KR101747051B1 - Nondestructive inspection method for pipe to correct residual magnetization effect - Google Patents

Abstract

The present invention relates to a method for acquiring a magnetic leakage signal from a sensor of a piping inspection apparatus for inspecting a pipe using a magnetic field, comprising the steps of: acquiring a magnetic leakage signal; acquiring a level of the magnetic leakage signal as background intensity; A non-destructive inspection method of a pipe for correcting residual magnetization influences, comprising a maintenance cost calculation step of calculating a maintenance cost based on the stored reference strength and the background intensity, and a correction step of correcting the magnetic leakage signal using a maintenance cost to provide.

Description

[0001] The present invention relates to a non-destructive inspection method for pipes,

The present invention relates to a nondestructive inspection method for piping that corrects residual magnetization effects.

In order to prevent accidents caused by corrosion of piping, the condition of piping should be periodically inspected and replaced. A method of inspecting a pipe by inserting a pipe inspecting device (such as a pig) into the pipe is used as a method of nondestructive inspection of the pipe.

There is a method of using a magnetic field such as magnetic flux leakage (MFL) and eddy current testing (ECT) in a method of inspecting a pipe. Ultrasonic Testing (UT) (Electromagnetic-acoustic transducer) are also used.

On the other hand, when a magnetic field is applied to a magnetic body, the atoms in the magnetic body are aligned in a certain direction and magnetization occurs. Even if the magnetic field is removed according to the magnetic body, a part of the magnetic body is kept magnetized. When a magnetic pipe is inspected by applying a magnetic field to the same principle, residual magnetization is formed in the pipe after the inspection is completed.

KR 10-0638997 B1

An object of an embodiment of the present invention is to provide an inspection method that corrects the influence of residual magnetization remaining on a pipeline to be inspected to more accurately perform nondestructive inspection of piping.

Further, in the process of inspecting the pipe using the magnetic field, the level of the magnetic leakage signal obtained from the sensor of the pipe inspection apparatus is acquired as the background intensity, and the magnetic leakage signal is corrected To thereby provide a non-destructive inspection method for a pipe that corrects the influence of residual magnetization.

It is another object of the present invention to provide a nondestructive inspection method for a pipeline which can acquire an inspection history of a current pipeline by comparing the obtained background intensity with previously stored test history-background intensity information.

A nondestructive inspection method for a pipe for correcting residual magnetization influences according to an embodiment of the present invention includes a magnetic leakage signal acquisition step of acquiring a magnetic leakage signal from a sensor of a pipe inspection apparatus for inspecting a pipe using a magnetic field, A background intensity obtaining step of obtaining a level of a signal as a background intensity, a correction ratio calculating step of calculating a correction ratio based on the reference strength of the pipe and the background intensity, and a correction step of correcting the magnetic leakage signal using a maintenance ratio And a correction step.

Also, the background intensity acquiring step may include comparing the magnitude of the magnetic leakage signal with a threshold range, and when the magnitude of the magnetic leakage signal is maintained for a predetermined period without exceeding the limit range, And a background intensity calculating step of calculating the level of the magnetic leakage signal as the background intensity.

Further, the background intensity acquiring step may further include a level change determining step of determining whether the magnitude of the magnetic leakage signal is recovered within the limit range when the magnitude of the magnetic leakage signal is out of the limit range, The background intensity calculation step is performed.

Further, the background intensity acquiring step further includes a step of setting a new limit range and continuing to the background intensity calculating step when the magnitude of the magnetic leakage signal is not recovered within the predetermined range for the predetermined period.

The method further includes an inspection history acquiring step of acquiring an inspection history of the pipeline inspected by the pipeline inspection apparatus by collating the background intensity with the previously stored inspection history-background intensity data.

The limit range is a range between a lower limit value smaller than the level of the magnetic leakage signal and an upper limit value larger than a level of the magnetic leakage signal.

Also, the maintenance ratio is a ratio of the reference intensity divided by the background intensity, and the correction step changes the magnitude of the magnetic leakage signal by the amount corresponding to the maintenance ratio to generate a corrected magnetic leakage signal.

The features and advantages of the present invention will become more apparent from the following detailed description based on the accompanying drawings.

Prior to that, terms and words used in the present specification and claims should not be construed in a conventional and dictionary sense, and the inventor may properly define the concept of the term in order to best explain its invention It should be construed as meaning and concept consistent with the technical idea of the present invention.

According to the embodiment of the present invention, there is an advantage that the nondestructive inspection of the pipe can be more accurately performed by correcting the magnetic leakage signal reflecting the influence of the residual magnetization remaining in the pipe.

Further, in the process of inspecting the pipe using the magnetic field, the level of the magnetic leakage signal obtained from the sensor of the pipe inspection apparatus is acquired as the background intensity, and the magnetic leakage signal is corrected Therefore, there is an advantage that the influence of the residual magnetization can be corrected even when the inspection history of the pipe is unknown.

In addition, there is an advantage that the obtained background intensity can be compared with the previously stored test history-background intensity information to acquire the test history of the current inspection target pipe.

1 is a view showing a state in which a pipe inspection apparatus performs nondestructive inspection of a pipe using a magnetic field.
2 is a graph showing a magnetic leakage signal obtained from the sensor of the pipe inspection apparatus of FIG.
3 is a graph showing the relationship between the magnetic field applied to the pipe by the pipe inspection apparatus and the magnetic flux density measured by the sensor.
4 is a flowchart illustrating an operation of a nondestructive inspection method of a pipe for correcting the residual magnetization effect according to an embodiment of the present invention.
5 is a view showing a magnetic leakage signal outputted at the piping line and piping inspection.
6 is a flowchart showing details of the background strength acquisition step (S120).

BRIEF DESCRIPTION OF THE DRAWINGS The objects, particular advantages and novel features of one embodiment of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings and the preferred embodiments thereof. It should be noted that, in the present specification, the reference numerals are added to the constituent elements of the drawings, and the same constituent elements are assigned the same number as much as possible even if they are displayed on different drawings. Also, the terms "one side," " first, "" first," " second, "and the like are used to distinguish one element from another, no. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description of the present invention, a detailed description of known arts which may unnecessarily obscure the gist of an embodiment of the present invention will be omitted.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing a state in which the pipe inspection apparatus 20 performs a non-destructive inspection of the pipe 10 by using a magnetic field. FIG. 2 is a view showing a magnetic leakage obtained by the sensor 21 of the pipe inspection apparatus 20 of FIG. Fig.

The pipe inspection apparatus 20 is a device for nondestructively inspecting a pipe 10 while traveling inside the pipe 10 and is provided with a pig (PIG) running on the basis of the fluid pressure inside the pipe 10, (E.g., a motor, a battery, a wheel, or the like) that travels in the piping 10, and the like.

The pipe inspection apparatus 20 applies a magnetic field generated by the magnetic field generating unit 23 to the pipe 10 and detects a magnetic flux leaked from a portion of the defect 11 existing in the pipe 10 Flux) by using the sensor 21, and processes the magnetic leakage signal output from the sensor 21 through the information processing unit 22. [0050] Also, the pipe inspection apparatus 20 can measure the distance that the pipe 10 travels by using an odometer (not shown).

As shown in FIG. 1, when the pipe inspection apparatus 20 proceeds in the traveling direction and inspects the pipe 10 in a non-destructive manner, the pipe 10 is inspected at the position where the defect 11 exists in the pipe 10, A magnitude variation M1 of the magnetic leakage signal occurs.

On the other hand, in the nondestructive inspection using a magnetic field, even after the pipe inspection apparatus 20 passes, some of the atoms constituting the pipe 10 are aligned along the magnetic field so that the residual magnetization exists in the pipe 10 . The residual magnetization of the pipe 10 causes the pipe inspecting apparatus 20 to weaken the magnetic field applied to the pipe 10 and eventually causes the magnetic leakage signal It affects size.

2 is a graph showing the results of repeated inspection of the same defects 11 present in the pipe 10 having the same specifications (material, thickness, diameter, etc.) using the pipe inspection apparatus 20. Fig.

2, there is no residual magnetization in the pipe 10 in which the non-destructive inspection using the magnetic field is not performed (no inspection history). When the non-destructive inspection using the magnetic field is performed on the pipe 10 having no inspection history, a magnitude variation of the magnetic leakage signal is generated by M1 as shown in FIG. In the pipe 10, residual magnetization due to nondestructive inspection using a magnetic field is present.

The residual magnetization exists in the pipe 10 in which the nondestructive inspection using the magnetic field is once performed (the test history is once). When the nondestructive inspection using the magnetic field is performed on the pipe 10 having this inspection history once, the magnitude variation of the magnetic leakage signal is generated by M2 as shown in Fig. By the residual magnetization of the pipe 10, the magnitude variation of the magnetic leakage signal is reduced (i.e., from M1 to M2), and the level of the magnetic leakage signal is reduced (i.e., from L1 to L2). In the pipe 10, the residual magnetization due to the nondestructive inspection using a magnetic field is stronger.

The pipe 10 (twice the inspection history) in which the nondestructive inspection using the magnetic field is performed twice has a stronger residual magnetization than the residual magnetization of the pipe 10 whose inspection history is once. When the nondestructive inspection using the magnetic field is performed on the pipe 10 having the inspection history twice, the magnitude variation of the magnetic leakage signal is generated by M3 as shown in FIG. Since the residual magnetization of the pipe 10 is strong, the magnitude variation of the magnetic leakage signal is reduced (i.e., from M2 to M3), and the level of the magnetic leakage signal is reduced (i.e., from L2 to L3). In the pipe 10, the residual magnetization due to the nondestructive inspection using a magnetic field is stronger.

The difference between the magnetic leakage signal magnitude fluctuation amount M1 that inspects the piping 10 having no test history and the magnetic leak signal magnitude variation amount M2 that inspects the piping 10 whose inspection history is one time, Leakage signal magnitude variation M3 in which the magnetic leakage signal magnitude variation magnitude M2 inspected by the inspection history 10 and the magnitude of the magnetic leakage signal magnitude variation M3 inspected in the pipe 10 whose inspection history is two magnitudes.

When the difference between the level L1 of the magnetic leakage signal inspected on the pipe 10 having no inspection history and the level L2 of the magnetic leakage signal inspected on the pipe 10 having the inspection history of one, Is greater than the difference between the level (L2) of the magnetic leakage signal inspected by the reed pipe (10) and the level (L3) of the magnetic leakage signal obtained by inspecting the pipe (10)

The greater the test history, the smaller the magnitude variation of the magnetic leakage signal and the difference in the level of the magnetic leakage signal, and finally the magnitude variation of the magnetic leakage signal and the level of the magnetic leakage signal converge to a constant value. This is because, when the magnetic field of the same intensity is used, the intensity of the residual magnetization remaining in the pipe 10 converges to a certain value.

As described above, even when the same defect 11 is inspected, a phenomenon that the magnitude variation of the magnetic leakage signal gradually decreases due to the influence of the residual magnetization as the inspection history of the pipe 10 increases. As described above, when the size variation of the magnetic leakage signal is reduced, it is difficult to accurately determine the size of the defect 11 or existence of the defect 11 in the inspection of the pipe 10.

This phenomenon can be explained with reference to Fig. 3 is a graph showing the relationship between the magnetic field applied to the pipe 10 by the pipe inspection apparatus 20 and the magnetic flux density measured by the sensor 21. As shown in FIG.

Referring to FIG. 3, when the pipe inspection apparatus 20 applies a magnetic field-H1 to the pipe 10 having no residual magnetization, the magnetic flux density-B1 is measured by the sensor 21. On the other hand, when the pipe inspection apparatus 20 applies the magnetic field -H1 to the pipe 10 having residual magnetization, the magnetic field-H2 is applied to the pipe 10 by the magnetic field generated by the residual magnetized region of the pipe 10 And the magnetic flux density -B2 is measured in the sensor 21. [ Therefore, the magnitude of the magnetic leakage signal measured by the sensor 21 at the time of inspecting the pipe 10 with residual magnetization is the magnitude of the magnetic leakage signal measured by the sensor 21 at the time of inspecting the pipe 10 having no residual magnetization It is smaller than the size. If the magnitude of the magnetic leakage signal is small, it is difficult to judge the presence of the fine defects 11, and it is difficult to accurately determine the size of the defects 11. By this process, the residual magnetization of the pipe 10 has a negative influence on the nondestructive inspection using the magnetic field.

4 is a flowchart showing the operation of the nondestructive inspection method of the pipe 10 for correcting the residual magnetization effect according to an embodiment of the present invention.

The nondestructive inspection method of the pipe 10 for correcting the influence of the residual magnetization according to the embodiment of the present invention is a method of detecting the magnetic leakage signal from the sensor 21 of the pipe inspection apparatus 20 for inspecting the pipe 10 using the magnetic field, A background strength acquisition step S120 for acquiring the level of the magnetic leakage signal as a background intensity, a calculation step for calculating a maintenance ratio based on the reference strength and the background intensity stored in advance in the pipeline 10 And a correction step (S140) of correcting the self-leakage signal using the maintenance cost.

A pipe inspection apparatus 20 for inspecting a pipe 10 using a magnetic field in a magnetic leakage signal acquisition step S110 applies a magnetic field to the pipe 10 and acquires a magnetic leakage signal output from the sensor 21 do. A plurality of sensors 21 may exist for inspecting the inner circumferential surface of the pipe 10, thereby obtaining a plurality of magnetic leakage signals, respectively. As shown in FIG. 2, the magnitude of the magnetic leakage signal varies as the magnetic leakage signal passes through the defect 11. FIG.

In the background intensity acquisition step (S120), the background intensity is obtained from the magnetic leakage signal acquired in the magnetic leakage signal acquisition step. The background intensity refers to the level (Level) of the magnetic leakage signal output by the sensor 21. The level of the magnetic leakage signal refers to the magnitude of the magnetic leakage signal output from the sensor 21 at the position where the defect 11 does not exist in the piping 10 and the magnetic leakage signal for a predetermined period (time or distance) The size of the signal can be averaged.

For example, as shown in Fig. 2, when inspecting a pipe 10 having no test history, the background intensity becomes the level L1 of the magnetic leakage signal, and the pipe 10 having the test history once is inspected The background intensity at the time of the self-leakage signal becomes the level L2 of the magnetic leakage signal. Thus, different background intensities are obtained depending on the test history, and the acquired background intensities are used to correct the influence of the residual magnetization.

The information processing unit 22 of the pipe inspection apparatus 20 compares the background intensity acquired while inspecting the pipe 10 with the previously stored reference intensity to calculate the maintenance cost. The reference intensity is a value stored in the memory of the information processing unit 22 and is information already input before starting the inspection of the pipe 10.

The reference strength is measured using a pipe 10 having the same specifications (material, thickness, inner diameter, etc.) as the pipe 10 to be inspected. The same spec pipe 10 having no test history is inspected by the same pipe inspecting apparatus 20 and the level of the magnetic leakage signal is obtained as the reference strength in the same manner as the above-mentioned background strength obtaining step. For example, as shown in Fig. 2, the level L1 of the magnetic leakage signal obtained by inspecting the piping 10 having no inspection history becomes the reference strength.

The maintenance cost can be defined as 'the ratio of the reference intensity to the background intensity'. Alternatively, the maintenance cost may be defined as the 'ratio of the reference intensity divided by the background intensity times the constant'. This maintenance ratio is obtained by dividing the variation amount M2 of the magnetic leakage signal obtained at the position of the defect 11 of the pipe 10 having the test history by the magnetic leak signal M2 obtained at the position of the defect 11 of the pipe 10, The amount of change M1 is set to be large.

In the correction step (S140), the information processing unit (22) of the pipe inspection apparatus (20) corrects the magnetic leakage signal obtained from the sensor (21) using the maintenance ratio. That is, the information processing unit 22 changes the magnitude of the magnetic leakage signal by the amount corresponding to the maintenance ratio, and generates a corrected magnetic leakage signal.

By changing the magnitude of the magnetic leakage signal obtained by the sensor 21 by the amount corresponding to the maintenance ratio, the influence of the residual magnetization in the magnetic leakage signal is corrected. For example, when the reference intensity is 100, and the background intensity obtained at the time of inspection of the pipe 10 is 80, if the magnetic leakage signal is changed by the maintenance ratio (100/80), the level of the corrected magnetic leakage signal is 100 And the amount of magnitude variation of the magnetic leakage signal also increases proportionally when passing through the defect 11. [

On the other hand, the information processing unit 22 may output the magnitude of the magnetic leakage signal by changing the magnitude of the magnetic leakage signal to correspond to the maintenance ratio, or may store the corrected magnetic leakage signal graph in the memory.

As described above, the nondestructive inspection method of the pipe 10 for correcting the influence of the residual magnetization according to the embodiment of the present invention uses the background intensity obtained at the time of inspection of the pipe 10 to be inspected and the previously stored reference intensity And changes the magnitude of the magnetic leakage signal output by the sensor 21 by the maintenance ratio (reference intensity / background intensity).

In this way, the magnetic leakage signal can be obtained which can more clearly determine the presence or absence of the defect (11), so that the nondestructive inspection of the pipe (10) can be more accurately performed.

The level of the magnetic leakage signal obtained from the sensor 21 of the pipe inspecting apparatus 20 can be set to be the same as or higher than the level of the magnetic leakage signal obtained when the inspection history of the pipe 10 is unknown (i.e., the residual magnetization is present or the strength of the residual magnetization is unknown) (Base intensity / background intensity) compared with the reference intensity previously acquired and corrects the magnetic leakage signal, there is an advantage that the influence of the residual magnetization can be corrected.

Hereinafter, the background intensity obtaining step (S120) according to an embodiment of the present invention will be described in more detail.

FIG. 5 is a view showing a magnetic leakage signal outputted at the time of inspecting the piping line 12 and the piping 10, and FIG. 6 is a flowchart showing details of the background intensity obtaining step (S120).

As shown in Fig. 5, a plurality of pipes 10 are connected in series to constitute a pipe line 12. [ A pipe inspection apparatus 20 passes through a piping line 12 and inspects a plurality of piping 10 so that a magnetic leakage signal obtained at the sensor 21 is shown below the piping 10.

On the other hand, if any one of the pipelines 10 in the piping line 12 has an abnormality, only the piping 10 is replaced with a new piping 10 to repair the piping line 12. 5, a new pipe 10 can be included in the pipe 10 line, and the old pipe 10, such as the pipe 10, can remain in the pipe 10 line have.

Therefore, one piping line 12 can include a pipe 10 having a different inspection history. For example, the piping 10 and the piping 10 in FIG. 5 have a single inspection history, the piping 10 and the piping 10 are newly replaced piping 10, 10) Then the test history may be more than 2 times.

6, the background intensity acquisition step S120 includes comparing a magnitude of the magnetic leakage signal with a threshold range (S210), and comparing the magnitude of the magnetic leakage signal with a threshold range (S210) And a background intensity calculating step (S240) of calculating the level LB of the magnetic leakage signal during the predetermined period t1 as the background intensity, if it is maintained for a predetermined period t1.

The magnitude of the magnetic leakage signal varies in the position where the defect 11 exists and the level of the magnetic leakage signal changes when the pipe inspection apparatus 20 enters the pipe 10 having the different inspection histories. For example, the magnetic leakage signal of B in the pipe 10 A of FIG. 5 is the same level, and the magnetic leakage signal corresponding to the pipe 10 B has the size variation MB at the position of the defect 11 , The level of the magnetic leakage signal changes from the line 10B to the pipe 10C (that is, from LB to LC).

In order to acquire the background intensity (S120), it is necessary to acquire the level of the magnetic leakage signal in a state in which no such magnitude change occurs. Therefore, the magnitude of the magnetic leakage signal is compared with the limit range (S210).

The limit range can be set to a range between a lower limit value V1 that is smaller than the level of the magnetic leakage signal and an upper limit value V2 that is larger than the level of the magnetic leakage signal. This means that the fluctuation of the magnetic leakage signal within the limit range is considered noise, and the limit range is set based on the level, which is the average value of the magnetic leakage signal during a certain period (time or distance) (t1 in FIG. 5).

When the magnitude of the magnetic leakage signal is maintained for a predetermined period (see t1 in FIG. 5) without exceeding the limit range in the background intensity calculation step S240, the level of the magnetic leakage signal during the predetermined period t1 LB in Fig. 5) as the background intensity. This is because there is no defect 11 and there is no level change during a certain period t1, so the level of the magnetic leakage signal is set as the background intensity.

The step of obtaining the background strength (S120) further includes a level change determination step (S220) of determining whether the magnitude of the magnetic leakage signal is recovered to a limit range when the magnitude of the magnetic leakage signal is out of the limit range, If the size is recovered within the limit range, the background intensity calculation step S240 is performed.

The level change determination step S220 determines whether the magnitude of the magnetic leakage signal that has already exceeded the limit range falls within a predetermined range within a certain period of time (see t2 in FIG. 5) ) Is a change in the recognition level.

If the magnitude of the magnetic leakage signal is recovered within the limit range, it is determined that the magnitude of the magnetic leakage signal is due to the defect 11, and the background intensity calculation step S240 is performed. For example, in the graph of the magnetic leakage signal corresponding to the pipe 10 B in FIG. 5, when the magnetic leakage signal falls below the lower limit value V1 of the limit range, Restored within range. In this case, since the magnitude of the magnetic leakage signal has changed due to the defect 11 of the pipe 10, the process proceeds directly to the background strength calculating step S240.

In the case where the magnitude of the magnetic leakage signal is not recovered within a predetermined range within a predetermined period, the step of acquiring background strength (S120) may include setting a new limit range and setting a limit range setting step (S230) .

The limit range setting step S230 is a step of determining that the magnitude of the magnetic leakage signal is not recovered within a predetermined range for a predetermined period of time when it is entered into the pipe 10 having a different test history and setting a new limit range . For example, when the magnetic leakage signal obtained at the boundary between the pipe 10B and the pipe 10C shown in FIG. 5 shows a magnetic leakage signal exceeding the upper limit value V2 for a predetermined period t2, It is not recovered within the limit range. In this case, a new limit range (new upper limit value NV2 and new lower limit value NV1) is set in the limit range setting step S230.

The new limit range is set to a new lower limit value NV1 that is a value smaller than the level of the magnetic leakage signal by a predetermined value in the same manner as the existing limit range and a value larger by a certain value than the level of the magnetic leakage signal is set as a new upper limit Value (NV2). Or a value smaller by a certain ratio of the magnetic leakage signal level to a new lower limit value NV1 and a value larger than the level of the magnetic leakage signal by a new upper limit value NV2 Can be determined.

In the case where the limit range is determined by the ratio to the magnetic leakage signal level, since the level of the magnetic leakage signal is higher, the noise is also often included, so that the limit range is widened proportionally so that the accuracy of the non- There is an advantage.

When the limit range setting step S230 is performed, the background intensity calculating step S240 is performed. Therefore, if the above-described steps are performed, the background intensity can be obtained from the magnetic leakage signal even if the piping 10 having the different inspection history is mixed in the piping line 12 or the defect 11 is measured in the piping 10 .

Another method of determining whether there is a defect 11 in the piping 10 or a change in level due to entering the piping 10 having a different inspection history will be described below in the background strength acquisition step S120.

The pipe inspection apparatus 20 includes a plurality of sensors 21 in the outer circumferential direction of the pipe inspection apparatus 20 for inspecting the inner circumferential surface of the pipe 10. Therefore, the magnetic leakage signal output from the sensor 21 passing through the region where the defect 11 exists in the pipe 10 has a magnitude variation like a magnetic leakage signal corresponding to the pipe 10 B in FIG. 5, The magnetic leakage signal output from the sensor 21 passing through another region where the defects 11 are absent will be within the limit range.

Therefore, it is determined whether only a part of the magnetic leakage signals out of the plurality of magnetic leakage signals exceeds the limit range (S310). If only some of the magnetic leakage signals deviate from the limit range, the pipe inspection apparatus 20 passes through the defect 11 And the background intensity can be obtained from the magnetic leakage signal that does not exceed the limit range (S320).

If all the magnetic leakage signals out of the plurality of magnetic leakage signals exceed the limit range, it is determined whether the magnetic leakage signal is recovered within a predetermined range for a predetermined period of time (S330). If the magnetic leakage signal is not recovered, It is determined that the pipe 10 has entered the pipe 10 and a new limit range can be set (S340). Once the new limit range has been set, it may lead to step 320 of acquiring background intensity in the magnetic leakage signal.

If the pipe inspection apparatus 20 passes through the defect 11 of the pipe 10 or enters the pipe 10 different from the inspection history by carrying out the detailed steps of the background strength acquisition step S120 described above The background intensity can be obtained from the leakage magnetic flux signal. Even if the pipelines 10 having different test histories are mixed in one piping line 12, the accuracy of the inspection of the piping 10 is not deteriorated and the leakage magnetic flux signal There is an advantage in that even if the level of the leakage magnetic flux signal changes, the inspection can be continued in accordance with the changed level.

The nondestructive inspection method of the pipe 10 for correcting the residual magnetization influences according to the embodiment of the present invention compares the background intensity with the previously stored test history-background strength data, (S150) of acquiring an inspection history of the inspection apparatus (10).

The inspection history-background intensity data is generated by measuring the background intensity while repeatedly inspecting the pipe 10 having the same specifications (material, thickness, inner diameter, etc.) as the inspection target pipe 10 by the pipe inspection device 20. The inspection history-background intensity data thus generated is stored in the memory of the pipe inspection apparatus 20 before inspection of the pipe line 12.

The test history-background intensity data can be configured illustratively as shown in Table 1 below.

Test history Background intensity none 100 1 time 80 Episode 2 68 3rd time 62 More than 4 times 58

For example, when the pipeline 10 having the background strength of 100, the pipeline 10 having the background history of 1, and the background strength of 80 when the pipeline 10 having no test history is inspected, (10) having a background strength of 68 and a background strength of 62 when the inspection of the pipe (10) having the inspection history of 3 times and a pipe inspection (10) having the inspection history of 4 or more The background intensity is 58.

When the pipeline inspection apparatus 20 inspects the pipeline 12 and the background intensity of the first pipeline 10 is measured as 81, the inspection history-background intensity data and the background intensity are checked against each other and the existing inspection history of the first pipeline 10 Is a one-time piping (10), and it can be seen that the inspection history is twice when the present inspection is completed. In the same manner, when the background intensity of the fifth pipe 10 is measured as 67, the inspection history-background strength data is compared with the background intensity, and the pipe 10 having the existing inspection history of the fifth pipe 10 is twice, When the current inspection is completed, the inspection history becomes 3 times.

In this way, an inspection history of the piping 10 constituting the piping line 12 is generated in order of the piping 10 (or in relation to the distance information received from the odometer) while checking the piping line 12 . The inspection history of the pipes 10 thus generated can be utilized variously. Since the inspection of the piping 10 is performed with a certain period (for example, every 5 years), the piping 10 having a large inspection history can be estimated as the old piping 10, It is possible to grasp the number of the pipelines 10 to be replaced as a whole, which is helpful for planning of the budget and construction schedule.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the same is by way of illustration and example only and is not to be construed as limiting the present invention. It is obvious that the modification and the modification are possible.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

10: Piping
11: Defects
12: piping line
20: Piping inspection system
21: Sensor
22: Information processing unit
23: magnetic field generating unit

Claims (7)

A magnetic leakage signal obtaining step of obtaining a magnetic leakage signal of a pipe which does not know an inspection history from a sensor of a pipe inspection apparatus for inspecting a pipe using a magnetic field;
A background intensity obtaining step of obtaining the level of the magnetic leakage signal as a background intensity;
A maintenance cost calculating step of calculating a maintenance cost based on the reference strength measured in advance and the background strength measured from a pipe having no test history having the same specification as the pipe; And
And correcting the magnetic leakage signal by using the calculated maintenance ratio.
The method according to claim 1,
The background intensity acquisition step
Comparing a magnitude of the magnetic leakage signal with a threshold range; And
And a background intensity calculating step of calculating a level of the magnetic leakage signal for the predetermined period as a background intensity when the magnitude of the magnetic leakage signal is maintained for a predetermined period without exceeding the limit range, Nondestructive inspection method of pipe to be corrected.
The method of claim 2,
The background intensity acquisition step
Further comprising a level change determining step of determining whether the magnitude of the magnetic leakage signal is restored to within the limit range when the magnitude of the magnetic leakage signal is out of the limit range,
And correcting the residual magnetization effect leading to the background intensity calculation step when the magnitude of the magnetic leakage signal is recovered within the limit range.
The method of claim 3,
The background intensity acquisition step
A non-destruction of a pipe for correcting the residual magnetization effect further including setting a new limit range and setting the limit range to the background intensity calculation step when the magnitude of the magnetic leakage signal is not recovered for a predetermined period of time within the limit range method of inspection.
The method according to claim 1,
Further comprising a test history obtaining step of obtaining the test history of the pipeline inspected by the pipeline inspection device by collating the background intensity obtained from the pipeline that does not know the test history with the previously stored test history- Nondestructive inspection method of pipe to compensate magnetization effect.
The method of claim 2,
The limit range
Which is a range between a lower limit value smaller than the level of the magnetic leakage signal and an upper limit value larger than the level of the magnetic leakage signal.
The method according to claim 1,
The maintenance cost
'The reference intensity divided by the background intensity'
The correction step
Wherein the magnitude of the magnetic leakage signal is changed by the magnitude corresponding to the maintenance ratio to generate a corrected magnetic leakage signal.

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