Hazard Analysis and Risk Assessment

Abstract

The purpose of hazard analysis and risk assessment in the chemical process industry is to (1) characterize the hazards associated with a chemical facility; (2) determine how these hazards can result in an accident; and (3) determine the risk, ie, the probability and the consequence of these hazards. Methods for performing hazard analysis and risk assessment include safety review, checklists, Dow Fire and Explosion Index, what-if analysis, hazard and operability analysis (HAZOP), failure modes and effects analysis (FMEA), fault tree analysis, and event tree analysis. In order to complete an assessment of risk, a probability must be determined. A more recent concept which could have significant impact on future designs is that of inherent safety. Hazard avoidance is performed by three techniques. First, there is substitution. This means substituting a less hazardous material for the material in use. The second method for inherent safety is attenuation, ie, operating the process at lower temperatures and pressures. The last inherent safety technique is intensification. This means using much smaller inventories of hazardous raw and intermediate materials, and reducing process hold-up and inventories.