Method and device for estimating deterioration of piping components

Abstract

To provide a non-destructive inspection method which allows for easily and inexpensively estimating deterioration of synthetic resin piping members.SOLUTION: A deterioration estimation method provided herein uses a measurement device comprising a striking hammer 13 and an acceleration sensor 17 attached to the striking hammer 13 and comprises striking a surface of a synthetic resin piping member P using the striking hammer 13, temporally measuring acceleration of the striking hammer 13 using the acceleration sensor 17, and estimating whether a physical property retention rate of the piping member P has decreased to less than a predetermined value or not on the basis of the measured acceleration of the striking hammer 13 to estimate deterioration of the piping member P.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a piping member deterioration estimation method and a piping member deterioration estimation device for estimating deterioration of a piping member made of synthetic resin. [Background technology]

[0002] As a non-destructive inspection method for piping components of a piping system, various methods according to purpose have been known so far, such as visual inspection (visual inspection, visual method) and percussion inspection (percussion inspection, percussion method). Visual inspection is a method to visually check the surface condition and defects of piping components, such as cracks, peeling, and connection failures. Changes such as discoloration that appear on the surface of piping components may indicate abnormalities during use, and phenomena that occur on the surface of piping components can be detected with high sensitivity. However, visual inspection only observes changes on the surface of piping components, and cannot observe internal defects of piping components in a non-destructive manner. Percussion inspection is a method in which an operator strikes the object to be inspected with a hammer, and judges the presence or absence of defects such as deterioration or reduction in wall thickness (i.e. thinning) based on the striking sound and vibration at that time. However, in addition to the operator needing experience to make a judgment, the judgment depends on the operator's sense, making it difficult to quantify and lacking objectivity.

[0003] In order to solve the above problems, ultrasonic flaw detection tests, radiographic tests, and the like have been conventionally used as non-destructive testing methods for inspecting defects in piping components. These methods aim to find the presence, location, and approximate size of defects inside piping components. In addition, as for impact investigations, as described in Patent Documents 1, 2, and 3, there have been proposed inspection devices, diagnostic devices, and diagnostic methods that measure the results of impacts with a hammer and quantify them as objective data. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 7-280779 [Patent Document 2] JP 2002-257700 A [Patent Document 3] JP 2000-131292 A Summary of the Invention [Problem to be solved by the invention]

[0005] The ultrasonic testing and radiography testing described above are not problematic when the location of deterioration is known in advance. However, when inspecting an entire piping system, ultrasonic testing not only requires a long inspection time, but also requires a large inspection cost. Furthermore, radiography testing has the problem that the inspection equipment is expensive, there is a risk of radiation, and it is difficult to inspect for long periods of time.

[0006] In addition, in the impact investigation, Patent Document 1, which discloses a non-destructive inspection device, specifies only the exterior wall of a building as the object to be inspected, and Patent Document 2 relates to a wood deterioration diagnostic device and a wood deterioration diagnostic method. Furthermore, Patent Document 3 discloses a piping inspection device that inspects the corrosion state of piping that uses metal pipes. Thus, none of Patent Documents 1 to 3 discloses the inspection of defects in synthetic resin piping.

[0007] SUMMARY OF THE PRESENT EMBODIMENTS Accordingly, an object of the present invention is to provide a non-destructive inspection method capable of easily and inexpensively estimating the deterioration of synthetic resin piping components in order to solve the problems present in the prior art. [Means for solving the problem]

[0008] In view of the above object, the present invention provides, as a first aspect, a method for estimating deterioration of a piping component, which uses a measuring device including an impact hammer and an acceleration sensor attached to the impact hammer to estimate a decrease in a property retention rate of a synthetic resin piping component, the method comprising: striking a surface of the synthetic resin piping component with the impact hammer; measuring the acceleration of the impact hammer over time with the acceleration sensor; and and an index I calculated from the equation I=Va / Vr using the impact velocity Va when the impact hammer collides with the surface of the piping component and the rebound velocity Vr when the impact hammer rebounds from the surface of the piping component, and then, based on at least one of the mechanical impedance ZR and the index I thus calculated, Estimating whether the property retention rate of the piping member is lower than a predetermined value The impact velocity Va is calculated by integrating the measured acceleration over time from 0 to a maximum value, the rebound velocity Vr is calculated by integrating the measured acceleration over time from the maximum value to a ... max When the mass of the striking hammer and the measured acceleration of the striking hammer are used, F max is calculated, and the mechanical impedance ZR is expressed by the formula ZR=F max / Vr, and threshold values ​​are respectively set in advance for the mechanical impedance ZR and the index I, and when at least one of the mechanical impedance ZR and the index I obtained by measurement falls below the respective predetermined threshold values ​​for the mechanical impedance ZR and the index I, it is estimated that the property retention rate of the piping member has decreased below a predetermined value. A method for estimating deterioration of a piping component is provided.

[0009] In the above-mentioned deterioration estimation method for a piping member, a striking hammer equipped with an acceleration sensor is used to strike the surface of a synthetic resin piping member, thereby estimating whether the property retention rate of the piping member has decreased below a predetermined value. The striking of the surface of the piping member by the striking hammer is roughly divided into a penetration process in which the striking hammer strikes the surface of the piping member and the piping member is deformed by the force of the striking hammer, and a rebound process in which the deformation of the piping member reaches a maximum and the striking hammer is pushed out in the opposite direction to the striking direction by the rebound force from the piping member accompanying the restoration from the deformation, and is separated from the surface of the piping member. The present inventor has found that the property retention rate of the piping member affects the acceleration of the striking hammer when the piping member is restored from the deformation after being struck by the striking hammer, i.e., in the rebound process. Using this knowledge, the above-mentioned deterioration estimation method for a piping member estimates the decrease in the property retention rate of the piping member, i.e., the deterioration of the piping member, based on the acceleration of the striking hammer. Here, the physical property retention rate of a piping component means the ratio of the measured value of the evaluation physical property of the piping component being measured to the value of the evaluation physical property of a reference synthetic resin piping component (for example, the evaluation physical property value of an unused synthetic resin piping component or a standard value), and examples of the evaluation physical properties include tensile elongation (tensile elongation at break, tensile elongation at fracture), tensile strength, impact strength (Charpy impact strength, falling weight impact strength), and flattening.

[0011] The impact velocity Va is calculated by integrating the acceleration of the impact hammer during the penetration process from 0 to the maximum value, and the rebound acceleration Vr is calculated by integrating the acceleration of the impact hammer during the rebound process from the maximum value to 0. The maximum impact force F generated when the impact hammer collides with the surface of the piping component is calculated by integrating the acceleration of the impact hammer during the rebound process from the maximum value to 0. max is the mass m of the striking hammer and the maximum acceleration a max It is calculated as the product of ZR and F. max If the value obtained by / Vr is the mechanical impedance ZR in the rebound process, and the ratio of the impact speed Va to the rebound speed Vr is the index I, then both the mechanical impedance ZR and the index I include the rebound speed Vr, and the decrease in the property retention rate of the piping component should be reflected in the mechanical impedance ZR and the index I. From this prediction, the inventor has found that a deteriorated piping component whose property retention rate falls below a predetermined value can be estimated based on the mechanical impedance ZR in the rebound process and the index I. Using this knowledge, the above-mentioned method for estimating deterioration of a piping component estimates whether or not the property retention rate of the piping component falls below a predetermined value, i.e., whether or not the piping component is deteriorated, based on at least one of the mechanical impedance ZR in the rebound process and the index I.

[0013] before When both the mechanical impedance ZR and the index I obtained by measurement are lower than their respective predetermined threshold values, it may be estimated that there is a higher probability that the property retention rate of the piping component has decreased below a predetermined value.

[0014] It is also preferable that thresholds are predefined for the mechanical impedance ZR and the index I for each nominal diameter and material of the synthetic resin piping member, and that the predefined thresholds for the mechanical impedance ZR and the index I corresponding to the nominal diameter and material of the piping member to be measured are compared with the mechanical impedance ZR and the index I determined by measurement to estimate whether the property retention rate of the piping member has decreased below a predefined value. By predefining thresholds for the mechanical impedance ZR and the index I for each nominal diameter and material of the piping member, the accuracy of estimating the decrease in the property retention rate of the piping member can be further improved.

[0015] Furthermore, it is preferable to obtain a correlation between temperature and the mechanical impedance ZR and the index I for each nominal diameter and material, temperature-compensate the mechanical impedance ZR and the index I obtained by measurement based on the correlation obtained in advance, the nominal diameter and material of the piping member, and the temperature at the time of measurement, and estimate whether the property retention rate of the piping member has decreased below a predetermined value based on at least one of the temperature-compensated mechanical impedance ZR' and index I'. By considering the effect of the temperature at the time of measurement, the accuracy of estimating the decrease in the property retention rate of the piping member can be further improved.

[0016] In addition, as a second aspect, the present invention provides a piping component deterioration estimation device for estimating a decrease in a property retention rate of a synthetic resin piping component, the device including: an impact hammer for striking a surface of the synthetic resin piping component; an acceleration sensor attached to the impact hammer; a measurement value storage unit for storing, over time, an acceleration of the impact hammer measured by the acceleration sensor; and a deterioration estimation unit for estimating whether or not the property retention rate of the piping component has decreased below a predetermined value based on the acceleration stored in the measurement value storage unit. a threshold value storage unit that stores predetermined threshold values ​​for the mechanical impedance ZR and the index I for each nominal diameter and material of the piping member; Equipped with The deterioration estimation unit obtains, from the acceleration stored in the measurement value storage unit, at least one of a mechanical impedance ZR during the rebound process in which the impact hammer rebounds from the surface of the piping component in the direction opposite to the direction in which the impact hammer impacts the surface of the piping component, and an index I calculated by the equation I=Va / Vr from the impact velocity Va when the impact hammer impacts the surface of the piping component and the rebound velocity Vr when the impact hammer rebounds from the surface of the piping component, and determines whether the mechanical impedance ZR and index I are lower than respective predetermined threshold values ​​corresponding to the nominal diameter and material of the piping component to be measured, When both the mechanical impedance ZR and the index I obtained by measurement are lower than the predetermined value, it is estimated that there is a high probability that the physical property retention rate of the piping component is lower than a predetermined value, the collision speed Va is calculated by time integrating the acceleration stored in the measurement value storage unit over the time it takes for the acceleration to increase from 0 to a maximum value, the rebound speed Vr is calculated by time integrating the acceleration stored in the measurement value storage unit over the time it takes for the acceleration to decrease from the maximum value to 0 again, and the maximum value of the impact force generated when the impact hammer collides with the surface of the piping component is calculated as F. max When the mass of the impact hammer and the acceleration of the impact hammer stored in the measurement value storage unit are used, F max is calculated, and the mechanical impedance ZR is calculated according to the formula ZR=F max / Vr A piping component deterioration estimation device is provided.

[0017] As with the above-mentioned piping component deterioration estimation method, the above-mentioned piping deterioration estimation device can estimate whether the physical property retention rate of the piping component is below a predetermined value, i.e., whether the piping component is deteriorated, based on the acceleration of the impact hammer.

[0020] before The deterioration estimation unit may be configured to estimate that there is a higher probability that the property retention rate of the piping component has decreased below a predetermined value when both the mechanical impedance ZR and the index I obtained by measurement are lower than predetermined threshold values ​​for the mechanical impedance ZR and the index I, respectively, corresponding to the nominal diameter and material of the piping component being measured.

[0021] In addition, it is preferable that the above-mentioned piping component deterioration estimation device further includes a temperature measurement unit and a correction data storage unit that stores correlation data between temperature, the mechanical impedance ZR, and the index I for each nominal diameter and material, and the deterioration estimation unit temperature-compensates the mechanical impedance ZR and the index I obtained by measurement based on the correlation data stored in the correction data storage unit, the nominal diameter and material of the piping component, and the temperature at the time of measurement, and estimates whether the physical property retention rate of the piping component has decreased below a predetermined value based on the temperature-compensated mechanical impedance ZR' and index I'. Effect of the Invention

[0022] According to the present invention, by simply striking the surface of a piping component with an impact hammer and measuring the acceleration of the impact hammer, it is possible to estimate whether the property retention rate of the piping component is below a predetermined value, i.e., whether the piping component has deteriorated, based on the measured acceleration of the impact hammer. Therefore, deterioration of the piping component can be estimated by a simple and inexpensive non-destructive test. Furthermore, since deterioration can be diagnosed by performing non-destructive or destructive testing only on the piping component estimated to be deteriorated, it is possible to reduce the cost for accurate diagnosis. [Brief description of the drawings]

[0023] [Figure 1] 1 is an overall configuration diagram of a piping component deterioration estimation device according to the present invention; [Diagram 2] 2 is a functional block diagram of the piping component deterioration estimating device shown in FIG. 1. [Diagram 3] 2 is an acceleration waveform diagram when a piping component is struck by an impact hammer of the piping component deterioration estimation device shown in FIG. 1. [Figure 4] FIG. 11 is a correlation diagram showing the relationship between the mechanical impedance ZR and the degradation index INDEX of a healthy item and a degraded item for a first piping member. [Diagram 5] FIG. 5 is a diagram showing, for a first piping member, threshold values ​​of the mechanical impedance ZR and the degradation index INDEX for distinguishing between a sound product and a degraded product, superimposed on the correlation diagram shown in FIG. 4. [Figure 6] FIG. 11 is a correlation diagram showing the relationship between the mechanical impedance ZR and the degradation index INDEX for the second piping member, in which thresholds of the mechanical impedance ZR and the degradation index INDEX that distinguish between a healthy product and a degraded product are superimposed. [Figure 7] FIG. 11 is a correlation diagram showing the relationship between the mechanical impedance ZR and the degradation index INDEX for the third piping member, in which thresholds of the mechanical impedance ZR and the degradation index INDEX that distinguish between healthy and degraded products are superimposed. [Figure 8] This is a correlation diagram showing the relationship between temperature and mechanical impedance ZR when the nominal diameter is changed for the same material (pipe type). [Figure 9] FIG. 1 is a correlation diagram showing the relationship between temperature and deterioration index INDEX when the nominal diameter is changed for the same material (pipe type). [Figure 10] This is a correlation diagram showing the relationship between temperature and mechanical impedance ZR when the material (pipe type) is changed while keeping the nominal diameter the same. [Figure 11] This is a correlation diagram showing the relationship between temperature and deterioration index INDEX when the material (pipe type) is changed while keeping the nominal diameter the same. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a piping component deterioration estimating method and a piping component deterioration estimating device according to the present invention will be described with reference to the drawings.

[0025] First, with reference to Figs. 1 and 2, the overall configuration of a piping component deterioration estimation device 11 using a deterioration estimation method for a piping component P according to the present invention will be described.

[0026] The piping component deterioration estimation device (hereinafter simply referred to as the "deterioration estimation device") 11 strikes the surface of a synthetic resin piping component P such as a pipe, joint, elbow, cross, socket, union, valve, etc., and estimates the degree of deterioration based on a judgment as to whether the component is a sound product with a property retention rate equal to or higher than a predetermined value, or a deteriorated product with a property retention rate below a predetermined value. The deterioration estimation device 11 includes an impact hammer 13 for striking the surface of the synthetic resin piping component P to apply an impact, and a measurement analysis device 15 for analyzing the measured value of the acceleration of the impact hammer 13.

[0027] The striking hammer 13 includes a striking part 13a for striking the surface of the piping component P, a grip part 13b connected to the striking part 13a so as to be held by an operator, and an acceleration sensor 17 attached to the surface of the striking part 13a opposite to the striking surface, so that an operator can hold the grip part 13b and strike the surface of the piping component P with the striking part 13a to measure the acceleration of the striking part 13a during striking. The acceleration sensor 17 is connected to the measurement and analysis device 15 via a cable 19 that passes through the grip part 13b and extends to the outside, and the measurement signal measured by the acceleration sensor 17 (i.e., the acceleration of the striking part 13a) can be transmitted to the measurement and analysis device 15.

[0028] The striking portion 13a may have any suitable shape as long as it has a certain mass m and can strike the surface of the piping member P. The acceleration sensor 17 may be any suitable type of acceleration sensor, such as a piezoelectric element type, a semiconductor gauge type, or a resistance wire strain type.

[0029] As shown in detail in Figure 2, the measurement analysis device 15 includes a measurement value memory unit 15a that stores the measurement signal (acceleration of the striking part 13a) transmitted from the acceleration sensor 17 via the cable 19, a threshold value memory unit 15b that stores predetermined threshold values ​​for the mechanical impedance ZR and the deterioration index INDEX described below, a correction data memory unit 15c that stores data for temperature correction of the mechanical impedance ZR and the deterioration index INDEX, a deterioration estimation unit 15d that estimates the deterioration of the piping member P based on the measurement value by the acceleration sensor 17, a display unit 15e for displaying the results estimated by the deterioration estimation unit 15d, and a temperature measurement unit 15f for measuring the temperature of the measurement environment.

[0030] When the surface of the piping component P is struck by the striking hammer 13, the surface of the piping component P undergoes elastic deformation or in addition slight plastic deformation due to the impact of the striking hammer 13, and at the same time the striking hammer 13 receives a reaction force due to the deformation from the surface of the piping component P. As a result, after the striking hammer 13 collides with the striking part 13a of the striking hammer 13 at time t = T1, the striking hammer 13 is decelerated by the reaction force from the surface of the piping component P from the initial collision velocity Va (hereinafter also simply referred to as the "collision velocity") at the moment the striking part 13a collides with the surface of the piping component P at an acceleration a(t) to a velocity of 0 at time t = T2, and is further accelerated by the acceleration a(t) in the opposite direction to the velocity direction at the time of collision, and at time t = T3 the striking part 13a separates from the surface of the piping component P, at which moment the acceleration a(t) becomes 0 and the rebound velocity becomes the maximum rebound velocity (hereinafter also simply referred to as the "rebound velocity") Vr. Here, t means time, and acceleration a(t) means the acceleration of the striking hammer 13 at time t. Therefore, the collision velocity Va is calculated by integrating the acceleration a(t) from time t = T1 to time t = T2, and the repulsion velocity Vr is calculated by integrating the acceleration a(t) from time t = T2 to time t = T3. In addition, the striking force F(t) generated on the surface of the piping component P by the striking hammer 13 can be calculated by the formula F(t) = m a(t), where m is the mass of the striking hammer 13.

[0031] Assuming that most of the deformation of the piping component P is elastic deformation, the repulsive force from the surface of the piping component P becomes maximum when the velocity V of the striking hammer 13 becomes 0, and the acceleration a(t) becomes maximum when the velocity V of the striking hammer 13 becomes 0. Therefore, as shown in FIG 3, the acceleration a(t) at time t becomes 0 at time t=T1 when the striking part 13a of the striking hammer 13 collides with the surface of the piping component P, and at time t=T3 when the striking part 13a of the striking hammer 13 separates from the surface of the piping component P, and reaches the maximum value a(t) at time t=T2 when the velocity V of the striking hammer 13 becomes 0. max In addition, the impact force F reaches a maximum value F at time t = T2. max F max is the formula F max =m·a max In the following explanation, the period from time t=T1 to time t=T2 is referred to as the penetration process, and the period from time t=T2 to time t=T3 is referred to as the repulsion process.

[0032] On the other hand, the deterioration of the synthetic resin piping member P is generally diagnosed by the property retention rate. When the property retention rate of the piping member P decreases, the repulsive force when the piping member P is struck also decreases, and the maximum acceleration a max That is, the maximum impact force F max , and the maximum rebound velocity Vr. From this, the inventors have concluded that the property retention rate of the piping component P affects the acceleration of the striking hammer 13 during the recovery of the piping component P from deformation after being struck by the striking hammer 13, i.e., during the rebound process, and that the maximum impact force F max The mechanical impedance of the rebound process is ZR=F, which is the value obtained by dividing by the maximum rebound velocity Vr. max It has been found that the deterioration of the piping component P, that is, the decrease in the property retention rate of the piping component P, can be estimated based on the deterioration index INDEX=Va / Vr, which is the ratio of the impact speed Va to the rebound speed Vr. It goes without saying that the deterioration index INDEX may be Vr / Va.

[0033] The mechanical impedance ZR of the repulsion process depends on the impact velocity Va. maxis obtained by dividing by Vr, which depends on the impact speed Va, so it is a value that is not affected by the impact speed Va, and the deterioration index INDEX is also a ratio between the impact speed Va and the rebound speed Vr, so it is a value that is not affected by the impact speed Va. Therefore, it is not affected by the strength of the impact. In addition, the effect of the decrease in the property retention rate of the piping component P appears in the rebound process, so the mechanical impedance ZA of the penetration process is F max / Va, but the mechanical impedance of the repulsion process ZR=F max / Vr is used as an index for estimating deterioration.

[0034] Furthermore, the inventors have found that the mechanical impedance ZR and the deterioration index INDEX in the rebound process of the synthetic resin piping member P depend on temperature. Therefore, the temperature during measurement for estimating the decrease in the property retention rate (i.e., deterioration) is measured by the temperature measuring unit 15f based on the temperature during measurement for determining a threshold value described later, and the mechanical impedance ZR and the deterioration index INDEX in the rebound process obtained from the measured value of acceleration are temperature-compensated based on the measured temperature, thereby making it possible to more accurately estimate the decrease in the property retention rate (i.e., deterioration) of the piping member P.

[0035] Based on the above-mentioned findings of the present inventor, the deterioration estimation unit 15d estimates whether or not the property retention rate of the piping component P falls below a predetermined value based on the mechanical impedance ZR in the rebound process and the deterioration index INDEX obtained from the measurement value by the acceleration sensor 17. Below, a detailed explanation will be given of an example of a method in which the deterioration estimation unit 15d of the illustrated piping component deterioration estimation device 11 estimates a decrease in the property retention rate of the piping component P based on the measurement value of the acceleration of the striking hammer 13 by the acceleration sensor 17.

[0036] First, a plurality of piping members P are divided into healthy and deteriorated ones based on a predetermined property retention rate for each pipe type and nominal diameter of the piping members P, and for each, a mechanical impedance ZR in the rebound process and a deterioration index INDEX are calculated from the measured value of acceleration a(t) obtained by striking with the striking hammer 13, and thresholds for ZR and INDEX between healthy and deteriorated ones are determined in advance and stored in the threshold storage unit 15b. It is preferable that the measurement for determining the thresholds is performed under specific temperature conditions. The material of the piping members P is determined by the pipe type. In addition, since the nominal diameter of the piping members P is generally determined according to a standard, once the nominal diameter is specified, the outer diameter and thickness (i.e., the inner diameter) are specified based on the standard. Therefore, determining threshold values ​​for the mechanical impedance ZR and the deterioration index INDEX between healthy and degraded products for each pipe type and nominal diameter of the piping component P means determining threshold values ​​for the mechanical impedance ZR and the deterioration index INDEX between healthy and degraded products for each material, outer diameter, and thickness (i.e., inner diameter) of the piping component P.

[0037] It is also preferable to measure the acceleration a(t) by performing tapping with the striking hammer 13 while changing the temperature conditions for each pipe type and nominal diameter of the piping member P, calculate the mechanical impedance ZR and the deterioration index INDEX in the rebound process from the measured value of the acceleration a(t), and obtain in advance the correlation between the temperature and the mechanical impedance ZR and the deterioration index INDEX, and store it in advance in the correction data storage unit 15c. When the pipe type and nominal diameter of the piping member P are determined, the temperature, the mechanical impedance ZR, and the deterioration index INDEX can be approximated by a linear function, so that, for example, the approximated linear function may be stored in the correction data storage unit 15c. Also, a temperature correction coefficient for each temperature may be determined based on the temperature conditions at the time of measurement for determining the threshold value, and the temperature correction coefficient may be stored in the correction data storage unit 15c.

[0038] Next, the impact hammer 13 strikes the surface of the synthetic resin piping member P to be diagnosed, and the acceleration a(t) of the impact hammer 13 measured by the acceleration sensor 17 is measured over time and stored in the measurement value storage unit 15a.max It is preferable to determine upper and lower limits of the acceleration a(t) and use only the measured value when the maximum impact force falls within the range between the upper and lower limits. max and the time T2 at which this value was observed. In the deterioration estimation unit 15d, the collision velocity Va is calculated by time integrating the acceleration a(t) from the measured values ​​over time stored in the measurement value storage unit 15a over the time period from 0 to the maximum value (i.e., from time T1 to time T2), and the rebound velocity Vr is calculated by time integrating the acceleration a(t) from the measured values ​​over time stored in the measurement value storage unit 15a over the time period from the maximum value to the time when it decreases back to 0 (i.e., from time T2 to time T3). In addition, the maximum acceleration a(t) is calculated from the measured values ​​over time stored in the measurement value storage unit 15a. max Since the mass m of the striking hammer 13, which is known in advance, and the measured value of the acceleration a(t) over time stored in the measured value storage unit 15a are used, the formula F max =m·a max The maximum impact force F generated when the impact part 13a of the impact hammer 13 impacts the surface of the piping member P is max The collision speed Va, the rebound speed Vr, and the maximum impact force F are calculated in this way. max From the above, the deterioration estimation unit 15d calculates the following equation: ZR=F max Based on / Vr and the equation INDEX=Va / Vr, the mechanical impedance ZR and the deterioration index INDEX during the rebound process are calculated.

[0039] After obtaining the mechanical impedance ZR and the deterioration index INDEX in the rebound process, the deterioration estimation unit 15d preferably measures the temperature at the time of measurement for estimating the deterioration by the temperature measurement unit 15f, and performs temperature correction on the mechanical impedance ZR and the deterioration index INDEX obtained as described above according to the temperature conditions at the time of measurement based on the temperature correction data stored in the correction data storage unit 15c. As described above, the temperature correction may be performed, for example, by storing an approximation function of the mechanical impedance ZR and the deterioration index INDEX with respect to temperature in the correction data storage unit 15c and using the approximation function stored in the correction data storage unit 15c, or by storing a correction coefficient for the mechanical impedance ZR and the deterioration index INDEX at each temperature based on the temperature conditions at the time of measurement for determining the threshold value in the correction data storage unit 15c and using the correction coefficient stored in the correction data storage unit 15c, and the correction method is not limited. By performing the temperature correction in this manner, it is possible to estimate the deterioration more accurately.

[0040] When temperature correction is performed, the deterioration estimation unit 15d uses the values ​​of the mechanical impedance ZR' and the deterioration index INDEX' obtained by temperature correcting the mechanical impedance ZR and the deterioration index INDEX obtained from the measured value of the acceleration due to tapping of the piping component P to be diagnosed using the method described above.When temperature correction is not performed, the deterioration estimation unit 15d uses the values ​​of the mechanical impedance ZR and the deterioration index INDEX obtained from the measured value of the acceleration due to tapping of the piping component P to be diagnosed and compares them with the threshold values ​​corresponding to the pipe type and nominal diameter of the piping component P to be diagnosed among the threshold values ​​of the mechanical impedance ZR and the deterioration index INDEX pre-stored in the threshold memory unit 15b. When at least one of the mechanical impedance ZR and the deterioration index INDEX of the piping member P to be diagnosed, or at least one of the mechanical impedance ZR' and the deterioration index INDEX' after temperature correction is below the threshold value of the mechanical impedance ZR and the deterioration index INDEX pre-stored in the threshold value storage unit 15b corresponding to the pipe type and the nominal diameter of the piping member P to be diagnosed, the deterioration estimation unit 15d estimates that the physical property retention rate of the piping member P to be diagnosed is below a predetermined value, that is, that it is a deteriorated product, and displays the estimation result on the display unit 15e. On the other hand, when both the mechanical impedance ZR and the deterioration index INDEX of the piping member P to be diagnosed, or both the mechanical impedance ZR' and the deterioration index INDEX' after temperature correction are equal to or greater than the threshold value of the mechanical impedance ZR and the deterioration index INDEX pre-stored in the threshold value storage unit 15b corresponding to the pipe type and the nominal diameter of the piping member P to be diagnosed, the deterioration estimation unit 15d estimates that the physical property retention rate of the piping member P to be diagnosed is equal to or greater than the predetermined value, that is, that it is a sound product, and displays the estimation result on the display unit 15e. In addition, when both the mechanical impedance ZR and the deterioration index INDEX of the piping component P to be diagnosed and both the temperature-corrected mechanical impedance ZR' and the deterioration index INDEX' fall below the threshold values ​​of the mechanical impedance ZR and the deterioration index INDEX pre-stored in the threshold memory unit 15b corresponding to the pipe type and nominal diameter of the piping component P to be diagnosed, the deterioration estimation unit 15d estimates that there is a higher probability that the physical property retention rate of the piping component P to be diagnosed is below a predetermined value, i.e., that there is a higher probability that it is a degraded product, and may display this on the display unit 15e.

[0041] In this way, by using the piping component deterioration estimation device 11, the deterioration estimation method for the piping component P according to the present invention can be implemented, and the decrease in the property retention rate of the piping component P, i.e., the deterioration, can be estimated by simply measuring the acceleration of the striking hammer 13 when hitting the piping component P to be diagnosed. Therefore, even if the entire piping system is inspected, it is possible to estimate the deteriorated part in a short time and at a low cost. Furthermore, if a more accurate diagnosis is required, the piping component P estimated to be deteriorated may be subjected to ultrasonic flaw detection test, radiographic test, or destructive test, which have been conventionally performed as non-destructive inspection methods. If the conventional non-destructive test is performed only on the piping component P estimated to be deteriorated by the piping component deterioration estimation device 11 or the deterioration estimation method for the piping component P according to the present invention, it is possible to significantly shorten the inspection time and greatly reduce the cost compared to the case of performing the conventional non-destructive test on the entire piping system. Furthermore, by using the piping component deterioration estimation device 11 or the deterioration estimation method for the piping component P according to the present invention, it is possible to narrow down the parts where the property retention rate of the piping component P is likely to decrease (i.e., the parts where the deterioration is likely to occur), making it easier to apply the radiographic test. Furthermore, by conducting destructive testing only on piping components P that are estimated to be deteriorated by the piping component deterioration estimation device 11 and the deterioration estimation method for piping components P according to the present invention, it becomes possible to shorten the downtime of operation, since only the minimum number of parts need to be replaced. EXAMPLES

[0042] Figure 4 shows a correlation diagram showing the relationship between the mechanical impedance ZR and the deterioration index INDEX obtained in an experiment in which the mechanical impedance ZR and the deterioration index INDEX during the rebound process were obtained from the acceleration a(t) of the striking hammer 13 measured when each specimen was struck by the striking hammer 13, using straight rigid polyvinyl chloride pipes (manufactured by Asahi Yukizai, pipe type: VP200A) with a nominal diameter of 200 mm in various states according to the JIS K6741:2016 standard as test specimens. In the experiment, the physical property retention rates such as the elongation retention rate and the impact strength retention rate were measured in advance for each specimen, and specimens with all physical property retention rates of 50% or more were classified as sound products, and those with any one physical property retention rate of less than 50% were classified as degraded products. In Figure 4, the results obtained from sound products are indicated by "○" and the results obtained from degraded products are indicated by "×". From Fig. 4, for example, as shown in Fig. 5, it can be seen that, with the mechanical impedance ZR = 1.12 and the deterioration index INDEX = 0.69 set as respective thresholds, whether the physical property retention rate is less than 50%, i.e., whether the product is deteriorated or sound, can be estimated depending on whether the mechanical impedance ZR and the deterioration index INDEX measured in the piping component P to be diagnosed are below the respective thresholds. Note that if the standard is followed, the outer diameter, inner diameter, thickness, etc. are specified once the nominal diameter is determined.

[0043] FIG. 6 shows a correlation diagram showing the relationship between the mechanical impedance ZR and the deterioration index INDEX obtained by performing an experiment to obtain the mechanical impedance ZR and the deterioration index INDEX during the rebound process from the acceleration a(t) of the striking hammer 13 measured when each test specimen was struck by the striking hammer 13, using heat-resistant rigid polyvinyl chloride straight pipes (manufactured by Asahi Yukizai Co., Ltd., pipe type: HT100A) with a nominal diameter of 100 mm in various states according to the JIS K6776:2016 standard as test specimens. As in the cases shown in FIG. 4 and FIG. 5, the physical property retention rates such as the elongation retention rate and the impact strength retention rate were measured in advance for each test specimen, and those with all physical property retention rates of 50% or more were classified as sound products, and those with any one physical property retention rate of less than 50% were classified as degraded products. In FIG. 6, the results obtained from sound products are indicated by "○" and the results obtained from degraded products are indicated by "×". From Figure 6, for example, it can be seen that, when the mechanical impedance ZR and the deterioration index INDEX measured in the piping component P to be diagnosed are set as the respective threshold values ​​of ZR = 0.77 and INDEX = 0.60, it is possible to estimate whether the property retention rate is less than 50%, i.e., whether the component is degraded or healthy, depending on whether the mechanical impedance ZR and the deterioration index INDEX measured in the piping component P to be diagnosed are below the respective threshold values.

[0044] Fig. 7 is a correlation diagram showing the relationship between the mechanical impedance ZR and the deterioration index INDEX obtained by an experiment in which the mechanical impedance ZR and the deterioration index INDEX during the rebound process were obtained from the acceleration a(t) of the striking hammer 13 measured when each specimen was struck by the striking hammer 13, in accordance with the standard JIS K6741:2016. The specimens were straight pipes with a nominal diameter of 150 mm (manufactured by Asahi Yukizai Co., Ltd., pipe type: Chojun 150A) made of hard polyvinyl chloride with a different composition from the above-mentioned VP200A, and the specimens were compliant with the standard JIS K6741:2016. In the experiment, the physical property retention rates such as the elongation retention rate and the impact strength retention rate were measured in advance for each specimen, as in the cases shown in Figs. 4 and 5. The specimens with all physical property retention rates of 50% or more were classified as sound products, and the specimens with any one physical property retention rate of less than 50% were classified as degraded products. In Fig. 7, the results obtained from sound products are indicated by "○" and the results obtained from degraded products are indicated by "×". From Figure 7, for example, it can be seen that, when the mechanical impedance ZR and the deterioration index INDEX measured in the piping component P to be diagnosed are set as threshold values ​​of 1.0 and 0.65, respectively, it is possible to estimate whether the property retention rate is less than 50%, i.e., whether the component is degraded or healthy, depending on whether the mechanical impedance ZR and the deterioration index INDEX measured in the piping component P to be diagnosed are below their respective threshold values.

[0045] From the results shown in Figures 4 to 7, it can be seen that by predetermining threshold values ​​for the mechanical impedance ZR and the deterioration index INDEX in the repulsion process for each material (pipe type) and nominal diameter (outer diameter, inner diameter or thickness), it is possible to estimate the deterioration of the piping component P to be diagnosed if the material (pipe type) and nominal diameter (outer diameter, inner diameter or thickness) are identified.

[0046] 8 and 9 are correlation diagrams showing the relationship between temperature and mechanical impedance ZR and deterioration index INDEX obtained from the experimental results. The experiment was conducted by using straight pipes made of hard polyvinyl chloride (manufactured by Asahi Yukizai Co., Ltd., pipe type VP) with different nominal diameters as test specimens, changing the temperature conditions, and measuring the acceleration a(t) of the striking hammer 13 when striking each test specimen with the striking hammer 13 under each temperature condition. FIG. 8 shows the correlation between temperature and mechanical impedance ZR in the rebound process, and FIG. 9 shows the correlation between temperature and deterioration index INDEX. In the experiment, an unused straight pipe was used as the test specimen. In FIG. 8 and FIG. 9, the results obtained from a straight pipe with a nominal diameter of 25 mm are shown as "○", the results obtained from a straight pipe with a nominal diameter of 100 mm are shown as "×", the results obtained from a straight pipe with a nominal diameter of 150 mm are shown as "△", and the results obtained from a straight pipe with a nominal diameter of 200 mm are shown as "□". From Fig. 8, it can be seen that if the pipe type, i.e., material, is specified, for straight pipes of each nominal diameter, the mechanical impedance ZR in the rebound process decreases almost linearly with increasing temperature and can be approximated by a linear function with a negative gradient with respect to temperature. Similarly, from Fig. 9, it can be seen that if the pipe type, i.e., material, is specified, for straight pipes of each nominal diameter, the deterioration index INDEX decreases almost linearly with increasing temperature and can be approximated by a linear function with a negative gradient with respect to temperature.

[0047] Figures 10 and 11 show correlation diagrams showing the relationship between temperature and mechanical impedance ZR and deterioration index INDEX obtained from the experimental results. Test specimens were straight pipes (manufactured by Asahi Yukizai Co., Ltd., pipe types VP, HI, and HT) with the same nominal diameter. The test specimens were struck by the striking hammer 13 under different temperature conditions. The mechanical impedance ZR and deterioration index INDEX were obtained from the acceleration a(t) of the striking hammer 13 measured during the rebound process. The material of the VP pipe type was hard polyvinyl chloride, the material of the HI pipe was impact-resistant hard polyvinyl chloride, and the material of the HT pipe was heat-resistant hard polyvinyl chloride. Figure 10 shows the correlation between temperature and mechanical impedance ZR during the rebound process, and Figure 11 shows the correlation between temperature and deterioration index INDEX. In the experiment, an unused straight pipe was used as the test specimen. In Figures 10 and 11, the results obtained from a straight pipe made of rigid polyvinyl chloride with a nominal diameter of 100 mm are indicated by "x", the results obtained from a straight pipe made of impact-resistant rigid polyvinyl chloride with a nominal diameter of 100 mm are indicated by "△", and the results obtained from a straight pipe made of heat-resistant rigid polyvinyl chloride with a nominal diameter of 100 mm are indicated by "□". From Figure 10, it can be seen that if the nominal diameter is specified, for a straight pipe of a material, the mechanical impedance ZR in the rebound process decreases almost linearly with increasing temperature and can be approximated by a linear function with a negative gradient with respect to temperature. Similarly, from Figure 9, it can be seen that if the pipe type, i.e., material, is specified, for straight pipes of each nominal diameter, the deterioration index INDEX decreases almost linearly with increasing temperature and can be approximated by a linear function with a negative gradient with respect to temperature.

[0048] From the results shown in Figures 8 to 11, it can be seen that if the material (pipe type) and nominal diameter (outer diameter, inner diameter or thickness) are specified, the mechanical impedance ZR and deterioration index INDEX in the repulsion process change approximately according to a linear function with respect to temperature for each material (pipe type) and outer diameter (outer diameter, inner diameter or thickness). Therefore, if a linear function that approximates the change in the mechanical impedance ZR and deterioration index INDEX in the repulsion process with respect to temperature is obtained in advance for each material (pipe type) and outer diameter (outer diameter, inner diameter or thickness), and the mechanical impedance ZR and deterioration index INDEX in the repulsion process obtained from the measurement are temperature-compensated based on the temperature at the time of measurement, it becomes possible to suppress the influence of temperature. It goes without saying that the same effect can be obtained by determining in advance from the above linear function the correction coefficients for the mechanical impedance ZR and the deterioration index INDEX at each temperature based on the temperature at the time of measurement to determine the threshold values ​​of the mechanical impedance ZR and the deterioration index INDEX in the rebound process for each material (pipe type) and outer diameter (outer diameter, inner diameter or thickness), and temperature-correcting the mechanical impedance ZR and the deterioration index INDEX in the rebound process obtained from the measurement using the correction coefficients based on the temperature at the time of measurement. If the above-mentioned deterioration estimation method for the piping component P is performed based on the temperature-corrected mechanical impedance ZR' and the deterioration index INDEX', the effect of temperature can be suppressed and the decrease in the property retention rate of the piping component P, i.e., the deterioration, can be estimated more accurately.

[0049] The deterioration estimation method and the deterioration estimation device for a piping component P according to the present invention have been described above with reference to the illustrated embodiment, but the present invention is not limited to the illustrated embodiment. For example, in the piping component deterioration estimation device 11 of the illustrated embodiment, the measurement and analysis device 15 is provided with a display unit 15e, and the estimation result regarding deterioration is displayed on the display unit 15e, but it is also possible for the measurement and analysis device 15 to be provided with an alarm unit, and for the alarm unit to emit an alarm sound when deterioration is estimated. Also, in the illustrated piping component deterioration estimation device 11, the impact hammer 13 and the measurement and analysis device 15 are configured as separate bodies, but the measurement and analysis device 15 may be formed integrally with the impact hammer 13. [Explanation of symbols]

[0050] 11 Piping component deterioration estimation device 13 Impact hammer 13a Striking section 13b Grip part 15 Measurement and analysis equipment 15a Measurement value memory section 15b Threshold memory unit 15c Correction data storage section 15d Deterioration Estimation Section 15e Display section 17 Acceleration Sensor 19 Cable

Claims

1. A method for estimating deterioration of a piping component, which estimates a decrease in a property retention rate of a synthetic resin piping component by using a measuring device including an impact hammer and an acceleration sensor attached to the impact hammer, comprising: The impact hammer strikes a surface of a synthetic resin piping member, and the acceleration sensor measures the acceleration of the impact hammer over time. From the measured acceleration of the impact hammer, at least one of a mechanical impedance ZR during the rebound process in which the impact hammer rebounds from the surface of the piping component in the direction opposite to when the impact hammer impacted the surface of the piping component, and an index I calculated from the collision velocity Va when the impact hammer collides with the surface of the piping component and the rebound velocity Vr when the impact hammer rebounds from the surface of the piping component using the equation I = Va / Vr is calculated, and based on at least one of the calculated mechanical impedance ZR and index I, it is estimated whether or not the physical property retention rate of the piping component has decreased below a predetermined value; The crash velocity Va is calculated by integrating the measured acceleration over a time period from 0 to a maximum value; The rebound velocity Vr is calculated by integrating the measured acceleration over time from a maximum value until it decreases back to zero; When the maximum value of the impact force generated when the impact hammer collides with the surface of the piping component is defined as F max , F max is calculated from the mass of the impact hammer and the measured acceleration of the impact hammer, The mechanical impedance ZR is calculated by the formula ZR=F max / Vr; A threshold value is previously determined for each of the mechanical impedance ZR and the index I, A method for estimating deterioration of a piping component, characterized in that when at least one of the mechanical impedance ZR and the index I obtained by measurement falls below a predetermined threshold value for each of the mechanical impedance ZR and the index I, it is estimated that the physical property retention rate of the piping component has decreased below a predetermined value.

2. 2. The deterioration estimation method for a piping component as described in claim 1, wherein when both the mechanical impedance ZR and the index I obtained by measurement fall below respective predetermined threshold values ​​for the mechanical impedance ZR and the index I, it is estimated that there is a higher probability that the physical property retention rate of the piping component has decreased below a predetermined value.

3. 3. The method for estimating thickness according to claim 1, wherein threshold values ​​are predefined for the mechanical impedance ZR and the index I for each nominal diameter and material of the synthetic resin piping component, and the method estimates whether the physical property retention rate of the piping component has decreased below a predefined value by comparing the predefined threshold values ​​for the mechanical impedance ZR and the index I corresponding to the nominal diameter and material of the piping component to be measured with the mechanical impedance ZR and the index I obtained by measurement.

4. 4. A method for estimating deterioration of a piping component according to claim 1, further comprising: determining in advance a correlation between temperature and the mechanical impedance ZR and the index I; temperature-compensating the mechanical impedance ZR and the index I determined by measurement based on the previously determined correlation and the temperature at the time of measurement; and estimating whether or not the physical property retention rate of the piping component has decreased below a predetermined value based on at least one of the temperature-compensated mechanical impedance ZR' and index I'.

5. A piping component deterioration estimation device that estimates a decrease in a property retention rate of a piping component made of a synthetic resin, comprising: A striking hammer for striking a surface of a synthetic resin piping component; An acceleration sensor attached to the striking hammer; a measurement value storage unit that stores the acceleration of the striking hammer measured by the acceleration sensor over time; a deterioration estimation unit that estimates whether a property retention rate of the piping member is lower than a predetermined value based on the acceleration stored in the measurement value storage unit; a threshold value storage unit that stores predetermined threshold values ​​for the mechanical impedance ZR and the index I for each nominal diameter and material of the piping member; Equipped with The deterioration estimation unit obtains, from the acceleration stored in the measurement value storage unit, at least one of a mechanical impedance ZR during the rebound process in which the impact hammer rebounds from the surface of the piping component in the direction opposite to the direction of impact with the surface of the piping component, and an index I calculated by the equation I=Va / Vr from the collision speed Va when the impact hammer collides with the surface of the piping component and the rebound speed Vr when the impact hammer rebounds from the surface of the piping component; and estimates that when both the mechanical impedance ZR and the index I obtained by measurement are lower than predetermined threshold values ​​for the mechanical impedance ZR and the index I corresponding to the nominal diameter and material of the piping component to be measured, there is a higher probability that the physical property retention rate of the piping component has decreased below a predetermined value, The collision velocity Va is calculated by integrating the acceleration stored in the measurement value storage unit over a time period during which the acceleration increases from 0 to a maximum value, The rebound velocity Vr is calculated by integrating the acceleration stored in the measurement value storage unit over a time period from a maximum value until the acceleration decreases to 0 again, When the maximum value of the impact force generated when the impact hammer collides with the surface of the piping component is F max , F max is calculated from the mass of the impact hammer and the acceleration of the impact hammer stored in the measurement value storage unit, The piping component deterioration estimating device is characterized in that the mechanical impedance ZR is calculated by the formula ZR=F max / Vr.

6. 6. The piping component deterioration estimation device of claim 5, wherein the deterioration estimation unit estimates that there is a higher probability that the physical property retention rate of the piping component has decreased below a predetermined value when both the mechanical impedance ZR and the index I obtained by measurement are lower than respective predetermined threshold values ​​for the mechanical impedance ZR and the index I corresponding to the nominal diameter and material of the piping component to be measured.

7. 7. The piping component deterioration estimation device according to claim 5 or claim 6, further comprising a temperature measuring unit and a correction data storage unit that stores correlation data between temperature, the mechanical impedance ZR, and the index I for each nominal diameter and material, wherein the deterioration estimation unit temperature-compensates the mechanical impedance ZR and the index I obtained by measurement based on the correlation data stored in the correction data storage unit, the nominal diameter and material of the piping component, and the temperature at the time of measurement, and estimates whether or not the physical property retention rate of the piping component has decreased below a predetermined value based on the temperature-compensated mechanical impedance ZR' and index I'.

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