1. Bowtie Analysis – An Effective Risk Management
Hindustan Petroleum Corporation Limited
Corporate HSE Department By
Murthy V S S Malyala
Manager –HSE

2. Contents Risk analysis –background Incidents in Oil Industry
Bowtie – a visual risk evaluation tool
Terminology
Development of Bowtie
Case study – Gas fired Pipe heater explosion modelling
Barriers for controlling incidents
Barrier Effectiveness
End users of Bowtie
Better than other Hazard identification Techniques

3. Risk Analysis
Risk = Probability X Consequence

4. Vapor cloud explosion ( Explosion during start up)
Decades of learning from disasters
3000 fatalities
MIC Release
500 fatalities and terminal destroyed
Rupture of 8 inch LPG pipeline
167 fatalities and platform destroyed.
28 fatalities and 36 injured
Leakage from pump discharge relief valve
Bhopal Gas Incident- 1984
Vapor cloud explosion ( Explosion during start up)
Mexico (1984)
18 fatalities and 81 injured
LPG Leakage –
Sampling/ water draining
Flixborough (1974)
Piper Alpha 1988
Loss – Human & Property
Feyzin, France
Emergency Preparedness
MOC
Staffing
Multiple Failures
Work permit system
Hazard communication
Operating Procedure
Assert Integrity
Management Of Change
Years of learning

5. Decades of learning from disasters
Leakage occurred during maint. work on valve.
overfilling of a large storage tank
Fatalities 23. Over 130 injured
Over filling of column.
Jaipur
Terminal
(2009)
Fatalities 15. Over 170 injured
Pasadena 1989
Buncefield (2005)
Catastrophic failure of heat exchangers
Loss – Human & Property
2 fatalities and 8 injured
BP Texas (2005)
Esso Longford (1998)
Operating Discipline
Contractor Safety
Maintenance practices
Operating Discipline
Hazard Analysis
Assert Integrity
Years of learning

6. Bowtie Analysis
The Bow-tie Diagram is a user-friendly, graphical illustration of how hazards are controlled.
Bowtie …. A simplified fusion of
Fault Tree Analysis and Even Tree Analysis
FTA + ETA = Bowtie
Effective risk management is only possible if people are assigned responsibilities for controls via HSE-Critical Tasks
Visible links are made to HSE-critical systems and competencies
Bowtie methodology demonstrates not only what controls are in place today and their effectiveness
Used in Oil & gas , Aerospace, Railways

7. Bowtie analysis for high risk Activities
ALARP

8. Bowtie Analysis

9. Bowtie Analysis

10. Terminology
Top event - no catastrophe yet but the first event in a chain of unwanted events.
Threats - The top event can be caused by (sufficient or necessary causes).
Consequences - The top event has the potential to lead to unwanted consequences.
Barriers - Preventive or mitigate measures taken to prevent threats from resulting into the top event.
Escalation factor - a condition that defeats or reduc es the effectiveness of a barrier.

11. Bowtie analysis – Development
Describe unwanted event for the Bowtie Knot
Determine scope of analysis – operational boundries
Identify threats that could cause the event
Identify possible consequence of the event
Select the optimum set of control to manage the causes and consequence of the event
Identify failure mode for important control
Determine items for control assurance management

12. Case Study - Simple Pipe still Heater

13. Case Study – Gas fired Pipe Heater Explosion
Threats
Consequence

14. Threats Preventive Barriers Unwanted Event

15. Threats Preventive Barriers Unwanted Event

16. Threats Preventive Barriers Unwanted Event

17. Threats Preventive Barriers Unwanted Event

18. Top event Mitigation barriers Consequence

19. Complete Bowtie Diagram

20. Swiss cheese model –Hazard -Barriers– Incident

21. Barriers in accident prevention

22. The Hierarchy of Hazard Control Methodology

23. Increased reliability
Barrier system
Increased reliability
1. Accountability
2. Detect – Decide - Act
3. Safety Critical Task
4. Safety Critical Equipment

24. Simple application - Bowtie - Car Incident

25. Organisations manage risk using ‘barriers’
Swiss cheese model
Organisations manage risk using ‘barriers’
Barriers – use of equipment, design of plant (redundancy, overflows, etc.), following rules, procedures, standards …… usually barriers are people doing a job
Barriers are ‘functions’
Why incidents happen .

26. Why do barriers fail? & Weakness in Incident causation path
Underlying causes
Preconditions
Immediate causes
Creates
That influences the person
To take action or inaction
That causes barriers to fail
That result in
Accidents, incidents and business upsets
An organisation
Error / violation promoting conditions
SMS
Leadership
Culture
Performance influencing factors (PIFs)
Competence
Fatigue
Environment
Supervision
Task
Etc.
Human action or inaction
slips, lapses, mistakes, violations
- Human and Organisational Factors

27. Types of Barrier in Bowtie
1. Detect – Decide - Act 2. Safety Critical Equipment  3. Safety Critical Task 4. Accountability

28. End users of Bowtie Analysis
Bow tie is Visual risk depiction tool for a failure mode situation
Technician – Look for Hardware controls –active & passive
Supervisor – Look for administrative controls - Health of controls
Manager - Identify weak links in controls & monitor Sustained Operational discipline & timely maintenance & Skill development.

29. Thanks

30. Questions?

32. HAZARD IDENTIFICATION Techniques
Commonly used :
HAZOP- Identifies “process plant” type incidents(time consuming)
What If Analysis- Possible outcomes of change(high dependency of skills)
FMEA/FMECA-Equipment failure causes (Extremely time consuming)
Task Analysis-(JSA ) Maintenance etc, incidents (Does not address process deviations
Fault Tree Analysis-Combinations of failures(identified the incident first& difficult to update )
Checklists-questions to assist in hazard identification(no new hazard types are identified)
HAZAN -Risk ranking tools are used Dow index OR MOND index