HAZOP study which is very much helpful to identify hazards in the premise & mitigate it.

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HAZOP Training
for CFCL- Urea-I
unit.
Consultancy
Training
Testing

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HAZOP: HAZARD & OPERABILITY STUDY
 A comprehensive guide about HAZOP: purpose, study and analysis
process, importance to different industries, and an efficient tool to
help streamline the HAZOP process.
 The primary objective of the HAZOP study is to identify and evaluate
HSE hazards due to process deviations/system failures/human error
and to identify operability issues which, although not hazardous,
could compromise the plant’s ability to achieve its design intent and
productivity.
 The secondary objective of the HAZOP is to confirm the adequacy of
detection of deviations and controls safeguarding the process.

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Origin Of HAZOP
1. Initially prepared by Dr H G Lawley and associates of ICI at Wilton in
1960’s.
2. 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).
3. In 1977, Chemical Industries Association published the edited
version.

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Where is HAZOP applicable?
 HAZOP study procedure is applicable to every
definite operational sequences in planned and
existing systems. HAZOP Analysis is most
effective when held during the conceptual design
stage in which recommendations impacting the
general design may be fabricated.
When is HAZOP done
 As depicted in the below held Flow Chart,
HAZOP Analysis should be completed in stages
inside a risk management project. Generally
HAZOP analysis is initiated immediately upon a
new process or a process that has brought a
change in the working environment.

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Objective of HazOp
1. Identify cause and the consequences of hazards of the complete
system by brain storming among team members.
2. List out all the hazards/recommendations in a standard format.
3. Compliance of recommendation prior to start up of the plant/as
early as possible.

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HAZOP Methodology
 The HAZOP technique consists of a systematic analysis of the design
in order to assess any operability problems or process-related
hazards. The HAZOP Review is developed reviewing each P&ID
using a structured step-by-step approach that allow to
comprehensively analyses the whole process via suitable
guidewords, used to identify credible deviations from the design
intent.
 The method identifies hazards and suggests possible accident
sequences resulting from such hazards; innovative thinking then
identifies the consequences of these scenarios.

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HAZOP Methodology

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HAZOP Procedure

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Causes & consequences
 Causes: The reasons why the deviation could occur. Several causes may be
identified for one deviation. It is often recommended to start with the
causes that may result in the worst possible consequence.
 Consequences: The results of the deviation, in case it occurs. Consequences
may both comprise process hazards & operability problems, like plant
shutdown or reduced quality of the product. Several consequences may
follow from one cause &, in turn, one consequence can have several
causes.

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Standard Guidewords
Deviation Guide Word Parameter
No/Low Flow No/Low
More Flow More/High
Reverse Flow Reverse
More/High Pressure More/High
Low Pressure Low Includes vacuum
More/High Temperature More/High
Low Temperature Low
High Level High Includes interface high
level
Low Level Low Includes loss of level,
interface low level and
loss of interface level
Contamination/Composition
Change
Composition
Start-up/ Shutdown /
Commissioning
Others

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Risk Matrix

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Benefits of HAZOP Study
 Potential deviations from intended design
function are identified and corrected
 Health, safety and environmental process
and equipment hazards are revealed
 Actions for necessary process or
instrumentation improvements can be
planned
 Action responses are auditable by
management and legislative
inspectorates
 Can be applied to a wide range of types
of system

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When to Perform a HAZOP
HAZOP studies may be used more extensively, including:
1. At initial stage (design drawings are available).
2. When final P&ID’s are available.
3. During Construction and Installation.
4. During Commissioning.
5. During Operation.
6. During Modifications.
7. During Shutdown.
8. During Dismantling

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Documents Required for HAZOP Study
• PFD / PFSs (Process Flow Diagram/ Process Flow Schemes)
• P&ID / PEFS's (Piping & Instrument Diagrams/ Process Engineering
Flow Schemes)
• Basis of Design.
• Operating, Control and safeguarding philosophy.
• Plot plans & Hazardous area classification drawings.
• Cause & Effect diagrams.
• Process description
• Chemical hazard data (MSDS).
• Safety procedure documents
• Materials Of Construction (MOC)
• Electrical classification (HAC)
• Critical equipment list & etc…

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HAZOP Team Composition
• HAZOP CHAIRMAN
• HAZOP SCRIBE
• PROJECT or SITE PROCESS ENGINEER
• PROJECT or SITE ELECTRICAL, CONTROLS
and INSTRUMENTATION (EC&I) ENGINEER
• SENIOR OPERATIONS REPRESENTATIVE
• PROJECT or SITE PROCESS SAFETY
ENGINEER
• MAINTENANCE / MECHANICAL ENGINEER
• LAB CHEMIST

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Sample

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Advantages of HAZOP
1. Reduce design & operational faults.
2. It helps to modify the Operations in view of possible accidents which
may occur due to inherent error or manual error.
3. Systematic examination.
4. Covers human errors.
5. Covers safety as well as operational aspects.
6. Multidisciplinary study.

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Premise Conditions For HAZOP
Execution
Some of the common HAZOP premise conditions are given below.
 The simultaneous occurrence of more than one incidence that could
result in an accident or hazards will not be discussed if the causes are
unrelated.
 A single check valve is considered to be adequate, unless a potential
exists for backflow of high pressure fluid to create pressures that
exceed the test pressure of the equipment.
 Problems due to operator's negligence will not be discussed.
However, problem related to common human error may be considered
in the hazop.
 No sabotage will be considered.
 Problem due to natural calamity such as Food Storm, Earthquake etc

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 Problem due to the foreign object falling from sky such a falling of
comet, missile spacecraft etc will not be discussed.
 Equipments / items are to be considered suitable for the design
condition specified in the design documents.
 Piping work is done as per P&ID and in accordance with the piping
specification.
 Mechanical protection device used in the plant for ultimate safety such
as safety valve rupture disc etc is expected to work without any
apprehension.
 In the hazop session, no quantitative analysis will be done for the
hazards.
 In case of reviewing a system which has two trains, only one train
should be studied.
 Simultaneous failure of more than one independent protection device

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Following are to be considered as safeguard / protection.
1. Interlock/Shutdown System/Trip/Protection
2. Alarm system for operators' action
3. Mechanical protection devices.
4. Sample monitoring System
5. Operating Instruction and operating manual

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Case Study
 Accident: BP America (Texas City) Refinery Explosion
 Location: Location: Texas City, TX
 Accident Type: Oil and Refining - Fire and Explosion
At approximately 1:20 p.m. on March 23, 2005, a series of explosions occurred
occurred at the BP Texas City refinery during the restarting of a hydrocarbon
isomerization unit. Fifteen workers were killed, and 180 others were injured.
Many of the victims were in or around work trailers located near an
atmospheric vent stack. The explosions occurred when a distillation tower
flooded with hydrocarbons and was over pressurized, causing a geyser-like
release from the vent stack.

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Video for reference
 Texas Refinery Explosion

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Root cause
 No flare to safely combust flammables entering the blowdown system.
 lack of automated controls in the splitter tower triggered by high-level,
which would have prevented the unsafe level
 Inadequate instrumentation to warn of overfilling in the splitter tower.
 Malfunctioning instruments and equipment were not repaired prior to
startup
 Did not have an effective vehicle traffic policy to control vehicle traffic into
hazardous process areas or to establish safe distances from process unit
boundaries.
 Ineffectively implemented their PSSR policy; nonessential personnel were
not removed from areas in and around process units during the hazardous
unit startup

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Why SIGMA HSE
• Sigma-HSE offer onsite and online HAZOP strategies and solutions with our
experienced technical consultants.
• Our leaders have a vast array of knowledge and expertise in industrial
process safety which they bring to HAZOP leadership.
• We have undertaken studies across the full range of the processing
industries (chemicals, pharmaceuticals, explosives, food & hygiene, waste,
onshore oil & gas, etc) and processing operations (chemical reaction
technology, storage and transfer systems, incineration systems etc).
• Our team of experts are committed to helping you ensure and maintain
compliance without the exorbitant fees and delay to your operations.

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OUR PRESENCE
 Technical Offices
 New Delhi, Mumbai, India
 Winchester, UK
 Laboratories
 Process Safety Lab, Winchester, UK
 Process Safety Lab, Delhi, India
 The Environmental Laboratory (ELAB), UK