How to conduct SIS system certification evaluation
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In accordance with the requirements of Document No. 116 issued by the former State Administration of Work Safety, titled \"Guiding Opinions on Strengthening the Management of Safety Instrumented Systems in the Chemical Industry,\" for new installations, as of January 1, 2018, work safety supervision agencies in various regions have gradually required that new projects falling under the category of \"two key areas and one major project\" undergo SIL classification and verification. For existing installations, the assessment of their safety instrumented systems must be completed by the end of 2019, followed by necessary corrective actions. How is the evaluation carried out and what are its main contents? What are the requirements for the instrument itself? How is it done, what is the process, and what kind of documents issued by what kind of people or organizations are valid?
Just ask a design institute and you’ll know. A HAZOP analysis was conducted on the existing system, resulting in a HAZOP analysis report, a SIL level report, and a SIL verification report.
1. Whether chemical plants classified as “two key points and one major item” are equipped with safety instrument systems. Resolve the issue of whether there is an SIS system or not. 1. Hazardous chemical processes under key supervision: I. Phosgene and phosgenation processes ； II. Electrolysis Process (Chlor-alkali) ； III. Chlorination process ； IV. Nitration Process ； V. Ammonia synthesis process ； VI. Pyrolysis (cracking) process ； VII. Fluorination Process ； VIII. Hydrogenation Process ； IX. Diazotization Process ； X. Oxidation Process ； XI. Peroxidation Process ； XII. Amination Process ； XIII. Sulfonation Process ； XIV. Polymerization Process ； 15. Alkylation process. 2. Hazardous chemicals under key supervision (the first batch of 60 types). 3. Major hazard sources (mainly referring to level 1 and level 2 major hazard sources) require assessment by professional evaluation agencies. Evaluation criteria: GB 18218-2018 Identification of Major Hazard Sources for Hazardous Chemicals. II. HAZOP/LOPA/SIL analysis of the installation – The existing installation is evaluated to determine whether the current protective measures are adequate and whether the safety integrity level (SIL) of the safety instrument system meets the design requirements. In short, it is necessary to determine which safety instrumented loops need to be installed, what the SIL level is, and whether the validation of the existing safety loops meets the SIL requirements. HAZOP is one of the methods for hazard identification in quantitative risk assessment; it is applicable to process units during the design phase as well as to existing process units. It can effectively prevent/reduce the occurrence of accidents (especially serious ones). That is, how to reduce the existing risks ； LOPA analysis is a continuation of HAZOP analysis; it addresses the limitation of HAZOP analysis, which is the inability to quantify residual risks, and serves as a complement and enhancement to the results obtained through HAZOP analysis ； No matter what method is used for reduction, LOPA standards consist of seven layers; which layer should be used to achieve an acceptable level of reduction? ； SIL analysis builds upon LOPA analysis by further designing the safety instrumented systems (SIS) that need to be added, and it also verifies the results of the LOPA analysis. That is, the fourth layer involves an assessment of the device’s protection capability, determining whether the probability of failure meets safety requirements; it is a quantitative calculation for individual circuits. As mentioned above, a third-party agency is required to assist the owner with the assessment. III. Improvement and Implementation 1. The two key and one major chemical processing units that do not have safety instrument systems need to be redesigned to include such systems ； 2. If the HAZOP/LOPA/SIL analyses do not meet the requirements, safety control loops need to be added and the SIL level improved, etc. 3. Item 116 specifies the time requirements for safety assessments of existing and newly installed devices.
Based on the HAZOP analysis, a LOPA analysis is conducted to determine the SIL level.
What kind of people or organizations issuing a HAZOP analysis report make it valid?
I also want to know whether it should come from a design institute, and whether such an institute must have the appropriate qualifications to issue it; moreover, how can it be ensured that the documents produced are reasonable and compliant?
Okay, thank you. I’ll ask the manufacturers of SIS systems
At present, there are no specific qualification requirements for the entities responsible for preparing Hazop analysis reports. It is acceptable for the project owner, design institutes, engineering companies, or third-party consulting firms to carry out the analysis and preparation on their own or as part of a joint team; the key is that the joint team undertaking this task must possess the necessary capabilities and experience in this area.
A third-party security consulting firm is needed to conduct a LOPA analysis in order to determine the SIL level of the interlock circuits as well as the individual protective measures involved in various scenarios, thereby laying the foundation for subsequent life-cycle management. For example, in a situation where a company finds that its flare system’s processing capacity does not meet the design requirements after undergoing expansion upgrades, there are two main solutions: 1. Redesign the flare system； 2. Design an interlock to reduce emissions in order to achieve risk control. Therefore, an evaluation is conducted between the two options. In the first option, an investment of 10 million is assumed; in this case, the flare system will meet the emission requirements regardless of the type of hazardous scenario that occurs, and the safety valve can serve as an independent protection measure, resulting in a risk reduction of 100 times. In such scenarios, a safety instrumented system may not be necessary. In the second option, however, the safety valve cannot be used as an independent protection measure during risk analysis; hence, the additional interlocks required must have a SIL level of at least SIL2. The resulting investment amounts to only 1 million. Company A operates existing facilities on a small scale, and therefore chooses the second option for risk management. Company B is a newly established company with a larger scale; it only needs to conduct new bidding processes for procurement, and the actual cost of the modifications is 5 million. Since there are 3 similar scenarios, using the second option would result in actual costs of 6 million. As a result, Company B opts for the first option. For the same scenario, these two companies adopted different security management strategies, had varying requirements for personnel involved in security, and faced different levels of difficulty in subsequent expansion and modification. This is the significance of the safety system assessment (LOPA analysis) required by Document No. 116