Process hazard analysis methodology selection

For every new tolling situation a process hazard analysis should be conducted using one of several acceptable methodologies in common use. The goal is to select a methodology appropriate to evaluate the hazards of the toll process in question. 

If a recommendation asks for a change in the process, the action must undergo a formal process hazard analysis (PHA) study, such as a HAZOP or other methodology, before implementation. This systematic and formal approach identifies and evaluates hazards associated with the proposed revisions. The study may uncover failure scenarios, adverse consequences, and obscure relationships that are not immediately apparent. The CCPS publication Hazard Evaluation Procedures i is an excellent guide to selection and proper application of PHA methodologies. 

With the PHA methodology selected, the team assembled and the process safety information gathered, the analysis of chemical and process hazards, and the consequences and deviations associated with those hazards are identified. 

Introduction Theprevious sections dealt with techniques for the identification of hazards and methods for calculating the effects of accidental releases of hazardous materials. This section addresses the methodologies available to analyze and estimate risk, which is a function of both the consequences of an incident and its frequency. The apphcation of these methodologies in most instances is not trivial. A significant allocation of resources is necessary. Therefore, a selection process or risk prioritization process is advised before considering a risk analysis study. 

Selection of a PrHA methodology requires consideration of many factors including the availability of process information such as experience with the process, changes that have taken place, reliability, aging, maintenance, etc. If it is a new process, less reliance can be placed on experience and greater reliance must be placed on the analysis of possible accidents and accidents in similar or related processes. Size, complexity and hazard severity influences the dunce ot ihe most appropriate PrHA methodology. 

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