JP5957425B2 - Apparatus and method for measuring the thickness of internal deposits - Google Patents

Description

  The present invention relates to an apparatus and a method for measuring the thickness of an internal deposit such as a scale adhered to the inside (inner surface or back surface) of a tubular or plate-like object to be inspected.

  When the thickness of the steam oxidation scale adhering in the heat transfer tube of the boiler increases, the thermal conductivity may decrease, and the heat transfer tube may be overheated and become a cause of damage. The steam oxidation scale is usually iron oxide.

  Scale also adheres to pipes other than the heat transfer pipes of the boiler, such as various pipes used in power plants and chemical plants. Such scales are, for example, scales, polymers, chemical compounds, and the like.

  In the above-described boiler, power plant, chemical plant, and the like, various scales adhering to the pipe adversely affect the respective devices, and therefore it is necessary to measure them with high accuracy periodically.

  For this purpose, the thickness measurement of the pipe scale using ultrasonic waves has been conventionally performed. However, when the scale thickness is small, ultrasonic reflected echoes on the boundary surface and the bottom surface are superimposed, which makes it difficult to read each peak.

  Therefore, as a measurement means when the scale thickness is thin, a means for searching the feature of the superimposed echo from the back data and measuring the scale thickness using this feature, or a transmission step waveform instead of a pulse wave is used. Means have been proposed for improving the resolution by using (for example, Patent Documents 1 to 4).

Japanese Patent Laid-Open No. 9-304041 JP 2001-183126 A JP 2002-365032 A JP 2008-14868 A

  However, the conventional measuring means when the scale thickness is thin has a problem that a special device such as an analysis computer or a waveform generator is required.

  The present invention has been developed to solve the above-described problems. That is, the object of the present invention is to measure the thickness of the internal deposit from the outer surface with high accuracy even when the thickness of the internal deposit (for example, the scale) is thin and the reflected echoes of the ultrasonic waves on the boundary surface and the bottom surface overlap. An object of the present invention is to provide an apparatus and a method for measuring the thickness of an internal deposit.

According to the present invention, there is provided a thickness measuring device for an internal deposit that measures the thickness of the internal deposit attached to the inner surface or the back surface of the object to be inspected with ultrasonic waves,
The reflected wave of the ultrasonic wave consists of a boundary surface echo reflected at the boundary surface between the inner surface or back surface of the object to be inspected and the internal deposit, and a bottom surface echo reflected from the inner surface or back surface of the internal deposit,
The boundary surface echo and the bottom surface echo each have a front extreme point that precedes the maximum peak and a rear extreme point that is delayed from the maximum peak, respectively.
A probe that receives ultrasonic waves from the outer surface of the object to be inspected and receives the reflected waves; and
An arithmetic unit that calculates the thickness of the internal deposit from the reflected wave, and
(A) An ultrasonic wave is incident from the outer surface of a reference specimen corresponding to an object to be inspected to which no internal deposit is attached, and the reflected wave is received as a reference waveform;
(B) The front time difference Δt1 between the maximum peak and the front extreme point in the reference waveform and the rear time difference Δt2 between the maximum peak and the rear extreme point are stored in advance.
(C) An ultrasonic wave is incident from the outer surface of the object to be inspected, and the reflected wave is received as an inspection waveform;
(D) The conversion time t3 of the maximum peak of the boundary surface echo is converted from the detection time point of the front extreme point of the boundary surface echo included in the inspection waveform and the front time difference Δt1, and the bottom surface echo included in the inspection waveform is converted. The conversion time T3 of the maximum peak of the bottom echo is converted from the detection time of the rear extreme point and the rear time difference Δt2,
(E) A thickness measuring device for an internal deposit is provided, wherein the thickness of the internal deposit adhering to the inner surface or the back surface of the object to be inspected is calculated from the converted time difference Δt between the converted time points t3 and T3. Is done.

The inspection object is a power plant or chemical plant piping or plate inspection object,
The internal deposit is an oxide scale including a steam oxidation scale, a chemical compound, or a resin and rubber, or other chemical compounds.

  The arithmetic device includes an ultrasonic transmission / reception unit, a control unit, and a display unit.

Furthermore, an encoder for detecting positional information of the probe on the outer surface of the inspection object,
The arithmetic unit preferably displays an image image obtained by color-converting the amplitude information of the reflected wave received by the probe together with the position information.

Further, according to the present invention, there is provided a method for measuring the thickness of internal deposits by ultrasonically measuring the thickness of the internal deposits adhered to the inner surface or the back surface of the test object,
The reflected wave of the ultrasonic wave consists of a boundary surface echo reflected at the boundary surface between the inner surface or back surface of the object to be inspected and the internal deposit, and a bottom surface echo reflected from the inner surface or back surface of the internal deposit,
The boundary surface echo and the bottom surface echo each have a front extreme point that precedes the maximum peak and a rear extreme point that is delayed from the maximum peak, respectively.
(A) An ultrasonic wave is incident from the outer surface of a reference specimen corresponding to an object to be inspected to which no internal deposit is attached, and the reflected wave is received as a reference waveform;
(B) The front time difference Δt1 between the maximum peak and the front extreme point in the reference waveform and the rear time difference Δt2 between the maximum peak and the rear extreme point are stored in advance.
(C) An ultrasonic wave is incident from the outer surface of the object to be inspected, and the reflected wave is received as an inspection waveform;
(D) The conversion time t3 of the maximum peak of the boundary surface echo is converted from the detection time point of the front extreme point of the boundary surface echo included in the inspection waveform and the front time difference Δt1, and the bottom surface echo included in the inspection waveform is converted. The conversion time T3 of the maximum peak of the bottom echo is converted from the detection time of the rear extreme point and the rear time difference Δt2,
(E) A thickness measurement method for an internal deposit is provided, wherein the thickness of the internal deposit adhered to the inner surface or the back surface of the object to be inspected is calculated from the converted time difference Δt between the converted time points t3 and T3. Is done.

In (A), a reference waveform is stored,
In (D), a reference waveform is superimposed on the inspection waveform and displayed.

  The front extreme point and the rear extreme point are peaks or bottoms of reflected waves.

Each of the boundary surface echo and the bottom surface echo has three peaks of a front peak, a maximum peak, and a rear peak in order,
The front extreme point is the front peak,
The rear extreme point is preferably the rear peak.

Detecting position information of the probe on the outer surface of the object to be inspected;
It is preferable that an image image obtained by color-converting the amplitude information of the reflected wave received by the probe is displayed together with the position information.

  According to the apparatus and method of the present invention, the front extreme point (peak) of the boundary echo is obtained even when the internal deposit (for example, the scale) is thin and the reflected echoes of the ultrasonic waves at the boundary and the bottom overlap. (Or bottom) always precedes the bottom echo and can be easily detected without being superimposed on the bottom echo. Therefore, the conversion time t3 of the maximum peak of the boundary surface echo can be converted from the front time difference Δt1 between the maximum peak in the reference waveform and the front extreme point.

  Similarly, even if the internal deposit (for example, the scale) is thin and the reflected echoes of the ultrasonic waves at the boundary surface and the bottom surface overlap, the rear extreme point (peak or bottom) of the bottom surface echo is preceded. Since it always lags behind the boundary surface echo, it can be easily detected without being superimposed on the boundary surface echo. Therefore, the conversion time T3 of the maximum peak of the bottom echo can be converted from the rear time difference Δt2 between the maximum peak and the rear extreme point in the reference waveform.

  The front side time difference Δt1 and the rear side time difference Δt2 are the same ultrasonic waves reflected in the same object when the object to be inspected and the probe are the same, and therefore have the same value for the boundary surface echo and the bottom surface echo. . Therefore, the conversion points t3 and T3 of the maximum peak converted as described above are substantially the same as the maximum peak points when the reflected echo is not superimposed, and the thickness of the internal deposit is determined from the time difference Δt. Can be measured with high accuracy.

It is a figure which shows the conventional measurement means of scale thickness. It is a whole block diagram of the thickness measuring apparatus of the internal deposit by this invention. It is a whole flowchart of the thickness measurement method of the internal deposit by this invention. It is a figure which shows an example of a reference | standard waveform. It is a figure which shows an example of a test | inspection waveform. It is a figure which shows the example which overlapped and displayed the reference waveform on the test | inspection waveform. It is a figure which shows the reference waveform by a different probe. It is the figure which put together the result of FIG. It is a figure which shows the reference | standard waveform in case the material of a test body differs. It is the figure which put together the result of FIG. It is a figure which shows a reference | standard waveform in case the thickness of a test body differs. It is the figure which put together the result of FIG. It is a B image image (A) and a contrast image (B) in which the B image image and the inspection waveform are written together in the case where the object to be inspected is a reference test body to which no internal deposit is attached. It is a figure similar to FIG. 13 when the thickness of an internal deposit is thin. It is a figure similar to FIG. 13 when the thickness of an internal deposit is thick.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In each figure, common portions are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a diagram showing a conventional means for measuring scale thickness. In this figure, (A) is the case where the scale thickness of the boiler tube is thick, and (B) is the case where the scale thickness is thin, and each is a reflected waveform (reflection echo) of an ultrasonic wave. In each figure, the horizontal axis represents time t, and the vertical axis represents the waveform intensity F.

As shown in FIG. 1 (A), the reflected echo of the ultrasonic wave includes a boundary surface echo I reflected from the boundary surface between the boiler tube and the inner surface thereof, and a bottom surface echo B reflected from the inner surface of the scale. It is.
When the scale thickness is thick, the boundary echo I and the bottom echo B are temporally separated as shown in FIG. 1A, and the time difference Δt between the maximum peaks can be easily read. Accordingly, the scale thickness d is obtained by calculating the time difference Δt between the maximum peaks of the boundary surface echo I and the bottom surface echo B, multiplying this by the sound velocity V, and dividing by 2 (d = Δt × V / 2). be able to.

  As shown in FIG. 1B, when the scale thickness is small, the boundary surface echo I and the bottom surface echo B partially overlap each other, so that the maximum peaks cannot be separated in time, and the maximum peaks are not separated. It becomes difficult or impossible to read the time difference Δt. Therefore, even if reading is possible, there is a problem that the accuracy is greatly reduced.

FIG. 2 is an overall configuration diagram of the thickness measuring device 10 for the internal deposit 2 according to the present invention.
In this figure, a thickness measuring apparatus 10 of the present invention is an apparatus for measuring the thickness d of an internal deposit 2 attached to the inside (inner surface or back surface) of an object 1 with an ultrasonic wave 3.

In this example, the inspection object 1 is a heat transfer tube of a boiler, but may be a piping of a power plant or a chemical plant. Moreover, the to-be-inspected object 1 is not limited to a pipe | tube, As long as it has an inner surface, a container (for example, pressure vessel) or a plate-shaped inspection object may be sufficient.
The internal deposit 2 is a steam oxidation scale in this example, but may be an oxide scale, a chemical compound, or resin and rubber, or other chemical compounds. Further, the internal deposit 2 is not limited to these examples, and may be any substance as long as the sound velocity V propagating through the inside is known or measurable.

  In FIG. 2, the thickness measuring device 10 of the present invention includes a probe 12 and a calculation device 14.

  The probe 12 is attached to the outer surface of the inspection object 1 (for example, a tube) via the contact medium 11, and the ultrasonic wave 3 is incident on the inner side of the inspection object 1 and the reflected wave 4 is received.

The computing device 14 is, for example, a computer (PC), and calculates the thickness d of the internal deposit 2 (for example, scale) from the reflected wave 4.
In this example, the arithmetic device 14 includes an ultrasonic transmission / reception unit 15, a control unit 16, and a display unit 17. The ultrasonic transmission / reception unit 15 transmits the ultrasonic wave 3 to the probe 12 and receives the reflected wave 4 from the probe 12. The control unit 16 calculates the thickness d of the internal deposit 2 (for example, scale) from the reflected wave 4. The display unit 17 is a display device (CRT or the like).

  FIG. 3 is an overall flowchart of the method for measuring the thickness of the internal deposit 2 according to the present invention. As shown in this figure, the method of the present invention comprises steps (processes) S1 to S5.

In step S1, an ultrasonic wave 3 is incident on the reference specimen 1A from the outer surface of the reference specimen 1A corresponding to the inspection object 1 to which the internal deposit 2 is not attached, and the reflected wave 4 is inputted to the reference waveform 5. As received.
In step S1, the reference waveform 5 is preferably stored in a storage device (not shown) of the arithmetic device 14.

  It is preferable that the reference test body 1A corresponding to the test object 1 to which the internal deposit 2 is not adhered is substantially the same except that the test object 1 and the internal deposit 2 are not adhered. However, the present invention is not limited to this, and as long as the shape of the reference waveform 5 is substantially the same, a reference specimen 1A having a different shape, material, etc. may be used.

FIG. 4 is a diagram illustrating an example of the reference waveform 5. In this figure, the reference waveform 5 has a front extreme point that precedes the maximum peak P3 and a rear extreme point that lags behind the maximum peak P3. The front extreme point and the rear extreme point are peaks or bottoms of the reflected wave 4.
In this example, the front extreme points are the front peak P1 and the front bottom P2, and the rear extreme points are the rear bottom P4 and the rear peak P5.
The reference waveform 5 is not limited to this example, and may have at least one front extreme point and rear extreme point before and after (in time) the maximum peak P3.

Hereinafter, in the example of FIG. 4, the case where the front extreme point is the front peak P1 and the rear extreme point is the rear peak P5 will be described.
The selection of the front extreme value point and the rear extreme value point is arbitrary, and the front extreme value point may be the front bottom P2, and the rear extreme value point may be the rear bottom P4.

In step S2, in the example of FIG. 4, the front time difference Δt1 between the maximum peak P3 and the front extreme point (front peak P1) in the reference waveform 5, and the maximum peak P3 and the rear extreme point (rear peak P5). The rear time difference Δt2 is stored in advance.
In the example of FIG. 4, the target of the front time difference Δt1 and the rear time difference Δt2 is not limited to the front peak P1 and the rear peak P5, and the front bottom P2 or the rear bottom P4 may be used. Further, when the reference waveform 5 includes other extreme points (peak or bottom), other extreme points may be used.

  In step S <b> 3, the ultrasonic wave 3 is incident on the inspection object 1 from the outer surface of the inspection object 1 with the internal attachment 2 as the inspection object, and the reflected wave 4 is received as the inspection waveform 6.

Hereinafter, the maximum peaks of the boundary surface echo I and the bottom surface echo B corresponding to the maximum peak P3 of the reference waveform 5 are defined as p3 (lower case) and q3 (lower case).
Similarly, the front extreme points (front peak and bottom) of the boundary surface echo I corresponding to the front extreme points (front peak P1 and front bottom P2) of the reference waveform 5 are p1, p2 (lower case), and the reference. The rear extreme points of the bottom echo B corresponding to the rear extreme points (rear bottom P4 and rear peak P5) of the waveform 5 are defined as q4 and q5 (lower case letters).

In step S4, the conversion time point t3 of the maximum peak p3 of the boundary surface echo I is converted from the detection time point t1 of the front extreme point (front peak p1) of the boundary surface echo I included in the inspection waveform 6 and the front time difference Δt1. This conversion formula can be expressed by t3 = t1 + Δt1 (1).
In parallel, the conversion time T3 of the maximum peak q3 of the bottom echo B is converted from the detection time T5 of the back extreme point (back peak q5) included in the inspection waveform 6 and the rear time difference Δt2. . This conversion formula can be expressed by T3 = t5−Δt2 (2).

  In step S <b> 4, the reference waveform 5 is preferably superimposed on the inspection waveform 6 and displayed on the image of the display unit 17. By displaying in this way, the detection point t1 of the front extreme point (front peak p1) and the detection point T5 of the rear extreme point (rear peak q5) can be easily discriminated on the image, and converted. Conversion of the time points t3 and T3 can be performed accurately.

  In step S5, the thickness d of the internal deposit 2 adhered to the inner surface of the device under test 1 is calculated from the time difference Δt between the conversion times t3 and T3. This calculation formula can be expressed by d = Δt × V / 2 (3).

FIG. 5 is a diagram illustrating an example of the inspection waveform 6.
In this example, the front peak p1 of the boundary surface echo I and the back peak q5 of the bottom surface echo B can be identified. However, since the boundary echo I and the bottom echo B are superimposed on other extreme points (peaks or bottoms), the waveforms are synthesized and are difficult to identify.
According to the present invention, even in such a case, the thickness d of the internal deposit 2 adhered to the inner surface of the inspection object 1 can be calculated from the time difference Δt between the conversion times t3 and T3.

  FIG. 6 is a diagram illustrating an example in which the reference waveform 5 is superimposed on the inspection waveform 6 on the image of the display unit 17. In this figure, the solid line is the inspection waveform 6 in the object 1 to be inspected, and the broken line is the reference waveform 5 in the reference specimen 1A.

When the thickness of the internal deposit 2 is (A) is thick (about 700 μm), (B) is thin (about 150 μm).
6A and 6B, the front time difference Δt1 (= 0.086 μs) and the rear time difference Δt2 (= 0.109 μs) are the same.

In FIG. 6A, the detection time t1 (= 3.806 μs) of the front peak p1 and the detection time T5 (= 4.252 μs) of the back peak q5 can be easily discriminated on the image.
Therefore, from the above equation (1), t3 = t1 + Δt1 = 3.806 μs + 0.086 μs = 3.892 μs, and from the above equation (2), T3 = t5−Δt2 = 4.252 μs−0.109 μs = 4.143 μs. From the above equation (3), the thickness d of the internal deposit 2 is calculated as d = Δt × V / 2 = (4.143 μs−3.892 μs) × (5920 m / s) / 2 = 743 μs. can do.

Similarly, in FIG. 6B, the detection time t1 of the front peak p1 (= 1.793 μs) and the detection time T5 of the back peak q5 (= 2.036 μs) can be easily discriminated on the image. .
Therefore, from the above equation (1), t3 = t1 + Δt1 = 1.793 μs + 0.086 μs = 1.879 μs, and from the above equation (2), T3 = t5−Δt2 = 2.036 μs−0.109 μs = 1.927 μs. From the above formula (3), the thickness d of the internal deposit 2 is calculated as d = Δt × V / 2 = (1.927 μs−1.879 μs) × (5920 m / s) / 2 = 142 μs. can do.

(Difference in the reference waveform 5 due to the difference in the probe 12)
FIG. 7 is a diagram showing the reference waveform 5 by different probes 12. In this figure, (A) has a frequency of 10 MHz, (B) has a frequency of 15 MHz, and (C) has a frequency of 20 MHz, and the lots of the probes 12 are different in the left and right waveforms of each stage. The numbers in the figure indicate the propagation time difference (μsec) between the peaks. The specimen used was JIS Z 2345 STB-N1, and the bottom echo B was used as the reference waveform 5.

FIG. 8 is a table summarizing the results of FIG. In this figure, ● represents the time difference (P3-P1) between the maximum peak P3 and the previous peak P1, and ■ represents the time difference (P4-P3) between the rear bottom P4 and the maximum peak P3.
7 and 8, it can be seen that even at the same frequency, the propagation time difference for each peak differs if the lot of the probe 12 is different. Therefore, it was confirmed that it is desirable to check the reference waveform 5 for each probe 12 to be used when measuring the thickness of the deposit.

(Difference in reference waveform 5 depending on specimen material)
FIG. 9 is a diagram showing the reference waveform 5 when the material of the test body is different. The specimens used were (A) SM490, (B) 9Cr steel, (C) 12Cr steel, (D) SUS304, (E) aluminum, and (F) quartz glass. The thickness of the specimen was 30 mm, and the probe 12 having a frequency of 10 MHz was used. In addition, the number in a figure has shown the propagation time difference (microsecond) between each peak.

FIG. 10 summarizes the results of FIG.
9 and 10, it can be seen that the reference waveform 5 has almost the same shape, but the propagation time differs depending on the material. For this reason, it is desirable to prepare the reference test material 1A made of the same material as that of the object to be inspected 1 and to observe the reference waveform 5 using the reference test material 1A when measuring the thickness of the deposit.

(Difference in reference waveform 5 due to wall thickness)
FIG. 11 is a diagram showing the reference waveform 5 when the thicknesses of the specimens are different. The specimen used was SM490, and the thicknesses were (A) 10 mm, (B) 15 mm, (C) 30 mm, and (D) 45 mm. The frequency is 10 MHz.

FIG. 12 summarizes the results of FIG.
From FIG. 11 and FIG. 12, it was recognized that the propagation time difference tends to be slightly different depending on the wall thickness. Therefore, it is desirable to observe the reference waveform 5 using the reference specimen 1A having the same thickness as the object to be inspected.

From the results of Examples 2 to 4 described above, it is desirable to perform the following as preparation when measuring the thickness of the deposit.
A reference test body 1A having the same material and the same thickness as the object 1 is prepared.
Using the reference specimen 1A, the reference waveform 5 of the probe 12 to be used is observed, and the peak interval is checked.

Next, an apparatus and method for determining the presence or absence of the internal deposit 2 using the thickness measuring apparatus 10 will be described.
The thickness measuring apparatus 10 further includes an encoder that detects position information of the probe 12 on the outer surface of the inspection object 1.
Further, the arithmetic unit 14 displays on the display unit 17 an image image obtained by color-converting the amplitude information of the reflected wave 4 received by the probe 12 together with the position information. Hereinafter, the image image is referred to as a “B image image”.

FIG. 13 shows a B image image (A) and a contrast image (B) in which the B image image and the inspection waveform 6 are written together when the object to be inspected 1 is the reference specimen 1A to which the internal deposit 2 does not adhere. It is.
The B image is color-converted from blue (B) to red (R) depending on the amplitude. In this figure, blue (B) is “1” and red (R) is “9”, and the magnitude of the amplitude is indicated by a small number from 1 to 9.

  The probe 12 is scanned using an encoder with respect to the inspection object 1 (that is, the reference test object 1A) to which the internal attachment 2 is not attached, and positional information of the probe 12 on the outer surface of the inspection object 1 When the amplitude information of the reflected wave 4 received by the probe 12 is acquired and the color-converted image is acquired, a B image image as shown in FIG. 13A is obtained. When the B image and the reflected wave 4 (that is, the reference waveform 5) are described in parallel, the result is as shown in FIG. It can be confirmed that the extreme points and the bottom of P1 to P5 are displayed in six lines.

  FIG. 14 shows a case where the thickness of the internal deposit 2 is thin (338 μm), and FIG. 15 shows a case where the thickness of the internal deposit 2 is large (674 μm). (A) is a B image image, and (B) is a contrast image in which the B image image and the reflected wave 4 are written together. The notation in the figure is the same as in FIG.

  In FIG. 14, the boundary surface echo I and the bottom surface echo B are superimposed, and it can be confirmed that the number of extreme points, which is 6 in the B image image of FIG. 13B, is increased and complicated. Further, in FIG. 15, although the boundary surface echo I and the bottom surface echo B are separated, the line of the extreme point of the B image image increases, and it can be confirmed that it is more complicated than FIG. 2.

  As shown in FIG. 13B, FIG. 14B, and FIG. 15B, the presence or absence of the internal deposit 2 is clear when the reflected wave 4 is also checked for the presence or absence of the internal deposit 2. However, even in the case of only the respective B image images (FIGS. 13A, 14A, and 15A), the determination of the presence or absence of the internal deposit 2 can be made due to the increase of the extreme point line. Easily possible.

That is, by detecting the position information of the probe 12 on the outer surface of the inspected object 1 and displaying the B image image obtained by color-converting the amplitude information of the reflected wave 4 received by the probe 12 together with the position information, For example, in the case where the thickness measurement of the internal deposit 2 of the object 1 to be inspected 1 in which the portion where the internal deposit 2 is not adhered and the portion where the deposit is adhered is continuously measured, a B image of the measurement location in advance. If an image is acquired and the portion where the internal deposit 2 is attached is narrowed down from the B image image, efficient measurement is possible.
In measuring the thickness of the internal deposit 2, it is necessary to detect the extreme points on the front side or the rear side of the boundary surface echo I and the bottom surface echo B, and therefore it is essential to grasp the reflected wave 4. However, the B image is effective in determining the presence or absence of the internal deposit 2.

  According to the above-described apparatus and method of the present invention, even when the thickness d of the internal deposit 2 (for example, the scale) is thin and the reflected echoes of the ultrasonic waves 3 on the boundary surface and the bottom surface overlap, the front side of the boundary surface echo I Since the extreme point (peak or bottom) always precedes the bottom echo B, it can be easily detected without being superimposed on the bottom echo B. Therefore, the conversion time t3 of the maximum peak p3 of the interface echo I can be converted from the front time difference Δt1 between the maximum peak P5 and the front extreme point in the reference waveform 5.

  Similarly, the rear extreme point (peak or bottom) of the bottom echo B even when the internal deposit 2 (for example, the scale) is thin and the reflected echoes of the ultrasonic waves 3 on the boundary surface and the bottom surface overlap. Can always be detected without being superposed on the boundary surface echo I. Therefore, the conversion time T3 of the maximum peak q3 of the bottom echo B can be converted from the rear time difference Δt2 between the maximum peak P5 and the rear extreme point in the reference waveform 5.

  Since the front side time difference Δt1 and the rear side time difference Δt2 are the reflected waves 4 of the same ultrasonic wave 3 in the same object when the inspection object 1 and the probe 12 are the same, the boundary surface echo I and the bottom surface echo B At the same value. Therefore, the conversion points t3 and T3 of the maximum peaks p3 and q3 converted as described above are substantially the same as the maximum peak points when the reflected echo is not superimposed, and from this time difference Δt, the internal deposit 2 The thickness d can be measured from the outer surface with high accuracy.

  Therefore, according to the present invention, a scale having a scale thickness d of 100 μm or less can be measured with high accuracy. If the waveform characteristics and peak interval of the probe 12 are examined, piping of various materials can be measured. Furthermore, it can be applied not only to the scale thickness d but also to film thickness measurement and inner lining thickness measurement.

  In addition, this invention is not limited to embodiment mentioned above, Of course, it can change variously in the range which does not deviate from the summary of this invention.

I Interface echo,
B Bottom echo,
P1, p1 front peak,
P2 Front bottom,
P3, p3, q3 maximum peak,
P4 rear bottom,
P5, p5, q5 after peak,
T3 Time point of conversion of maximum peak of bottom echo t3 Time point of conversion of maximum peak of interface echo Δt Time difference between maximum peaks,
Δt1 front time difference,
Δt2 rear time difference,
d Thickness of internal deposit (scale thickness),
V speed of sound,
1 Inspected object (heat transfer tube, piping),
1A reference specimen,
2 Internal deposits (scale),
3 Ultrasound,
4 Reflected wave,
5 Reference waveform,
6 Inspection waveform,
10 Thickness measuring device,
11 contact medium,
12 Probe,
14 arithmetic unit,
15 Ultrasonic transceiver
16 control unit,
17 Display

Claims (9)

A thickness measuring device for internal deposits, which measures the thickness of the internal deposits adhered to the inner surface or back surface of the object to be inspected with ultrasonic waves,
The reflected wave of the ultrasonic wave consists of a boundary surface echo reflected at the boundary surface between the inner surface or back surface of the object to be inspected and the internal deposit, and a bottom surface echo reflected from the inner surface or back surface of the internal deposit,
The boundary surface echo and the bottom surface echo each have a front extreme point that precedes the maximum peak and a rear extreme point that is delayed from the maximum peak, respectively.
A probe that receives ultrasonic waves from the outer surface of the object to be inspected and receives the reflected waves; and
An arithmetic unit that calculates the thickness of the internal deposit from the reflected wave, and
(A) An ultrasonic wave is incident from the outer surface of a reference specimen corresponding to an object to be inspected to which no internal deposit is attached, and the reflected wave is received as a reference waveform;
(B) The front time difference Δt1 between the maximum peak and the front extreme point in the reference waveform and the rear time difference Δt2 between the maximum peak and the rear extreme point are stored in advance.
(C) An ultrasonic wave is incident from the outer surface of the object to be inspected, and the reflected wave is received as an inspection waveform;
(D) The conversion time t3 of the maximum peak of the boundary surface echo is converted from the detection time point of the front extreme point of the boundary surface echo included in the inspection waveform and the front time difference Δt1, and the bottom surface echo included in the inspection waveform is converted. The conversion time T3 of the maximum peak of the bottom echo is converted from the detection time of the rear extreme point and the rear time difference Δt2,
(E) The thickness of the internal deposit adhered to the inner surface or back surface of the object to be inspected is calculated from the converted time difference Δt between the converted time points t3 and T3. The inspection object is a power plant or chemical plant piping or plate inspection object,
The thickness measurement apparatus for an internal deposit according to claim 1, wherein the internal deposit is an oxide scale including a steam oxidation scale, a chemical compound, or a resin and rubber, or another chemical compound.   The apparatus for measuring a thickness of an internal deposit according to claim 1, wherein the arithmetic device includes an ultrasonic transmission / reception unit, a control unit, and a display unit. Furthermore, an encoder for detecting positional information of the probe on the outer surface of the inspection object,
2. The thickness of the internal deposit according to claim 1, wherein the arithmetic device displays an image image obtained by color-converting the amplitude information of the reflected wave received by the probe together with the position information. Measuring device. A method for measuring the thickness of internal deposits by ultrasonically measuring the thickness of the internal deposits adhered to the inner surface or back surface of the object to be inspected,
The reflected wave of the ultrasonic wave consists of a boundary surface echo reflected at the boundary surface between the inner surface or back surface of the object to be inspected and the internal deposit, and a bottom surface echo reflected from the inner surface or back surface of the internal deposit,
The boundary surface echo and the bottom surface echo each have a front extreme point that precedes the maximum peak and a rear extreme point that is delayed from the maximum peak, respectively.
(A) An ultrasonic wave is incident from the outer surface of a reference specimen corresponding to an object to be inspected to which no internal deposit is attached, and the reflected wave is received as a reference waveform;
(B) The front time difference Δt1 between the maximum peak and the front extreme point in the reference waveform and the rear time difference Δt2 between the maximum peak and the rear extreme point are stored in advance.
(C) An ultrasonic wave is incident from the outer surface of the object to be inspected, and the reflected wave is received as an inspection waveform;
(D) The conversion time t3 of the maximum peak of the boundary surface echo is converted from the detection time point of the front extreme point of the boundary surface echo included in the inspection waveform and the front time difference Δt1, and the bottom surface echo included in the inspection waveform is converted. The conversion time T3 of the maximum peak of the bottom echo is converted from the detection time of the rear extreme point and the rear time difference Δt2,
(E) A thickness measurement method for an internal deposit, wherein the thickness of the internal deposit adhered to the inner surface or the rear surface of the object to be inspected is calculated from the converted time difference Δt between the converted time points t3 and T3. In (A), a reference waveform is stored,
6. The method of measuring the thickness of an internal deposit according to claim 5, wherein in (D), a reference waveform is displayed so as to overlap the inspection waveform.   6. The method of measuring the thickness of an internal deposit according to claim 5, wherein the front extreme point and the rear extreme point are a peak or a bottom of a reflected wave. Each of the boundary surface echo and the bottom surface echo has three peaks of a front peak, a maximum peak, and a rear peak in order,
The front extreme point is the front peak,
6. The thickness measurement method for internal deposits according to claim 5, wherein the rear extreme point is the rear peak. Detecting position information of the probe on the outer surface of the object to be inspected;
6. The method of measuring the thickness of an internal deposit according to claim 5, wherein an image image obtained by color-converting the amplitude information of the reflected wave received by the probe is displayed together with the position information.