JPH09305218A - Method and device for optimizing preventive maintenance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optimize the long-term preventive maintenance of plants by calculating the reliability and importance of devices and determining the maintenance (inspection and replacement) periods of the respective devices in consideration of the total maintenance cost on the basis of the limits of the total cost and man-hours as to an overlap of the periodic inspection of the plants. SOLUTION: The dates of periodic inspection of the plants and the processes of maintenance (inspection and replacement) of the devices which are scheduled are inputted to a storage device (b) through an input device (a). Further, the limit values of the total cost and man-hours in a certain period are inputted to the storage device (b) in consideration of threshold values of importance by periodic inspection for each plant and an overlap of periodic inspection among plants so as to maintain the devices during the periodic inspection. According to the threshold values of importance and the limits of the total cost and man-hours in the certain period, the maintenance periods of the devices of the respective plants are determined and the maintenance of the equipment is assigned by periodic inspection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention determines a maintenance (inspection / replacement) time for all devices subject to preventive maintenance in a plurality of large-scale plants that require periodic inspections, and establishes a long-term preventive maintenance plan. A method and apparatus for optimizing.

[0002]

2. Description of the Related Art So far, for a single plant,
Quantitative importance of equipment based on fault tree analysis (FTA) and probabilistic safety assessment (PSA) for extraction of equipment subject to preventive maintenance and determination of actual maintenance content in nuclear plants, chemical plants, etc. An evaluation was being attempted. Recently, reliability-oriented maintenance (RCM: Re
Liability-Centered Maintenance) and risk-based inspection guidelines (RBI: Risk Based Inspection), etc. Extraction and maintenance of important maintenance target equipment from the perspective of unreliability (system failure probability) and risk (core damage frequency in nuclear power plants) The concept of content selection has been introduced by the United States, and quantitative equipment importance evaluations have been proposed.

However, for multiple plants,
There was no method or apparatus to optimize long-term preventive maintenance plans, taking into account overlapping timings of regular inspections based on quantitative equipment importance assessments and maintenance cost assessments.

[0004]

When carrying out a periodic inspection of a large-scale plant, if the periodic inspections of a plurality of plants overlap in a certain period, it is easy to fall short of manpower such as an engineer, and necessary for the periodic inspection. Costs will also be concentrated in one period. Therefore, it is desired to equalize the work and cost by allocating maintenance (inspection / replacement) of the equipment when the regular inspections are duplicated to the regular inspections before and after.

It is an object of the present invention to provide a method and apparatus for optimizing the long-term preventive maintenance of multiple plants, taking into account the duplication of regular inspections.

[0006]

In order to achieve the above object, the present invention calculates reliability and importance by FTA for all devices subject to preventive maintenance of a plurality of large-scale plants, and further, a maintenance cost index. By taking into account (expense required for inspection / replacement), periodic inspections of multiple plants overlap, resulting in total cost for a certain period.
Equipment maintenance (inspection / replacement) even when man-hours are limited
Optimize the long-term preventive maintenance plan for multiple plants by allocating to the regular inspection before and after.

According to the above configuration, the equipment to be subjected to preventive maintenance can be extracted by ranking by quantitative importance evaluation based on FTA. Next, a maintenance cost index (expense required for inspection / replacement) is calculated for the extracted equipment. By using the importance (reliability index) and the maintenance cost index, it is possible to calculate the required cost for each regular inspection. Further, when the cost and man-hours for a certain period are limited, the maintenance (inspection / replacement) of the equipment is allocated to the regular inspections before and after, so that the long-term preventive maintenance plan can be optimized. Further, even when there are a plurality of plants, the timing of maintenance (inspection / replacement) of each device can be determined in consideration of the total cost / man-hour limit in consideration of duplication of the periodic inspection.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be specifically described below.

FIG. 1 shows an embodiment of the configuration of a preventive maintenance optimization device according to the present invention. From the input device a, data for FTA calculation such as device failure rate data, device time data, AND / OR gate calculation logic symbols and logic structures (FT diagrams) are input to the arithmetic processing device c.

In the arithmetic processing unit c, FTA is executed,
From the calculated unreliability (system failure probability) or risk (core failure frequency) of each basic event (equipment name, failure mode) and minimal cut set, Criticality importance, Fussell-Vesely importance, Birnbaum importance, Risk Ac
The importance is calculated by the importance evaluation formulas of hievement Worth and Risk Reduction Worth.

The criticality degree represents the probability that the unreliability of the top event will occur due to the occurrence of the target event A,
It can be calculated by the following formula 1.

[0012]

[Equation 1]

The Fussell-Vesely importance indicates the degree of contribution to the unreliability of the peak event of the minimal cut set including the event of interest A, and can be calculated by the following equation 2.

[0014]

[Equation 2]

The Birnbaum importance expresses the influence (difference) on the unreliability of the peak event depending on whether or not the event A of interest occurs, and can be calculated by the following equation 3.

[0016]

## EQU00003 ## Bl _i = P (top | A = 1) -P (top | A = 0) (3) Here, in the Bl _i Birnbaum importance Risk Achievement Worth, the occurrence probability of the focused event A is 1
It represents the increase rate of the unreliability of the peak event in the case of, and can be calculated by the following equation 4.

[0017]

(Equation 4)

The Risk Reduction Worth represents the effect of reducing the unreliability of the peak event when the occurrence probability of the target event A becomes 0, and can be calculated by the following equation 5.

[0019]

(Equation 5)

Next, sort the devices in descending order of importance,
The device name, failure mode, and importance data are sent to the storage device b for storage.

It is assumed that the failure rate data of the equipment has time dependency, and that the order of importance is exchanged every time the periodical inspection is performed due to replacement of the equipment or the like.

Furthermore, maintenance of the extracted equipment,
The maintenance cost index (expense required for inspection / replacement) is input from the inspection data to the storage device b by the input device a. The maintenance cost index is quantified from the labor cost required for inspection or the cost of equipment and parts and labor cost required for replacement.

Next, the data of the device name, the failure mode, and the importance of the device order sort having the high importance (reliability index) stored in the storage device b by the input from the keyboard (mouse) f are retrieved, and the data is stored in the storage device. The maintenance cost index (expense required for inspection / replacement) for each device extracted from b and the device are collated and combined, and the relationship between the importance and the cost is graphed. Here, the abscissa indicates the degree of importance, for example, the rank (rank) of the cumulative risk of the constituent devices is plotted, and the ordinate indicates the maintenance cost index, for example, the cumulative total of the maintenance costs up to that rank is plotted. The graphed data is converted into coordinates for each image to be displayed, the image data is created by the arithmetic processing unit c, and the image data is sent to the CRT control unit g. CR
In the T control device g, the sent image data is processed by a color CRT.
Converted to display signal, e display (color CRT)
To display the image.

When there are a plurality of target plants, the above operation is repeated for each plant. Next, with respect to the schedule of the periodic inspection and the scheduled process of the maintenance (inspection / replacement) of the device, all the scheduled processes are input to the storage device b by the input device a. Also, during regular inspections, equipment maintenance (inspection /
The threshold value of the importance for each regular inspection and the limit value of the total cost / man-hours for performing the replacement) are input to the storage device b.

According to the threshold of the importance and the limitation of the total cost and the number of man-hours, the timing of maintenance (inspection / replacement) of each device is determined, and the maintenance (inspection / replacement) of the device is allocated for each periodic inspection. The plan for long-term periodic inspection can be created.

On the other hand, even when the number of target plants is plural,
Similarly, for each plant, the schedule of periodic inspections,
With regard to the process of maintenance (inspection / replacement) of the equipment, all the planned items are input to the storage device b by the input device a. Also, in order to perform maintenance (inspection / replacement) of equipment during regular inspections, considering the threshold value of the importance of each regular inspection of each plant and the overlapping of the regular inspection timing of multiple plants. Then, the limit value of the total cost / man-hour during a fixed period is input to the storage device b. According to the threshold of this importance and the limit of total cost and man-hours during a certain period, the timing of equipment maintenance (inspection / replacement) of each plant is determined, and equipment maintenance (inspection / replacement) is performed at regular inspections. Allocate to. For example, by selecting plants that have little overlap with other plants in the regular inspections before and after, move the ones of high importance to the previous regular inspection, and those of low importance to the latter regular inspection, thereby The timing of maintenance (inspection / replacement) can be decided. In this way, a long-term periodic inspection plan for multiple plants can be created.

FIG. 2 shows the outline of an embodiment of the processing procedure in the arithmetic processing unit shown in c, and FIGS. 3 to 6 show the details of the embodiment.

In the first step, a keyboard (mouse) is used.
By f, the plant name whose importance is calculated is read into the arithmetic processing unit c.

In the second step, the keyboard (mouse)
Whether or not the FTA calculation is executed is read by f, and if not executed, the process proceeds to the seventh step. Otherwise, go to the third step.

In the third step, the data for executing the FTA calculation is read from the input device a into the arithmetic processing device c.

In the fourth step, the FT is executed by the arithmetic processing unit c.
Perform A calculation.

In the fifth step, the importance is calculated from the calculated unreliability or risk of each basic event and the minimal cut set by the importance evaluation formula, and is sent to the storage device b for storage.

In the sixth step, the keyboard (mouse)
According to f, which of the calculated degrees of importance is to be used is read, and data in which the device name, the failure mode and the degree of importance are set is sent to the arithmetic processing unit c.

Next, the process proceeds to the eighth step.

In the seventh step, the input device a reads the data in which the name of the device to be used, the failure mode and the importance are read and sent to the arithmetic processing device c.

In the eighth step, the arithmetic processing unit c sorts the data in descending order of importance.

In the ninth step, the sorted data including the set of device name, failure mode and importance is sent from the arithmetic processing device c to the storage device b and stored therein.

In the tenth step, the maintenance cost index (expense required for inspection / replacement) for the equipment extracted by the input device a is read into the arithmetic processing device c.

In the eleventh step, the maintenance cost index for the equipment is sent from the arithmetic processing unit c to the storage device b and stored therein.

In the twelfth step, whether or not a correlation graph of the degree of importance and the maintenance cost index is created is read by the keyboard (mouse) f, and if not created, the process proceeds to the sixteenth step.

Otherwise, proceed to step 13.

In the 13th step, the coordinates of the graph to be set are read into the arithmetic unit c by the keyboard (mouse) f.

In the fourteenth step, the arithmetic processing unit c graphs the rank of the importance of the equipment and the cumulative maintenance cost up to that rank, and sends the data to the printer d for output.

In the fifteenth step, the image data is sent from the arithmetic processing unit c to the CRT control unit g, the signal is converted and the image is displayed on the display (CRT) e.

In the 16th step, the schedule of the periodic inspection and the process data of the maintenance (inspection / replacement) of the equipment are read into the arithmetic processing unit c from the input unit a and sent to the storage unit b for storage. In the 17th step, 1-1 for other plants
A keyboard (mouse) f is used to input whether or not to execute the 6-step process. If the process is to be executed, the process proceeds to the first step.

In the 18th step, the name of the plant for which the regular inspection process is to be created by the keyboard (mouse) f (s)
Is read into the arithmetic processing unit c.

In the nineteenth step, the threshold value of the importance level for executing the maintenance (inspection / replacement) of the equipment and the limit value of the total cost / man-hours are read into the arithmetic processing unit c by the keyboard (mouse) f.

In the twentieth step, the arithmetic processing unit c creates a long-term process (primary) of a plurality of periodic inspections according to the threshold value of the importance.

In the twenty-first step, the keyboard (mouse) f is used to read into the arithmetic processing unit c whether or not the total cost / man-hours of the periodic inspection is limited. If there is no limit, the process proceeds to the twenty-third step.

In the 22nd step, the arithmetic processing unit c allocates maintenance (inspection / replacement) of equipment to regular inspections before and after according to the limitation of total cost and man-hour for each plant.
Create a long-term process (secondary) for multiple periodic inspections.

In the 23rd step, in the arithmetic processing unit c,
It is determined whether the number of plants is plural, and if the number of plants is one, the process proceeds to the 27th step.

Otherwise, proceed to the 24th step.

In the 24th step, the keyboard (mouse) f is used to read into the arithmetic processing unit c whether or not there is a limit on the total cost / man-hours during a certain period. If there is no limit, the process proceeds to the 27th step.

Otherwise, proceed to the 25th step.

In the twenty-fifth step, the arithmetic processing unit c selects the plant having the least overlap in the regular inspections before and after the plurality of plants in a certain period when the total cost and man-hours are limited.

In the twenty-sixth step, the arithmetic processing unit c performs equipment maintenance (inspection / checking) on the selected plant.
(Replacement) is allocated to the regular inspections before and after according to the limitation of total cost and man-hours, and a long-term process (third stage) of multiple periodic inspections is created.

In the 27th step, the created long-term process data of a plurality of regular inspections is sent from the arithmetic processing unit c to the storage unit b and stored therein.

In the 28th step, the plant name for outputting the maintenance contents of the long-term process of the periodic inspection is read into the arithmetic processing unit c by the keyboard (mouse) f.

In the 29th step, the long-term process data of the periodic inspection of the plant output from the storage device b is read into the arithmetic processing device c, and the maintenance plan is sent to the printer d and output.

In the 30th step, the image data is sent from the arithmetic processing unit c to the CRT control unit g, the signal is converted and the image is displayed on the display (CRT) e.

In the 31st step, whether or not the processing is to be executed for the other plant is read from the keyboard (mouse) f into the arithmetic processing unit c, and if it is executed, the 28th step is executed.
Return to step.

Otherwise, the process ends.

Next, in the present invention, the method of determining the maintenance (inspection / replacement) process of the equipment when the periods of the periodic inspections of the three plants overlap will be described in detail with reference to steps 18 to 26 of FIG. An example is shown. The three plants are A, B, and C, and as shown in FIG.
It is assumed that an overlap of 3 plants occurs in the mth periodic inspection of the B plant and the nth periodic inspection of the C plant. Considering the relationship between the time t and the cost and man-hours required for maintenance (inspection / replacement) of equipment, as shown in Fig. 4, the cost and man-hours increase when the periodic inspections of three plants overlap. Is expected. For this reason, avoiding concentration of costs and man-hours for a period of time, processing for leveling is performed, and the time for maintenance (inspection / replacement) of equipment is determined.

In the 18th step, the plant names of the three plants (A, B, C) for which the periodic inspection process is to be created are read.

In the 19th step, for each plant,
Read the threshold value of the importance of performing equipment maintenance (inspection / replacement) in the periodic inspection and the total cost / man-hour limit value in the periodic inspection. The degree of importance depends on the magnitude of the impact of equipment failure on plant operation, the years of use and life of the equipment, and if the threshold of importance is high, the cost and man-hours can be small, but the threshold is If it is low, the cost and man-hour will be large.

Here, as the threshold value of importance, it is possible to set a different value for each number of periodic inspections.

In the twentieth step, a long-term process for the periodic inspection of three plants is created according to the threshold value of importance.
The maintenance (inspection / replacement) of the equipment in the periodical inspection is carried out from the most important one, and the boundary of whether or not to carry out is the threshold of this importance. The schedule for multiple regular inspections is entered in advance, and the long-term plan for equipment inspection / replacement is determined from the threshold value of importance. here,
A plant's (k-1), k, (k + 1) times, B plant's (m-1), m, (m + 1) times, C plant's (n-1), n, (n + 1) times. Decide the maintenance content to be implemented in the periodic inspection of. This is the long-term process of the first regular inspection.

In the 21st step, it is judged whether or not the total cost / man-hours of the periodical inspection are limited. If there is no restriction, the process proceeds to the 23rd step.

In the twenty-second step, for each plant, if there is a limit to the total cost / man-hours of the specific number of regular inspections, the maintenance (inspection / replacement) of the equipment is allocated to the regular inspections before and after.

As the total cost / man-hour, the cost / man-hour required for the maintenance (inspection / replacement) of the equipment in the periodic inspection is calculated from the threshold of the importance and the maintenance cost index. There is no problem if the calculated total cost and man-hours are smaller than the limit values.

In the 23rd step, the number of plants is 3, and there are a plurality of plants.

In the twenty-fourth step, it is judged whether or not there is a limit on the total cost / man-hours within a fixed period. If there is no limit, the process proceeds to a twenty-seventh step.

In the twenty-fifth step, it is checked whether or not the regular inspection before and after the target regular inspection for each plant has an overlap with the regular inspection with other plants, and the priority is given in order from the plant with the least overlap. decide.

In this case, it is assumed that the kth inspection of the A plant, the mth inspection of the B plant, and the nth inspection of the C plant are duplicated in a certain period in which the total cost and man-hours are limited. A plant (k-1), (k + 1) times,
Examining the (m-1), (m + 1) th periodic inspection of the B plant and the (n-1), (n + 1) th periodic inspection of the C plant,
A plant (k-1) th, B plant (m +)
1) Since the regular inspections do not overlap with other plants, the priority is high.

In the twenty-sixth step, the threshold value of the importance of the equipment is set to be strict in the order of the plant with the highest priority, and the maintenance (inspection / replacement) of the equipment is allocated to the regular inspection before and after. Here, as shown in FIG. 4, among the kth maintenance (inspection / replacement) of the A plant, the most important one is the (k-1) th maintenance of the B plant and the mth maintenance of the equipment ( By assigning the less important ones of (inspection / replacement) to the (m + 1) th time, it is possible to avoid concentration of maintenance work for a certain period and smooth it. The thresholds of importance are set to be strict by carrying out those with high importance in the previous regular inspection and those with low importance in the latter regular inspection. If the (k-1) th periodical inspection of the A plant has already been completed, it is allocated only to the (m + 1) th periodical inspection of the B plant.

As a result, the total value of the total cost and man-hours of the three plants for a certain period is set so as not to exceed the limit value.

From the above results, an example of the maintenance work plan in the regular inspection output in the 29th step is as shown in FIG. Here, the contents of the maintenance work in the mth periodical inspection of the B plant are output. The list displays the system name, device name, site, maintenance work, and importance in order of importance. Since the threshold value of importance which was 0.009 when the first process was created was increased to 0.01, the (m +
1) Maintenance work has been postponed to the periodic inspection.

[0078]

Since the present invention is constructed as described above, it has the following effects.

(1) The reliability index of risk, unreliability, occurrence frequency, and importance of each device is calculated for all devices subject to preventive maintenance in a plurality of large-scale plants. High equipment can be extracted.

(2) The extracted important devices are ranked (sorted in descending order of importance), and the expenses required for maintenance (inspection / replacement) of each component device are collectively displayed as a maintenance cost index. By doing so, the correlation between equipment importance and maintenance cost can be clarified.

(3) According to the above item (2), it is possible to determine the time of maintenance (inspection / replacement) of each device in a large-scale plant and optimize a long-term preventive maintenance plan.

(4) In the above item (3), when there are restrictions on the cost and man-hours of the regular inspection for a certain period, considering the duplication of the periodic inspection, the total cost, the man-hour, etc. are limited. By allocating maintenance (inspection / replacement) of equipment to regular inspections before and after, it is possible to optimize the long-term preventive maintenance plan.

(5) Further, even if the number of plants is one, by allocating maintenance (inspection / replacement) of equipment to regular inspections before and after, it is possible to optimize a long-term preventive maintenance plan.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a flowchart of a processing procedure by the arithmetic processing unit in the configuration of the embodiment of the present invention.

FIG. 3 is a flowchart of a processing procedure by the arithmetic processing unit in the configuration of the embodiment of the present invention.

FIG. 4 is a flowchart of a processing procedure by the arithmetic processing unit according to the embodiment of the present invention.

FIG. 5 is a flowchart of a processing procedure by the arithmetic processing unit according to the embodiment of the present invention.

FIG. 6 is a flowchart of a processing procedure by the arithmetic processing unit according to the embodiment of the present invention.

FIG. 7 shows the maintenance (inspection /
FIG.

FIG. 8 is an explanatory diagram of a maintenance work plan in a periodic inspection output according to an embodiment of the present invention.

[Explanation of symbols]

a ... input device, b ... storage device, c ... arithmetic processing device, d ...
Output device, e ... Display, f ... Keyboard, g ... C
RT controller.

Claims (8)

[Claims] 1. When carrying out regular inspections at a plurality of plants, fault tree analysis is performed on all of the devices subject to preventive maintenance of the respective plants by means of fault tree analysis, the reliability of the devices in the device, the system or the plant, and the importance of the devices. The preventive maintenance optimization is characterized by calculating the degree of maintenance, considering the maintenance cost, and determining the maintenance time of each equipment from the limitation of total cost and man-hours against duplication of periodic inspections of multiple plants. Method. 2. The preventive maintenance optimization method according to claim 1, wherein a long-term plan for a plurality of periodic inspections is created. 3. The preventive maintenance optimization method according to claim 2, wherein the number of plants can be processed not only in the case of plural plants but also in the case of one plant, and the timing of maintenance of each equipment is determined. 4. When carrying out a periodical inspection at a plurality of plants, a fault tree analysis is performed on all the devices subject to preventive maintenance in each plant,
Calculating the reliability and importance of the equipment in the system or plant, considering the maintenance cost, and deciding the maintenance time for each equipment from the limitation of total cost and man-hours against the duplication of periodic inspections of multiple plants A preventive maintenance optimization device characterized by: 5. The preventive maintenance optimization device according to claim 4, which creates a long-term plan for a plurality of periodic inspections. 6. The preventive maintenance plan optimizing device according to claim 5, wherein the number of plants can be processed not only in the case of a plurality of plants but also in the case of one plant, and determines the maintenance time of each equipment. 7. The preventive maintenance optimizing device according to claim 5, which has a function of storing the determined importance, maintenance cost index, and maintenance plan data in a regular inspection. 8. The preventive maintenance optimization device according to claim 7, which has a function of outputting a maintenance plan in the determined periodic inspection.