Urban gas pipeline danger and risk assessment method
By clarifying the correspondence between risks and consequences of urban gas pipelines and combining monitoring equipment for intelligent early warning analysis, the problem of insufficient correspondence between risks and consequences in existing technologies has been solved, achieving standardization and modularization of gas pipeline risk assessment and improving the safety and reliability of pipeline operation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-30
- Publication Date
- 2026-04-07
AI Technical Summary
In existing urban gas pipeline risk assessment methods, there is a lack of one-to-one correspondence between risks and consequences, resulting in inaccurate matching of prevention and control measures, insufficient real-time data collection and accuracy, and affecting the precision of pipeline safety management.
By determining risk tolerance standards, risk level zoning and identification of key control points, identification and screening of key areas, assessment of consequences and severity, risk calculation and monitoring recommendations, and combining monitoring equipment for intelligent early warning analysis, the assessment results are ensured to truly reflect the residual risk of risk points.
It has achieved standardization and modularization of hazard and risk assessment for urban gas pipelines, improved the safety and reliability of pipeline operation, and ensured the validity and independence of assessment results.
Smart Images
Figure CN121810052A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of gas pipeline hazard and risk assessment technology, and particularly to methods for assessing the hazards and risks of urban gas pipelines. Background Technology
[0002] With the continuous advancement of urban development, urban gas pipelines, as public facilities, have achieved significant development and continuous progress in network layout, and natural gas has become one of the main energy sources for urban life. However, many urban gas pipelines in service are nearing the end of their design life and entering a stage prone to accidents. Strengthening the management of gas pipeline networks and ensuring the safety of natural gas transmission and distribution have become key priorities for the operation and management of gas companies.
[0003] Currently, the industry generally implements a pipeline integrity management strategy, which involves collecting, integrating, and analyzing gas pipeline network data to pre-assess risks and build a decision management model based on risk assessment.
[0004] Risk assessment is a core component of pipeline integrity management, but its effectiveness depends on the scientific nature of the assessment methods.
[0005] The current field of risk assessment for urban gas pipelines suffers from significant technical deficiencies: existing assessment methods lack a one-to-one correspondence between risks and consequences, leading to a disconnect between risk factors, failure consequences, and prevention and control measures. Specifically:
[0006] The same risk may be vaguely associated with multiple consequences, or multiple risks may be confused and associated with the same consequence, making it impossible for prevention and control measures to accurately match specific risks and consequences.
[0007] Even if measures are taken, the lack of correspondence between the measures and the risks and consequences makes it difficult to effectively reduce risks, and it is impossible to ensure the pertinence and effectiveness of the measures. Ultimately, this leads to distorted residual risk assessments and affects the accuracy of pipeline safety management.
[0008] On the other hand, data collection relies on manual recording or single devices, lacking systematic hardware support, resulting in insufficient real-time data and accuracy, further exacerbating the mismatch between risk and consequences. Even with additional measures, the lack of hardware leads to insufficient dynamic risk monitoring.
[0009] Therefore, how to achieve the effectiveness and independence of protective measures and ensure that the assessment results can truly reflect the residual risk of the risk point has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention
[0010] In view of the above-mentioned deficiencies of the prior art, the present invention provides a method for assessing the hazards and risks of urban gas pipelines. The purpose of this method is to clarify the correspondence between risks and consequences by defining the hazard and risk assessment process for urban gas pipelines, thereby achieving the effectiveness and independence of protective measures and ensuring that the assessment results can truly reflect the residual risk of the risk point.
[0011] To achieve the above objectives, this invention discloses a method for assessing the hazards and risks of urban gas pipelines, comprising the following steps:
[0012] Step 1, determine the risk tolerance standard, specifically:
[0013] Based on existing gas risk datasets, including but not limited to asset ownership, pipeline integrity management requirements parameters, pipeline operating pressure, annual inspection records, and the type and number of surrounding buildings, establish risk tolerance standards.
[0014] Step 2, risk level zoning and identification of key control points, specifically:
[0015] Based on the area under the jurisdiction of the gas company of the pipeline to be evaluated and the pressure level of the pipeline to be evaluated, risk level zoning and key control points are identified.
[0016] Step 3, key area identification and filtering, specifically:
[0017] Determine the scope, triggering causes, and consequences of key areas to prevent duplication and omissions, and ensure that risk assessment is rigorous and realistic;
[0018] Step 4, Consequence and Severity Assessment, specifically:
[0019] Before conducting a hazard and risk assessment, evaluate the severity of the consequences of triggering a risk point.
[0020] The assessment results characterizing the severity of consequences must conform to the description of the risk tolerance standard.
[0021] Step 5, risk calculation, specifically:
[0022] Based on the divided work units and identified hazards, analyze the failure frequency and potential impact of each hazard, and calculate the risk value R for each unit;
[0023] Step 6, Risk Management Recommendations, specifically:
[0024] Based on the determined risk level and grade, different monitoring equipment and quantities are used to monitor key assessment indicators and leakage situations, thereby carrying out risk classification and control.
[0025] Step 7, risk reassessment, specifically:
[0026] Intelligent early warning analysis is conducted based on the monitoring data from the monitoring equipment.
[0027] Preferably, in step 1,
[0028] Establish risk tolerance standards, including:
[0029] Input the aforementioned structured database, data quality report, and external parameters;
[0030] External parameters include HSE system documents, corporate risk appetite level, control responsibility entity coding, industry regulations and standards, and risk tolerance matrix;
[0031] Enterprise risk appetite levels are categorized as Level 1, Level 2, or Level 3.
[0032] When establishing standards, external parameters are first imported through programming to establish a correlation mapping between key indicators of the HSE system, industry standard thresholds and risk tolerance matrix, and the matrix weights are adjusted according to the enterprise's risk appetite level.
[0033] Next, extract the qualified data, screen the core influencing factors including failure frequency and surrounding population density, and calculate the tolerable threshold for each factor. The formula for calculating the tolerable threshold is as follows:
[0034] Tolerable threshold = Basic threshold × (1 + Management model adjustment coefficient - Regulatory update correction coefficient);
[0035] The risk classification rules were finally determined as follows:
[0036] Acceptable risk is defined as follows: the actual value of the impact factor is less than or equal to the threshold, and the matrix is in the "green zone".
[0037] The risks that need to be managed are: actual value > threshold and ≤ 1.5 times the threshold or the matrix is in the "yellow zone";
[0038] High risk is defined as: actual value > 1.5 times the threshold or matrix in the "red zone".
[0039] More preferably, in step 2,
[0040] Based on the area under the jurisdiction of the gas company and the pressure level of the pipeline to be evaluated, the pipeline to be evaluated is divided into several blocks. Each block is identified, and the important control points within each block are identified.
[0041] After identification, all important control points are classified and sorted, and targeted management strategies are determined according to different classifications, and key areas are identified.
[0042] The identified key areas should be classified into different levels according to the severity of the consequences.
[0043] More preferably, in step 3, different scenarios for each risk point are identified one by one according to the key areas.
[0044] The identification is carried out according to the level of key areas. The identification and management of each key area adopts a dynamic management approach. When the corresponding pipeline to be evaluated and its surrounding environment change, the situation that can bring new risks to safety management is re-identified. Multiple causes and corresponding consequences of the same risk point are combined into cause-effect pairs as the scenarios for analyzing the corresponding risk points.
[0045] More preferably, in step 4, the hazardous factors in each work unit are identified. Data such as the maximum working pressure of the gas pipeline, the surrounding environment, population density, inspection frequency, monitoring methods, and the level of nearby medical facilities are collected to comprehensively and accurately identify potential risk consequences and provide a basis for subsequent risk assessment and prevention.
[0046] More preferably, in step 5, the unit risk value R = S × C;
[0047] Where S represents the probability of failure; C represents the consequences of failure;
[0048]
[0049] In the formula: Pᵢ: the probability of the first-level independent event occurring for the i-th triggering consequence, i=1,2,...,n, where n is the total number of first-level independent triggering events;
[0050] ∏ is the chain multiplication operator, representing the product of the probabilities of all first-order independent events "not occurring";
[0051] The probability of each first-level independent event is determined by the joint probability of all its second-level sub-events, calculated as follows:
[0052]
[0053] In the formula:
[0054] Pᵢⱼ: The probability of the j-th sub-event under the i-th primary event Pᵢ, j=1,2,...,mᵢ, where mᵢ is the total number of sub-events under the i-th primary event;
[0055] ∏ is the chain multiplication operator, representing the product of the probabilities of all second-level sub-events "not occurring" under the same first-level event;
[0056] The probability of each secondary sub-event is determined by its initial event probability and the risk reduction parameters of the accompanying independent protection measures, calculated as follows:
[0057]
[0058] In the formula:
[0059] : The parameter of the kth independent influencing factor under the i-th primary event and the j-th secondary sub-event Pᵢⱼ, k=1,2,...,tᵢⱼ, where tᵢⱼ is the total number of independent influencing factors under the i-th primary event and the j-th secondary sub-event;
[0060] ∏ is the chain multiplication operator, representing the product of parameters of all independent influencing factors under the same second-level sub-event;
[0061] each Specific definition:
[0062] Xᵢⱼ1: The initial event probability of triggering the secondary sub-event Pᵢⱼ, i.e., the baseline probability of this sub-event occurring without any protective measures;
[0063] Xᵢⱼ2 to Xᵢⱼ t The independent protection measures for mitigation of this secondary sub-event are each set of parameters based on the actual mitigation capability of the corresponding protection measure, and all protection measure parameters are independent of each other and do not interfere with each other.
[0064] The formula for calculating C is as follows:
[0065] in:
[0066] As an indicator The severity weight of the failure consequences;
[0067] The score for the severity of the failure consequences; The range is from 1 to 6.
[0068] More preferably, in step 6, the corresponding tolerable level is determined by assessing the consequences and severity levels of the selected risk point, and the risk value of the consequences of the selected risk point is obtained through the risk calculation in step 5, and compared with the tolerable level:
[0069] If the calculated risk value is less than the tolerable risk value, then the selected risk point is considered acceptable, and the assessment of the danger and risk of the next risk point continues.
[0070] If the calculated risk value is greater than the tolerable risk value, measures to meet the acceptable risk value will be formulated based on the conclusions and recommendations of key area identification, risk assessment, detection, monitoring and evaluation, etc., to set up multiple monitoring points covering the core area of the risk source, along the possible diffusion path and surrounding sensitive areas, forming a three-dimensional monitoring network and targeted risk reduction measures to ensure pipeline safety and risk control, so as to reduce the risk to a tolerable level.
[0071] More preferably, in step 7, the real-time monitoring data is compared and analyzed with historical data and preset safety thresholds to automatically identify potential risks and hazards, and to issue early warning signals according to the severity of the risks. Taking into account factors such as the level of the early warning signal, the trend of risk development, and the effectiveness of the control measures already taken, the risk level is re-determined, and steps 5 to 7 are executed again.
[0072] The beneficial effects of this invention are:
[0073] This invention makes the assessment of hazards and risks of urban gas pipelines more standardized and modular, thereby improving the safety and reliability of urban gas pipeline operation.
[0074] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description
[0075] Figure 1 A flowchart of an embodiment of the present invention is shown.
[0076] Figure 2 An embodiment of the present invention is shown. , , , , and The value of . Detailed Implementation
[0077] Example: Figure 1 As shown, the method for assessing the hazards and risks of urban gas pipelines includes the following steps:
[0078] Step 1, determine the risk tolerance standard, specifically:
[0079] Based on existing gas risk datasets, including but not limited to asset ownership, pipeline integrity management requirements parameters, pipeline operating pressure, annual inspection records, and the type and number of surrounding buildings, establish risk tolerance standards.
[0080] Step 2, risk level zoning and identification of key control points, specifically:
[0081] Based on the area under the jurisdiction of the gas company of the pipeline to be evaluated and the pressure level of the pipeline to be evaluated, risk level zoning and key control points are identified.
[0082] Step 3, key area identification and filtering, specifically:
[0083] Determine the scope, triggering causes, and consequences of key areas to prevent duplication and omissions, and ensure that risk assessment is rigorous and realistic;
[0084] Step 4, Consequence and Severity Assessment, specifically:
[0085] Before conducting a hazard and risk assessment, evaluate the severity of the consequences of triggering a risk point.
[0086] The assessment results characterizing the severity of consequences must conform to the description of the risk tolerance standard.
[0087] Step 5, risk calculation, specifically:
[0088] Based on the divided work units and identified hazards, analyze the failure frequency and potential impact of each hazard, and calculate the risk value R for each unit;
[0089] Step 6, Risk Management Recommendations, specifically:
[0090] Based on the determined risk level and grade, different monitoring equipment and quantities are used to monitor key assessment indicators and leakage situations, thereby carrying out risk classification and control.
[0091] Step 7, risk reassessment, specifically:
[0092] Intelligent early warning analysis is conducted based on the monitoring data from the monitoring equipment.
[0093] This invention ensures that hazard and risk assessment activities for urban gas pipelines are carried out thoroughly and systematically through the above steps. In practical applications, it can fully integrate the transportation process, HSE system documents, management models, and equipment operation data of urban gas pipelines to form a set of hazard and risk assessment procedures suitable for urban gas pipelines.
[0094] This invention systematically implements pipeline risk management and optimizes existing business operation models, aiming to fill the gap in the practical application of existing risk assessment model research results and provide new ideas and references for the safety management of urban gas pipeline networks.
[0095] This embodiment is based on a pre-collected and processed dataset of gas risk samples. This dataset focuses on buried gas pipelines in a certain city from 2020 to 2024. Key data items include: asset ownership, pipeline integrity management requirements, pipeline operating pressure, historical inspection records, and the type and number of surrounding buildings. This data originates from the city's gas company's safety management records and publicly available urban planning maps. Those skilled in the art will understand that when assessing other objects, similar, readily available data should be substituted.
[0096] In step 1,
[0097] Establish risk tolerance standards, including:
[0098] Input the aforementioned structured database, data quality report, and external parameters;
[0099] External parameters include HSE system documents, corporate risk appetite level, control responsibility entity coding, industry regulations and standards, and risk tolerance matrix;
[0100] Enterprise risk appetite levels are categorized as Level 1, Level 2, or Level 3.
[0101] When establishing standards, external parameters are first imported through programming to establish a correlation mapping between key indicators of the HSE system, industry standard thresholds and risk tolerance matrix, and the matrix weights are adjusted according to the enterprise's risk appetite level.
[0102] Next, extract the qualified data, screen the core influencing factors including failure frequency and surrounding population density, and calculate the tolerable threshold for each factor. The formula for calculating the tolerable threshold is as follows:
[0103] Tolerable threshold = Basic threshold × (1 + Management model adjustment coefficient - Regulatory update correction coefficient);
[0104] The risk classification rules were finally determined as follows:
[0105] Acceptable risk is defined as follows: the actual value of the impact factor is less than or equal to the threshold, and the matrix is in the "green zone".
[0106] The risks that need to be managed are: actual value > threshold and ≤ 1.5 times the threshold or the matrix is in the "yellow zone";
[0107] High risk is defined as: actual value > 1.5 times the threshold or matrix in the "red zone".
[0108] In practical applications, the above process outputs an executable risk tolerance standard document containing thresholds and grading rules, a standard correlation comparison table, and a decision benchmark database that stores the mapping relationship between risk grading and control measures.
[0109] In some embodiments, in step 2,
[0110] Based on the area under the jurisdiction of the gas company and the pressure level of the pipeline to be evaluated, the pipeline to be evaluated is divided into several blocks. Each block is then identified, and the key control points within each block are identified.
[0111] After identification, all important control points are classified and sorted, and targeted management strategies are determined according to different classifications, and key areas are identified.
[0112] The identified key areas should be classified into different levels according to the severity of the consequences.
[0113] In some embodiments, in step 3, different scenarios for each risk point are identified one by one according to the key areas.
[0114] The identification is carried out according to the level of key areas. The identification and management of each key area adopts a dynamic management approach. When the corresponding pipeline to be evaluated and its surrounding environment change, the situation that can bring new risks to safety management is re-identified. Multiple causes and corresponding consequences of the same risk point are combined into cause-effect pairs as the scenarios for analyzing the corresponding risk points.
[0115] In some embodiments, in step 4, the hazardous factors in each work unit are identified. Data such as the maximum working pressure of the gas pipeline, the surrounding environment, population density, inspection frequency, monitoring methods, and the level of nearby medical facilities are collected to comprehensively and accurately identify potential risk consequences and provide a basis for subsequent risk assessment and prevention.
[0116] In some embodiments, in step 5, the unit risk value R = S × C;
[0117] Where S represents the probability of failure; C represents the consequences of failure;
[0118]
[0119] In the formula: Pᵢ: the probability of the first-level independent event occurring for the i-th triggering consequence, i=1,2,...,n, where n is the total number of first-level independent triggering events;
[0120] ∏ is the chain multiplication operator, representing the product of the probabilities of all first-order independent events "not occurring";
[0121] The probability of each first-level independent event is determined by the joint probability of all its second-level sub-events, calculated as follows:
[0122]
[0123] In the formula:
[0124] Pᵢⱼ: The probability of the j-th sub-event under the i-th primary event Pᵢ, j=1,2,...,mᵢ, where mᵢ is the total number of sub-events under the i-th primary event;
[0125] ∏ is the chain multiplication operator, representing the product of the probabilities of all second-level sub-events "not occurring" under the same first-level event;
[0126] The probability of each secondary sub-event is determined by its initial event probability and the risk reduction parameters of the accompanying independent protection measures, calculated as follows:
[0127]
[0128] In the formula:
[0129] : The parameter of the kth independent influencing factor under the i-th primary event and the j-th secondary sub-event Pᵢⱼ, k=1,2,...,tᵢⱼ, where tᵢⱼ is the total number of independent influencing factors under the i-th primary event and the j-th secondary sub-event;
[0130] ∏ is the chain multiplication operator, representing the product of parameters of all independent influencing factors under the same second-level sub-event;
[0131] each Specific definition:
[0132] Xᵢⱼ1: The initial event probability of triggering the secondary sub-event Pᵢⱼ, i.e., the baseline probability of this sub-event occurring without any protective measures;
[0133] Xᵢⱼ2 to Xᵢⱼ t The independent protection measures for mitigation of this secondary sub-event are each set of parameters based on the actual mitigation capability of the corresponding protection measure, and all protection measure parameters are independent of each other and do not interfere with each other.
[0134] The formula for calculating C is as follows: ;
[0135] in:
[0136] As an indicator The severity weight of the failure consequences;
[0137] The score for the severity of the failure consequences; The range is from 1 to 6. , , , , and Specifically, such as Figure 2 As shown.
[0138] In some embodiments, in step 6, the corresponding tolerable level is determined by assessing the consequences and severity levels of the selected risk point. The risk value for the occurrence of the consequences of the selected risk point is then calculated through the risk calculation in step 5 and compared with the tolerable level.
[0139] If the calculated risk value is less than the tolerable risk value, then the selected risk point is considered acceptable, and the assessment of the danger and risk of the next risk point continues.
[0140] If the calculated risk value is greater than the tolerable risk value, measures to meet the acceptable risk value will be formulated based on the conclusions and recommendations of key area identification, risk assessment, detection, monitoring and evaluation, etc., to set up multiple monitoring points covering the core area of the risk source, along the possible diffusion path and surrounding sensitive areas, forming a three-dimensional monitoring network and targeted risk reduction measures to ensure pipeline safety and risk control, so as to reduce the risk to a tolerable level.
[0141] In some embodiments, in step 7, real-time monitoring data is compared and analyzed with historical data and preset safety thresholds to automatically identify potential risks and hazards, and warning signals are issued according to the severity of the risks. Taking into account factors such as the warning signal level, risk development trend, and the effectiveness of control measures already taken, the risk level is re-determined, and steps 5 to 7 are executed again.
[0142] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.
Claims
1. A method for assessing the hazards and risks of urban gas pipelines; characterized in that, Includes the following steps: Step 1, determine the risk tolerance standard, specifically: Based on existing gas risk datasets, including but not limited to asset ownership, pipeline integrity management requirements parameters, pipeline operating pressure, annual inspection records, and the type and number of surrounding buildings, establish risk tolerance standards. Step 2, risk level zoning and identification of key control points, specifically: Based on the area under the jurisdiction of the gas company of the pipeline to be evaluated and the pressure level of the pipeline to be evaluated, risk level zoning and key control points are identified. Step 3, key area identification and filtering, specifically: Determine the scope, triggering causes, and consequences of key areas to prevent duplication and omissions, and ensure that risk assessment is rigorous and realistic; Step 4, Consequence and Severity Assessment, specifically: Before conducting a hazard and risk assessment, evaluate the severity of the consequences of triggering a risk point. The assessment results characterizing the severity of consequences must conform to the description of the risk tolerance standard. Step 5, risk calculation, specifically: Based on the divided work units and identified hazards, analyze the failure frequency and potential impact of each hazard, and calculate the risk value R for each unit; Step 6, Risk Management Recommendations, specifically: Based on the determined risk level and grade, different monitoring equipment and quantities are used to monitor key assessment indicators and leakage situations, thereby carrying out risk classification and control. Step 7, risk reassessment, specifically: Intelligent early warning analysis is conducted based on the monitoring data from the monitoring equipment.
2. The method for assessing the hazards and risks of urban gas pipelines according to claim 1, characterized in that, In step 1, Establish risk tolerance standards, including: Input the aforementioned structured database, data quality report, and external parameters; External parameters include HSE system documents, corporate risk appetite level, control responsibility entity coding, industry regulations and standards, and risk tolerance matrix; Enterprise risk appetite levels are categorized as Level 1, Level 2, or Level 3. When establishing standards, external parameters are first imported through programming to establish a correlation mapping between key indicators of the HSE system, industry standard thresholds and risk tolerance matrix, and the matrix weights are adjusted according to the enterprise's risk appetite level. Next, extract the qualified data, screen the core influencing factors including failure frequency and surrounding population density, and calculate the tolerable threshold for each factor. The formula for calculating the tolerable threshold is as follows: Tolerable threshold = Basic threshold × (1 + Management model adjustment coefficient - Regulatory update correction coefficient); The risk classification rules were finally determined as follows: Acceptable risk is defined as follows: the actual value of the impact factor is less than or equal to the threshold, and the matrix is in the "green zone". The risks that need to be managed are: actual value > threshold and ≤ 1.5 times the threshold or the matrix is in the "yellow zone"; High risk is defined as: actual value > 1.5 times the threshold or matrix in the "red zone".
3. The method for assessing the hazards and risks of urban gas pipelines according to claim 2, characterized in that, In step 2, Based on the area under the jurisdiction of the gas company and the pressure level of the pipeline to be evaluated, the pipeline to be evaluated is divided into several blocks. Each block is identified, and the important control points within each block are identified. After identification, all important control points are classified and sorted, and targeted management strategies are determined according to different classifications, and key areas are identified. The identified key areas should be classified into different levels according to the severity of the consequences.
4. The method for assessing the hazards and risks of urban gas pipelines according to claim 3, characterized in that, In step 3, different scenarios for each risk point are identified one by one according to the key areas. The identification is carried out according to the level of key areas. The identification and management of each key area adopts a dynamic management approach. When the corresponding pipeline to be evaluated and its surrounding environment change, the situation that can bring new risks to safety management is re-identified. Multiple causes and corresponding consequences of the same risk point are combined into cause-effect pairs as the scenarios for analyzing the corresponding risk points.
5. The method for assessing the hazards and risks of urban gas pipelines according to claim 4, characterized in that, In step 4, the hazardous factors in each work unit are identified. Data such as the maximum working pressure of the gas pipeline, the surrounding environment, population density, inspection frequency, monitoring methods, and the level of nearby medical facilities are collected to comprehensively and accurately identify potential risk consequences and provide a basis for subsequent risk assessment and prevention.
6. The method for assessing the hazards and risks of urban gas pipelines according to claim 5, characterized in that, In step 5, the unit risk value R = S × C; Where S represents the probability of failure; C represents the consequences of failure; ； In the formula: Pᵢ: the probability of the first-level independent event occurring for the i-th triggering consequence, i=1,2,...,n, where n is the total number of first-level independent triggering events; ∏ is the chain multiplication operator, representing the product of the probabilities of all first-order independent events "not occurring"; The probability of each first-level independent event is determined by the joint probability of all its second-level sub-events, calculated as follows: ； In the formula: Pᵢⱼ: The probability of the j-th sub-event under the i-th primary event Pᵢ, j=1,2,...,mᵢ, where mᵢ is the total number of sub-events under the i-th primary event; ∏ is the chain multiplication operator, representing the product of the probabilities of all second-level sub-events "not occurring" under the same first-level event; The probability of each secondary sub-event is determined by its initial event probability and the risk reduction parameters of the accompanying independent protection measures, calculated as follows: ； In the formula: : The parameter of the kth independent influencing factor under the i-th primary event and the j-th secondary sub-event Pᵢⱼ, k=1,2,...,tᵢⱼ, where tᵢⱼ is the total number of independent influencing factors under the i-th primary event and the j-th secondary sub-event; ∏ is the chain multiplication operator, representing the product of parameters of all independent influencing factors under the same second-level sub-event; each Specific definition: Xᵢⱼ1: The initial event probability of triggering the secondary sub-event Pᵢⱼ, i.e., the baseline probability of this sub-event occurring without any protective measures; Xᵢⱼ2 to Xᵢⱼ t The independent protection measures for mitigation of this secondary sub-event are each set of parameters based on the actual mitigation capability of the corresponding protection measure, and all protection measure parameters are independent of each other and do not interfere with each other. The formula for calculating C is as follows: ; in: As an indicator The severity weight of the failure consequences; The score for the severity of the failure consequences; The range is from 1 to 6.
7. The method for assessing the hazards and risks of urban gas pipelines according to claim 6, characterized in that, In step 6, the corresponding tolerable level is determined by assessing the consequences and severity level of the selected risk point. The risk value for the occurrence of the consequences of the selected risk point is obtained through the risk calculation in step 5 and compared with the tolerable level. If the calculated risk value is less than the tolerable risk value, then the selected risk point is considered acceptable, and the assessment of the danger and risk of the next risk point continues. If the calculated risk value is greater than the tolerable risk value, measures to meet the acceptable risk value will be formulated based on the conclusions and recommendations of key area identification, risk assessment, detection, monitoring and evaluation, etc., to set up multiple monitoring points covering the core area of the risk source, along the possible diffusion path and surrounding sensitive areas, forming a three-dimensional monitoring network and targeted risk reduction measures to ensure pipeline safety and risk control, so as to reduce the risk to a tolerable level.
8. The method for assessing the hazards and risks of urban gas pipelines according to claim 7, characterized in that, In step 7, the real-time monitoring data is compared and analyzed with historical data and preset safety thresholds to automatically identify potential risks and hazards. Warning signals are issued according to the severity of the risks. The risk level is re-determined by comprehensively considering factors such as the warning signal level, risk development trend, and the effectiveness of the control measures already taken. Steps 5 to 7 are then executed again.