JP2002257792A - Pipe inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pipe inspection device capable of uniforming the sensitivity of each sensor within a sensor block and eliminating a sensor deteriorated in sensitivity. SOLUTION: The sensor block 2 having a substantially rectangular sectional shape is arranged along the inside of a pipe 1. The sensors 3 within the sensor block are arranged so that the tip parts of the sensors 3 have substantially the same distance from the inner wall of the pipe 1. Namely, denoted at 4 is a virtual circle concentric to the pipe 1, and all the sensors 3 are arranged so as to be substantially located on the virtual circle. The direction of each sensor 3 is preferably designed so that the longitudinal extension thereof passes through the center of the pipe 1. Accordingly, each sensor 3 is vertically opposed to the inner wall of the pipe 1, so that the sensitivity can be easily set to substantially the same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-pipe inspection apparatus that detects a defect in a pipe using a leakage magnetic flux inspection method, an eddy current inspection method, an ultrasonic inspection method, or the like.

[0002]

2. Description of the Related Art Pipes buried underground such as gas pipes include:
Although anti-corrosion devices are installed to prevent such corrosion, even during long periods of use, defects such as pitting may occur, especially on the outer surface. Holes may open in the wall. Even if a hole is made in the pipe wall, because the pipe is buried underground,
If the pressure inside the pipe is low, it is very unlikely that an accident such as a gas leak will occur immediately.However, such a state is not preferable, and defects such as pitting are small, and it is discovered before the hole is opened. Then, it is preferable to replace the piping in that portion. This necessity is particularly high in a main pipe having a large pipe diameter and a high pressure in the pipe.

One of the typical methods for detecting a defect in a pipe is to insert an in-pipe inspection device, commonly called an inspection pig (Inspection Pig), into the pipe, run the pipe, and use a sensor provided on the inspection pig. This is a method for detecting an abnormal part in the piping. As a method to run the inspection pig,
When the inspection distance is short, a method of pulling with a rope or the like is generally used. However, when the inspection distance is long, a method is used in which the vehicle travels by applying pressure from behind using a liquid or gas.

[0004] Ultrasonic flaw detection has also been put to practical use as a defect detection method for these inspection pigs. Various methods such as a flaw detection method have already been put to practical use.

FIG. 3 shows a schematic diagram of an inspection pig using a magnetic flaw detection method. The measuring device housing 12 for housing the measuring instruments in the inspection pig 11 is supported by a scraper cup 13 made of polyurethane or the like around its front and back, and runs through a pipe 24. The magnetizer 15 is provided in the measurement device housing 12.
A plurality of measuring device housings 22 are provided in the circumferential direction.
The magnetizer 15 holds a sensor block 17 via a copying mechanism 16, and moves along the inner wall of the pipe 14. A wire brush 18 is provided at the tip of the magnetizer 15 so that magnetism is transmitted to the pipe 14 and magnetized while following the pipe 14.

[0006] A plurality of sensors are housed in the sensor block 17, and each of the sensors detects a leakage magnetic flux of a minute portion in a circumferential direction in the pipe.

[0007]

FIG. 4 is a cross-sectional view of the conventional relationship between the sensor block 17 and the pipe 14 taken along a cross section of the pipe 14. As shown in FIG. Each sensor block 17 has a rectangular cross-section, and in the case of FIG. 4, four magnetic sensors 19 are provided in one sensor block. Therefore, as shown in the figure, the distance between the magnetic sensor 19 and the inner wall of the pipe 14 is small for the sensors at both ends of the sensor block 17 and large for the sensor at the center of the sensor block 17.

Therefore, the sensor at the center of the sensor block 17 and the sensors at both ends have different detection sensitivity for defects. Therefore, there is a problem that sensitivity adjustment is required for each sensor. In addition, the central sensor is far away from the tube wall, so that the sensitivity is reduced and there is a problem that the defect cannot be sufficiently detected.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has as its object to provide an in-pipe inspection apparatus in which the sensitivity of each sensor in a sensor block is made uniform and the sensor whose sensitivity decreases is eliminated. I do.

[0010]

A first means for solving the above-mentioned problem is an in-pipe inspection apparatus which travels in a pipe and detects a defect in the pipe, and has a sensor block having a plurality of sensors. The in-pipe inspection device (claim 1), wherein each sensor in the sensor block is arranged so that the distance between each sensor and the pipe wall is substantially equal during flaw detection. .

In this means, the sensors in the sensor block are arranged so that the distance between each sensor and the tube wall is substantially equal during the flaw detection.
The sensitivity of each sensor can be made uniform. Note that “substantially equal” means that a slight difference in the distance is allowed as long as the variation in the sensitivity of the sensor due to the variation in the distance between each sensor and the tube wall is within a design tolerance. It is the purpose.

A second means for solving the above-mentioned problem is as follows.
The first means, wherein the surface of the sensor block facing the pipe wall is a curved surface substantially concentric with the inner wall of the pipe (claim 2).

In this means, the surface of the sensor block facing the pipe wall is a curved surface substantially concentric with the inner wall of the pipe, that is, a cylindrical surface. When the first means is adopted, the distance between each sensor and the inner wall of the pipe can be reduced. Therefore, the sensitivity of the sensor can be increased. Note that “substantially concentric” means that the distance between the sensor and the pipe wall is within a range allowable in terms of the sensitivity of the sensor when the sensor is arranged so as to realize the first means. Concentric.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows Embodiment 1 of the present invention.
It is a figure showing the sensor and the sensor block of the example in-pipe inspection device, and is a sectional view cut along the section of piping.
A sensor block 2 having a substantially rectangular cross section is arranged along the inner periphery of the pipe 1. The arrangement of the sensor 3 in the sensor block 2 is different from that shown in FIG. The distance between the section and the inner wall of the pipe 1 is made substantially equal.

That is, in FIG. 1, reference numeral 4 denotes an imaginary circle concentric with the pipe 1, but the sensors 3 are arranged so that the tips of all the sensors 3 are substantially on this imaginary circle. In addition, it is preferable that the direction of each sensor 3 is designed so that the extension line in the length direction is located at the center of the pipe 1. Thereby, any of the sensors 3 is vertically opposed to the inner wall of the pipe 1, and it is easy to make the sensitivity close to the same.

FIG. 2 is a view showing a sensor and a sensor block of an in-pipe inspection apparatus as another example of the embodiment of the present invention, and is a sectional view taken along a section of the pipe. FIG.
, The same components as those shown in FIG. 1 are denoted by the same reference numerals.

In the embodiment shown in FIG. 2, the surface of the sensor block 2 facing the pipe 1 is cylindrical.
The center is substantially equal to the center of the pipe 1. Figure 1
2 and FIG. 2, in FIG. 2, by making the surface of the sensor block 2 facing the pipe 1 cylindrical, the sensor block 2 can be made closer to the inner wall of the pipe 1.

Thus, the distance between each sensor 3 and the inner wall of the pipe (the lift-off of the sensor) can be reduced, and the sensitivity of each sensor 3 can be increased accordingly.

In the above description, the magnetic flaw detection method has been described as an example. However, the same applies to the eddy current flaw detection method, the ultrasonic flaw detection method, and the like. By doing so, it is possible to reduce the variation in sensitivity between the sensors, and also to reduce the lift-off, thereby increasing the sensitivity of each sensor.

[0020]

As described above, in the invention according to the first aspect of the present invention, since the distance between each sensor and the tube wall is substantially equal during the flaw detection, The sensitivity of the sensor can be made uniform.

In the invention according to the second aspect, the distance between each sensor and the inner wall of the pipe can be shortened.
It is possible to increase the sensitivity of the sensor.

[Brief description of the drawings]

FIG. 1 is a diagram showing a sensor and a sensor block of an in-pipe inspection apparatus which is an example of an embodiment of the present invention.

FIG. 2 is a diagram showing a sensor and a sensor block of an in-pipe inspection apparatus as another example of the embodiment of the present invention.

FIG. 3 is a diagram showing an outline of an inspection pig using a magnetic flaw detection method.

FIG. 4 is a diagram showing a positional relationship between a conventional sensor block and piping.

[Explanation of symbols]

 1. Piping 2. Sensor block 3. Sensor 4. Virtual circle

Continued on the front page F term (reference) 2G047 AA07 AB01 BC07 DB18 GA20 GB18 GJ08 2G053 AA11 AB21 AB22 BA12 DB04 DB24

Claims (2)

[The claims] An in-pipe inspection device that travels in a pipe and detects a defect in the pipe, comprising a sensor block having a plurality of sensors, wherein each sensor in the sensor block includes a sensor and a pipe. An in-pipe inspection device, wherein the inspection device is arranged so that a distance from the wall is substantially equal during the flaw detection. 2. The in-pipe inspection apparatus according to claim 1, wherein a surface of the sensor block facing the pipe wall is a curved surface substantially concentric with the inner wall of the pipe. .