Corrosion management system, estimation method and program

Abstract

To provide means of estimating the state of corrosion of an unmeasured site.SOLUTION: A corrosion management system is provided, comprising a measurement data acquisition unit configured to acquire measurement data indicative of the state of corrosion at a first site of an evaluation target structure, and a corrosion estimation unit configured to estimate the state of corrosion at a second site on the basis of a relational expression between the state of corrosion at the first site under evaluation and the state of corrosion at the second site, and the measurement data of the first site.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a corrosion management system, an estimation method, and a program.

Background Art

[0002] In order to maintain the soundness of structures in many fields such as ships, chemical plants, and thermal power plants, countermeasures against corrosion have become an important issue. Corrosion thinning is a phenomenon with large variations, and inferences based on probability statistics are used. When predicting the corrosion state, a two-stage corrosion model of corrosion occurrence and corrosion progress, or a three-stage corrosion model that takes into account the transition from occurrence to progressive corrosion between corrosion occurrence and progress is used.

[0003] The prediction of the corrosion progress amount (thinning amount) of steel materials generally uses the power law Y = AX B (where Y is the corrosion amount, X is the time, and A and B are coefficients depending on the material and the environment). Methods for determining the coefficients A and B include (1) a method of estimating using observable physical quantities as explanatory variables, and (2) a method of directly estimating from experimental and measured values.

[0004] Patent Document 1 discloses a method for obtaining the corrosion amount by probabilistic inference using temperature, relative humidity, flying salt content, and wetting probability at the installation location of a bridge as explanatory variables. The method disclosed in Patent Document 1 cannot be used unless the explanatory variables are clear, but there are cases where explanatory variables cannot be obtained for measurement reasons. For example, in large structures, areas where sensors are not installed are common. Also, normal sensors cannot be installed in explosion-proof areas. When measurement values in such areas are included in the explanatory variables, the method of Patent Document 1 cannot be used. Further, in the method of Patent Document 1, when the number of explanatory variables increases, the standard error of corrosion amount estimation may increase due to the adjustment of the degree of freedom of regression.

[0005] In the method described in Non-Patent Document 1, using a large amount of measurement data obtained from each part of the hull, the coefficients of the three-stage corrosion model are adjusted, and the occurrence life of corrosion and the amount of corrosion at an arbitrary time are stochastically estimated. However, in the inspection and measurement of corrosion of large structures such as ships, it is often impossible to obtain measurement data sufficient for statistical inference for all structural members from the viewpoints of time, cost, safety, etc., including accessibility. In addition, there are the following risks regarding the measurement data of a single structural member among large structures. (1) Since the sample size of inspection and measurement is small (the number that can be sampled as a sample) , the statistical distribution tendency cannot be grasped. (2) There is a bias in inspection and measurement, and the target part is not representative. (3) There are measurement errors due to the working environment, the characteristics of inspection instruments, the ability of workers, etc. In addition, (4) even if data is accumulated for a certain structure, it may not be valid data for structures with different conditions such as environment and operation.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Non-Patent Documents

[0007]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] There is a need for a method that can estimate the corrosion state even for parts where corrosion inspection and measurement results have not been obtained for some reason.

[0009] The present disclosure provides a corrosion management system, an estimation method, and a program that can solve the above problems.

Means for Solving the Problems

[0010] The corrosion management system of the present disclosure includes a measurement data acquisition unit that acquires measurement data indicating the corrosion state at a first part of a structure to be evaluated, and a relational expression between the corrosion state at the first part of the evaluation target and the corrosion state at a second part, and a corrosion estimation unit that estimates the corrosion state at the second part based on the measurement data at the first part. , the relational expression includes a first relational expression indicating the relationship between the corrosion occurrence life of the first part and the corrosion occurrence life of the second part, and a second relational expression indicating the relationship between the corrosion progress amount of the first part and the corrosion progress amount of the second part.

[0011] The estimation method of the present disclosure includes a step of acquiring measurement data indicating the corrosion state at a first part of a structure to be evaluated, and a step of estimating the corrosion state at the second part based on a relational expression between the corrosion state at the first part of the evaluation target and the corrosion state at the second part, and the measurement data at the first part. , the relational expression includes a first relational expression indicating the relationship between the corrosion occurrence life of the first part and the corrosion occurrence life of the second part, and a second relational expression indicating the relationship between the corrosion progress amount of the first part and the corrosion progress amount of the second part.

[0012] The program of the present disclosure causes a computer to perform a step of acquiring measurement data indicating the corrosion state at a first part of a structure to be evaluated, and a step of estimating the corrosion state at the second part based on a relational expression between the corrosion state at the first part of the evaluation target and the corrosion state at the second part, and the measurement data at the first part. has, and the relational expression includes a first relational expression indicating the relationship between the corrosion occurrence life of the first part and the corrosion occurrence life of the second part, and a second relational expression indicating the relationship between the corrosion progress amount of the first part and the corrosion progress amount of the second part, the process to execute.

Advantages of the Invention

[0013] According to the above-described corrosion management system, estimation method, and program, the corrosion state of unmeasured points can be estimated. Also, an effective maintenance plan for dealing with the estimated corrosion can be created.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0015] <Embodiment> Hereinafter, the corrosion management system of the present disclosure will be described with reference to FIGS. 1 to 7. (System Configuration) FIG. 1 is a block diagram showing an example of a corrosion management system according to an embodiment. The corrosion management system 1 estimates the corrosion state of structures in floating structures such as ships, and various facilities and machines such as chemical plants, further predicts the future failure probability caused by corrosion, and creates an effective maintenance plan to address such failures. For structures where corrosion is an issue, corrosion inspections and measurements are carried out. However, for large structures such as ships, inspections and measurements are not necessarily possible for all parts that need attention. In contrast, when sufficient inspection data cannot be obtained for the evaluation target, or for parts where inspection data cannot be frequently obtained, the corrosion management system 1 refers to the past corrosion database for the evaluation target, obtains the time-series changes of the corrosion occurrence life (the time until corrosion occurs) and the corrosion amount (weight loss amount) of each part, and probabilistically estimates the corrosion occurrence life and the corrosion amount from these data and the limited measurement data of the evaluation target.

[0016] The corrosion management system 1 includes a corrosion estimation device 10 and a maintenance plan device 20. The corrosion estimation device 10 estimates the corrosion state of unmeasured parts of the evaluation target. The maintenance plan device 20 creates a maintenance plan for corrosion that optimizes reliability or cost based on the corrosion state estimated by the corrosion estimation device 10.

[0017] (Configuration of the Corrosion Estimation Device) The corrosion estimation device 10 includes a measurement data acquisition unit 11, a relational expression calculation unit 12, a corrosion estimation unit 13, a measurement data correction unit 14, a failure probability calculation unit 15, a storage unit 16, and an output unit 17. The measurement data acquisition unit 11 acquires measurement data, which is information indicating the corrosion state inspected and measured for the structure of the evaluation target. The measurement data includes information such as the presence or absence of corrosion and the weight loss amount. There is no limitation on the structure of the evaluation target. In the following description, as an example, the evaluation target is assumed to be a ship H. Also, the part where the measurement data is obtained is referred to as part S, and the part where the measurement data is not obtained but the corrosion evaluation is to be performed is referred to as part U. Here, a part is a structure having a certain size, such as the upper deck, side shell, ballast water tank, and oil tank of the ship H.

[0018] The relational expression calculation unit 12 calculates the relationship between part U and part S from the measurement data of part U and part S in other ships in the past. The relational expression calculation unit 12 calculates a relational expression of the corrosion occurrence life showing the relationship between the period until corrosion occurs in part U and the period until corrosion occurs in part S, and a relational expression of the corrosion amount showing the relationship between the corrosion amount (weight loss amount) of part U and the corrosion amount of part S at time T. Even within part S, the corrosion occurrence life and the corrosion amount vary depending on the actually measured position, and the relationship regarding the corrosion between part U and part S also differs between ship 1 and ship 2 for which the measurement data of part U and part S are both obtained. Therefore, the relational expression calculation unit 12 calculates a relational expression of the corrosion occurrence life and a relational expression of the corrosion amount that include these uncertainties.

[0019] Next, referring to FIG. 2, these relational expressions will be described. For many marine structures such as ships, a corrosion database of each member based on the results of past corrosion inspections is provided. The corrosion database contains data on various ships and includes data encompassing all structural and usage environment differences.

[0020] The following information (parameters) analyzed based on the measurement data measured for each part is stored in the corrosion database. · Probability database of corrosion occurrence life Tc... For example, the logarithmic mean and logarithmic standard deviation of the corrosion occurrence life Tc are registered. · Probability database of corrosion progress parameter a... For example, the logarithmic mean and logarithmic standard deviation of the corrosion progress parameter a are registered. · Database of corrosion progress parameter b... b is, for example, a fixed value determined for each material and part (location, environment). Or b may be a random variable.

[0021] The corrosion progress parameters a and b are A and B in the power law Y = AX B described above, respectively. Using Tc, a, and b, the corrosion amount d(t) at a certain time t (t > Tc) is expressed by the following formula (1). d(t)=a×(t - Tc)b ···(1) The corrosion relational expressions are created for the corrosion occurrence life Tc and the corrosion amount d(t) respectively, based on the past corrosion database. The time-dependence is considered for the relational expression of the corrosion amount.

[0022] In the upper part of FIG. 2, i.e., FIG. 2A, a graph showing the relationship between the median values of the corrosion occurrence life Tc of the known sites A and B recorded in the corrosion database (μ Tc,A , μ Tc,B respectively), and the median value of the corrosion amount d(t) according to formula (1) is shown. Graph 100A is the corrosion progress amount graph of site A, and graph 100B is the corrosion progress amount graph of site B. Also, μ Tc,A represents the median value of the corrosion occurrence life Tc of site A, and μ Tc,B represents the median value of the corrosion occurrence life Tc of site B.

[0023] In the lower part of FIG. 2, i.e., FIG. 2B, a graph showing the probability distributions of Tc, a, b of the known sites A and B recorded in the corrosion database and the corrosion amount at time t obs based on formula (1) is shown. Graph 200A is the probability distribution of the corrosion amount of site A, and graph 200B is the probability distribution of the corrosion amount of site B. Here, when the corrosion amount of site A at time t obs is d A,P , the cumulative probability of the corrosion amount d A (t obs ) is calculated using the probability distribution of d A,P . The value giving the same cumulative probability in graph 200B is the corrosion amount d obs of site B at the same time t B,P .

[0024] The relational expression calculation unit 12 formulates the relationship between site A and site B for the corrosion occurrence life Tc and the corrosion amount d(t) respectively, using the addition rule and the multiplication rule.

[0025] 1. Regarding the corrosion amount d(t) Addition rule: d B (t obs ) = d A (t obs ) + K1(t obs ) ···(2) Multiplication rule: d B (t obs ) = K2(t obs ) × d A (t obs ) ···(3)

[0026] 2. Regarding the corrosion occurrence life Tc Addition rule: Tc B = Tc A + K3 ···(4) Multiplication rule: Tc B = K4 × Tc A ···(5)

[0027] Regarding the correction terms K1 to K4, they may be determined as constants deterministically or calculated as a probability distribution. When the correction terms are treated probabilistically, the uncertainty regarding the corrosion relationship of the part is qualitatively set by engineering judgment. The correction terms K1 to K4 may be set considering the differences in properties (material, size, environment) between the ships registered in the corrosion database and the ship H to be evaluated. Note that d B (t obs ) and Tc B values are also calculated as a probability distribution.

[0028] In the case of ships, the values of Tc, a, and b have been analyzed for a number of ships and provided as a known database. The data for parts S and U registered in the corrosion database vary, for example, depending on the ship or even within the same part of the same ship, depending on the actual inspection and measurement locations. However, as illustrated in FIG. 2A, by using the average value or median value, the influence of various corrosion influencing factors (coating, environment) and error factors (inspector skill, measurement error) included in the corrosion database is mitigated. Also, from the distribution characteristics of the entire corrosion database, for example, on the assumption that "in a hull where the upper deck is prone to corrosion, the side shell is also prone to corrosion", the corrosion relationship between parts is defined. It is considered that the probabilistic parameters Tc and a (and in some cases b) calculated on such a premise generally include variations between ships and variations within the same member. By using such a corrosion occurrence life Tc and corrosion progress parameter a to calculate the relational expressions (2) to (5), and further representing the correction terms K1 to K4 by a probability distribution (for example, a normal distribution) as necessary, a relational expression robust to variations can be obtained. The relational expression calculation unit 12 calculates the corrosion occurrence life and progress amount not only for parts A and B but also for all other parts registered in the corrosion database, and formulates the relationship for all combinations of parts.

[0029] The corrosion estimation unit 13 estimates the corrosion state of the evaluation part U by using the measurement data of the measurement part S and the relational expressions (2) to (5) formulated based on the corrosion databases of parts S and U (in the relational expressions exemplified above, the relational expressions when part A corresponds to part S and part B corresponds to part U). For example, the corrosion estimation unit 13 estimates the corrosion occurrence life μ Tc,U of part U by using either or both of the relational expressions (4) and (5). Also, the corrosion estimation unit 13 estimates the corrosion amount d obs of part U at t U (t obs ) by using either or both of the relational expressions (2) and (3). t obs is the time when the corrosion inspection and measurement were performed on the measurement part S.

[0030] Here, the following risks may occur in the measurement data of the measurement site S: (1) The sample size of the inspection measurement is small. (2) There is a bias in the actually measured position, and the target site S is not representative. (3) There is a measurement error due to the environment of the measurement position, the characteristics of the inspection instrument, the ability of the operator, etc. In contrast, the measurement data correction unit 14 may correct the measurement data in order to improve the accuracy of the measurement data of the site S. When it is considered that the accuracy of the measurement site S is not sufficient, the measurement data correction unit 14 fuses and evaluates the past performance (values that can be calculated from the parameters of the corrosion database and actual measurement values) and the measurement data of the measurement site S for the measurement site S by the Bayesian method, thereby correcting the measurement data of the measurement site U. The method of fusion evaluation is described, for example, in the JIP (Joint Industry Project) report "Life Cycle Management of Hull Structure JIP" in 2014. Hereinafter, the method of correcting the measurement data will be described with reference to FIG. 3.

[0031] FIG. 3 shows an example of a corrosion relational model. The model in FIG. 3 represents the corrosion progress parameter a(300) with the probability parameters μ a (301), σ a (302), and further represents the probability parameter μ a (301) with μ μa (311), σ μa (312), and represents the probability parameter σ a (302) with μ σa (313), σ σa (314). Here, the probability parameter μ a (301) of the corrosion progress parameter a(300) is the logarithmic mean of a, and σ a (302) is the logarithmic standard deviation of a. Similarly, μ μa (311) is the logarithmic mean of μ a (301), and σ μa (312) is the logarithmic standard deviation of μ a (301). The same applies to the corrosion occurrence life Tc(320) for μ TcIt is represented by a probability model (not shown) using parameters such as (321). The measurement data correction unit 14 corrects the corrosion amount d of the measurement site S in this correction model S (t)(340), gives the measurement data actually measured at the measurement site S of the ship H to be evaluated, the past performance of other ships at the same site S, and gives the corrosion occurrence life Tc(340) the measurement data actually measured at the measurement site S of the ship H, the past performance of other ships at the same site S. Then, the measurement data correction unit 14 adjusts the values of the above parameters 301 to 302, 311 to 314, 321 by means of the Bayesian inference framework, obtains accurate parameters a and Tc, and according to the above formula (1), obtains d(t)340 at the corrected measurement site S by the fusion evaluation of the past performance and the measurement data.

[0032] Then, the corrosion estimation unit 13 uses the corrected d S (t)(340), the correction term (350), and formulas (4) and (5) to estimate the corrosion amount d of the unmeasured site U u (t)(360).

[0033] The failure probability calculation unit 15 performs a probabilistic prediction of the corrosion state for the evaluation site U estimated by the corrosion estimation unit 13 by means of general uncertainty progression calculation. The failure probability calculation unit 15 predicts the corrosion state after 1 year, 2 years, ···, 10 years, ··· while changing the probability parameters, and calculates the probability (failure probability) that the corrosion amount after X years reaches the corrosion amount that can be regarded as a failure.

[0034] The storage unit 16 stores a corrosion database in which measurement data related to the corrosion of various ships, the corrosion occurrence life Tc, and the corrosion progression parameters a and b are registered. The output unit 17 outputs information such as the corrosion occurrence life Tc, the corrosion amount d(t), and the failure probability estimated for the evaluation site U to a display device or an electronic file.

[0035] (Operation of the corrosion estimation device) Next, the flow of the corrosion estimation process for the unmeasured part will be described. FIG. 4 is a flowchart showing an example of the corrosion estimation process for the unmeasured part according to the embodiment. First, the relational expression calculation unit 12 calculates the relational expressions between the respective parts (step S1). The relational expression calculation unit 12 calculates the corrosion relational expressions (2) to (5) based on Tc, a, and b registered in the corrosion database. The relational expression calculation unit 12 records the calculated relational expressions in the storage unit 16. Next, the evaluation part to be evaluated is set (step S2). For example, the user inputs the evaluation part U (for example, the upper deck) of the ship H to the corrosion estimation device 10. The corrosion estimation device 10 acquires the information of the input part U and records it in the storage unit 16. Next, the user inputs the measurement data of the measurement part S to the corrosion estimation device 10. The measurement data acquisition unit 11 acquires the measurement data (presence or absence of corrosion, corrosion amount) of the measurement part S and the information of the measurement part S (for example, the side shell) (step S3), and associates the measurement data with the information of the measurement part S and records it in the storage unit 16.

[0036] Next, the measurement data correction unit 14 determines whether to correct the measurement data of the input measurement part S (step S4). For example, when the reliability of the measurement data of the measurement part S is low (such as the measurement error of the part S measured by a plurality of workers being larger than the threshold value), the user inputs to the corrosion estimation device 10 that the reliability of the measurement data is low. When information indicating low reliability is input, the measurement data correction unit 14 determines to correct the measurement data of the ship H, and when information indicating high reliability is input, the measurement data correction unit 14 determines not to correct the measurement data. When it is determined not to correct the measurement data (step S4; No), the process proceeds to the process of step S6.

[0037] When it is determined to correct the measurement data (step S4; Yes), the measurement data correction unit 14 corrects the measurement data (step S5). As described with reference to FIG. 3, the measurement data correction unit 14 probabilistically calculates parameters such as μa from the measurement data and the actual values for the corrosion amount dt(t) modeled using parameters such as a, Tc, and μa. Then, the measurement data correction unit 14 calculates the corrosion amount dt(t), which is the corrected measurement data, using the calculated parameters. S (t) S (t).

[0038] Next, the corrosion estimation unit 13 calculates the relational expression between the evaluation site and the measurement site from among the relational expressions created in step S1 (step S6). The corrosion estimation unit 13 reads out the relational expressions (2) to (5) for calculating the corrosion state from site S to site U from the storage unit 16. Next, the corrosion estimation unit 13 estimates the corrosion situation of the evaluation site based on the measurement data and the relational expressions (step S7). The corrosion estimation unit 13 estimates the corrosion occurrence life μ TcU of the evaluation site U by using the measurement data or the corrected measurement data and the relational expression (4) based on the addition rule. Further, the corrosion estimation unit 13 estimates the corrosion occurrence life μ TcU of the evaluation site U based on the measurement data or the corrected measurement data and the relational expression (5) based on the multiplication rule. Similarly, the corrosion estimation unit 13 calculates two estimated values for the corrosion amount dt U (t) of the evaluation site U based on the measurement data or the corrected measurement data, and the relational expressions (1) and (2). The corrosion estimation unit 13 records the calculated estimated values of the corrosion state of the evaluation site U in the storage unit 16. Although all the estimated values estimated by the addition rule and the subtraction rule can be used as indicating the corrosion state of site U, for example, among the four estimated values (however, each estimated value is probabilistically represented), if the value is extremely large compared to site S, it is also possible not to use this estimated value. For example, when the corrosion amount of site U is larger than that of site S by a predetermined number or more (for example, 100 times or more), the corrosion estimation unit 13 may add flag information indicating that it cannot be used as an estimated value and record it in the storage unit 16 on the grounds that this value is likely to be an inaccurate estimate.

[0039] Next, the failure probability calculation unit 15 predicts the future failure probability due to corrosion (step S8). Referring to FIG. 6. For example, the failure probability calculation unit 15 calculates the future corrosion amount based on d s (t) calculated by varying the parameter a (300) and the parameter Tc (320) within a predetermined range for the corrosion amount du(t) (360) of the evaluation site U in FIG. 6. For example, the failure probability calculation unit 15 sets the values a1 and Tc1 for the parameters a (300) and Tc (320) respectively, and calculates the corrosion amount d S (t) every year from 1 year later to 20 years later, and the corrosion amount d SBased on (t) and relational expressions (1) to (2), the corrosion amount d U (t) is calculated. The failure probability calculation unit 15 records the corrosion amount d U (t) for each year. The failure probability calculation unit 15 performs this calculation, for example, thousands to tens of thousands of times while changing the values of the parameters a(300) and Tc(320). For example, when 10,000 combinations of the parameters a(300) and Tc(320) are tried, and the number of times the corrosion amount d U (t = 10 years) exceeds the threshold value is 5,000 times, the failure probability calculation unit 15 calculates the failure probability of part U after 10 years as 50%. Note that for the method of varying the parameters, for example, for the parameter μ a , the MAP (maximum a posteriori) estimation using the value at which the posterior distribution is maximum is applied to perform the calculation of the progress of uncertainty (the same applies to other parameters), and the method of double Monte Carlo trials in which the parameter μ μa and σ μa are used to vary the parameter μ a by the Monte Carlo method can be considered.

[0040] Next, the output unit 17 outputs the estimated value of the corrosion of part U estimated in step S7, the failure probability estimated in step S8, etc. (step S9). The corrosion estimation device 10 executes the process shown in FIG. 4 for the locations where the inspection and measurement of the corrosion of the ship H cannot be carried out, and performs the estimation of the corrosion state and the calculation of the future failure probability. As a result, the corrosion state is estimated for all parts of the ship H (some are actually measured), and the future failure probability is calculated for all parts. The user checks the corrosion state based on the output information and creates a maintenance plan to prevent failures due to corrosion. Next, the creation of a maintenance plan for dealing with corrosion will be described.

[0041] (Configuration of the maintenance planning device) The maintenance planning device 20 includes a corrosion data acquisition unit 21, a maintenance menu acquisition unit 22, a plan creation unit 23, a storage unit 24, and an output unit 25. The corrosion data acquisition unit 21 acquires information such as the corrosion occurrence life Tc, the corrosion amount d(t), and the failure probability of each part calculated by the corrosion estimation device 10. The maintenance menu acquisition unit 22 acquires information on the maintenance menu for each part. The plan creation unit 23 creates a maintenance plan for each part and a maintenance plan for the entire structure (ship H) to be evaluated. The storage unit 24 stores information necessary for the maintenance plan. The output unit 25 outputs the created maintenance plan.

[0042] (Operation) The creation process of the maintenance plan will be described with reference to FIG. 6. FIG. 6 is a flowchart showing an example of the creation process of the maintenance plan according to the embodiment. First, the user inputs evaluation conditions for creating a maintenance plan, such as the reliability for the entire object to be evaluated, the reliability for each part, the expected value of the cost for each part, and what to prioritize in creating the maintenance plan (for example, a maintenance plan with a reliability of a predetermined value or more and a minimum total cost), into the maintenance plan device 20. The maintenance plan device 20 acquires the input evaluation conditions and records them in the storage unit 24 (step S11).

[0043] Next, the corrosion data acquisition unit 21 acquires the failure probability data of each part from the corrosion estimation device 10 and records it in the storage unit 24 (step S12). Next, the maintenance menu acquisition unit 22 acquires information on the maintenance menu for each part (step S13). For example, the maintenance menu includes a method of preventive maintenance of part 1 of the ship H by method 1 (maintenance menu 1), a method of preventive maintenance of part 1 by method 2 (maintenance menu 2),..., a method of maintenance by method 3 for dealing with the state where the thinning of part 1 has progressed (maintenance menu 3),..., a method of dealing with the case where a failure due to corrosion has occurred in part 1 by method 4 (including replacement parts and spare parts) (maintenance menu 4), and so on. The maintenance menu acquisition unit 22 also acquires various maintenance menus for other parts 2, 3,.... Further, the maintenance menu acquisition unit 22 acquires information on the preventive maintenance cost required when each maintenance menu of each part is implemented (the cost incurred only for the implementation of the maintenance menu), the degree of improvement in reliability, and the total cost (the cost for dealing with failures in addition to the implementation cost of the maintenance menu). The maintenance menu acquisition unit 22 records the acquired information in the storage unit 24.

[0044] Next, the plan creation unit 23 sets a maintenance plan for each part (step S14). The plan creation unit 23 calculates a combination of maintenance menus that suppress the total cost (or preventive maintenance cost) while satisfying the desired reliability for each part. For example, for a predetermined evaluation period, for the period until the corrosion occurrence life (e.g., average value) of the target part, the above-described maintenance menu 1 for preventive maintenance is implemented once a year, and after that, the maintenance menu 3 is implemented once a year. When the failure probability reaches a predetermined value or more, a maintenance plan 1 that implements the maintenance menu 4, a maintenance plan 2 that implements the maintenance menu 1 once every two years and the maintenance menu 3 once every two years, and so on. The plan creation unit 23 also calculates the total implementation cost of the maintenance menus included in the formulated maintenance plan. In addition, the plan creation unit 23 has an evaluation model for calculating the reliability when the maintenance menus included in each of the maintenance plans 1, 2,... are implemented. By this evaluation model, the reliability (e.g., average reliability) of the part during the evaluation period when each maintenance plan is implemented is calculated. Further, the plan creation unit 23 calculates, for example, the cost for coping with failures during the evaluation period by multiplying the failure probability during the evaluation period indicated by the failure probability data by the cost required when part 1 fails due to corrosion. The plan creation unit 23 calculates the total cost by adding the cost for coping with failures and the total preventive maintenance implementation cost. An example of the relationship between a plurality of maintenance plans for a certain part created in this way, the relationship between the total cost and reliability when the maintenance plan is implemented, and the relationship between the preventive maintenance cost and reliability is shown in FIG. 5. One circle mark in FIG. 5 indicates the relationship between the total cost and reliability when one maintenance plan is implemented. The plan creation unit 23 performs regression analysis on the points of the circle marks to calculate a regression equation L1 showing the relationship between the total cost and reliability of the maintenance for the part. For example, when the user desires a maintenance plan for the part that has a reliability of a certain standard C1 or more and the lowest total cost, the plan creation unit 23 selects the maintenance plan corresponding to a certain circle mark (e.g., P1) and calculates its total cost and reliability. If the reliability of the selected maintenance plan is C1 or more and the total cost is below the target value, the maintenance menu corresponding to the selected circle mark is temporarily set as the maintenance menu for the part.Alternatively, if there is a maintenance plan that meets the reliability criterion C1 or higher and has a lower total cost based on the regression equation L1, the planning unit 23 may select those maintenance plans (P2, P3).

[0045] One cross mark in FIG. 5 indicates the relationship between the preventive maintenance cost and the reliability when one maintenance plan is implemented. The planning unit 23 performs a regression analysis on the cross-mark points to calculate a regression equation L2 showing the relationship between the preventive maintenance cost and the reliability at that part. For example, when the user desires a maintenance plan that meets a certain reliability criterion C1 or higher and has the lowest preventive maintenance cost, the planning unit 23 selects a maintenance plan that meets the conditions from among the cross marks and tentatively sets it as the maintenance plan for that part. The planning unit 23 performs the same process for all parts, and tentatively sets a part-specific maintenance plan that meets the reliability criterion and has a cost (total cost or preventive maintenance cost) equal to or lower than the target value for each part.

[0046] Next, the planning unit 23 combines the maintenance menus provisionally set for all parts to create and evaluate an overall maintenance plan (step S15). The planning unit 23 calculates the total cost (or preventive maintenance cost) of the overall maintenance plan by summing up the total costs (or preventive maintenance costs) of the maintenance plans provisionally set for each part. Also, the planning unit 23 calculates the overall reliability by calculating the product of the reliabilities of the maintenance menus provisionally set for each part. Based on the overall total cost (or preventive maintenance cost) and the overall reliability, the planning unit 23 performs overall optimization of the maintenance plan. For example, for each of parts 1 to N, the planning unit 23 calculates the sensitivity of reliability (for example, when the total cost is increased by X yen for each of parts 1 to N and the corresponding maintenance menu is implemented, the degree of increase in the overall reliability), and for parts with high reliability, allocates a larger total cost (or preventive maintenance cost) and re-sets the maintenance plan for that part. The planning unit 23 performs this sensitivity evaluation for all parts. For parts with a high sensitivity of reliability, the planning unit 23 shifts in the direction of increasing the total cost (or preventive maintenance cost), and for parts with a low sensitivity of reliability, either maintains the status quo or shifts in the direction of reducing the total cost, and re-evaluates the overall reliability and the total cost (or preventive maintenance cost). The planning unit 23 repeats the adjustment of the maintenance plan for each part and the re-calculation of the overall total cost (or preventive maintenance cost) and the overall reliability until the overall total cost (or preventive maintenance cost) and the overall reliability meet the evaluation conditions (step S16). The planning unit 23 calculates the combination of the maintenance plans for each part when the overall total cost (or preventive maintenance cost) and the overall reliability meet the conditions of the desired reliability and total cost as the final overall maintenance plan. The output unit 25 outputs the final maintenance plan to a display device or the like (step S17).

[0047] (Effect) As described above, according to the corrosion estimation device 10, it is possible to predict the corrosion occurrence life and the amount of corrosion of other parts from the measurement data of the corrosion of a certain part. Thereby, it is possible to estimate the corrosion state without performing corrosion inspection and measurement on all parts such as large structures. Also, it is possible to estimate the corrosion state even for parts where it is impossible to install sensors or the like for detecting the corrosion state. Further, according to the corrosion estimation device 10, as the corrosion state of the unmeasured part, the corrosion occurrence life Tc and the amount of corrosion d(t) are predicted as a probability distribution in consideration of various variations, so that the reliability thereof can be grasped together with the predicted value of the corrosion state. Also, even when there is doubt about the reliability of the measurement data of the measurement part in the evaluation target, by correcting the measurement data, it is possible to predict the member thinning state in consideration of the unreliability of the inspection (inspection bias and measurement error). Furthermore, based on the corrosion relational expressions (2) to (5) generated from the measurement data and the corrosion database, it is possible to quantify the future amount of corrosion, the failure occurrence probability, and the corrosion criteria exceedance probability. Thereby, risk management of the operation of the evaluation target becomes possible. For example, by using the failure probability, it is possible to estimate the failure risk due to the corrosion of a specific part of interest and establish a reasonable maintenance plan. Also, for the entire evaluation target, it is possible to establish a maintenance plan that balances reliability and cost.

[0048] FIG. 7 is a diagram showing an example of the hardware configuration of the corrosion management system according to the embodiment. The computer 900 includes a CPU 901, a main storage device 902, an auxiliary storage device 903, an input / output interface 904, and a communication interface 905, and is connected to the sensor 800. The above corrosion management system 1 is implemented in a computer 900. Each of the functions described above is stored in an auxiliary storage device 903 in the form of a program. The CPU 901 reads the program from the auxiliary storage device 903, expands it in the main storage device 902, and executes the above processing according to the program. Further, the CPU 901 secures a storage area in the main storage device 902 according to the program. Also, the CPU 901 secures a storage area in the auxiliary storage device 903 for storing data being processed according to the program. The measured value measured by the sensor 800 is input to the computer 900 through the input / output interface 904 or the communication interface 905, and is stored in the auxiliary storage device 903 by the processing of the CPU 901.

[0049] Note that a program for realizing all or part of the functions of the corrosion management system 1 may be recorded on a computer-readable recording medium, the program recorded on this recording medium may be read into a computer system and executed, thereby performing the processing by each functional unit. Here, the "computer system" is assumed to include hardware such as an OS and peripheral devices. Also, the "computer system" includes a homepage providing environment (or display environment) if the WWW system is being used. Also, the "computer-readable recording medium" refers to a portable medium such as a CD, DVD, USB, or a storage device such as a hard disk built into a computer system. Also, when this program is distributed to the computer 900 via a communication line, the receiving computer 900 may expand the program in the main storage device 902 and execute the above processing. Also, the above program may be for realizing a part of the functions described above, or may further be realizable in combination with a program already recorded in the computer system for the functions described above.

[0050] As described above, although some embodiments according to the present disclosure have been described, all of these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, as well as in the invention described in the claims and the equivalent scope thereof.

[0051] <Supplementary Note> The corrosion management system, estimation method, and program described in the embodiments are understood as follows, for example.

[0052] (1) The corrosion management system 1 according to the first aspect includes a measurement data acquisition unit 11 that acquires measurement data indicating the corrosion state at a first part (part S) of a structure (ship H) to be evaluated, and relational expressions (2) to (5) between the corrosion state at the first part of the evaluation target and the corrosion state at a second part (part U), and a corrosion estimation unit 13 that estimates the corrosion state (corrosion occurrence life, corrosion amount) at the second part based on the relational expressions and the measurement data at the first part. Thereby, the corrosion state of the unmeasured part can be estimated.

[0053] (2) The corrosion management system 1 according to the second aspect is the corrosion management system of (1), and further includes a relational expression calculation unit 12 that calculates the relational expression based on parameters (Tc, a, b registered in the corrosion database) analyzed from the measurement data of the first part and the second part in another structure (another ship registered in the corrosion database) different from the structure. The relational expressions (2) to (5) can be calculated from the measurement data of the first part and the second part in another structure.

[0054] (3) The corrosion management system 1 according to the third aspect is the corrosion management system 1 of (2), wherein the parameter is the corrosion occurrence life Tc, and the prediction formula of the corrosion progress amount when Y is the corrosion amount and X is the time is Y = AXB They are A and B in For many structures, these values are published. The relational expressions can be calculated using the published values.

[0055] (4) The corrosion management system 1 according to the fourth aspect is the corrosion management system 1 of (1) to (3), further comprising a measurement data correction unit that corrects the measurement data of the first part based on the measurement data and the measurement data measured at the first part of other past structures. Thereby, even when there is uncertainty about the reliability of the measurement data of the first part, the reliability of the measurement data can be ensured, and the accuracy of the estimated value of the corrosion state of the second part can be guaranteed.

[0056] (5) The corrosion management system 1 according to the fifth aspect is the corrosion management system 1 of (1) to (4), wherein the relational expression is a relational expression based on an addition rule indicating that the amount indicating the corrosion state at the second part is equal to the amount obtained by adding a correction amount to the amount indicating the corrosion state at the first part, and a relational expression based on a multiplication rule indicating that the amount indicating the corrosion state at the second part is equal to the amount obtained by multiplying the amount indicating the corrosion state at the first part by a correction amount, or both. By formulating both the relational expression based on the addition rule and the relational expression based on the multiplication rule, even when there is a problem with the estimation accuracy of one relational expression, the corrosion state of the unmeasured part can be estimated by the other relational expression.

[0057] (6) The corrosion management system 1 according to the sixth aspect is the corrosion management system of (1) to (5), wherein the relational expression includes a first relational expression indicating the relationship between the corrosion occurrence life of the first part and the corrosion occurrence life of the second part, and a second relational expression indicating the relationship between the corrosion progress amount of the first part and the corrosion progress amount of the second part. Thereby, as the corrosion state of the second part, the corrosion occurrence life and the corrosion extension amount can be estimated (corrosion two-stage model).

[0058] (7) The corrosion management system 1 according to the seventh aspect is the corrosion management system of (1) to (6), and further includes a failure probability calculation unit that predicts the probability that the progress amount of corrosion at the second part exceeds a threshold value according to the second relational expression. By calculating the failure probability due to corrosion, a maintenance plan for corrosion can be considered.

[0059] (8) The corrosion management system 1 according to the eighth aspect is the corrosion management system of (1) to (7), and further includes a plan creation unit 23 that creates a first maintenance plan for the corrosion of the first part and a second maintenance plan for the corrosion of the second part based on the corrosion states of the first part and the second part. A maintenance plan according to the corrosion situation can be created for each part.

[0060] (9) The corrosion management system 1 according to the ninth aspect is the corrosion management system 1 of (8), and the plan creation unit calculates a first cost related to the first maintenance plan and a first reliability that is the reliability of the first part achieved by the first maintenance plan, calculates a second cost related to the second maintenance plan and a second reliability that is the reliability of the second part achieved by the second maintenance plan, calculates a third cost and a third reliability related to a third maintenance plan created for all parts other than the first part and the second part that the evaluation target has, calculates a total cost that is the sum of the first cost, the second cost, and the third cost, and an overall reliability that is the product of the first reliability, the second reliability, and the third reliability, and adjusts at least one of the first maintenance plan, the second maintenance plan, and the third maintenance plan so that either or both of the total cost and the overall reliability satisfy a predetermined standard. Thereby, while corresponding to the corrosion of each part, an overall optimized maintenance plan can be created.

[0061] (10) In the estimation method according to the tenth aspect, there are steps of obtaining measurement data indicating the corrosion state of the first part of the structure to be evaluated, and estimating the corrosion state of the second part based on the relational expression between the corrosion state of the first part and the corrosion state of the second part of the structure to be evaluated and the measurement data of the first part.

[0062] (11) The program according to the eleventh aspect causes the computer 900 to execute steps of obtaining measurement data indicating the corrosion state of the first part of the structure to be evaluated, and estimating the corrosion state of the second part based on the relational expression between the corrosion state of the first part and the corrosion state of the second part of the structure to be evaluated and the measurement data of the first part.

Explanation of Reference Numerals

[0063] 1 ··· Corrosion management system 10 ··· Corrosion estimation device 11 ··· Measurement data acquisition unit 12 ··· Relational expression calculation unit 13 ··· Corrosion estimation unit 14 ··· Measurement data correction unit 15 ··· Failure probability calculation unit 16 ··· Storage unit 17 ··· Output unit 20 ··· Maintenance planning device 21 ··· Corrosion data acquisition unit 22 ··· Maintenance menu acquisition unit 23 ··· Planning creation unit 24 ··· Storage unit 25 ··· Output unit 900 ··· Computer 901 ··· CPU 902 ··· Main memory device 903 ··· Auxiliary storage device 904 ··· Input / output interface 905 ··· Communication interface

Claims

1. a measurement data acquisition unit that acquires measurement data indicative of a state of corrosion in a first portion of a structure to be evaluated; a corrosion estimation unit that estimates a state of corrosion in the second portion based on a relational equation between a state of corrosion in the first portion of the evaluation target and a state of corrosion in a second portion and the measurement data of the first portion; Equipped with the relational expressions include a first relational expression indicating a relationship between a corrosion initiation lifespan for the first portion and a corrosion initiation lifespan for the second portion, and a second relational expression indicating a relationship between an amount of progress of corrosion in the first portion and an amount of progress of corrosion in the second portion. Corrosion Management Systems.

2. a relational equation calculation unit that calculates the relational equation based on parameters analyzed from the measurement data of the first portion and the second portion of another structure different from the structure; The corrosion management system of claim 1 further comprising:

3. The parameters are the corrosion initiation life Tc and the prediction formula for the amount of corrosion progression when Y is the amount of corrosion and X is time: Y=AX Ｂ A and B in The corrosion management system of claim 2.

4. a measurement data correction unit that corrects the measurement data of the first portion based on the measurement data and measurement data previously measured at the first portion of another of the structures; The corrosion management system according to claim 1 , further comprising:

5. the relational expression is either or both of a relational expression based on an addition rule indicating that the amount indicating the state of corrosion at the second portion is equal to an amount obtained by adding a correction amount to the amount indicating the state of corrosion at the first portion, and a relational expression based on a multiplication rule indicating that the amount indicating the state of corrosion at the second portion is equal to an amount obtained by multiplying the amount indicating the state of corrosion at the first portion by a correction amount. The corrosion management system according to any one of claims 1 to 4.

6. a failure probability calculation unit that predicts a probability that an amount of progress of corrosion in the second portion will exceed a threshold value using the second relational expression; The corrosion management system according to claim 1 , further comprising:

7. 7. The corrosion management system according to claim 1, further comprising a plan creation unit that creates a first maintenance plan for corrosion of the first part and a second maintenance plan for corrosion of the second part based on the corrosion state of the first part and the second part.

8. the plan creation unit calculates a first cost related to the first maintenance plan and a first reliability which is the reliability of the first part achieved by the first maintenance plan, calculates a second cost related to the second maintenance plan and a second reliability which is the reliability of the second part achieved by the second maintenance plan, calculates a third cost and a third reliability related to a third maintenance plan created for all parts other than the first part and the second part of the evaluation target, calculates a total cost which is the sum of the first cost and the third cost, and an overall reliability which is the product of the first reliability, the second reliability, and the third reliability, and adjusts at least one of the first maintenance plan, the second maintenance plan, and the third maintenance plan so that either or both of the total cost and the overall reliability satisfy a predetermined criterion. The corrosion management system of claim 7.

9. acquiring measurement data indicative of a state of corrosion in a first portion of a structure to be evaluated; estimating a state of corrosion in the second portion based on a relational equation between a state of corrosion in the first portion of the evaluation target and a state of corrosion in a second portion and the measurement data of the first portion; having the relational expressions include a first relational expression indicating a relationship between a corrosion initiation lifespan for the first portion and a corrosion initiation lifespan for the second portion, and a second relational expression indicating a relationship between an amount of progress of corrosion in the first portion and an amount of progress of corrosion in the second portion. Estimation method.

10. On the computer, acquiring measurement data indicative of a state of corrosion in a first portion of a structure to be evaluated; estimating a state of corrosion in the second portion based on a relational equation between a state of corrosion in the first portion of the evaluation target and a state of corrosion in a second portion and the measurement data of the first portion; having a process in which the relational expression includes a first relational expression showing a relationship between a corrosion initiation lifespan for the first portion and a corrosion initiation lifespan for the second portion, and a second relational expression showing a relationship between an amount of progress of corrosion in the first portion and an amount of progress of corrosion in the second portion; A program that executes the following.

Images