Lining product nondestructive inspection method and hybrid inspection method

Abstract

[Problem] To provide a nondestructive inspection method for a lining product, the method being capable of detecting abnormalities such as rising or peeling of a resin liner or deterioration of an adhesive agent and detecting a weld line and a vent line of the resin liner, by inspecting the internal state of the lining product from the outside. [Solution] According to this nondestructive inspection method for inspecting the internal state of a lining product from the outside, an input signal is transmitted to the lining product being an object to be measured, a response signal from the object is received, and an abnormal part of the object is detected on the basis of the response signal.

Description

Non-destructive inspection method and hybrid inspection method for lining products

[0001] The present invention relates to a non-destructive inspection method for non-destructively inspecting the internal state of a lining product from the outside, and more specifically, by using active sensing technology, for example, detecting floating or peeling of a resin liner applied inside a lining tank or a lining pipe, or detecting a weld line of the resin liner. The present invention relates to a non-destructive inspection method and a hybrid inspection method capable of doing so.

[0002] Conventionally, lining products such as lining tanks and lining pipes in which a resin liner (lining layer) is attached to the inner wall portion of a metal tank body or a metal pipe body are known. For such a resin liner of a lining product, for example, a highly chemical-resistant one such as a polytetrafluoroethylene (PTFE) sheet is used. Such lining products are used, for example, for storing and feeding chemical liquids such as acid solutions and alkali solutions used during semiconductor manufacturing.

[0003] Such lining products may experience aging deterioration due to repeated use. As one of the mechanisms of deterioration, chemical liquids that have permeated through the resin liner (lining layer) attached to the inner wall portion of the metal tank body or pipe body via an adhesive corrode the adhesive, the metal tank body, or the pipe body. Then, as the permeated chemical liquid vaporizes, the chemical liquid gas accumulates in the adhesive layer, causing the resin liner to lift off from the metal tank body or pipe body. Furthermore, a liquid pool is formed by the chemical liquid that has permeated to the location where this "lifting" has occurred, breaking the weld line of the resin liner, and accelerating the corrosion of the metal tank body or pipe body by the chemical liquid. In this way, as the corrosion of the metal tank body or pipe body progresses, the resin liner will also peel off.

[0004] The floating or peeling of the resin liner may affect the purity of the chemical liquid inside the lining product, and in some cases, the lining product may become unusable. Therefore, the lining product requires regular inspections to check for abnormalities such as floating or peeling of the resin liner.

[0005] Japanese Patent Publication No. 2009-133845 Japanese Patent Publication No. 2009-133767

[0006] Non-destructive testing methods for lining products include, for example, thermal imaging using thermography (Patent Document 1), ultrasonic flaw testing, and insulation resistance measurement (Patent Document 2).

[0007] However, these non-destructive testing methods had drawbacks, such as low measurement accuracy and high labor costs. Furthermore, in lined products, the connections between resin liners are made by resin welding, but these weld lines are prone to becoming the starting point of damage due to the effects of chemicals and internal pressure. If deterioration occurs at the weld line, such as lifting, it can lead to serious damage such as chemical leakage or chemical contamination of the tank body, so replacement with a new tank is recommended. For this reason, it is important to understand the weld lines in lined products, but in the case of older lined products, product drawings that show the weld lines may not exist. In addition, the thermal imaging diagnostics, ultrasonic flaw testing, and insulation resistance measurement mentioned above were unable to detect the weld lines.

[0008] Furthermore, lined tanks have vent lines between the metal tank body and the resin liner. These vent lines connect vent holes and allow gases generated inside the lined tank to pass through and be released to the outside, preventing abnormal pressure buildup inside the tank. However, if acids or other substances enter these vent lines, rust is more likely to form on the tank body. Therefore, understanding the vent lines in lined tanks is also important.

[0009] In view of the current situation, the present invention aims to provide a non-destructive testing method and a hybrid testing method for lined products that can inspect the internal condition of lined products from the outside to detect abnormalities such as lifting or peeling of the resin liner, deterioration of the adhesive, rust on the metal tank body or metal pipe body, and to detect weld lines and vent lines of the resin liner.

[0010] The present invention was made to solve the problems of the prior art described above, and the non-destructive testing method and hybrid testing method for lining products of the present invention include those configured as follows.

[0011] [1] A non-destructive testing method for inspecting the internal condition of a lining product from the outside, comprising transmitting an input signal to the lining product which is the object to be measured, receiving a response signal from the object to be measured, and detecting an abnormal part of the object to be measured based on the response signal.

[0012] [2] The non-destructive testing method according to [1], wherein the abnormal part of the object to be measured is detected using the waveform changes of the response spectrum based on the response signal obtained in the normal part of the object to be measured and the response spectrum based on the response signal obtained in the abnormal part of the object to be measured.

[0013] [3] The non-destructive testing method according to [1] or [2], wherein the input signal is a sweep wave including a frequency in the range of 500 Hz to 10 MHz.

[0014] [4] The non-destructive testing method according to any one of [1] to [3], wherein the internal condition of the lining product is at least one of the following: lifting of the resin liner, delamination of the resin liner, weld lines between resin liners, vent lines, deterioration of the adhesive, rust on the metal tank body or metal piping body.

[0015] [5] A hybrid inspection method for inspecting the internal condition of a lining product from the outside, comprising detecting a weld line between resin liners using the non-destructive testing method described in any of [1] to [4] in the circumferential direction of the object to be measured, and detecting at least one of lifting of the resin liner or delamination of the resin liner near the detected weld line using thermal imaging diagnosis by active thermography.

[0016] According to the present invention, by inputting a sweep wave within a predetermined range to the lining product to be measured and acquiring its response spectrum, the internal state of the lining product, i.e., deterioration such as lifting or peeling of the resin liner, deterioration of the adhesive, rust on the metal tank body or metal pipe body, and weld lines of the resin liner can be detected non-destructively.

[0017] Figure 1 is a schematic diagram illustrating the configuration of a non-destructive testing apparatus used to carry out one embodiment of the non-destructive testing method for lining products of the present invention. Figure 2(a) is a schematic diagram of the front side of the model test piece to be measured, and Figure 2(b) is a schematic diagram of the back side of the model test piece to be measured. Figure 3(a) is a graph showing the response spectrum of the measurement point in the normal part of the model test piece, and Figure 3(b) is a graph showing the response spectrum of the measurement point in the floating part of the model test piece. Figure 4 is a mapping of the detected value D calculated based on the intensity of the response signal at 2.5 kHz to 2.8 kHz and 4.6 kHz to 4.9 kHz. Figure 5 is a graph showing a part of the response spectrum when the deterioration state of the adhesive was measured using the non-destructive testing apparatus shown in Figure 1. Figure 6 is a graph showing a part of the response spectrum when the presence or absence of rust was measured using the non-destructive testing apparatus shown in Figure 1. Figure 7 is a mapping of the detected value D when a lining tank was measured as the target of measurement. Figure 8 shows a mapping of the detected value D when a lined tank was measured as another example. Figure 9 shows a mapping of the detected value D when a lined tank was measured as another example. Figure 10 shows a mapping of the detected value D when a lined tank was measured as another example. Figure 11 is a graph showing the results of measurements performed using conventional ultrasonic testing. Figure 12 shows a mapping of the detected value D when a lined tank was measured as another example. Figure 13 shows the measurement results when a lined tank was measured using a hybrid inspection method.

[0018] The embodiments (examples) of the present invention will be described in more detail below with reference to the drawings. Figure 1 is a schematic diagram illustrating the configuration of a non-destructive testing apparatus used to carry out one embodiment of the non-destructive testing method for lined products of the present invention.

[0019] As shown in Figure 1, the non-destructive testing apparatus 10 of this embodiment includes a transmitting means 12 for transmitting a predetermined input signal and a receiving means 18 for receiving a response signal.

[0020] The transmitting means 12 includes a transmitting terminal 14 that transmits a predetermined input signal to the measurement target 30 while in contact with the measurement target 30, and a signal generating means 16 that generates the input signal to be transmitted and transmits it to the transmitting terminal 14.

[0021] The receiving means 18 includes a receiving terminal 20 that receives a response signal from the object to be measured 30 while in contact with the object to be measured 30, and a detection means 22 that records the received response signal and calculates a response spectrum.

[0022] Furthermore, known sensors such as AE (acoustic emission) sensors, ultrasonic sensors, and acceleration sensors can be used as the transmitting means 12 and receiving means 18.

[0023] The non-destructive testing method of this embodiment can be carried out using the non-destructive testing apparatus 10 configured as described above, following the procedure below. In this embodiment, a model test piece 40 is used as the object to be measured 30 for explanation, but lined products such as lined tanks and lined pipes can also be inspected in the same manner.

[0024] As shown in Figure 2, the model test piece 40 consists of a stainless steel plate (metal plate 42) to which two polytetrafluoroethylene (PTFE) resin liners 44 and 46 are bonded using adhesive. The connection between resin liner 44 and resin liner 46 is made by resin welding, forming a weld line 48. In addition, a pseudo-raised area 49 is formed approximately in the center of resin liner 44. Reference numerals 48' and 49' in Figure 2(b) indicate the parts corresponding to the weld line 48 and raised area 49 shown in Figure 2(a).

[0025] With the non-destructive testing device 10 in contact with the measurement point T on the metal plate 42 side of the measurement target 30 (model test piece 40), the signal generating means 16 generates an input signal and transmits it from the signal generating terminal 14, while the receiving terminal 20 receives a response signal from the model test piece 40, and the detection means 22 records the response signal.

[0026] The input signal may be a sine wave of a predetermined frequency or a sweep wave. Here, a sweep wave is a signal whose frequency changes within a predetermined range over time. In this embodiment, the predetermined frequency range for input as a sweep wave can be, for example, 500 Hz to 10 MHz, preferably 600 Hz to 5 MHz, and more preferably 1 kHz to 1 MHz. If the frequency is outside this range, the measurement results are more susceptible to noise due to the influence of the external environment, and it becomes difficult to detect abnormal parts in the first place. As will be described later, the frequency band in which the difference in waveform between normal and abnormal parts becomes significant varies depending on the shape, size, and material of the object to be measured 30. Therefore, it is preferable to appropriately adjust the frequency range for input as a sweep wave depending on the shape, size, and material of the object to be measured 30.

[0027] Furthermore, in this embodiment, the non-destructive testing device 10 is sequentially brought into contact with multiple measurement points T to perform measurements. However, multiple non-destructive testing devices 10 may be brought into contact with multiple measurement points T to perform measurements simultaneously.

[0028] Furthermore, the non-destructive testing device 10 can be configured to automatically measure each measurement point T by mounting it on a robot equipped with, for example, a means of movement and a means of position recognition.

[0029] The detection means 22 calculates a response spectrum from the recorded response signal. Figure 3 is a graph showing an example of a response spectrum; Figure 3(a) is a graph showing the response spectrum at measurement point T1 in the normal part of the model test piece 40, and Figure 3(b) is a graph showing the response spectrum at measurement point T2 in the floating part 49 of the model test piece 40.

[0030] As shown in Figure 3, there are differences in the waveform between the response spectrum in the normal area and the response spectrum in the abnormal area (floating) in certain frequency bands. By utilizing these waveform differences, it is possible to detect floating or peeling of the resin liner, deterioration of the adhesive, rust on the metal tank body or metal piping body, weld lines on the resin liner, vent lines, etc.

[0031] In the example shown in Figure 3, the differences are significant in the 2.5 kHz–2.8 kHz and 4.6 kHz–4.9 kHz ranges. Therefore, abnormal areas are detected based on the intensity of the response signal in the 2.5 kHz–2.8 kHz and 4.6 kHz–4.9 kHz ranges.

[0032] Figure 4 maps the detected values ​​D calculated based on the intensity of the response signal at 2.5 kHz to 2.8 kHz and 4.6 kHz to 4.9 kHz. While there are no particular limitations on the method for calculating the detected values ​​D, it is preferable to calculate them in a way that clearly shows the difference in the intensity of the response signal.

[0033] As shown in Figure 4, the detected value D at the positions corresponding to the weld lines 48 and bulges 49 of the model test piece 40 is high, indicating that the weld lines 48 and bulges 49 of the model test piece 40 can be detected.

[0034] In this embodiment, abnormalities are detected using the intensity of the response signal in the ranges of 2.5 kHz to 2.8 kHz and 4.6 kHz to 4.9 kHz. However, the frequency bands in which the difference in waveform between normal and abnormal areas becomes significant will vary depending on the shape, size, and material of the object being measured 30.

[0035] Furthermore, in this embodiment, there are two frequency bands where the difference in the waveform of the response spectrum is significant, and the detected value D is calculated based on these. However, if, for example, there is only one frequency band where the difference in waveform is significant, the detected value D may be calculated based on the sum of the intensities of the response signals in that frequency band. In other words, the detected value D can be calculated from the intensity of the response signal in such a way that the difference between the detected value D in the normal section and the detected value D in the abnormal section is large.

[0036] Figure 5 is a graph showing a portion of the response spectrum when the deterioration state of the adhesive was measured using the non-destructive testing apparatus 10 shown in Figure 1. Figure 5(a) is the response spectrum for the measurement target 30 coated only with adhesive, Figure 5(b) is the response spectrum for the measurement target 30 after the adhesive has been immersed in hydrochloric acid for one week, and Figure 5(c) is the response spectrum for the measurement target 30 after the adhesive has been immersed in hydrochloric acid for three weeks.

[0037] As shown in Figure 5, the vibration pattern of the response spectrum changes as time passes after immersion in hydrochloric acid, that is, as the adhesive deteriorates due to the hydrochloric acid. Specifically, as shown in Figure 5, the dip that occurred around 312 kHz changes to appear separately on the low-frequency and high-frequency sides as the deterioration due to hydrochloric acid progresses.

[0038] In other words, by detecting changes in the vibration pattern of such response spectra, the degradation state of adhesives and other materials due to chemical solutions can be measured non-destructively.

[0039] Figure 6 is a graph showing a portion of the response spectrum when measuring the presence or absence of rust using the non-destructive testing device 10 shown in Figure 1. Figure 6(a) shows the response spectrum when a steel plate is the object of measurement 30, and Figure 6(b) shows the response spectrum when rust has occurred on the back surface of a steel plate that is the object of measurement 30.

[0040] As shown in Figure 6, in the measurement target 30 where rust has occurred, peaks appear in different frequency bands (around 35 kHz and around 80 kHz) than in the measurement target 30 where rust has not occurred, and the spectrum is distorted around 50 kHz to 70 kHz, thus allowing for the determination of whether or not rust is present.

[0041] <Example 1> Figure 7 shows a mapping of the detected value D when a lining tank was measured as the measurement target 30. In Example 1, the measurement target 30 is a lining tank in which a polytetrafluoroethylene (PTFE) resin liner is bonded to the inner wall of a stainless steel tank body via an adhesive.

[0042] Even when measuring such a lined tank, as shown in Fig. 7(a), the floating of the resin liner can be detected, and as shown in Fig. 7(b), the weld line of the resin liner can also be detected.

[0043] <Example 2> Fig. 8 shows the detected value D mapped when measuring the lined tank as the measurement target 30. In Example 2, a lined tank having the same configuration as in Example 1 and having been painted on the outer wall side of the tank body is used as the measurement target 30.

[0044] Even when measuring such a lined tank, as shown in Fig. 8(a), the floating of the resin liner can be detected, and as shown in Fig. 8(b), the weld line of the resin liner can also be detected.

[0045] <Example 3> Fig. 9 shows the detected value D mapped when measuring the lined tank as the measurement target 30. In Example 3, a lined tank having the same configuration as in Example 1 and filled with water is used as the measurement target 30.

[0046] Even when measuring such a lined tank, as shown in Fig. 9(a), the floating of the resin liner can be detected, and as shown in Fig. 9(b), the weld line of the resin liner can also be detected.

[0047] <Example 4> Fig. 10 shows the detected value D mapped when measuring the lined tank as the measurement target 30. In Example 4, a lined tank having the same configuration as in Example 1, having been painted on the outer wall side of the tank body, and filled with water inside the lined tank is used as the measurement target 30.

[0048] Even when measuring such a lined tank, as shown in Fig. 10(a), the floating of the resin liner can be detected, and as shown in Fig. 10(b), the weld line of the resin liner can also be detected.

[0049] <Comparative Example> Figure 11 is a graph showing the results of measurements performed using conventional ultrasonic testing. In this comparative example, the model test piece 40 shown in Figure 2 was used as the measurement target 30. The ultrasonic generator used was a "Krautkramer USM 100" manufactured by Waygate Technologies, and the probe used was a "Standard Vertical Probe 5C20N" manufactured by Inspection Technology Research Institute Co., Ltd. The measurement conditions were an input signal center frequency of 5 MHz, a pulse voltage of 100 V, a gain of 22 dB, and a sound velocity of 5790 m / s in the test piece 40.

[0050] As shown in Figure 11, while it is possible to detect the lifting of the resin liner by confirming the difference from the healthy part, it is difficult to detect the weld line of the resin liner because the difference from the healthy part is extremely small.

[0051] <Example 5> Figure 12 shows a mapping of the detected value D when a lining tank was measured as the measurement target 30. In Example 5, the measurement target 30 is a lining tank in which a polytetrafluoroethylene (PTFE) resin liner is bonded to the inner wall of a stainless steel tank body via an adhesive and a vent line containing the adhesive.

[0052] When measuring such a lined tank, a vent line (at Y = 600 mm) can be detected, as shown in Figure 12.

[0053] <Example 6> Figure 13(a) shows a mapping of the detected value D when the lining tank was measured as the measurement target 30, and Figure 13(b) is a thermal image of the measurement target 30 obtained using active thermography.

[0054] Here, active thermography is a method that detects whether or not there is an abnormality in the object to be measured 30 by detecting the temperature change of the surface caused by applying heat to the object to be measured 30 using an infrared camera or infrared sensor.

[0055] In this embodiment, first, the weld lines on the measurement target 30 are detected by mapping the detected value D using the non-destructive testing device 10 shown in Figure 1, as shown in Figure 13(a).

[0056] At this time, due to the manufacturing dimensions of the resin liner that is bonded to the inner wall of the lining tank, which is the object of measurement 30, weld lines are always present at regular intervals in the circumferential direction of the lining tank. For this reason, the non-destructive testing device 10 measures the object of measurement 30 for one full rotation in the circumferential direction. As a result, as shown in Figure 13(a), the locations where weld lines exist in the circumferential direction of the object of measurement 30 can be detected. In Figure 13(a), three weld lines (corresponding to L1, L2, and L3) can be identified.

[0057] Next, thermal imaging is performed on the vicinity of the detected weld line using active thermography. At this time, the vicinity of the weld line depends on the shape and size of the lining tank, which is the object of measurement 30, but for example, it can be several tens of centimeters in front of and behind the weld line in the circumferential direction.

[0058] By performing thermal imaging diagnostics in this manner, abnormalities such as lifting or delamination of the resin liner near the weld line can be detected, as shown in Figure 13(b). In Figure 13(b), lifting of the resin liner (symbol S) can be confirmed.

[0059] Generally, thermal imaging diagnosis using active thermography is faster than diagnosis using the non-destructive testing device 10 of the present invention. However, as described above, while thermal imaging diagnosis using thermography can detect lifting and delamination of the resin liner, it cannot detect the weld lines of the resin liner.

[0060] Therefore, by using a hybrid inspection method that combines diagnosis using the non-destructive testing device 10 of the present invention, which can detect the weld line of the resin liner, with thermal imaging diagnosis using active thermography, which has a high diagnostic speed, it is possible to quickly diagnose abnormalities near the weld line, which are prone to leading to serious damage.

[0061] Table 1 shows the measurement area ratio and measurement time for a lining tank when the entire surface is measured using the non-destructive testing device 10 of the present invention (full surface measurement), when welding lines are detected in the circumferential direction using the non-destructive testing device 10 of the present invention and the area near the welding lines is measured using the non-destructive testing device 10 of the present invention (partial measurement), and when welding lines are detected in the circumferential direction using the non-destructive testing device 10 of the present invention and thermal image diagnosis is performed near the welding lines using active thermography (hybrid measurement).

[0062]

[0063] Here, the measurement area ratio is shown with the measurement area when the entire surface is measured as 100%. Also, the lining tank, which is the object of measurement 30, is 1 m ３ A tank with the following capacity is used.

[0064] As shown in Table 1, by performing hybrid measurement, abnormalities near the weld line can be detected in about 1 / 2 to 1 / 3 of the measurement time compared to when performing full-surface measurement using the non-destructive testing device 10 of the present invention.

[0065] Furthermore, although this embodiment describes an example where a lining tank is used as the measurement target 30, hybrid measurement can also be performed on other lining products by determining the circumferential direction as the direction in which weld lines can be periodically detected based on the bonding direction of the resin liner.

[0066] Furthermore, in this embodiment, a hybrid measurement is performed that combines measurement using the non-destructive testing device 10 of the present invention with thermal image diagnosis using active thermography, due to the significant effect of shortening the measurement time. However, the invention is not limited to this, and a hybrid measurement can also be performed that combines measurement using the non-destructive testing device 10 of the present invention with diagnostic methods such as thermal image diagnosis using passive thermography, eddy current measurement, or ultrasonic flaw detection.

[0067] Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications are possible without departing from the object of the present invention.

[0068] 10 Non-destructive testing device 12 Transmitting means 14 Transmitting terminal 16 Signal generating means 18 Receiving means 20 Receiving terminal 22 Detection means 30 Object to be measured 40 Model test piece 42 Metal plate 44 Resin liner 46 Resin liner 48 Weld line 49 Delamination L1 Weld line L2 Weld line L3 Weld line S Delamination

Claims

1. A non-destructive testing method for inspecting the internal condition of a lining product from the outside, comprising transmitting an input signal to the lining product to be measured, receiving a response signal from the product to be measured, and detecting an abnormal part of the product to be measured based on the response signal.

2. The non-destructive testing method according to claim 1, wherein the abnormal part of the object to be measured is detected using the waveform changes of the response spectrum based on the response signal obtained in the normal part of the object to be measured and the response spectrum based on the response signal obtained in the abnormal part of the object to be measured.

3. The non-destructive testing method according to claim 1, wherein the input signal is a sweep wave including a frequency in the range of 500 Hz to 10 MHz.

4. The non-destructive testing method according to claim 1, wherein the internal condition of the lining product is at least one of the following: lifting of the resin liner, delamination of the resin liner, weld lines between resin liners, vent lines, deterioration of the adhesive, rust on the metal tank body or metal piping body.

5. A hybrid inspection method for inspecting the internal condition of a lining product from the outside, comprising: detecting welding lines between resin liners in the circumferential direction of the object to be measured using the non-destructive testing method described in any one of claims 1 to 4; and detecting at least one of lifting of the resin liner or delamination of the resin liner near the detected welding lines using thermal imaging diagnostics by active thermography.

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