3. A SCENARIO….
You and your friends are on a road trip by using a car in the middle
of the night. You were replying a text message while driving at 100
km/h and it was raining heavily. The car hits a deep hole and one of
your tire blows. You hit the brake, but due to slippery road and your
car tire thread was thin, the car skidded and was thrown off the
road.
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4. POINTS TO PONDER
What is the cause of the accident?
What is the consequence of the event?
What can we do to prevent all those things to happen in the first place?
What other possible accidents might happen on the road trip?
Can we be prepared before the accident occurs?
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5. Can we make it more systematic?
Parameter Guideword Possible
Causes
Consequences Action Safeguard
Car speed Too fast
Too slow
Rushing Skidded when
emergency brake
- Slow down
- Speed up
-ABS brake system
-Safety belt
- Air bag
Tire No thread
Less thread
Tire too old, often
speeding and
emergency break
Car skidded - Check frequently
- Have spare tire
Window
visibility
Low
Very low
Rain Cannot see the road
Car light Dim
No light
-Stop car
-Go to nearest garage
-Use emergency signal
Road With holes
Rocky
Breaks the car tire - Put a signboard
-Street lights
Travel time Night
Foggy
No street light -Travel during daylight
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6. HAZOP ?
A Hazard and Operability (HAZOP) study is a structured and systematic examination of a
planned or existing process or operation in order to identify and evaluate problems that may
represent risks to personnel or equipment, or prevent efficient operation.
A HAZOP is a qualitative technique based on guide-words and is carried out by a HAZOPteam
during a set of meetings.
A HAZOP is a process to identify and Accessrisks.
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7. Objective of HAZOP
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• For identifying cause and the consequences of perceived mal
operations of equipment and associated operator interfaces in
the context of the complete system.
• It accommodates the status of recognized design standards
and codes of practice but rightly questions the relevance of
these in specific circumstances where hazards may remain
undetected.
12. Team Members & Their
Responsibility
HAZOP team leader HAZOP secretary HAZOP team members
Responsibilities: Responsibilities: The basic team for a
1.Define the scope for the 1.Prepare HAZOP process plant will be:
analysis
2.Select HAZOPteam
members
worksheets
2.Record the discussion in
the HAZOP meetings
Project engineer
o Commissioning manager
o Process engineer
o Instrument/electrical
3.Plan and prepare the 3.Prepare draft report(s)
engineer
oSafety engineer
study
4.Chair the HAZOP
meetings
13. HAZOP meeting
Proposed agenda:
1.Introduction and presentation of participants.
2.Overall presentation of the system/operation to be analysed.
3.Description of the HAZOP approach.
4.Presentation of the first node or logical part of the operation.
5.Analyse the first node/part using the guide-words and parameters.
6.Continue presentation and analysis (steps 4 and 5)
7.Coarse summary of findings.
Focus should be on potential hazards as well as potential operational
problems.
Each session of the HAZOP meeting should not exceed two hours.
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15. HAZOP procedure
•
•
•
•
•
•
•
•
•
•
•
1.Divide the system into sections (i.e., reactor, storage)
2.Choose a study node (i.e., line, vessel, pump, operating
instruction)
3.Describe the design intent
4.Select a process parameter
5.Apply a guide-word
6.Determine cause(s)
7.Evaluate consequences/problems
8.Recommend action: What? When? Who?
9.Record information
10.Repeat procedure (from step 2)
Indrajit
Das;REC;IIT-KGP
1
5
16.
17. Causes & Consequences
Causes: The reason(s) why the deviation could occur. Several
causes may be identified for one deviation. It is often
recommended to start with the causes that may result in the
worst possible consequence.
Consequences: The results of the deviation, in case it occurs.
Consequences may both comprise process hazards and
operability problems, like plant shut-down or reduced quality of
the product. Several consequences may follow from one cause
and, in turn, one consequence can have several causes.
1
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18. Safeguards
Facilities that help to reduce the occurrence frequency of the
deviation or to mitigate its consequences. There are five types of
safeguards that:
1.Identify the deviation:
2.Compensate for the deviation:
3.Prevent the deviation from occurring:
4.Prevent further escalation of the deviation:
5.Relieve the process from the hazardous deviation.
19. • HAZOP technique is used by most major companies handling and
processing hazardous material,
- oil and gas production
- flammable and toxic chemicals
- pharmaceuticals etc
Where HAZOP is used ?
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20. 7 steps of HAZOP ?
Let’s break down a HAZOP into 7 steps:
1. Identify the Risk by asking what can cause a hazardous event.
2. Describe the consequence and assign a severity level.
3. Assess the probability of the cause.
4. Evaluate the Risk based on the severity and probability without any safeguards
5. Look up your Risk Matrix to categorize the Risk.
6. Assess the Risk with Safeguards
7. Make a decision to accept the Risk or make a recommendation to further reduce
the risk.
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21. GUIDE WORDS *
POSSIBLE CAUSES DEVIATION ( FROM DESIGN AND/OR
OPERATING INTENT )
CONSEQUENCES
ACTION(S) REQUIRED OR RECOMMENDEED
HAZOP Study Procedure
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22. Guide Words
22
NONE
MORE
No forward flow when there should be
More of any parameter than there should be,
e.g more flow, more pressure, more
temperature, etc.
LESS
PART
MORE THAN
OTHER
As above, but "less of" in each instance
System composition difference from what it
should be
More "components" present than there should
be for example, extra phase, impurities
What needs to happen other than normal
operation, e.g. start up,shutdown, maintenance
23. Guide Words
23
MORE OF
LESS OF
LESS
PART OF
MORE TEMPERATURE, pressure caused by external
fires; blockage ; shot spots; loss of control ; foaming;
gas release; reaction;explosion; valve closed; loss of
level in heater; sun.
e.g., LESS FLOW caused by pump failure; leak; scale in
delivery; partial blockage ; sediments ; poor suction
head; process turndown.
e.g., low temperature, pressure caused by Heat loss;
vaporisation ; ambient conditions; rain ; imbalance of
input and output ; sealing ; blocked vent .
Change in composition high or low concentration of
mixture; additional reactions in reactor or other
location ; feed change.
24. Guide Words
■ Impurities or extra phase Ingress of contaminants such as air,
water, lube oils; corrosion products; presence of other process
materials due to internal leakage ; failure of isolation ; start-up
features.
■ Activities other than normal operation start-up and shutdown of
plant ; testing and inspection ;
■ sampling ; maintenance; activating catalyst; removing blockage or
scale ; corrosion; process emergency ; safety procedures
activated ; failure of power, fuel, steam , air, water or inert gas;
emissions and lack of compatibility with other emission and
effluents.
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MORE THAN
OTHER
25.
26.
27.
28. HAZOP Study Form
28
Sheet 1 of
HAZOP STUDY REPORT FORM
TITLE :
LINE 1 :
CAUSES
DEVIATION
CONSEQUENCES EXISTING PROVISIONS ACTIONS, QUESTIONS OR
RECOMMENDATIONS
29. HAZOP Study
29
HAZOP study are applied during :
• Normal operation
• Foreseeable changes in operation, e.g. upgrading, reduced
output, plant start-up and shut-down
• Suitability of plant materials, equipment and instrumentation
• Provision for failure of plant services, e. g . steam, electricity,
cooling water
• Provision for maintenance.
31. Preli minary HAZOP Exampl
e
31
T
C
Cooling Coils
Monomer
Feed
Cooling Water to Sewer
Cooling
Water In
Thermocouple
Refer to reactor system shown.
The reaction is exothermic. A cooling system is
provided to remove the excess energy of reaction.
In the event of cooling function is lost, the
temperature of reactor would increase. This would
lead to an increase in reaction rate leading to
additional energy release.
The result could be a runaway reaction with
pressures exceeding the bursting pressure of the
reactor. The temperature within the reactor is
measured and is used to control the cooling water
flow rate by a valve.
Perform HAZOP Study
32. Prel i minary HAZOP
on
32
React or -
Causes Action
Guide Word
NO
Deviation
No cooling
Exampl e
Consequences
Temperature increase
in reactor
REVERSE Reverse cooling
flow
Failure of water
source resulting in
backward flow
MORE More cooling
flow
Instruct operators
on procedures
AS WELL AS Reactor product
in coils
Check maintenance
procedures and
schedules
OTHER THAN Another
material besides
cooling water
Water source
contaminated
33. Prel i minary HAZOP
on React or –
Answer
Deviation Causes Consequences Action
33
Guide Word
NO No cooling Cooling water valve
malfunction
Temperature increase in
reactor
Install hightemperature
alarm (TAH)
REVERSE Reverse cooling
flow
Failure of water source
resulting in backward
flow
Less cooling, possible runaway
reaction
Install check valve
MORE More cooling flow Control valve failure,
operator fails to take action
on alarm
Too much cooling, reactor cool Instruct operators on
procedures
AS WELL AS Reactor product
in coils
More pressure in reactor Off-spec product Check maintenance
procedures and
schedules
OTHER THAN Another material
besides cooling
water
Water source
contaminated
May be cooling inefffective
and effect on the reaction
If less cooling, TAH will
detect. If detected, isolate
water source. Back up
water source?
34. HAZOP - Hazard and Operability
34
Nodes
Parameters
Guide
words
Consequence
Deviation
All of these terms! This stupid table!
I hate HAZOPS. Why don’t we just
learn the engineering?
ATTITUDE CHECK
36. 57
HAZOP - Hazard and Operability
Without HAZOP
How will you focus all
members of a team on the
key issues in a systematic
manner?
You are
responsible for
the safety team.
