JPH08201347A - Tube flaw detecting device - Google Patents

Abstract

PURPOSE: To uniformly detect flaws by inserting a probe into a flaw inspected pipe, arranging multiple eddy current flaw detecting sensors into the array shape in the peripheral direction of the probe while the coil face is faced toward the wall face, and switching the eddy current flaw detecting sensors for scanning. CONSTITUTION: When a probe 1 is inserted into a flaw inspected pipe, a current applying contact piece 3 is rotated in the peripheral direction of the probe 1 by the drive of a motor. The flaw detection of the heat transfer pipe facing a group of multiple eddy current flaw detecting sensors 2 is conducted by the eddy current generated by a group of multiple eddy current flaw detecting sensors 2 connected to the current applying contact piece 3 in sequence. The eddy current generated on the flaw inspected pipe by each sensor 2 is limited in the partial region of the pipe wall, defects formed in the peripheral direction in the heat transfer pipe can be detected, and flaw detection can be uniformly conducted on the whole periphery of the heat transfer pipe. Flaw detection can be quickly conducted on the flaw inspected pipe via switched scanning in sequence.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe flaw detector for detecting flaws in a metal pipe from the inner surface of the pipe by eddy current flaw detection.

[0002]

2. Description of the Related Art Conventionally, a plurality of long metal pipes (detected pipes),
For example, as a pipe flaw detector for eddy current flaw detection of a heat transfer pipe of a steam generator housed in a reactor containment vessel, FIG. 2, FIG. 3, FIG.
The ones shown in are used.

FIG. 2A is an explanatory view showing a schematic structure of a conventional general pipe flaw detector. As shown in FIG. 2A, the conventional pipe flaw detector includes a probe 21 inserted into a heat transfer pipe, an eddy current flaw detection sensor (self-induction coil) 22a that generates an eddy current and receives a detection signal, 22b and the like. In this type of tube flaw detector, a centering whisker 23 is provided on the probe 21 in order to position the probe 21 at the center (axis center) in the heat transfer tube.

In the conventional pipe flaw detector constructed as described above, as shown in FIG.
1 is inserted into the heat transfer tube 25 in the direction of the arrow, and an eddy current generated from the pair of two eddy current flaw detection sensors 22a, 22b is caused to flow in the circumferential direction of the heat transfer tube 25, and both flaw detection sensors 22a,
22b, and the flaw detection sensors 22a and 22b are received.
It is detected whether or not there is a defect in the heat transfer tube 25 by taking the difference between the output signals output from the respective.
Incidentally, the method of specifying the position of the defect by taking the difference between the output signals output from the two detection sensors in this way is generally called a differential method (differential flaw detection sensor).

FIG. 3A is an explanatory view showing a schematic structure of another conventional pipe flaw detector. The difference from the pipe flaw detector shown in FIG. 2 is that instead of the pair of two eddy current flaw detectors 22a and 22b that generate an eddy current, one eddy current flaw detector 24a (with its coil surface facing the pipe wall surface) A coil smaller than the eddy current flaw detection sensors 22a and 22b shown in FIG.
The point is to detect defects in the heat transfer tube while rotating 1 itself.

In the pipe flaw detector constructed as shown in FIG. 3A, the probe 2 inserted in the heat transfer pipe 25 is used.
While rotating itself, the eddy current flaw detection sensor 24
The a is made to face the entire peripheral surface of the heat transfer tube 25, and it is detected whether or not there is a defect in the heat transfer tube. It should be noted that the eddy current flaw detection sensor 24a provided on the probe 21 scans the inside of the heat transfer tube 25 in a spiral shape as shown in FIG. 3B. Also,
As described above, the method of detecting by using one eddy current flaw detection sensor is generally called an absolute method (absolute flaw detection sensor) as opposed to the differential type.

FIG. 4 is an explanatory view showing a schematic structure of still another conventional pipe flaw detector. The difference from the pipe flaw detector shown in FIGS. 2 and 3 is that a large number (4 to 4) are formed on the circumferential surface of the probe 21 while changing the angle in the circumferential direction of the probe 21.
This is a point in which 16 eddy current flaw detection sensors 24a are arranged.

In the tube flaw detector constructed as shown in FIG. 4, the probe 21 is inserted into the heat transfer tube as it is, so that each eddy current flaw detection sensor is arranged while changing the angle in the circumferential direction of the probe 21. 24a generates an eddy current toward the inner surface of the heat transfer tube facing the respective sensors, and flaw-detects the heat transfer tube. Therefore, the tube flaw detector shown in FIG. 4 has an advantage that it is not necessary to rotate the probe 21 itself in the circumferential direction of the heat transfer tube, as described with reference to FIG.

[0009]

However, the above-mentioned conventional pipe flaw detectors have the following problems. First, in the pipe flaw detector described with reference to FIG. 2, the eddy current flows in the circumferential direction.
As shown in (b), a defect such as a scratch A in the insertion direction of the probe 21 can be detected, but a defect such as a scratch B in the circumferential direction of the pipe to be inspected 25 may not be detected. There was a point.

Further, in the pipe flaw detector described with reference to FIG. 3, it is possible to detect defects in the circumferential direction, but since the probe 21 is rotated, the detection speed is extremely slow and the entire region of the flaw-detected pipe is detected.・ It is not suitable for 100% inspection, and it is used only for partial inspection of the pipe to be inspected.

Further, the tube flaw detector described with reference to FIG. 4 has a problem that detection unevenness occurs.

The present invention has been made in view of the above problems, and a main object of the present invention is to obtain a pipe flaw detection apparatus capable of surely performing flaw detection on the entire circumference of a flaw detection pipe.

Another object of the present invention is to provide a pipe flaw detector which can detect flaws in the circumferential direction of a flaw-detected pipe.

Another object of the present invention is to provide a pipe flaw detector capable of promptly detecting flaws in a flaw-detected pipe.

Still another object of the present invention is to provide a pipe flaw detector capable of uniformly flaw-detecting a flaw-detected pipe.

[0016]

In order to achieve the above object, a pipe flaw detector according to a first aspect of the present invention is a pipe flaw detector for performing eddy current flaw detection from an inner surface of a flaw-detected pipe. It is characterized by comprising a plurality of eddy current flaw detection sensors arranged in an array in the circumferential direction of the probe to be inserted, and a scanning means for scanning the plurality of eddy current flaw detection sensors in the array by switching.

[0017]

The pipe flaw detector according to the first aspect of the present invention comprises a probe, a plurality of eddy current flaw detection sensors (small sensors), and a scanning means. The probe is inserted into the flaw detection tube. Further, the plurality of eddy current flaw detection sensors are arranged in an array in the circumferential direction of the probe with the coil surface facing the wall surface. The scanning means scans the plurality of array-shaped eddy current flaw detection sensors by switching.

That is, a plurality of eddy current flaw detection sensors are arranged in an array in the circumferential direction of the probe, and the plurality of eddy current flaw detection sensors are sequentially switched to be scanned by the scanning means, so that the entire circumference of the pipe to be inspected is eddy current flaw detection. To do.

As a result, it is possible to surely detect the entire circumference of the pipe to be inspected. Therefore, it is possible to detect defects in the circumferential direction of the flaw-detecting pipe, and it is possible to uniformly detect the flaw-detecting pipe. Further, since the plurality of eddy current flaw detection sensors are sequentially switched to scan, the flaw detection target pipe can be promptly detected without causing relative rotational motion with the inner surface of the pipe.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1A is an explanatory view showing the schematic construction of a pipe flaw detector according to an embodiment of the present invention. In the pipe flaw detector according to this embodiment, as shown in FIG. 1A, a plurality of eddy current flaw detector sensors (for example, self-induction type coils) 2 are arranged in an array in the circumferential direction of a probe 1. .

FIG. 1B is a schematic configuration diagram showing the inside of the probe 1. As shown in FIG. 1B, a current is supplied to the plurality of eddy current flaw detection sensor groups 2 inside the probe 1. A current applying probe (scanning means) 3 to be applied is in contact with a current applying terminal 2a of the plurality of eddy current flaw detection sensor groups 2. The current applying probe 3 can be rotated in the circumferential direction of the probe 1 by driving a motor (not shown).

In the pipe flaw detector according to this embodiment constructed as described above, the probe 1 is inserted into the flaw-detected pipe (for example, the heat transfer pipe of the steam generator housed in the reactor containment vessel). Then, the current applying tentacle 3 is rotated in the circumferential direction of the probe 1 by driving a motor (not shown).

As a result, eddy currents generated from the plurality of eddy current flaw detection sensor groups 2 sequentially connected to the current applying contactor 3 detect flaws in the heat transfer tube facing the plurality of eddy current flaw detection sensor groups 2. Be seen.

The eddy current generated in the flaw-detecting pipe by each sensor is limited to a partial region of the pipe wall, so that the flaw in the circumferential direction in the heat-transfer pipe can be detected and the heat-transfer pipe can be detected. It is possible to detect flaws evenly around the entire circumference. Further, since the plurality of eddy current flaw detection sensor groups 2 are sequentially switched and scanned by the current applying probe 3, the flaw detection target tube can be scanned at a higher speed than the conventional device (see FIG. 3) without mechanical relative rotation with respect to the inner surface of the tube. It is also possible to quickly detect flaws.

The eddy current flaw detection sensor group 2 in this embodiment
May use the sensor of either the differential type or the absolute type described in the conventional example.

Further, in the present embodiment, by rotating the current applying probe 3 in the circumferential direction of the probe by the motor, the plurality of eddy current flaw detection sensor groups 2 arranged in an array in the circumferential direction of the probe are sequentially arranged. Although the case of contact-type switching scanning in which an eddy current is generated has been described, it is also within the technical scope of the present invention to operate the plurality of eddy current flaw detection sensors 2 by contactless-type switching scanning by an electronic circuit. It goes without saying that it will be done.

[0027]

As described above, the present invention has an effect that the entire circumference of the pipe to be inspected can be surely inspected.

The present invention also has the effect of being able to detect defects in the circumferential direction of the pipe to be detected.

Further, the present invention has an effect that it is possible to detect a flaw in the flaw-detecting pipe promptly.

Further, the present invention has an effect that it is possible to perform flaw detection on the flaw-detected pipe without unevenness.

[Brief description of drawings]

FIG. 1A is an explanatory diagram showing a schematic configuration of a pipe flaw detector according to an embodiment of the present invention. (B) is a schematic block diagram which shows the inside of a probe.

FIG. 2A is an explanatory diagram showing a schematic configuration of a conventional general pipe flaw detector. (B) is an explanatory view showing the direction of the vortex flow flowing in the flaw detection tube.

FIG. 3A is an explanatory diagram showing a schematic configuration of another conventional tube flaw detector. (B) is an explanatory view showing the direction of the eddy current flaw detection sensor for scanning the inside of the flaw detection tube.

FIG. 4 is an explanatory diagram showing a schematic configuration of still another conventional tube flaw detector.

[Explanation of symbols]

 1: Probe 2: Eddy current flaw detection sensor 3: Current application probe (scanning means)

Claims (1)

[Claims] 1. A pipe flaw detector for eddy current flaw detection from an inner surface of a flaw detection pipe, comprising: a plurality of eddy current flaw detection sensors arranged in an array in a circumferential direction of a probe inserted into the flaw detection pipe; And a scanning unit that scans the eddy current flaw detection sensor by switching.