Quantitative ISD scoring for design option comparison
Inherent Safety Index methods (Heikkilä, INSET, PIIS) provide quantitative scoring of design alternatives. We apply the most appropriate index for the design stage and decision context, generating comparable, defensible outputs.
Select ISD index method per project stage — Dow Fire & Explosion Index (FEI) for unit-level, Dow Chemical Exposure Index (CEI) for toxic, Mond Index for refined screening, INSET (Inherent SHE Evaluation Tool), i-IS-Index (Heikkila-Hurme); align with CCPS / IChemE ISD guidance.
Compile process data per index — material flammability / reactivity / toxicity, inventory per node, process temperature / pressure, equipment type and arrangement; align with HMB and P&ID source documents.
Calculate index per node — F&EI (material factor × general process hazard × special process hazard), CEI (toxic dispersion concentration × distance); apply banding (low / moderate / intermediate / heavy / severe) per Dow / Mond reference scales.
Apply ISD principles — Minimise (inventory reduction), Substitute (less hazardous material), Moderate (temperature / pressure / dilution), Simplify (process simplification); identify design options per node and quantify index reduction.
Quantify capex / opex impact per option; compare against index reduction and downstream LOPA / SIL / FERA credit; conduct trade-off analysis with non-ISD risk-reduction options (engineering safeguards); align with ALARP gross-disproportion.
Issue ISD recommendation register with risk-rank, capex / opex estimate, and implementation timeline; integrate with FEED decision-making and HAZOP/SIL workflow; align with CCPS RBPS Inherently Safer Design element.
Complete Inherent Safety Index Assessment scope — every calculation, drawing, specification, and construction support activity.
Speak with our team to scope an engagement tailored to your facility, regulatory context, and lifecycle stage.