bowties - a visual view of risk
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Sunday, 06 October 2013
Bowties – a visual view of Risk
World Class Process Safety Management for Power Generation
Sunday, 06 October 2013
Overview of bowties
Where did they come from?
Butterfly diagrams evolved from Cause Consequence diagrams
First mention of bowties in 1979 by University of Queensland but adapted from ICI plc Hazancourse notes
Post Piper Alpha –Royal Dutch/Shell Group integrated bowties into its management systems & are credited with developing what we have today
A number of commercial packages available in 2000’s –BowtieXP, Bowtie Pro, Thesis etc
Significant take up outside of Oil & Gas
The Knot
Anything that has the potential to cause harm
Comes from HAZIDs, HAZOPs, structured brainstorming
Harm can be people, environment or commercial
HazardThe point in time when control over the Hazard is lost
Loss of containment, Loss of Control, Fail to Achieve
Top event
The Left Wing
Possible cause for the top event
Must show independence from other threats
Threat
The Right Wing
An unwanted event caused by the Top Event
How does the event develop and what are the potential outcomes?
Consequence
Prevention Barriers
Measure taken to prevent a threat becoming a Top Event
Barriers
Recovering from a Top Event
A measure that seeks to mitigate the consequences of a top Event
Recovery Measures
The whole bowtie
Sunday, 06 October 2013
How do they help with Risk Management?
Visual representation
WarningHumpback bridge ahead – slow your
vehicle and be prepared to stop
Text or symbols?• Traditional risk analysis output typically looks like this and it can be very
painful getting this out of a team!
06 October 2013, E.ON, Page 12
Hazard Event Effect Preventative or Corrective Measures
Anhydrous Ammonia Overfilling the receiving
tank due to lack of space
Release of ammonia liquid with the potential to
harm onsite personnel
Control PLC routes to tanks based on level
Diverse level measurement
High level alarm on each tank
High level trip shuts inlet valve
Toxic gas warning system
ESD system
Water spray system
Emergency plan
Emergency escape equipment
Text or symbols?• Same event represented in a bowtie
• My experience so far is producing a bowtie can be very engaging for a team
• Quote - I’ve never heard after a HAZOP – ‘That was really fun and I learnt a lot’ !
Zooming in
top related