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Fault Tree Analysis (FTA)

Fault tree analysis  (FTA) is a systematical failure assessment steps based on deductive reasoning starting from the final or top event to its lower causal events  in oder to determine the root cause of the problem. The tree is constructed by using “AND” and “OR” logic gates so that the most probable sequent of events can be determined through those logic gate multiplication. This stepwise resolution of events into immediate causal events proceeds until basic causes (primary causes) are identified. In case of failed component, the top event is the sympton observed (e.g. leak or rupture vessels or pipeline, compressor explosion, etc). In case of design phase the top event is an hypothetical most probable failure modes. In this case FTA is a deductive analysis approach for resolving an undesired events scenarios into its causes. When the failure scenarios involving very complex and multiples failure modes are formulized, a First-Order Cutsets (single events which alone trigger the top event) and the Second Order Cutsets (or higher)  can be determined. A Cutset is the name given to each of the combinations of base events which can cause the top event. The shortest cutset is the most dangerous condition that subsequently lead to final failure (top event). 

 

 

 

Benefit of FTA

a. FTA can be used to resolve the causes of system failure. 

b. FTA can be used to quantify system failure probability. 

c. FTA can be used  to evaluate potential upgrades to a system. 

d. FTA can be used to optimize resources in assuring system safety. 

e. FTA can be used to resolve causes of an incident. 

f. FTA can be used to model system failures in risk assessments.