This document discusses Hazard and Operability Studies (HAZOP). It provides an overview of the HAZOP methodology, including that it involves a team systematically using guidewords to identify deviations from the design intent and their potential causes and consequences. The document also gives examples of applying the HAZOP technique to analyze specific components, like conducting a HAZOP study on a shell and tube heat exchanger using relevant guidewords. Overall, the HAZOP method aims to identify hazards as well as operability problems for improved safety and operations.

2. HAZOP

3. Safety sampling
Safety survey
Risk assessment
Safety inspection
Job safety analysis

4.  Hazards and Operability (HAZOP)
 Fault Tree Analysis (FTA)
 Failure mode-and-effect analysis (FMEA)
 Safety audit

5. “A systematic study, carried out by a team of
persons experienced in aspects of the
topic , using the line by line (or step by
step) application of guidewords to identify
all deviations from the design intent with
undesirable effects for safety, operability or
the environment.”Some “truths” emerge
which are not always appreciated.

6. HAZOPs concentrate on identifying both
hazards as well as operability problems.
Although hazard identification is the
main focus, operability problems should
be identified to the extent that they
have the potential to lead to process
hazards, result in an environmental
violation or have a negative impact on
profitability.

7.  Hazard - any operation that could possibly
cause a catastrophic release of toxic,
flammable or explosive chemicals or any
action that could result in injury to
personnel.
 Operability - any operation inside the design
envelope that would cause a shutdown that
could possibly lead to a violation of
environmental, health or safety regulations
or negatively impact profitability.

8. HAZOP Study
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
• failure of plant services, e. g . steam, electricity, cooling
water
• maintenance.

9.  Design or Project Engineer
Process Engineer
Commissioning Manager
Instrument Design Engineer

10.  Plant Superintendent
 Process Engineer
 Maintenance Engineer
 Instrument Engineer
 Technical Engineer

11.  No or None
 More
 Less
 As well as
 Part of
 Other than
 Reverse

12. Guide Word Deviation Example Interpretation
NO or NONE No part of the intention is achieved No forward flow when there should be.
MORE Quantitative increase in a physical Higher pressure, flow rate, temperature...
property (rate or total quantity) Quantity of material is too large.
LESS Quantitative decrease in a physical Lower pressure, flow rate, temperature...
property (rate or total quantity) Quantity of material is too small.
MORE THAN All intentions achieved, but with Impurities in flow (air, water, oil...)
or AS WELL AS additional effects (qualitative Chemicals present in more than one phase
increase) (vapour, solid)
PART OF Only some of the intention is One or more components of mixture
achieved (qualitative decrease) missing, or ratio of components is incorrect
OTHER THAN A result other than the intention is Unusual circumstances etc... see next slide
achieved
REVERSE The exact opposite of the intention Reverse flow.
is achieved

13. • A Piping and Instrumentation Diagram -
P&ID, is a schematic illustration of
functional relationship of
piping, instrumentation and system
equipment components.
• P&ID represents the last step in process
design.
• P&ID shows all of piping including the
physical sequence of
branches, valves, equipment, instrumentat
ion and control interlocks.

14. Choices of lines – P&ID must be divided logically.
Not too many sections. Factors to be considered :
 Each section should contain active components, which
gives rise to deviations.
Ex: piping which contains control valves can give rise
to flow deviations, heat exchangers can cause
deviations.
section – contain significant amount of
 Materials in
hazardous materials.
 Sectionbased on process and states of materials. Only
1 process operation per 1 section. 14

15. Strength of HAZOP
• HAZOP is a systematic, reasonably comprehensive and flexible.
• It is suitable mainly for team use whereby it is possible to
incorporate the general experience available.
• It gives good identification of cause and excellent identification
of critical deviations.
• The use of keywords is effective and the whole group is able to
participate.
• HAZOP is an excellent well-proven method for studying large
plant in a specific manner.
• HAZOP identifies virtually all significant deviations on the
plant, all major accidents should be identified but not
necessarily their causes.
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16. HAZOP STUDY REPORT FORM
HAZOP Study Form
TITLE :
Sheet 1 of
LINE 1 :
DEVIATION CAUSES CONSEQUENCES EXISTING ACTIONS,
PROVISIONS QUESTIONS OR
RECOMMENDATIONS

17. Start Finish
YES
Select a component NO All components analysed?
YES
NO
Select a flow All flows analysed?
YES
Suggest a deviation NO
All guide words considered?
using a guide word
Record as non-hazardous Record as hazard. Make
Investigate and
deviation, with a recommendations for
document causes
justification action if necessary
Investigate and
Does deviation have plausible
document effects
NO causes and hazardous effects? YES

18.  Using relevant guide works, perform HAZOP study on shell & tube
heat exchanger
Process
fluid
Cooling water
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19. Guide Word Deviation Causes Consequences Action
Less Less flow of Pipe blockage Temperature of process High Temperature
cooling water fluid remains constant Alarm
More More cooling flow Failure of cooling Temperature of process Low Temperature
water valve fluid decrease Alarm
More of More pressure on Failure of process Bursting of tube Install high pressure
tube side fluid valve alarm
Contamination Contamination of Leakage of tube and Contamination of process Proper maintainance
process fluid line cooling water goes fluid and operator alert
in
Corrosion Corrosion of tube Hardness of cooling Less cooling and crack of Proper maintainence
water tube
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20. Guide Word Deviation Causes Consequences Action
NONE No cooling water flow Failure of inlet cooling Process fluid temperature is Install
water valve to open not lowered accordingly Temperature
indicator before
and after the
process fluid line
MORE More cooling water Failure of inlet cooling Output of Process fluid Install
flow water valve to close temperature too low Temperature
indicator before
and after process
fluid line
Install TAL
LESS Less cooling water Pipe leakage Process fluid temperature too Installation of
low flow meter
REVERSE Reverse process fluid Failure of process fluid Product off set Install check
flow inlet valve valve (whether it
is crucial have to
check?)
CONTAMINATION Process fluid Contamination in cooling Outlet temperature too low Proper
contamination water maintenance and
operator alert
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