【Weekend Share-15】When is the SIL assessment and classification for chemical enterprises carried out?

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1. When is the SIL assessment and classification for chemical enterprises carried out? 【Answer】Under normal circumstances, the SIL verification is carried out in the early stage of project construction, before purchasing equipment such as safety instrument sensors, SIS systems, and isolation valves; the data obtained from this verification are checked to ensure they meet the requirements before procurement and installation take place. But at present, it is generally done by calculating based on the equipment installed on site after the installation is complete. Since almost all instrumentation devices are equipped with high-end specifications, failures in the verification tests are rare. Moreover, the probability of instrument failure is closely related to its installation on-site; the proper selection and installation of instrumentation devices are directly related to their safety and reliability. Therefore, most verification tests are carried out after the equipment has been installed but before the project is accepted. [Reference] According to Section 7.3.7(4) of the \"Guidelines for Safety Risk Prevention and Control in Hazardous Chemicals Production and Construction Projects (Trial)\", jointly issued by the Ministry of Emergency Management, the **National Development and Reform Commission, the Ministry of Industry and Information Technology, and the State Administration for Market Regulation, it is necessary to determine, at the preliminary design stage, the functional requirements for safety instrument functions (SIF) as well as the required safety integrity level (SIL), in line with the risk reduction measures suggested by process hazard analysis. Additionally, it is required to prepare an assessment report on the safety integrity level (SIL) and technical documents outlining the safety requirements for the safety instrument system (SIS). (5) Before the commissioning of a construction project, it is necessary to conduct a Safety Integrity Level (SIL) verification of the integrity of each Safety Instrumented Function (SIF) circuit, in order to prove that the designed SIF circuits meet the requirements specified in the SIL classification report. They must also comply with the structural constraints (redundancy and fault tolerance) and system constraints (product certification) required by relevant standards. Additionally, the inspection and testing schedules as well as the testing methods should be determined appropriately in accordance with the design requirements.