The storage of flammable liquids with a high vapour pressure, in particular crude oil, poses challenges in view of fire prevention and safety. 

Atmospheric storage tank fires are relatively rare, but because they store large amounts of flammable liquid in them, they can have catastrophic consequences. In a recent study, the causes and costs of 104 accidents were classified. The initiating events in 38% of the accidents were environmental factors, 20% equipment factors, 15% operational factors (human error), 13% domino effect, 10% maintenance factor and 4% terrorist attack. The average cost for accidents that have produced domino effects was approximately 24,181,673 $, and for accidents without domino effects, it was 205,191,298 $. [1]

An unprotected fire incident can quickly result in large-scale fires, explosions and thick vapour clouds; all of which cause danger to infrastructure, people and the environment. Business interruption with impact on various stakeholders is also a risk in this context.

Owners and operators of crude oil storage facilities have several options to mitigate fire events. NFPA 30 (Flammable & Combustible Liquids Code) provides certain guidance; but in addition to codes and standards, owners and operators may want to consider a risk-based approach.

For example, should they let the fire burn out the stored fuel without any fire-fighting activities at the burning tank or maybe couple this rather passive approach with limited protection measures in which they cool the surrounding infrastructure (tanks, process equipment, etc.) to prevent escalation of the fire event (i.e. to prevent so-called "domino effects"). Or, they decide to actively attack the fire, by using fixed and/or mobile fire protection systems to suppress the fire. Fixed foam suppression systems typically consist of foam storage tanks, proportioning/mixing devices and foam discharge devices, the latter located at the top of the tank (e.g. foam chambers).

[1] Ahmadi, O., Mortazavi, S.B. & Mahabadi, H.A. Review of Atmospheric Storage Tank Fire Scenarios: Costs and Causes. J Fail. Anal. and Preven. 20, 384–405 (2020). https://doi.org/10.1007/s11668-020-00846-5