The role of hazard and operability study in risk analysis of major hazard plant

Abstract Under the CIMAH Regulations and the Seveso Directive the operators of major hazard plant and storage are required to prepare a safety case. The essential elements of a safety case are: the safety policy, description of hazards arising from the activity, account of controls to minimize the effects of these hazards, consequences should these controls fail, on/off site emergency plans etc. The proven method of hazard identification, called the Hazard and Operability Study, is used extensively to enhance the safety of plant during design and for existing plant. The study gives a better value for money in the art of hazard identification than the checklist approach and may be used for (a) future modifications; and (b) as a support document for ‘Safety Case’ preparation for identification of top events and for constructing fault/event trees for further frequency analysis. This paper highlights how the technique has been used in Snamprogetti Ltd at the design and operational stages of the plant.