How can SIL be achieved without SIS?
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It is a small production unit without any hazardous processes; it is classified as a Level 3 major hazard source. According to relevant regulations, it is not necessary to install an SIS, so no such system was installed. However, after an inspection by experts, it was required that a SIL be installed. From the information I have found, all SILs are related to SIS systems. At present, we need to find a way to meet the experts’ requirements; otherwise, they will refuse to sign. What should we do? Are there still relevant regulatory standards that can be used to counter this? Thank you so much!
GB 20438, GB 21109, GB 50770 – You can take a look at these. The SIL classification requires you to conduct HAZOP and LOPA analyses; whether a SIS is necessary depends on the results of the SIL classification. This is just my personal opinion; I hope it can help you
Originally, any system with two critical points and one major point was required to undergo an SIS assessment in order to determine its SIL level.
SIL is the certification for instruments, right? Does it mean that if an instrument has SIL certification, that’s sufficient? In that case, it’s sufficient to specify requirements when purchasing the instruments. SIL certification is quite common for instrument manufacturers
What needs to be done is not only for compliance and personal safety; if there aren’t many circuits, purchasing SIL-certified sensors and valves, and using safety relays for hardwired connections, can help achieve a SIL rating
First conduct HAZOP and LOPA analyses; if there are no issues, there is no need to implement SIS
SIL is not designed for SIS; generally, HAZOP is conducted first, followed by the determination of SIL levels for the interlock circuits. Based on the results of the qualitative device-based analysis (HAZOP analysis), a Layer of Protection Analysis (LOPA) is conducted on the hazardous incident scenarios associated with the Safety Instrumented Functions (SIFs), in order to determine the minimum reliability requirements for each SIF circuit and thereby reduce the risks in the production process
According to Document No. 116 issued by the State Administration of Work Safety in 2014, there is a basis stating that you need to install a SIS that meets the required standards; where can you find regulations that allow you to omit the installation of a SIS? ?
I agree with you. SIL and SIS are two different concepts: one is the Safety Integrity Level, and the other is the Instrument Safety System. Before the construction of new installations, HAZOP analysis and LOPA analysis are generally carried out. LOPA analysis focuses on hazard sources by performing independent protection layer analyses and grading the safety instrument functions (SIF). Generally, circuits with a SIL level of 1 or higher are required to be integrated into the SIS system, while circuits with SIL level 0 do not have such a requirement.
SIL is not designed for SIS. Instead, the SIL level of the circuits is determined through HAZOP and LOPA to identify which circuits require a SIS.
First, conduct a HAZOP on this set of equipment to identify relevant risks； Then, LOPA is conducted for each risk trigger. The purpose of LOPA is to determine whether safety instrumented functions (SIFs) are necessary; if other protection layers can reduce the risk to a level acceptable according to regulations, then SIFs are not required, otherwise SIFs must be used to achieve the desired goal ； If it is confirmed that an SIF is required, the circuit can be classified to determine the SIL. Finally, based on the above, the Safety Instrumented System (SIS) is designed, including the determination of the redundancy mode and equipment selection.