The Credit of Fire and Explosion Index for Risk Assessment of Iso-Max Unit in an Oil Refinery

The risks of fire and explosion in oil and gas industry need to be managed. The objectives of the present study were to assess the risk of fire and explosion in Iso-max unit of Tehran Oil Refinery using Dow’s fire and explosion index and to study the influences of the controlling methods. The latest version of DOW fire and explosion index guideline was applied to calculate the fire and explosion index at process subunits of Iso-max. The important process subunits in Iso-max unit were identified based on important affecting parameters such as process pressure, temperature and material value. In next step, the important parameters affecting the fire and explosion index were identified and estimated. The fire and explosion index was calculated for each subunit. Mean time, the controlling methods for each case was identified and its influences were studied. The results revealed that, 6 subunits out of 8 studied subunits had a sever fire and explosion risk. One subunit had a heavy risk and one had an intermediate risk of fire and explosion. The separating container at high pressure was the most critical subunit of Iso-max, holding an F&E Index of 220. The reactor feeding furnace was the least dangerous subunit with an F&E Index of 122. The study showed that the application of controlling methods could reduce the F&E Index extensively.