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Hazard and Operability (HAZOP)
Study
Hazard and Operability (HAZOP) Ahmed Eltayef
1
HAZOP
Fundamental
Hazard and Operability (HAZOP)
Ahmed Eltayef
2
A scenario…
• You and your family 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.
Hazard and Operability (HAZOP)
Ahmed Eltayef
3
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?
(5 minutes for brainstorming ideas)
Hazard and Operability (HAZOP)
Ahmed Eltayef
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What other possible accidents might
happen on the road trip?
Can we be prepared before the accident
occurs?
Hazard and Operability (HAZOP)
Ahmed Eltayef
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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
Hazard and Operability (HAZOP)
Ahmed Eltayef
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• Systematic technique to IDENTIFY potential HAZard and
OPerating problems
• A formal systematic rigorous examination to the process and
engineering facets of a production facility
• A qualitative technique based on “guide-words” to help provoke
thoughts about the way deviations from the intended operating
conditions can lead to hazardous situations or operability problems
• HAZOP is basically for safety
- Hazards are the main concern
- Operability problems degrade plant performance (product quality,
production rate, profit)
• Considerable engineering insight is required - engineers working
independently could develop different results
What is HAZOP?
Hazard and Operability (HAZOP)
Ahmed Eltayef
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Origin of HAZOP
• Initially prepared by Dr H G Lawley and
associates of ICI at Wilton in 1960’s.
• Subsequently C J Bullock and A J D Jenning
from ChE Dept. Teeside Polytechnic under
supervision of T.A. Kletz applied the method
at higher institution (post-graduate level).
• In 1977, Chemical Industries Association
published the edited version.
Hazard and Operability (HAZOP)
Ahmed Eltayef
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Later Development - HAZOP
• ICI expanded the procedure called HAZARD
STUDY steps 1 to 6.
• The ICI six steps :
 Project exploration / preliminary project assessment – to
identify inherent hazards of process chemicals, site
suitability and probable environmental impact.
 Project definition – to identify and reduce significant
hazards associated with items and areas, check
conformity with relevant standards and codes of
practices.
USE CHECK LISTS
Hazard and Operability (HAZOP)
Ahmed Eltayef
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 Design and procurement – to examine the PID in detail for
identification of deviations from design intent capable of
causing operability problems or hazards.
 During final stages of construction – to check that all
recommended and accepted actions recorded in steps i,
ii and iii implemented.
 During plant commissioning – to check that all relevant
statutory requirements have been acknowledges and all
installed safety systems are reliably operable.
Later Development - HAZOP
Hazard and Operability (HAZOP)
Ahmed Eltayef
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 During normal operation, some time after start-
up – especially if any modification been made.
To check if changes in operation has not
invalidated the HAZOP report of step iii by
introducing new hazards.
This procedures are adopted fully or partly by
many companies around the world.
Later Development - HAZOP
Hazard and Operability (HAZOP)
Ahmed Eltayef
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Objective of HAZOP
• 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.
Hazard and Operability (HAZOP)
Ahmed Eltayef
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• HAZOP identifies potential hazards , failures and operability
problems.
• Its use is recommended as a principal method by professional
institutions and legislators on the basis of proven capabilities for
over 40 years.
• It is most effective as a team effort consists of plant and prices
designers, operating personnel, control and instrumentation
engineer etc.
• It encourages creativity in design concept evaluation.
• Its use results in fewer commissioning and operational problems
and better informed personnel, thus confirming overall cost
effectiveness improvement.
How and Why HAZOP is Used
Hazard and Operability (HAZOP)
Ahmed Eltayef
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• Necessary changes to a system for eliminating or reducing the
probability of operating deviations are suggested by the analytical
procedure.
• HAZOP provides a necessary management tool and bonus in so far
that it demonstrates to insurers and inspectors evidence of
comprehensive thoroughness.
• HAZOP reports are an integral part of plant and safety records
and are also applicable to design changes and plant modifications,
thereby containing accountability for equipment and its associated
human interface throughout the operating lifetime.
How and Why HAZOP is Used
Hazard and Operability (HAZOP)
Ahmed Eltayef
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• HAZOP technique is now used by most major companies handling
and processing hazardous material, especially those where
engineering practice involves elevated operating parameters :
- oil and gas production
- flammable and toxic chemicals
- pharmaceuticals etc
• Progressive legislation in encouraging smaller and specialty
manufacturing sites to adopt the method also as standard
practice.
How and Why HAZOP is Used
Hazard and Operability (HAZOP)
Ahmed Eltayef
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• It emphasizes upon the operating integrity of a system, thereby
leading methodically to most potential and detectable deviations
which could conceivably arise in the course of normal operating
routine
- including "start-up " and "shut-down" procedures
- as well as steady-state operations.
• It is important to remember at all times that HAZOP is an
identifying technique and not intended as a means of solving
problems nor is the method intended to be used solely as an
undisciplined means of searching for hazardous scenarios.
Purpose of HAZOP
Hazard and Operability (HAZOP)
Ahmed Eltayef
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HAZOP - Hazard and operability
HAZOP keeps all team
members focused on the
same topic and enables
them to work as a team
1 + 1 = 3
NODE: Concentrate on one location in the process
PARAMETER: Consider each process variable individually
(F, T, L, P, composition, operator action, corrosion, etc.)
GUIDE WORD: Pose a series of standard questions about deviations
from normal conditions. We assume that we know a safe “normal”
operation. Hazard and Operability (HAZOP)
Ahmed Eltayef
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HAZOP - Hazard and operability
NODE: Pipe after pump and splitter
PARAMETER*: Flow rate
GUIDE WORD*: Less (less than normal value)
• DEVIATION: less flow than normal
• CAUSE: of deviation, can be more than one
• CONSEQUENCE: of the deviation/cause
• ACTION: initial idea for correction/
prevention/mitigation
A group
members focus
on the same
issue
simultaneously
Hazard and Operability (HAZOP)
Ahmed Eltayef
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Question : How can one be certain to identify all possible deviations ?
Answer : No absolute certainty as the study is subjective and 100 %
achievement in this context can have no significance. Any individual or
corporate effort will yield results directly proportional to the
appropriate background experience of those taking part.
However, with the appropriate levels of individual project-related
expertise , such a procedure is fully capable of identifying at least 80
% of potential deviations which could rise during normal operation.
Relevant Question About HAZOP
Hazard and Operability (HAZOP)
Ahmed Eltayef
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Separate consideration is demanded for other operating modes,
such as commissioning, emergency shut-down procedures and
isolation of equipment for maintenance or modification.
Once an installation is endorsed by a properly-conducted HAZOP
study, it is these non-steady state circumstances which benefit
particularly from the technique throughout the life time of the
installation.
' Operability' must also consider the human factors involved as well
as the prediction of equipment behavior.
Relevant Question About HAZOP
Hazard and Operability (HAZOP)
Ahmed Eltayef
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Apart from the uniformity of day-to-day activities , hazards which
could cause major production interruptions and loss, possibly
leading to costly incidents, need to be identified :
• Are there chemicals used in the plant which have not been
classified as hazard because they are handled in small quantities,
are assumed harmless, or are not considered to have long-term
toxic effect upon employees?
• What hazardous materials are transported to or from the site ?
• What routes are taken ?
• What would be the consequences of accidental release?
Relevant Question About HAZOP
Hazard and Operability (HAZOP)
Ahmed Eltayef
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• What effluents are generated by the operation being carried out or
contemplated ? What regulations require to be honored for their
disposal?
• Are chemicals properly packaged & labeled?
• Are the consequences of product misuse made absolutely clear?
• Have all potential God-made events and man-made incidents (e. g
breaches of security, sabotage, electric power failure ) been
considered?
• Are the codes and standards applicable to each facility and relating
to its design , sitting and construction complied with? For example, in
pressure vessel design.
Relevant Question About HAZOP
Hazard and Operability (HAZOP)
Ahmed Eltayef
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Features of HAZOP Study
Subsystems of interest line and valve, etc
Equipment, Vessels
Modes of operation Normal operation
Start -up mode
Shutdown mode
Maintenance /construction /
inspection mode
Trigger events Human failure
Equipment /instrument/component
failure
Supply failure
Emergency environment event
Other causes of abnormal operation,
including instrument disturbance
Hazard and Operability (HAZOP)
Ahmed Eltayef
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Effects within plant Changes in chemical conditions
Changes in inventory
Change in chemical physical conditions
Hazardous conditions Release of material
Changes in material hazard characteristics
Operating limit reached
Energy source exposed etc.
Corrective actions Change of process design
Change of operating limits
Change of system reliability
Improvement of material containment
Change control system
Add/remove materials
Features of HAZOP Study
Hazard and Operability (HAZOP)
Ahmed Eltayef
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How would hazardous During normal operation
conditions detected ? Upon human failure
Upon component failure
In other circumstances
Contingency actions Improve isolation
Improve protection
Features of HAZOP Study
Hazard and Operability (HAZOP)
Ahmed Eltayef
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Documents Needed for HAZOP
Study
• For Preliminary HAZOP
– Process Flow Sheet ( PFS or PFD )
– Description of the Process
• For Detailed HAZOP
– Piping and Instrumentation Diagram ( P & ID )
– Process Calculations
– Process Data Sheets
– Instrument Data Sheets
– Interlock Schedules
– Layout Requirements
– Hazardous Area Classification
– Description of the Process
Hazard and Operability (HAZOP)
Ahmed Eltayef
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Before Detailed HAZOP
• The development of the detailed P&I Diagram is the
last stage of the process design.
• The development will follow a normal standard
procedure and include the following considerations
:
– Basic process control system - this is a closed loop control
to maintain process within an acceptable operating region.
– Alarm system - this is to bring unusual situation to
attention of a person monitoring the process in the plant
– Safety interlock system - this is to stop operation or part of
the process during emergencies.
– Relief system - this is to divert material safely during
emergencies.
Hazard and Operability (HAZOP)
Ahmed Eltayef
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P&ID
• 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,
reducers, valves, equipment, instrumentation and control interlocks.
• P&ID is normally developed from process flow diagram (PFD).
• The P&ID are used to operate the process system.
• A process cannot be adequately designed without proper P&ID.
Hazard and Operability (HAZOP)
Ahmed Eltayef
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A P&ID should include: (Basically every mechanical aspect of the plant with some exceptions)
• Instrumentation and designations
• Mechanical equipment with names and numbers
• All valves and their identifications
• Process piping, sizes and identification
• Miscellaneous - vents, drains, special fittings, sampling lines, reducers, increasers and
swagers
• Permanent start-up and flush lines
• Flow directions
• Interconnections references
• Control inputs and outputs, interlocks
• Interfaces for class changes
• Seismic category
• Quality level
• Annunciation inputs
• Computer control system input
• Vendor and contractor interfaces
• Identification of components and subsystems delivered by others
• Intended physical sequence of the equipment
P&I D
Hazard and Operability (HAZOP)
Ahmed Eltayef
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A P&ID should not include:
• Instrument root valves
• control relays
• manual switches
• equipment rating or capacity
• primary instrument tubing and valves
• pressure temperature and flow data
• elbow, tees and similar standard fittings
• extensive explanatory notes
P&I D
Hazard and Operability (HAZOP)
Ahmed Eltayef
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P&ID and Safety
• P&I Diagram
– ISA Standard
– DIN Standard
• Layers of protection
Hazard and Operability (HAZOP)
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• Procedure in HAZOP study consist of examining the process
and instrumentation (P&I) line diagram , process line by process
line .
• A list of guide words is used to generate deviations from
normal operation corresponding to all conceivable possibilities.
• Guide words covering every parameter relevant to the system
under review :i.e. flow rate and quality, pressure, temperature,
viscosity, components etc.
• Flowchart for application of HAZOP is shown in figure.
HAZOP Study Procedure
Hazard and Operability (HAZOP)
Ahmed Eltayef
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Select Line
Select deviation
e. g more flow
Is more flow possible
Move on to next
deviation
Is it hazardous or does it
prevent efficient operation ?
Will the operator know that
there is more flow ?
What changes in plant or method
will prevent the deviation or make
it less likely or protect against the
consequences ?
Is the cost of the change justified
?
Agree change (s)
Agree who is responsible for
action
Consider other
causes of
more flow
What change in plant
will tell him ?
Consider other
change(s) or
agreed to accept
hazard
Follow up to see action has been
taken
HAZOP Study Flow Chart
Hazard and Operability (HAZOP)
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Guidelines for Division into Sections
• 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. E.g piping which contains
control valves can give rise to flow deviations, heat
exchangers can cause T deviations.
– Materials in section – contain significant amount of
hazardous materials.
– Section based on process and states of materials. Only 1
process operation per 1 section.
Hazard and Operability (HAZOP)
Ahmed Eltayef
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• General guidelines :
– Define each major process component as a section.
Usually anything assigned equipment number should be
considered a major process component.
– Define one line section between each major process
component.
– Define additional line sections for each branches off the
main process flow.
– Define a process section at each connection to existing
equipment.
Guidelines for Division into Sections
Hazard and Operability (HAZOP)
Ahmed Eltayef
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• Supplementary guidelines
– Define only one process section for equipment in identical
service. However, pumps in different service with a
common spare must be treated separately.
– Define only one line at the end of a series of components if
there are no other flow paths.
– Define only one additional line section if there are
alternative flow paths, regardless of how many branches
there are.
Guidelines for Division into Sections
Hazard and Operability (HAZOP)
Ahmed Eltayef
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• Do not define line between major equipment items
if there are no single active components that
could cause deviations.
• Do not define sections for existing equipment that
is upstream of new or modified equipment.
Address malfunctions of such upstream
equipment as deviations in the new or modified
equipment.
Guidelines for Division into Sections
Hazard and Operability (HAZOP)
Ahmed Eltayef
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GUIDE WORDS *
POSSIBLE CAUSES DEVIATION ( FROM DESIGN AND/OR
OPERATING INTENT )
CONSEQUENCES
ACTION(S) REQUIRED OR RECOMMENDEED
HAZOP Study Procedure
Hazard and Operability (HAZOP)
Ahmed Eltayef
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NONE No forward flow when there should be
MORE More of any parameter than there should be,
e.g more flow, more pressure, more
temperature, etc.
LESS As above, but "less of" in each instance
PART System composition difference from what it
should be
MORE THAN More "components" present than there should
be for example, extra phase, impurities
OTHER What needs to happen other than normal
operation, e.g. start up,shutdown, maintenance
Guide Words
Hazard and Operability (HAZOP)
Ahmed Eltayef
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NONE e.g., NO FLOW caused by blockage; pump failure;
valve closed or jammed : leak: valve open ;suction
vessel empty; delivery side over - pressurized :
vapor lock ; control failure
REVERSE e.g., REVERSE FLOW caused by pump failure : NRV
failure or wrongly inserted ; wrong routing; delivery
over pressured; back- siphoning ; pump reversed
MORE OF e.g., MORE FLOW caused by reduced delivery head
; surging ; suction pressurised ; controller failure ;
valve stuck open leak ; incorrect instrument reading.
Guide Words
Hazard and Operability (HAZOP)
Ahmed Eltayef
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MORE 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.
LESS OF e.g., LESS FLOW caused by pump failure; leak; scale in
delivery; partial blockage ; sediments ; poor suction
head; process turndown.
LESS e.g., low temperature, pressure caused by Heat loss;
vaporisation ; ambient conditions; rain ; imbalance of
input and output ; sealing ; blocked vent .
PART OF Change in composition high or low concentration of
mixture; additional reactions in reactor or other
location ; feed change.
Guide Words
Hazard and Operability (HAZOP)
Ahmed Eltayef
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MORE THAN 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.
OTHER 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.
Guide Words
Hazard and Operability (HAZOP)
Ahmed Eltayef
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HAZOP STUDY REPORT FORM
TITLE :
Sheet 1 of
LINE 1 :
DEVIATION
CAUSES CONSEQUENCES EXISTING PROVISIONS ACTIONS, QUESTIONS OR
RECOMMENDATIONS
HAZOP Study Form
Hazard and Operability (HAZOP)
Ahmed Eltayef
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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.
HAZOP Study
Hazard and Operability (HAZOP)
Ahmed Eltayef
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• 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.
Strength of HAZOP
Hazard and Operability (HAZOP)
Ahmed Eltayef
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• HAZOP is very time consuming and can be laborious with a
tendency for boredom for analysts.
• It tends to be hardware-oriented and process-oriented, although
the technique should be amenable to human error application.
• It tends to generate many failure events with insignificance
consequences and generate many failure events which have the
same consequences.
• It stifles brainstorming although this is not required at the late
stage of design when it is normally applied.
• HAZOP does not identify all causes of deviations and therefore
omits many scenarios.
Weakness of HAZOP
Hazard and Operability (HAZOP)
Ahmed Eltayef
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• It takes little account of the probabilities of events or
consequences, although quantitative assessment are sometime
added. The group generally let their collective experiences decide
whether deviations are meaningful.
• HAZOP is poor where multiple-combination events can have
severe effects.
• It tends to assume defects or deterioration of materials of
construction will not arise.
• When identifying consequences, HAZOP tends to encourage
listing these as resulting in action by emergency control measures
without considering that such action might fail. It tends to ignore
the contribution which can be made by operator interventions
Weakness of HAZOP
Hazard and Operability (HAZOP)
Ahmed Eltayef
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Managing HAZOP
How to manage HAZOP
Hazard and Operability (HAZOP)
Ahmed Eltayef
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Preliminary HAZOP Example
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
Hazard and Operability (HAZOP)
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Preliminary HAZOP on Reactor -
Example
Guide Word Deviation Causes Consequences Action
NO No cooling 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
Hazard and Operability (HAZOP)
Ahmed Eltayef
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Preliminary HAZOP on Reactor –
Answer
Guide Word Deviation Causes Consequences Action
NO No cooling Cooling water valve
malfunction
Temperature increase in
reactor
Install high temperature
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?
Hazard and Operability (HAZOP)
Ahmed Eltayef
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Case Study – Shell & Tube Heat
Exchanger
• Using relevant guide works, perform HAZOP study on shell & tube
heat exchanger
Process
fluid
Cooling water
Hazard and Operability (HAZOP)
Ahmed Eltayef
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HAZOP on Heat Exchanger –
Answer 1
Guide Word Deviation Causes Consequences Action
Less Less flow of
cooling water
Pipe blockage Temperature of process
fluid remains constant
High Temperature
Alarm
More More cooling flow Failure of cooling
water valve
Temperature of process
fluid decrease
Low Temperature
Alarm
More of More pressure on
tube side
Failure of process
fluid valve
Bursting of tube Install high pressure
alarm
Contamination Contamination of
process fluid line
Leakage of tube and
cooling water goes
in
Contamination of process
fluid
Proper maintainance
and operator alert
Corrosion Corrosion of tube Hardness of cooling
water
Less cooling and crack of
tube
Proper maintainence
Hazard and Operability (HAZOP)
Ahmed Eltayef
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HAZOP on Heat Exchanger –
Answer 2
Guide Word Deviation Causes Consequences Action
NONE No cooling water flow Failure of inlet cooling
water valve to open
Process fluid temperature is
not lowered accordingly
Install Temperature
indicator before and after
the process fluid line
Install TAH
MORE More cooling water
flow
Failure of inlet cooling
water valve to close
Output of Process fluid
temperature too low
Install Temperature
indicator before and after
process fluid line
Install TAL
LESS Less cooling water Pipe leakage Process fluid temperature too
low
Installation of flow meter
REVERSE Reverse process fluid
flow
Failure of process fluid inlet
valve
Product off set Install check valve (whether
it is crucial have to check?)
CONTAMINATION Process fluid
contamination
Contamination in cooling
water
Outlet temperature too low Proper maintenance and
operator alert
Hazard and Operability (HAZOP)
Ahmed Eltayef
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HAZOP - Hazard and Operability
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
Hazard and Operability (HAZOP)
Ahmed Eltayef
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I suppose that I
should have done that
HAZOP Study!
Hazard and Operability (HAZOP)
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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.
Hazard and Operability (HAZOP)
Ahmed Eltayef
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Case Study
Case study hydrogen plant
Hazard and Operability (HAZOP)
Ahmed Eltayef
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Sample Answers
result HAZOP reactor.doc
Hazard and Operability (HAZOP)
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HAZOP Management
Hazard and Operability (HAZOP)
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What is required?
• Define objectives and scope – define TOR and scope of work.
•To new design – applied to a detailed design.
•To existing design – identify hazards not previously
identified probably because not being HAZOPED.
•To plant modification
• Select team members. Two types of person needed :
•Detailed technical knowledge of the process.
•Those with knowledge and experience of applying highly
structured, systematic HAZOP approach.
Planning for HAZOP Study
Hazard and Operability (HAZOP)
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• Prepare for the study. Need sufficient information :
• Process Flow Sheet ( PFS or PFD )
• Piping and Instrumentation Diagram ( P & ID )
• Process Calculations
• Process Data Sheets
• Instrument Data Sheets
• Interlock Schedules
• Layout Requirements
• Hazardous Area Classification
• Operating instructions
Planning for HAZOP
Hazard and Operability (HAZOP)
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• Prepare for the study. Need sufficient information :
• Safety procedures documents
• Relief/venting philosophy
• Chemical involved
• Piping specifications
• Previous HAZOP report
Planning for HAZOP
Hazard and Operability (HAZOP)
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Planning for HAZOP
• Carry out the study
• Record the results (may need a secretary)
• Follow-up of actions noted
– final report contain resolution of all
recommended actions
– must appoint someone as leader to check
progress of action
– team may meet again if answers to questions do
not simply lead to an action
– team may meet again if significant design
changes in interim report
Hazard and Operability (HAZOP)
Ahmed Eltayef
64
Team Characteristics
– Members share common objectives.
– Everybody contributes and knows his/her roles, not
leader dependent too much.
– Each members values and respects contribution of
others.
– Members learn while they work.
– Over a period of time, individual contribution level are
more or less equal.
– Disagreement are worked through by discussion.
– The use of voting procedures is sparing and normally
only last resort if highly necessary.
– Members enjoy team meetings.
Hazard and Operability (HAZOP)
Ahmed Eltayef
65
Questioning Techniques
• Open questions
– Help person being asked to think – use words
how, what and why.
• Closed questions
– To focus on an issue or problem. Start with
words who, when, where.
– Required answer yes or no only.
• Question mix
– Mix between open and closed questions.
Hazard and Operability (HAZOP)
Ahmed Eltayef
66
• Things to avoid
– Ambiguous or vague questions.
– Double barelled/multiple questions.
– Long complicated questions.
– Interrogation type of questions.
– A loaded questions – implied judgement.
Questioning Techniques
Hazard and Operability (HAZOP)
Ahmed Eltayef
67
HAZOP leader
• Plan sessions and timetable
• Control discussion
• Limit discussion
• Encourage team to draw conclusion
• Ensure secretary has time for taking note
• Keep team in focus
• Encourage imagination of team members
• Motivate members
• Discourage recriminations
• Judge importance issues
Responsibility of HAZOP Team
Members
Hazard and Operability (HAZOP)
Ahmed Eltayef
68
Checklist for HAZOP Leader
• Always prepare study program in advance.
• Agree on the format or form to be used.
• Prepare follow up procedures.
• Brief members about HAZOP during first
meeting.
• Stop the team trying to redesign the
process.
• HAZOP is a team exercise. Do not let
anybody (including the leader himself to
dominate).
Hazard and Operability (HAZOP)
Ahmed Eltayef
69
Checklist for HAZOP Leader
• If conflict arises, handle with care.
• Avoid long discussions by recording areas
which need to be resolved outside meeting.
• Leader must be strong, yet diplomatic.
• Speak clearly. Make you point.
• Better have experience working as team
member previously.
• Do not skip anything….some time small
things may cause big accident.
Hazard and Operability (HAZOP)
Ahmed Eltayef
70
HAZOP Secretary
• Take adequate notes
• Record documentations
• Inform leader if more time required in taking notes
• If unclear, check wording before writing
• Produce interim lists of recommendations
• Produce draft report of study
• Check progress of chase action
• Produce final report
Responsibility of HAZOP Team
Members
Hazard and Operability (HAZOP)
Ahmed Eltayef
71
Process Engineer
• Provide a simple description
• Provide design intention for each process unit
• Provide information on process conditions and design conditions
• Provide a simple description
• Provide design intention for each process unit
• Provide information on process conditions and design conditions
Responsibility of HAZOP Team
Members
Hazard and Operability (HAZOP)
Ahmed Eltayef
72
Mechanical Design Engineer
• Provide specification details
• Provide vendor package details
• Provide equipment and piping layout information
Instrument Engineer
• Provide details of control philosophy
• Provide interlock and alarm details
• Provide info on shutdown, safety features
Responsibility of HAZOP Team
Members
Hazard and Operability (HAZOP)
Ahmed Eltayef
73
Plant Engineer or Manager
• Provide information on compatibility with any existing adjacent
plant
• Provide details of site utilities and services
• Provide (for study on existing plant) any update on maintenance
access and modifications
Shift Operating Engineer or Supervisor
• Provide guidance on control instrumentation integrity from an
operating experience view point
• Provide (for study on existing plant) information on plant stability
at the specified control parameters
• Provide information on experienced operability deviations of
hazard potential
Responsibility of HAZOP Team
Members
Hazard and Operability (HAZOP)
Ahmed Eltayef
74
Chemist
• Provide details of process chemistry
• Provide details of process hazards (polymerisations, byproducts,
corrosion etc)
Project Engineer
• Provide details of cost and time estimation and also budget
constraints.
• Ensure rapid approval if required
Responsibility of HAZOP Team
Members
Hazard and Operability (HAZOP)
Ahmed Eltayef

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HAZOP.pdf HSE awareness program for factory working sites

  • 1. 0 Hazard and Operability (HAZOP) Study Hazard and Operability (HAZOP) Ahmed Eltayef
  • 3. 2 A scenario… • You and your family 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. Hazard and Operability (HAZOP) Ahmed Eltayef
  • 4. 3 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? (5 minutes for brainstorming ideas) Hazard and Operability (HAZOP) Ahmed Eltayef
  • 5. 4 What other possible accidents might happen on the road trip? Can we be prepared before the accident occurs? Hazard and Operability (HAZOP) Ahmed Eltayef
  • 6. 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 Hazard and Operability (HAZOP) Ahmed Eltayef
  • 7. 6 • Systematic technique to IDENTIFY potential HAZard and OPerating problems • A formal systematic rigorous examination to the process and engineering facets of a production facility • A qualitative technique based on “guide-words” to help provoke thoughts about the way deviations from the intended operating conditions can lead to hazardous situations or operability problems • HAZOP is basically for safety - Hazards are the main concern - Operability problems degrade plant performance (product quality, production rate, profit) • Considerable engineering insight is required - engineers working independently could develop different results What is HAZOP? Hazard and Operability (HAZOP) Ahmed Eltayef
  • 8. 7 Origin of HAZOP • Initially prepared by Dr H G Lawley and associates of ICI at Wilton in 1960’s. • Subsequently C J Bullock and A J D Jenning from ChE Dept. Teeside Polytechnic under supervision of T.A. Kletz applied the method at higher institution (post-graduate level). • In 1977, Chemical Industries Association published the edited version. Hazard and Operability (HAZOP) Ahmed Eltayef
  • 9. 8 Later Development - HAZOP • ICI expanded the procedure called HAZARD STUDY steps 1 to 6. • The ICI six steps :  Project exploration / preliminary project assessment – to identify inherent hazards of process chemicals, site suitability and probable environmental impact.  Project definition – to identify and reduce significant hazards associated with items and areas, check conformity with relevant standards and codes of practices. USE CHECK LISTS Hazard and Operability (HAZOP) Ahmed Eltayef
  • 10. 9  Design and procurement – to examine the PID in detail for identification of deviations from design intent capable of causing operability problems or hazards.  During final stages of construction – to check that all recommended and accepted actions recorded in steps i, ii and iii implemented.  During plant commissioning – to check that all relevant statutory requirements have been acknowledges and all installed safety systems are reliably operable. Later Development - HAZOP Hazard and Operability (HAZOP) Ahmed Eltayef
  • 11. 10  During normal operation, some time after start- up – especially if any modification been made. To check if changes in operation has not invalidated the HAZOP report of step iii by introducing new hazards. This procedures are adopted fully or partly by many companies around the world. Later Development - HAZOP Hazard and Operability (HAZOP) Ahmed Eltayef
  • 12. 11 Objective of HAZOP • 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. Hazard and Operability (HAZOP) Ahmed Eltayef
  • 13. 12 • HAZOP identifies potential hazards , failures and operability problems. • Its use is recommended as a principal method by professional institutions and legislators on the basis of proven capabilities for over 40 years. • It is most effective as a team effort consists of plant and prices designers, operating personnel, control and instrumentation engineer etc. • It encourages creativity in design concept evaluation. • Its use results in fewer commissioning and operational problems and better informed personnel, thus confirming overall cost effectiveness improvement. How and Why HAZOP is Used Hazard and Operability (HAZOP) Ahmed Eltayef
  • 14. 13 • Necessary changes to a system for eliminating or reducing the probability of operating deviations are suggested by the analytical procedure. • HAZOP provides a necessary management tool and bonus in so far that it demonstrates to insurers and inspectors evidence of comprehensive thoroughness. • HAZOP reports are an integral part of plant and safety records and are also applicable to design changes and plant modifications, thereby containing accountability for equipment and its associated human interface throughout the operating lifetime. How and Why HAZOP is Used Hazard and Operability (HAZOP) Ahmed Eltayef
  • 15. 14 • HAZOP technique is now used by most major companies handling and processing hazardous material, especially those where engineering practice involves elevated operating parameters : - oil and gas production - flammable and toxic chemicals - pharmaceuticals etc • Progressive legislation in encouraging smaller and specialty manufacturing sites to adopt the method also as standard practice. How and Why HAZOP is Used Hazard and Operability (HAZOP) Ahmed Eltayef
  • 16. 15 • It emphasizes upon the operating integrity of a system, thereby leading methodically to most potential and detectable deviations which could conceivably arise in the course of normal operating routine - including "start-up " and "shut-down" procedures - as well as steady-state operations. • It is important to remember at all times that HAZOP is an identifying technique and not intended as a means of solving problems nor is the method intended to be used solely as an undisciplined means of searching for hazardous scenarios. Purpose of HAZOP Hazard and Operability (HAZOP) Ahmed Eltayef
  • 17. 16 HAZOP - Hazard and operability HAZOP keeps all team members focused on the same topic and enables them to work as a team 1 + 1 = 3 NODE: Concentrate on one location in the process PARAMETER: Consider each process variable individually (F, T, L, P, composition, operator action, corrosion, etc.) GUIDE WORD: Pose a series of standard questions about deviations from normal conditions. We assume that we know a safe “normal” operation. Hazard and Operability (HAZOP) Ahmed Eltayef
  • 18. 17 HAZOP - Hazard and operability NODE: Pipe after pump and splitter PARAMETER*: Flow rate GUIDE WORD*: Less (less than normal value) • DEVIATION: less flow than normal • CAUSE: of deviation, can be more than one • CONSEQUENCE: of the deviation/cause • ACTION: initial idea for correction/ prevention/mitigation A group members focus on the same issue simultaneously Hazard and Operability (HAZOP) Ahmed Eltayef
  • 19. 18 Question : How can one be certain to identify all possible deviations ? Answer : No absolute certainty as the study is subjective and 100 % achievement in this context can have no significance. Any individual or corporate effort will yield results directly proportional to the appropriate background experience of those taking part. However, with the appropriate levels of individual project-related expertise , such a procedure is fully capable of identifying at least 80 % of potential deviations which could rise during normal operation. Relevant Question About HAZOP Hazard and Operability (HAZOP) Ahmed Eltayef
  • 20. 19 Separate consideration is demanded for other operating modes, such as commissioning, emergency shut-down procedures and isolation of equipment for maintenance or modification. Once an installation is endorsed by a properly-conducted HAZOP study, it is these non-steady state circumstances which benefit particularly from the technique throughout the life time of the installation. ' Operability' must also consider the human factors involved as well as the prediction of equipment behavior. Relevant Question About HAZOP Hazard and Operability (HAZOP) Ahmed Eltayef
  • 21. 20 Apart from the uniformity of day-to-day activities , hazards which could cause major production interruptions and loss, possibly leading to costly incidents, need to be identified : • Are there chemicals used in the plant which have not been classified as hazard because they are handled in small quantities, are assumed harmless, or are not considered to have long-term toxic effect upon employees? • What hazardous materials are transported to or from the site ? • What routes are taken ? • What would be the consequences of accidental release? Relevant Question About HAZOP Hazard and Operability (HAZOP) Ahmed Eltayef
  • 22. 21 • What effluents are generated by the operation being carried out or contemplated ? What regulations require to be honored for their disposal? • Are chemicals properly packaged & labeled? • Are the consequences of product misuse made absolutely clear? • Have all potential God-made events and man-made incidents (e. g breaches of security, sabotage, electric power failure ) been considered? • Are the codes and standards applicable to each facility and relating to its design , sitting and construction complied with? For example, in pressure vessel design. Relevant Question About HAZOP Hazard and Operability (HAZOP) Ahmed Eltayef
  • 23. 22 Features of HAZOP Study Subsystems of interest line and valve, etc Equipment, Vessels Modes of operation Normal operation Start -up mode Shutdown mode Maintenance /construction / inspection mode Trigger events Human failure Equipment /instrument/component failure Supply failure Emergency environment event Other causes of abnormal operation, including instrument disturbance Hazard and Operability (HAZOP) Ahmed Eltayef
  • 24. 23 Effects within plant Changes in chemical conditions Changes in inventory Change in chemical physical conditions Hazardous conditions Release of material Changes in material hazard characteristics Operating limit reached Energy source exposed etc. Corrective actions Change of process design Change of operating limits Change of system reliability Improvement of material containment Change control system Add/remove materials Features of HAZOP Study Hazard and Operability (HAZOP) Ahmed Eltayef
  • 25. 24 How would hazardous During normal operation conditions detected ? Upon human failure Upon component failure In other circumstances Contingency actions Improve isolation Improve protection Features of HAZOP Study Hazard and Operability (HAZOP) Ahmed Eltayef
  • 26. 25 Documents Needed for HAZOP Study • For Preliminary HAZOP – Process Flow Sheet ( PFS or PFD ) – Description of the Process • For Detailed HAZOP – Piping and Instrumentation Diagram ( P & ID ) – Process Calculations – Process Data Sheets – Instrument Data Sheets – Interlock Schedules – Layout Requirements – Hazardous Area Classification – Description of the Process Hazard and Operability (HAZOP) Ahmed Eltayef
  • 27. 26 Before Detailed HAZOP • The development of the detailed P&I Diagram is the last stage of the process design. • The development will follow a normal standard procedure and include the following considerations : – Basic process control system - this is a closed loop control to maintain process within an acceptable operating region. – Alarm system - this is to bring unusual situation to attention of a person monitoring the process in the plant – Safety interlock system - this is to stop operation or part of the process during emergencies. – Relief system - this is to divert material safely during emergencies. Hazard and Operability (HAZOP) Ahmed Eltayef
  • 28. 27 P&ID • 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, reducers, valves, equipment, instrumentation and control interlocks. • P&ID is normally developed from process flow diagram (PFD). • The P&ID are used to operate the process system. • A process cannot be adequately designed without proper P&ID. Hazard and Operability (HAZOP) Ahmed Eltayef
  • 29. 28 A P&ID should include: (Basically every mechanical aspect of the plant with some exceptions) • Instrumentation and designations • Mechanical equipment with names and numbers • All valves and their identifications • Process piping, sizes and identification • Miscellaneous - vents, drains, special fittings, sampling lines, reducers, increasers and swagers • Permanent start-up and flush lines • Flow directions • Interconnections references • Control inputs and outputs, interlocks • Interfaces for class changes • Seismic category • Quality level • Annunciation inputs • Computer control system input • Vendor and contractor interfaces • Identification of components and subsystems delivered by others • Intended physical sequence of the equipment P&I D Hazard and Operability (HAZOP) Ahmed Eltayef
  • 30. 29 A P&ID should not include: • Instrument root valves • control relays • manual switches • equipment rating or capacity • primary instrument tubing and valves • pressure temperature and flow data • elbow, tees and similar standard fittings • extensive explanatory notes P&I D Hazard and Operability (HAZOP) Ahmed Eltayef
  • 31. 30 P&ID and Safety • P&I Diagram – ISA Standard – DIN Standard • Layers of protection Hazard and Operability (HAZOP) Ahmed Eltayef
  • 32. 31 • Procedure in HAZOP study consist of examining the process and instrumentation (P&I) line diagram , process line by process line . • A list of guide words is used to generate deviations from normal operation corresponding to all conceivable possibilities. • Guide words covering every parameter relevant to the system under review :i.e. flow rate and quality, pressure, temperature, viscosity, components etc. • Flowchart for application of HAZOP is shown in figure. HAZOP Study Procedure Hazard and Operability (HAZOP) Ahmed Eltayef
  • 33. 32 Select Line Select deviation e. g more flow Is more flow possible Move on to next deviation Is it hazardous or does it prevent efficient operation ? Will the operator know that there is more flow ? What changes in plant or method will prevent the deviation or make it less likely or protect against the consequences ? Is the cost of the change justified ? Agree change (s) Agree who is responsible for action Consider other causes of more flow What change in plant will tell him ? Consider other change(s) or agreed to accept hazard Follow up to see action has been taken HAZOP Study Flow Chart Hazard and Operability (HAZOP) Ahmed Eltayef
  • 34. 33 Guidelines for Division into Sections • 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. E.g piping which contains control valves can give rise to flow deviations, heat exchangers can cause T deviations. – Materials in section – contain significant amount of hazardous materials. – Section based on process and states of materials. Only 1 process operation per 1 section. Hazard and Operability (HAZOP) Ahmed Eltayef
  • 35. 34 • General guidelines : – Define each major process component as a section. Usually anything assigned equipment number should be considered a major process component. – Define one line section between each major process component. – Define additional line sections for each branches off the main process flow. – Define a process section at each connection to existing equipment. Guidelines for Division into Sections Hazard and Operability (HAZOP) Ahmed Eltayef
  • 36. 35 • Supplementary guidelines – Define only one process section for equipment in identical service. However, pumps in different service with a common spare must be treated separately. – Define only one line at the end of a series of components if there are no other flow paths. – Define only one additional line section if there are alternative flow paths, regardless of how many branches there are. Guidelines for Division into Sections Hazard and Operability (HAZOP) Ahmed Eltayef
  • 37. 36 • Do not define line between major equipment items if there are no single active components that could cause deviations. • Do not define sections for existing equipment that is upstream of new or modified equipment. Address malfunctions of such upstream equipment as deviations in the new or modified equipment. Guidelines for Division into Sections Hazard and Operability (HAZOP) Ahmed Eltayef
  • 38. 37 GUIDE WORDS * POSSIBLE CAUSES DEVIATION ( FROM DESIGN AND/OR OPERATING INTENT ) CONSEQUENCES ACTION(S) REQUIRED OR RECOMMENDEED HAZOP Study Procedure Hazard and Operability (HAZOP) Ahmed Eltayef
  • 39. 38 NONE No forward flow when there should be MORE More of any parameter than there should be, e.g more flow, more pressure, more temperature, etc. LESS As above, but "less of" in each instance PART System composition difference from what it should be MORE THAN More "components" present than there should be for example, extra phase, impurities OTHER What needs to happen other than normal operation, e.g. start up,shutdown, maintenance Guide Words Hazard and Operability (HAZOP) Ahmed Eltayef
  • 40. 39 NONE e.g., NO FLOW caused by blockage; pump failure; valve closed or jammed : leak: valve open ;suction vessel empty; delivery side over - pressurized : vapor lock ; control failure REVERSE e.g., REVERSE FLOW caused by pump failure : NRV failure or wrongly inserted ; wrong routing; delivery over pressured; back- siphoning ; pump reversed MORE OF e.g., MORE FLOW caused by reduced delivery head ; surging ; suction pressurised ; controller failure ; valve stuck open leak ; incorrect instrument reading. Guide Words Hazard and Operability (HAZOP) Ahmed Eltayef
  • 41. 40 MORE 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. LESS OF e.g., LESS FLOW caused by pump failure; leak; scale in delivery; partial blockage ; sediments ; poor suction head; process turndown. LESS e.g., low temperature, pressure caused by Heat loss; vaporisation ; ambient conditions; rain ; imbalance of input and output ; sealing ; blocked vent . PART OF Change in composition high or low concentration of mixture; additional reactions in reactor or other location ; feed change. Guide Words Hazard and Operability (HAZOP) Ahmed Eltayef
  • 42. 41 MORE THAN 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. OTHER 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. Guide Words Hazard and Operability (HAZOP) Ahmed Eltayef
  • 43. 42 HAZOP STUDY REPORT FORM TITLE : Sheet 1 of LINE 1 : DEVIATION CAUSES CONSEQUENCES EXISTING PROVISIONS ACTIONS, QUESTIONS OR RECOMMENDATIONS HAZOP Study Form Hazard and Operability (HAZOP) Ahmed Eltayef
  • 44. 43 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. HAZOP Study Hazard and Operability (HAZOP) Ahmed Eltayef
  • 45. 44 • 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. Strength of HAZOP Hazard and Operability (HAZOP) Ahmed Eltayef
  • 46. 45 • HAZOP is very time consuming and can be laborious with a tendency for boredom for analysts. • It tends to be hardware-oriented and process-oriented, although the technique should be amenable to human error application. • It tends to generate many failure events with insignificance consequences and generate many failure events which have the same consequences. • It stifles brainstorming although this is not required at the late stage of design when it is normally applied. • HAZOP does not identify all causes of deviations and therefore omits many scenarios. Weakness of HAZOP Hazard and Operability (HAZOP) Ahmed Eltayef
  • 47. 46 • It takes little account of the probabilities of events or consequences, although quantitative assessment are sometime added. The group generally let their collective experiences decide whether deviations are meaningful. • HAZOP is poor where multiple-combination events can have severe effects. • It tends to assume defects or deterioration of materials of construction will not arise. • When identifying consequences, HAZOP tends to encourage listing these as resulting in action by emergency control measures without considering that such action might fail. It tends to ignore the contribution which can be made by operator interventions Weakness of HAZOP Hazard and Operability (HAZOP) Ahmed Eltayef
  • 48. 47 Managing HAZOP How to manage HAZOP Hazard and Operability (HAZOP) Ahmed Eltayef
  • 49. 48 Preliminary HAZOP Example 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 Hazard and Operability (HAZOP) Ahmed Eltayef
  • 50. 49 Preliminary HAZOP on Reactor - Example Guide Word Deviation Causes Consequences Action NO No cooling 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 Hazard and Operability (HAZOP) Ahmed Eltayef
  • 51. 50 Preliminary HAZOP on Reactor – Answer Guide Word Deviation Causes Consequences Action NO No cooling Cooling water valve malfunction Temperature increase in reactor Install high temperature 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? Hazard and Operability (HAZOP) Ahmed Eltayef
  • 52. 51 Case Study – Shell & Tube Heat Exchanger • Using relevant guide works, perform HAZOP study on shell & tube heat exchanger Process fluid Cooling water Hazard and Operability (HAZOP) Ahmed Eltayef
  • 53. 52 HAZOP on Heat Exchanger – Answer 1 Guide Word Deviation Causes Consequences Action Less Less flow of cooling water Pipe blockage Temperature of process fluid remains constant High Temperature Alarm More More cooling flow Failure of cooling water valve Temperature of process fluid decrease Low Temperature Alarm More of More pressure on tube side Failure of process fluid valve Bursting of tube Install high pressure alarm Contamination Contamination of process fluid line Leakage of tube and cooling water goes in Contamination of process fluid Proper maintainance and operator alert Corrosion Corrosion of tube Hardness of cooling water Less cooling and crack of tube Proper maintainence Hazard and Operability (HAZOP) Ahmed Eltayef
  • 54. 53 HAZOP on Heat Exchanger – Answer 2 Guide Word Deviation Causes Consequences Action NONE No cooling water flow Failure of inlet cooling water valve to open Process fluid temperature is not lowered accordingly Install Temperature indicator before and after the process fluid line Install TAH MORE More cooling water flow Failure of inlet cooling water valve to close Output of Process fluid temperature too low Install Temperature indicator before and after process fluid line Install TAL LESS Less cooling water Pipe leakage Process fluid temperature too low Installation of flow meter REVERSE Reverse process fluid flow Failure of process fluid inlet valve Product off set Install check valve (whether it is crucial have to check?) CONTAMINATION Process fluid contamination Contamination in cooling water Outlet temperature too low Proper maintenance and operator alert Hazard and Operability (HAZOP) Ahmed Eltayef
  • 55. 54 HAZOP - Hazard and Operability 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 Hazard and Operability (HAZOP) Ahmed Eltayef
  • 56. 55 I suppose that I should have done that HAZOP Study! Hazard and Operability (HAZOP) Ahmed Eltayef
  • 57. 56 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. Hazard and Operability (HAZOP) Ahmed Eltayef
  • 58. 57 Case Study Case study hydrogen plant Hazard and Operability (HAZOP) Ahmed Eltayef
  • 59. 58 Sample Answers result HAZOP reactor.doc Hazard and Operability (HAZOP) Ahmed Eltayef
  • 60. 59 HAZOP Management Hazard and Operability (HAZOP) Ahmed Eltayef
  • 61. 60 What is required? • Define objectives and scope – define TOR and scope of work. •To new design – applied to a detailed design. •To existing design – identify hazards not previously identified probably because not being HAZOPED. •To plant modification • Select team members. Two types of person needed : •Detailed technical knowledge of the process. •Those with knowledge and experience of applying highly structured, systematic HAZOP approach. Planning for HAZOP Study Hazard and Operability (HAZOP) Ahmed Eltayef
  • 62. 61 • Prepare for the study. Need sufficient information : • Process Flow Sheet ( PFS or PFD ) • Piping and Instrumentation Diagram ( P & ID ) • Process Calculations • Process Data Sheets • Instrument Data Sheets • Interlock Schedules • Layout Requirements • Hazardous Area Classification • Operating instructions Planning for HAZOP Hazard and Operability (HAZOP) Ahmed Eltayef
  • 63. 62 • Prepare for the study. Need sufficient information : • Safety procedures documents • Relief/venting philosophy • Chemical involved • Piping specifications • Previous HAZOP report Planning for HAZOP Hazard and Operability (HAZOP) Ahmed Eltayef
  • 64. 63 Planning for HAZOP • Carry out the study • Record the results (may need a secretary) • Follow-up of actions noted – final report contain resolution of all recommended actions – must appoint someone as leader to check progress of action – team may meet again if answers to questions do not simply lead to an action – team may meet again if significant design changes in interim report Hazard and Operability (HAZOP) Ahmed Eltayef
  • 65. 64 Team Characteristics – Members share common objectives. – Everybody contributes and knows his/her roles, not leader dependent too much. – Each members values and respects contribution of others. – Members learn while they work. – Over a period of time, individual contribution level are more or less equal. – Disagreement are worked through by discussion. – The use of voting procedures is sparing and normally only last resort if highly necessary. – Members enjoy team meetings. Hazard and Operability (HAZOP) Ahmed Eltayef
  • 66. 65 Questioning Techniques • Open questions – Help person being asked to think – use words how, what and why. • Closed questions – To focus on an issue or problem. Start with words who, when, where. – Required answer yes or no only. • Question mix – Mix between open and closed questions. Hazard and Operability (HAZOP) Ahmed Eltayef
  • 67. 66 • Things to avoid – Ambiguous or vague questions. – Double barelled/multiple questions. – Long complicated questions. – Interrogation type of questions. – A loaded questions – implied judgement. Questioning Techniques Hazard and Operability (HAZOP) Ahmed Eltayef
  • 68. 67 HAZOP leader • Plan sessions and timetable • Control discussion • Limit discussion • Encourage team to draw conclusion • Ensure secretary has time for taking note • Keep team in focus • Encourage imagination of team members • Motivate members • Discourage recriminations • Judge importance issues Responsibility of HAZOP Team Members Hazard and Operability (HAZOP) Ahmed Eltayef
  • 69. 68 Checklist for HAZOP Leader • Always prepare study program in advance. • Agree on the format or form to be used. • Prepare follow up procedures. • Brief members about HAZOP during first meeting. • Stop the team trying to redesign the process. • HAZOP is a team exercise. Do not let anybody (including the leader himself to dominate). Hazard and Operability (HAZOP) Ahmed Eltayef
  • 70. 69 Checklist for HAZOP Leader • If conflict arises, handle with care. • Avoid long discussions by recording areas which need to be resolved outside meeting. • Leader must be strong, yet diplomatic. • Speak clearly. Make you point. • Better have experience working as team member previously. • Do not skip anything….some time small things may cause big accident. Hazard and Operability (HAZOP) Ahmed Eltayef
  • 71. 70 HAZOP Secretary • Take adequate notes • Record documentations • Inform leader if more time required in taking notes • If unclear, check wording before writing • Produce interim lists of recommendations • Produce draft report of study • Check progress of chase action • Produce final report Responsibility of HAZOP Team Members Hazard and Operability (HAZOP) Ahmed Eltayef
  • 72. 71 Process Engineer • Provide a simple description • Provide design intention for each process unit • Provide information on process conditions and design conditions • Provide a simple description • Provide design intention for each process unit • Provide information on process conditions and design conditions Responsibility of HAZOP Team Members Hazard and Operability (HAZOP) Ahmed Eltayef
  • 73. 72 Mechanical Design Engineer • Provide specification details • Provide vendor package details • Provide equipment and piping layout information Instrument Engineer • Provide details of control philosophy • Provide interlock and alarm details • Provide info on shutdown, safety features Responsibility of HAZOP Team Members Hazard and Operability (HAZOP) Ahmed Eltayef
  • 74. 73 Plant Engineer or Manager • Provide information on compatibility with any existing adjacent plant • Provide details of site utilities and services • Provide (for study on existing plant) any update on maintenance access and modifications Shift Operating Engineer or Supervisor • Provide guidance on control instrumentation integrity from an operating experience view point • Provide (for study on existing plant) information on plant stability at the specified control parameters • Provide information on experienced operability deviations of hazard potential Responsibility of HAZOP Team Members Hazard and Operability (HAZOP) Ahmed Eltayef
  • 75. 74 Chemist • Provide details of process chemistry • Provide details of process hazards (polymerisations, byproducts, corrosion etc) Project Engineer • Provide details of cost and time estimation and also budget constraints. • Ensure rapid approval if required Responsibility of HAZOP Team Members Hazard and Operability (HAZOP) Ahmed Eltayef