JP3501948B2 - Ultrasonic corrosion diagnostic method and its equipment. - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic corrosion diagnostic method, and more particularly to a method for ultrasonically diagnosing a surface of an object to be diagnosed such as a casing of a sewage pump or a rainwater pump manufactured by casting without flattening the surface. The present invention relates to an ultrasonic corrosion diagnostic method for contacting a sensor that projects or receives a sound wave to diagnose the degree of corrosion or deterioration of the back surface of the object to be diagnosed.

[0002]

2. Description of the Related Art Cast iron, carbon steel and the like are used as structural materials for casings and pumping pipes of sewage pumps, rainwater pumps, etc., and the number of aging equipment for which the equipment has been installed for more than 20 years is increasing. These devices are the heart of the sewer line, which is indispensable for daily life, so it is important to perform regular inspections and diagnoses to prevent accidents and breakdowns, and take measures such as repairs and replacements as necessary. Is.

Hydrogen sulfide is generated from domestic wastewater (dirt water) handled by the equipment, and the installation environment of the equipment is in a state where corrosion (deterioration) is likely to occur. When the paint peels off and corrosion starts in a part of the structural material, the corrosion rapidly spreads throughout and progresses deep inside the structural material. If the progress of this corrosion is left as it is, the strength of the structural material gradually decreases and it may progress to a large destruction accident. Therefore, it is necessary to grasp the corrosion state of the equipment through regular inspection and diagnosis.

The conventional method of inspecting and diagnosing the corrosion state of the inner surface (back surface) of the structural material is to disassemble the equipment and make a visual judgment. This method is effective in accurately grasping and confirming the actual situation, but it cannot be performed while the equipment is in operation because the equipment must be disassembled.

Therefore, an ultrasonic diagnostic method has come to be used as a nondestructive inspection method.

In this method, a sensor for projecting or receiving ultrasonic waves is brought into contact with the surface of the object to be diagnosed to diagnose the degree of corrosion or deterioration of the back surface of the object to be diagnosed.

That is, an ultrasonic wave having an amplitude P is projected onto the surface of the object to be diagnosed, and the thickness P of the object to be diagnosed is calculated from the amplitude Px of the reflected wave of the ultrasonic wave in the object to be diagnosed and the time when the reflected wave is obtained. x is obtained, the attenuation coefficient α of the ultrasonic wave is obtained from these, and a master curve representing the relationship between the thickness and the reflected wave of the object to be diagnosed, which is obtained in advance with a sample using the constituent material of the object to be diagnosed, is obtained. By using the damping coefficient, the corrosion condition on the back surface of the object to be diagnosed is diagnosed.

In the master curve, if the attenuation coefficient α of the ultrasonic wave with respect to the thickness x of the object to be diagnosed is larger than that of a healthy object to be diagnosed, the unevenness of the back surface is large, that is, the back surface is corroded. Determine that

As an introduction to such an ultrasonic diagnostic method, "Ultrasonic flaw detection method" (edited by the Japan Society for the Promotion of Science, Steelmaking 19th Committee, December 1976, published by Nikkan Kogyo Shimbun) Article titled "6.2 Attenuation Measurement" (p
p301-321).

[0010]

According to the ultrasonic diagnostic method, the thickness of the sound layer can be measured. The exact thickness of the object to be diagnosed manufactured by casting is not clear due to the processing accuracy of the mold, and the thickness at the time of casting often differs from the designed value. If the thickness immediately after casting is not known, in the diagnosis using the above master curve, when the thickness of the obtained sound layer is significantly lower than the design value,
It can be determined that the entire equipment is in a dangerous state and structural materials need to be replaced rather than repaired.

However, when the thickness of the obtained sound layer is about the design value, the degree of progress of corrosion depends on whether the accuracy of the mold is high or not if the thickness of the sound layer before the corrosion is not known. It cannot be determined whether it has become thin. Therefore, it is not accurate to judge the degree of progress of corrosion based on the thickness of the sound layer to judge the necessity of repair.

Further, the object to be diagnosed manufactured by casting has a cast surface with unevenness on all surfaces due to the processing accuracy of the mold and the like. Therefore, if the sensor is directly contacted with the structural material provided with a coating for rust prevention or protection and ultrasonic waves are transmitted / received, it will be attenuated by the unevenness of the surface on the side where the sensor is contacted. It is not possible to distinguish whether the attenuation is due to unevenness on the surface or due to corrosion on the back surface. If the attenuation of the ultrasonic waves is caused by the back surface corrosion, the degree of progress of the back surface corrosion will be greatly judged.

Therefore, the surface of the structural material with which the sensor is in contact must be made smooth. Measurement accuracy can be obtained by smoothing, but since a coating for rust prevention and protection is provided on the surface of the structural material, a coating for rust prevention and protection is applied to the smoothed location after the diagnostic work. Need to be provided. In that case, a color difference between the newly applied coating and the previous coating often occurs, and the appearance of the surface of the structural material is impaired.

Therefore, an object of the present invention is to accurately contact the sensor directly with a structural material provided with a coating film for rust prevention and protection without smoothing the surface of the structural material to accurately measure the progress of corrosion of the back surface. An object of the present invention is to provide an ultrasonic corrosion diagnostic method and a device therefor capable of determining

[0015]

The feature of the present invention for achieving the above object is to project an ultrasonic wave on the surface of an object to be diagnosed and obtain a reflected wave of the ultrasonic wave on the back surface of the object to be diagnosed. From the master curve showing the relationship between the thickness of the object to be diagnosed and the reflected wave, which is obtained in advance by the sample of the constituent material of the object to be diagnosed by the attenuation coefficient of the ultrasonic wave in the object to be diagnosed In the ultrasonic corrosion diagnosis method for diagnosing the corrosion state on the back surface of the object to be diagnosed, a sensor is brought into contact with the surface of the object to be diagnosed through a delay material to ensure the soundness of the coating film on the surface and the object to be diagnosed. Amplitude of reflected wave at interface with layer ( PF
The same can be obtained for the sample with the front and back surfaces smoothed in 1 )
Interface echo ratio (PF1 / PF
0) was obtained, and the interface echo ratio (PF1 / PF0) from front and back surfaces of the smooth amplitude (PR1) of the reflected wave at the rear surface of該被diagnostic product
Amplitude of reflected wave ( PRX ) similarly obtained for the sample
To the backside echo ratio ( PR1 / PRX ) , which is the ratio to to obtain the amplitude, the back Men'e code ratio the amplitude of the reflected wave
It is to diagnose the corrosion state on the back surface of the object to be diagnosed from the master curve by correcting the inverse number ( PRX / PR1 ) of ( PR1 / PRX ) and the thickness of the object to be diagnosed and the corrected amplitude of the reflected wave.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on the embodiments shown in the drawings. FIG. 1 shows, as an embodiment of the present invention, a situation in which ultrasonic waves are used to diagnose the degree of progress of corrosion on the inner surface of a casing 1 of a pump that is in use.

The casing 1 comprises a casing body 1a which is a sound layer of cast iron, a coating film 1b provided on the outer surface of the casing body 1a, and a corrosion layer 1c formed on the inner surface (the back surface when viewed from the surface of the casing body 1a). To do. Sewage 2 is flowing in the casing 1 because the pump is in use.

Ultrasonic sensors (hereinafter abbreviated as sensors) 3 and 4 are provided on the coating film 1b. Both the sensors 3 and 4 are connected by a connecting member 5 with a certain interval, and an operator (not shown) is shown in FIG. 1 in order to make a diagnosis on the coating film 1b.
In, both sensors 3 and 4 are moved leftward or rightward. A delay material 6 is fixed to the sensor 3 on the side of the coating film 1b. Reference numerals 7 and 8 are transmitters for sending ultrasonic pulses having the same amplitude to the sensors 3 and 4, respectively.
Although the ultrasonic wave is projected onto the sensor 1, the sensor 4 directly projects the ultrasonic wave onto the coating film 1b because no delay material is provided. 9, 10
Is a receiver that receives reflected waves from the casing 1 for the ultrasonic waves emitted from the sensors 3 and 4, respectively.

Reference numerals 11 and 12 are A / D converters for digitizing the reflected waves from the casing 1 obtained by the receivers 8 and 9, and 13 and 14 are waveform memories for storing the digitized reflected waves. , 15 and 16 are displacement gauges for measuring the positions of the sensors 3 and 4 on the casing 1 through the connecting members 17 and 18, and 19 and 20 are the positions of the sensors 3 and 4 obtained by the displacement gauges 15 and 16. A position memory for storing data. 21 is the waveform memories 13 and 14 and the position memory 1
A computer (hereinafter abbreviated as a personal computer) that obtains data from 9 and 20 and performs processing, and outputs the processing result and the like from the monitor 22 and the printer 23 as appropriate.

Either of the sensors 3 and 4 may come first,
Where one of the sensors projects ultrasonic waves, the other sensor always projects ultrasonic waves. The two sensors 3 and 4 are integrated by the connecting member 5 because when the two sensors 3 and 4 are moved in a straight line at a constant interval by the connecting member 5, the two sensors 3 and 4 move to the same position on the casing 1. To project sound waves,
This is because the work becomes easy.

The sensor 3 handles the reflected wave at the boundary between the casing body 1a, which is a sound layer of cast iron, and the coating film 1b provided on the outer surface of the received wave, and the sensor 4
Is a casing body 1a which is a sound layer of cast iron in the received wave
The reflected wave at the boundary surface between the corrosion layer 1c and the corrosion layer 1c is treated. Therefore, the sensor 3 indicates the state of the surface of the casing body 1a as
Further, the sensor 4 can see the state of the back surface of the casing body 1a.

The personal computer 21 stores the master curve data shown in FIGS. 2 and 3 for each constituent material of the object to be diagnosed. FIG. 2 shows a plurality of samples in which the same constituent material as that of the casing 1 is used, the surface of which is changed in roughness and the back surface thereof is made smooth, and the amplitude PF1 of the reflected wave obtained by the sensor 3 is obtained by the sensor 4 on the horizontal axis. It shows an example of a master curve for correcting the actual measurement value, which is represented by plotting the amplitude PR1 of the reflected wave on the vertical axis.

In FIG. 2, PF0 and PRX are the amplitudes of the reflected waves obtained by both sensors 3 and 4 with respect to the sample whose front and back surfaces are both smoothed. The reason for taking the ratio (echo ratio) for each amplitude is the sample. This is to eliminate the influence due to the thickness of. The respective amplitudes PF0 and PRX indicate that the casing 1 is in an ideal state in which the casing 1 is not corroded and the unevenness of the casting surface is extremely small. Therefore, hereinafter, the respective amplitudes PF0 and PRX are referred to as reference echo heights. The inventors of the present invention can confirm that the master curve MC2 shown in FIG. 2 can be expressed by the following formula even if the composition of the constituent material of the object to be diagnosed is changed and the constants A to C are changed depending on the constituent material. It was PR1 / PRX = A (PF1 / PF0) ² + B (PF1 / PF0) + C (Equation 1) In FIG. 2, the amplitude PF1 of the reflected wave obtained by the sensor 3 indicates the degree of surface roughness. Echo ratio PF at 3
The fact that 1 / PF0 is small means that the surface is rough, and conversely, as the echo ratio PF1 / PF0 approaches 1, the surface becomes flatter. Echo ratio PR1 / P at sensor 4
Since the RX and the echo ratios PF1 / PF0 in the sensor 3 have a correlation, the echo ratio P in the sensor 4
R1 / PRX can be estimated from the echo ratios PF1 / PF0 at the sensor 3, that is, the degree of surface roughness.

The present invention utilizes this tendency, and the combined attenuation in the forward and backward paths of ultrasonic waves due to surface roughness is corrected by the echo ratio PR1 / PRX obtained from the echo ratio PF1 / PF0 at the sensor 3. Assuming that an ultrasonic wave is projected from this virtual surface, the degree of roughness of the rear surface (degree of progress of corrosion) is determined. That is, it can be said that the smaller the echo ratio PR1 / PFX in FIG. 2, the rougher the surface and the more the ultrasonic waves are attenuated in the round trip. Therefore, the reciprocal of the echo ratio PR1 / PFX (PRX / PR1) is measured by the sensor 4. By multiplying by, it can be considered that the ultrasonic wave is projected from the smooth surface and the reflected wave on the back surface is obtained by the sensor 4 on the smooth surface. Therefore,
Even if the coating layer 1b is not peeled off and the surface of the sound layer 1a is not ground and smoothed, the degree of progress of corrosion on the back surface can be determined.

FIG. 3 shows a value obtained by previously correcting the amplitude P1a of the reflected wave measured by the sensor 4 for the thickness L3 of the healthy layer by the sensor 4 using the sample made of the constituent material of the object to be diagnosed in advance by the reciprocal. When the relationship between the ratio of P1 and the amplitude P0 of the reflected wave (measured echo ratio P1 / P0) of the sample with smooth front and back surfaces is sound, the initial state where corrosion started, the state where corrosion further progressed, and the severe corrosion The master curves MC31 to MC33 for diagnosing the degree of progress of corrosion are shown in a diagram with the damping coefficient αn so that the received state can be distinguished.

The echo ratio is used to eliminate the influence of the thickness, as in the case of FIG.

The above echo ratios and corrosion diagnosis will be specifically described below with reference to the flow chart shown in FIG. First, the measurement of the thickness L2 of the coating film 1b at an arbitrary position of the casing 1 shown in FIG. 1 with the sensor 3 will be described with reference to FIG.

FIG. 4A shows, as a model, a situation in which the thickness L2 of the coating film 1b is measured by the sensor 3 via the delay material 6. Since the delay member 6 is designed, its constituent material and thickness L1 are known values.

In step (hereinafter abbreviated as S) 1 shown in FIG. 9, the sensor 3 is moved to the measurement position, and the ultrasonic wave T is emitted from the sensor 3.
1, and the sensor 3 receives the reflected wave R2 from the interface between the coating film 1b and the sound layer 1a. Although the reflected wave at the interface between the delay material 6 and the coating film 1b is also received, it is assumed that the surface of the coating film 1b is rough, and reflection at the interface between the delay material 6 having a smooth contact surface and the atmosphere. Take advantage of the waves. The reflected wave is referred to as a wave R1, and the waveforms of the ultrasonic wave T1 and the reflected waves R1 and R2 from the respective interfaces are shown in FIG. 4B.

In FIG. 4B, PF1a and PF1 are the amplitudes (echo heights) of the reflected waves R1 and R2, respectively.

The thickness L1 of the delay member 6 is a known value, but if it is desired to confirm it in terms of processing accuracy, the ultrasonic wave velocity c and the reflected wave R1 determined by the constituent materials thereof were obtained. It can be easily obtained (L1 = C × t / 2) from the time (road length) t.

As shown in FIG. 4 (b), the sensor 3 performs R2
By measuring, the thickness L2 of the coating film 1b and the amplitude PF1 can be obtained from the waveform (S2 in FIG. 9).

Next, the echo ratios PF1 / PF0 relating to the coating film 1b shown in FIG. 2 will be described with reference to FIG. The reference echo height PF0 is the amplitude of the reflected wave when the surface of the sound layer 1a is smooth as described with reference to FIG. Figure 5
(A) shows the situation as a model. FIG. 5B shows the waveform of the reference echo (reference reflected wave) R2O matched with FIG. 4B. The height PF0 of the reference echo R2O has almost no attenuation because the surface of the sound layer 1a is smooth, and is therefore a value larger than the measured value PF1.

The height PF0 of the reference echo R2O is shown in FIG.
From the sample prepared in advance as the model of (a), one in which the material and thickness of the sound layer 1a and the coating film 1b are the same is selected, and the ultrasonic wave T1 having the same sound pressure as in the case of FIG. 4 is projected from the sensor 3. Although it may be measured by measuring, the measured value and the design value in FIG. 4, the acoustic impedance of each material, the internal attenuation coefficient, the ultrasonic wave T
It may be calculated from the attenuation at each interface and the internal attenuation by a known method using the sound pressure of 1 (S3 in FIG. 9).

By obtaining the height PF0 of the reference echo R2O, the echo ratio PF1 / for the coating film 1b by the sensor 3 is obtained.
PF0 is obtained. Therefore, this echo ratio PF1 / PF
0 is used to obtain the echo ratio PR1 / PRX at the sensor 4 from the master curve of FIG. 2 prepared in advance or the equation 1 (S4 of FIG. 9).

Next, as shown in FIG. 6, the sensor 4 measures the same position on the casing 1 where the sensor 3 measured (S5 to S6 in FIG. 9). As shown in FIG. 1, the sensor 4
Is in direct contact with the coating film 1b of the casing 1, and unlike the case of the sensor 3, there is no delay material.

FIG. 6A shows a model of the measurement situation by the sensor 3, as in FIG. 5A. Sensor 4
Among the ultrasonic waves projected from, those reaching the back surface are indicated by T2, and the reflected wave R3 is received by the sensor 4. The ultrasonic wave T2 and the reflected wave R3 have the waveforms shown in FIG. 6B, and the amplitude (echo height) of the reflected wave R3 received by the sensor 4 is P
1a. Since the thickness L2 of the coating film 1b is known by the measurement by the sensor 3, the thickness L3 of the sound layer 1a can be known from the time until the reflected wave R3. Like the thickness L2 of the coating film 1b, the thickness L3 of the sound layer 1a can also be accurately calculated by calculation from the sound velocity, the road length, etc. (S7 in FIG. 9).

Since the interface between the coating film 1b and the sound layer 1a is rough, the ultrasonic wave T2 and the reflected wave R3 are attenuated when passing through this interface. Therefore, the echo height P1a of the reflected wave R3 is the back surface of the casing 1, that is, the sound layer 1a and the corrosion layer 1c.
It does not accurately reflect the roughness of the interface.

Then, as shown in FIG. 7A, the coating film 1
The amplitude of the reflected wave R3 when there is no roughness at the interface between b and the sound layer 1a is P1, and this is obtained from the knowledge on which the present invention is based, shown in FIG.

As for the casing 1 being actually measured, the echo ratio PR1 / PRX at the sensor 4 is obtained from the master curve of FIG. Therefore, by multiplying the echo height P1a of the reflected wave R3 by using the reciprocal PRX / PR1 as a correction value, the reflected wave when the interface between the coating film 1b and the sound layer 1a is not rough as shown in FIG. 7B. The amplitude P1 of R3 is obtained (S8 in FIG. 9).

In FIG. 7 (b), the waveform R30 shows the reflected wave R3 corrected by the reciprocal PRX / PR1. As in the conventional case, the surface of the casing 1 is ground and smoothed, and the sensor is directly ground to the ground surface. This waveform R30 can be obtained by contacting with and contacting with, but in the present invention, since the measurement is performed without grinding, the actually measured waveform is waveform R.
It is 3.

Next, in order to eliminate the influence due to the thickness of the sound layer 1a, the echo ratio is obtained for the waveform R30.

As shown in FIG. 8A, the reference echo for obtaining the echo ratio is made of the same material as the thicknesses L2 and L3 of the coating film 1b and the sound layer 1a prepared in advance, and the interface is smooth. The sensor 4 is brought into contact with the sample, or the measured value or design value in FIG. 6 and the acoustic impedance of each material, the internal attenuation coefficient,
The sound pressure of the ultrasonic wave T1 may be used to calculate from the attenuation at each interface and the internal attenuation by a known method (S9 in FIG. 9). The reference echo waveform R4 obtained by these methods and its amplitude are P
8 (b) in comparison with the echo waveform R30 in which 0 is corrected.
It was shown to.

Since the echo ratio P1 / P0 for the sound layer 1a by the sensor 4 is obtained (S10 in FIG. 9),
The thickness L3 of the sound layer 1a obtained by the actual measurement of FIG.
The degree of progress of corrosion of the corrosion layer 1c is determined by the personal computer 21 in which the master curves MC31 to MC33 shown in are stored in advance.

In FIG. 3, master curves MC31 to MC31
In the MC 33, the damping coefficient αn in the sound layer 1a is arbitrarily determined from experience as α1, α2, and α3, respectively. If the relationship between the thickness L3 of the sound layer 1a and the echo ratio P1 / P0 is above the position of the master curve MC31, the casing 1 is healthy without corrosion. If it is between the master curve MC31 and the master curve MC32, the casing 1 is corroded. It can be determined that the initial state of the start of the process, the state where the corrosion is further progressed between the master curve MC32 and the master curve MC33, and the state where the corrosion has been performed if it is below the master curve MC33.

That is, each master curve MC31 to MC3
3 can be generalized and expressed by the following formula. P1 / P0 = exp (−αn · 2 · L3) (Equation 2) Each attenuation coefficient αn can be expressed by the following equation by expanding this Equation 2. αn = − (1/2 · L3) · (lnP1 / P0) (Equation 3) The thickness L3 and the echo ratio P of the sound layer 1a obtained by the above measurement and the like.
The damping coefficient α in the casing 1 is obtained by inserting 1 / P0 into the following equation. α = − (½ · L3) · (lnP1 / P0) (Equation 4) The attenuation coefficient α obtained as a result of the calculation is used as the master curve M.
The damping coefficient αn of C31 to MC33 is sequentially compared, and if the damping coefficient α1 of the master curve MC31 is smaller than the damping coefficient α1 of the master curve MC31, the sound state is normal, the initial state between the damping coefficients α1 and α2 of the master curves MC31 and MC32, the master curve MC32 , MC33 of the attenuation coefficient α2, α3, corrosion progressed, the master curve MC33 of the attenuation coefficient α
If it is larger than 3, the degree of progress of the above-mentioned corrosion is judged as severe corrosion (S11 of FIG. 9).

In the above description, an arbitrary point of the casing 1 has been described, but since it is customary to measure corrosion at a plurality of points to make a corrosion diagnosis, as shown in FIG. If 4 and 4 are integrated and moved, and the data of the amplitude and the position are sequentially captured, it is possible to determine the progress degree of corrosion in the inside (rear surface) of a device in operation while associating the position with the personal computer 21. it can.

If the operator can specify the position to be measured, stop using the two sensors 3 and 4 and
The delay material may be attached to and detached from each sensor, and the state of roughness on the surface of the object to be diagnosed (casing) may be grasped.

Further, although the master curves of FIGS. 2 and 3 are displayed by the echo ratio, the reference echo may not be used if there is no concern about the influence of the thickness.

[0050]

As described above, according to the present invention, the sensor is directly brought into contact with the structural material provided with the coating film for rust prevention and protection without smoothing the surface of the structural material, and the back surface is accurately formed. The degree of progress of corrosion can be determined.

[Brief description of drawings]

FIG. 1 is a diagram showing a situation in which a degree of progress of corrosion of an inner surface of a casing 1 of a pump used in an ultrasonic corrosion diagnostic apparatus according to an embodiment of the present invention is diagnosed.

FIG. 2 is a diagram showing an example of a master curve for correcting actual measurement values stored in a personal computer in the ultrasonic corrosion diagnostic apparatus shown in FIG.

3 is a diagram showing an example of a master curve for diagnosing a degree of corrosion progress stored in a personal computer in the ultrasonic corrosion diagnostic apparatus shown in FIG.

4 is a diagram showing a situation in which the thickness of a coating film at an arbitrary position of the casing shown in FIG. 1 is measured by a sensor via a delay material.

5 is a diagram showing a situation in which an echo ratio for a coating film is obtained based on measurement results obtained by the sensor shown in FIG.

FIG. 6 is a diagram showing a situation in which the thickness of the sound layer in the casing is measured by a sensor at an arbitrary position measured in FIG. 4 without interposing a delay material.

FIG. 7 is a diagram illustrating the amplitude of a reflected wave when there is no roughness at the interface between the coating film and the sound layer in FIG.

8 is a diagram showing a situation in which an echo ratio for a sound layer in a casing is obtained based on a measurement result obtained by the sensor shown in FIG.

FIG. 9 is a flow chart when the degree of progress of corrosion on the inner surface of the casing 1 of the pump being used is diagnosed by the ultrasonic corrosion diagnostic apparatus shown in FIG.

[Explanation of symbols]

1 ... Casing 1a ... Casing body (healthy layer) 1b ... Coating film 1c ... Corrosion layer 3, 4 ... Ultrasonic sensor 5 ... Connecting member 6 ... Delay material 7, 8 ... Transmitter 9, 10 ... Receiver 11, 12 ... AD converter 13, 14 ... Waveform memory 15, 16 ... Displacement meter 17, 18 ... Connecting material 19, 20 ... Position memory 21… Computer (personal computer) 22 ... Monitor 23 ... Printer

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Tetsuya Tominaga Tetsuya Tominaga 2-8-4 Jinritsu Higashi 2-chome, Tsuchiura City, Ibaraki Prefecture Hiratsuno Engineering Co., Ltd. Tsuchiura Works (72) Inventor Toshiyuki Yamaguchi Jinritsu Higashi Tsuchiura City, Ibaraki Prefecture No. 28-4, Nititsu Techno Engineering Co., Ltd., Tsuchiura Works (56) Reference JP-A-5-172794 (JP, A) JP-A-2-143158 (JP, A) JP-A-3-84407 (JP , A) JP-A 64-46609 (JP, A) JP-A-3-200061 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 29/00-29/28

Claims (3)

(57) [Claims] 1. An ultrasonic wave is projected onto the surface of the object to be diagnosed, a reflected wave of the ultrasonic wave on the back surface of the object to be diagnosed is obtained, and an attenuation coefficient of the ultrasonic wave at the object to be diagnosed is obtained. In the ultrasonic corrosion diagnosis method for diagnosing the corrosion state on the back surface of the object to be diagnosed from the master curve representing the relationship between the thickness and the reflected wave of the object to be diagnosed, which is obtained in advance by the sample of the constituent material of the object to be diagnosed, The sensor is brought into contact with the surface of the object to be diagnosed through a delay material to smooth the front and back surfaces of the amplitude ( PF1 ) of the reflected wave at the interface between the coating film on the surface and the healthy layer of the object to be diagnosed. Tried
Is the ratio of the amplitude of the reflected wave obtained in the same way
That the interface echo ratio to give (PF1 / PF0), said interface echo ratio (P
F1 / PF0) to the amplitude of the reflected wave on the back of the object to be diagnosed
( PR1 ) samples obtained by smoothing the front and back surfaces were obtained in the same manner.
The backside echo ratio ( PR1 / PRX ) , which is the ratio to the amplitude ( PRX ) of the reflected wave to be generated, is obtained, and the sensor is brought into contact with the surface without a delay material, and the reflected wave of the ultrasonic wave on the backside is used to to obtain the amplitude of the thickness and the reflection wave of the diagnostic object, the inverse of the amplitude of the reflected wave back Men'e code ratio (PR1 / PRX) (PRX / PR
An ultrasonic corrosion diagnostic method, wherein the corrosion condition on the back surface of the diagnostic object is diagnosed from the master curve by the thickness of the diagnostic object and the corrected amplitude of the reflected wave corrected in 1 ) . 2. The ultrasonic corrosion diagnostic method according to claim 1, wherein the master curve has an amplitude (P1) of the reflected wave obtained from the back surface, and the amplitude of the reflected wave obtained from the back surface of the sample whose front and back surfaces are smooth. An ultrasonic corrosion diagnostic method characterized in that it is displayed as a relationship between the ratio (P1 / P0) to (P0) and the thickness of the object to be diagnosed. 3. An ultrasonic wave is projected on the surface of the object to be diagnosed, a reflected wave of the ultrasonic wave on the back surface of the object to be diagnosed is obtained, and an attenuation coefficient of the ultrasonic wave at the object to be diagnosed is obtained. A device for diagnosing the corrosion state on the back surface of the object to be diagnosed from a master curve representing the relationship between the thickness and the reflected wave of the object to be diagnosed, which is obtained in advance from a sample of the constituent material of the object to be diagnosed.
A first sensor for projecting an ultrasonic wave to a surface of an object to be diagnosed through a delay material and receiving a reflected wave from the surface, and an ultrasonic wave directly contacting the surface without a delay material A second sensor for projecting light and receiving the reflected wave from the back surface, and
Equipped with a judgment means for diagnosing the corrosion state on the back of the diagnostic object
Then, from the measurement by the first sensor , the amplitude of the reflected wave at the interface between the coating film on the surface and the sound layer of the object to be diagnosed
( PF1 ) sample obtained by smoothing the front and back surfaces was obtained in the same manner.
Obtaining interface echo ratio (PF1 / PF0) is the ratio to the amplitude (PR0) of the reflected wave, against the amplitude (PRX) of the reflected wave at the rear surface of該被diagnostic object from the interface echo ratio (PF1 / PF0)
Together to obtain the back surface echo ratio (PR1 / PRX) is that ratio,
Obtaining the thickness of the object to be diagnosed and the amplitude of the reflected wave on the back surface from the measurement by the second sensor, the amplitude of the reflected wave being the reciprocal of the echo ratio ( PR1 / PRX ) on the back surface ( PRX / PR1). ) by obtaining the amplitude of the reflected wave corrected, and to diagnose the corrosion situation in the rear surface of the diagnostic object from the master curve by the amplitude of the thickness of該被diagnostic object and corrected the reflected wave
An ultrasonic corrosion diagnostic device characterized in that