JPS61215908A - Piping inspecting instrument - Google Patents

Abstract

PURPOSE:To measure thickness of the piping with good accuracy nondestructively even in case corrosion or sludge is stuck to the inside of the piping by sampling an echo signal based on multiple reflection of ultrasonic waves. CONSTITUTION:The ultrasonic waves emitted from a transducer 4 make the multiple reflection between the inner and external walls of the piping 2 and the reflected waves are again received by the transducer 4 to output the echo signal corresponding to the ultrasonic waves. This output signal is inputted to an A/D converter 14 via an amplifier 12 and sampled with the prescribed clock frequency and stored in a data memory 16. On the other hand, a control circuit 28 reads the echo signal of the memory 16 and sends out it to a peak detection circuit 22. The number of sampling clock between the peaks detected with a detection circuit 22 is measured with a measurement circuit 24. Then, an average value of the number of sampling clock between the peaks measured with the measurement circuit 24 is calculated with an arithmetic circuit 26 and the thickness of the piping is calculated from the average value.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention is directed to a piping system that allows the thickness of the piping to be accurately and non-destructively measured even if the inside of the piping is corroded or has sludge attached to it. Regarding inspection equipment.

(B) Conventional technology and its problems If the inside of the water supply pipe, cooling or heating pipe is corroded, the pipe may leak, so the thickness of the pipe should be determined in advance to prevent internal corrosion and sludge buildup. It would be convenient if it could be inspected accurately and non-destructively without being affected.

2. Description of the Related Art Conventionally, there is an ultrasonic thickness gauge, for example, as a device for inspecting the thickness of a test object. With this ultrasonic thickness gauge, ultrasonic waves are emitted while the ultrasonic thickness gauge is in contact with piping, changes in the level of the ultrasonic echo are captured by a comparator, etc., and the time of the level change is measured by a frequency counter, etc. The thickness is calculated by measuring. Since this device captures only one level change of the ultrasonic echo, it is easily influenced by external noise, resulting in inaccurate measured data values. However, corrosion and sludge buildup inside the pipes made the measured values unstable, making it difficult to accurately test the thickness of the pipes.

It is an object of the present invention to solve these conventional problems and to enable accurate and non-destructive measurement of the thickness of piping even when the inside of the piping is corroded or sludge is attached.

(c) Means for Solving the Problems In order to achieve the above-mentioned objects, the present invention provides a transducer that sends and receives ultrasonic waves to and from piping, and an echo based on multiple reflections of the ultrasonic waves output from the transducer. A sampling circuit that samples a signal at a predetermined clock frequency; a peak detection circuit that detects each peak based on multiple reflections contained in the echo signal sampled by this sampling circuit; A measuring circuit that measures the number of sampling clocks, an arithmetic circuit that calculates the average value of the number of sampling clocks between the respective peaks measured by the measuring circuit, and calculates the thickness of the pipe from the average value, and this arithmetic circuit. The pipe inspection device includes a data memory that stores data on the calculated pipe thickness.

Therefore, when applying the piping inspection device of the present invention to inspect the thickness of the piping, the transducer is moved along the circumferential direction of the outer wall of the piping, and ultrasonic waves are emitted from the transducer to detect multiple ultrasonic waves from the piping. If an echo signal based on reflection is received, the thickness of the pipe can be measured in the circumferential direction.

(d) Examples Hereinafter, the present invention will be explained in detail based on examples shown in the drawings.

FIG. 1 is a block diagram of the piping inspection device of the present invention. In the figure, numeral 1 denotes a piping inspection device, 2 a piping as an object to be measured, 4 a transducer that sends and receives ultrasonic waves to the piping 2, 6 a coupling capacitor, and 8 an excitation drive for the transducer 4. A pulser that generates a pulse voltage and IO are switches.

Reference numeral 12 denotes an amplifier for analog amplifying the echo signal based on multiple reflections on the inner and outer walls of the pipe outputted from the transducer 4. The amplifier 12 has both logarithmic amplification characteristics and a TGC function whose gain can be varied over time. I4 is amplifier 12
This is a sampling circuit that samples the echo signal output from the circuit at a predetermined clock frequency, and in this example, it is an A/D converter. A data memory 16 stores echo signal data digitized by the A/D converter 14 and pipe thickness data calculated by an arithmetic circuit 24, which will be described later. Further, 18 is a D/A converter that converts the data read from the data memory 16 at the TV scanning speed into analog, and 20 is a TV that displays the analog data as an image.
It's a monitor.

22 is a peak detection circuit that detects each peak based on multiple reflections included in the echo signal sampled at a predetermined clock frequency by the A/D converter 14; 24 is a sampling clock between the peaks detected by the peak detection circuit 22; A measuring circuit 26 is an arithmetic circuit that calculates the average value of the number of sampling clocks between the respective peaks measured by the measuring circuit 24 and calculates the thickness of the pipe from the average value. Further, 28 is a control circuit that controls each of the above-mentioned parts.

Next, the operation of each part when measuring the circumferential thickness of the pipe 2 by applying this pipe inspection device i will be described.

First, as shown in FIG. 2, the transducer 4 comes into contact with the transducer 4 so that the ultrasonic waves radiated therefrom are directed toward the center O of the pipe 2. In this state, a control signal is given to the pulser 8 from the control circuit 28, and the switch IO is turned on to apply the pulse voltage output from the pulser 8 to the transducer 4. As a result, the transducer 4 is excited and driven to emit ultrasonic waves toward the pipe 2. As shown in FIG. 2, the emitted ultrasonic waves cause multiple reflections between the inner and outer walls 80 to 81 of the pipe 2, so the transducer 4 receives echoes of the ultrasonic waves that have caused multiple reflections. The transducer 4 outputs an echo signal corresponding to the received ultrasonic wave. This echo signal is
As shown by the solid line in FIG. 3(a), a signal waveform appears as a signal waveform including peaks based on multiple reflections from the inner and outer walls of the pipe 2, following a strong reflected echo from the outer wall of the pipe 2 immediately after the ultrasonic wave is radiated.

This echo signal output from the transducer 4 is
It is sent to an amplifier 12 via a coupling capacitor 6. The amplifier 12 corrects the intensity attenuation of the echo signal over time and amplifies it so that approximately appropriate sensitivity can be obtained over the measurement time range. The amplified echo signal is sent to the next stage A/
It is output to the D converter 14. The A/D converter 14 samples the echo signal at a predetermined clock frequency and converts the sampled echo signal into a digital signal. Then, the echo signal digitized by the A/D converter 14 is associated with the measurement position of the transducer 4 and the writing position of the echo signal in the echo signal storage section 16a of the data memory 16 according to the address specification of the control circuit 28. is memorized.

The control circuit 28 reads out the echo signal stored in the echo signal storage section 16a at a predetermined timing, and transfers the read echo signal to the peak detection circuit 28.
Send to.

The peak detection circuit 22 data-processes the echo signal to obtain smoothed echo signal data as shown by the broken line in FIG. The echo signal data thus obtained is subtracted, thereby obtaining peak detection data as shown in FIG. 4(b). In this peak detection data, each peak p0 that appears periodically based on multiple reflections is
In addition to ~p5..., this t contains strong echo signals from immediately after the ultrasonic emission to time t0. The period up to this point is set in advance to be excluded from peak detection targets. Therefore, the peak detection circuit 22 detects each peak p that appears periodically. Only the value of -p5... is detected. Each peak value detected by the peak detection circuit 22 is sent to the measurement circuit 24.

The measurement circuit 24 determines each peak interval Δt, ~Δt5, . . . based on each peak value detected by the peak detection circuit 22.
, and the number of sampling clocks present in each peak interval Δ11 to Δt is measured. The measured number of sampling clocks and the values of each peak number are then sent to the arithmetic circuit 26 at the next stage.

The arithmetic circuit 26 calculates each peak p by dividing the sum of the sampling clock numbers between the respective peaks measured by the measuring circuit 24 by the value of each peak number.

The average value of the number of sampling clocks between ~p, . . . is determined, and the thickness of the pipe is calculated from the average value. That is, now, the number of sampling clocks is F1, the thickness of the pipe is T, the sound velocity in the pipe is C1, the average time between each peak p0 to p,... Δt1 the number of sampling clocks between each peak (the number of sampling data) When the average value of (equal) is set to N, the relational expression T=cΔt/ 2 =cN/ 2 F holds true. Therefore, the thickness of the pipe is calculated from this formula.

Data on the thickness of the piping calculated by the arithmetic circuit 26 in this manner is stored in the image data storage section 16b of the data memory 16 via the control circuit 28.

By performing the above operations while sequentially moving the transducer 4 at predetermined distance intervals along the circumferential direction of the outer wall of the pipe 2 (direction of arrow A in Fig. 2), The data is sequentially stored in the image data storage section 16b.

Once the image data is stored in the image data storage section 16b, the image data is read out at the TV scanning speed by the control circuit 28, anamigized by the D/A converter 18, and then output to the TV monitor 20. . This allows the TV
The measured thickness of the pipe is displayed on the monitor 20 as a tomographic image.

In this embodiment, the detection of each peak based on multiple reflections included in the echo signal is digitally processed by the peak detection circuit 22, but as shown in FIG. It can also be processed. That is, after the echo signal output from the transuser 4 is input to the amplifier 512 and amplified, one output from the amplifier 12 is directly sent to the differential amplifier 30, and the other output is sent to the differential amplifier 30 via the smoothing circuit 32. If each amplifier 30 is manually powered, the output of the differential amplifier 30 will be as shown in Figure 3 (
Since the signal waveform of the peak detection data is shown in b), the same result can be obtained even if this signal is sampled at a predetermined clock frequency.

(e) Effects As described above, according to the present invention, the thickness of the pipe is measured by sampling echo signals based on multiple reflections of ultrasonic waves, so that corrosion and sludge can occur inside the pipe. The excellent effect of being able to accurately and non-destructively measure the thickness of the piping without being affected by it, even if there is adhesion or external noise, is exhibited.

[Brief explanation of drawings]

The drawings show embodiments of the present invention, and FIG. 1 is a block diagram of the piping inspection device of the present invention, FIG. 2 is an explanatory diagram of a method for measuring the thickness of piping by applying the same device, and FIG. The figure is a waveform diagram of an echo signal obtained based on multiple reflections of piping, and FIG. 4 is a block diagram of a piping inspection apparatus showing another embodiment. l... Piping inspection device, 2... Piping, 4... Transducer, 14... Sampling circuit (A/D converter), 16... Data memory, 22... Peak detection circuit, 24... ...Measurement circuit, 26...Arithmetic circuit, 28.
...Control circuit.

Claims (1)

[Claims] (1) A transducer that transmits and receives ultrasonic waves to and from piping, a sampling circuit that samples echo signals based on multiple reflections of the ultrasonic waves output from the transducer at a predetermined clock frequency, and a peak detection circuit that detects each peak based on multiple reflections included in the echo signal; a measurement circuit that measures the number of sampling clocks between each peak detected by this peak detection circuit; A calculation circuit that calculates the average value of the number of sampling clocks between each peak and calculates the thickness of the pipe from the average value, and a data memory that stores data on the pipe thickness calculated by this calculation circuit. Characteristic piping inspection equipment.