By Srikanth Vengasandra, Ph.D., Product Manager, Flame & Gas Detection Group, Rosemount Analytical
On January 1, 2015, eight tanks at a truck unloading station in Alexander, North Dakota, caught on fire, setting ablaze approximately 1,600 barrels of crude oil. Although the cause of the fire remains under investigation, the incident underscores the need for preventive and alternative methods to protect against the risks of tank fires and explosions.
Often the most common type of fire in floating roof tanks is the rim-seal fire. Rim-seal fires occur whenever crude oil vapors escape through worn seals, accumulating on tank skirts. These leaked vapors can be ignited, often by lightning, resulting in a fire around the tank perimeter. According to data obtained from the Large Atmospheric Storage Tank Fire (LASTFIRE) project, rim-seal fires occur at a rate of 0.3 to 21 x 10-3 incidents per tank year, with Nigeria, Thailand, and Venezuela reporting the highest frequencies.