JP2001194340A - Measuring instrument for state of cathodic protection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the maintenance control on the state of corrosion protection of a cathodically protected underground buried pipe, or the like. SOLUTION: This measuring instrument 1 or the state of cathodic protection has a processing circuit 10, a display 11, a signal generator 12, a potential/ current measuring instrument 13, a printer 15, and the like, these being integrated in an enclosure 2, and can perform examination of the state of corrosion protection, judgment of insulation performance, and the like. The insulation performance of an insulation flange part 22 between the underground buried pipe 20 and an indoor pipe 21 can be examined by impressing a low-frequency exciting signal generated by the signal generator 12 on surfaces of the pipe 20 and on the pipe 21, separately, via two contacts 8, 9, and measuring by a magnetometric sensor 3 a magnetic field set up by an exciting current. To judge whether the state of cathodic protection is good or bad, the protective potential of the surface of the pipe 20 is measured by using the measuring instrument 13 or a protective current supplied from an Mg positive electrode etc., used for corrosion protection is measured. Results of the measurement and results of the insulation performance judgment can be printed and outputted from the printer 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathodic protection system for investigating an anticorrosion state of an object such as an underground pipe subjected to cathodic protection and collecting information for maintaining a good anticorrosion state. The present invention relates to a state measurement device.

[0002]

2. Description of the Related Art A metal pipe buried in the ground, for example, a supply pipe of city gas, is subjected to electrolytic protection. In order to supply city gas to customers, it is necessary to draw underground pipes into the building premises. In underground pipes such as city gas pipes, corrosion prevention is often performed using a magnesium (Mg) anode or the like, and the anticorrosion effect can be determined by potential measurement. In the part where the underground pipe for supplying city gas is drawn into the building site, the end of the underground pipe may be exposed on the ground or may come into contact with the reinforcing steel of the building. If the city gas supply pipe comes into contact with other metal parts, a sufficient anticorrosion potential may not be obtained, or a sacrificial anode material such as magnesium used for anticorrosion may be consumed intensely. In general, electrical insulation is applied to a portion where the object subjected to the cathodic protection comes into contact with another metal part or the like so that there is no adverse effect on the cathodic protection. However, there is a possibility that the performance of the electrical insulation is reduced with the passage of time or another metal part is brought into contact without being aware of the object of the cathodic protection. For this reason, in the supply pipes of city gas, etc., the corrosion protection potential and current in the building premises are regularly inspected, and if it is judged that the corrosion protection is bad, the underground buried part and indoor piping Insulation failure points between the parts are specified, and countermeasures are taken.

However, when it is judged from the potential that the anticorrosion state is defective, a skilled skill is required to investigate the cause.
There may be various cases such as the insulation state of the incoming pipe in the building, such as insulation failure such as a flange joint that supports the pipeline, insulation failure via a wall penetration or an overhead pipe support fitting for indoor piping, etc. It is. For this reason, the maintenance and management of the anticorrosion state includes measuring instruments for measuring the anticorrosion potential and anticorrosion current to determine whether the anticorrosion state is effective, and insulation resistance meters for investigating the cause of failure. Needs measuring equipment.

[0004]

As described above, in a gas supply piping system for a reinforced concrete structure such as a reinforced apartment house, a hospital, or a school, an indoor piping system is provided to protect a metal pipe buried underground from corrosion. And the underground buried section are electrically insulated, and effective measures are taken to prevent corrosion of underground pipes. However, there may be a case where the indoor piping section and the underground piping section are electrically short-circuited due to a change in a situation such as a modification of a building structure or a change in a piping system. Many types of measuring instruments are required to confirm that the corrosion prevention effect of underground metal pipes has deteriorated due to such changes in circumstances, to investigate and identify the cause of the deterioration, and to take countermeasures. And skilled skills are required.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an apparatus for measuring the state of anticorrosion, which can easily investigate the cause of poor anticorrosion of an object to be subjected to anticorrosion, such as an underground pipe.

[0006]

SUMMARY OF THE INVENTION The present invention is an apparatus for measuring the anticorrosion state of an object to be subjected to cathodic protection, comprising a signal generator for generating a low-frequency excitation signal, and a low-frequency signal from the signal generator. A magnetic sensor for measuring a magnetic field based on a low-frequency excitation signal on the surface of the object between the two contacts, a magnetic sensor for applying a frequency excitation signal to the surface of the object at an interval, A display for displaying a measurement result of a magnetic field measured by a sensor.

According to the present invention, the anti-corrosion state of an object to be subjected to cathodic protection is determined by applying a low-frequency excitation signal generated by a signal generator to the surface of the object and generating a magnetic field by a magnetic sensor. Measure and display. The low-frequency excitation signal generated by the signal generator is applied to the surface of the object at intervals by two contacts. If a current based on the low-frequency excitation signal flows between the two contacts, it is measured by the magnetic sensor. When the two contacts are brought into contact with the surface of the object with the insulating portion interposed therebetween, a current flows if the insulation is poor, and the magnetic sensor can measure the generation of a magnetic field based on the low-frequency excitation signal.

Further, in the present invention, a housing for accommodating the signal generator and the display, and an anticorrosion potential measurement using a reference electrode integrated with the housing and an anticorrosion current measurement can be performed. A potential / current measuring device to be displayed on the display device.

According to the present invention, the measurement of anticorrosion potential and the measurement of anticorrosion current using the reference electrode are possible, and the apparatus further includes a potential current measuring device for displaying the measurement result on a display. And it is possible to easily determine whether the anticorrosion state of the object is good. Since the potential / current measuring device, the signal generator, and the display are integrated in the housing, the insulation state can be easily checked while moving to many places.

The present invention also provides a housing for accommodating the signal generator and the display, an insulation performance judging unit integrated with the housing, and judging the insulation performance based on the measurement result. And a printing unit integrated with the housing and printing out the measurement result and the determination result of the insulation performance determining unit.

According to the present invention, the housing includes insulation performance determining means for determining whether the insulation performance is good or not based on the measurement result.
Since it further includes a printing unit that prints out the measurement result and the insulation performance determination result, the measurement result and the determination result can be recorded, and errors in investigation and determination can be eliminated. Since the insulation performance judging means and the printing means, the signal generator and the display are integrated in the casing, the insulation state can be easily checked while moving to many places.

[0012]

FIG. 1 shows a schematic electrical configuration of a cathodic protection state measuring apparatus 1 as one embodiment of the present invention. The cathodic protection state measuring device 1 of the present embodiment includes a housing 2
And a magnetic sensor 3 that can be attached to the housing 2 as needed. The magnetic sensor 3 has a coil for detecting a magnetic field at a distal end portion, and can detect a magnetic field generated by a current flowing on the surface of the object. As a magnetic sensor,
Those utilizing the magnetoresistance effect, the Hall effect, and the like can also be used. The housing 2 is provided with a sensor terminal 4 to which the magnetic sensor 3 can be connected. A signal corresponding to the strength of the magnetic field input from the magnetic sensor 3 via the sensor terminal 4 is subjected to signal processing such as amplification and conversion into a digital signal in a signal processing circuit 5. External terminals 6 and 7 are also provided on the housing 2, and two contacts 8 and 9 can be connected to the external terminals 6 and 7, respectively. The external terminals 6, 7 and the contacts 8, 9 can be switched to various functions.

A processing circuit 10 including a microcomputer and the like is provided in the housing 2, and a liquid crystal display (LC)
Various information can be displayed using the display 11 such as D). A signal generator 12 and a potential current measuring device 13 are further provided in the housing 2, and an output from the signal generator 12 and an input to the potential current measuring device 13 are externally connected via a switching circuit 14. Connected to terminals 6 and 7. A printer 15 serving as a printing unit for performing printout is also integrated in the housing 2, and a plurality of operation buttons 16 are provided on the surface of the housing 2. The processing circuit 10 switches the switching circuit 14 according to an input operation on the operation button 16, and connects the external terminals 6 and 7 to the output side of the signal generator 12 or the input side of the potential current measuring device 13. be able to. Further, information such as a measurement result can be displayed on the display device 11, and the measurement result and the like can be printed out from the printer 15.

The measurement by the magnetic sensor 3 is performed underground pipe 2
It can be suitably used for judging the quality of insulation performance at the insulation flange portion 22 between 0 and the indoor piping 21. A flange 20 a is provided at an end of the underground pipe 20, and is connected to a flange 21 a at an end of the indoor pipe 21 via an insulating packing 23. The fixing between the flanges 20a and 21a is performed by a plurality of sets of bolts 24 and nuts 25 arranged at intervals in the circumferential direction of the flanges 20a and 21a. The fastening portion between the bolt 24 and the nut 25 is also electrically insulated by the insulating cover 26 and the insulating washer 27, respectively. In FIG. 1, a set of bolts 24 and nuts 25 and the like are shown, and others are omitted.

If the insulating flange portion 22 has good insulating performance such as the insulating packing 23, the insulating cover 26, and the insulating washer 27, the plurality of bolts 24 are in an electrically floating state. The insulation state between the bolt 24 and one of the underground pipe 20 or the indoor pipe 21 can also be measured using, for example, an electric insulation resistance meter called a megger. However, when the insulation performance between the underground pipe 20 and the indoor pipe 21 is degraded, the insulation resistance meter may determine whether the insulation performance is degraded due to poor insulation of the insulation flange portion 22 or the insulation of other parts. It cannot be determined whether the performance is deteriorated.

FIG. 2 shows the reason why the position of defective insulation can be easily specified by the cathodic protection state measuring apparatus 1 of the present embodiment. FIG. 2A shows a state where a low-frequency excitation signal is applied to both sides of the insulating flange portion 22 via the contacts 8 and 9 as shown in FIG. FIG. 2 (b) shows the contact 8,
9 shows a distribution of an exciting current flowing on the surface of the underground pipe 20 or the indoor pipe 21 in a section having the contact position 9 at both ends. As shown in FIG. 2 (a), the exciting current 28 concentrates at the contact position of the contacts 8, 9 and expands in the circumferential direction of the underground pipe 20 or the indoor pipe 21 away from the contact position. The current density decreases. When the insulation performance at the insulation flange portion 22 is deteriorated, the current value increases as shown by the solid line in FIG. 2B, and when the insulation performance is good, the current value relatively decreases as shown by the phantom line. . When the insulation performance is degraded in portions other than the insulating flange portion 22, as shown in FIG. 2A, the current 29 flowing outside the section between the contact positions of the contacts 8, 9 increases. Magnetic sensor 3
Includes a coil that generates an electromotive force according to the intensity of the current flowing on the surface of the underground pipe 20 or the indoor pipe 21 that is the object, so that the current can be measured based on the detection output. The signal generator 12 generates a signal having a frequency of, for example, 40 Hz as the low-frequency excitation signal. Since the signal of this frequency is different from the frequency of the commercial AC power supply, noise removal and the like can be easily performed by the signal processing circuit 5 of FIG.

FIG. 3 shows a procedure for conducting an insulation determination survey using the cathodic protection state measuring device 1 of FIG. 1 in relation to the in-building service pipe 30 drawn into the customer building from the city gas pipe network. Show. The in-building entrance pipe 30 penetrates the support 31 of the building at the wall penetration portion 32 and is introduced into the building. The supporter 31 is made of reinforced concrete, in which rebars are embedded, and these rebars have a potential with respect to concrete, which is a noble potential compared with the potential with respect to iron. The in-building entrance pipe 30 is also supported in an insulated state by the aerial tube support 33 inside the building. After being electrically insulated by the insulating flange portion 22, it is connected to the indoor pipe 21. Indoor piping 21
Is supported by the overhead tube support portion 34. The aerial tube support 34 is not particularly electrically insulated, so that the indoor piping 21 is at a potential with respect to concrete like the supporter 31.

As shown by A in FIG.
In contrast, when the contacts 8 and 9 are brought into contact with the surface near the wall penetration portion 32 and the overhead tube support portion 33, and the low frequency excitation current is measured by the magnetic sensor 3 in the interval therebetween, the overhead tube It is possible to determine whether the insulation performance of the support portion 33 is good or not. If the insulation performance is degraded, a relatively large signal can be detected by the magnetic sensor 3. Even if the insulation performance is deteriorated on the side of the wall penetration portion 32, the magnetic sensor 3 cannot measure a sufficiently large exciting current unless the insulation performance of the overhead tube support portion 33 is deteriorated. When the magnetic sensor 3 detects the exciting current in the state shown in A, it can be determined that the insulation performance of the overhead tube support 33 has deteriorated.

FIG. 3B shows the state of investigation of the insulation performance between the overhead tube support 33 different from the overhead tube support 33 shown in FIG. A overhead tube support 3 shown in FIG.
3, the insulation performance deteriorates, and even though the exciting current may flow from this portion to the overhead tube support portion 33 of the portion B via the supporter 31, the insulation performance of the overhead tube support portion 33 of the portion B may occur. Is good, the entrance pipe 30 in the building between the contacts 8 and 9
In this case, the exciting current cannot be detected by the magnetic sensor 3. As shown in C, when the insulation performance of the insulation flange portion 22 is determined, the insulation flange portion 22
If the electrical insulation at the portion of the overhead tube support portion 33 is good, the magnetic sensor 3 does not detect the exciting current, and it can be determined that the insulation performance is good.

The insulation performance at the positions indicated by A, B, and C in FIG. 3 is confirmed by using a conventional electric insulation resistance meter. , The insulation resistance value becomes low at any of the positions A, B, and C, and it becomes impossible to specify an insulation failure portion. FIG. 3 shows a configuration in which the tips are simply brought into contact with the surface of the object as the contacts 8 and 9, but they are mechanically fixed to the surface of the object with clips or the like, Alternatively, it can be fixed to the surface of the object using an adhesive or the like.

FIG. 4 shows a procedure for checking the anticorrosion state of the service pipe 30 shown in FIG. The anticorrosion state can be investigated by measuring the anticorrosion potential and the anticorrosion current. In order to measure the anticorrosion potential, it is necessary to install a reference electrode 40 serving as a potential reference on the ground on the surface of the ground 41. One external terminal 7 is connected to the reference electrode 40, and one contact, for example, 8 is connected to the other external terminal 6, so that the contact 8 can measure the anticorrosion potential on the surface of the object. When insulation failure occurs in the in-building service pipe 30, it is understood that the anticorrosion potential on the surface deteriorates and the anticorrosion state of the underground pipe deteriorates. Alternatively, the corrosion prevention current supplied from the Mg anode 42 buried in the ground 41 as a magnetic anode to the service pipe 30 in the building also increases,
The anticorrosion state can also be determined from the measured value of the anticorrosion current. Generally, the in-building service pipe 30 is connected to a cast iron pipe forming a city gas pipe network in the ground 41 via a cast-steel insulation joint 43.

FIG. 5 shows a printout 5 in which the results of the investigation and measurement as shown in FIGS.
An example of 0 is shown. On the printout 50, measurement results relating to the anticorrosion performance measured as shown in FIG. 4, such as the anticorrosion potential measurement result 51 and the anticorrosion current measurement result 52, are printed, and as shown in FIG. The insulation determination result 53 based on the excitation current is also printed. Since the measurement result and the determination result are printed on the printout 50 in this manner, it is possible to eliminate a determination error and easily record the measurement result. In the cathodic protection state measuring apparatus 1 of the present embodiment, the necessary functions are integrated into the housing 2 or mounted on the housing 2 to improve portability. Inspection of anticorrosion performance and investigation of the cause of defective anticorrosion can be easily performed.

[0023]

As described above, according to the present invention, two contacts are brought into contact with each other so as to sandwich a portion that should be originally insulated by an object, a low-frequency excitation signal is applied, and By using the magnetic sensor to measure the magnetic field generated by the low-frequency excitation signal and displaying the measurement result on the display, the quality of the insulation performance can be easily determined.

Further, according to the present invention, the function required for confirming the anticorrosion state by performing the anticorrosion potential measurement and the anticorrosion current measurement is provided.
Since it is integrated in the same housing together with the function for judging the insulation performance, it is necessary to integrate necessary measuring instruments, from checking the anti-corrosion state to investigating the cause of defective anti-corrosion, to investigate the cause and take countermeasures. Convenience of later confirmation investigations can be achieved.

Further, according to the present invention, since a function of printing out a measurement result and a judgment result is provided, errors in investigation and judgment can be reduced. The components necessary for the insulation performance determination are integrated into the housing and can be easily carried, so that the quality of the insulation performance can be easily determined while moving to various places along the object. be able to.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic electrical configuration of a cathodic protection state measuring device 1 as one embodiment of the present invention.

FIG. 2 is a simplified side view and a graph showing the reason why the insulation performance of an insulating portion can be determined by the cathodic protection state measuring device of FIG. 1;

FIG. 3 is a diagram showing a procedure for conducting an insulation determination survey of the service pipe 30 in the building using the cathodic protection state measuring apparatus 1 of the embodiment of FIG. 1;

FIG. 4 is a diagram showing a procedure for investigating the state of the cathodic protection of the in-building service pipe 30 using the cathodic protection state measuring device 1 of the embodiment of FIG. 1;

5 is a printer 15 of the cathodic protection state measuring device 1 of FIG.
FIG. 7 is a diagram showing an example of a printout obtained from the embedment.

[Description of Signs] 1 Cathodic protection state measuring device 2 Housing 3 Magnetic sensor 4 Sensor terminal 5 Signal processing circuit 6, 7 External terminal 8, 9 Contact 10 Processing circuit 11 Display 12 Signal generator 13 Potential current measuring device 15 Printer Reference Signs List 20 Underground pipes 20a, 21a Flange 21 Indoor piping 22 Insulation flange part 23 Insulation packing 28 Excitation current 30 Building entrance pipe 31 Supporting work 32 Wall penetration part 33, 34 Overhead tube support part 40 Reference electrode 42 Mg anode 50 Printout 51 Corrosion protection potential measurement result 52 Corrosion protection current measurement result 53 Insulation judgment result

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G053 AA12 AB11 AB21 BA12 BA19 BA26 BC02 BC07 CA03 CA05 CA06 CB28 2G055 AA03 AA04 BA12 CA07 CA25 EA08 FA07 2G060 AA10 AE05 AF03 AF15 AG01 EA04 EA06 EB02 HC18 HD03

Claims (3)

[Claims] An apparatus for measuring the anticorrosion state of an object to be subjected to cathodic protection, comprising: a signal generator for generating a low-frequency excitation signal; and a low-frequency excitation signal from the signal generator. On the surface,
Two contacts applied at an interval, a magnetic sensor that measures the magnetic field based on the low-frequency excitation signal on the surface of the object between the two contacts, and a measurement result of the magnetic field measured by the magnetic sensor And a display device for performing the measurement. 2. A housing for accommodating the signal generator and the display, and a corrosion prevention potential measurement and a corrosion protection current measurement using a reference electrode integrated with the housing, and the measurement result is displayed on the display. 2. The apparatus according to claim 1, further comprising: a potential / current measuring device displayed on a vessel. 3. A housing accommodating the signal generator and the display, an insulation performance determining unit integrated with the housing, and judging insulation performance based on the measurement result. 3. The anticorrosion state measuring apparatus according to claim 1, further comprising a printing unit configured to print out the measurement result and the determination result of the insulation performance determining unit.