RiskCloud – Precise SIL verification module based on the Markov algorithm, FTA software, JSA software, FMEA software (useful article on LOPA)

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I. Key points summary: LOPA analysis is a continuation of HAZOP analysis, serving to enrich and complement the results of HAZOP analysis. SIL calculation is a verification of the LOPA analysis results, while HAZOP and LOPA analyses are the preliminary steps for SIL analysis. II. Definition of LOPA: Layer of Protection Analysis, commonly abbreviated as LOPA, is a systematic method that, based on the identification of hazards in a device, further evaluates whether the safety protection measures in place are effective and helps make risk-related decisions. It represents an extension and refinement of the Hazard and Operability Study (HAZOP) technique, and it is a safety risk assessment and management technique that has been widely used internationally in recent years with proven effectiveness. Unlike many qualitative risk assessment techniques (such as HAZOP), LOPA is a semi-quantitative risk assessment technique. LOPA typically uses the frequency of initial events (some unintended events), the severity of the consequences of accidents, and the order of magnitude of the failure probability of independent protection layers (some independent and effective protective measures) to approximate the risk of accident scenarios. The main purpose of LOPA is to determine whether the installation has sufficient protective measures to prevent accidents (or whether the risk is tolerable). III. Laws and Regulations In 2015, China issued the \"Guidelines for the Application of Layer of Protection Analysis (LOPA) Method\" (AQ/T 3054-2015), which stipulates the technical requirements for chemical enterprises to use the LOPA method. In 2017, the \"Guidelines for the Application of Layer of Protection Analysis (LOPA)\\" (GB/T32857-2016) was issued, which stipulated the relevant strategies and details for LOPA technology. In 2020, Su Ying Ji [2020] No. 1, the \"Guiding Opinions on Improving the Inherent Safety Level of Hazardous Chemical Enterprises,\" stipulated that production units and storage facilities classified as \"two key types and one major type\" should be equipped with safety instrumented systems that meet the required standards, based on Layer of Protection Analysis (LOPA). IV. LOPA analysis method LOPA analysis is a simplified risk assessment method that determines the ability of existing protective measures to eliminate or reduce risks by quantitatively evaluating their reliability. The application of LOPA is generally carried out after a qualitative hazard assessment (such as HAZOP, PHA), using the scenarios identified by a qualitative hazard review team. It first analyzes the risk level before any safety measures are implemented, and then examines the extent to which various safety measures reduce that risk level. The concept of protective layer analysis can be illustrated using an \"onion\" as a model: each layer of the onion’s skin represents a protective layer. Since all these layers provide independent protection for the core, the risk of the onion’s core being damaged by external forces is **reduced**. V. The specific steps for LOPA analysis are as follows: 1 Identify the consequences and select the scenarios required for the analysis. The scenarios required in LOPA analysis are essentially the accident scenarios. An accident scenario is the chain of events that constitute an accident, including the initiating event, a series of intermediate events, and the resulting events. Generally, incidents with serious consequences are analyzed as accident scenarios. 2 Provide a detailed description of the selected accident scenarios. In LOPA analysis, it is necessary to quantify the causes of an accident, the consequences resulting from it, the severity of those consequences, as well as the unacceptable and acceptable levels of risk. The criteria for such quantification should be based on the company’s actual conditions, using the company’s own risk matrix. 3 Identify the initial events, intermediate events, and outcome events of the scenario, and determine their respective probabilities. The initial event, that is, the cause, becomes the initiating event in LOPA analysis ； Intermediate events, namely triggering events, become conditional events in LOPA analysis ； Consequence events, namely the serious outcomes that result. The corresponding frequency needs to be determined based on the actual conditions of each company. 4 Risks of the projected scenario. The projected scenario, namely the unmitigated event, refers to the occurrence of the consequence event when the initial event takes place and all protective layers fail. The frequency of unmitigated events equals the product of the frequencies of the initiating events, intermediate events, and consequence events. 5 Determine the independent protection layer (IPL) and its required failure probability (PFD). The protection layers are divided into an event prevention layer and a consequence mitigation layer. The event prevention layer, also known as the active protection layer, prevents accidents by introducing a barrier between the cause and the event ； The consequence mitigation layer, also known as the passive protection layer, reduces the impact of accident consequences by introducing a barrier between the event and its outcomes. The PFD varies for different protective layers. 6 When an independent protection layer is considered, determine the residual risk of mitigating the event and its level. Reducing the frequency of occurrence of events is equal to the frequency of occurrence of unmitigated events multiplied by the failure probability (PFD) of each safety protection measure in the independent protection layer. After determining the frequency of incidents, the frequency level and residual risk level are determined based on the company’s risk matrix. 7 Determine the additional level by which the protective layer needs to be improved to achieve an acceptable risk level. If the independent protective layer serves as a safety measure and reduces the residual risk of incidents to an acceptable level for the company, then no further safety or preventive measures are required. Otherwise, practical additional protective layers must be proposed until the remaining risk is reduced to an acceptable level. VI. Conclusion Identifying and determining the IPLs in a scenario, as well as selecting the appropriate PFDs, are the core aspects of LOPA analysis. In practical applications, it is necessary to carefully identify various IPLs in order to prevent their misuse or being overlooked, thus ensuring a more comprehensive and systematic identification of hazards within the process. VII. Conducting LOPA analysis with software 1. The function of copying entire rows in LOPA, along with the Ctrl+C shortcut, greatly improves efficiency. 2. The user experience with RiskCloud is similar to that of Excel, and since almost all users are very proficient in using Excel, this enables them to work more efficiently. ============== Shanghai Guelue Software Technology Co., Ltd. (Guelue Software) is a company that specializes in providing high-end software for security risk management. Headquartered in Shanghai with a registered capital of 30 million yuan, it has currently established a marketing center in North America. The main clients are enterprises involved in the manufacturing and use of hazardous chemicals, such as those in the oil, chemical, energy, and pharmaceutical industries. GeLue focuses on the development of software and analysis tools for safety risk management, as well as providing high-end consulting services. Since its establishment, Guelue has always adhered to the principle of continuous independent innovation. Guelue’s philosophy is “if not number one, then be the only one”. Over the past 10 years, Guelue has successively launched a number of software products featuring world-class advanced technologies. It enjoys a high reputation in the fields of information technology for safe production and safety risk analysis software, and has numerous successful cases to its credit. Over the past decade, through the continuous efforts of top IT and security experts both at home and abroad, a variety of world-leading technologies have been developed. In particular, the custom analysis method technology has pushed the boundaries of what is possible, achieving results that foreign companies have struggled to attain for years; it is a source of pride for domestic brands. RiskCloud has won numerous **patents and technology awards. Its functional modules include not only the core HAZOP analysis, SIL grading, and SIL verification functions based on Markov model algorithms as described in this book, but also various other modules such as FMEA, CyberRisk, and QRA. It is also possible to define risk analysis methods tailored to specific customer needs, as well as create custom risk analysis templates.