Piping inspection equipment

Abstract

To provide a pipe inspection device that can improve the measurement accuracy of pipe thickness without using a sensor that detects environmental changes.SOLUTION: A pipe inspection device comprises a plurality of ultrasonic sensors 11 fixed to am outer surface 2 of a pipe 1 via an adhesive 3, and an ultrasonic inspection device 12 that acquires a plurality of waveform signals using the plurality of ultrasonic sensors 11. The ultrasonic inspection device 12 does not calculate a thickness of the pipe 1 at the position of one ultrasonic sensor 11 when the reception time of the inner surface echo is less than the threshold value t0 and its rate of change exceeds the threshold value u0 in one waveform signal acquired from one ultrasonic sensor 11 of the two ultrasonic sensors 11 adjacent to each other, and the reception time of the inner surface echo is less than the threshold value t0 and its rate of change exceeds the threshold value u0 in the other waveform signal acquired from the other ultrasonic sensor 11,.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a pipe inspection device that measures the thickness of a pipe. [Background technology]

[0002] The inner surface of plant pipes can be eroded by the high-temperature fluid flowing inside, potentially resulting in thinning of the pipe wall. For this reason, it has been proposed to permanently install an ultrasonic sensor on the outer surface of the pipe (provided that, if there is insulation covering the outer surface of the pipe, the sensor should be positioned inside the insulation) and use the ultrasonic sensor to measure the thickness of the pipe (see, for example, Patent Document 1). The monitoring system in Patent Document 1 includes an ultrasonic sensor (thin-film sensor) fixed to the outer surface of the pipe with an adhesive, and an ultrasonic flaw detector connected to the ultrasonic sensor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-113752 Summary of the Invention [Problem to be solved by the invention]

[0004] Although not explicitly stated in Patent Document 1, an ultrasonic flaw detector transmits ultrasonic waves from an ultrasonic sensor toward the inner surface of a pipe, and the ultrasonic waves from the pipe are received by the ultrasonic sensor and converted into a waveform signal. The waveform signal includes an inner surface echo corresponding to the ultrasonic waves reflected by the inner surface of the pipe. The ultrasonic flaw detector obtains the reception time of the inner surface echo from the waveform signal (in other words, the round-trip time of the ultrasonic waves between the ultrasonic sensor and the inner surface of the pipe), and calculates the thickness of the pipe based on this.

[0005] However, if the state of the fluid inside the pipe (specifically, the flow rate and temperature) changes due to, for example, a load fluctuation in the plant, the temperature of the pipe changes, and the speed of sound in the pipe also changes. This causes the reception time of the inner surface echo to change even if the pipe thickness does not change. Therefore, unless a sensor that detects environmental changes such as temperature changes is used, the accuracy of pipe thickness measurement may decrease.

[0006] An object of the present invention is to provide a pipe inspection device that can improve the accuracy of measuring the thickness of a pipe without using a sensor that detects changes in the environment. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides a pipe inspection device comprising a plurality of ultrasonic sensors fixed to the outer surface of a pipe via an adhesive, and an ultrasonic inspection device that transmits ultrasonic waves from the plurality of ultrasonic sensors toward the inner surface of the pipe and acquires a plurality of waveform signals obtained by receiving and converting the ultrasonic waves from the pipe by the plurality of ultrasonic sensors. The ultrasonic inspection device calculates the thickness of the pipe at the position of one of the ultrasonic sensors based on the reception time of the inner surface echo in one waveform signal acquired from one of two adjacent ultrasonic sensors when the reception time of the inner surface echo in the one waveform signal is equal to or less than a predetermined first threshold and the reception time of the inner surface echo in the other waveform signal acquired from the other ultrasonic sensor exceeds the first threshold, and calculates the thickness of the pipe at the position of the one waveform signal when the reception time of the inner surface echo in the one waveform signal is equal to or less than the first threshold and the rate of change of the inner surface echo is equal to or less than a predetermined second threshold and when the reception time of the inner surface echo in the other waveform signal is equal to or less than the first threshold and the rate of change of the inner surface echo in the other waveform signal is equal to or less than the second threshold. ReceptionThe thickness of the pipe at the position of one of the ultrasonic sensors is calculated based on time, and if, in one of the waveform signals, the reception time of the inner surface echo is less than the first threshold and the rate of change thereof exceeds the second threshold, and, in the other waveform signal, the reception time of the inner surface echo is less than the first threshold and the rate of change thereof exceeds the second threshold, the thickness of the pipe at the position of one of the ultrasonic sensors is not calculated. [Effects of the Invention]

[0008] According to the present invention, it is possible to improve the accuracy of measuring the thickness of a pipe without using a sensor that detects changes in the environment. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram illustrating a configuration of a piping inspection device according to an embodiment of the present invention. [Figure 2] 3 is a flowchart showing the procedure of arithmetic control of the ultrasonic inspection device according to one embodiment of the present invention. [Figure 3] FIG. 2 is a diagram showing an example of pipe wall thinning in one embodiment of the present invention, along with waveform signals from two corresponding ultrasonic sensors. [Figure 4] 10 is a diagram showing another example of pipe wall thinning in an embodiment of the present invention, along with waveform signals from two corresponding ultrasonic sensors. FIG. [Figure 5] 10 is a flowchart showing a procedure for notification control of an ultrasonic inspection device according to an embodiment of the present invention. [Figure 6] FIG. 10 is a diagram illustrating an example of adhesive peeling in one embodiment of the present invention, along with corresponding waveform signals from two ultrasonic sensors. [Figure 7] 10 is a diagram illustrating another example of adhesive peeling in one embodiment of the present invention, along with waveform signals from two corresponding ultrasonic sensors. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the present invention will be described with reference to the drawings.

[0011] FIG. 1 is a schematic diagram showing the configuration of a piping inspection device according to this embodiment.

[0012] The piping inspection device of this embodiment includes a plurality of ultrasonic sensors 11 fixed to the outer surface 2 of a plant pipe 1 via adhesive 3 (see FIG. 3(a) and the like described below), an ultrasonic inspection device 12 that inputs and outputs signals to and from the plurality of ultrasonic sensors 11, and a display device 13 (display) connected to the ultrasonic inspection device 12. Note that while FIG. 1 shows an example in which the plurality of ultrasonic sensors 11 and the ultrasonic inspection device 12 are connected by cables, this is not limiting. For example, the cable on the ultrasonic sensor 11 side and the cable on the ultrasonic inspection device 12 side may be separated, coils may be provided at the tips of the cables, and signals may be transmitted using electromagnetic induction between the coils.

[0013] The ultrasonic sensors 11 are permanently installed at predetermined distances from one another, for example, in the axial direction (vertical direction in FIG. 1) of the pipe 1. Each ultrasonic sensor 11 is, for example, a vertical probe having one piezoelectric element (i.e., a piezoelectric element for transmitting and receiving), a vertical probe having two piezoelectric elements (i.e., a piezoelectric element for transmitting and receiving), or an array probe having a large number of piezoelectric elements.

[0014] The ultrasonic inspection device 12 has a switching unit 14, a pulser 15, a receiver 16, a signal processing unit 17, and a storage unit 18. The switching unit 14 is composed of a multiplexer or the like, the signal processing unit 17 is composed of a processor or the like that executes processing according to a program, and the storage unit 18 is composed of a hard disk, memory, or the like.

[0015] The switching unit 14 of the ultrasonic inspection device 12 sequentially connects the multiple ultrasonic sensors 11 to the pulser 15 and receiver 16. The pulser 15 outputs a pulse signal (electrical signal) to the ultrasonic sensor 11 via the switching unit 14. The piezoelectric element of the ultrasonic sensor 11 vibrates in response to the pulse signal and transmits ultrasonic waves toward the inner surface 4 of the pipe 1. The piezoelectric element of the ultrasonic sensor 11 receives ultrasonic waves from the pipe 1, converts the received ultrasonic waves into waveform signals (electrical signals), and outputs them to the ultrasonic inspection device 12. The receiver 16 of the ultrasonic inspection device 12 converts the waveform signals input via the switching unit 14 into digital signals and outputs them to the signal processing unit 17.

[0016] The signal processing unit 17 of the ultrasonic inspection device 12 obtains the reception time of the inner surface echo (more specifically, the time when the amplitude of the inner surface echo is maximum) from the waveform signal of each ultrasonic sensor 11 using, for example, a first gate that is preset corresponding to the expected range of the inner surface echo (in other words, the expected reception time and expected amplitude), and calculates the thickness of the pipe 1 based on this and displays it on the display device 13. In this way, changes in the thickness of the pipe 1 at the position of each ultrasonic sensor 11 are monitored.

[0017] However, if the state of the fluid inside the pipe 1 (more specifically, the flow rate and temperature) changes in response to, for example, a load fluctuation in the plant, the temperature of the pipe 1 changes, and the speed of sound in the pipe 1 also changes. This causes a change in the reception time of the inner surface echo even if the thickness of the pipe 1 does not change. This may result in a decrease in the accuracy of measuring the thickness of the pipe 1.

[0018] Therefore, the signal processing unit 17 of the ultrasonic inspection device 12 of this embodiment estimates whether or not an environmental change, such as a change in temperature of the pipe 1, has occurred based on the waveform signals of the multiple ultrasonic sensors 11. If it is estimated that an environmental change has occurred, the signal processing unit 17 does not calculate the thickness of the pipe 1. This calculation control will be explained using FIG. 2.

[0019] 2 is a flowchart showing the procedure of arithmetic control of the ultrasonic inspection device in this embodiment. Note that the control shown in FIG. 2 is assumed to be performed, for example, every time a predetermined time has elapsed.

[0020] In step S1, the pulser 15 of the ultrasonic inspection device 12 sequentially outputs pulse signals to the multiple ultrasonic sensors 11 via the switching unit 14, causing the multiple ultrasonic sensors 11 to sequentially transmit ultrasonic waves. Each ultrasonic sensor 11 receives ultrasonic waves from the piping 1, converts them into waveform signals, and outputs them to the ultrasonic inspection device 12. The receiver 16 of the ultrasonic inspection device 12 sequentially inputs the waveform signals from the multiple ultrasonic sensors 11 via the switching unit 14, converts them into digital signals, and outputs them to the signal processing unit 17. The signal processing unit 17 stores the waveform signals of the multiple ultrasonic sensors 11 in the memory unit 18.

[0021] In step S2, the signal processing unit 17 acquires the reception time of the internal echo from the waveform signal of each ultrasonic sensor 11 and stores it in the storage unit 18. Then, the signal processing unit 17 calculates the change rate of the current internal echo reception time and the previous internal echo reception time (in other words, acquired a predetermined time ago) stored in the storage unit 18.

[0022] In step S3, the signal processing unit 17 first sets the identifier i of the ultrasonic sensor 11 to 1. Then, in step S4, the signal processing unit 17 determines whether the reception time of the inner surface echo in the waveform signal of the first ultrasonic sensor 11 is equal to or less than a preset threshold value t0 (for example, a value set slightly smaller than a normal value when no thinning of the pipe 1 or environmental change occurs).

[0023] If the reception time of the internal echo in the waveform signal of the first ultrasonic sensor 11 is equal to or shorter than the threshold value t0, the process proceeds to step S5. In step S5, the signal processing unit 17 determines whether the reception time of the internal echo in the waveform signal of the second ultrasonic sensor 11 adjacent to the first ultrasonic sensor 11 exceeds the threshold value t0. If the reception time of the internal echo in the waveform signal of the second ultrasonic sensor 11 exceeds the threshold value t0, the process proceeds to step S7.

[0024] 3(a) and 3(b), for example, when the reception time t1 of the inner surface echo E1 in the waveform signal acquired from one ultrasonic sensor 11A of two adjacent ultrasonic sensors 11A, 11B is equal to or less than the threshold value t0, and when the reception time t2 of the inner surface echo E2 in the waveform signal acquired from the other ultrasonic sensor 11B exceeds the threshold value t0, it is assumed that thinning of the pipe 1 has occurred at the position of the ultrasonic sensor 11A. Therefore, the process proceeds to step S7.

[0025] In step S7, the thickness of the pipe 1 at the position of the first ultrasonic sensor 11 is calculated based on the reception time t1 of the inner surface echo E1 in the waveform signal of the first ultrasonic sensor 11. Thereafter, the process proceeds to step S8.

[0026] If the reception time of the internal echo in the waveform signal of the first ultrasonic sensor 11 is equal to or less than the threshold value t0 and the reception time of the internal echo in the waveform signal of the second ultrasonic sensor 11 is equal to or less than the threshold value t0, the process proceeds to step S6. In step S6, the signal processing unit 17 determines whether the rate of change in the reception time of the internal echo in the first ultrasonic sensor 11 is equal to or less than a preset threshold value u0 (for example, a value set smaller than the rate of change in the temperature of the pipe 1), and also determines whether the rate of change in the reception time of the internal echo in the second ultrasonic sensor 11 is equal to or less than the threshold value u0. If the rate of change in the reception time of the internal echo in the waveform signal of the first ultrasonic sensor 11 is equal to or less than the threshold value u0 and the rate of change in the reception time of the internal echo in the second ultrasonic sensor 11 is equal to or less than the threshold value u0, the process proceeds to step S7.

[0027] 4(a) and 4(b), for example, when the reception time t1 of the inner surface echo E1 in the waveform signal acquired from one ultrasonic sensor 11A of two adjacent ultrasonic sensors 11A, 11B is equal to or less than the threshold value t0 and the rate of change thereof is equal to or less than the threshold value u0, and when the reception time t2 of the inner surface echo E2 in the waveform signal acquired from the other ultrasonic sensor 11B is equal to or less than the threshold value t0 and the rate of change thereof is equal to or less than the threshold value u0, it is assumed that thinning of the pipe 1 has occurred at the positions of the ultrasonic sensors 11A, 11B. Therefore, the process proceeds to step S7.

[0028] In step S7, the thickness of the pipe 1 at the position of the first ultrasonic sensor 11 is calculated based on the reception time of the inner surface echo in the waveform signal of the first ultrasonic sensor 11. Thereafter, the process proceeds to step S8.

[0029] In step S6, if the rate of change in the reception time of the inner echo in the waveform signal of the first ultrasonic sensor 11 exceeds the threshold u0 and the rate of change in the reception time of the inner echo in the second ultrasonic sensor 11 also exceeds the threshold u0, the process proceeds to step S8. That is, since it is assumed that an environmental change, such as a change in the temperature of the pipe 1, has occurred, the process proceeds to step S8 without calculating the thickness of the pipe 1 at the position of the first ultrasonic sensor 11. Note that, in step S4, if the reception time of the inner echo in the waveform signal of the first ultrasonic sensor 11 exceeds the threshold t0, the process also proceeds to step S8 without calculating the thickness of the pipe 1 at the position of the first ultrasonic sensor 11.

[0030] In step S8, the signal processing unit 17 determines whether the identifier i of the ultrasonic sensor has reached the total number n of ultrasonic sensors. Initially, this determination is not satisfied, and the process proceeds to step S9. In step S9, the signal processing unit 17 sets the identifier i of the ultrasonic sensor 11 to i = i + 1 = 2. Thereafter, the signal processing unit 17 performs the above-mentioned processing on the reception time of the internal echo in the waveform signal of the second ultrasonic sensor 11 and the reception time of the internal echo in the waveform signal of the first or third ultrasonic sensor 11 adjacent to the second ultrasonic sensor 11. The above-mentioned processing is repeated until the identifier i of the ultrasonic sensor 11 becomes i = n.

[0031] As described above, in this embodiment, it is assumed whether or not an environmental change, such as a change in the temperature of the pipe 1, has occurred based on the waveform signals of the multiple ultrasonic sensors 11. If it is assumed that an environmental change has occurred, the thickness of the pipe 1 is not calculated. Therefore, it is possible to improve the measurement accuracy of the thickness of the pipe 1 without using a sensor that detects environmental changes.

[0032] However, the adhesive 3 may peel off from the outer surface 2 of the pipe 1 due to, for example, deterioration over time or temperature changes in the pipe 1. When the adhesive 3 peels off, many components of the ultrasonic waves transmitted from the ultrasonic sensor 11 do not propagate inside the pipe 1, and these components are multiply reflected by the outer surface 2 of the pipe 1. This reduces the intensity of the inner surface echo, making it difficult to obtain the reception time of the inner surface echo.

[0033] Therefore, the signal processing unit 17 of the ultrasonic inspection device 12 of this embodiment uses, for example, a second gate that is preset corresponding to the expected range of the oscillation echo (more specifically, corresponding to the ultrasonic wave reflected by the outer surface 2 of the pipe 1) to obtain the reverberation time of the oscillation echo (more specifically, the time until the amplitude of the oscillation echo becomes equal to or less than a predetermined value) from the waveform signal of each ultrasonic sensor 11, and estimates whether or not peeling of the adhesive 3 has occurred based on this. If it estimates that peeling of the adhesive 3 has occurred, it outputs a command to notify this to, for example, the display device 13. The display device 13 displays, for example, a message indicating that peeling of the adhesive has occurred.

[0034] However, as described above, if the state of the fluid in the pipe 1 changes in response to, for example, a load fluctuation in the plant, the temperature of the pipe 1 changes, and the speed of sound in the pipe 1 also changes. This causes the reverberation time of the oscillation echo to change even if the adhesive 3 does not peel off. This may result in a decrease in the accuracy of determining whether the adhesive 3 has peeled off.

[0035] Therefore, as described above, the signal processing unit 17 of the ultrasonic inspection device 12 of this embodiment predicts whether or not an environmental change, such as a change in temperature of the pipe 1, has occurred based on the waveform signals of the multiple ultrasonic sensors 11. If it predicts that an environmental change has occurred, the signal processing unit 17 is configured not to output a command to notify that the adhesive has peeled off. This notification control will be explained using FIG. 5.

[0036] Fig. 5 is a flowchart showing the procedure of notification control of the ultrasonic examination device in this embodiment. Note that the notification control shown in Fig. 5 is performed, for example, after the processing of step S1 in Fig. 2, and is performed every time a predetermined time has elapsed.

[0037] In step S10, the signal processing unit 17 acquires the reverberation time of the oscillation echo from the waveform signal of each ultrasonic sensor 11, and stores it in the memory unit 18. Then, the signal processing unit 17 calculates the rate of change of the reverberation time of the current oscillation echo and the reverberation time of the previous oscillation echo (in other words, acquired a predetermined time ago) stored in the memory unit 18.

[0038] In step S11, the signal processing unit 17 first sets the identifier i of the ultrasonic sensor 11 to 1. Then, in step S12, the signal processing unit 17 determines whether the reverberation time of the oscillation echo in the waveform signal of the first ultrasonic sensor 11 is equal to or greater than a preset threshold value w0 (for example, a value set to be slightly larger than a normal value when no peeling of the adhesive 3 or environmental changes occur).

[0039] If the reverberation time of the oscillation echo in the waveform signal of the first ultrasonic sensor 11 is equal to or greater than the threshold w0, the process proceeds to step S13. In step S13, the signal processing unit 17 determines whether the reverberation time of the oscillation echo in the waveform signal of the second ultrasonic sensor 11 adjacent to the first ultrasonic sensor 11 is equal to or greater than the threshold w0. If the reverberation time of the oscillation echo in the waveform signal of the second ultrasonic sensor 11 is less than the threshold w0, the process proceeds to step S15.

[0040] 6(a) and 6(b), for example, when the reverberation time w1 of the oscillation echo F1 in the waveform signal acquired from one ultrasonic sensor 11A of two adjacent ultrasonic sensors 11A, 11B is equal to or greater than the threshold value w0, and when the reverberation time w2 of the oscillation echo F2 in the waveform signal acquired from the other ultrasonic sensor 11B is less than the threshold value w0, it is assumed that peeling of the adhesive 3 has occurred at the position of the ultrasonic sensor 11A. Therefore, the process proceeds to step S15.

[0041] In step S15, a command to notify that peeling of the adhesive has occurred at the position of the first ultrasonic sensor is output to the display device 13. The display device 13 displays a message to the effect that peeling of the adhesive has occurred at the position of the first ultrasonic sensor. Then, the process proceeds to step S16.

[0042] If the reverberation time of the oscillation echo in the waveform signal of the first ultrasonic sensor 11 is equal to or greater than the threshold value w0 and the reverberation time of the oscillation echo in the waveform signal of the second ultrasonic sensor 11 is equal to or greater than the threshold value w0, the process proceeds to step S14. In step S14, the signal processing unit 17 determines whether the rate of change of the reverberation time of the oscillation echo in the first ultrasonic sensor 11 is equal to or less than a preset threshold value v0 (for example, a value set smaller than the rate of change of the temperature of the pipe 1, and v0 = u0 or v0 ≠ u0), and also determines whether the rate of change of the reverberation time of the oscillation echo in the second ultrasonic sensor 11 is equal to or less than the threshold value v0. If the rate of change of the reverberation time of the oscillation echo in the waveform signal of the first ultrasonic sensor 11 is equal to or less than the threshold value v0 and the rate of change of the reverberation time of the oscillation echo in the second ultrasonic sensor 11 is equal to or less than the threshold value v0, the process proceeds to step S15.

[0043] 7(a) and 7(b), for example, when the reverberation time w1 of the oscillation echo F1 in the waveform signal acquired from one ultrasonic sensor 11A of two adjacent ultrasonic sensors 11A, 11B is equal to or greater than the threshold value w0 and the rate of change thereof is equal to or less than the threshold value v0, and when the reverberation time w2 of the oscillation echo F2 in the waveform signal acquired from the other ultrasonic sensor 11B is equal to or greater than the threshold value t0 and the rate of change thereof is equal to or less than the threshold value v0, it is assumed that peeling of the adhesive 3 has occurred at the positions of the ultrasonic sensors 11A, 11B. Therefore, the process proceeds to step S15.

[0044] In step S15, a command to notify that peeling of the adhesive has occurred at the position of the first ultrasonic sensor is output to the display device 13. The display device 13 displays a message to the effect that peeling of the adhesive has occurred at the position of the first ultrasonic sensor. Then, the process proceeds to step S16.

[0045] In step S14, if the rate of change of the reverberation time of the oscillation echo in the waveform signal of the first ultrasonic sensor 11 exceeds the threshold value v0 and the rate of change of the reverberation time of the oscillation echo in the second ultrasonic sensor 11 also exceeds the threshold value v0, the process proceeds to step S16. That is, since it is assumed that an environmental change, such as a change in the temperature of the pipe 1, has occurred, the process proceeds to step S16 without outputting a command to notify that adhesive peeling has occurred at the position of the first ultrasonic sensor 11. Note that, in step S12, if the reverberation time of the oscillation echo in the waveform signal of the first ultrasonic sensor 11 is less than the threshold value w0, the process also proceeds to step S16 without outputting a command to notify that adhesive peeling has occurred at the position of the first ultrasonic sensor 11.

[0046] In step S16, the signal processing unit 17 determines whether the identifier i of the ultrasonic sensor has reached the total number n of ultrasonic sensors. Initially, this determination is not satisfied, and the process proceeds to step S17. In step S17, the signal processing unit 17 sets the identifier i of the ultrasonic sensor 11 to i = i + 1 = 2. Thereafter, the signal processing unit 17 performs the above-mentioned processing on the reverberation time of the oscillation echo in the waveform signal of the second ultrasonic sensor 11 and the reverberation time of the oscillation echo in the waveform signal of the first or third ultrasonic sensor 11 adjacent to the second ultrasonic sensor 11. The above-mentioned processing is repeated until the identifier i of the ultrasonic sensor 11 becomes i = n.

[0047] As described above, in this embodiment, it is assumed whether an environmental change, such as a change in the temperature of the pipe 1, has occurred based on the waveform signals of the multiple ultrasonic sensors 11. If it is assumed that an environmental change has occurred, a command to notify that the adhesive has peeled off is not output. Therefore, it is possible to improve the accuracy of determining whether the adhesive 3 has peeled off, without using a sensor that detects environmental changes. [Explanation of symbols]

[0048] 1 Piping 2 External surface 3. Adhesive 4. Inner Surface 11, 11A, 11B Ultrasonic sensors 12 Ultrasound inspection equipment

Claims

1. a plurality of ultrasonic sensors fixed to an outer surface of the pipe with an adhesive; an ultrasonic inspection device that transmits ultrasonic waves from the plurality of ultrasonic sensors toward an inner surface of the pipe, and acquires a plurality of waveform signals that are obtained by receiving and converting the ultrasonic waves from the pipe by the plurality of ultrasonic sensors, The ultrasonic inspection device includes: When a reception time of an inner surface echo in one waveform signal acquired from one of two adjacent ultrasonic sensors is equal to or less than a predetermined first threshold value, and when a reception time of an inner surface echo in the other waveform signal acquired from the other ultrasonic sensor exceeds the first threshold value, the thickness of the pipe at the position of the one ultrasonic sensor is calculated based on the reception time of the inner surface echo in the one waveform signal, When the reception time of the inner surface echo in the one waveform signal is equal to or less than the first threshold value and the rate of change thereof is equal to or less than a predetermined second threshold value, and when the reception time of the inner surface echo in the other waveform signal is equal to or less than the first threshold value and the rate of change thereof is equal to or less than the second threshold value, a thickness of the pipe at the position of the one ultrasonic sensor is calculated based on the reception time of the inner surface echo in the one waveform signal, a pipe inspection device that does not calculate the thickness of the pipe at the position of one of the ultrasonic sensors when, in one of the waveform signals, the reception time of the inner surface echo is equal to or less than the first threshold value and the rate of change thereof exceeds the second threshold value, and when, in the other waveform signal, the reception time of the inner surface echo is equal to or less than the first threshold value and the rate of change thereof exceeds the second threshold value.

2. The piping inspection device according to claim 1, The ultrasonic inspection device includes: outputting a command to notify that peeling of the adhesive has occurred at the position of the one ultrasonic sensor when the reverberation time of the oscillation echo in the one waveform signal is equal to or greater than a preset third threshold value and the reverberation time of the oscillation echo in the other waveform signal is less than the third threshold value; outputting a command to notify that peeling of the adhesive has occurred at the position of the one ultrasonic sensor when the reverberation time of the oscillator echo is equal to or greater than the third threshold value and the rate of change thereof is equal to or less than a predetermined fourth threshold value in the one waveform signal, and when the reverberation time of the oscillator echo is equal to or greater than the third threshold value and the rate of change thereof is equal to or less than the fourth threshold value in the other waveform signal; a piping inspection device that does not output a command to notify that peeling of the adhesive has occurred at the position of one of the ultrasonic sensors when, in one waveform signal, the reverberation time of the oscillator echo is equal to or greater than the third threshold value and the rate of change thereof exceeds the fourth threshold value, and when, in the other waveform signal, the reverberation time of the oscillator echo is equal to or greater than the third threshold value and the rate of change thereof exceeds the fourth threshold value.

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