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