Fire and Blast Hazards in Petrochemical Facilities: Design Practices for Electrical Enclosures

In industrial processing facilities, power distribution equipment is typically housed in dedicated prefabricated enclosures, which are strategically laid out in the plant to distribute power to processing units. These enclosures can contain low voltage or medium voltage switchgear, motor control centers, battery systems for backup DC power, and other control and monitoring equipment. Although these enclosures are not typically occupied by personnel during plant operations, they play a key function in controlling processes, even in critical or emergency situations. Due to their critical function in controlling processes inside the plant, this paper recommends these enclosures be risk assessed to determine if they should be designed to reduce the impact that accidental fires or explosions could have on the enclosed equipment. This paper discusses existing industry practices and technical literature that covers the blast and fire design of electrical enclosures. It further discusses a real vapor cloud explosion accident (Texas City, 2005) [10] that caused unintentional blast loading on a power distribution building.