JP5012573B2 - Buried pipe monitoring device - Google Patents

Description

  The present invention relates to a buried pipe damage monitoring apparatus, and more specifically to a buried pipe damage monitoring apparatus capable of simultaneously monitoring damage to a buried pipe and preventing corrosion of the buried pipe.

  The buried pipe buried in the ground may be damaged by a drilling machine in excavation work, and when the buried pipe is damaged, the buried pipe is corroded by contact with soil or the like. For this reason, it is necessary to quickly detect damage to the buried pipe, and various methods for monitoring the damage to the buried pipe have been studied.

  As a method for monitoring the occurrence of such damage to the buried pipe, a monitoring AC signal is constantly applied from the buried pipe transmitting section, and this is always received by the receiving section away from the transmitting section, and the resistance value is the reference. There is a method of issuing an alarm when the value falls below the value.

  In addition, when there is an existing damage to the buried pipe coating and the soil and the buried pipe steel surface are in contact with each other, there is a risk that a corrosion current flows from the buried pipe to the soil and the buried pipe is corroded.

  As a method of preventing the corrosion of the buried pipe due to the outflow of such a corrosion current, an anticorrosion DC signal corresponding to the corrosion current flowing into the buried pipe is applied to the electrode buried in the ground from the external power supply device. There is a method of electrochemically preventing the corrosion of the buried pipe.

  Thus, in the present situation, in order to monitor damage to the buried pipe and prevent corrosion of the buried pipe, the damage monitoring signal and the electric protection DC signal are separately applied to the buried pipe.

  However, if the damage monitoring signal and the cathodic protection signal are applied separately, the cathodic protection DC signal has a frequency component, not a complete DC signal, and therefore interferes with the damage monitoring signal, so that the cathodic protection in buried pipe damage monitoring. The DC signal becomes a noise source. As a result, even if the buried pipe is not damaged, the resistance value obtained from the damage monitoring signal fluctuates due to the influence of the electric protection signal, and a problem may occur in that false alarms occur due to the fluctuation value exceeding the reference value. .

As a method for preventing the occurrence of false alarms due to the influence of noise, Patent Document 1 discloses a method of comparing the current and past values after converting the received voltage into a digital quantity and performing a moving average process. A technique for detecting a change in received voltage is disclosed. Patent Document 2 discloses a technique for reducing noise by connecting a pass filter in parallel with a drain that is connected to a buried pipe.
Japanese Patent Laid-Open No. 9-33474 Japanese Patent Laid-Open No. 7-55751

  However, according to the technique disclosed in Patent Document 1, measurement data is converted into a digital value and noise is reduced by moving average processing. However, by performing moving average processing, changes in measurement values are moderated. Therefore, if the buried pipe is damaged for a short time, the damage may be overlooked. According to the technique disclosed in Patent Document 2, noise can be reduced by inserting a filter into the drain, but since the drain cannot increase the circuit resistance, a complete filter can be obtained. However, it is not sufficient from the viewpoint of noise reduction.

  The present invention has been made in view of such a situation, and by applying a superimposed signal to the buried pipe, it is possible to prevent the occurrence of noise in the buried pipe damage monitoring and there is no damage to the buried pipe. Can also prevent the occurrence of false alarms caused by the effects of noise. Furthermore, it is a main object to provide a buried pipe damage monitoring device capable of simultaneously preventing corrosion of a buried pipe by a superimposed signal.

The buried pipe monitoring device of the present invention for solving the above-mentioned problem is a damage monitoring device for underground buried pipes, which transmits a superimposed signal in which an M-sequence signal is superimposed on a DC signal from at least one transmission point of the buried pipe. The superimposed signal transmitting unit, the superimposed signal receiving unit that receives the superimposed signal, the processing unit that calculates the signal received by the superimposed signal receiving unit, the value calculated by the processing unit, and the embedded pipe are not damaged a comparing unit for comparing the reference value in the case, seen contains and a determination unit damage buried pipe in accordance with the comparison result of the comparison unit, to connect the negative terminal of the origination point to the buried pipe In addition, a reference electrode is provided at the transmission point, and control is performed so that the potential of the negative terminal and the reference electrode is constant .

Further, the superimposed signal is a DC signal applied voltage is 0.1V～60V, even superimposed signal fundamental frequency 1Hz～1000Hz, amplitude is superimposed a 0.1~10V der Ru M-sequence signal Good.

  Further, the comparison unit may compare the in-pipe current or ground resistance of the buried pipe due to the change in the correlation peak value of the M-sequence signal and those when the buried pipe is not damaged.

  The superimposed signal transmission unit may include at least an M-sequence signal generator and a highly rectified DC signal generator.

The buried pipe damage monitoring method of the present invention for solving the above-mentioned problem is a method for monitoring damage to underground pipes, and is a superimposed signal in which an M-sequence signal is superimposed on a DC signal from at least one transmission point of the buried pipe. The superimposition signal is received at the transmission point or a point away from the buried pipe, the received signal is calculated, and the calculated value is compared with a reference value when the buried pipe is not damaged. Determining whether there is damage according to the comparison result, connecting the minus side terminal of the transmission point to an embedded pipe, and providing a reference electrode at the transmission point, and the potential of the minus side terminal and the reference electrode is Control is performed so as to be constant .

Further, the superimposed signal is a DC signal applied voltage is 0.1V～60V, even superimposed signal fundamental frequency 1Hz～1000Hz, amplitude is superimposed a 0.1V~10V der Ru M-sequence signal Good.

  According to the present invention, instead of applying a corrosion prevention signal and a damage monitoring signal for a buried pipe, which have been conventionally used, to the buried pipe separately, a superimposed signal obtained by superimposing an M series signal on a DC signal is buried. By applying to, it is possible to carry out corrosion prevention of buried pipes and damage monitoring of buried pipes with a single signal, so damage monitoring can be performed without using an external power supply to send a corrosion prevention signal that was a noise source. It can be performed. This increases the grounding resistance of the buried pipe measured by the damage monitoring signal, increases the difference in grounding resistance of the buried pipe when the buried pipe is damaged, and eliminates fluctuations in the grounding resistance of the buried pipe due to noise. Can do. In other words, the present invention is characterized in that the corrosion of the buried pipe can be prevented and the damage of the buried pipe can be monitored with one signal, whereby the presence or absence of damage can be more accurately performed.

  First, the buried pipe damage monitoring apparatus of the present application will be specifically described with reference to the drawings.

  FIG. 1 conceptually shows the buried pipe damage monitoring apparatus of the present invention. As shown in FIG. 1, the superimposed signal transmission unit 11 applies a superimposed signal obtained by superimposing an M-sequence signal on a DC signal to the buried pipe 10, and connects the plus side terminal of the superimposed signal transmission unit 11 to the energizing electrode 14. At the same time, the minus side terminal 21 is connected to the buried pipe 10. The superimposition signal receiving unit 19 includes a first signal receiving unit 12 and a second signal receiving unit 13, and the first signal receiving unit 12 is configured to detect each of the verification electrode 15 and the detection tube 10 embedded in the ground. The M series pipe ground potential signal of the buried pipe 10 is received at each detection point. The second receiving unit 13 receives the M-series tube-to-tube potential of the embedded tube 10 for each measurement section, and calculates the M-series in-tube current by dividing by the conductor resistance of the embedded tube 10 in the processing unit 16. be able to. For example, the M series pipe-to-tube potential signal of the buried pipe between Q1 and Q2 connected to the detection section P1 of the buried pipe 10 is measured and divided by the conductor resistance between Q1 and Q2, and the M series pipe current Can be calculated. The processing unit 16 is provided to calculate the M series ground resistance from the signals received by the first receiving unit 12 and the second receiving unit 13. The comparison unit 17 is provided to compare the M series ground resistance calculated by the processing unit 16 with the reference value of the M series ground resistance when the buried pipe is not damaged. The determination unit 18 is provided to determine the presence / absence of an embedded pipe according to the comparison result compared by the processing device 17.

  The present invention can obtain a signal free from the influence of noise without using an external power source by applying one signal obtained by superimposing an M-sequence signal and a DC signal to the buried pipe 10 from the superimposed signal transmission unit 11. Thus, it is characterized in that the corrosion of the buried pipe can be prevented and the damage of the buried pipe can be monitored at a time. Accordingly, the tube-to-ground potential signal can be received by the first signal receiving unit 12, the tube-to-tube potential signal can be received by the second signal receiving unit 13, and the first signal receiving unit 12 and the second signal receiving unit can receive the signal. Various signals such as M series tube to ground potential, M series tube to tube potential, M series ground resistance, DC tube to ground potential, DC tube to tube potential, DC ground resistance can be measured from the signal obtained at There is no particular limitation on various means and devices for comparing these measured values with the reference values when there is no damage to the buried pipe, and determining the presence or absence of damage according to the comparison results. Can be used as appropriate. For example, the installation locations of the first signal receiving unit 12 and the second signal receiving unit 13 are R1, R2,... Rn, Q1, Q2, Q3,. -You may install in multiple places like Qn.

  In addition, in the superimposed signal transmission unit 11, a signal receiving unit 19 is installed so that the first signal receiving unit 12 receives the tube-to-ground potential signal and the second signal receiving unit 13 receives the tube-to-tube potential signal instead of superimposing. The output current of the signal transmission unit 11 may be measured.

  In addition, in the superimposed signal transmission unit 11, the reference electrode 20 may be provided and the potential of the negative terminal 21 and the reference electrode may be set to be constant. By controlling constant potential between the negative terminal 21 and the reference electrode 20, the DC tube ground potential and the M series tube ground potential become constant, and the M series ground resistance and M series tube potential can be measured more accurately. Can do.

  Next, a superimposed signal obtained by superimposing an M-sequence signal on a DC signal, which is a feature of the present invention, will be described. As described above, when the buried pipe coating is damaged and the soil and the buried pipe steel surface are in contact with each other, there is a risk that a corrosion current flows from the buried pipe to the soil and the buried pipe is corroded. Thus, the corrosion of the buried pipe can be prevented by lowering the potential of the buried pipe from the galvanic corrosion control reference value so that the corrosion current does not flow out from the buried pipe to the soil. Therefore, from this point of view, the DC signal is more preferably a DC signal such that the instantaneous maximum value of the tube-to-ground potential when the damage monitoring signal is superimposed is on the negative side with respect to the erosion control reference value. Examples of such a DC signal include a DC signal that applies 0.1V to 60V.

  The M-sequence signal is a pseudo-random signal having a fundamental frequency, and is provided for monitoring damage to the buried pipe 10 due to changes in the pipe-to-ground potential, the pipe current, and the ground resistance due to changes in the correlation peak value of the pseudo-random signal. . From such a viewpoint, the M-sequence signal is preferably an M-sequence signal having a fundamental frequency of 1 Hz to 1000 Hz and an amplitude of 0.1 V to 10 V. An M-sequence signal within such a range is effective for discrimination from commercial frequency components and prevention of AC corrosion.

  Next, a method for superimposing an M-sequence signal on a DC signal will be described.

  The method for superimposing the M series signal on the DC signal is not particularly limited as long as the M series signal can be superimposed on the DC signal, and a conventionally known method is appropriately selected. be able to. As a method for superimposing the M-sequence signal on the DC signal, for example, a method of combining a high rectification DC signal generator and an M-sequence signal generator can be cited.

  In this way, by applying one superimposed signal obtained by superimposing the M-sequence signal to the DC signal to the buried pipe, the anticorrosion effect of the buried pipe can be achieved by the effect of the DC signal, and the buried effect is obtained by the effect of the M-sequence signal. Tube damage can be monitored. Further, since corrosion prevention and damage monitoring can be performed with one superimposed signal, various signals that are not affected by noise can be obtained without using an external power supply device that has been a cause of noise generation. As a result, it is possible to prevent the occurrence of misinformation due to the influence of noise.

  The buried pipe monitoring apparatus of the present invention will be described more specifically with reference to examples.

  FIG. 2 is a diagram showing an energization device for energizing the superimposed signal in which the M-sequence signal generator 30 is connected to the high rectification DC signal generator 32 and the M-sequence signal is superimposed on the DC signal in the superimposed signal transmission unit 11. FIG. 3 is a diagram in which the energizing device of FIG. 2 is installed in the buried pipe 10.

  The energizing electrode 14 of the high rectification DC signal generator 32 is connected to the plus terminal, the minus terminal 21 is connected to the buried pipe, the reference electrode 20 is connected to the zinc verification electrode 22, and between the minus terminal 21 and the reference electrode 20 was set to be -1.5V constant. In addition, an M-sequence signal is input to the external input terminal of the high rectification DC signal generator 32, and at this time, the M-sequence applied voltage is adjusted to 4V by the amplifier 31 to simulate simulated damage. Various measurements were made of ground potential, M-series tube-to-tube potential, M-series tube current, M-series ground resistance, and DC tube-to-ground potential. As a comparative example, various measurements were performed when an external power supply and an M-sequence signal were applied in parallel. FIG. 4 shows various measurement results when a superimposed signal obtained by superimposing a DC signal and an M-sequence signal is applied to the buried pipe 10 from the superimposed signal transmission unit 11, and when an external power supply device and an M-sequence signal are applied in parallel to the route, respectively. The various measurement results are shown in FIG.

  As is apparent from FIG. 4, when a signal obtained by superimposing a DC signal and an M series signal is applied by the high rectification DC power supply 32, the DC pipe ground potential e (i) and the M series pipe ground potential a (i ) Is kept almost constant. This is because the potential of the negative terminal 21 and the reference electrode 20 is controlled at a constant potential in the high rectification DC power supply 32. Further, since the DC pipe ground potential e (i) is a negative potential from the cathodic protection control reference value, the corrosion prevention effect can be obtained by applying a superimposed signal in which the M series signal is superimposed on the DC signal to the buried pipe 10. It was confirmed that this can be achieved.

  4 and FIG. 5, it is clear that the M series tube-to-tube potential b (ii), the M series in-tube current c (ii), and the M series ground resistance d (ii) of FIG. If the fluctuation due to noise occurs due to the influence of the DC signal applied from the external power supply device and the degree of damage is low, the tube-to-tube potential and the current in the tube as shown in X (ii) and Y (ii) The increase and the decrease in ground resistance fall within the range of fluctuation when there is no damage, and the damage cannot be detected. On the other hand, when a signal in which a DC signal and an M-sequence signal are superimposed is applied to the buried pipe 10, even if the degree of damage of the buried pipe 10 is low, as shown by X (i) and Y (i), The increase in the tube-to-tube potential and the current in the tube and the decrease in the grounding resistance are hardly affected by noise, and the increase in the tube-to-tube potential and the current in the tube and the decrease in the grounding resistance do not damage the embedded tube 10. The damage can be accurately detected by comparing with the reference value of the case.

It is the figure which showed the buried pipe damage monitoring apparatus notionally. It is a figure which shows the electricity supply apparatus for supplying with the superimposed signal which superimposed the M series signal on the direct-current signal. It is the figure which installed the electricity supply apparatus of FIG. 2 in the buried pipe. It is a figure which shows each measured value at the time of superimposition signal application. It is a figure which shows each measured value at the time of the DC output by an external power supply.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Embedded pipe 11 ... Superimposition signal transmission part 12 ... 1st signal receiving part 13 ... 2nd signal receiving part 14 ... Current supply electrode 15 ... Collation electrode 16 ... Processing part 17 ... Comparison part 18 ... Determination part 19 ... Signal receiving part 20 Reference electrode 21 Negative terminal 30 M-sequence signal transmitter 31 Amplifier 32 High rectification DC power supply

Claims (6)

In the damage monitoring device for underground pipes,
A superimposition signal transmitter for transmitting a superposition signal in which an M-sequence signal is superposed on a DC signal from at least one transmission point of the buried pipe;
A superimposed signal receiving unit for receiving the superimposed signal;
A processing unit for calculating a signal received by the superimposed signal receiving unit;
A comparison unit that compares the value calculated by the processing unit with a reference value when the buried pipe is not damaged;
A determination unit for determining damage of the buried pipe according to the comparison result in the comparison unit;
Only including,
A buried pipe characterized in that a negative terminal of the transmission point is connected to an embedded pipe, a reference electrode is provided at the transmission point, and the potential of the negative terminal and the reference electrode is controlled to be constant . Damage monitoring device. The superimposed signal is a DC signal applied voltage is 0.1V～60V, and wherein the fundamental frequency 1Hz～1000Hz, a superimposed signal amplitude is superimposed a 0.1~10V der Ru M-sequence signal The buried pipe monitoring apparatus according to claim 1.   The comparison section compares the in-pipe current or grounding resistance of the buried pipe due to a change in the correlation peak value of the M-sequence signal with those when the buried pipe is not damaged. Or the buried pipe damage monitoring device according to 2;   The buried pipe damage monitoring apparatus according to any one of claims 1 to 3, wherein the superimposed signal transmission unit includes at least an M-sequence signal generator and a high rectification DC signal generator. A method for monitoring damage to underground pipes,
A superimposition signal in which an M series signal is superimposed on a DC signal is transmitted from at least one transmission point of the buried pipe,
The superimposed signal is received at the transmission point or a point away from the buried pipe,
Calculating the received signal;
Compare the calculated value with a reference value when the buried pipe is not damaged,
According to the comparison result and determining the presence or absence of damage ,
Embedded pipe damage characterized by connecting a minus side terminal of the transmission point to an embedded pipe and providing a reference electrode at the transmission point and controlling the potential of the negative side terminal and the reference electrode to be constant. Monitoring method. The superimposed signal is a DC signal applied voltage is 0.1V～60V, and wherein the fundamental frequency 1Hz～1000Hz, a superimposed signal amplitude is superimposed a 0.1V~10V der Ru M-sequence signal The buried pipe damage monitoring method according to claim 5.

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