System safety assessment history

But, no statistical, historical performance measurement system can assess the quality of safety in place that encompasses low probability-high consequence incidents since such events seldom appear in the statistical history. Example A risk assessment concludes that a defined catastrophic event, one that has not happened and is not represented in the statistical base, has an occurrence probability of once in 200 plant operating years.)... 

A bit of history on the evolution of system safety will give an insight into its origins, the need for the hazard analysis and risk assessment techniques which were developed, and the place that system safety has attained. Authors don t agree on when or where it all started. But, all the historical references on system safety do relate to the military or to aeronautics. 

The safety and risk of a hydrocarbon facility cannot be assessed solely on the basis of fire fighting systems or past loss histories. The overall risk can only be assessed by defining loss scenarios and an understanding of the risk philosophy adopted by senior management. 

The system starts with project/process definitions and process conceptual design. The event history and application standards are applied to the conceptual design to obtain the process safety information. Now, the entire system is subject to PHA to obtain details about various consequences. After applying the available protection layer the situations are reassessed for SIF. As discussed earlier, target SIL assessments are also done. So, finally, all the following components form the SRS for SIS ... 

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