hazard analysis

1. HAZOP
(Hazard Operability)

2. HAZOP Objective
 A hazard and operability study (or HAZOP) is a systematic,
critical examination by a team of the engineering and
operating intentions of a process to assess the hazard potential
of mal-operation or mal-function of individual items of
equipment and the consequential effects on the facility as a
whole.
 The HAZOP technique was initially developed to analyze
chemical process systems, but has later been extended to other
types of systems and also to complex operations and to
software systems.

3. Origin of HAZOP Study
 HAZOP were initially 'invented' by ICI in the United Kingdom, 1963
 HAZOP started to be more widely used within the chemical process
industry after the Flixborough disaster (UK) in 1974 that killed 28
people and injured scores of others.
 The system was then adopted by the petroleum industry, which has a
similar potential for major disasters.
 This was then followed by the food and water industries, where the
hazard potential is as great, but of a different nature, the concerns
being more to do with contamination rather than explosions or
chemical releases.
 International Standard IEC61882 (HAZOP Studies Application Guide
2001

4. When to perform a HAZOP ?
 HAZOP studies may also be used more extensively,
including: At the initial concept stage when Design
Drawings are available.
 When the final Piping And Instrumentation
Diagrams (P&ID) are available.
 During construction and installation to ensure that
recommendations are implemented.
 During commissioning.
 During operation to ensure that plant emergency and
operating procedures are regularly reviewed and
updated as required.

5. Types of HAZOP
 Process HAZOP
The HAZOP technique was originally developed to
assess plants and process systems
 Human HAZOP
A “family” of specialized HAZOPs. More focused on
human errors than technical failures
 Procedure HAZOP
Review of procedures or operational sequences
 Software HAZOP
Identification of possible errors in the development
of software

6. Prerequisites for HAZOP
As a basis for the HAZOP study the following information should
be available:
 Process flow diagrams
 Piping and instrumentation diagrams (P&IDs)
 Layout diagrams
 Material safety data sheets
 Provisional operating instructions
 Heat and material balances
 Equipment data sheets Start-up and emergency shut-down
procedures

7. HAZOP Procedure
 Divide the system into sections (i.e., reactor, storage)
 Choose a study node (i.e., line, vessel, pump, operating
instruction)
 Describe the design intent
 Select a process parameter
 Apply a guide-word
 Determine cause(s)
 Evaluate consequences/problems
 Recommend action: What? When? Who?
 Record information
 Repeat procedure (from step 2)

8. HAZOP TERMINOLOGIES
 Parameter
The relevant parameter for the condition(s) of the process
(e.g. pressure, temperature, composition).
 Deviation
A deviation is a way in which the process conditions may
depart from their design/process intent.
 Node
A node is a specific location in the process in which (the
deviations of) the design/process intent are evaluated.
Examples might be: separators, heat exchangers,
scrubbers, pumps, compressors, and interconnecting
pipes with equipment.

9.  Design Intent
The design intent is a description of how the process is
expected to behave at the node; this is qualitatively
described as an activity (e.g., feed, reaction,
sedimentation) and/or quantitatively in the process
parameters, like temperature, flow rate, pressure,
composition, etc.
 Guideword
A short word to create the imagination of a deviation of
the design/process intent. The most commonly used set
of guide-words is: no, more, less, as well as, part of, other
than, and reverse.
Guide-word + Parameter
Deviation

13. A scenario…
Someone on a road trip by using a car in the middle of the
night. A boy 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. He hit the brake, but due to
slippery road and his car tire thread was thin, the car
skidded and was thrown off the road.

14. 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?

15. Can we make it more
systematic?
Parameter Guideword Possible
Causes
Consequences Action Safeguard
Car speed Too fast Rushing Skidded when
emergency
brake
- Slow down -ABS brake
system
-Safety belt
- Air bag
Tire No thread
Less thread
Tire too old,
often
speeding
and
emergency
break
Car skidded Change tire - Check
frequently
- Have spare
tire
Window
visibility
Low
Very low
Rain Cannot see the
road

16. T
C
Cooling Coils
Monomer
Feed
Cooling Water to Sewer
Cooling
Water In
Thermocouple
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

18. HAZOP Study (Flash Drum)