Availability & Reliability

Availability & Reliability

Fault Tree Analysis

EPConsult Energies has extensive expertise in performing Fault Tree Analysis (FTA) for offshore and onshore oil and gas projects.

FTA and Event Tree Analysis (ETA) are methods of calculating the probability of hazardous scenarios from the failure rate of causal events - root cause analysis (RCA). Often, what we are attempting to establish is the top event; Probability of Failure on Demand (PFD); e.g. the probability that a High Integrity Pressure Protection System (HIPPS) valve would not close on demand.
FTA can be applied in a wide variety of ways, some of which include:

  • To perform Safety Integrity Level (SIL) validation
  • To calculate the reliability of a system that has to operate on demand, e.g. quick release mechanisms, emergency shutdown systems, firewater systems and high integrity pressure protection systems (HIPPS)
  • To calculate the initiating event for an Event Tree Analysis (ETA), e.g. as part of the Quantitative Risk Assessment
  • To calculate reliability of components such as valves and connectors from reliability data relating to their component parts
  • To calculate the likelihood of a particular hazardous scenario in terms of the likelihoods of equipment failures and human errors leading up to it

FTA is a defined, structured and rigorous visual tool that displays the logic interfaces of components within a system, including redundancies and common cause failures. It utilises Boolean algebra probability and reliability theory. It is built up by logic AND and OR gates and provides great flexibility in studying:

  • Best configuration for a system
  • Required component reliability to achieve pre-defined PFD
  • Optimum voting (XooY) for sub-systems instrumentation
  • Optimum redundancy for components
  • Optimum testing intervals

FTA is thus applicable for many types of analyses in our industry; for safety, reliability, availability, maintenance optimisation and accident investigation. There is a strong link to Root Cause Analysis (RCA). In most cases we recommend performing FMECA prior to performing FTA, unless the system is simple.

To know more or discuss FTA and related subjects, please contact us at enquiries@ep-consult.co.uk