Event Tree Analysis

Event Tree Analysis (ETA)

Event tree analysis is a method to illustrate the intermediate and final outcomes which may arise after the occurrence of a selected initial event.

This technique is complementary to Fault Tree, but in reversed direction.

Whereas a fault tree starts from a final event and works from the top down, an Event Tree begins with an initial event such as a power failure and explores all possible outcomes by working from the bottom up.

ETA identifies the sequences of events following an initiating event that results in accident. Event tree considers operator response or safety system response to the initiating event in determining the potential sequence.  

Some sample initial (bottom) events for ETA are:

  1. Failure of pump of_________
  2. Failure of stirring of_________
  3. Failure of water/cooling media/heating media in______
  4. Stoppage of motor at_________
  5. Mistake of__________
Event Tree Analysis (ETA)

Above illustration is for an initial event of release of flammable gas.

Advantages or Pros or Benefits of ETA:

  • Utilization is general and acknowledge all around and we can utilize it for cross-discipline framework investigation.
  • It is reasonable for some dangers in QRA that emerge from arrangements of progressive disappointments.
  • An Event tree is clear and legitimate and in this way easy to comprehend.
  • Restriction of the examination isn’t to gear related occasions
  • We can utilize it for diagnosing framework difficulties.
  • “Pre-incident” Event Trees feature both the worth and possible shortcomings of defensive frameworks (particularly distinguishing results with no mediating defensive measures).

Disadvantages or Cons of ETA:

  • It isn’t proficient where numerous occasions should happen in mix, as it brings about numerous repetitive branches.
  • Think of All occasions are to be free which can prompt missing deliberate and well known mode disappointments.
  • As the procedure utilizes twofold rationale it may not work for some mishap situations which incorporate vulnerability like human mistake or antagonistic atmospheric conditions.
  • Restriction of the investigation is to one starting occasion. In the event that estimation of time for arrival is being utilized to distinguish possible reasons for mishaps, different methods like HAZOP, FMEA a scenario in which or agendas ought to be thought of.

Read More : Five ‘E’s Of Accident Prevention