How to calculate SIL verification?

To obtain failure data for the purchased SIS control system, transmitters, and final actuation elements, it is necessary to calculate whether the SIF meets the designed SIL level based on the redundancy structure, diagnostic coverage, common cause failures, and maintenance cycles

Hello. Regarding the use of RiskCloud for SIL calculations, China was the first country to propose that hazard and operability analyses be conducted on chemical processing units in 2009. In 2014, the Ministry of Work Safety issued Document No. 116, which explicitly stated that facilities classified as “two key types and one major type” must meet risk reduction requirements based on such analyses. From then on, functional safety assessment work was initiated in the country. There is already a lot of information available online regarding HAZOP and LOPA, so I won’t go into further detail on those here. What will be discussed mainly here is SIL calculation, which is also an issue that receives considerable attention. Verification in mathematics refers to performing the inverse operations (such as addition for subtraction problems, or multiplication for division problems) after solving a problem, in order to check whether the results of the previous calculations are correct. Our SIL verification involves, after design and installation, confirming that each SIF meets the required safety performance levels in terms of PFDavg, RRF, structural constraints, and MTTFS. RRF = 1 / PFDavg. Each safety instrument function can be divided into three subsystems: the sensor subsystem, the logic operator subsystem, and the final element subsystem. Each subsystem must meet the safety performance requirements of the safety instrumented function. http://5b0988e595225.cdn.sohucs.com/images/20190916/44a98017d4ff4451a1fd261a98cf2270.pnghttp://5b0988e595225.cdn.sohucs.com/images/20190916/44a98017d4ff4451a1fd261a98cf2270.pngMethods for SIL verification include RBD and Markov models, etc. In functional safety analysis projects, we use software based on Markov models for SIL verification, such as e*da’s exSILentia and Shanghai Gelue’s RiskCloud; in this example, RiskCloud is used for the calculations. For example: The high liquid level interlock in the methanol storage tank shuts down the inlet valve; this SIF is SIL2 (PFDavg=E-02, converted RRF=100). According to the information provided by the owner, the level gauge is a Rosemount 5300 ； The system is Hikvision HiaGuard ； The final component is the Wuzhong Instrument G-series ball valve, with the solenoid valve being ASCO 551. Based on the SIL certificates of the products, we observe that for the Rosemount 5300: SIL2@HFT=0, SIL3@HFT=1; for the HiaGuard from Allen-Bradley: SIL3. For the WuZhong Instrument G-series ball valves: SIL2@HFT=0, SIL3@HFT=1. The ASCO551 solenoid valve has a SIL rating of SIL3. By examining the capabilities indicated in the SIL certificates of each subsystem within this circuit, it can be seen that the SIF resulting from these subsystems meets the requirements of structural constraints. By establishing this circuit in the RiskCloud software, the failure data for the corresponding subsystem models available in the software’s database are retrieved (λSD, λSU, λDD, λDU). The default startup time is 4 hours, the average repair time is 4 hours, and the inspection interval is 1 year (some clients may choose a period of half a year; the choice depends on specific circumstances). As a result, the PFDavg value for this SIF is 7.67E-03, which corresponds to an RRF of 130. The resulting curve is as follows: In this calculation, values such as MTTFs, pie charts showing the contribution of various factors to PFD, pie charts showing the contribution of various factors to MTTF, SIF structure diagrams, and proportions of safety failure scores were not generated. If these are needed for the project, they can be exported from the software.

What a mess; who the hell would use that? ..............

Sharing of demonstration videos on the use of e*da Company’s internationally renowned SIL calculation software; website address: https://bbs.hcbbs.com/thread-2749773-1-1.html

Hello, are there any examples of such calculations? I’d like some guidance

For detailed examples of SIL verification, please check another post on this site: 【https://bbs.hcbbs.com/thread-2846283-1-1.html】 Thank you! Feel free to communicate!

https://bbs.hcbbs.com/thread-2846283-1-1.html　　　You can take a look at this video!