Risk Assessment of large Hydrocarbon Storage tanks G. Unnikrishnan, - PowerPoint PPT Presentation

Risk Assessment of large Hydrocarbon Storage tanks G. Unnikrishnan, Kuwait Oil Company

What QRAs can tell Incident/failure  Location Specific frequencies Individual Risk Identification  Risk transects Measures Of incident of Risk scenarios  Frequency – Fatalities (FN Consequences Impacts Curve)

Risk Contours Risk transect

ASSURANCE Project: Benchmarking exercises for QRA methods Variations in predicted frequencies of FN Curve defined levels of fatalities ranging between 2 and 4 orders of magnitude by different analysts .

Will QRAs would have predicted this ? Jaipur. India: 29 October 2009: 13 Buncefield. UK: 10 Dec 2005: San Juan. Puerto Rico: 23 Fatalities. Property Property damage, October 2009: Property damage, Environmental Environmental impact damage, Environmental impact impact

Buncefield. Why it happened  There should be a clear understanding of major accident risks and the safety critical equipment and systems designed to control them.  Time and resources for process safety should be made available.  There should be systems and a culture in place to detect signals of failure in safety critical equipment and to respond to them quickly and effectively.  There should be effective auditing systems in place which test the quality of management systems and ensure that these systems are actually being used on the ground and are effective.  At the core of managing a major hazard business should be clear and positive process safety leadership with top management involvement and competence to ensure that major hazard risks are being properly managed.

Buncefield. Recommendations (20)  Systematic assessment of Safety Integrity Level requirements  Protecting against loss of containment using high integrity systems  Engineering against escalation of loss of primary containment  Engineering against escalation of loss of secondary and tertiary containment  Operating with high reliability organizations  Delivering high performance through culture and leadership

Jaipur. Why it happened  The Loss of containment in terms of time & quantity was never considered a credible event and accordingly not taken into hazard identification.  Basic operating procedures for hammer blind opening was not followed.  Accident could have been managed if safety measures provided in control room were not made defunct.  Backup for emergency shutdown from Control room not available.  There was delay in emergency response for long period.

Jaipur. Recommendations (118)   Engineering related Use of Remote Operated Valve   Operation related Tank dike valves –position indicators in Control room  High reliability High level alarm  Procurement related  Automation of Tank Farms in terms of hardware and  Training related software  Policy related  Written emergency procedures & training  Maintaining Shift manning levels at all times  Installation of CCTVs  Installation of Hydrocarbon Gas detectors

What can be done ? Bow Tie Diagram and concept of Barriers

Existing methods : Fault Tree Event Tree

Bow Tie Diagram: Combination of Fault Tree & Event tree

Barrier Failure Initiating event probabilities Barrier Failure probabilities Consequence probabilities probabilities Hazardous event probability

Thank you Thank you Q & A Q & A