Since 1987 – Safety Consultancy

Fault Trees Analysis – FTA

Fault Trees analysis is employed to assess the expected frequency of the top-events identified during Hazard Identification phase (case histories, HazOp, FMEA/FMECA, random ruptures, etc.).
Eidos uses multiple licenses of Reliability Workbench from Isograph Ltd to develop graphical and detailed fault trees with extensive stochastic analysis.
Eidos uses the major failure databases (OREDA, SINTEF, IEEE, etc.) for Initiator and Enabler events using the best suitable theoretical models (MTTR, Rate, Dormant, Weibull, Sequential, etc.). All the base events are modelled using stochastic distribution to weight the uncertainty of the data extracted by failure databases.
Eidos developed in house more than 500 Markov Chains.
Eidos uses Teseo 2.1, a complete in-house developed model to assess human error frequency or probability.
Eidos develops the following additional analysis for each fault tree:

  • Montecarlo
  • Sensitivity (to evaluate the sensitivity of top-event frequency to variation of failures rates)
  • Barlow-Proshan (to evaluate the contribution of every single cause)
  • Sequential (to evaluate the importance of every single protection)
  • Cut-sets
  • Time-dependent (to assess the aging of the equipment and to evaluate the correctness of the maintenance activities and frequencies)

This detailed analysis allows us to identify the main causes, the more relevant protections and all the other information needed during the risk mitigation phase.

Eidos developes Fault Trees and Markov Chains fully compliant with IEC 61025 and IEC 61165.

Once the expected frequency of a top-event is known, Eidos applies a proprietary method to develop Event Trees Analysis – ETA.


Why Eidos? For our position, for our methods, for our indipendence and for our "4ity" approach! Click Here!