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Hazard is the potential for harm.
A hazard is often associated with a
condition or activity that can cause
undesired consequences such as
injury or illness if left uncontrolled.
Basically, a hazard can cause harm
or adverse health effects to
individuals or to organizations as
property or equipment losses.
1) Chemical hazards
Chemicals can affect skin by contact.
Chemicals can also enter our body
either through the inhalation or
digestive system if air is contaminated
with chemicals, vapor, mist or dust.
The accumulation of chemicals in or on
our body will cause acute (immediate)
effect or chronic (long-term) effect.
2) Physical hazards
Physical hazard will cause injury
risks on our body.
This category includes the hazards
from working in confined spaces,
being hit by flying objects, caught in
explosions, hurt by collapsing
machinery, falling from heights and
tripping on obstacles.
3) Biological hazards
Biohazards refer to biological substances
that pose a harm to the health of living
Sources of biological hazards may include
insects, bacteria, fungi, plants, worms,
animals and viruses.
These sources can cause a variety of
health effects ranging from skin irritation
and allergies to infections, cancer and so
4) Ergonomic hazards
Ergonomic hazards refer to workplace
conditions that pose the risk of injury to
the musculoskeletal system of the worker.
These injuries can be caused by
performing repetitive and forceful
movements and awkward postures that
arise from improper work methods and
improperly designed workstations, tools,
5) Noise hazards
Excessive noise can disrupt
concentration, interfere with
communication and result in loss of
High impact noises are particularly
Noise can also mask out signals and
affecting communication with others.
in a process
Result of a hazard
analysis is the
different type of
hazards that may
arise from a system
or its environment
focuses on job
tasks as a
way to identify
by a product,
Technique to identify the
dangers of specific tasks in order
to reduce the risk of injury to workers.
Focuses on the
p between the
worker, the task,
the tools, and the
of the equipment
under control and
leading to the
Examine the job and determine the
Identify tasks likely to present
Identify and assess hazards
Determine and devise controls
Develop safe work procedures if
hazards cannot be eliminated
Identifying The Hazards
Identify the hazards of each step.
For each hazard, ask:
What can go wrong?
What are the consequences?
How could it arise?
What are other contributing
How likely is it that the hazard will
Hazard may be realized or unrealized
Realized hazard – has happened in the
past and can therefore be identified
Unrealized hazard – is a potential for a
hazardous situation that has not
happened yet but can be recognized by
analyzing the characteristic of an
environment or failure modes of
Hazard analysis methods
Process Hazard Analysis
Event Tree Analysis
Failure Modes And Effect
Fault Tree Analysis
Hazard And Operability Studies
1) PROCESS HAZARD ANALYSIS
A systematic method designed to identify
and analyze hazards associated with the
processing or handling of highly
-The potential causes and consequences
of fires, explosions and releases of toxic
- the equipment, instrumentation, human
actions and other factors which might
affect the process.
Processes Are First
-All PHA must
completed as soon as
- PHA must be updated
at least every five years
2) Event Tree Analysis (ETA)
ETA defines the consequential
events which flow from the
primary ‘initiating’ event.
Event trees are used to
investigate the consequences of
loss-making events in order to
find ways of mitigating rather
than preventing losses.
3) Failure modes and effect
To identify which failures in a system can
lead to undesirable situation.
Particularly suited to electrical and
Result are strongly dependent on
analyst’s understanding of the failure
Effects of failure modes can be quantified
4) Fault tree analysis (FTA)
To evaluate the economic justification
for carrying out improvement to a
FTA works back from the undesired or
“top event” to the contributing
causes(backward reasoning logic
To identify the causes of top event
Is proving to be a very useful tool to
depict and maintain an up-to date, real-
time working risk management system
enthralled in daily operations (e.g.
These diagrams combine the inductive
and deductive reasoning of logical
diagrams (e.g. ETA, FTA) to identify the
basic causes and consequences of
6) Hazard and Operability Study
A structured and systematic method that
identifies equipment that is being used in
a way that it was not designed to be, and
which might create hazards and
HAZOPs are usually conducted by multi-
skilled team that studies piping and
Each pipeline and vessel is evaluated for
certain limitations and deviations in flow,
temperature, pressure, etc.
Controlling the Hazards
The order of precedence and
effectiveness of hazard
control is the following:
1. Engineering controls.
2. Administrative controls.
3. Personal protective
1) Engineering Controls
Engineering controls include the
Elimination/minimization of the
Substitution of equipment or process
to decrease hazard
Isolation of the hazard with
interlocks, machine guards, blast
shields, or other means; and
Removal or redirection of the hazard
such as with local and exhaust
2) Administrative Controls
Administrative controls include the
Written operating procedures, work
permits, and safe work practices;
Exposure time limitations (used most
commonly to control heat stress and
Monitoring the use of highly
Alarms, signs, and warnings;
Buddy system; and training
3) Personal Protective
Personal Protective Equipment is acceptable
as a control method in the following
When engineering controls are not
feasible or do not totally eliminate the
While engineering controls are being
When safe work practices do not provide
sufficient additional protection; and
During emergencies when engineering
controls may not be feasible.
Case Study of Hazard
Fire at Formosa Plastic Corporation:
Evaluating Process Hazard
This case study describes a fire and
series of explosions in an olefins
production unit located in Point
Comfort, Texas due to hydrocarbon
16 employees were injured and 1
The fire burned for 5 days.
At 3:05 PM on October 6, 2005, a trailer being
towed by a forklift snagged and pulled a small
drain valve of a liquid propylene system.
Vaporized propylene forming a large flammable
Operators began to shut the plant down and
attempt to isolate the leak. But, the attempt was
At 3:07 PM, the vapor ignited and create an
explosion. As a result, two operators were
burned and fire reached more than 500 ft in air
as shown in figure 1.
The fires burned for five days and about 7
million gallons of water were used to cool vessel.
At 9:00 PM, Highway 35 that run
adjacent to the Formosa complex and
through Point Comfort was closed. A
shelter-in-place was provided for the
Point Comfort community.
It was recorded about 20 local
residents need medical evaluation at
Figure 2 shows the view of the
damaged plant from Highway 35.
Figure 3 shows the Olefin II unit ( one
of the 17 units) which the fire and
Figure 2 : View of the Damaged Plant
from Highway 35
A worker driving a forklift towing a trailer
under a pipe rack moving backward
between two column to turn around.
When the worker drove forward, the
trailer caught on a valve and stick out a
strainer in propylene piping system.
The trailer pulled the valve and associated
pipe (Figure 4) out of the strainer and
leaving 1.9 inch diameter opening.
Pressurized liquid propylene rapidly
escaped through the opening and partially
vaporized creating both of propylene
liquid and rapidly expanding vapor cloud.
The forklift driver and other contractors saw
the release and evacuated.
An operator heard and saw the release and
notified the control room.
The operators closed control valves and
began to shut down the unit as well as pump
from motor control center to slow the leak as
he saw the vapor cloud.
The vapor cloud ignited and operators left the
unit and declared a site-wide emergency.
A large pool fire burned under the pipe rack.
The Formosa ERT arrived and took command
of the incident response.
The fire was extinguished about 5 days.
CAUSES OF INCIDENT
Figure 6 shows the propylene piping
involved in this incident stick out into an
open space and no impact protection.
Figure 7 shows passive fire protection was
installed on only three of four support
column rows and the columns that
supported the pressure relief valves and
emergency vent piping had no
PROCESS HAZARD ANALYSIS
Figure 8 shows the protection of fire
Figure 9 shows the lack of protection
where the impact and release occurred.
Remote equipment isolation is done by
the operators by isolating minor leaks
with local valves.
Figure 8 : Protection of Fire Fighting Equipment
When performing a hazard analysis, facility
sitting analysis or pre-startup safety review,
vehicle impact and remote isolation
catastrophic releases should be investigated.
The use of flame resistant clothing may limit
the severity of injury to employees who work
in plants with large inventories of flammable
gases and liquids.
Evaluate the applicability and use of current
safety standards when designing and
constructing a chemical process plant.
Fire at Formosa Plastics Corporation:. Case
study, Washington: CSB publications, 2006.
Hazard Analysis Methodologies.
(accessed March 27, 2015).
Job Hazard Analysis. 2002.
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Types of Hazards.
301/types-of-hazards/ (accessed March 23,