JPH0715456B2 - Ultrasonic testing equipment for pipes - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic flaw detector for a pipe, and more particularly to a probe for transmitting an ultrasonic wave in the axial direction of a pipe to be inspected, A rotating mirror that reflects the ultrasonic waves from the probe to the tube wall of the test tube,
The present invention relates to a water immersion type ultrasonic flaw detector for a pipe, which has a turbine integrally connected to the mirror and rotating the mirror concentrically with the tube axis of the tube to be inspected.

[Prior Art] As a water immersion type ultrasonic flaw detector for flaw detection on the inner surface of a metal tube, an ultrasonic pulse transmitted in the tube axis direction of the tube to be inspected from a probe is rotated by a mirror concentric with the tube axis. There is known a structure in which an echo wave from the tube wall of the test tube is reflected, and then an echo wave from the tube wall is reflected by the mirror and is received by the probe (for example, Japanese Patent Laid-Open No. 2000-242242). 60-205254). In this device, the mirror is provided at an angle of 45 ° with respect to the tube axis, and the ultrasonic waves reflected by the mirror are radiated perpendicularly to the tube wall and reflected on the inner wall surface of the tube. It is configured to receive the incoming echo wave, calculate the distance between the shaft center and the pipe wall from the time from the emission to the reception, and measure the wall thickness reduction due to corrosion of the pipe inner wall surface. It was

[Problems to be Solved by the Invention] The conventional device for applying the above-mentioned ultrasonic waves to the pipe wall perpendicularly has a problem that cracks and the like existing inside the pipe wall due to stress corrosion cannot be detected. .

The present invention has solved such problems, and an object of the present invention is to provide an ultrasonic flaw detector for a pipe for efficiently detecting cracks and the like existing inside the pipe wall in the entire circumferential direction. is there.

[Means for Solving Problems] The present invention as means for solving the above problems includes a probe for transmitting ultrasonic waves in the tube axis direction of a tube to be inspected, and a probe from the probe. A rotary mirror that reflects ultrasonic waves to the tube wall of the test tube, and a turbine that is integrally coupled to the mirror and that rotates the mirror concentrically with the tube axis of the test tube are provided. In a water immersion type ultrasonic flaw detector for moving a flaw along a tube axis, ultrasonic waves from the rotating mirror are reflected on the tube wall surface in a direction away from the probe,
The angle of the reflecting surface of the rotating mirror with respect to the axis is inclined at 33 to 37 ° so that the incident angle of ultrasonic waves on the tube wall of the tube to be inspected is 16 to 24 °. The purpose of the present invention is to detect flaws inside the wall. [Operation] In the ultrasonic flaw detector of the present invention, the rotary mirror is set so that the incident angle of the ultrasonic waves on the tube wall of the test tube is 16 to 24 °. Since it is provided, the pulse wave of the ultrasonic wave generated from the probe is reflected by the rotating mirror and is applied to the tube wall at an incident angle of 16 to 24 °. This irradiation ultrasonic wave partially enters the inside of the tube wall, is reflected by scratches such as cracks inside the tube wall, becomes an echo wave, and enters the probe through a route opposite to the approach,
To be measured.

This measurement can be performed in the entire circumferential direction of the tube by rotating the rotating mirror, and the longitudinal direction can also be measured by moving this ultrasonic device along the tube axis. It is possible to efficiently find scratches such as cracks existing inside the pipe wall.

[Embodiment] An embodiment of the present invention applied to a heat transfer tube of a heat exchanger will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes an ultrasonic flaw detector, which is inserted into a heat transfer tube 3 of a tube plate 2 of a heat exchanger, and a centering device 4 made of a spring member allows the flaw detection apparatus 1 and the heat transfer tube 3 to have axes. Set to match. The centering device 4
Is a removable ring and can be replaced with a ring having an outer diameter adapted to the inner diameter of the heat transfer tube.

The ultrasonic flaw detector 1 includes a probe 6 fixed in a housing 5 for transmitting and receiving ultrasonic waves, a rotating mirror 7 for reflecting the ultrasonic waves, a turbine 8 for rotating the mirror 7, and the like.

The rotating mirror 7 and the turbine 8 are integrally coupled, and are fixed to the housing 5 via a bearing bearing 9 between them. Most parts of the turbine 8 are opened between the blade mounting side and the bearing 9 except for the supporting member so that water can pass through.

The ultrasonic reflection surface of the rotating mirror 7 is attached with an inclination with respect to the axis of the tube 2 so that the ultrasonic pulse transmitted from the probe 6 is reflected in the tube wall direction. There is. The ultrasonic reflection surface of the rotary mirror 7 is inclined so that the incident angle α of the ultrasonic wave on the tube wall of the heat transfer tube 3 is 16 to 24 °. If this incident angle α is less than 16 °, the interval between the echo wave from the surface of the tube wall and the echo wave from the scratched surface in the tube wall becomes too small, which makes analysis difficult. On the other hand, when the angle is 24 ° or more, the ultrasonic pulse is totally reflected on the surface of the tube wall, does not enter the inside of the tube wall, and flaws inside the tube wall cannot be detected. Particularly preferably, the incident angle α is about 18
It is ゜. As the method of setting the incident angle α to 16 to 24 °, the most convenient and preferable method is to set the inclination angle of the ultrasonic reflection surface of the rotating mirror 7 to 33 to 37 ° with respect to the axis of the heat transfer tube 3. Also, by setting a specific angle of 45 ° or less, the echo wave reflected on the inner and outer wall surfaces of the pipe is
Since it travels away from the probe, it is not detected by the probe. Since the echo wave from other than the defect is a disturbance, not picking up this disturbance with the probe means that the echo wave from the defect inside the wall is selectively picked up. To realize.

In the ultrasonic flaw detector 1 configured as described above, water is supplied into the heat transfer tube 3 and the housing 5 as an ultrasonic medium, and is constantly filled with water flowing.
Here, the ultrasonic pulse is transmitted from the probe 6 in the axial direction of the tube, is reflected in the tube wall direction by the rotating mirror 7, and is applied to the tube wall at an incident angle of 16 to 24 °. . Here, part of the ultrasonic pulse is reflected by the surface of the tube wall, most of it is scattered, part of it becomes an echo wave, reaches the rotating mirror 7, is reflected again by this mirror 7, and is received by the probe 6. To be done. On the other hand, a part of the ultrasonic pulse applied to the tube wall enters the inside of the tube wall and is reflected by a scratch 10 such as a crack to be an echo wave.
Is reached, and is reflected again by the mirror 7 and received by the probe 6. If there are no cracks 10 such as cracks, the heat transfer tube 3
Scattered on the outer wall of the probe, it hardly returns to the probe 6 and is not received.

On the other hand, the water supplied into the housing 5 rotates the turbine 8 and passes through the opening between the blade mounting side of the turbine 8 and the bearing 9 to rotate the mirror 7 in the direction along the axis.
Flows toward. The rotating mirror 7 is rotated by the rotation of the turbine 8, and the number of rotations is adjusted by the amount of water supplied into the housing 5. This speed is usually 10
It is sufficient to select in the range of 0 to 1000 rpm. This rotation of the rotating mirror 7 enables measurement of the heat transfer tube 3 in the entire circumferential direction.

Further, longitudinal measurement can be performed by moving the ultrasonic flaw detector 1 back and forth along the axis of the heat transfer tube 3, and by rotating the mirror and moving it back and forth, the entire area of the heat transfer tube can be measured. Done.

Fig. 2 shows the state of this measurement as a waveform on a CRT. That is, when the horizontal axis represents time and the vertical axis represents the intensity of the echo wave pulse, the weak surface echo wave A first reflected on the surface of the inner wall of the tube appears, and then reflected by a scratch in the wall of the tube. The echo wave B having a strong intensity appears. Therefore, it is possible to find the presence and position of stress corrosion cracking, etc. of the heat transfer tube 3 by measuring the detection of the inclination angle and the echo waves B position and the rotating mirror 7 of the ultrasonic flaw detector 1.

[Advantages of the Invention] In the ultrasonic flaw detector for a pipe, the present invention uses a rotating mirror with respect to the axis of the rotary mirror so that the incident angle of the ultrasonic wave on the pipe wall of the pipe to be inspected is 16 to 24 °. Since it was installed at an angle of 33 to 37 °, it does not detect echo waves from the inner and outer wall surfaces of the pipe, which is a disturbance for detection of echo waves from defects, and cracks existing inside the pipe wall in the entire circumferential direction. It has a special effect that only scratches such as can be measured with high accuracy and efficiency.

[Brief description of drawings]

FIG. 1 shows one embodiment of the ultrasonic flaw detector of the present invention. In FIG. 1, 1 is an ultrasonic flaw detector, 3 is a heat transfer tube, 6 is a probe, and 7 is a rotating mirror. FIG. 2 shows CR when measured by the ultrasonic flaw detector of the present invention.
It is an example of the waveform on the T screen. In FIG. 2, A shows the waveforms of the echo wave reflected by the surface of the inner wall of the tube and the echo wave reflected by the scratch in the wall of the tube.

Claims (1)

[Claims] 1. A probe for transmitting ultrasonic waves in the tube axis direction of a tube to be inspected, a rotating mirror for reflecting ultrasonic waves from the probe to the tube wall of the tube to be inspected, and a mirror integrated with the mirror. Ultrasonically detecting apparatus for a water-immersed tube that has a turbine that is coupled to the tube to rotate the mirror concentrically with the tube axis of the tube to be inspected and moves along the tube axis of the tube to be inspected. In, so that the ultrasonic wave from the rotating mirror is reflected on the tube wall surface in the direction away from the probe, and the incident angle of the ultrasonic wave to the tube wall of the test tube is 16 to 24 °, An ultrasonic flaw detector for a pipe for detecting a defect inside a pipe wall, wherein the angle of the reflecting surface of the rotating mirror with respect to the axis is inclined at 33 to 37 °.