pipe 55 is photographed by pulling at 70.

  Also, methods used for non-communication pipes include magnetic flux leakage pigs for detecting coating loss and thinning, and methods using ultrasonic pigs for inspecting thinning. Patent Document 1). The method using the magnetic flux leakage pig is to magnetize a pipe that is a ferromagnetic material to generate a magnetic flux, and detect a distortion of the magnetic flux due to a coating loss or a thinning. The ultrasonic pig is a method of measuring the thickness by filling the liquid between the inner surface of the pipe and the pig and generating ultrasonic waves.

  In addition, when a pig cannot be inserted into a pipeline, a method is used in which a device is installed on the surface of the pipeline and ultrasonic waves are propagated in the axial direction to check for thinning due to corrosion (non-pipe). Patent Document 1).

  Non-Patent Document 2 discloses a technique for estimating corrosion of a pipe line using an AC impedance method. In this method, the corrosion resistance of the ductile cast iron pipe embedded in the soil is measured by immersing the ductile test piece in the soil extraction water obtained by drying and adding water to the collected soil, and measuring the corrosion resistance. Is to predict.

Edited by IEEJ / Electric Corrosion Prevention Research Committee, “Electric Corrosion Prevention / Anti-corrosion Handbook”, p.352-358 Hiroaki Fujii and 4 others, “Method of predicting corrosion of ductile cast iron pipe using AC impedance method”, Materials, Vol. 51, No. 11, p.1203-1209 (2002) Akira Ito, et al, "ELECTROCHEMICAL MEASUREMENT TO EXAMINE INFLUENCE OF IONS, DO AND PH ON CORROSION OF LOW CARBON STEEL CONDUITS" 17003, 17th APCCC (2016) Masatoshi Kato and Masaaki Koyama, “On the improvement of the polarization resistance method”, Anticorrosion Technology, 34, p.215-221 (1985) Corrosion and Corrosion Protection Association, “Corrosion and Corrosion Prevention Handbook”, p.551

  However, in the method using a pipe camera or various pigs, in order to insert the camera or pig inside the pipeline, the manhole covers on both sides of the pipeline to be inspected are opened to drain the water in the pipeline and the manhole. Because it is necessary, inspection takes time. In addition, when a cable or the like is provided in the pipeline, the camera or pig may not be inserted.

  Further, in the method of propagating ultrasonic waves in the axial direction of the pipe line, it is necessary to bring a terminal into contact with the outer peripheral surface of the pipe line, so that excavation of the pipe line is required and large-scale construction is required.

  Further, in the method according to Non-Patent Document 2, since it is necessary to collect soil, there is a case where large-scale construction is involved.

  Therefore, the objective of this invention made | formed in view of this point is providing the method for estimating corrosion of a pipe line easily in the field | area where the pipe line is arrange | positioned.

In order to solve the above problems, a method for estimating corrosion of a pipeline according to the present invention is as follows.
Connecting at least one pair of facing electrodes to a floating body floating with respect to the measurement liquid, and projecting a part of the electrode downward from the liquid surface height of the measurement liquid when the floating body is floating;
Suspending the floating body in the measurement liquid and exposing a part of the electrode to the measurement liquid;
Applying an electrical signal between the at least one set of electrodes and measuring an impedance between the at least one set of electrodes from a response to the electrical signal;
Calculating a polarization resistance of the electrode from the impedance;
Estimating the corrosion of the pipeline from the polarization resistance,
The measurement liquid is stagnant water in a manhole connected to the pipeline,
The at least one set of electrodes is formed of the same material as the conduit.

Moreover, in order to solve the above-mentioned problem, a corrosion estimation device for a pipeline according to the present invention is:
An electrode unit having at least one pair of electrodes facing each other and a floating body connected to the at least one pair of electrodes and floating with respect to the measurement liquid;
An impedance measurement unit that applies an electrical signal between the at least one set of electrodes and measures an impedance between the at least one set of electrodes from a response to the electrical signal;
A calculation unit for calculating the polarization resistance of the electrode from the impedance;
A corrosion estimation unit for estimating the corrosion of the pipe line from the polarization resistance,
The measurement liquid is stagnant water in a manhole connected to the pipeline,
The at least one set of electrodes is formed of the same material as the conduit,
When at least a part of the pair of electrodes protrudes downward from the liquid level of the measurement liquid when the floating body is floating, and the floating body is suspended in the measurement liquid, a part of the electrode becomes the measurement liquid. It is characterized by being exposed.

  ADVANTAGE OF THE INVENTION According to this invention, the technique for estimating corrosion of a pipe line easily can be provided in the field where the pipe line is arrange | positioned.

It is a perspective view which shows the structure of the electrode Assy used for the corrosion estimation apparatus of the pipe line which concerns on 1st Embodiment of this invention. It is a figure which shows the structure of the electrode used for the corrosion estimation apparatus of the pipe line which concerns on 1st Embodiment of this invention. It is (a) top view, (b) front view, and (c) right view which show the structure of the electrode Assy used for the corrosion estimation apparatus of the pipe line concerning 1st Embodiment of this invention. It is a figure which shows the structure of the whole corrosion estimation apparatus of the pipe line which concerns on 1st Embodiment of this invention. It is a figure which shows the equivalent circuit of the electrode and measurement liquid in the corrosion estimation apparatus of the pipe line of FIG. It is a figure which shows an example of the measurement result of the alternating current impedance by the corrosion estimation apparatus of the pipe line of FIG. It is a flowchart which shows the procedure of the corrosion estimation method of the pipe line which concerns on 1st Embodiment of this invention. It is a figure which shows the structure of the whole corrosion estimation apparatus of the pipe line which concerns on 2nd Embodiment of this invention. It is a figure which shows the inspection method of the pipe line using the conventional pipe camera.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram showing a configuration of an electrode Assy 100 used in a pipe corrosion estimation apparatus 200 according to the first embodiment of the present invention. The electrode Assy 100 of this embodiment includes a pair of electrodes 10 formed by cutting out from a pipe steel pipe, and a floating body 20 for floating the electrodes 10 in manhole stagnant water that is a measurement liquid. In the present specification, the vertical direction means the longitudinal direction of the electrode 10 in FIG. 1, and the upper side is the side where the connecting member 24 is located when viewed from the leg member 22 (upward in FIG. 1). The lower side is the opposite side. Further, the front-rear direction means a direction along the longitudinal direction of the leg member 22, and the left-right direction means a direction along the longitudinal direction of the connecting member 24.

  In the present embodiment, the set of electrodes 10 is formed by cutting out a cylindrical carbon steel pipe for piping (abbreviated as SGP (Steel Gas Pipe)) in the longitudinal direction, and further, as shown in FIGS. It is a pair of electrodes formed by cutting out part of the direction. In addition, as SGP used for this embodiment, although the carbon steel pipe JIS-G-3452 for piping etc. which are defined by Japanese Industrial Standard (JIS) can be used, for example, it is not limited to this. In the present embodiment, the electrode 10 is preferably cut out from a steel pipe having the same manufacturer and model number as the steel pipe used in the pipe line to be estimated for corrosion. However, it is not always necessary to cut out and use a part of the steel pipe itself that is actually used as a pipe line, and it may be cut out from a new steel pipe. Further, if the material of the steel pipe is approximate, the electrode 10 may be formed by cutting out from a steel pipe of a manufacturer and model number different from that of the steel pipe used for the pipe to be estimated for corrosion. As shown in FIGS. 1 and 3, the pair of electrodes 10 are fixed side by side on the front and back sides of the connecting member 24 that connects the two leg members 22 so that the inner peripheral surfaces of the SGP face each other. Has been. In the present embodiment, the pair of electrodes 10 are cut out to have substantially the same length in the longitudinal direction and the circumferential direction, and are arranged so that the upper end and the lower end are approximately the same height on the side surface of the connecting member 24. ing.

  In the present embodiment, a set of electrodes 10 is used. However, the present invention is not limited to this mode, and two or more sets of electrodes 10 may be arranged facing each other. .

  The floating body 20 includes a connecting member 24 that fixes a pair of opposing electrodes 10, and a pair of leg members 22 that are connected to lower surfaces of both ends in the longitudinal direction (left-right direction) of the connecting member 24. That is, the connecting member 24 connects the set of electrodes 10 on the front and back side surfaces, and connects the set of leg members 22 on the lower surfaces of the left and right ends. In the present embodiment, the electrode 10 is fixed to the floating body 20 at a position where the lower end protrudes further downward from the liquid level of the manhole staying water in a state where the floating body 20 is floating in the manhole staying water. With this configuration, when the electrode Assy 100 is suspended in the manhole stagnant water, a part of the electrode 10 protruding downward is exposed to the manhole stagnant water.

  In the present embodiment, bead-method expanded polystyrene (abbreviated as EPS (Expanded Polystyrene)) is used as the material of the floating body 20, but the embodiment is not limited thereto. Measurements of this embodiment include other foamed materials such as extruded polystyrene (abbreviated XPS (Extruded Polystyrene)), or any material that floats in water, such as wood, as well as molded members that have been made hollow to ensure buoyancy. The floating body 20 can be configured using various members that float in manhole stagnant water that is a liquid. Further, in the floating body 20, the leg member 22 that is in direct contact with the measurement liquid and is floated may be formed of a foamed member, and the connecting member 24 may be formed of another material that is not floating in the measurement liquid.

  In the present embodiment, the pair of leg members 22 that float in direct contact with the manhole stagnant water are arranged such that the longitudinal direction is the front-rear direction, so that the electrode Assy 100 falls in the front-rear direction even when receiving wind. It has a difficult structure. In addition, the pair of leg members 22 are arranged with a gap in the short direction (left and right direction), and similarly have a configuration that is not easily tilted in the left and right direction. The set of leg members 22 is connected by a connecting member 24 at the center in the longitudinal direction, and the set of electrodes 10 is fixed at the center in the longitudinal direction of the connecting member 24. As described above, the electrode Assy100 is configured in a well-balanced manner so that it does not easily fall down in any of the front, rear, left, and right directions, and thus has a feature that it does not easily fall over even if it receives wind from a ventilation fan during measurement.

  In addition, the structure of the leg member 22 is not limited to said aspect. For example, instead of the pair of leg members 22, two front and rear openings are provided in a leg member having substantially the same length in the front and rear and left and right, and the electrode 10 is configured to protrude downward from the openings. May be.

  FIG. 2 is a diagram showing a detailed configuration of the electrode 10 used in the pipe corrosion estimation apparatus 200 according to the present embodiment. FIG. 2 shows only one electrode 10 of the set of electrodes 10. As shown in the figure, the electrode 10 according to the present embodiment has a detection unit 12 on the inner peripheral surface side of the steel pipe. The electrode 10 is subjected to insulation treatment (insulation treatment portion 14) in the region excluding the detection portion 12, and the outer peripheral surface of the steel pipe not shown in FIG. 2 is also subjected to insulation treatment. As a result, electrons move between the electrode 10 and the measurement liquid only through the detection units 12 that face the pair of electrodes 10, and a current flows.

  In the present embodiment, as the size of the electrode 10, the length of the string in the circumferential direction: 20 millimeters, the length in the vertical direction: 150 millimeters, and the size of the detection unit 12: 20 millimeter square are adopted. The center of the detection unit 12 is provided approximately 20 millimeters above the lower end of the electrode 10. However, it is not limited to this size, and various other shapes and sizes can be adopted.

  In this embodiment, an epoxy adhesive such as Araldite (registered trademark) is used as the insulation treatment, but the present invention is not limited to this embodiment, and another adhesive such as a silicon adhesive is used. Alternatively, various other insulating treatments such as coating with a fluororesin may be used.

  Further, in the present embodiment, as shown in FIG. 2, except for the detection unit 12, all the regions on the front and back of the electrode 10 are insulated, but the present invention is not limited to this mode. . For example, only the portion of the electrode 10 that protrudes downward from the leg member 22 may be configured to insulate the back surface of the detection unit 12.

  As shown in FIG. 2, a conductive wire 30 is provided above the upper end of the electrode 10, and electrically connects a measurement unit 48 (described later) and the electrode 10.

  FIG. 3 shows (a) a plan view, (b) a front view, and (c) a right side view of the electrode Assy 100 according to the present embodiment. In addition, although the dimension of each part of electrode Assy100 is described in the figure, these are examples to the last, and are not limited to this magnitude | size.

  In FIG. 3C, a sub coupling member 26 is disposed below the leg member 22. The sub coupling member 26 couples the electrodes 10 together with the coupling member 24. As described above, the electrodes 10 are connected to each other at the upper and lower portions of the leg member 22 so that the distance between the electrodes 10 can be always kept constant. Since the width in the left-right direction of the sub-connecting member 26 is equal to the length of the string of the electrode 10, the sub-connecting member 26 cannot be seen behind the electrode 10 in FIG.

  As shown in FIG. 3 (b), the detection unit 12 is provided with a size of 20 mm square about 20 mm above the lower end of the electrode 10. As will be described later, when the electrode Assy 100 is suspended on the surface of the manhole stagnant water, the electrode 10 is exposed to the manhole stagnant water from the lower end to an area of about 60 millimeters. Accordingly, the entire detection unit 12 is exposed to the manhole stagnant water.

  FIG. 4 is a diagram showing an overall configuration of a pipe corrosion estimation apparatus 200 according to the present embodiment. The measurer first opens the manhole 50 connected to the pipe 55 to be estimated for corrosion, enters the manhole 50, and floats the electrode Assy100 on the liquid surface WS of the manhole stagnant water. At this time, the floating body 20 is maintained in a state where the bottom surface of the leg member 22 is slightly lowered from the liquid level WS by its own buoyancy. The electrode 10 is fixed to the floating body 20 with its lower end protruding downward from the bottom surface of the leg member 22 as shown in FIGS. 1, 3B, and 3C. For this reason, when the electrode Assy 100 is floated on the liquid level WS of the manhole stagnant water as shown in FIG. 4, the portion of the electrode 10 that protrudes downward from the bottom surface of the leg member 22 is exposed to the manhole stagnant water. As shown in FIG. 3B, the electrode 10 is arranged so that all the detection units 12 protrude downward from the bottom surface of the leg member 22. Therefore, when the electrode Assy 100 is suspended in the manhole stagnant water, the detection unit 12. Is completely exposed to manhole dwelling water.

  The electrode Assy 100 is electrically connected to a measurement unit 48 arranged on the ground by a conducting wire 30.

  The measurement unit 48 includes functions of a frequency response analyzer 481 (abbreviated as FRA (Frequency Response Analyzer)) and a potentiostat 482 (Potentiostat), and a constant voltage AC signal between the pair of electrodes 10 via the conductor 30. And the impedance between the electrodes 10 is measured from the response thereto. More specifically, the frequency response analyzer 481 outputs the frequency of the AC signal having an amplitude of 10 mVp-p while sweeping from 10 millihertz to 20 kilohertz. The potentiostat 482 functions as a constant voltage power supply, and converts the AC signal output from the frequency response analyzer 481 into an AC signal with a low output impedance that is not affected by load fluctuations, and outputs the AC signal.

  The frequency response analyzer 481 applies the above-described AC signal between the pair of electrodes 10 and measures the impedance between the electrodes 10 from the current response for each frequency. In this embodiment, an AC signal from a constant voltage power supply is applied and impedance is measured from a current response at each frequency with respect to the AC signal. However, the present invention is not limited to this mode. You may comprise so that an impedance may be measured from the voltage response with respect to it applying an alternating current signal.

  In the present embodiment, the measurement unit 48 is connected to a measurement PC (Personal Computer) 46, and the measurer controls the measurement unit 48 by transmitting various control commands from the measurement PC 46. Impedance data at each frequency measured by the measurement unit 48 is transmitted to and stored in the measurement PC 46, and is used for calculation of polarization resistance and the like. For communication between the measurement PC 46 and the measurement unit 48, various interfaces such as Ethernet (registered trademark), USB (Universal Serial Bus) (registered trademark), and GPIB (General Purpose Interface Bus) can be used.

  It is known that the equivalent circuit shown in FIG. 5 can be applied to the calculation of the polarization resistance by the AC impedance method (two-electrode method) adopted in the present embodiment (Non-patent Documents 3 and 4). In FIG. 5, Rp is polarization resistance, which is resistance when metal atoms are ionized on the surface of the electrode 10, and means resistance to corrosion reaction. Rsol is a solution resistance and means a resistance when ions generated in the electrode 10 move between the electrodes 10 through the manhole retention liquid.

  FIG. 6 shows the result of measuring the impedance Z obtained by the above-described method when the frequency is changed from 10 millihertz to 20 kilohertz on a polar coordinate system with the real part as the horizontal axis and the imaginary part as the vertical axis. The drawn Nyquist diagram is shown. The impedance Z theoretically draws a semicircle whose diameter is a straight line connecting Z = Rsol + 2 × Rp (when the frequency is 0) and Z = Rsol (when the frequency is infinite). Therefore, by approximating each measurement point indicated by a white circle in FIG. 6 with a semicircle, and reading real part values ReZ1 and ReZ2 when the approximate curve intersects the real axis, Rsol = ReZ1, Rp = (ReZ2−ReZ1) ) / 2, Rp and Rsol can be obtained. For example, the least square method can be used for fitting from the measurement point to the approximate curve of the semicircle.

  In the present embodiment, the measurement result of the impedance Z is represented in the Nyquist diagram so that Rp and Rsol are obtained. However, the present invention is not limited to this mode. For example, a configuration may be adopted in which Rp and Rsol are obtained by drawing a Bode diagram of impedance Z.

By the way, the Stern-Gary equation icorr = k / Rp (1)
(Icorr is the corrosion current, k is a constant)
Therefore, the reciprocal number of the polarization resistance Rp is proportional to the corrosion rate (corrosion current) (Non-patent Document 5). Therefore, in this embodiment, the polarization resistance Rp is used to determine the degree of corrosion. That is, the determination of the degree of corrosion is performed by relatively evaluating the polarization resistance Rp measured in each manhole 50 and determining that a portion having a lower polarization resistance Rp is most easily corroded. When the polarization resistance Rp is smaller than 1000Ω, it is determined that the corrosion rate may be particularly high.

  The polarization resistance Rp measured in the present embodiment is a resistance when metal atoms are ionized on the surface of the electrode 10, and is determined by the material of the electrode 10 and the quality of the measurement liquid. Therefore, if the above-described polarization resistance Rp is measured using the measurement liquid having the same liquid quality as the accumulated water in the estimation target pipe 55 and the electrode 10 made of the same material as the estimation target pipe 55, the pipe 55 It is possible to estimate the corrosion of the steel. Therefore, it is not always necessary to form the electrode 10 by cutting out from a steel pipe that is actually used as the pipe line 55 and undergoing corrosion.

  FIG. 7 is a flowchart showing the procedure of the pipe corrosion estimation method according to the present embodiment. First, the measurer forms the floating body 20 by connecting the connecting member 24, the leg member 22, and the sub-connecting member 26 made of foamed members by means of adhesion, fusion, or the like, and then the detection unit of the set of electrodes 10. A part including 12 is fixed to the floating body 20 so as to protrude downward so as to be exposed to the manhole stagnant water, and the electrode Assy 100 is formed (step S101). In forming the electrode Assy 100, an insulating process is performed on a region other than the detection unit 12 of the electrode 10. Further, the electrode 10 is formed by cutting out from a steel pipe of the same manufacturer and model number as the pipe 55 to be estimated for corrosion. In addition, formation of the electrode Assy100 in step S101 may be performed by an operator other than the measurer, or may be automatically assembled by an apparatus. Next, the measurer opens the manhole 50, enters the manhole 50, and floats the electrode Assy100 formed in step S101 on the liquid level WS of the manhole stagnant water. At this time, the detection part 12 provided in the part protruded downward from the floating body 20 among the electrodes 10 is exposed to manhole residence water (step S103). Of the portion of the electrode 10 exposed to the manhole stagnant water, the portion other than the detection unit 12 is covered and insulated by Araldite (registered trademark).

  By the way, since mud etc. are accumulated at the bottom of the manhole 50, if the electrode 10 is completely submerged by its own weight, there is a possibility that the electrode 10 is covered with mud and the polarization resistance Rp cannot be measured accurately. In the measurement and calculation of the polarization resistance Rp, it is considered desirable to measure the polarization resistance Rp using the supernatant without scattering the manhole stagnant water as much as possible. Therefore, in the present embodiment, only a part of the electrode 10 including the detection unit 12 is exposed to the manhole stagnant water. Further, in the measurement and calculation of the polarization resistance Rp, the ventilation in the manhole 50 is necessary even during the measurement, so that the electrode Assy100 is not easily overturned even when receiving the wind of the ventilation fan. Specifically, a pair of leg members 22 are arranged in a row in the short direction so as to be difficult to transfer in the short direction in addition to the longitudinal direction of the leg member 22. Further, the set of leg members 22 is connected by a connecting member 24 at the center in the longitudinal direction, and the set of electrodes 10 is fixed at the center in the longitudinal direction of the connecting member 24. Thus, the electrode Assy100 is configured in a well-balanced manner so that it does not easily fall in any of the front, rear, left, and right directions.

  Next, the measurer transmits various control commands from the measurement PC 46 to the measurement unit 48, and causes the measurement unit 48 to start impedance measurement (step S105). The measurement unit 48 applies a constant voltage AC signal to the set of electrodes 10 via the conductive wire 30 and measures the impedance from the response signal. That is, the measurement unit 48 functions as an impedance measurement unit.

  Next, the polarization resistance Rp is calculated from the impedance measured in step S105 (step S107). The polarization resistance Rp can be calculated by, for example, an application running on the measurement PC 46 acquiring impedance data from the measurement unit 48 and automatically calculating the impedance data. In this case, the measurement PC 46 functions as a calculation unit. The measurement unit 48 may be configured to automatically calculate the polarization resistance Rp from the measured impedance (in this case, the measurement unit 48 functions as a calculation unit), or from the impedance data measured by the measurer. The polarization resistance Rp may be calculated manually (in this case, the measurer functions as a calculation unit).

  Finally, corrosion of the pipeline 55 is estimated from the value of the polarization resistance Rp calculated in step S107 (step S109). According to the Stern-Gary equation, the reciprocal of the polarization resistance Rp is proportional to the corrosion rate (corrosion current) (Non-Patent Document 5). Therefore, the polarization resistance Rp acquired in each manhole 50 is relatively evaluated. It is determined that a portion having a smaller polarization resistance Rp is most easily corroded. When the polarization resistance Rp is lower than 1000Ω, it is determined that the corrosion rate is particularly high. Further, the degree of corrosion of the pipeline 55 can be determined from the polarization resistance Rp and the number of years since the pipeline 55 was installed. The estimation of the corrosion of the pipeline 55 can be configured such that, for example, an application executed on the measurement PC 46 estimates the corrosion of the pipeline 55 from the value of the polarization resistance Rp. In this case, the measurement PC 46 functions as a corrosion estimation unit. Further, the measurer may estimate the corrosion of the pipe 55 from the value of the polarization resistance Rp. In this case, the measurer plays a role of a corrosion estimation unit.

  As described above, according to the present embodiment, when a pair of electrodes 10 for measuring the polarization resistance Rp is fixed to the floating body 20 to form the electrode Assy100, and the electrode Assy100 is suspended in the manhole stagnant water, A part of the electrode 10 projecting to the surface is exposed to manhole stagnant water so that the impedance between the electrodes 10 can be measured and the polarization resistance Rp can be calculated. As a result, it is possible to estimate the degree of corrosion on the inner surface of the pipe 55 and to make a future prediction without draining the water in the manhole 50 and with or without the cable in the pipe 55. And it becomes possible to shorten the time to grasp | ascertain the degree of corrosion, and to reduce a construction scale.

  Moreover, according to this embodiment, it comprised so that an insulating film might be provided in the surface on the opposite side to the surface which mutually opposes among the parts exposed to the manhole residence water of a set of electrodes 10. FIG. As a result, an electrochemical reaction does not occur on the surface opposite to the facing surface, so that the measurement accuracy of the polarization resistance Rp is improved.

  In addition, according to the present embodiment, the set of electrodes 10 is cut out and formed from a steel pipe made of the same material as the steel pipe that is actually disposed, so that corrosion can be estimated more accurately. .

  Further, according to the present embodiment, the pair of leg members 22 are arranged to be spaced apart from each other in the left-right direction, and the pair of leg members 22 are connected by the connecting member 24 to form the floating body 20. The set of electrodes 10 was fixed so as to extend downward from the side surface of the connecting member 24 between the set of leg members 22, thereby forming the electrode Assy 100. This makes it difficult for the electrode Assy 100 to fall to the left and right, and because the electrode 10 is disposed between the leg members 22 in a well-balanced manner, even if the ventilation fan is operated in the manhole 50, the electrode Assy 100 easily falls by the wind. There is nothing to do.

(Second Embodiment)
Next, a pipe corrosion estimation apparatus 300 according to the second embodiment of the present invention will be described with reference to FIG. The pipe corrosion estimation apparatus 300 according to the present embodiment is not different from the first embodiment except that the configuration of the measurement PC 66 and the measurement unit 68 is different from that of the first embodiment. Therefore, here, the description will focus on the differences from the first embodiment.

  In FIG. 8, the measurement unit 68 is disposed in the manhole 50 as in the first embodiment. On the other hand, the measurement PC 66 is disposed outside the manhole 50. The measurement unit 68 and the measurement PC 66 are connected by wireless communication. The measurer transmits various control commands by wireless communication from the measurement PC 66 to the transmission / reception unit 683 of the measurement unit 68 to cause the measurement unit 68 to start impedance measurement. When the impedance measurement is completed, the transmission / reception unit 683 of the measurement unit 68 transmits impedance measurement data to the measurement PC 66 by wireless communication. In this case, the transmission / reception unit 683 of the measurement unit 68 functions as a transmission unit, and the measurement PC 66 corresponds to an external device. The measurement PC 66 calculates the polarization resistance Rp using the received impedance measurement data, and estimates the corrosion of the pipeline 55. Note that the measurement unit 68 may automatically calculate the polarization resistance Rp and transmit the data of the polarization resistance Rp to the measurement PC 66 by wireless communication.

  In this embodiment, WiFi (Wireless Fidelity) (registered trademark) is used for the above-described wireless communication. However, the present invention is not limited to this mode. For example, ZigBee (registered trademark) of the short-range wireless communication standard is used. ) And other various wireless communication standards may be used.

  As described above, in this embodiment, the measurement unit 68 is arranged in the manhole 50, while the measurement PC 66 is arranged outside the manhole 50, and both are connected by wireless communication. As a result, the measurement can be continued with the lid of the manhole 50 closed, so that the periodic monitoring of the polarization resistance Rp is facilitated.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention. For example, the functions included in each component, each step, etc. can be rearranged so that there is no logical contradiction, and multiple components, steps, etc. can be combined or divided into one It is. Further, although the present invention has been described mainly with respect to the apparatus, the present invention can also be realized as a method, a program executed by a processor included in the apparatus, or a storage medium storing the program, and is within the scope of the present invention. It should be understood that these are also included.

DESCRIPTION OF SYMBOLS 10 Electrode 12 Detection part 14 Insulation processing part 20 Floating body 22 Leg member 24 Connection member 26 Subconnection member 30 Conductor 46 Measurement PC (calculation part, corrosion estimation part)
48 Measurement unit (impedance measurement unit, calculation unit)
50 Manhole 55 Pipeline 60 Pipe camera 66 PC for measurement (Calculation unit, corrosion estimation unit, external equipment)
68 Measurement unit (impedance measurement unit, calculation unit)
70 string 100 electrode assembly (electrode unit)
200,300 Pipe corrosion estimation device 481,681 Frequency response analyzer 482,682 Potentiostat 683 Transmitter / receiver (transmitter)
Rp Polarization resistance Rsol Solution resistance WS Liquid level Z Impedance

Claims (8)

Connecting at least one pair of facing electrodes to a floating body floating with respect to the measurement liquid, and projecting a part of the electrode downward from the liquid surface height of the measurement liquid when the floating body is floating;
Suspending the floating body in the measurement liquid and exposing a part of the electrode to the measurement liquid;
Applying an electrical signal between the at least one set of electrodes and measuring an impedance between the at least one set of electrodes from a response to the electrical signal;
Calculating a polarization resistance of the electrode from the impedance;
Estimating corrosion of the pipeline from the polarization resistance,
The measurement liquid is stagnant water in a manhole connected to the pipeline,
The method for estimating corrosion of a pipe line, wherein the at least one set of electrodes is formed of the same material as the pipe line.   The method for estimating corrosion of a pipe line according to claim 1, further comprising a step of providing an insulating film on at least a surface opposite to a surface facing each other in a part of the electrode.   The pipe corrosion estimation method according to claim 1, further comprising the step of cutting the at least one set of electrodes from a steel pipe.   The floating body includes a set of leg members that are spaced apart and aligned in the horizontal direction, and a connecting member that extends in the horizontal direction and connects the set of leg members, and the at least one set of electrodes includes the set of legs. The pipe corrosion estimation method according to any one of claims 1 to 3, wherein the pipe member is fixed so as to extend downward from a side surface of the connecting member between the leg members.   The pipe line corrosion estimation method according to any one of claims 1 to 4, further comprising a step of transmitting at least one of the impedance and the polarization resistance to an external device by wireless communication. An electrode unit having at least one pair of electrodes facing each other and a floating body connected to the at least one pair of electrodes and floating with respect to the measurement liquid;
An impedance measurement unit that applies an electrical signal between the at least one set of electrodes and measures an impedance between the at least one set of electrodes from a response to the electrical signal;
A calculation unit for calculating the polarization resistance of the electrode from the impedance;
A corrosion estimation unit for estimating the corrosion of the pipe line from the polarization resistance,
The measurement liquid is stagnant water in a manhole connected to the pipeline,
The at least one set of electrodes is formed of the same material as the conduit,
When at least a part of the pair of electrodes protrudes downward from the liquid level of the measurement liquid when the floating body is floating, and the floating body is suspended in the measurement liquid, a part of the electrode becomes the measurement liquid. An apparatus for estimating corrosion of pipelines, characterized by being exposed.   The floating body includes a set of leg members that are spaced apart and aligned in the horizontal direction, and a connecting member that extends in the horizontal direction and connects the set of leg members, and the at least one set of electrodes includes the set of legs. The pipe corrosion estimation apparatus according to claim 6, which is fixed so as to extend downward from a side surface of the connecting member between the leg members.   The pipe corrosion estimation apparatus according to claim 6 or 7, further comprising a transmission unit configured to transmit at least one of the impedance and the polarization resistance to an external device by wireless communication.

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