Rim Seal Fire Protection System
The most dangerous threats for chemical and petrochemical storage farms is a fire, specifically in case of floating roof oil tank. In recent years, the oil industry has experienced several oil tanks fires throughout the world – with some of them developing into very large disasters. The causes of such disasters start with a rim seal fire. This fire breaks out of the rim seal and continues to grow undetected, until the flames have spread over the entire seal area. By this point, the floating roof tank has become surrounded by fire. In worst-case scenarios, the intense heat that is being radiated is absorbed partially by the tank shell and the pontoon, leading the metal sheets to lose their mechanical stability. In such conditions, the roof is no longer capable of floating normally and can incline, causing the roof to sink under the fuel with a consequential full surface fire.
The most efficient way to avoid such fires is by installing an early Rim Seal Fire Protection System near the rim seal area.
In these tanks, there exists an area, which exposes the hydrocarbon vapour to air, which is known as rim seal area. This system is used in order to provide automatic fire detection and instantaneous fire suppression within this rim seal zone in incipient stage.
The complete Automatic Rim Seal Fire Detection and Extinguishing system detects even incipient fire through Linear Heat Sensor (LHS) Cables. The extinguishing vessels are permanently pressurised with nitrogen and delivers foam on to the rim seal area through discharge nozzles within very short time duration of fire detection.
The different components include:
- LHS Detection System
- Nitrogen Pressurised Foam Modules
- Electrical Panel based Automatic Actuation System
In the event of fire, the LHS detects the fire and gives an annunciation in the panel. Simultaneously, the signal is used to automatically actuate the solenoid valve fitted on the foam discharge module which is mounted on the roof of the floating roof tank.
With the operation of this foam module, foam is discharged in the rim seal area through aspirating type discharge nozzles on the pipe network and in turn extinguishes the fire.