This document provides an overview of Hazard and Operability Studies (HAZOP). It discusses the importance and methodology of HAZOP analysis, including forming a team, identifying system elements and parameters, considering deviations, and identifying hazards. Keywords such as "no", "less", and "more" are used to systematically analyze each part of a process. The document also briefly discusses applications of HAZOP for design, operational, and procedural assessments and compares it to other risk analysis tools. An example HAZOP study for an acetylene production industry is referenced.

1. Hazard and Operational Studies - HAZOP
Industrial Safety and Management
Instructor
Mr. Fakhri H. Ibrahim
Prepared by:
Safeen Yaseen Ja’far
Submitted on
25/2/2023
Koya University
Faculty of Engineering
Department of Chemical Engineering
Fourth Stage/2022-2023

2. Table of Content
Abstract ......................................................................................................................................................1
1. Introduction...........................................................................................................................................2
1.1. Introduction to HAZOP Studies.................................................................................................2
1.2. Brief history of HAZOP................................................................................................................3
2. Literature Review.................................................................................................................................4
2.1. Basic Concept & Definition of the HAZOP..............................................................................4
2.2. The Importance of HAZOP Analysis.........................................................................................4
2.3 HAZOP Study Methodology ........................................................................................................5
2.4 HAZOP Keywords..........................................................................................................................7
2.4.1 Primary Keywords..................................................................................................................7
2.4.2 Secondary Keywords ............................................................................................................8
2.5 The HAZOP Study Process..........................................................................................................9
2.5.1 Form a HAZOP Team .............................................................................................................9
2.5.2 Identify Each Element and its Parameters .....................................................................10
2.5.3 Consider the Effects of Variation......................................................................................10
2.5.4 Identify Hazards and Failure Points.................................................................................10
2.6 Applications of HAZOP...............................................................................................................11
2.7 Fault Tree Analysis (FTA)...........................................................................................................12
2.7.1 Overview & Definition .........................................................................................................12
2.7.2 Purpose of Fault Tree Analysis .........................................................................................12
2.7.3 FTA Development Steps.....................................................................................................12
2.8 HAZOP Study (Example) – Acetylene Production Industry...............................................13
3. Conclusion...........................................................................................................................................14
4. References...........................................................................................................................................14

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Abstract
In this report we will discuss about important topic which is related to our workplace
especially in industrial factories. So, as we know workplace hazards are potential sources
of harm or adverse health effects on workers. Businesses need all the means possible to
avoid accidents that could lead to injuries, fatalities, or costly property damage. One tool
that can identify hazards and evaluate risks is a Hazard and Operability study, commonly
shortened to HAZOP.

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1. Introduction
1.1. Introduction to HAZOP Studies
The technique of Hazard and Operability Studies, or in more common terms HAZOPS,
has been used and developed over approximately four decades for 'identifying potential
hazards and operability problems' caused by 'deviations from the design intent' in both
new and existing process plants. Before progressing further, it might be as well to clarify
some aspects of these statements (Mike Lihou, 2022).
Workplace safety should always be at the forefront of your mind. Many recommendations
exist on how to go about analyzing your workplace to ensure optimal performance and
safety, but the go-to recommendation is usually to complete a HAZOP analysis. A Hazard
and Operability study (HAZOP) is sometimes referred to as a Process Hazard Analysis
(PHA). The purpose of a HAZOP is to identify risks and hazards associated with the
operation of a facility. These identified risks are then managed through a business
Management of Change (MOC) process. The management of risks can vary in solution
from engineering changes, to changes in business and operational processes that would
reduce the risk to As Low As Reasonably Practicable (ALARP) (GRAPHIC PRODUCTS
STAFF, 2023).
Figure 1: Workplace safety should always be at the forefront of your mind

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1.2. Brief history of HAZOP
HAZOP became the industry standard acronym or abbreviation for Hazard and Operability
studies following pioneering work at ICI by Trevor Kletz and Ellis Knowlton in the late
1960s and early 1970s. Since then, Kletz (2006) has kept the methods up to date and
fresh via new material and mnemonic illustrations. The procedure quickly evolved
to use a fairly standard set of keyword combinations to trigger a structured team analysis
of new process designs and proposed revamps. Recently Crawley et al. 2008 have
advocated using ‘guidewords’ (more, less etc) together with ‘parameters’ (temperature,
pressure etc) rather than the less precise ‘keyword’. Whilst this clarification is welcomed,
in the present paper, both terms are used interchangeably – hopefully without
compromising the objective. In the 1980s with the advent of PCs computer software was
developed to record and review the excursions, consequences and assign actions to
responsible parties to resolve. These days the draft report is typically prepared ‘on the
spot’ by the secretary/leader using a laptop PC and projected on a screen in the meeting
room, so the team members have an opportunity (and a duty) to approve what is being
recorded. The HAZOP report became a document with potential legal significance with
the increased focus on HSE following a number of well publicized accidents in the
industry. In the 1990s the likelihood-severity matrix commonly became used for
prioritizing issues unearthed during the study. Safety Integrity Level – SIL reviews were
adopted increasingly since the late 1990s and early 2000s. This technique needs more
expertise on the part of the leader to achieve a successful review. Process Simulation
software is now available to help evaluate upset scenarios during the HAZOP study to
enable more rapid resolution of issues (Limb, D., 2009).
Figure 2: The team responsible for
defining the HAZOP process and
telling the world about it.

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2. Literature Review
2.1. Basic Concept & Definition of the HAZOP
Essentially the HAZOPS procedure involves taking a full description of a process and
systematically questioning every part of it to establish how deviations from the design
intent can arise. Once identified, an assessment is made as to whether such deviations
and their consequences can have a negative effect upon the safe and efficient operation
of the plant. If considered necessary, action is then taken to remedy the situation (Mike
Lihou, 2022).
2.2. The Importance of HAZOP Analysis
The task of analyzing hazards in a workplace or system can be daunting. However, without
an effective analysis, potential hazards may not be discovered before they result in injuries
and loss. The cost of an accident is often many times greater than the cost of the analysis
that could have stopped it. It’s the old proverb: “An ounce of prevention is worth a pound
of cure.” There are many ways to assess a process or workplace for hazards, and each
approach has strengths and weaknesses. For example, the worker-focused Job Hazard
Analysis (JHA) is particularly effective for protecting workers, because it considers each
task that a worker must perform and the safety signs that may be beneficial to prevent
risk. However, if you need to assess a long and complex system, rather than individual
workers’ safety needs, a broader hazard analysis method may be needed. OSHA lists
several common methods of finding the potential hazards in these systems, including:
• What-If Analysis
• Hazard and Operability Studies (HAZOP)
• Failure Mode and Effects Analysis (FMEA)
• Fault Tree Analysis
HAZOP is a common hazard analysis method for complex systems. It can be used to
identify problems even during the early stages of project development, as well as
identifying potential hazards in existing systems (GRAPHIC PRODUCTS STAFF, 2023).

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2.3 HAZOP Study Methodology
In simple terms, the HAZOP study process involves applying in a systematic way all
relevant keyword combinations to the plant in question in an effort to uncover potential
problems. The results are recorded in columnar format under the following headings:
Deviation Cause Consequence Safeguards Action
In considering the information to be recorded in each of these columns, it may be
helpful to take as an example the simple schematic below. Note that this is purely
representational, and not intended to illustrate an actual system.
Figure 3: The system that we can use to understand HAZOP Study
DEVIATION
The keyword combination being applied (e.g. Flow/No).
CAUSE
Potential causes that would result in the deviation occurring. For example, "Strainer S1
blockage due to impurities in Dosing Tank T1" might be a cause of Flow/No.
CONSEQUENCE
The consequences that would arise, both from the effect of the deviation such as "Loss of
dosing results in incomplete separation in V1" and if appropriate, from the cause itself, for
example "Cavitation in Pump P1, with possible damage if prolonged". Always be explicit
in recording the consequences. Do not assume that the reader at some later date will be

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fully aware of the significance of a statement such as "No dosing chemical to Mixer". It is
much better to add the explanation as set out above.
SAFEGUARDS
Any existing protective devices that either prevent the cause or safeguard against the
adverse consequences would be recorded in this column. For example, you may
consider recording "Local pressure gauge in discharge from pump might indicate
problem was arising". Note that safeguards need not be restricted to hardware… where
appropriate, credit can be taken for procedural aspects such as regular plant inspections
(if you are sure that they will actually be carried out!).
ACTION
Where a credible cause results in a negative consequence, it must be decided whether
some action should be taken. It is at this stage that consequences and associated
safeguards are considered. If it is deemed that the protective measures are adequate,
then no action need be taken, and words to that effect are recorded in the Action column
(Mike Lihou, 2022).
Actions fall into two groups:
▪ Actions that remove the cause.
▪ Actions that mitigate or eliminate the consequences.

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2.4 HAZOP Keywords
An essential feature in this process of questioning and systematic analysis is the use of
keywords to focus the attention of the team upon deviations and their possible
causes. These keywords are divided into two sub-sets:
• Primary Keywords that focus attention upon a particular aspect of the design intent
or an associated process condition or parameter.
• Secondary Keywords that, when combined with a primary keyword, suggest
possible deviations.
2.4.1 Primary Keywords
These reflect both the process design intent and operational aspects of the plant being
studied. Typical process-oriented words might be as follows. The list below is purely
illustrative, as the words employed in a review will depend upon the plant being studied.
Flow Temperature
Pressure Level
Composition Separate (settle, filter, centrifuge)
React Mix
Reduce (grind, crush, etc.) Absorb
Corrode Erode
Note that some words may be included that appear at first glance to be completely
unrelated to any reasonable interpretation of the design intent of a process. For example,
one may question the use of the word Corrode, on the assumption that no one would
intend that corrosion should occur. Bear in mind, however, that most plant is designed
with a certain life span in mind, and implicit in the design intent is that corrosion should
not occur, or if it is expected, it should not exceed a certain rate (Mike Lihou, 2022).

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2.4.2 Secondary Keywords
As mentioned above, when applied in conjunction with a Primary Keyword, these suggest
potential deviations or problems. They tend to be a standard set as listed below:
Word Meaning
No The design intent does not occur (e.g. Flow/No), or the operational
aspect is not achievable (Isolate/No)
Less A quantitative decrease in the design intent occurs (e.g. Pressure/Less)
More A quantitative increase in the design intent occurs (e.g.
Temperature/More)
Reverse The opposite of the design intent occurs (e.g. Flow/Reverse)
Also The design intent is completely fulfilled, but in addition some other
related activity occurs (e.g. Flow/Also indicating contamination in a
product stream, or Level/Also meaning material in a tank or vessel that
should not be there)
Other The activity occurs, but not in the way intended (e.g. Flow/Other could
indicate a leak or product flowing where it should not, or
Composition/Other might suggest unexpected proportions in a
feedstock)
Fluctuation The design intention is achieved only part of the time (e.g. an air-lock in a
pipeline might result in Flow/Fluctuation)
Early Usually used when studying sequential operations, this would indicate
that a step is started at the wrong time or done out of sequence
Late As for Early
It should be noted that not all combinations of Primary/Secondary words are
appropriate. For example, Temperature/No (absolute zero or -273°C !) or Reverse could
be considered as meaningless (Mike Lihou, 2022).

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2.5 The HAZOP Study Process
A Hazard and Operability Study systematically investigates each element in a process.
The goal is to find potential situations that would cause that element to pose a hazard or
limit the operability of the process as a whole. There are four basic steps to the process:
1. Forming a HAZOP team.
2. Identifying the elements of the
system.
3. Considering possible variations in
operating parameters.
4. Identifying any hazards or failure
points.
Once the four steps have been
completed, the resulting information can
lead to improvements in the system,
such as adding caution signs or traffic
signs. The best way to apply the results
of a HAZOP study will depend on the
nature of the system (GRAPHIC PRODUCTS STAFF, 2023)..
2.5.1 Form a HAZOP Team
To perform a HAZOP, a team of workers is formed, including people with a variety of
expertise such as operations, maintenance, instrumentation, engineering/process design,
and other specialists as needed. These should not be “newbies,” but people with
experience, knowledge, and an understanding of their part of the system. The key
requirements are an understanding of the system, and a willingness to consider all
reasonable variations at each point in the system.

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2.5.2 Identify Each Element and its Parameters
The HAZOP team will then create a plan for the complete work process, identifying the
individual steps or elements. This typically involves using the piping and instrument
diagrams (P&ID), or a plant model, as a guide for examining every section and component
of a process. For each element, the team will identify the planned operating parameters
of the system at that point: flow rate, pressure, temperature, vibration, and so on.
2.5.3 Consider the Effects of Variation
For each parameter, the team considers the effects of deviation from normal. For example,
“What would happen if the pressure at this valve was too high? What if the pressure was
unexpectedly low? Would the rate of change in pressure (delta-p) pose its own problems
here?” Don’t forget to consider the ways that each element interacts with others over
time; for example, “What would happen if the valve was opened too early, or too late?”
2.5.4 Identify Hazards and Failure Points
Where the result of a variation would be a danger to workers or to the production process,
you’ve found a potential problem. Document this concern, and estimate the impact of a
failure at that point. Then, determine the likelihood of that failure; is there a real cause for
the harmful variation? Evaluate the existing safeguards and protection systems, and
evaluate their ability to handle the deviations that you’ve considered (GRAPHIC
PRODUCTS STAFF, 2023).

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2.6 Applications of HAZOP
HAZOP is best suited for assessing hazards in facilities, equipment, and processes
and is capable of assessing systems from multiple perspectives:
A) Design
• Assessing system design capability to meet user specifications and safety
standards.
• Identifying weaknesses in systems
B) Physical and operational environments
• Assessing environment to ensure system is appropriately situated, supported,
serviced, contained, etc.
C) Operational and procedural controls
• Assessing engineered controls (ex: automation), sequences of operations,
procedural controls (ex: human interactions) etc.
• Assessing different operational modes – start-up, standby, normal operation,
steady & unsteady states, normal shutdown, emergency shutdown, etc.
Advantages Disadvantages
1. Helpful when confronting
hazards that are difficult to
quantify
• Hazards rooted in human
performance and
behaviors.
• Hazards that are difficult
to detect, analyze, isolate,
count, predict, etc.
2. Built-in brainstorming
methodology.
3. Systematic & comprehensive
methodology.
4. simpler and more intuitive
than other
commonly used risk
management tools
1. No means to assess hazards involving
interactions between different parts of a system or
process
2. No risk ranking or prioritization
capability.
• Teams may optionally build-in such
capability as required.
3. No means to assess effectiveness of
existing or proposed controls (safeguards)
• May need to interface HAZOP with other risk
management tools (ex:
HACCP) for this purpose

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2.7 Fault Tree Analysis (FTA)
2.7.1 Overview & Definition
A Fault Tree Analysis (FTA) is a Risk Management tool that assesses the safety-critical
functions within a system’s architecture and design. It analyzes high-level failures and
identifies all lower-level (sub-system) failures that cause them. FTA is useful during the
initial product design phase as a tool for driving the design through an evaluation of both
reliability and fault probability perspectives. It can be used to estimate and develop a
system’s performance reliability requirements to reduce the likelihood of undesired
events occurring. FTA is particularly useful in functional paths of high complexity in which
the outcome of one or more combinations of noncritical events may produce an
undesirable critical event. Typical candidates for fault tree analysis are functional paths or
interfaces which could have a critical impact on flight safety, munitions handling safety,
the safety of operating and maintenance personnel, and the probability of error-free
command in automated systems in which a multiplicity of redundant and overlapping
outputs may be involved ().
2.7.2 Purpose of Fault Tree Analysis
The purpose of a fault tree analysis is to provide a concise and orderly description of the
various combinations of possible occurrences within the system which can result in a
predetermined critical output event and mitigate them.
2.7.3 FTA Development Steps
FTA analysis involves five steps:
• Step 1: Define the undesired event to study
• Step 2: Obtain an understanding of the system
• Step 3: Construct the fault tree
• Step 4: Evaluate the fault tree
• Step 5: Control the hazards identified

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2.8 HAZOP Study (Example) – Acetylene Production Industry
Figure 4: Industrial Process of Acetylene
Table 1: Line 1 Risk Management
Guide
Word
Deviation Possible Causes Consequence Proposed
Measures
Hazards
No,
Not
No water
flow
valve failure (close),
fracture in pipeline,
water pump stops
No water flow to cool the
highly exothermic reaction
Acetylene gas
temperature
increase
Explosion and
fire
More
More
water flow
Valve wide open, high
fuel pump capacity
More water to the reactor
leads to more than tank
capacity and overflow
Water level in
reactor
Over flow of
water
Table 1: Line 1 Risk Management
Guide
Word
Deviation Possible Causes Consequence Proposed
Measures
Hazards
No,
Not
No CaC2
transfer
Fault in Jaw
crusher, fault in
screw conveyor
No CaC2 pass to the
reactor and the reaction
stop
Reaction
temperature go
down, no acetylene
out
Shutdown of the
process
More
More CaC2
transfer
High crusher
capacity, higher
screw conveyor
capacity
More solid material CaC2
pass to the reactor,
higher reaction rate,
higher temperature,
more Acetylene gas
produced
Temperature of
reactor, flowrate of
Acetylene gas out
Explosion
occurs

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3. Conclusion
This report can be summarized in these following benefits of the HAZOP as following:
✓ HAZOP is best suited for assessing hazards in facilities, equipment, and processes
and is capable of assessing systems from multiple prospectives
✓ Assessing system design capability to meet user specifications and safety standards.
✓ Identifying weaknesses in systems
✓ Assessing environment to ensure system is appropriately situated, supported,
serviced, contained, etc.
✓ Assessing different operational modes - start-up, standby, normal operation, steady
& unsteady states, normal shutdown, emergency shutdown, etc.
4. References
1. Mike Lihou, 2022. HAZOP Manager Software Development History. [online] Available
at: https://www.lihoutech.com/hazop1.htm. [Accessed 25 Feb 2023].
2. Graphic Products 2019. What Is HAZOP? [online] Graphic Products. Available at:
https://www.graphicproducts.com/articles/what-is-hazop/. [Accessed 25 Feb 2023].
3. AcqNotes., 2021. Fault Tree Analysis. [online] Available at:
https://acqnotes.com/acqnote/tasks/fault-tree-analysisrisk. [Accessed 25 Feb 2023].