Use of Two Complementary PHA Studies to Address FIRE, Explosion and BLEVE Risk in a Propane Storage Vessel

Operating a pressurized vessel that contains flammable fluids is always a concern, especially when it is located close to administrative buildings. One of the key elements for effective risk reduction is determining an adequate facility siting, taking into account that the explosion of a pressurized storage tank with only 1000 gallons of propane can have a blast radius of 10 to 30 meters. However, the available area for the facility siting, operational restrictions (e.g. location of gas feed lines) or design errors can result in locating pressurized equipment under the recommended separation distances. This paper presents a case study of a plant where administrative buildings are located less than 30 meters away from a pressurized vessel, which stores liquefied propane from a closed-loop refrigeration system. Current plant management recognized the risk of fire, explosion or BLEVE (Boiling Liquid Evaporating Vapor Explosion) scenarios. This led to the decision of implementing two PHA complementary techniques (failure mode and effects analysis or FMEA and Bow-Tie analysis, or HAZID), in order to identify the causes of these scenarios and assess the effectivity of current prevention, control and mitigation strategies. The implementation of these PHA resulted in the evaluation of the need for improvements or additional risk treatment options. This paper presents the approach taken to analyze the system and to identify the needed actions to improve risk management with an adequate cost-benefit that allows for a timely implementation, presenting an effective and efficient study scheme that can be used by operations with similar issues.