Objectives of the hazard Identification and Assessment
- Assure hazards are known, understood & properly managed
- Risk is reduced to As Low As Reasonably Practicable (ALARP)
Why accidents still happen despite hazard identification and assessment being done?
How do you manage risk?
- Identify hazards & potential effects – Know and understand the hazards
- Prevent, mitigate and recover from the hazardous events -Manage the hazards
Identification of the Hazards and Potential Effects
Knowing and understanding Hazards
- What are sources of the hazard?
- What hazardous event (top event) could potentially occur when a hazard is released?
- What could release the hazard & cause the top event to occur? What are the ”threats”?
- What are the consequences from the top event? How severe will the consequences be?
Prevention, Mitigation & Recovery
Managing hazards
- How to avoid the threats(or causes)? – prevention or threat barriers
- How to avoid or minimise the consequences – mitigation or recovery barriers
Only possible if hazards are known & understood
- All hazard are identified
- The threat (causes) & consequences of top events are known
Managing Hazards – Risk Reduction
Hazard Identification
You Must Get It Right
- Having done hazard identification or assessment does not guarantee safety
- Many accidents occurred despite having done hazard identification or assessment
- Why?
- [1]Failure to identify hazards
- [1]Failure to manage hazards effectively
Doing it is not enough, you must get it right
How Do You Get It right?
Identification of the hazards & potential effects must be complete
- All relevant hazards must be identified
- Threats (causes) & consequences identification (hazard) analysis must be comprehensive
Threat barriers (prevention) & mitigation or recovery barriers must be adequate
- They must be known to be or confirmed effective
- Supported by the risk assessment to determine ALARP
Bow Tie Methodology …… the Solution
- Simple and pragmatic approach
- Empphasis on the effectiveness of the risk reduction measures
- Effective visualisation
- Allows better communication of the hazards
- Can be applied for all types of the hazards
- Increasingly becoming the preferred techniques by the regulatory bodies and leading companies
- Efficiently aided by user-friendly softwares
Bow Tie Methodology
- Originated as a technique for developing a “Safety Case” in the Oil and Gas Industry, post the Piper Alpha Incident in the year 1988
- By linking ‘Hazards’ and ‘Consequences’ to an ‘Event’ it is possible to develop the relationship to include the causes, or ‘Threats’, & the ‘Prevention’ and ‘Recovery Measures’
- Further understanding can be gained by examining the means by which these defenses can fail, & identifying the key components which demonstrate the integrity of these controls
- Documents & Procedures
- Control Types & Effectiveness
- Critical Equipment & Systems
- Tasks & the persons behind the Tasks
Bow Tie Connections
Bow-tie technique diagrammatically represents hazardous events in such a way to easily show the connections between hazards or threats & their consequences
Bow Tie Concept
Bow Tie Terminology Definitions
- Hazard – Potential source of harm to people, assets, the environment & company reputation
- Top Event – The incident that occurs when the hazard is realized
- Threats – What could cause the top event to occur?
- Consequences – What could happen if the top event occurs?
- Barrier – What directly prevents or reduces the likelihood of the threat?
- Recovery Measure – What prevents, minimizes or helps recovery from the consequence?
- Escalation Factor – What could avert the barrier or recovery measure from working as intended?
- Escalation Factor Control – What averts or minimizes the chance of the barriers or recovery measures becoming Ineffective?
Bow Tie Analysis Steps
Major Hazard Classification
Bow Ties are generally developed for only for Major Hazards – defined using Risk Assessment Matrix
Typical Major Hazards
- Hydrocarbons – fires/explosions/blowouts/oil spills
- Toxic materials – toxic releases
- Air/marine/land transport – helicopter/boat/road accidents
- Shipping activities – marine collision
- Object under load (structure) – structural failure
- Lifting operations – dropped objects
Managing Barrier Effectiveness –Relating Critical Activities to Barriers
Typical Major Hazard Barriers
- Structures (jackets/decks) – preventive barriers
- Hydrocarbon containment – preventive barriers
- Chemical injection systems – preventive barriers
- Relief systems – preventive barriers
- Fire, gas & smoke detectors – recovery barriers
- Ignition control – recovery barriers
- Shutdown systems – preventive/ recovery barriers
- Active & passive fire protection systems – recovery barriers
- Firewater pumps & ringmain – recovery barriers
- Emergency response equipment – recovery barriers
- Emergency communication & power – recovery barriers
- Escape, evacuation & rescue provisions – recovery barriers
- Life/survival equipment – recovery barriers
Bow Tie Allows Optimised Integrity Assurance
Use of Bow Tie for Effective Control of Major Hazard
Inputs to Barrier Effectiveness Assessment
- Design standards
- Inspection or maintenance records
- Test performance results
- Asset integrity reporting
- Processes & procedures
- Audit findings
- Incident investigation findings
- Personnel competency
Barrier Effectiveness Assessment –Example
Bow Tie vs Other Methods ?
- Many other ‘risk techniques’ – where does Bow Tie fit in ?
- A Management System tool which takes its knowledge from various sources to represent the ‘risk picture’ in a logical & usable format.
- Not intended as a replacement for any particular method
