Key Performance Indicators (KPIs): Consequence-Based Metric for the Assessment of Inherent Safety

The practice of inherent safety in process development and design asks for reliable and systematic assessment tools. Despite some valuable procedures have been proposed in the literature, they are commonly based on general scoring techniques and involve subjective judgment in large extent. Hence relevant biases may be introduced in the analysis, resulting in unreliable outcomes. In the present study, a novel quantitative approach developed for the inherent safety assessment of process flow diagrams in early design stages is presented. The output of the approach is a metric that quantifies the inherent safety fingerprint of the process scheme by a set of Key Performance Indicators. Physical parameters are used for the quantification of the hazard deriving from materials, process conditions and equipment characteristics. The assessment resorts to the identification and modeling of credible accident consequences on humans and equipment. The adoption of tangible parameters based on consequence modeling yields a clear and sound picture of the inherent safety performance of a design option. This was demonstrated by the application to several case studies and by the comparison with other literature approaches. In the following an example concerning hydrogen production and storage is presented.