Seismic risk in the chemical process industry: A semi-quantitative methodology for critical equipment identification

Natural events, such as earthquakes, floods, etc., can play a significant role in triggering industrial accidents of various intensities (the so-called Na-Tech risk), so that their inclusion in a comprehensive risk assessment is very important. However, a detailed and comprehensive quantitative approach is often unrealistic, because of the extremely large number of calculations to be carried out and of scenarios to be analysed. A preliminary semi-quantitative methodology is here presented for the characterization of the safety level of the different equipment items located in an industrial site, with respect to seismic hazard. Still based on objective evaluations, the presented approach allows to reduce the calculation burden, rank the equipment items in terms of relative seismic risk, and to identify the most critical items which more urgently need further attention. Along with the proposed methodology, an example of its application to a real industrial case is presented.