3. Simulation of LPG release
• The accident that occurred in the railway station of
Viareggio (Italy) on June 2009
• A freight train carrying LPG went of the rails, five out of
fourteen wagons are derailed and overturned
• A hole formed in the first tank car due to the impact with a
signaling stake
• The pressurized LPG was released as a two-phase jet
(liquid phase and dense gas)
• The liquid phase formed a boiling pool on the ballast
• The dense gas dispersed in the atmosphere
• The dense clouds spread and moved towards the
neighboring house then it was ignited and exploded.
• 31 people died and many people were injured in fire.
4. Qualitative description of the
Accident
• On June 29th
2009 at 11:48 pm a train loaded with LPG
went off the rails while it was crossing the station of
Viareggio.
• A tank wagon was damaged and the released LPG spread
around, finally exploded and burnt out.
• Thirty one people died and more than thirty people were
seriously injured.
• The train transported 14 cars with a nominal capacity of
110m3
and each loaded with 45 ton of LPG
• When the train came to the station the front axle of the
first wagon broke and the wagon went off the rails.
• The first car detached from the tractor, overturned, and
dragged nine more cars off the rails.
5. Qualitative description of the
Accident
• The first wagon, which derailed and overturned, was
dragged on the ballast, and crashed into a stake that was
embedded in the ground
• The impact of the tank with the stake produced a
longitudinal crack in the metal vessel about 40-50 cm long
and few cm wide.
• The drivers felt a strong jerk and they went to the window
and saw the first tank car gone off the rails.
• The drivers applied immediately the emergency brakes and
they could smell the gas.
• They had enough time to jump off the train and run away
from the LPG pools on the ballast.
6. Consequences of the
Derailment
• The pressurized LPG in the first car was released by the
hole, and started spreading and evaporating on the ballast.
• The surrounding population could hear a loud noise like a
gas emitted by a valve.
• The summer night was rather hot and the people, who lived
in the houses overlooking the station, went to the open
windows to see what was going on.
• They could see a white and short cloud of gas that was
moving towards their houses.
• Some people flew to the top storey of the building,although
many houses were two storied;
• some decided to pick up some personal belongings and
some smelt the gas and run away from home.
7. • safety distance between the railway line and the nearest
house as short as 10.44m
• Five houses collapsed due to inner explosions. Almost all
the remaining houses of Street burned due to the fire
• The fire produced by the spreading of LPG released by the
punctured wagon, could be noticed far away and exceeded
the electric grid with flame lengths as high as 20-25 m.
• Fourteen people died immediately: some under the collapse
of buildings; some due to the toxic substances released by
the fire of their houses.
• Finally, there were 31 fatalities and the last person died
exactly two months after the accident
• The overall damages that involved the population and the
infrastructures were valued 32 M€.
• The consequences of the accident would have been even
worse if the stationmaster had not stopped two passenger
trains that were arriving in Viareggio a few minutes later
8. Accident Modeling
• The release of liquid propane from the crack in the tank
• The flash of the liquid jet in the atmosphere
• The spreading and boiling of the LPG pool on the ballast;
• The dispersion of vapors emitted from the tank car and of
those evaporated
• The dilution of the gas cloud in presence of obstacles such
as the railroad borders, and the houses on the cloud path
• The ignition of gas inside the houses and the magnitude of
explosion
9. Dense Gas Dispersion
• The model of TWODEE was adapted to simulate congested
environments, i.e. to account for the presence of buildings
and/or other manmade obstacles
• Figure shows the dispersion of the cloud in the area close
to the accident and its spreading over the buildings and in
the street
t=13s t=22.6s t=48.3s t=92.7s
10. Explosions
• The evidence tells us that the explosions occurred
within the houses.
• The dense gas model discussed in the previous
section cannot simulate the penetration into
buildings.
• Consequently, we cannot determine the amount
of LPG that permeated into the houses and then
exploded.
• In addition, since there were no explosions
external to the houses,
11. Conclusion
• The dynamic analysis of the Viareggio accident
showed how vast and fast were the emission and
dispersion of the LPG cloud towards the
surrounding houses.
• It took less than 100 s for the dense-gas cloud to
reach the furthest house that eventually
exploded.
• Such a short time inhibits any emergency-
response activities aimed at reducing the
accidental outcomes.
12.
13. What is Fire?
•The First of the major hazard in the process plant is Fire
•Fire in the process industries causes more serious accidents
than explosion or toxic release
•Fire is the example of fast chemical reaction between
combustible substance and Oxygen with the evolution of heat
•Three fire requirements are Oxygen, Fuel and a source of
energy called as heat.
15. AIR
Air is required as a catalyst
Can be Oxygen from the air
OR
From the Fuel itself
16. FUEL
For a fire to start
there must be something to burn
HEAT
For a fire to start there must
be a heat or Ignition source
17. Types of Fire
Fires are classified by the fuel they
burn
•Class A
•Class B
•Class C
•Class D
•Class K
18.
19. Some Effects to remove the
Fire
Starving Effect
Removal of Fuel from fire is known as
starving effect
Blanketing Effect
Removal of oxygen is known as
blanketing effect
Cooling Effect
Cooling down from the optimum
temperature is known as cooling effect
20. Products of Fire
• Smokes
• Heat
• Flames
• Sound
• Pressure – Effect on airs and other
limbs during explosion
21. Classification of Fires
Process Industries
• Vapour cloud fires
Fire with no explosion
Fire resulting from explosion
Fire resulting in explosion
• Fire Balls
22. • Jet flames
• Liquid Fires
Pool fire
Running liquid fire
23. • Solid fires
Fires of solid materials
Dust fires
• Warehouse fires
• Fire associated with oxygen
Causes for Industrial Fire
Smoking
Chemicals
Dirt and Untidiness
Flammable liquid
24. Fire Spread
The Heat liberated by the fire also causes the
surrounding materials to warm up, The heat
transfer is accomplished the following three factors
•Conduction
•Convection
•Radiation
25. Conduction
• Direct Thermal energy transfer due to Contact
• Materials conduct heat at varying rates
• Metals are very good conductors, while concrete
and plastics are very poor conductors
26. Convection
• Heat Transfer through a liquid or gas
• Caused by the density difference of the hot
molecules compared to the cold molecules
(eg.Boiling of water)
• Hot air, Gases expand and rise
27. Radiation
• Electromagnetic wave transfer of heat to an
object
• Waves travel in all directions from the fire and
may be reflected or absorbed by the surface
• Absorbed Heat raises the temperature of the
material beyond its ignition point and causing to
ignite
28. Types of Extinguisher
• Water Fire Extinguisher
The Cheapest and most widely used fire
extinguisher, used for class A fire and not suitable
for class B (liquid) or electrically involved
• Foam Fire Extinguisher
More expensive than water, but more
versatile. Used for classes A and B fires. Foam
spray extinguishers are not recommended for the
fires involving electricity, but safer than water if
sprayed on to live electrical apparatus.
29. Dry Powder fire extinguisher
•It often termed as multi purpose extinguisher.
•It can be used for all classes of A,B,C fire
•Best for running liquid and gas fire
co2 fire extinguisher
carbon di oxide is ideal for fires involving in
electrical apparatus and extinguish class B liquid
fires.
30. Fire safety devices
• Fire alarm
A manual alarm system which consist of
break glass units and alarm sounders
connected to a control panel.
• Smoke detector
An automatic system compraises of
smoke and heat detectors and it is also
connected to the control panel. It
provides early warning of the fire
incident.
31. • Water sprinkler
Water sprinkler is a component of
fire sprinkler system, that discharges
water when the effect of fire is detected
• Water Hose pipe
A fire hose is a high pressure hose
that carries water or foam to a fire to
extinguish it. It can attach to a
building standpipe or plumbing
system.
33. Introduction
• Fault tree analysis was originally developed in
1962 at Bell laboratories by H.A. Watson
• FTA is deductive analysis approach for resolving
an undesired event into its causes
• Logic diagrams and Boolean algebra are used to
identify the cause of the top event
• The logic diagrams are called as fault tree and it
is constructed to show the event relationship
34. Need for FTA
• To identify the cause of failure
• Monitor and control safety performance of a
complex system
• To identify the effects of human error
The Fault Tree
• It is a logical model of the relationship of
undesired event to more basic event
• The top event of the fault tree is undesired event
• Middle events are intermediate events and the
bottom are basic events.
• The relationship of the events are shown by gates
35.
36.
37.
38. Advantages
• User could select the top event to be specific to
the failure of interest
• Minimal cut sets with a product of 4 or more
independent failure will increase the reliability of
the system
• Provide qualitative and quantitative analysis
• Softwares are available to determine the cut sets
and to calculate the failure probabalities
39. Disadvantages
• Can be enormous (Thousands of intermediate
events)
• Not necessarily all failure modes are considered
• Need experienced engineers
• External events not correctly treated
Application
• Used in the field of safety engineering and
reliability engineering to determine the probability
of a safety accident or a system failure..
41. Introduction
• ETA evaluates potential accident outcomes that
might result following an equipment failure or
process upset known as an initiating event.
• It is a “forward-thinking” process, i.e. the analyst
begins with an initiating event and develops the
following sequences of events that describes
potential accidents.
42. Guidelines
1.Identify an initiating event of interest.
2. Identify the safety functions designed to
deal with the initiating event.
3. Construct the event tree.
4. Describe the resulting accident event
sequences
44. Identify the safety functions
designed to deal with the
initiating event
• Safety system that automatically respond
to the initiating event.
• Alarms that alert the operator when the
initiating event occurs and operator
actions designed to be performed in
response to alarms or required by
procedures
