Modelling standoff distances to prevent escalation in shooting attacks to tanks storing hazardous materials

Industrial equipment storing hazardous substances can be the target of intentional malicious attacks causing escalation scenarios involving the release of flammable and/or toxic material with severe consequences on people, assets, and the environment. In the present study, a novel modelling approach was developed to assess the baseline values of standoff distances for atmospheric and pressurized storage equipment considering a set of standardized handgun and rifle projectiles not specific for military uses. The calculation of standoff distances is based on specific models for projectile perforation and flight. The range of standoff distances varies depending on the type of firearm used. Standoff distances resulted in the range of less than 10 meters in case of handgun projectiles and up to 1130 meters in case of hard-core rifle projectiles. Important differences in standoff distances were found for atmospheric and pressurized tanks. The effect of the initial offset angle of the shooter on the standoff distance was assessed by a Monte Carlo analysis based on credible offset angles for handgun and rifle projectiles. A case study demonstrates the importance of the results to improve chemical site security with respect to attack detection, emergency response, and mitigation actions aimed at preventing escalation scenarios.