A method for calculating the critical value of KPI indicators for evaluating FPSO risk level

Abstract

The present invention discloses a method for calculating the critical value of a KPI indicator for evaluating the risk level of an FPSO, comprising the following steps: S1, establishing a 3×3 safety level matrix; S2, determining the corrosion rate in the yth year as a KPI indicator; S3, exploratory solution of the theoretical value of the remaining plate thickness; S4, determination of the critical value of the KPI indicator; S5, performing corrosion detection as planned based on ultrasonic technology; S6, regular review and update. Scientifically selecting KPI indicators and accurately determining their critical values ​​can better analyze risk conditions. Effective evaluation based on the basic indicators themselves solves the shortcoming of traditional methods that only focus on the overall risk assessment of the system; using ultrasonic detection technology to perform efficient and accurate visual detection and evaluation of the corrosion rate and corrosion level of the FPSO can not only improve the management efficiency of the FPSO, but also focus on high-risk components and repair them, thereby reasonably extending the life of the ship and ensuring the safe operation of the ship.

Description

Technical Field

[0001] The present invention relates to the technical field of ship risk assessment, and in particular to a method for calculating a critical value of a KPI indicator for assessing the risk level of an FPSO. Background Art

[0002] During their service, ships are subject to numerous factors, leading to performance degradation and, in turn, to a gradual deviation from their design values. Therefore, studying hull structural safety performance indicators is crucial for the long-term, stable service of ships. Key Performance Indicators (KPIs) are extracted from numerous indicators and used for key monitoring, cost optimization, and hull risk analysis. KPIs are effective metrics that reflect the safety level of hull structures and reflect key performance parameters. Engineers and managers can use KPI monitoring data to assess the reliability of the hull.

[0003] Corrosion is an unavoidable and significant factor affecting the safety rating of ships in service. FPSOs are subject to both internal and external corrosion throughout their service life. When corrosion accumulates to a certain level, the hull can suffer serious safety incidents due to a reduction in the ultimate structural strength, resulting in significant economic losses. Therefore, by considering and measuring uncertain influencing factors such as corrosion damage, a KPI indicator for assessing the FPSO risk level and calculating its critical value is proposed, which is of great significance for the safe operation of the hull throughout its lifecycle.

[0004] The indicators used to regularly assess the hull risk level mainly include performance indicators (PIs) and key performance indicators (KPIs). KPI indicators are selected from PI indicators and have a greater impact on the safety performance of the hull structure. KPI indicators should be reviewed more frequently than PIs. There are many factors that cause FPSO hull structure failure, and many aspects need to be monitored. Corrosion damage to ships during service is inevitable, and the corrosion damage of FPSOs is relatively complex. KPI indicators used in existing studies to assess FPSO risk levels are difficult to obtain in actual engineering or cannot fully reflect the corrosion damage status of FPSO structures. The parameter that can most accurately evaluate the corrosion damage status of hull structures is corrosion rate. The critical value of KPI indicators is generally determined by experimental research or based on engineers' experience, which is not accurate or too conservative. To this end, a method for calculating the critical value of KPI indicators for assessing FPSO risk levels is proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for calculating the critical value of KPI indicators for evaluating the risk level of FPSO. In view of the advantages and disadvantages of traditional methods, on the basis of the original theory, the present invention develops a KPI indicator for evaluating the risk level of FPSO by considering and measuring the uncertain influence of corrosion damage, and studies the calculation method of its critical value, and compares it with ultrasonic detection data to provide a basis for evaluating the risk level of FPSO, so as to solve the problems raised in the above background technology.

[0006] To achieve the above purpose, the present invention provides the following technical solution: A method for calculating the critical value of KPI indicators for evaluating the risk level of FPSO, including the following steps:

[0007] S1. Establish a 3×3 safety level matrix;

[0008] S2. Determine the corrosion rate in the yth year as the KPI indicator;

[0009] S3. Exploratory solution of the theoretical value of the remaining plate thickness;

[0010] S4. Determination of the critical value of the KPI indicator;

[0011] S5. Conduct corrosion detection according to the plan based on ultrasonic technology;

[0012] S6. Regularly review and update.

[0013] Preferably, in S1, the method for establishing a 3×3 safety level matrix is as follows: <正确的标签应是0000068,按照要求保留

[0014] Establish a 3×3 safety level matrix of FPSO with the corrosion failure consequence level of FPSO as the abscissa and the reliability index β as the ordinate;

[0015] Classify the reliability index level and failure consequence.

[0016] Preferably, use β to represent the reliability index level, and the reliability index β = β(y) decreases year by year. The level classification is as follows:

[0017] When 0 < β ≤ 1.0, it is reliability level 1;

[0018] When 1.0 < β ≤ 3.0, it is reliability level 2;

[0019] When β ≥ 3.0, it is reliability level 3.

[0020] [[ID= Preferably, use cof to represent the failure consequence. The level classification is as follows:

[0021] When 0mms < cof ≤ 0.1mms, it is failure consequence level 1;

[0022] When 0.1 mms < cof ≤ 1 mms, it is the failure consequence level 2;

[0023] When cof ≥ 1 mms, it is the failure consequence level 3;

[0024] where mms: million US dollars.

[0025] Preferably, the exploratory solution of the theoretical value of the remaining plate thickness is as follows:

[0026] Taking the total number of plates of the FPSO as N, where the number of plates vulnerable to corrosion is M, t m is the initial thickness of M plates, and the remaining plate thickness in the yth year of service:

[0027]

[0028] where y is the service life, is the corrosion rate of the mth plate in the yth year, is the remaining plate thickness in the ith year of service;

[0029] Taking as the KPI index.

[0030] [[ID=三十二]]Preferably, the calculation method of the critical value of the KPI index:

[0031] Taking Z as the function function and classifying the reliability of the hull structure according to the value of the function function Z, specifically as follows:

[0032] When Z > 0, it means that the hull structure is reliable;

[0033] When Z < 0, it means that the hull structure is unreliable and is in a failure state;

[0034] When Z = 0, it means that the hull structure is in a limit state;

[0035] where the limit state equation:

[0036] Z = R - S = R(E, σ S ) - S(M s , M w ) = R(E, t′ m,y,th ) - (aM s + M w ) = 0

[0037] In the formula, the ultimate strength R of the hull structure, the elastic modulus E of the material, the yield limit σ S , the plate thickness t′ m,y,th , the load variable S, the hydrostatic moment M s , the wave moment M w ; both R and S are random variables;

[0038] Among them, the ultimate strength R of the hull structure and the elastic modulus E and yield strength σ of the material S The yield strength is related to the plate thickness t′ m,y,th The load S is the hydrostatic bending moment M s and wave bending moment M w The superposition of still water bending moment and wave load is calculated by Turkstra criterion S(M s ,M w )=aM s +M w , a is the combination coefficient;

[0039] The reliability index is the mean ratio of the performance function Z to the standard deviation, that is:

[0040]

[0041] Therefore, the theoretical design value of the remaining plate thickness in the yth year of service is tentatively calculated based on its corresponding relationship with the design value of the reliability design index in the yth year β(y), and then the random variable t′ is obtained. m,y,th The mean of

[0042] When the actual value of the remaining plate thickness in the yth year of service minus the theoretical design value of the remaining plate thickness in the yth year of service is equal to 0, the obtained value is That is the critical value of the KPI indicator corrosion rate in the yth year of service;

[0043] Among them, the calculation formula for the critical value of the KPI indicator corrosion rate in the yth year of service is:

[0044]

[0045] When the critical value is exceeded, the above formula is less than zero, the actual remaining plate thickness is less than the theoretical remaining plate thickness, and the hull structure is unreliable.

[0046] Preferably, in S5, ultrasonic detection technology is combined to regularly conduct efficient and accurate visual detection and evaluation of the corrosion rate and corrosion level of the FPSO, thereby obtaining the corrosion status of the FPSO; the detection data is compared with the critical values ​​of the above-mentioned KPI indicators, and then the reliability of the FPSO is evaluated.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] (1) Scientifically select KPI indicators and accurately determine their critical values ​​to better analyze risk conditions. This solves the problem that the critical values ​​of KPI indicators are generally determined by engineers' experience, which is inaccurate or too conservative. Effective evaluation is carried out based on the basic indicators themselves, which solves the shortcomings of traditional methods that only focus on the overall risk assessment of the system. This allows for clear and targeted management of enterprise risk management. Accurately and timely grasp the technical status of FPSOs, and scientifically detect and analyze potential problems.

[0049] (2) Risk assessment of KPI indicators can be performed within a specified time period and represented in the security level matrix, enabling dynamic monitoring. This allows for a clear observation of the security level area in which KPI indicators are located within a specified time period, while also clarifying the overall risk value of a system, enabling risk management focused on system risk and guided by indicator risk.

[0050] (3) Reduce inspection time and optimize inspection costs. Focus on detecting corrosion conditions, reduce unnecessary inspections, and use ultrasonic inspection technology to conduct efficient and accurate visual inspection and assessment of corrosion rate and corrosion level on FPSOs. This can not only improve the management efficiency of FPSOs, but also focus on high-risk components and repair them, thereby reasonably extending the life of the ship and ensuring its safe operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a schematic diagram of the process of the present invention;

[0052] Figure 2 This is a schematic diagram of the FPSO 3×3 safety level matrix structure of the present invention. DETAILED DESCRIPTION

[0053] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0054] Example

[0055] See also Figure 1 and Figure 2, the present invention provides a technical solution: a method for calculating the critical value of KPI indicators for evaluating the risk level of FPSO. Aiming at the advantages and disadvantages of traditional methods, on the basis of the original theory, the present invention develops a KPI indicator for evaluating the risk level of FPSO by considering and measuring the uncertain influence of corrosion damage, and studies the calculation method of its critical value, and compares it with the ultrasonic test data to provide a basis for evaluating the risk level of FPSO. Specifically as follows:

[0056] I. Establish a 3×3 safety level matrix;

[0057] Taking the corrosion failure consequence level of FPSO as the abscissa and the reliability index β as the ordinate, establish a 3×3 safety level matrix of FPSO. Use β to represent the reliability index level, and the reliability index β = β(y) decreases year by year.

[0058] Use β to represent the reliability index level, and the reliability index β = β(y) decreases year by year. The level classification is as follows:

[0059] When 0 < β ≤ 1.0, it is reliability level 1;

[0060] When 1.0 < β ≤ 3.0, it is reliability level 2; [[ID=1​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​

[0073] The total number of plates in FPSO is N, and the number of plates susceptible to corrosion is M, t m is the initial thickness of M plates, and the remaining thickness in the yth year of service is:

[0074]

[0075] Where y is the length of service, is the corrosion rate of the mth plate in the yth year, t′ m,i is the remaining plate thickness in the i-th year of service. From the above formula, we can see that the plate thickness of FPSO is related to the corrosion rate of the m-th plate in the y-th year. There is a close relationship between the thickness of each plate and the strength of the FPSO. Determined as KPI indicator.

[0076] 3. Determination of the critical value of KPI indicators in year y;

[0077] The design value of the reliability design index in the yth year is β(y) (already available at the time of design). However, due to many external and internal factors, the actual reliability index will deviate from the theoretical design value. The actual reliability index is β′(y)=f(t′ m,y ), which is a function related to the remaining plate thickness in the yth year of service. Actual value of remaining plate thickness:

[0078]

[0079] R represents the ultimate strength of the structure, and S represents the load variable. Both R and S are random variables. When Z>0, the hull structure is reliable; when Z<0, it is unreliable and in a failed state; and when Z=0, the hull structure is in its limit state, which is the limit state equation.

[0080] Z=RS=R(E,σ S )-S(M s ,M w )=R(E,t′ m,y,th )-(aM s +M w )=0

[0081] Among them, the ultimate strength R of the hull structure and the elastic modulus E and yield strength σ of the material S The yield strength is related to the plate thickness t′ m,y,th The load S is the hydrostatic bending moment M s and wave bending moment M w The superposition of still water bending moment and wave load is calculated by Turkstra criterion S(M s ,M w )=aMs +M w , a is the combination coefficient. The reliability index is the mean value of the performance function Z and the standard deviation, that is:

[0082]

[0083] Therefore, the theoretical design value of the remaining plate thickness in the yth year of service can be tentatively calculated based on its corresponding relationship with the design value of the reliability design index in the yth year, β(y), and then the random variable t′ is obtained. m,y,th The mean of .

[0084] When the actual value of the remaining plate thickness in the yth year of service minus the theoretical design value of the remaining plate thickness in the yth year of service is equal to 0, the obtained value is That is the critical value of the KPI indicator corrosion rate in the yth year of service.

[0085]

[0086] When the critical value is exceeded, the above formula is less than zero, the actual remaining plate thickness is less than the theoretical remaining plate thickness, and the hull structure is unreliable.

[0087] 4. Carry out corrosion inspection as planned based on ultrasonic technology;

[0088] Combined with ultrasonic testing technology, we regularly conduct efficient and accurate visual testing and assessment of the corrosion rate and corrosion level of FPSOs to obtain the corrosion status of FPSOs. The test data is compared with the critical values ​​of the above-mentioned KPI indicators to evaluate the reliability of FPSOs.

[0089] 5. Review and update regularly.

[0090] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for calculating the critical value of a KPI indicator for evaluating the risk level of an FPSO, characterized in that: It includes the following steps: S1. Establish a 3×3 safety level matrix; S2. Determine the corrosion rate in the y-th year as the KPI index; S3. Exploratory solution of the theoretical value of the remaining plate thickness; S4. Determination of the critical value of the KPI index; S5. Conduct corrosion detection according to the plan based on ultrasonic technology; S6. Regularly review and update; Where: In S1, the method for establishing a 3×3 safety level matrix is as follows: Taking the FPSO corrosion failure consequence level as the abscissa and the reliability index β as the ordinate, establish a 3×3 FPSO safety level matrix; Classify the reliability index level and failure consequences; Use β to represent the reliability index level, and the reliability index β = β(y) decreases year by year. The level classification is as follows: When 0 < β ≤ 1.0, it is the reliability level 1; When 1.0 < β ≤ 3.0, it is the reliability level 2; When β ≥ 3.0, it is the reliability level 3; Use cof to represent the failure consequence, and the level classification is as follows: When 0mms < cof ≤ 0.1mms, it is the failure consequence level 1; When 0.1mms < cof ≤ 1mms, it is the failure consequence level 2; When cof ≥ 1mms, it is the failure consequence level 3; Where mms: million US dollars; finally, a 3×3 safety level matrix is formed and its reliability is evaluated; The exploratory solution of the theoretical value of the remaining plate thickness is as follows: The total number of plates in FPSO is N, and the number of plates susceptible to corrosion is M, t m is the initial thickness of M plates, and the remaining thickness in the yth year of service is: Where y is the length of service, is the corrosion rate of the mth plate in the yth year, t′ m,i is the remaining plate thickness in the i-th year of service; FPSO plate thickness and corrosion rate of the mth plate in the yth year There is a close relationship between the thickness of each plate and the strength of the FPSO. Determine as KPI indicator; Calculation method of the critical value of the KPI index: Taking Z as the performance function, and classify the hull structure reliability according to the value of the performance function Z, specifically as follows: When Z > 0, it means the hull structure is reliable; When Z < 0, it means the hull structure is unreliable and in a failure state; When Z = 0, it means the hull structure is in a limit state; Among them, the limit state equation: Z=R-S=R(E,σ S )-S(M s ,M w )=R(E,t' m,y,th )-(aM s +M w )=0 Where, the ultimate strength of the hull structure R, the elastic modulus of the material E, and the yield limit σ s , plate thickness t′ m,y,th , load variable S, hydrostatic bending moment M s , wave bending moment M w ; R and S are both random variables; Among them, the ultimate strength R of the hull structure and the elastic modulus E and yield strength σ of the material S The yield strength is related to the plate thickness t' m,y,th The load S is the hydrostatic bending moment M s and wave bending moment M w The superposition of still water bending moment and wave bending moment is calculated by Turkstra criterion S(M s ,M w )=aM s +M w , a is the combination coefficient; The reliability index is the mean-to-standard deviation ratio of the performance function Z, that is: Therefore, the theoretical design value of the remaining plate thickness in the yth year of service is tentatively calculated based on its corresponding relationship with the design value of the reliability design index in the yth year β(y), and then the random variable t′ is obtained. m,y,th The mean of When the actual value of the remaining plate thickness in the yth year of service minus the theoretical design value of the remaining plate thickness in the yth year of service is equal to 0, the obtained value is That is the critical value of the KPI indicator corrosion rate in the yth year of service; Among them, the calculation formula for the critical value of the KPI index corrosion rate in the y-th year of service: When the critical value is exceeded, the above formula is less than zero, the actual remaining plate thickness is less than the theoretical remaining plate thickness, and the hull structure is unreliable.

2. The method for calculating the critical value of a KPI indicator for evaluating the risk level of an FPSO according to claim 1, characterized in that: In S5, combined with ultrasonic detection technology, regularly conduct efficient and accurate visual detection and evaluation of the corrosion rate and corrosion grade of the FPSO, and then obtain the corrosion situation of the FPSO; compare the detection data with the above critical value of the KPI index, and then conduct a reliability assessment of the FPSO.

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