1. Process Safety in Chemical Plants with Focus on HAZOP
Title: HAZOP in Practice
09-10 December 2008
Second World Congress on Disaster Management
Process Safety in Chemical Plants with Focus on HAZOP by
S. S PIPARA
Faculty at AVVIARE Educational Hub, Noida
and
Ex. Joint President GRASIM Industries Ltd., Nagda (India)
Chilworth Safety & Risk Management P. Ltd.

2. Process Safety Management
Root cause analysis of incidents
The hazards associated with Unit processes and Unit operations
Process Safety and Equipment Health

3. Hazard Identification Techniques
Techniques in use are in one of three categories:
Techniques 1 2 3
Experience Based
Checklists and What-If / Checklists
Indices and Layers of Protection Analysis (LOPA)
Analytical
Failure Mode and Effects Analysis (FMEA)
Fault Tree Analysis and Event Tree Analysis
Creative
Brainstorming
HAZOPS

4. Definitions Process Hazard Analysis Catastrophic Release
An organized and systematic effort to identify and determine the significance of the hazards associated with the handling and processing of highly hazardous chemicals and assess the effectiveness of safeguards.
Catastrophic Release
Major uncontrolled emission, fire or explosion that causes serious danger to employees in the workplace
Highly Hazardous Chemical
a substance that has toxic, flammable, explosive or reactive properties.
Process
Any activity including use, storage, manufacturing, handling or on-site movement of a highly hazardous chemical
Safeguard
Procedures and devices used to control process hazards and manage risk.
Preventions
Procedures and devices intended to stop the initiation of an undesired event or interrupt the escalation of an event sequence.
Mitigations
Procedures and devices intended to respond to events and reduce the magnitude of undesired consequences.

5. Experience Based Hazard Identification Techniques
Title: HAZOP in Practice
09-10 December 2008
Experience Based Hazard Identification Techniques
Checklist
What-If/ Checklist
Natural extension of simple checklist
Begins to introduce a customization of the checklist to better fit the process
Best if done by experienced personnel
Most effective in early design stage of new projects.
Most often guided by a checklist of topics
Can be applied to a limited scope
Individual (of most limited value)
Informed Individual (safety specialist)
Outside standards such as:
Center for Chemical Process Safety (CCPS)
National Fire Protection Association (NFPA)
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6. What-If Spreadsheet Example
Process Upset
Causes
Consequences
Safeguards
Action Items
What if sample is spilled on operator
Bottle breaks
Operator error
Operator burned, LTI
  Procedures and training
PPE
Modify procedures to stress issue
What if batch temperature is too high?
Control failure
No issue, material is thermally stable
Procedures and training
DCS
What if reactor leaks?
Corrosion
Maintenance Error
Clean up costs only
PM Program
ERP
 Ensure adequate spill clean up materials are on hand
What if spill ignites and pool fire occurs indoors?
Leak plus spark from equipment
Operator fatality possible
  Big $$$ loss
Fixed Sprinklers
Adequate drainage
Ensure adequate PM of electrical devices
Note: Action items are often abbreviated during the review and expanded to include
additional explanation in the final report.

7. Fault Tree Analysis Analytical Hazard Identification Techniques
Title: HAZOP in Practice
09-10 December 2008
Analytical Hazard Identification Techniques
Fault Tree Analysis
Use of a logic diagram to plot the path from an undesired outcome back to the basic equipment, systems and human failures, the Basic Events;
Predominantly used for high consequence, low frequency events, to determine the adequacy of safeguards;
Graphical representation of the combination of faults leading to a predefined undesired event
This methodology uses logic gates to show all the credible paths from where the undesired event could occur
A top down approach where each level is required to allow the next;
The analyst asks what is required for the upper event or condition to exist?
The pathway is plotted on the diagram using standard symbols
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8. Basic Fault Tree And Bad Consequences Likelihood = FxP Initiating
Event(s)
Failure of
Protective
Systems
Frequency = F
Probability
of Failure
on Demand
= P
Community ERP
Site ERP
2nd Containment
ERS
SIS
Auto Shutdown
Alarms/Intervention
Process Control
Procedural Checklist
Procedures/Training
Mech Design/PM
Process Design
Equipment failure:
Corrosion
Fabrication error
Design error
Fire Exposure
Collision
Operator error
Maintenance error

9. Title: HAZOP in Practice
09-10 December 2008
Event Tree Analysis
An event tree is a graphical representation of the logic model that identifies and quantifies the possible outcomes following an initiating event.
Use of a logic diagram to plot the path from a single initiating event through each decision point where consequences can be altered to arrive at the final potential consequence. At each decision point success or failure diverts the path.
Event trees are used to identify the various accidents that can occur in a complex process
Can be used with FMEA to develop safety oriented mechanical integrity programs.
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10. Event Tree Analysis Example Quantified
Incident development path
Outcome Frequency
YES 50%
Vapor Cloud
Explosion
0.5%
YES 10%
NO 50%
Pool Fire
0.5%
Flammable
Liquid is
Released
Delay?
NO 10%
Reportable
Environmental
Incident
NO 90%
9.0%
Ignition?
Minor in-house
incident
YES 90%
90%

11. Failure Mode Effect Analysis
Title: HAZOP in Practice
09-10 December 2008
Failure Mode Effect Analysis
Failure Modes and Effects Analysis (FMEA) is methodology for analyzing potential reliability problems early in the development cycle where it is easier to take actions to overcome these issues, thereby enhancing reliability through design.
FMEA is used to identify potential failure modes, determine their effect on the operation of the product, and identify actions to mitigate the failures.
An assessment of equipment, components and systems to determine the way in which failures can occur and the consequences of component failure on systems and units.
Most often qualitative but a quantitative assessment can be made.
A “Bottom Up” approach
Spreadsheet style documentation
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12. FEMA Title: HAZOP in Practice 09-10 December 2008
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13. Selecting a Hazard Identification Technique
Title: HAZOP in Practice
09-10 December 2008
Selecting a Hazard Identification Technique
Considerations
Information available
Project stage
Personnel requirements
Personnel skill level
System complexity
System type
Schedule and time restrictions
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14. Selecting Technique Title: HAZOP in Practice 09-10 December 2008
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15. Creative Hazard Identification Techniques Brainstorming
Title: HAZOP in Practice
09-10 December 2008
Creative Hazard Identification Techniques
Brainstorming
An unstructured technique used by a team to gather all ideas about a topic, without specific analysis of those ideas.
The scribe will typically write down all that is said by the team members for later analysis. (Flip Chart)
May be leader or checklist driven:
“How can the pump fail?”
Common method within a PHA team
The classic method encourages free thinking and creativity, no idea is turned away.
Only after the team’s brainstorming has reached a logical end, are documented ideas analyzed, and possibly discarded.
Brainstorming can be a good way of encouraging team participation.
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16. HAZOP - HAZard & OPerability
Title: HAZOP in Practice
09-10 December 2008
HAZOP - HAZard & OPerability
First developed at ICI in the UK in 1964 this method is a natural extension of standardized checklists.
Where checklists count on past experience, HAZOPs develops ‘synthetic experience’ by hypothesizing deviations from desired performance.
Most applicable to new and novel processes where experience is lacking.
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17. HAZOP - HAZard & OPerability
Title: HAZOP in Practice
09-10 December 2008
HAZOP - HAZard & OPerability
The basic premise of HAZOPS is:
All hazardous material incidents are instigated by a deviation from the desired operating state or condition.
If we can predict all deviations and analyze them before we operate a new process then we can head off the undesired consequences.
Forewarned is Forearmed
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18. HAZOP Approach Define Intended Process Repeat Parameter + Guided words
Deviation Cause
Consequence
Safeguard
Action
Define Intended Process
Repeat

19. Title: HAZOP in Practice
09-10 December 2008
HAZOP APPROACH
Intention:
The Intention defines, How the selected section/unit is expected to operate
Parameters:
Aspects of a process that describe it physically or in terms of what is happening
Some Parameters:
Flow
Pressure
Temperature
Level
Phase
Viscosity
Concentration
Loss of containment is a critical consideration and must be included.
Flow Rate
Flow Amount
Agitation
Aging Ph
Conductivity
Catalyst Activity
Time
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20. Title: HAZOP in Practice
09-10 December 2008
HAZOP APPROACH
Guidewords:
These are simple words, which are used to qualify the intentions in order to guide and stimulate the thinking process and so discover deviations.
Some Guidewords:
No/None
More
Less
Reverse
Other than
As well as
Part of
More = High for example High Pressure, High Temp etc.
Similarly, Less = Low
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21. HAZOP APPROACH Guideword Meanings
Title: HAZOP in Practice
09-10 December 2008
HAZOP APPROACH Guideword Meanings
Guideword
Meaning
Example
Parameter: Flow
No/None
None of design intent is achieved
No Flow
More
Quantitative increase in a parameter
More Flow
Less
Quantitative decrease in a parameter
Less Flow
Reverse
Logical opposite of the design intent occurs
Reverse Flow
Other than
Complete substitution – another activity takes place
Boiling
As well as
An additional activity occurs
Chemical Reaction
Part of
Only some of the design intent is achieved
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22. Title: HAZOP in Practice
09-10 December 2008
HAZOP APPROACH
Deviations:
Deviation means departure from the design intent
These are discovered by systematically applying the guidewords
Causes:
Reasons for deviations
Consequences:
Results of deviations
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23. Title: HAZOP in Practice
09-10 December 2008
HAZOP APPROACH
Safeguards:
Procedures or devices exists to control causes or mitigate consequences
Prevention measures or
Mitigation measures or
Combination of both
Chilworth Safety & Risk Management P. Ltd.

24. Title: HAZOP in Practice
09-10 December 2008
HAZOP APPROACH
SUMMARY
HAZOPS uses a standard list of “Guidewords” as modifiers to process Parameters to hypothesize Deviations from the desired intent.
Deviation = Guideword + Parameter
The Deviations are analyzed by the team to determine if a hazardous condition would occur, or if an important operating upset is discovered.
Chilworth Safety & Risk Management P. Ltd.

25. Title: HAZOP in Practice
09-10 December 2008
HAZOP APPROACH
SUMMARY
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26. Title: HAZOP in Practice
09-10 December 2008
HAZOP Study Team
Leader
Instrumentation
supervisor
Operator
Chemist
Chemical Engineer
Maintenance
Supervisor
Specialist
Operations
Design Team
Member
Common Team Size:
4-7 people
Scribe
It is important to select right composition of HAZOP team.
Chilworth Safety & Risk Management P. Ltd.

27. Hazard Studies
HAZID - To identify hazards and potential accident scenarios
 to be performed at the initial stage of a project
HAZOP - To identify specific hazards arising from process deviation, to evaluate adequacy of existing safeguards and to identify additional mitigating measures
 to be performed at different stages throughout the entire project life
QRA - To assess personnel risk posed by potential hazard scenarios
 to be performed at the initial stage of the project with further updating at a later stage /

28. Risk Identification Techniques
Identifying the Risk
Risk Identification Techniques
When you might use them
Safety Review
Checklist
Preliminary Hazard Analysis
What-If
Abbreviated HAZOP Study
Used in preliminary hazard evaluation studies to provide a general overview of existing risks
(Usually not too time consuming)
What-If/Checklist
Detailed and complete HAZOP Study
Failure Mode and Event Analysis
Used to develop a more detailed analysis of potential risks
Fault Tree Analysis
Event Tree Analysis
Cause Consequence Analysis
Human Reliability Analysis
Used in conjunction with quantitative risk analysis to establish a high level detail about risks
(Usually used for specific area or Unit Operations)

29. Hazard identification Scenario identification
Risk Assessment Procedure
HAZARD IDENTIFICATION METHODS:
- Process hazard checklist
- Hazard survey: DOW index
- HAZOP hazard & operability study
- Safety review
System description
Hazard identification
Scenario identification
Accident
probability
consequences
Risk determination
Risk &
Hazard
acceptable ?
Modify design
Accept system Y N
RISK ASSESSMENT:
- What can go wrong & how ?
- What are the chances ?
- Consequences ?
EXTREMES
- Low probability
- Minimal consequences

30. THANKS