What is the relationship between HAZOP analysis, SIL classification, SIL verification, and P&ID diagrams?

Conduct HAZOP analysis reviews using criteria such as PID, then determine whether the risks can be reduced through process improvements, and finally assign a SIL rating.

My understanding (including some scattered information I received from companies earlier on) is as follows: factory process flow – HAZOP by the design institute – PID and SIL classification by the design institute (performed by a qualified third party) – further development of the PID design by the design institute (based on the measures determined as a result of the SIL classification) – SIL verification (by another qualified third party?) ) – Whether it meets the SIL requirements specified by regulations. Please, master, advise me whether such a process is correct! Existing SIL-rated companies treat it as a one-time deal and are unwilling to engage in repeated discussions with the design institutes; that is, once the design institute has refined the PID, they are reluctant to re-evaluate the SIL level. To re-classify it, it would cost the amount specified in two contracts.

When is the HAZOP analysis method carried out? 1. Projects with two key points and one major aspect are required to be carried out during the design phase; so, which stage of design is that? We generally believe that HAZOP is carried out after detailed design, when complete P&ID diagrams are available. If methods such as WHAT IF can be used during the preliminary design phase. 2. HAZOP analyses also need to be conducted simultaneously for projects such as modifications and capacity expansions; detailed, complete, and accurate P&ID drawings are required in the preliminary stage as well. 3. **Document No. 76 requires that HAZOP reviews be conducted for ongoing projects within 3 years. After the HAZOP analysis is completed, semi-quantitative analysis is conducted on some severe 【hypothetical accident scenarios】 to determine the SIF loops that require a SIL rating. SIL verification: Before designing the SIF circuit and starting its operation, the safety level of the SIF circuit is verified. Please contact me for further communication. Thank you

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HAZOP analysis is based on round-table meetings, brainstorming, and qualitative safety analyses involving the owner, design institute, supplier, or process package manufacturer using the latest version of the PID diagram (including the operational phase, conceptual design, and detailed design phases)； The SIL classification is based on a semi-quantitative analysis of safety instrumented function circuits using causal chain diagrams; in simple terms, it determines how many such circuits are required to achieve an acceptable level of risk ； SIL verification is based on the SIL classification; for example, if the SIL classification is SIL2, it involves verifying whether the instrument loop – including sensors, logic controllers, and actuators – can meet the SIL2 standards.

HAZOP analysis is conducted using PID and interlock conditions, and risks are then reduced through process-related measures; if it is not possible to reduce the risks, a SIL classification is determined in the end.

1. Through HAZOP analysis, various potential dangers and hazards in process units or facilities can be identified systematically, and reasonable and feasible measures can be implemented to reduce the likelihood of accidents and their consequences； 2. By introducing the Layers of Protection Analysis (LOPA) technique based on HAZOP analysis, it is possible to address the shortcomings of HAZOP analysis, such as the inability to quantify the risk reduction achieved by safety protection measures and the residual risks. Therefore, LOPA analysis is a continuation of HAZOP analysis, serving to enrich and complement the results of HAZOP analysis ； 3. SIL analysis builds on LOPA analysis by further designing the safety instrumented systems (SIS) that need to be added, as well as verifying the results of the LOPA analysis; in other words, HAZOP and LOPA analyses serve as the preliminary steps for SIL analysis ； 4. SIL verification. The SIL level is determined by evaluating the circuit, which includes input elements (pressure, temperature, flow, level transmitters, etc.), logical operations (the logic operators of the safety instrument system), and output elements (such as control valves). Based on the PFDs of each component purchased (the required failure probability, provided by the instrument manufacturer), it is determined whether the actual SIL level of the circuit meets the design requirements. 5. The P&ID is the information required for the analysis mentioned above; third-party HAZOP analysis firms generally quote their fees based on the number of pages in the P&ID and its complexity. The relevant standards are listed in the attachment.

The GB18218 certificate upstairs has expired; it needs to be updated