JP2009205554A - Method for calculating degree of deterioration of equipment, and risk assessment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a deterioration degree calculation method that computes a more accurate degree of deterioration and makes use of experience such as past maintenance. <P>SOLUTION: The method for calculating the degree of deterioration of equipment comprises dividing an elapsed time from the start of operation of equipment into a plurality of periods, computing in advance a transition of the degree of deterioration of each model of equipment in each divided period from past degrees of deterioration, and computing a degree of deterioration of a piece of equipment subjected to maintenance examination for the cumulative operation time thereof from the piece of equipment subjected to maintenance examination and the cumulative operation time according to the transitions of the degree of deterioration computed in advance. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for determining the degree of deterioration of equipment and a risk evaluation method.

  In recent years, various facilities have been increased in size, and if the equipment constituting the facilities is damaged, it is often the case that large damage is caused. For this reason, inspection and maintenance (maintenance) of equipment are indispensable in order to maintain equipment soundly.

  Many methods for efficiently and economically maintaining equipment have been proposed. In particular, in recent years, a maintenance method called RBM (Risk Based Maintenance) method has attracted attention and has been implemented. This RBM is designed to minimize the product (risk) of the probability of equipment damage, that is, the degree of deterioration, and the magnitude of damage taking into account human damage and economic damage when the equipment is damaged. Maintenance is performed. That is, when the damage is caused to each equipment that constitutes the equipment, the likelihood of damage (degree of degradation) is classified into four ranks (for example, high, medium, low, and fine). Are classified into a plurality of ranks (for example, four ranks of serious, large, medium, and small). Then, as shown in FIG. 8, a risk rank diagram is created with the vertical axis representing the likelihood of damage and the horizontal axis representing the magnitude of the damage. The risk value is evaluated by plotting the product value obtained in (1). This figure shows that the risk is greater as the product value is plotted above or to the right of the figure.

  Furthermore, the magnitude of the risk is classified into a plurality of categories (for example, categories I, II, III, and IV), and measures for each category are determined in advance. For example, category I is acceptable and can be used as it is, and does not require inspections or inspections other than predetermined inspections. Category II is conditionally acceptable and can be used if it is properly inspected and maintained. Category III is a plan change requiring measures to reduce damage. Category IV is not permitted, and parts are replaced or repaired so that they are immediately below Category II.

By adopting such a maintenance method based on RBM, it is said that efficient, economical and appropriate maintenance is possible.
Conventionally, when performing maintenance based on RBM, risk is evaluated by the procedure shown in FIG. 9 or FIG. FIG. 9 shows a case where the degree of deterioration of the device is obtained without being based on actual data, and FIG. 10 is a case where the degree of deterioration of the device is obtained based on actual data.

  In the case of FIG. 9, first, the operator activates a risk evaluation apparatus including a computer (not shown). Then, as shown in step 10, the operator selects the name and model of the risk assessment target equipment constituting the thermal power plant or nuclear power plant, and inputs them using an input device such as a keyboard. To do. When the device name, model, etc. are input, the risk evaluation device searches the plant database (plant DB) 30.

  The plant DB 30 constitutes a part of the risk evaluation apparatus, and includes a recording medium such as a hard disk, a flexible disk, and an optical disk. The plant DB 30 includes an existing equipment DB unit 32, a damage magnitude DB unit 34, and a failure DB unit 36. In the existing equipment DB unit 321, names and models of equipment constituting the plant are registered. Further, the damage magnitude DB unit 34 is registered with the magnitude of the amount corresponding to the expected damage such as the amount when the plant stops operation and the amount of parts to be replaced. As described in Patent Document 1, the failure DB unit 36 registers the probability distribution of the usage time until the device that is obtained for each device is damaged.

  When a risk evaluation target device is selected, the risk evaluation device searches the existing device DB unit 32 of the plant DB 30 to extract the corresponding device and display it on the display unit. The operator confirms the device name and model displayed on the display unit and decides to perform risk assessment for RBM (step 12). Next, the operator must determine the magnitude of damage when the equipment for which risk assessment has been determined is damaged (for example, the number of days of plant shutdown when the equipment is damaged, the number of personnel required for repair and restoration) And the name and number of parts to be replaced) (step 14). When the damage magnitude is input, the risk evaluation device refers to the damage magnitude DB unit 34 of the plant DB 30 and calculates the amount of damage magnitude (step 16).

  On the other hand, the operator inputs the magnitude of damage as in step 14 and causes the risk evaluation apparatus to calculate the degree of equipment deterioration (probability of equipment damage) as in step 18. To do. In the damage occurrence probability calculation process 18, the operator first inputs the cumulative usage time of the target device (step 20). When the accumulated usage time of the device is input, the risk evaluation device refers to the failure DB unit 36 of the plant DB 30 and displays the current degree of deterioration (probability of damage) of the device to be subjected to risk evaluation in%. .

  When the risk evaluation apparatus finds the damage occurrence probability of the risk evaluation target device and the amount of damage magnitude, it calculates the risk of obtaining the product of both. (Step 24). Then, the risk evaluation apparatus displays the evaluation for the risk obtained for the risk evaluation target device, that is, where the obtained damage amount and the damage occurrence probability are located in FIG. 8 and belongs to which category. Based on the displayed risk evaluation, the operator determines a maintenance method for the risk evaluation target device by a maintenance plan database (not shown).

  In the case of FIG. 10, the maintenance plan is created as follows. The risk evaluation method shown in FIG. 10 differs from the case of FIG. 9 in the method of obtaining the damage occurrence probability of the risk evaluation target device. The damage occurrence probability calculation process 18 in FIG. When the target device is determined, the risk evaluation apparatus searches the inspection DB unit 36a of the plant DB 30a, refers to the inspection data of the same type of device as the target device (step 40), and calculates the damage occurrence probability (step). 42). When the risk evaluation device obtains the damage occurrence probability of the device, it performs risk evaluation in the same manner as described above (step 26).

In the inspection DB section 36a of the plant DB 30a, as described in Patent Documents 2 and 3, along with the device design data, the number of operating days of the device, the damage mode, the frequency of occurrence of damage, inspection data, and maintenance data Etc. are registered for each device.
JP 2003-345423 A JP 2005-122525 A JP 2005-182465 A

  By the way, the degree of deterioration of a device greatly depends on design conditions such as the material of the device and use conditions (environment). For example, deterioration of equipment depends on whether the usage environment of the target equipment is a harsh environment such as a dusty, hot and humid environment, an environment where corrosive gas exists, or a good environment such as a clean room. It is known that the lifespan differs greatly. And, as in Patent Document 1, when determining the degree of deterioration of a device from the probability distribution of the usage time until the device is damaged, the design conditions and use conditions (environment) of the target device, the presence or absence of maintenance, etc. I do not consider anything. For this reason, detailed maintenance according to the equipment here cannot be performed, and efficient and economical maintenance cannot be performed.

  In addition, as described in Patent Documents 2 and 3, the method for obtaining the degree of deterioration by reflecting the inspection result takes into consideration the design conditions and use conditions of the equipment, so that maintenance appropriate to the equipment model and the like is required. It becomes possible. However, the methods described in Patent Documents 2 and 3 obtain the degree of deterioration of the equipment based on the inspection results throughout the entire period from the start of use of the equipment. However, equipment does not cause damage with a uniform probability throughout the entire period of use. It is known that the degree of deterioration of a device generally increases as the period of use increases, while the degree of deterioration decreases when appropriate maintenance is performed. Therefore, it is difficult to perform more appropriate maintenance on the devices here in the degradation degree calculation methods described in Patent Documents 2 and 3.

The present invention has been made in order to eliminate the above-described drawbacks of the prior art, and aims to make it possible to obtain a more accurate degree of deterioration.
Another object of the present invention is to make use of experience such as maintenance performed in the past.
Furthermore, an object of the present invention is to enable more accurate risk evaluation and more appropriate maintenance of each device.

In order to achieve the above object, the device deterioration degree prediction method according to the present invention divides the elapsed time from the start of use of the device into a plurality of periods, and determines each device type based on the past deterioration degree data. For each of the divided periods, the transition of the deterioration degree is obtained in advance, and the usage time for the target device is calculated based on the transition of the occurrence rate of damage obtained in advance from the maintenance target device and the usage time thereof. It is characterized in that the degree of deterioration in a period including it is obtained.
In this case, the transition of the deterioration degree obtained in advance includes at least a design condition, a use condition, and a history of the equipment as factors.

  In the device deterioration degree calculation method according to the present invention, for a device of the same type as the device whose risk is to be evaluated, it is determined whether or not deterioration degree data based on a pre-inspected inspection exists, and the deterioration degree data exists. If the degradation degree data is not present, the risk assessment is performed by the device degradation degree calculation method according to claim 1 or 2. The degree of deterioration of the target device can be obtained.

  The risk evaluation method according to the present invention is a risk evaluation method for evaluating a risk based on a product of a degree of deterioration of a device and the magnitude of damage when the device is damaged. Is divided into a plurality of periods, and the transition of the deterioration degree is obtained in advance for each of the divided periods for each type of equipment based on the past deterioration degree, and the equipment to be considered for maintenance and its accumulated usage time Therefore, based on the transition of the degree of deterioration obtained in advance, using the method for calculating the degree of deterioration of the equipment for which the degree of deterioration during the cumulative usage time is obtained for the equipment to be examined for maintenance, the degree of deterioration of the equipment to be examined for maintenance is calculated. It is characterized by seeking.

  In the present invention as described above, the elapsed time from the start of use of the device is divided into a plurality of periods, and the transition of the deterioration degree is obtained for each divided period based on the past deterioration degree data. Based on the transition of the deterioration degree obtained for each period, the deterioration degree in the cumulative usage time of the maintenance examination target device is obtained, so that a more accurate deterioration degree can be obtained.

  It is desirable that the transition of the degree of deterioration of equipment includes at least the design conditions, use conditions, and equipment history of the equipment as factors. The degree of deterioration of the equipment varies greatly depending on the equipment history, such as equipment materials, types of parts, usage conditions (use environment) such as use at high temperature and high humidity, and whether repairs or parts are being replaced. It is possible to obtain a more accurate degree of deterioration reflecting the above.

  In the risk evaluation method, by using the above-mentioned deterioration degree calculation method, the degree of deterioration of the equipment subject to maintenance examination is obtained, so that more accurate risk evaluation based on the more accurate deterioration degree can be performed. Appropriate equipment maintenance is possible.

DESCRIPTION OF EMBODIMENTS Preferred embodiments of a device deterioration degree calculation method and a risk evaluation method according to the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a flowchart of a risk evaluation method according to an embodiment of the present invention. In FIG. 1, the operator first activates a risk evaluation apparatus (not shown). The risk evaluation apparatus is a risk evaluation examination apparatus for performing maintenance based on RBM, and is composed of a personal computer or the like, an input unit such as a keyboard or a mouse, a display unit such as a CRT, a hard disk or a flexible disk, The plant DB 40 is composed of a recording medium such as an optical disk, and software for performing a predetermined process. The plant DB 40 includes an existing equipment DB unit 42, a damage magnitude DB unit 44, an inspection DB unit 46, a deterioration degree changing element influence DB unit 48, a maintenance record DB unit (not shown), and the like. .

  The existing equipment DB unit 42 stores equipment, models, and the like constituting a plant such as a nuclear power plant, a thermal power plant, a semiconductor factory, and a chemical plant. The amount of damage DB unit 44 is used for the amount of damage per day when the plant is shut down, the cost when replacing damaged equipment, and replacement or repair when the equipment constituting the plant is damaged. The amount of damage per prescribed unit, such as the cost per person required, is stored as the amount of damage. The inspection DB unit 46 stores the results (degradation degree for each model) of inspecting (inspecting) the devices constituting the plant. The degradation degree change element influence DB section 48 is used for design conditions such as the material of each device, use environment temperature of the device, use conditions such as the presence of humidity and corrosive gas (use environment), maintenance and repair of the device. Stores the degree of influence (weighting) on the occurrence of damage to the equipment by the deterioration degree changing element related to the likelihood of damage such as presence / absence, repair location and repair status.

  When the operator activates the risk evaluation apparatus, as shown in step 50, the operator inputs the name and model of the risk evaluation target apparatus from the input unit to the risk evaluation apparatus. When the device name and model are input, the risk evaluation device searches the existing device DB unit 42 of the plant DB 40 and displays the corresponding device and model on the display unit (step 52). The operator confirms the device displayed on the display unit and determines that the device is a risk evaluation target device (step 52), and then the expected damage magnitude (plant) when the device is damaged. The number of stop days, the replacement parts of the equipment, the personnel required for repairing the equipment, the scope of damage, equipment, etc.) are input (step 54). When the damage magnitude is input, the risk evaluation apparatus refers to the damage magnitude DB section 44 of the plant DB 40 and obtains an amount of the expected damage magnitude (step 56).

  On the other hand, when the risk evaluation target device is determined in step 52, the risk evaluation device performs a deterioration degree calculation process 58. In the deterioration degree calculation process 58, first, when a risk evaluation target device is determined, the inspection DB unit 46 is searched to determine whether inspection data exists for the same type of device as the device (step). 60). If there is inspection data for the same type of device in the inspection DB unit 46, the inspection data is referred to (step 62), and the degree of deterioration of the risk evaluation target device selected and determined based on the inspection data is obtained (step 64). ). Thereafter, the risk evaluation apparatus plots the amount of damage obtained in step 56 and the degree of deterioration obtained in step 64 in the risk evaluation diagram shown in FIG. 80). If the operator is a person in charge of maintenance, whether or not to perform maintenance on the selected risk assessment target device based on the maintenance database etc. from the position plotted in the displayed evaluation diagram, and maintenance when performing maintenance Decide how. If the operator is not a maintenance person, the displayed evaluation chart is printed and given to the maintenance person. The maintenance person determines a maintenance method and the like in the same manner as described above based on the printed risk evaluation chart.

  If there is no inspection data for the same type of device as the risk evaluation target device as a result of searching the inspection DB unit 46 in step 60, the risk evaluation device displays that fact on the display unit, and the cumulative usage time of the target device Prompt to enter. The operator inputs the cumulative usage time of the risk evaluation target device based on the cumulative usage time input request displayed on the display unit (step 66). Next, the operator determines the evaluation value (each deterioration degree change element of the risk evaluation target device) for the deterioration degree change element (design condition, use condition, device protection state, etc.) of the risk evaluation target device for each input accumulated usage time. A value obtained by evaluating whether the standard change factor is superior or inferior is input (step 68). In the selected risk evaluation target device, for example, when the deterioration degree changing element is a design condition, and a material superior to the standard design is used, a value that reduces the influence on the occurrence of damage is input. The degradation degree changing element evaluation value can be obtained by using a technique such as AHP (Analytic Hierarchy Process).

  Such processing is performed as follows. For example, an optimization process for predicting the degree of deterioration in corrosion of a louver used in an air conditioning system air passage is taken as an example. Assuming three types of louvers A, B, and C, each louver affects the material (design conditions), usage environment, protection status (such as the presence or absence of rust-prevention coating), or other life as a deterioration factor. The event to be performed is read from the existing equipment DB 42 in the plant database. This data is shown in a chart as shown in FIG. For each louver A, B, and C, the material is SUS, the type of galvanized steel, the usage environment is an air supply system or an exhaust system, whether or not it is rust-proofed as a protection state, and other remarks Determine the contents of the elements that contribute to the change in the degree of deterioration, such as the application of the rust paint or the replacement of the filter in the middle.

  Next, a numerical value of 0 to 1 is assigned to an evaluation element that speeds up the deterioration degree change and an evaluation element that slows down the deterioration degree change evaluation element in corrosion. As described above, the element evaluation value is input by using a method such as AHP (Analytic Hierarchy Process), or by inputting a value for evaluating some degree of deterioration and converting it to a value of 0 to 1. Of course, since it is an air conditioning system, quantitative data such as the salinity concentration and the ratio of intake of outside air may be converted into 0 to 1 and input into the element evaluation value. As a specific example, as shown in FIG. 3, since the material is made of galvanized steel plate faster than SUS, the deterioration degree is shortened (short life), so SUS is “0” and galvanized steel plate is “1”. give. In addition, since it is a louver used in an air conditioning system, when it is used in an air supply system that takes in dirty air, it can be said that the environment promotes the degree of deterioration. If there is a filter in the system, an intermediate value “0.5” is given because there is an effect of reducing deterioration. Furthermore, if the anticorrosion treatment is performed, the life is extended, so that “0” is given, and “1” is given when there is no antirust treatment.

  When the cumulative usage time of the risk evaluation target device and the deterioration degree change element evaluation value are input, the risk evaluation apparatus returns to FIG. 1 and refers to the deterioration degree change element influence degree DB section 48 of the plant DB 40. The history of deterioration degree change elements with respect to usage time in a period including the input cumulative usage time is collected. This is shown in FIG. This history takes into account the case where a rust prevention treatment as an element contributing to the deterioration degree change performed in the progress history of the remarks column shown in FIG. 2 and the case where a filter is attached later. In this example, since the louver A was subjected to rust prevention treatment in 2003, the evaluation value of the protection state (= rust prevention coating) in the evaluation element of the louver A is from “1” up to 2002 to after 2003. Is changed to “0”. Further, since a filter is attached to louver B in 2005, the evaluation value is changed to “0.5” after 2005.

  When such a chart is completed, a predicted transition (curve) of the degree of deterioration is obtained (step 70). After that, the risk evaluation device calculates the degree of deterioration at the present time (input cumulative usage time) based on the obtained curve of the degree of deterioration (step 72). If the risk evaluation device obtains the degree of deterioration in step 72, the risk evaluation device proceeds to step 80 and displays the risk for the risk evaluation target device on the risk evaluation diagram.

  Degradation level change factor influence level is analyzed for each model by analyzing the results of past inspections of equipment to determine how change factors (design conditions, use conditions, protection conditions, etc.) affect the occurrence of damage. Ask for. For example, when a certain device is corroded, the degree of influence on corrosion caused by the design conditions such as the material, type of plating, metal thickness, etc. Analyze and change the influence of changing factors into a value between 0.0 and 1.0 for each model. In determining the change factor influence degree, for example, a technique such as AHP is used to make use of abundant experience and knowledge of an inspector or the like.

  The deterioration degree curve calculation in step 70 is performed based on a linear equation indicating a change in the deterioration degree with respect to the accumulated use time for a period including the accumulated use time for each model. That is, for each model, the time from the start of use is divided into a plurality of periods (for example, in units of one year), and the relationship between the usage time and the degree of deterioration is obtained as a linear equation for each period, It is stored in the degree change element DB unit 48. When the cumulative use time of the risk evaluation target device is input, the deterioration degree change factor influence DB unit 48 is searched to obtain a change in the deterioration degree during the period including the input cumulative use time of the device.

In the case of the embodiment, the change in the degree of deterioration during the divided period is obtained as follows. First, based on the report and other information for each device, the basic data and history data are aggregated for each device (louver A, B, C), and as shown in FIGS. Create Next, as illustrated in FIG. 4, an evaluation value history A _Di (t _N ) is obtained for the deterioration degree changing element Di for each device. This deterioration degree change element evaluation value history A _Di (t _N ) is expressed by a numerical value between 0 and 1 with weights of the degree of deterioration (deterioration degree) applied to various symptoms of the device Q. T _N indicates the year of evaluation. In this embodiment, the case where a plant using new equipment was completed and started operation in 2000 was taken as an example.

  Next, in order to predict the degree of deterioration, the longest life and the shortest life of the louver are obtained from other plant results as initial values. For example, the longest life (1 / α) is 7 years, the shortest life (1 / β) is 20 years, and the like. The longest life may be defined as the design life.

Next, the degree of influence of each evaluation element on the change in the degree of deterioration is initially set based on the judgment of an expert. That is, the ratio of the materials, usage environment, and protection state (rust prevention coating) of the louvers A, B, and C that affect the deterioration is tentatively determined. For example, the material influence degree W _D1 = 0.2, the use environment influence degree W _D2 = 0.5, and the antirust coating influence degree W _D3 = 0.3.

  Next, for each louver, the change rate (slope) α of the deterioration level when the change of the evaluation value of the deterioration level with respect to the cumulative usage time is the smallest, and the change rate (slope) of the deterioration level when the change with respect to the cumulative usage time is the largest ) Calculate β. As a result, it can be assumed that the degree of deterioration of the louver changes with an inclination θ between the inclination α and the inclination β with respect to the cumulative usage period. Therefore, the change rate (gradient) θ of the deterioration degree with respect to the accumulated usage time for each louver is obtained.

When obtaining the change rate (gradient) θ of the deterioration degree, first, the degree of influence on the occurrence of damage of each deterioration degree changing element Di is determined. In the embodiment, as described above, the degree of influence W _Di on the occurrence of damage of each deterioration degree changing element Di in the initial stage (at the time of completion of the plant) is differentiated by weighting based on judgment by a skilled person. Can be assumed to be equal, but not limited to this. That is, in the case of the embodiment, the degree of influence W _Di on the deterioration of each deterioration degree changing element in the initial _stage is a fraction of the deterioration degree changing element. For example, when there are three deterioration degree change elements Di “device design conditions”, “apparatus use conditions”, and “apparatus protection states”, the contribution degrees W _Di of these deterioration degree change elements _Di are respectively It can be 1/3. It may be the reciprocal of the number of set influence factors.

として傾きθを求めるようにしている。 Further, the accumulated usage time is divided into a plurality of appropriate periods. For example, the first period is from the start of use to the second year, the second period is from the third year to the fourth year from the start of use, the third period is from the fifth year to the sixth year from the start of use, etc. Divided into a plurality of periods. Of course, it may be set in units of one year. The length and number of this period can be determined as appropriate in consideration of the type of plant, the lifetime, the degree of deterioration, the degree of damage at the time of occurrence of damage, and the like.
Next, a slope representing the rate of change in the degree of deterioration for each divided period is calculated. this is,

The inclination θ is obtained as follows.

The equation for calculating the slope θ is represented by Equation 2 in the case of the embodiment, where T is the length of the period (years). Note that n indicates the number of the divided period.

として求める。この場合、第１期間における傾きθ_０は、最小傾きαと最大傾きβとの間にある。 For example, when the evaluation load value A _Di (t _N ) of the deterioration degree evaluation change factor is as shown in FIG. 4, assuming 2000 as t = 0, the slope θ ₀ of the first period for each louver, that is, the first The slope θ ₀ of the period from _{0 to} t ₁ of the period is

Asking. In this case, the gradient θ ₀ in the first period is between the minimum gradient α and the maximum gradient β.

０〜ｔ_１の期間の長さをＴとすれば、

とおくことができる。したがって、

となる。さらに、第２期間のｔ_１〜ｔ_２における傾きθ_１は、

として求められる。 By using the slope θ ₀ obtained in this way, it is possible to obtain a predicted deterioration level at an arbitrary time within the first period. For example, the predicted value P (t ₁₎ the degree of deterioration of the cycle t ₁ of the first period is an evaluation period of the first time, when the increment of the deterioration degree of the first period (between 0 to t ₁₎ and Delta] p,

If the length of the period 0 to t ₁ is T,

It can be said. Therefore,

It becomes. Furthermore, the slope θ ₁ in the second period from t ₁ to t ₂ is

As required.

と表される。また、第２期間における傾きθ_１は、この第２期間の長さをＴとすると、

として求められる。数式９と数式１０とからΔｐを消去すると、

となる。 Then, the predicted value P _{(t 2)} the degree of degradation of at _{t 2,} when the increase in the degradation of the period _t 1 ~t ₂ and Delta] p, using the predicted value P of the deterioration degree at _{t 1 (t 1)} ,

It is expressed. Further, the inclination θ ₁ in the second period is T, where the length of the second period is T.

As required. When Δp is eliminated from Equation 9 and Equation 10,

It becomes.

ここに、Ｐ（ｔ_ｎ‐１）は時期ｔ_ｎ‐１における予測劣化度であり、Δｐは期間ｔ_ｎ‐１〜ｔ_ｎにおける劣化度の増分である。そして、この第ｎ期間の長さをＴとすると、第ｎ期間の傾きθ_ｎ‐１）は、

として求められ、したがって、予測劣化度曲線が得られる。 Hereinafter, similarly the procedure determining deterioration degree P at t _n is the period of the n period containing the current cumulative usage time (t _n) by the following equation.

Here, the predicted deterioration degree of P _{(t n-1)} is the time _{t n-1, Δp} is the increment of the deterioration degree in the period _{t n-1} ~t _n. If the length of the n-th period is T, the slope of the _n- th period θ _n-1 ) is

Therefore, a predicted deterioration degree curve is obtained.

On the other hand, as shown in FIG. 5, the thickness measurement data is summarized as an index of the degree of deterioration of each louver. In order to unify the wall thickness measurement result of each louver as one index of the degree of deterioration, for example, the following formula is used.

  The above formula becomes “0” in a new state without thinning, and becomes “1” when the measured value of the plate thickness becomes the control limit value. With this calculation formula, the wall thickness data is converted into the degree of deterioration and summarized in a time series history (FIG. 5).

When the predicted deterioration degree and the actual measurement deterioration degree obtained in this way are plotted on the chart, it is as shown in FIG. The louver A is a square, the louver B is a triangle, and the louver C is a circle mark. White is a predicted value P (t _n ), and black is an actually measured value X (t _n ).

Next, the deterioration degree predicting value P (t _n ) obtained by the calculation in this way and the actual deterioration value X (t _n ) actually obtained by inspection are used to determine the deterioration of each deterioration degree changing element. Find the actual impact to give.

を演算する。さらに、Δｕ_ｎの２乗を評価時期ごとに求め、各ルーバについて求めたΔｕ^２を合計したものを目的関数εとする。

そして、劣化度変化要素影響度Ｗ_Ｄｉの値をいろいろ替えて代入し、εの値が最小となるように各劣化度変化要素影響度Ｗ_Ｄｉの値を求め、劣化度変化要素影響度（劣化度変化要素の重み）を最適化する。このようにして、劣化度変化要素影響度Ｗ_ｎを最適化することにより、図７に示したように、劣化度の予測値を実測値に近づけることができる。 First, the difference Delta] u _n between the predicted value P _{(t n)} and measured values X _{(t n).} That is,

Is calculated. Furthermore, obtains the square of Delta] u _n for each evaluation time, the objective function ε a the sum of the Delta] u ² determined for each louver.

Then, the value of the deterioration degree changing element influence degree W _Di is changed and substituted in various ways, and the value of each deterioration degree changing element influence degree W _Di is obtained so that the value of ε is minimized, and the deterioration degree changing element influence degree (deterioration) Optimize the degree-changing element weight). In this manner, by optimizing the deterioration degree changing element influence W _n, as shown in FIG. 7, it can be brought close to the measured value of the predicted value of the deterioration degree.

Thereafter, based on the new deterioration degree change factor influence degree W _Di , the deterioration degree of the next fiscal year is predicted, and by using the predicted deterioration degree, the maintenance of the plant and equipment based on the appropriate and economical RBM is performed. Can be performed.

  As described above, in the present invention for predicting the degree of deterioration of a device, it is possible to predict the degree of deterioration close to the actual deterioration degree for each device, even if the model is the same as in the past.

  That is, conventionally, if the model is the same, the degradation degree slope with respect to the accumulated usage time is obtained from the statistics of the degradation degree for the whole model. For example, conventionally, even if the devices A, B, and C, which are different devices of the same model, are used, a common inclination (a straight line for predicting a change in the degree of deterioration) is obtained for the models. And the future degradation degree was calculated | required using this straight line. For this reason, conventionally, if the model is the same, the same deterioration degree is predicted regardless of the device.

  On the other hand, as described above, according to the present invention, even when the model is the same, the slope of the deterioration degree is calculated in consideration of the condition (deterioration degree change factor) for each device used, and this is calculated. Prediction can be performed while adjusting the degree of influence on deterioration so that the difference between the actual result and the predicted value is small. For this reason, the present invention enables maintenance suitable for the equipment, and can maintain the plant sound and reduce the cost.

It is a flowchart of the risk evaluation method which concerns on embodiment of this invention. It is a data diagram of the louver type and the deterioration degree changing element according to the embodiment. It is the figure which calculated | required the evaluation value of the deterioration degree change element which concerns on embodiment. It is a figure which shows the example of the deterioration degree change element evaluation log | history which concerns on embodiment. It is a figure which shows the measurement history of the deterioration degree of the louver which concerns on embodiment. It is a graph figure of the prediction degradation degree before optimization, and a measurement degradation degree. It is a graph figure of the prediction deterioration degree after optimization, and an actual measurement deterioration degree. It is a figure explaining the risk evaluation method in RBM. It is a flowchart explaining an example of the method of calculating | requiring the conventional risk. It is a flowchart explaining the other example of the method of calculating | requiring the conventional risk.

Explanation of symbols

40... Plant database 42... Existing equipment database 44 44 Damage magnitude database 46 Inspection database 48 Degradation change factor influence database

Claims (4)

The elapsed time from the start of use of the device is divided into multiple periods, the relationship between the use time and the deterioration level is obtained for each period, and the change in the deterioration level from the device to be considered for maintenance and its accumulated use time Seeking
Based on the transition of the degree of deterioration obtained in advance, the degree of deterioration in the accumulated usage time is obtained for the maintenance target device.
A method for calculating the degree of deterioration of equipment. In the method for calculating the degree of deterioration of the device according to claim 1,
The degree of deterioration of the device determined in advance includes at least the design conditions, use conditions, and protection conditions of the devices as factors.
A method for calculating the degree of deterioration of equipment. For equipment of the same type as the equipment to be assessed for risk, determine whether there is deterioration level data based on inspections conducted in advance,
When the deterioration degree data exists, based on the deterioration degree data, obtain the deterioration degree of the risk assessment target device,
When the deterioration degree data does not exist, the deterioration degree of the risk evaluation target device is obtained by the device deterioration degree calculation method according to claim 1 or 2.
A method for calculating the degree of deterioration of equipment. In a risk assessment method for assessing risk based on the degree of degradation of equipment and the magnitude of damage when the equipment is damaged,
Using the method for calculating the degree of deterioration of equipment according to any one of claims 1 to 3, the degree of deterioration of equipment subject to maintenance examination is obtained.
Risk assessment method characterized by this.

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