JPH0344245B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for detecting flaws and/or measuring wall thickness of a tube using ultrasonic waves, and particularly to an apparatus capable of measuring all directions of a tube evenly and simultaneously.

Boiler equipment, especially the tubes of superheaters, reheaters, etc. of high-temperature, high-pressure power generation boilers, have high-temperature, high-pressure steam flowing inside them, and their outer surfaces come into contact with high-temperature combustion gas, so it is difficult to reduce their wall thickness or damage them. During periodic boiler inspections, it is necessary to carefully investigate the boiler to ensure its safety. Moreover, there is a problem in that during regular inspections, inspections of a large number of pipes must be completed in a short period of time. However, these superheater tubes are located in the combustion gas passage,
Dust and clinker are deposited on its outer surface, and it is located near a high place, making it difficult to inspect.In addition, it requires careful inspection, and there are an extremely large number of pipes. Furthermore, in reality, it is almost impossible to carefully inspect these pipes by removing dust from the outer surface of the pipes. However, there is a strong need to develop a means that satisfies these conditions and is capable of highly reliable inspection of damage and wall thickness reduction in a large number of pipes in a short period of time.

For this reason, the inventors have devised the following device to enable inspection from inside the pipe, which is free of dust, etc., and from a safe location such as a vent house on the ceiling of the furnace.

1 and 2 are longitudinal cross-sectional views of a conventional ultrasonic measuring device. First, in Figure 1,
A vertical probe 1 and a reflector 2 that emit ultrasonic waves in the axial direction are disposed inside the probe structure 4, and the ultrasonic beam b emitted from the probe 1 is transmitted to the reflector 2. and changes its direction by almost 90 degrees to the aperture 4a.
The tube then goes to the tube body 5, which is the object to be examined. In this case, in order to perform flaw detection and wall thickness measurement in all directions of the tube (hereinafter referred to as "flaw detection"), the reflector is rotated and the reflection direction of the ultrasonic beam b is sequentially moved in the circumferential direction of the tube. In this case, the probe structure (including the outer box) 4 itself, which is the combination of the probe and the reflector, must be formed integrally, so an opening should be formed around the entire circumference of the structure. I can't. In other words, when performing omnidirectional flaw detection, the connecting portions that do not have openings become interference objects to the propagation of sound waves, making the flaw detection measurement inaccurate. In addition, a motor 3 is also particularly required to rotate the reflector 2. Note that since the probe structure is inserted deep into the tube, it is virtually impossible to rotate this structure itself. Also, a means for displaying and communicating to the operator the direction of orientation of the reflective surface of the reflector is required.

The apparatus shown in FIG. 2 is constructed to solve the above-mentioned problems. That is, in this device, a large number of ultrasonic transducers 6 are arranged on the outer peripheral surface of a damper material 7 that is cylindrical and made of a material that does not interfere with ultrasonic waves, and these ultrasonic transducers are subjected to electronic scanning, etc. It is configured to transmit and receive signals by sequentially switching signals. This eliminates the need to rotate the reflector and eliminates the occurrence of blind spots such as the non-aperture shown in FIG. 1, but on the other hand, the probe structure becomes complicated and the apparatus becomes expensive.

SUMMARY OF THE INVENTION An object of the present invention is to provide an apparatus that can simultaneously measure all directions of a tube as a subject without performing complicated signal switching while keeping the relative positions of a probe and a reflector fixed.

In short, the present invention is an ultrasonic measuring device for detecting the wall thickness and flaws of a specimen having an annular cross section using an ultrasonic beam, in which a probe and a reflector are arranged approximately coaxially, and the transducer of the probe is The reflector is formed into an annular shape, and the reflector has a conical surface with the top thereof located on the probe side and on the axis, and having a curvature such that the ultrasonic beam is focused on the surface of the object. , an ultrasonic measurement characterized in that the set of the probe and the reflector arranged in series is formed so as to be integrally displaced within the object and emit an ultrasonic beam that is incident almost perpendicularly to the object surface. It is a device.

Examples of the present invention will be described below.

In FIG. 3, reference numeral 9 denotes an annular probe (including the vibrator 8), which is arranged so as to be located approximately on the same axis as the tube body 5, which is the object to be examined. 10
is a reflector with a reflecting surface 10a formed in a substantially conical shape, and by inserting the rod-shaped portion 10b at the tip into the hollow part of the annular probe 9, the reflector itself is aligned with the probe and the same axis 9a. The main body of the measuring device is constructed by arranging the measuring device so as to be located on the line, and by integrally constructing the two. Reference numeral 8 denotes an annular vibrator attached to the probe 9 so as to face the reflective surface 10a of the reflector 10. 11 is a rod for inserting a probe attached to the probe 9, and 12 is a connector including a connection line to a power source and a transmission wire. Further, reference numeral 13 is a ball bearing type alignment part attached to the outer periphery of the probe 9 and the outer periphery of the reflector 10, which is screwed together with the probe 9 and the reflector 10, and the screwed state is maintained. By adjusting the distance between the probe 9 and the reflector 10 and the inner wall surface of the tube body 5, the measuring device is centered within the tube body 5, and the device can be easily moved. Further, if necessary, it is preferable that the illustrated ball elastically contact the inner surface of the tube body 5 so as to be able to accommodate some differences in tube diameter.

In the above device, the ultrasonic beam c emitted from the annular transducer 8 is almost perpendicular to the axis of the reflector 10 at the reflecting surface 10a of the opposing reflector 10; It is reflected in the orthogonal plane and goes towards the tube pair 5. The ultrasonic beam c that has reached the tube pair 5 is reflected by the inner and outer surfaces of the tube body 5, and then returns to the transducer 8 and is received in the reverse order of transmission. Note that when testing a subject, a medium (for example, water) 14 is filled into the subject.

FIG. 4 shows a cathode ray tube waveform of an ultrasonic flaw detector when an ultrasonic beam is incident on the tube body 5. S indicates a reflected waveform from the inner surface of the tube, and B indicates a reflected waveform from the outer surface of the tube. In this case, S
The distance t from to B represents the minimum wall thickness in all directions of the tube. Also, the distance t from this cathode ray tube waveform
is configured to be displayed digitally or on a printer using a control box 23 connected to the connector 12.

Next, we will discuss the shape of the reflective surface of the reflector.

In FIG. 5, the reflector 101 is a conical reflecting surface 101.
This shows the radiation state of the ultrasonic beam e in the case of a.In reality, the ultrasonic beam from the annular transducer 8 is not necessarily parallel to the axis 9a, but rather diffuses and is incident on the subject 5. When e ₁ , e ₂ ,
It becomes e ₃ . That is, a multipath phenomenon occurs in which a time difference occurs due to the spread of sound waves. That is, the display of the echo on the cathode ray tube has the shape shown in Figure 5A and has the "spreading of the sound wave" We, and the spread of the ultrasound causes diffusion attenuation of the ultrasound energy, and the echo intensity also decreases. I will do it.

On the other hand, when the cross-sectional curve of the anti-slanted surface 100a displayed in the cross-section including the axis of the reflector 100 is made to have a curvature as shown in FIG.
They become f ₁ , f ₂ , and f ₃ and are focused, eliminating multipath and increasing the echo intensity. This cross-sectional curve is preferably an elliptic curve on which the ultrasound beam is focused geometrically. In that case, “sound wave spread” W _f is the 6th A
As shown in the figure, it becomes narrower than W _e , the echo intensity becomes stronger, and the measurement accuracy improves. If the tube has a thin part, the echo _B1 (indicated by a dotted line) shown in Fig. 6A will be displayed, and _tn is the echo of the tube in the plane of the part being inspected perpendicular to the axis 9a. This indicates the minimum wall thickness t _n . This t _n can be shown on a digital display. In this case, the reflected waves (echoes) from areas with specified (standard) wall thickness are electrically removed, and the echoes from thin wall areas are sent to the control box 24, and the digital display dimensions display the minimum wall thickness within the cross section of the inspection area. It can be made into something.

FIG. 7 shows another embodiment. In contrast to the previous embodiment in which the measuring device main body was placed inside the tube, in this embodiment the measuring device main body is placed surrounding the outer surface of the tube 5. In the figure, reference numeral 19 denotes a probe 18 having a central cavity and arranged surrounding the tube body 5.
It is a ring-shaped vibrator attached to the 15 is a reflector placed around the tube body 5, and the probe 19
Similarly, a central cavity 151 surrounding the axis is provided. Reference numeral 15a denotes a reflecting surface formed on the end surface of the reflector 15, and in order to make the ultrasonic beam oscillated from the transducer 18 enter from the outer surface side of the tube body 5, the reflection surface 15a is formed on the axis of the reflector 15, contrary to the previous embodiment. It is formed into a concave conical surface with an apex at .

An ultrasonic flaw detection device having such a structure is suitable for detecting the thickness and/or defects of a new pipe with few irregularities or scales on the outer surface. That is, by using a magnetic eddy current flaw detector or the like, new pipes continuously delivered from a pipe manufacturing factory or the like are used to inspect the central cavity 151 of the apparatus shown in FIG. 7 according to an embodiment of the present invention at a considerable speed. By passing it through the test, it is possible to perform a more reliable and accurate inspection.

The wall thickness of a pipe is measured using the device according to an embodiment of the present invention, and the relationship between the wall thickness measured by cutting and actually measured is as shown in FIG. 8, and the accuracy is ±0.09 mm. It was highly accurate.

By implementing this invention, it is possible to simultaneously send an ultrasonic beam to the entire circumference of the subject in all directions and receive the reflected waves (echoes), which reduces inspection time and improves inspection accuracy. It is possible to conduct highly efficient inspections that increase

In addition, there is no need for a rotating mechanism for the reflector, an electronic control mechanism, etc., making the device cheaper and simpler, reducing the occurrence of failures and increasing the reliability of the device. This is extremely effective in shortening the testing period and improving reliability.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a rotating reflector type ultrasonic measuring device, FIG. 2 is a sectional view of an electronic scanning type ultrasonic measuring device, and FIG. 3 is a part of an ultrasonic measuring device according to an embodiment of the present invention. A broken side view, Fig. 4 is a cathode ray tube waveform diagram when this device is used, Fig. 5 is a partial cross-sectional schematic diagram of the state of diffusion of an ultrasound beam when the reflecting surface is a conical surface, and Fig. 5A is a schematic diagram of the diffusion state of an ultrasound beam. Figure 6 is a schematic diagram of a cathode ray tube display in the case shown in Figure 6. Figure 6 is a partial cross-sectional diagram showing the focusing of an ultrasonic beam on a reflector with a reflective surface with curvature. A schematic diagram of a cathode ray tube display, Fig. 7 is a vertical cross-sectional view of a device in which a subject can pass through the central cavity of the device, showing another embodiment, and Fig. 8 is a measurement when measuring a test tube. It is a drawing showing a comparison of values and actual measured values. 5... tube body, 8, 18... vibrator, 9, 19...
...Probe, 10, 15...Reflector, 10a, 15
a...Reflecting surface, 10b... Rod-shaped part.

Claims (1)

[Scope of Claims] 1. In an ultrasonic measurement device that detects the wall thickness and flaws of a test object having an annular cross section using an ultrasonic beam, a probe and a reflector are arranged approximately coaxially, and the probe is The shape of the transducer is formed into an annular shape, and the reflector has a conical surface with a top portion located on the probe side and on the axis, and having a curvature such that the ultrasonic beam is focused on the surface of the object. The set of the probe and the reflector arranged in series is formed so as to be integrally displaced within the subject and emit an ultrasonic beam that is incident almost perpendicularly to the surface of the subject. Ultrasonic measuring device. 2. The reflector is formed to have a concave conical surface with its apex located within the reflector and on its axis,
2. The ultrasonic measurement device according to claim 1, wherein the object to be examined is configured to be able to pass through and be displaced within the central cavity of the probe and the reflector. 3. The ultrasonic measuring device according to claim 1 or 2, wherein the object to be examined is a tube, the vibrator is annular, and the reflecting surface of the reflector is a concave conical surface. 4. The ultrasonic measuring device according to any one of claims 1 to 3, further comprising a converter that digitally displays the minimum wall thickness dimension of the measured cross section of the object.