Consequence screening

Consequence screening (Section 3.3) —By comparison to design and spacing criteria Information used in initial screening Applicable industry or company I standards j Building construction type Distances between process units and buildings... 

Consequence Screening by Comparison to Design and Spacing Criteria... 

Table 3.4 shows a composite example of one type of standard that can be used to perform an explosion consequence screening by comparison to pre-established design and spacing criteria. 

It should be emphasized that qualitative consequence screening should only remove from further consideration those buildings where there is significant industry experience to support the assessment. In Example 5 cited above, a long and successful operating history exists to support the... 

Consequence Screening Based Upon Site-specific Conditions (Section 3.3.2) identification of Evaluation-case Events... 

To perform consequence screening by modeling, the potential blast parameters from evaluation-case events must be calculated. The following possible events were considered in determining evaluation-case events. 

Buildings 2 and 3 require further evaluation after the consequence screening is completed. Risk screening can be performed first by calculating the maximum individual risk and then by determining the aggregate risk for occupants of the buildings. 

Consequence Screening by Modeling Site-Specific Conditions 35... 

Perform consequence screening by comparison to design and spacing criteria. 

Perform consequence screening by modeling site-specific conditions. 

Site-specific consequence screening for explosion can be performed either qualitatively or quantitatively, depending upon the explosion potential of the materials being handled, as well as processing conditions and other site-specific factors. In performing a consequence screening, it is necessary to select "Evaluation-case" events for consideration. This is defined as follows ... 

Selection of an evaluation-case event helps ensure that buildings are not inappropriately removed from the analysis pool because insignificant incidents were chosen for the evaluation. It also helps ensure that unrealistic or highly improbable events are not chosen for the consequence screening, requiring extensive and unnecessary analysis for incidents that, in fact, are very unlikely to occur. 

Qualitative Consequence Screening Based on Site-Specific Conditions... 

For VCEs, consequence screening is performed in a number of different ways, depending upon the level of detail desired and the tools available to the analyst. VCE consequence screening is based on an estimate of the blast parameters that could reasonably occur, given conservative assumptions about the quantity and nature of possible releases. 

It should be noted that consequence screening is performed without regard to the likelihood of an event s occurring. As a result, consequence screening does not determine risk. Furthermore, the consequence evaluation performed may not represent a detailed evaluation of consequences to the process plant. Instead, it is an approximation of expected consequences, given an estimate of potential blast overpressure and anticipated response of representative building types. The user should not mistake this evaluation for a detailed consequence assessment. 

Again, since the purpose of both initial and consequence screenings is to establish which buildings in process plants require further evaluation and which buildings do not require further consideration, the assumptions made in the studies should be conservatively chosen. This conservatism will help ensure that all buildings potentially exposed to significant blast are appropriately evaluated. 

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