Probabilistic Risk Assessment of Typical Process Plant Using Event Tree and Fault Tree Analysis

Qualitative risk analysis is a key part of the risk management process for projects, including energy, oil & gas and chemical final products projects. The problems addressed during the research work aim to discuss the qualitative and quantitative risk analysis of a typical process plant, with an emphasis on the strengths and weaknesses of specific methods and the differences between them. Petrochemical plants and other electricity power production plants are important facilities for the utilization of petroleum products around the world. In the present research a typical process plant is analyzed based on postulated initiating event. HAZOP study identified the roles of the different components of the system, their expected malfunctions and expected consequences based on these malfunctions. The interaction of the engineering safety feature systems and components are tabulated according to an event tree scenario. The analysis is complemented using fault tree technique to quantify the probability of a nominated system malfunction. The results showed that the percentage effectiveness of each minimum cut set with regard to the probability of total failure of the system depends upon both number of components within each set and the failure probability of each component within each set during quantitative approach. Another conclusion showed that the most critical systems in the event tree analysis is those that are leading the sequences of the event trees and which have big portion of failure probability in each sequence path.