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Rajeshkumar M Modi

Process Safety
Rajeshkumar M Modi

Rajeshkumar M Modi

Lead SIF & FGS Engineer, Instrumantation Engineering Department, Oman LNG L.L.C.

RAJESHKUMAR MODI (C.Eng, CFSE(Exida) and TUV certified FSE) is an EC engineer and having > 30 years of experience in design,engineering,maintenance-&-construction of ‘Instrumentation-&-control’ systems for Chemical,Petrochemical,Oil-&-Gas,Fertilizers plants/projects -client and EPC based. Presently, working in Instrument(Engineering)-OLNG. He authored technical articles on SIS in technical publications-and-international symposium.


Process Safety

Abstract: Applied 20:20:20 rule for the entire Safety-Life-Cycle(SLC) of Safety-Instrumentation-System (SIS), the Analysis Phase takes 20 Weeks, the Design Phase takes 20 Months & Operation Phase takes 20 Years in an imprecise proportion. Therefore, the Operation Phase is the longest time span of the SLC in which all Safety-Instrumented-Functions(SIFs) remain in operation to maintain the desired Safety-Instrumented-Levels(SILs) which were assessed and designed to achieve required Risk Reduction.
In any circumstances, if SIF loop misbehaves or does not respond to demand then there are probabilities for development of Hazardous situation & may get converted into the Hazardous event.
Therefore, it is essential to test and authenticate the designed SIL of an individual SIF within predefined time period (test-interval) to maintain the desired SIL throughout the SLC. Furthermore, the other aspects like Demand-Rates & Failure-Rates are required to be monitored and compared with the considered/assumed rates during analysis phase.
Many tricks & techniques have been developed based on the enriched experience over a period of time. Additionally, international standards have also provided good supports to the end users in the descriptive manner which has created wide panorama used to achieve desired performance through various manner.
It is factual that the technological evolution have supplemented many advantages and ultimately improved reliability and availability of the SIS through accuracy,-speed-miniaturization,-power reduction,-software strength,-diagnostics improvement, etc.
This paper is describing various proven tricks & techniques which have been developed, adopted, applied and practiced in Oman LNG to verify and maintain the SIL which avoids false trip and keeps plant/unit/equipment in run state without sacrificing safety – with degraded mode for specific time interval through NAMUR NE 43 signal levels, MOS (Auto, Negative, Positive), partial stroke testing, etc.

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