Risk Management in HighHazard Industries
Bow-Tie Diagrams
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Technical Safety – Process Safety – Functional Safety
Risks and Their Management
Dropped Objects
Security
Helicopter Crash
Process Safety Incident
Marine Vessel Collision
Loss of Stability
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Risk management at the plant is intended to reduce the
likelihood and severity of major accidents
This occurs though:
•
Identification of the hazards and risks
that exist on the facility
•
Understanding the potential
consequences if an event occurs
•
Awareness of the barriers that are in
place to keep the plant safe
•
Knowing how to respond in the event of
an emergency
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The basic concepts of barrier bow-tie analysis and the risk
matrix
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Why do we use a risk matrix?
Probability
To inform where our
focus/priorities should be
Severity
It visually displays the
ranking of risks, how
probable an incident is to
occur versus the severity of
the consequence
Low
Medium
High
Highest
Risk
High
Medium
Low
Lowest
Risk
An example of a risk matrix
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The concept of inherently safer design
• Where possible eliminate the risk
completely, e.g. buildings not in
blast zone, use instrument air
rather than gas, no source of
ignition present.
• This lowers the risk ranking
• Design in as early as possible
• Procedural barriers are less
reliable
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What is a bow-tie barrier and how is it used?
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The bow-tie barrier model has several components…
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The center of the bow-tie is the hazard and the risk event
The ‘hazard’ is the thing that can
cause harm (e.g. pressurised
hydrocarbons, electricity, height)
The ‘event’ is the release of the
hazard (e.g. loss of containment,
collision, structural collapse)
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On the left hand side of the bow-tie are the causes
The ‘cause’ is the possible way of
initiating the ‘event’
(e.g. corrosion, erosion, dropped object, 3rd party
action)
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On the right hand side of the bow-tie are the consequences
The ‘consequence’ is the possible negative
outcome resulting from the ‘event’
(e.g. environment damage, major fire, injury to people, regulator
action)
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When we cannot eliminate the risk, barriers are put in
place to prevent or mitigate the hazardous event
These barriers are
intended to prevent the
risk event from occurring
(e, g. mechanical integrity, relief
valve, ESD system)
These barriers are intended to
mitigate the consequences and
reduce the severity if the event
occurs
(e.g. ignition prevention, fire & gas systems,
evacuation procedure, spill containment)
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3 types of barriers…
Passive:
• No activation required
reliability
• e.g. mechanical integrity of a pipe, paint coatings to
prevent corrosion, a fire wall
Active:
Protective
Coatings
• Needs activation but can be an automated system
• e.g. a relief valve, control system, fire suppression
system
Procedural:
• Needs activation but by a person doing a critical task
Control Room
• Supported by critical procedures
• e.g. alarm response, evacuation, spill response
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One healthy barrier can directly stop a risk event from
occurring, even when others fail
Corrosion
Paint coating
Stopped!
Corrosion Monitoring
Emergency Shutdown Systems
Evacuation process
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but barrier degradation are like holes, allowing the risk
event to occur, resulting in an incident
Corrosion
Paint coating
Corrosion Monitoring
Emergency Shutdown Systems
Evacuation process
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Barriers need to be maintained and inspected routinely to
verify effectiveness
•
Understanding the health of the
barriers is critical to understanding the
vulnerabilities
•
Barriers require proactive maintenance
and inspection to maintain
functionality
•
Operators must have the discipline to
follow up when something does not
look right
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Bow Tie Barrier example - Offshore LOPC
(Dave King- BP)
Note: colours above barriers are just
examples of barrier health. This could
show where certain Cause legs are
vulnerable
Bow Tie Barrier Model - Offshore LOPC
(Dave King- BP)
Process Plant
3.1
Hydrocarbons
Note: colours above barriers are just
examples of barrier health. This could
show where certain Consequence legs are
vulnerable
Bow Tie Barrier Model - Offshore LOPC (Dave King- BP)
Note: colours above barriers are just
examples of barrier health. This could
show where certain Cause and
Consequence legs are vulnerable
Acknowledgements
These slides are based on the presentation of
Dave King of BP.
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