ABSTRACT
There are many factors with different degrees of importance in explosion of fire-tube boilers and hence, reorganization, assessment and ranking of such factors by an accurate analytical method could be used as a guideline for experts related to safety programs. This study was planned to determine all effectual factors associated with explosion of oil fuel, the probability of occurrence in a specific area of industry, and also ranking of basic events. Fault tree analysis method was used in studying four fire-tube boilers located in one of the factories of Alborz Industrial City [Qazvin, Iran] to determine the effective events for occurring expected explosion accident and also to show their association. All basic events were further ranked by qualitative method. Developed fault tree showed 76 events which were connected through 42 logical gates. There were 36 basic events ranked in 11 levels according to their qualitative importance. Ranking of basic events showed that the human error factor [in management planning level] has the highest order among the factors with potential to cause boiler explosion