Hazard Identification and Risk Assessment
by N.P.Rao.(CHIEF MANAGER(F&S)
PAPER PRESENTED IN ICQESMS(INDIAN CONGRESS ON QUALITY,ENERGY,ENVIRONMENT AND
SAFETY MANAGEMENT SYSTEMS CONDUCTED BY JADHAVPUR UNIVERSITY AND CBWE AND
GOT EXCELLENT AWARD
For any industry to be successful, it has become essential to identify the Hazards ,to assess the associated
risks and to bring the risks to tolerable level. Recognising this, IFFCO-AONLA is continuously putting efforts
for controlling the risks which are arising from various Hazards such that loss to Human life and property is
negligible or zero. Its continuous best efforts to identify the Hazards and to bring the risk levels to tolerable
level in the organization are recognised by several Government and safety regulating bodies. This paper
describes briefly about various types of Hazards and their associated risks, how they are being controlled
effectively through risk analysis at IFFCO – Aonla unit
In all plants, hazards and risk are identified time to time by using modern techniques. IFFCO Aonla unit is
OHSAS –18001 certified company. So in all departments /section risk and hazards are find out by proper risk
assessments. During this severity at various levels matched with probability level. And find out the case of
intolerable, substantial, moderate and tolerable risk. Accordingly control measures at the place checked.
Documentation done and records are maintained. .
At IFFCO Aonla unit, HAZOP, HAZAN study, Dow index, Risk Analysis, FMIA, Fault Tree Analysis are carried
out at its inception level..At IFFCO Aonla unit, various risk assessment procedures are followed. This has been
done by Dow Index method and Consequences methods. At the same time when any process modification
done/needed, then also proper HAZOP studies and any other risk analysis studies are carried out to assess
the risk due to the effect of modification.
Now as IFFCO Aonla unit is OHSAS –18001 certified company, in all sections/plants proper hazard and risk
assessment procedures and documentation done. Time to time, plant/section updates of this done and audited
by other sectional persons. And again compliance incorporated.
1.0.0 To effectively implement the safety systems , a structured approach has been drawn out to minimize
the hazards and risks . This involves the following :
REPORTING/INVESTIGATING/ANALYSIS OF ACCIDENTS, DANGEROUS
OCCURRENCES AND NEAR MISSES.
When any accident occurred in plant premise, the concern area shifts in-charge informed his higher
officers as well as fire and safety section regarding this. Immediately accident/dangerous occurrence
investigation committee consisting of senior officers from affected area, fire and safety section, factory
safety officer and medical person set up. This committee starts immediately investigation without
delay. It also preserves all facts and finding and reports of for future reference.
IFFCO AONLA UNIT Y-AXIS ACCIDENT FREE MILLION HOURS
Free Man 16
days 910 days( Cont.)
400 Accident Free Mandays 6
0 2 1.9 1
26.10.1997- 02.06.2000- 01.09.2002- 01.01.2003- 28.08.2004- 0 26.10.1997- 02.06.2000- 01.09.2002- 01.01.2003- 28.08.2004-
31.05.2000 08.06.2002 31.12.2002 22.08.2004 15.02.2006 31.05.2000 08.06.2002 31.12.2002 22.08.2004 15.02.2006
Accident Free Period
IFFCO AONLA UNIT
Y-AXIS –ACCIDENT FREE MAN DAYS Million Man
1000 14 12.27
800 10 7.83 Accident free
737 Million Man-
600 700 6
26.10.1997- 02.06.2000- 01.09.2002- 01.01.2003- 28.08.2004-
31.05.2000 08.06.2002 31.12.2002 22.08.2004 15.02.2006
0 26.10.1997- 02.06.2000- 01.09.2002- 01.01.2003- 28.08.2004- Accident Free Period
31.05.2000 08.06.2002 31.12.2002 22.08.2004 15.02.2006
X-AXIS ACCDIENT FREE PERIOD
Now we see what type of risks and how they are being handled through some models of risk
analysis in IFFCO –AONLA unit.
PROCESS & SAFETY–RELATED DATA FOR INDIVIDUAL PROCESS STAGES :
Physical and Health Occupational Hazards in any large scale Chemical /Hydrocarbon Processing
Industry (CPI/HPI) like our can be broadly classified into the following categories:
i. Mechanical Risks
ii. Electrical Risks
iii. Fire/Explosion Risks
iv. High /low Temperature Exposure Risks
v. Toxic/Carcinogenic Chemicals Exposure Risks
vi. Corrosive/Reactive/Radioactive Chemicals Exposure Risks
The first two types of risks are of universal nature associated with any industrial activity and not
specific to a particular plant or process. Mechanical risks which are generally encountered are
injuries to the head, Limbs, eyes, etc usually as a results of negligence on the part of
operating/maintenance personnel in the use of improper tools, bypassing prescribed safety
procedures neglect of personal protective wear and risks associated with rotating machinery as
well as risks associated with high-energy release from compressed gases. Electrical risks which
result in shock and/or burns are most often a consequence of poor maintenance, ingress of dust or
moisture, handling by unauthorized personnel and use of improper/substandard hardware.
Other categories of risks associated with specific plants are detailed here under.
Ammonia Plant :
The manufacture of anhydrous liquid ammonia involves processing of hydrocarbons under high
temperature, high pressure conditions in the presence of various catalysts, chemicals etc. Typical
risks are as follows:
Fire /Explosion Glands/seal leaks in valves, pumps, compressors handling hydrogen,
natural gas, naphtha, synthesis gas etc.
Hose/pipe failure, leakage from flanged joints carrying combustible
gases, vapours, liquids.
Fire box explosions in furnaces.
High/Low Temp. Burns due to contact with hot surfaces of pipelines, equipments, etc.
Exposure Risks or leaking steam lines, process fluids at high temperature.
Frost bite due to contact with anhydrous liquid ammonia at -33 deg. C
Burns due to contact with pyrophoric catalyst.
Toxic Chemicals Asphyxia due to inhalation of simple asphyxiants like CO2 , N2, H2,
Exposure Risks CH4, naphtha etc. and chemical asphyxiants like CO, NH3, Nickel
carbonyl, V2O5, Hydrazine, NOx, SOx, H2S etc.
Acute toxicity due to inhalation of catalyst dusts containing heavy
metals like Ni, Cr, CO, Mo, Fe, Zn, Alumina etc. and silica gel
molecular sieves, insulation fibers/dusts.
The manufacture of urea involves reaction of Ammonia and Carbon dioxide under high
temperature & pressure and subsequent recovery and concentration of the solution at various
pressure stages. Typical risks are as follows :
Fire / Explosion Risks Ammonia leaks from glands / seals Risks involves, pumps or
flanged joints piping resulting in formation explosive mixtures in
Accumulation of H2 may take place in HP Section in case CO2
purity from Ammonia Plant is not within allowable limits. Ignition
of this accumulated H2 can occur due to dissipation of static
High / Low Refer to risks in Ammonia Plant
Toxic Chemicals Asphyxia due to inhalation of simple Exposure Risks asphyxiants
Exposure Risks like CO2 and N2 and chemical asphyxiant, NH3. Solution of
Urea, Ammonium carbamate and ammonium carbonate
containing high NH3 content.
Irritation due to inhalation of urea dust.
Corrosive / Radioactive Severe burns, damage to eyes, skin and body tissues due to
Chemicals Exposure contact with anhydrous ammonia, conc. Urea and Ammonium
Risks carbamate solutions.
The captive Power Plant involves generation of steam in N.G./Naphtha-fired boilers and utilizing
the steam in Urea and Ammonia plants. Typical risks are as follows :
Fire / Explosion Risks Explosion and fire risks associated with storage and handling of
B Class (Naphtha) and Natural gas handling pipelines (Refer
off site Facilities).
Fire Box explosion in Boiler
Flammable Material Lower Upper Temp. °C
High / Low Temp. Burns due to contact with hot surfaces of pipelines,
Exposure Risks equipments, etc. or leaking steam lines.
Toxic Chemical Asphyxia due to inhalation of SOX and Nox.
Exposure Risk Irritation due to inflammation caused by inhalation of Natural
gas and the Naphtha vapors.
The permissible exposure limits for cyclohexylamine coal dust / fly-ash are given below :
The offsite facilities, as already described at the very outset, consist of integrated units for water
and effluent treatment, inert gas generation, cooling towers, storage of petroleum products and
ammonia, supply / distribution of utilities like compressed air, water, etc. Potential risks in the
above offsite facilities are essentially on account of handling of corrosive, toxic and reactive
chemicals as well as inflammable petroleum products.
Fire / Explosion Risks Gland / Seal leaks in valves, pumps, compressor, handling naphtha,
N.G., ammonia hydrogen, syngas etc.
Hose / pipe failure, leakage from flanged joints in pipes conveying
petroleum products, ammonia, hydrogen, syngas, etc.
Leakage of petroleum products during tanker unloading operations.
Overflow from storage tanks.
Overheating / pressurization of storage tanks.
Improper earthing / lightning protection of storage tanks and
Improper sealing of floating roof tanks.
In adequate / improper breather valves leading to tank failures.
Fire Box Explosion in cracker Furnace.
Critical data for flammable materials stored / handled in off sites has already been furnished under
Ammonia Plant and Power Plant.
High / Low Temp. Burns due to contact with hot surfaces of pipe lines, equipments, etc
Exposure Risks or leaking steam lines.
Heat radiation burns from high intensity flames from the flare stack.
Frost bite due to contact with anhydrous liquid ammonia at – 33 °C
Toxic Chemicals Asphyxia due to inhalation of simple asphyxiants like N2, H2,
Exposure Risks Naphtha, etc. and Chemical asphyxiants like Cl2, NH3, NOx, Sox,
Toxicity due to inhalation of catalyst dust containing heavy metals like
Ni, Pd, Alumina etc. and perlite / insulation fibers, silica gel dust.
Data on Threshold Limit Values Limits for most of the above toxic Chemicals and dusts
encountered in off sites has already been furnished under Ammonia Plant. Data for Cl2 are as
Corrosive Chemicals Severe burners, damage to eyes, skin & body tissues due to
Exposure Risks contact with corrosive chemicals like anhydrous liquid
Ammonia, Sulphuric acid, Hydrochloric acid, etc.
The bagging plant encompasses storage, packing, loading and dispatch activities for product urea
via road or rail. Typical risks in this plant are as follows :
Fire Risks Fire hazards due to storage of bulk quantity of polyethylene –
lined jute bags or HDPE bags which are easily combustible.
Chemicals Exposure Risks Irritation due to inhalation of urea dust and jute fibers.
S.No Name of Chemical Form under normal condition Expected form of
1. Ammonia Liquid state at – 33 °C temp. & Vapour / Gaseous form.
Vapour / Gaseous form.
2. Chlorine Liquid at ambient temp. & 17.0
Kg/cm² pressure. Vapour
3. Naphtha Liquid at ambient temp. & pressure.
Liquid at ambient temp. & pressure.
4. Hydrochloric Acid Liquid at ambient temp. & pressure. Acid fumes
Gaseous at ambient temp &
5. Sulphuric Acid Pressure Gaseous Form
6. Natural Gas
INFORMATION ON THE PRELIMINARY HAZARD ANALYSIS
Types of Accident
It is clear that during the course of Urea manufacture, furnaces, reactors, moving machineries,
material handling, cranes, chain, pulley blocks, wire ropes, chemicals, Rail wagons, etc. are
involved. Past reportable accidents are related to these agencies.
Type of personnel injuries indicates burn, cut, bone fracture burn injury etc. A brief resume of types
of accidents may happen are as follows ;-
1. Burn injury due to handling cleaning of burners in furnaces.
2. Fire accidents in furnaces leading to property damage.
3. Burn injury accident due to attending electrical faults.
4. Burn injury accidents due to handling of acids / alkalies.
5. Hit / cut type accidents due to various maintenance jobs. For reference purposes and
internal report titled “Safety Performance at a glance” is enclosed as Annexure 5.
System Elements or Events that can lead to a major Accident
All the section / plants of IFFCO Aonla unit are constructed and designed taking care of all relevant
safety measures possible. However the system elements such as Ammonia storage, Naphtha
storage, Chlorine tonners, Ammonia Plant area, Urea Plant HP section are some of them which
can lead to a major accident.
Although, Fire, explosion and release / leakage of toxic chemicals may lead to major accident, all
necessary safety measures have been duly incorporated in the plant design and regular up
gradation of safety appliances is carries out.
Urea manufacturing process involves many chemicals such as NG, as feed stock, Ammonia as an
intermediate product and chlorine, hydrochloric / sulfuric acids, as water treatment chemicals.
Furnaces, High pressure vessels, Reactors, pipe lines, storage tanks are also involved in the
course of Urea and Ammonia manufacturing. Handling and storage of these Hazardous chemicals
and their use in the process may leak to a hazardous situation.
Failure Mode Analysis
There are various modes in which flammable and toxic chemicals can leak into atmosphere
causing adverse affects. It may be small leaks from gaskets of the flanged joints, or guillotine
failure of a pipeline of even catastrophic failure of the storage tank. Some typical modes of failures
and their possible causes are discussed below :
S.No. Failure Mode Probable Cause Remarks
1. Flange / Gasket Incorrect gasket Incorrect Attention to be paid during selection
failure installation. and installation of gaskets.
2 Weld failure It is normally due to poor Welding to be done by certified
quality of welds welders with right quality of welding
rods. Inspection and radiography
must also be done.
3 Pipe corrosion Some times fabrication or Pipes material of construction
erosion or failure installation leaves stress should be selected correctly.
due to stress in the pipes. Erosion or Design should take care of erosion
corrosion also are effects. And installation of pipes
sometimes the cause. should not leave any stress.
4 Over pressurization Over pressurization can Necessary procedures should be
of pipeline occur due to failure of there to prevent.
SRV or incorrect
5 Deficient Pipes design and It must be ensured that installation
installation of pipes installation is sometimes is as per correct standards
not as per appropriate completely.
6 Leaks from valve Leaks from glands, Right selection of valves and their
bonnets or failures valves maintenance should be ensured.
spindle is sometimes the
7 Instruments failure Multifarious instruments Reliability of instruments working
are used for control of must be ensured through proper
process parameters. Any selection and maintenance.
such instrument failure
can cause mishap.
8 Failures of Protective system like Reliability of protective system must
protective system SRV, bursting discs, vent be ensured highest through
header, drain lines etc. inspection and proper maintenance.
are provided to take care
of abnormal conditions.
9 Operational effort Plant operational Operating procedures must be
parameters should not be complete and strictly followed.
exceeded beyond the
10 Other failures There are external other Design and operating philosophy
reasons causing the must consider all possible reasons.
INFORMATION ON THE HAZARD ASSESSMENT
Identification Of Hazards
The following main hazards may exist in the factory under the situations given below-
High temperature and pressure.
Fire & explosions (due to inflammable / combustible materials).
Toxic and corrosive chemicals.
Toxic and poisonous gases and dust.
Electricity (Receiving / Clue ration / Distribution).
Disposal of wastes.
Work at heights.
Work in confined spaces / vessels / tank etc.
Specific jobs carried under highly hazards atmosphere (CO2, NH3, Naphtha vapours etc.).
Non working of safety devices, inter locks, failure of high RPM machineries.
Failure of boilers etc.
Any other consequences due to leak of Ammonia, Chlorine gases.
Hazards during heavy equipment handling (Crane, etc.)
However, the threats posed to the aforesaid hazards may be on account of (i) Fire or (ii) explosion
or (iii) Release of toxic or corrosive liquid / gas from their confinement.
Causes Of Major Accidents
Following Major causes may lead to major accidents :-
1. Release of Ammonia in huge quantity from storage tank.
2. Release of chlorine due to leakage / rupture in chlorine toner or its valve failure of injection
pipe failure feeding to cooling tower.
3. Fire / explosion in Naphtha tanks due to leakage, unconfirmed clouds, or boil over, etc.
4. Explosion in High pressure equipments, reactors in Ammonia / Urea Plants.
5. Fire / explosion in furnaces of Ammonia Plant and boilers in Power Plant.
Assessment Of Hazards According To Their Occurrence Frequency
Concurrency frequency (probability failure / year) for each selected failure case is given in table
9.c.1. For most of the cases the probability of failure occurrence is very less. Fire / explosion, sling
failure, safety rule failure, and injuries etc. are some cases which are considered as associated
Assessment Of Accident Consequences
A major accident may cause severe danger to life and properties. The assessment will be based
The first one will be loss of life, property damage and injuries to the scene of occurrence where the
people are working or combating with the accident control.
The offsite losses will include the loss of lives, injuries and properties damages of neighbor hood
bases on the affected area of accident or major event, if any.
Assessment Of The Possible Release Of Hazardous Chemicals Or Of Energy.
Technological Risks posed by this Fertiliser factory constitute threat to :
i) Its workers
ii) To a third party who may be present either in the factory or in its vicinity at the time of accident.
iii) Inhabitants living in the immediate neighborhood of the factory and their property.
iv) Environmental Conditions around the factory site.
The threats posed to the aforesaid entities may be on account of -
iii) Release of Toxic or corrosive liquids / gas from their confinement. The primary reason why
such a disaster may occur, in spite of all precautionary measures is that major type of
chemicals handled, are highly hazardous in nature and in substantial quantities, or
iv) A combination of more than one of such accidental phenomenon.
These risks may manifest due to accidental failures, break down or rupture of processing vessels,
equipments, storage tanks or pipelines. They may also arise due to undetected loss of
containment because of which liquid or gas contents gradually leak out in sufficient quantities to
create a hazardous situation. The loss of containment and associated hazards may be realized in
one of the following ways :
- Large scale fire in naphtha storage area due to damage to the storage tank.
- Naphtha leak from pipeline resulting into fire.
- Flash fire due to leakage of flammable gas.
- Equipment failure, pipeline failure, flange gasket failure, pump seal failure, safety relief valve
failure etc. resulting in leakage of flammable, explosive and toxic material.
- Accidents due to human errors.
- Acts of nature like earthquake, enemy air attack during war, sabotage, act of terrorism etc.
When the scale of such accident is as to cause either –
a) Severe destruction of property.
b) Multiple fatalities and other casualties and cannot be contained within the premises, a Disaster
Situation is said to prevail.
However the release of components listed below may cause hazards:-
a) Natural Gas, the feed stock for ammonia plant and
b) Hydrogen gas produced by reformation process for synthesizing Ammonia and
c) Ammonia itself, generated as an intermediate product, constitute the gravest risks both from
their nature of properties and the quantities involved.
Natural Gas is a highly flammable Gas equivalent to gasoline from fire and explosion hazard
angle, having a auto ignition temp. of 482 °C and a flammable range of 3.8 – 17 %.
Naphtha is also highly flammable liquid having flash point of -40o C and flammable range between
1 and 6%.
Ammonia is highly toxic gas its TLV being 25 ppm. It is also a combustible gas which can explode
under certain circumstances, although its lower explosive limit is rather high being of the order of
16%. It is true that two other highly flammable gases viz Carbon Monoxide and Methane are also
evolved in of the Ammonia plant. However, as these gases are immediately converted into non-
hazardous substances, they at best constitute transient risks. Besides the materials directly
involved in the manufacturing process, another extremely toxic gas viz Chlorine.
Chlorine (which has a TLV of 1 ppm) is used for treatment of water in the Cooling Towers. In-
spite of the fact, that quantity of chlorine held in the plant is almost insignificant, because of its
extremely high toxicity a leakage even in a „tonner‟ holding only 900 Kg of gas can endanger the
persons present inside the plant.
Assessment of risks posed by industrial accidents has two aspects viz.
How frequently such accidents can occur and
What could be their impact on people, property and environment.
Making a technically sound assessment of accident frequency for any individual plant is like
walking on treacherous grounds. It is true that there are various structured methods like HAZOP,
HAZAN, fault tree, Analysis Event tree Analysis etc. through which an estimate of such frequencies
can be attempted. However, no such methods can ensure that all potential accidents or top –
events would be identified, that all potential fault paths would be found and all common cause
failures covered. More-over, the adoption of such methods need use of Reliability Indices of
equipment and components of the system under study. These Reliability Indices are expected to
be furnished by the manufacturers, which is seldom the case in actual practice. No doubt generic
data could be used as a less preferable alternative. However, besides such data not being
available for every component, their use may give an entirely erroneous picture, as the real values
of such indices are greatly dependent on conditions of use, standards of maintenance etc. Even if
correct Reliability data were available, the results may not be quite accurate as accidents are
known to have taken place due to Human errors in operation and maintenance for which no
satisfactory models are yet available.
A statistical estimate of the risk could have been made if enough operating experience of the facts
was available. However, in the present case, the experience is not long enough to predict with any
degree of certainly of probability of accidents of different magnitudes, especially of that which may
cause Maximum credible loss, as such accidents are incidents of extremely low frequency. All that
can be stated with confidence is that since.
a) The process carried out in the plant is well tested.
b) The design and installation of the plant comply with recognized standards and codes of
c) All reasonable precautions are followed in respect of operation and maintenance, chances
of a major accident is of low order.
HAZARDOUS AREAS OF THE PLANT
The following areas of the IFFCO Aonla Unit are hazardous with respect to nature of materials
handled and operating parameters.
Naphtha Storage and Handling
PLANT WISE HAZARDS
The plant wise hazards due to nature of materials handled there at are given below :
Plant Hazardous Material Nature of Hazard
Ammonia Plant Natural Gas Fire
Process gas containing Fire
H2, CO, CH4 Explosion
Urea Plant Ammonia (liquid or gas) Toxic
Ammonia storage Ammonia Carbon dioxide Toxic Asphyxiant
Naphtha Storage and Ammonia Toxic
handling Naphtha Fire
D.M. Water plant Hydrochloric acid caustic lye Corrosive
Cooling Tower Chlorine Toxic
ASSESSMENT OF THE POSSIBLE DISPERSION OF RELEASED CHEMICALS
STORAGE CAPACITY OF HAZARDOUS MATERIALS
The hazardous materials stored in the plant in substantial quantities. The detail of storage capacity
for each material is given below:
Equipment Nos. Material Capacity
Naphtha storage tank (old) 2 Naphtha 6000 KL
Naphtha storage tank (new) 1 Naphtha 10000 KL
Ammonia storage Tank 2 Liquid Ammonia 10,000 Te *
Chlorine Tonners 16 Chlorine 900KG
* Though the capacities of Ammonia storage tanks are 10000 Te each , we normally store minimal
quantity of liquid Ammonia in our Ammonia storage Tanks. The storage quantity at no times
goes beyond 40% in the storage tanks. This conscious decision reduces the hazard potential.
FAILURE CASE LISTING
Keeping in view, the inventories of different hazardous material, plant process parameters etc.
following are the selected failure case which way be considered for consequence analysis. This
includes the worst case scenario i.e. catastrophic failure of Ammonia storage tanks and Naphtha
storage tanks, also leakage of ammonia from ammonia storage tank or from the system handling
ammonia, chlorine from tonners and fire in the naphtha tanks or from handling systems is identified
as the major accident hazards. This can occur as given below:
Catastrophic rupture of Refrigerated liquid ammonia or liquid ammonia spill and
Ammonia storage tank or major dispersion.
leakage from the ammonia
Chlorine leakages from the Chlorine leakage and dispersion
tonners due to valve getting
Catastrophic failure of Naphtha/ Major fire.
FO storage tanks and the
leakage catching fire.
Pipeline fracture / Nozzle failure Liquid ammonia spills at hydraulic head or pump delivery
pressure and dispersion.
Chlorine leakage at tonners pressure and dispersion
If the leakage due to pipeline fracture or nozzle failure in
naphtha and catches fire- fire incident.
Gasket failure Liquid ammonia spill and dispersion.
Chlorine leakage and dispersion.
Fire if the naphtha or FO leakage due to gasket failure and the
leakage catch fire.
System elements or events that can lead to major accident.
a. Catastrophic rupture of Ammonia storage tank or major leakage from the ammonia handling
b. Chlorine leakage from the tonners due to valve getting sheared.
c. Catastrophic failure of Naphtha/FO / Diesel storage tanks or major leakage from the handling
systems of these materials catching fire.
d. Pipeline fracture / Nozzle failure.
e. Gasket failure leading to flange leakages
Incident Quantity Released
1 Catastrophic rupture of 4000 MT Ammonia Concentration upto 500 ppm in
Ammonia storage tanks. down-wind direction upto 11000 m
2 Liquid ammonia line to 40MT Ammonia concentration upto 500 ppm in
tank failure (20%) down wind direction upto 4700ft downwind
& 8000ft cross wind.
3 Chlorine leakage from 900 kg Chlorine Concentration upto 30 PPM in
the tonners down-wind direction upto 1247 m
4 Catastrophic failure of 12.5 KW/m heat radiation level at a
Naphtha storage Tank 10000 KL distance of 56.35m
Burnpool radius : 150ft, Flame height:210ft,
Fatality radius upto distance 300ft, First
degree/Injury Zone radius upto
5 10000KL Naphtha tank First degree burn upto 300 ft.
outlet line failure (100%) Fatality radius upto 210ft
Burnpool radius: 100ft
6 Catastrophic failure of 7000KL 12.5 KW/m heat radiation level at a
Naphtha storage Tanks distance of 46.53m
7 Catastrophic failure of 1000 KL 12.5 KW/m heat radiation level at a
Fuel Oil Storage tank. distance of 43.5m
8 Leakage of synthesis 12.5 KW/m heat radiation due to flash fire
gas from loop extends up to 224.3 m
12.5 KW/m radiation level due to jet flame
occur till 92.87 m
The over pressure of 0.2068 bar g is up to a
distance of 265.6m This over pressure may
result in extensive damage.
Note: 1. The IDLH of ammonia has been taken as 500ppm (NIOSH)
2.The IDLH of chlorine has been taken as 30 ppm. (NIOSH)
3. The weather is taken as 5 m/s D pasquill
Synthesis gas (which is hydrogen rich) is produced in the plant for conversion to Ammonia. There is
no hydrogen gas holder for storage. Due to high pressure sufficient quantity is present in the
process vessels and pipings to pose fire / explosion hazard. No off-site effect is envisaged for any
synthesis gas fire explosion accidents.
In case of release of toxic gas into the atmosphere the metrological factors play an important role
in transport, dispersion and diffusion in the atmosphere. The metrological data collected for the
IFFCO Aonla site was utilized for the purpose.
The mean annual speed is 3.5 km/hr. As regards the temperature in peak winter the mean daily
maximum temperature is around 18 degree C and minimum temperature is about 2 °C. In peak
summer the mean daily maximum temperature is about 31. °C and minimum temperature is 14 °C.
Fire hazard is generally experienced in the vessels where a large quantity of flammable material is
stored or when a major leak occurs. Fire hazard is a distinct possibility in Naphtha, FO and Diesel
storage tanks. The major fire risk rests on the storage tank having the maximum storage capacity
i.e. Naphtha storage tank having a capacity of 10000 KL+6000KL+6000KL but normal storage is to
the extent of 7000 KL. In case of catastrophic failure of the tank and the leakage catching fire, the
critical radiation level of 12.5 KW/m will be felt at a distance of 56.35 m and the farthest distance
of flash fire at 229 m. If there is an explosion of the leaking naphtha vapour, over pressure of
0.2068 bar will extend up to 212.1 m. Since there is boundary wall, the effect of over pressure may
not be felt out side the factory premises. At the same time no population is residing in 800m radius
from tank area. The effects of explosion inside the factory premises may result in damage to
equipment. The 12.5 KW/m radiation level resulting from pool fire of Fuel Oil may extend up to
The flow of gas in the synthesis loop is 685000m /hr, which corresponds to 39565 m /hr of
hydrogen. The synthesis loop is at a pressure of 200 Kg/cm g. Assuming escape of the entire
quantity of gas through a 50mm hole and the escaping gas results in a jet flame with 12.5 KW/m
radiation level up to 92.87 m. The farthest extent of flash fire may affect up to 224.3 m. Over
pressure of 0.2068 bar due to explosion will be felt up to a distance of 265.6 m. As mentioned
above, the effects of over pressure may not be felt out side the factory premises.
Due to catastrophic rupture of ammonia storage tank, assuming the entire quantity of 4000
MTdisperses, the IDLH level of ammonia of 750 ppm at 1.35 m/s, D neutral weather conditions is
at a distance of 11000 m from the source of release. Similarly for chlorine release from a tonner
due to valve failure, the IDLH level of chlorine of 30 ppm at 1.35m/s D neutral weather conditions is
at a distance of 500m from the source of release.
ASSESSMENT OF THE EFFECTS OF THE RELEASES (SIZE OF THE AFFECTED
AREA, HEALTH EFFECTS, PROPERTY DAMAGE) :
Assessment of Risk impact is however, more important from the angle of On-site the Emergency
planning as primary concern of such planning is for creating preparedness and providing measures
for tackling major accidents.
Consequence analysis is basically quantitative study of the hazard with the help of internationally
accepted mathematical models, to determine the possible magnitude of damage effects and to
determine the distances up to which the damage may be affected for various failure scenarios.
The consequence analysis results in :
- To aid in better plant layout to reduce hazards.
- For evaluating damage potential for other plants and incorporating protection measures.
- To ascertain damage potential to public and evolve protection measures.
- For preparation of effective planning for both On – Site and off-site emergency.
The results of consequence analysis are useful for getting information about all known and
unknown effects that are of importance when some failure scenario occur and to get information
about how to deal with possible catastrophic events. It also gives the plant authorities, workers and
the public living outside in the vicinity of the plant an understanding of hazard potential and
Bases on the result of consequences analysis, it may be concluded that in most of the cases the
effect would be limited to with-in plant boundary and there is no risk posed to neighborhood
because of this. But for scenarios involving Ammonia Gas leaks the effected zone goes beyond
the factory premises. The risk to the neighborhood of the project is therefore mainly be due to
release of ammonia as described the different scenarios of Ammonia leakage. The probability of
such failure occurrence is extremely low in a order of 3 failure per ten lakh years duration.
It may be also concluded that catastrophic failure of Naphtha Storage Tank, Atmospheric storage
tanks, Let down vessels etc. may occur really and contribute small risk because of low frequency
There are 5000 persons residing in our Township and details of surrounding villages within 5 km
circles and their population is around 10000.
DESCRIPTION OF SAFETY RELEVANT UNITS, AMONG OTHERS SPECIAL DESIGN
Based on Preliminary hazard analysis the design criteria of system elements are as follows –
Ammonia Plant is designed with a great deal of safety. The whole plant is open with proper lay out
of pipe lines, trenches, cables and flame proof lighting arrangements. A proper spacing between
the equipments, reactors, pumps, turbines, and compressors has been kept. Insulation of pipe
lines, vessels have been done wherever required. Proper marking, arrows, colour coding has
been done for convenience and statutory requirements. Control room with emergency doors and
safety equipments are established. Safety trip systems with alarms and trip relays (intrinsically
safe) have been provided to control and safe shut down of the plant during emergencies. Stacks
for furnaces and flare stack for burning of vent / excess gases of 30 M. height have been provided.
Safety valves, Rupture discs, explosion vents, vacuum breakers have been provided as extra
safety precautions other than automatic tripping of concerned equipment / unit in case of any
This plant is safely designed to handle the process with safety valves, Rupture discs and automatic
tripping relays & alarms etc.
All safety measures have been adopted to ensure safe handling and operation of these plants.
Safety devices are of adequate sizes. Waste disposal being done with great care. The stack of
Power Plant is 120 mts. High and analysis of CO2 is being carried out regularly. SPM (Suspended
particulate matter) and SO2 are monitored on weekly basis. All the parameters are always well
with in the prescribed standard of U.P. Pollution control Board / Central Board.
Control and Alarms
Kick back antisurge valves on compressors to avoid surging in compressors.
Pressure controls at different points of the plants to control operating pressure automatically well
within the limits.
Flow controls to control and regulate flow of fluids automatically at desired level.
Temperature controls to control requisite temperature automatically.
Level controls to control level in various equipments automatically.
Likewise several alarms and trip circuits with automatic actuation are given in all the plants for safe
operation and process control.
Safety Relevant Components
The design and operating procedures has been so developed that it enables the safe handling,
operation and upkeep of plants. However, so far no major accident has taken place. The built in
Safety has been the prime factor while selecting the equipments, processes etc. Standards codes
of practices are being followed seriously during the erection, modification etc.
Some Safety relevant components are mentioned below :-
- Use of relief valves, rupture discs, explosion vents of adequate sizes with proper testing.
Checking of these safety relevant components are done in every annual shut down.
- Automatic control valves, solenoid operated quick shut off valves are installed to control any
sort of emergencies.
- Alarms, sensors, relays, trip systems have been provided.
- Proper training, disclosure of information related to Safety rules / procedures have been given.
- Appropriate operating procedures, manuals etc. are implemented since inception.
- Flare stack for burning of vent gases like Ammonia, Natural Gas and Naphtha Vapours have
- All the statutory requirements are being fulfilled and followed.
Setup Of Fire And Safety Section
All staff of Fire & Safety, Health and Environment sections and are of well qualified Engineers,
Fire& safety officers and Doctors.
EQUIPMENTS FOR FIRE FIGHTING
IFFCO-AONLA is well equipped with all fire & Safety appliances like Fire Tenders-3 with a pick up
van, all types of extinguishers like DCP,CO2,WATER CO2 Foam types in adequate numbers,
PPES like Breathing Apparatus of different types & capacities, Online Air masks at various
Hazardous areas ,Gas tight Suits, Alumnised Suits, Explosive meters, Portable Gas Detectors
,Chlorine Emergency Leakage Kit, Air compressor for air cylinders filling, PVC apron & suits, gum
boots, safety shoes, safety belts , Various types of hand gloves ,ladders, nylon life saving net,
Canisters, safety torches, dust pads etc.
Fire Detection/ Alarm System for Plant Control Rooms, Administrative building, Cable Galleries,
Transformers are also provided. These are of Ionization, Optical & Heat sensing type.
All Naphtha tanks are protected by installation of automatic fixed foam pouring system at
their top which is checked periodically and record is maintained.
There is a battery of CO2 cylinders installed for the turbo Generator sets GTG-I , GTG-II &
GT in Ammonia-2, designed to come into operation in case of fire.
In Bagging Plant including Empty bag Storages Fire hydrant system is well laid out &
connected with Smoke detectors have been installed to work in case of any fire.
Smoke detection system is provided at all the important buildings and control rooms.
Well Laid under ground Fire Hydrant System Underground fire hydrant pipes has been
laid throughout the premises as per the TAC guideline, keeping in mind area wise hazard
categorization, based on which the distance of hydrant posts were provided. To maintain
minimum hydrant pressure of 7 kg/cm2 fire pumps & auxiliary systems are provided at fire
pump house near Raw water reservoir.
At various places Eye wash showers have been installed where hazardous chemicals are
Flame Proof fittings at the hydrocarbon storage and handling areas.
Flame arrestors on moving equipments and Spark arrestors on various hazardous fixed
Bounding was done at various flanges to avoid static sparks at the critical hazardous
1. Gas masks for use in leakage of Gases like Ammonia, Chlorine, etc. are available in all the
Plant. Apart from this, breathing apparatus supplied by MSA, (USA) are available in all the
control rooms and at Ammonia storage tank area.
2. Air line systems are provided in Urea and Ammonia control rooms for which air is supplied
from instrument air header. These can be used by the operators working in control room in
case of Ammonia leak.
3. Explosive meters supplied by M/s. MSA, (USA) and RESPO PRODUCTS .are available in
all the plants for checking any leak of gases and testing the vessel and operating areas,
before issue of hot work permit or permit for vessel entry etc.
4. Personnel Protective appliances like safety helmet, safety goggles hand gloves etc., are
issued to all the employees. Apart from this Eye wash showers, face shields, PVC suits
etc. are installed in all sections of the plant.
5. Gas tight suits, chemical splash suits, Fire proximity suits and other suits are available to
handle emergencies like toxic release, fire etc.
6. In order to create sense of safety consciousness safety section organises, various
competitions every year like safety essay, slogan, debate and quiz competitions for regular
employees and safety drawing competition for their children. Prizes are also given to the
winners for motivation.
TRAINING IN FIRE FIGHTING & SAFETY AND OHSAS-18001
1. Training of first aid fire fighting and accident prevention is imparted twice every year to all
the employees, by the officers of fire and safety section. Sufficient numbers of employees
have also been trained by St. John Ambulance Association on „First aid to the injured‟.
2. Twice in a year, Fire and safety section exercised Disaster ON-SITE Mock Drill with
information to all Local authorities, for proper readiness in case of major disaster.
3. Emergency instructions are displayed at required places indicating actions to be taken in
case of any leaks of Ammonia, Chlorine and Naphtha. Hoarding of hidden hazards are
also displayed in different plants along with the control measures to be adopted while
4. Wind socks are provided in Ammonia Plant, Ammonia Storage and handling area, Chorine
handling area and other strategic locations to indicate wind direction in case of any toxic
5. Portable oxygen meters and Explosive meters/Combustible Gas Indicators are also
available in fire and safety section for checking the area or vessel, before entry and job to
be carried out.
6. Periodic medical examination is being done for the employees
7. Proper hygiene and decontamination facilities have been provided and being done
8. By putting the objectives and targets in OHSAS-18001like various trainings on Fire &
Safety ,environment and health matters, periodic health check of the employees, training of
Truck drivers and transporters and Importantly to contract and casual labour. and then
follow up is being done rigorously to meet the objectives
9. All chemicals MSDS (Material Safety Data Sheet) are kept at easily available places to
know about the properties and other values.
10. Each chemical antidotes are also kept available in the hospital and at van
Above : Leakage scenario of Ammonia from sample point.
Conclusion: By effectively identifying the various types of Hazards ,doing the risk analysis and
controlling the risk ,IFFCO-AONLA unit is maintaining the accident free atmosphere for
both the humans and plant/property