Fire consequence evaluation, risk

Chapters 3, 4, and 5 describe various methods of evaluating hazard consequences and risk associated with buildings in process plants. Buildings for which there remains a concern following evaluation may be at significant risk from explosion or fire hazards. As discussed in Chapter 5, these buildings may be candidates for risk reduction. 

Formal Safety Assessments (FSAs) are built aroimd the concept of acceptable risk. For example, the decision as to whether a firewall should be installed between two sections of the platform will depend on the associated risk, that is, the nature of the hazard (spreading fire, consequence of the fire, and likelihood of its occurrence). The risk evaluation will then be repeated assuming the presence of a safeguard (in this case the firewall). 

Figure 5-1 shows how the FHA is integrated into an overall risk assessment. A process hazard analysis is required to identify likely fire scenarios that are carried forward to the FHA. An FHA provides the tools to characterize the hazards and evaluate consequences. The results are incorporated into an overall risk assessment. See Chapter 6 for more information on fire risk assessment. 

The main identified risks for these operations are the possible escape of sodium (with fire risk — although the sodium is low-temperature which reduces this risk), and the hydrogen risk generated by the transformation into caustic soda. A safety report evaluating these risks in detail and the counter-measures implemented to reduce their occurrence and consequences has been prepared in order to obtain the necessary authorizations from the DSEM. 

The use of computer modeling for rapidly and easily estimating the effects from explosions, fires, and gas releases is almost commonplace in risk evaluations for the hydrocarbon industry. Specialized risk consultants and even insurance risk offices can now offer a variety of software products or services to conduct mathematical consequence modehng of most hydrocarbon adverse events. Even major petroleum companies have bought... 

Fusible Link a mechanical release device actiwited by the heat effects of a fire. It usually consist of two pieces of metal joined by a low melting solder. Fusible links are manufactured as various incremental temperature ratings and are subjected to varying normal maximum tension. When installed and the fixed temperature is reached, the solder melts and the two metal parts separate, initiating the desired actions Hazard Analysis the systematic identification of chemical or physical characteristics and/ or processing conditions and/or operating conditions that could lead to undesired events Hazardous Area, Electrical a US classification for an area in which explosive gas/air mixtures are, or may be expected to be, present in quantities such as to require special precautions for the construction and use of electrical apparatus HAZOP an acronym for Hazard and Operability study, which is a qualitative process risk analysis tool used to identify hazards and evaluate if suitable protective arrangements are in place if the process were not to perform as intended and unexpected consequences were to result... 

Scenarios included in evaluated QRA methodology cover only the risk from fire following the gas leaks. Other possible consequences of gas pipeline disruption (e.g. blast) are not mentioned nor discussed and neither the risk from effects other than fire and its share in total level of risk is determined. This restriction of events further examined was identified as a main source of uncertainty in the QRA process. 

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