This document provides an overview of bowtie diagrams and how they are used for risk management. It discusses the origins of bowtie diagrams, which evolved from cause-consequence diagrams. Bowtie diagrams visually represent hazards, threats, consequences, and prevention/recovery barriers on a diagram shaped like a bowtie. They provide a clear visual representation of risk that can be more engaging for teams to discuss than traditional text-based risk analysis outputs. The document notes that bowtie diagrams have significant usage outside of oil and gas and that commercial software is available to create them.

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Bowties – a visual view of Risk
World Class Process Safety Management for Power Generation

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Overview of bowties

3. 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 Hazan
course 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

4. The Knot
Anything that has
the potential to
cause harm
Comes from
HAZIDs, HAZOPs,
structured
brainstorming
Harm can be
people,
environment or
commercial
Hazard The point in
time when
control over the
Hazard is lost
Loss of
containment,
Loss of Control,
Fail to Achieve
Top
event

5. The Left Wing
Possible cause
for the top
event
Must show
independence
from other
threats
Threat

6. The Right Wing
An unwanted
event caused by
the Top Event
How does the
event develop and
what are the
potential
outcomes?
Consequence

7. Prevention Barriers
Measure taken
to prevent a
threat becoming
a Top Event
Barriers

8. Recovering from a Top Event
A measure that
seeks to mitigate
the consequences
of a top Event
Recovery
Measures

9. The whole bowtie

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How do they help with Risk
Management?

11. Visual representation
Warning
Humpback bridge
ahead – slow your
vehicle and be prepared
to stop

12. 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

13. 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’ !

14. Zooming in