Risk Assessment

for Expansion Project of -- Ammonia 2200 MTPD & Urea 3850 MTPD, at Village

Piprola, Distt Shahjahanpur, U.P

Submitted by:

KRIBHCO Shyam Fertilizers Limited

March 2015

Environmental Consultant:

EQMS INDIA PVT. LTD. INDIA

304-305, 3rd Floor, Plot No. 16, Rishabh Corporate Tower,

Community Centre, Karkardooma, Delhi – 110092

Phone: 011-30003200, 30003219; Fax: 011-22374775

Website: www.eqmsindia.com; Email: eqms@eqmsindia.org

HAZARD EVALUATION AND RISK ANALYSIS

1.1. Prelude

Industrial plants deal with materials, which are generally hazardous in nature by virtue of their

intrinsic chemical properties or their operating temperatures or pressures or a combination of

these. Fire, explosion, toxic release or combinations of these are the hazards associated with

industrial plants using hazardous chemicals. More comprehensive, systematic and sophisticated

methods of Safety Engineering, such as, Hazard Analysis and Risk Assessment have now been

developed to improve upon the integrity, reliability and safety of industrial plants.

The primary emphasis in safety engineering is to reduce risk to human life, property and

environment. Some of the more important methods used to achieve this are:

Risk Analysis: Provides a relative measure of the likelihood and severity of various possible

hazardous events by critically examining the plant process and design.

Work Safety Analysis: The technique discerns whether the plant layout and operating

procedures in practice have any inherent infirmities.

Safety Audit: Takes a careful look at plant operating conditions, work practices and work

environments to detect unsafe conditions.

Together, these three broad tools attempt to minimize the chances of accidents occurring. Yet,

there always exists, no matter how remote, probability of occurrence of a major accident. If the

accident involves highly hazardous chemicals in sufficiently large quantities, the consequences

may be serious to the plant, to surrounding areas and the populations residing therein.

To meet emergencies caused by such major accidents, planning response strategies are termed

as On-site Emergency Plan /Disaster Management Plan (DMP).

DMP cannot be considered in isolation or act as a substitute for maintaining good safety

standards in a plant. The best way to protect against a major accident occurrence is by

maintaining very high levels of safety standards.

1.2. Hazards Survey

Hazard identification and risk assessment studies can be performed at any stage, that is, at

initial design stage or as on-going operation in the system. Hazard survey is a formal

systematized approach employed for hazard identification.

Appraisal of material characteristics from Material Safety Data Sheet for various materials and

chemicals used or produced in the fertilizer plant of Kribhco Shyam Fertilizer Limited (KSFL)

indicates that some of the materials are highly inflammable/explosive (Natural Gas/Naphtha) and

some are toxic (Ammonia / Chlorine etc.). In addition some of the intermediate materials

produced in the process (hydrogen and carbon monoxide) are extremely dangerous considering

the process conditions.

All process materials which are capable of producing accidents/hazards owing to their physical

and chemical properties are identified and on the basis of material movement, hold ups are

calculated. Quantities in the pipelines are also taken in to account. Large and sub-sequential

inventories in storage or process are indicative of the potential hazards to the plant and its

surroundings. Flammability and toxicity factors of these inventories can lead to the unpredictable

incidents.

KSFL is producing urea for agriculture use. The major raw materials and other consumable used

are given in Table 6.1. Most of the materials consumed (except Naphtha, Ammonia, Chlorine)

are non-hazardous in nature. However, the materials in the process i.e. NG, hydrogen, carbon

monoxide and ammonia are highly hazardous. The consequence of hazards is enhanced

considering the process conditions (high temperature and pressure). These materials need to be

handled very carefully to ensure safety.

Table 1.1 : Hazardous Materials Storages

SN Hazardous Chemicals

Handled

Quantity Handled /In

Process

Type of Storage

1 Naphtha 3 [4600;1350;600] KL MS Tanks (Main tanks 4600

KL & 1350 KL are having

floating roof while day tank -

600KL has fixed roof tank

with N2 blanketing)

2 Main Raw Material-

Natural Gas

--- Supply from GAIL through

HBJ gas line

3 Ammonia 2X 5000 MT Double walled, double

integrity Atmospheric Tanks

(0ne existing and in

proposed expansion

project).

4 Chlorine Gas 0.9X12 MT Tonnage Cylinders

5 Sulphuric Acid 2 MS Storage Tank

[35;30.5] MT

6 Hydrochloric acid 3

[60;60;60] MT

MSRL Storage Tank

7 Caustic Lye (Sodium

Hydroxide)

2

[44;44] MT

MSRL Storage Tank

8 Diesel 3

[12;12;12] KL

MS Storage Tank

9 Liquid Nitrogen 2

[25;25] KL

Double Wall Storage Tank

1.3. Hazard Evaluation

The evaluation phase determines the extent and degree of employee’s exposure to toxicants

and other physical hazards in the work place environment. In the case of major

accident/breakdown occurrences, hazards exposure may cross plant boundary limit and

persons/properties in the neighbouring areas may be exposed. During the evaluation study, the

likelihood of large and small leaks is also considered. Hazardous substances may be released

as a result of leaks or catastrophic failures causing possible damage to the surrounding areas.

The extent of damage will depend upon the nature of release. The release of flammable and

toxic materials and subsequent ignition results in heat radiation, pressure wave or vapour cloud

depending upon the flammability, toxicity and its physical state.

Sudden exposure to high concentrations of toxic chemicals via leaks or operational upsets (relief

valve pop up) may lead to acute effects, such as, unconsciousness, burning eyes, fits of

coughing, etc.

Chronic effect, however, arises by repeated exposure to toxic chemical concentrations mostly by

small leak. Many fine toxic dusts or vapors are invisible, colourless and odourless (CO). Small

leaks of these substances might not become obvious for months or even years.

1.4. Potential Hazards

Accidental release of flammable or toxic vapours can result in severe consequences. Delayed

ignition of flammable vapours can result in blast overpressures covering large areas. This may

lead to extensive loss of life and property. Toxic clouds may cover yet larger distances due to

lower threshold values in relation to those in case of explosive clouds (the lower explosive

limits).In contrast fires have localized consequences. Fires can be put out or contained in most

cases; there are few mitigating actions one can take once vapour clouds get released.

Therefore, major accident hazards occur upon release of flammable or toxic vapours or BLEVE

in case of pressurized flammable liquefied gases.

1.4.1. Toxic Release

In KSFL complex toxic hazards are mainly due to Ammonia (produced and stored in large

quantity) and chlorine.

Ammonia is a colourless with extremely pungent odour toxic and explosive gas (BP – 33.4C).

Ammonia is highly soluble in water (which can to an extent save an individual from its hazards).

Ammonia exposure limits are –TWA – IND 25 ppm; TWA – ACGIH 25 ppm; STEL- ACGIH 35

ppm. Ammonia is severe irritant respiratory tract. Some hazards arise due to production,

transfer, storage, handling and processing of liquefied ammonia. In case of fully refrigerated

liquid ammonia release, instantaneous flash due to adiabatic expansion is negligibly small.

Evaporation due to aerosol formation also does not occur. Release of liquid ammonia at

pressure (in ammonia plant synthesis section), gives rise to flash evaporation equivalent of the

initial flash due to adiabatic expansion. In case of HP ammonia stored at near ambient

temperature liquid released would completely vaporize with no pool formation. Ejection of high

pressure ammonia appears to entrain 10 to 15 times of its own weight of air enough to

evaporate nearly all the liquid. Thus if an HP release occurs unimpeded the ammonia entrains

sufficient air to evaporate all the droplets carried out with flash.

Chlorine is a toxic gas (B. P. is -34oC). In liquefied form chlorine is a clear amber dense liquid.

The gas is greenish-yellow, about 2.5 times as dense as air, and non-flammable. Liquid chlorine

causes severe irritation and blistering of skin. The gas has a pungent suffocating odour and is

irritant to the nose and throat. It is an extremely powerful vesicant and respiratory irritant.

Typically, exposure to chlorine concentrations of 3 - 6 ppm results in a stinging and burning

sensation in the eyes. Exposures for 0.5 -1 hour to concentrations of 14 - 21 ppm cause

pulmonary oedema, pneumonitis emphysema and bronchitis. This is usually associated with

marked bronchospasm, muscular soreness and headache. Whilst there is inevitably a variation

in individual susceptibility, typically 4 ppm is the maximum concentration that can be breathed

for one hour without any damage, 40-60 ppm is dangerous for a 30-minute exposure and a

concentration of 1000 ppm is likely to be fatal after a few breaths. IDLH (immediately Dangerous

to Life and Health) value for chlorine is 30 ppm. Permissible limit in exposure of chlorine in work

environment under Factories Act, 1948 is 1 ppm Time Weighted Average (TWA) Concentration

(8 hours).

1.4.2. Flammable Release

The flammable materials used at KSFL, involve natural gas used as feedstock, fuel gas and

synthesis gas produced in ammonia plant upstream of Synthesis converter, and naphtha. In

certain section of the plant the operating temperature itself exceeds the auto-ignition

temperature of hydrogen and carbon monoxide. In all such cases due to immediate ignition, a jet

flame will result.

1.4.3. Jet Release

Generally when a gas flows out of an opening at high velocity a turbulent free jet invariably

results. The out-flowing gas entrains a large quantity of the ambient air. The net results being the

jet getting diluted to LEL within the short distance from the release point. If ignited the jet flame

results, but if the released material does not get ignited immediately then the possibility of

vapour cloud explosion or delayed ignition is very remote because by this time free jet has lost

its momentum and the mass can begin to disperse due to environmental forces {the

concentration of flammable material has already fallen below the LEL}.

No vapour cloud explosion has therefore been considered. Jet flames due to impingement on

the adjoining important installations can lead to secondary effects (domino effect). In certain

cases the domino effects could lead/ result in loss of containment of ammonia with serious

consequences. The toxic effect of carbon -monoxide has also not been considered since any

such release due to high system operating pressure (and consequent high momentum) will

either get diluted to low concentrations within short distance from the source due to air

entrainment or will get ignited and hence the consequence distance will be rather small.

1.5. Inventory Analysis

Inventory plays an important part in regard to the potential hazard. Larger the inventory of the

vessel or a system, the larger the quantity of potential release. A practice commonly used to

generate an incident list is to consider the potential leaks and major releases from fractures of

pipelines and vessels containing sizable inventories. The potential vapour release (source

strength) depends upon the quantity of liquid release, the property of the materials and the

operating conditions (pressure). These when combined into matrix and vapour source strength

computed for each release case, a ranking should become a credible exercise. Plant inventory

can get discharged to environment due to loss of containment.

From the preliminary risk assessment study carried out for each participating unit, some of the

possible hazards have been identified. The likely accident scenarios considered are given in

Table 6.2:

Table 1.2 : Likely Accident Scenario

S. No. Scenario Vulnerability Zone Remarks

1. Rupture in NG line Area close to leak /

release

Isolate the line / area; Cool /

drench / dilute the source

point to prevent ignition.

2. Hole in Naphtha

line / tank

Area adjoining leak /

tank farm

Isolate the line / area; Cover

the spillage with foam /

reclaim if possible to prevent

ignition.

3. Ammonia line

leakage and

spillage

Surrounding Area Isolate the line / area.

Approach with gas mask /

lifeline. Dissolve in water and

store and treat the water

gradually.

4 Ammonia Tank

Heavy Leakage

Surrounding Area Try to reclaim Ammona in

other Tank./ Approach with

gas mask / lifeline. Dissolve

in water and store and treat

the water gradually.

5. Chlorine Tonner

Leakage

Surrounding Area Isolate the line / area.

Approach with gas mask /

lifeline. Cover the cylinder

with hood, take a vent line

from hood to caustic

scrubber.

The above mentioned hazards scenarios can further aggravate into much more serious incidents

if not intercepted in time. The fire in one tank of tank farm can spread to adjoining tanks and may

result in explosions. The vulnerability zone will be considerably enlarged. The vapors of toxic

fluids/dust if carried away by wind above TLV concentrations may further enlarge the

vulnerability zone. Similarly, toxic fluid spillage and all wastes leaving the live processing zone if

not decontaminated properly can cause serious health hazard to plant personnel and persons in

nearby area.

1.6. Methodology, Approach and Damage Criteria for Risk Assessment

Consequence analysis is that part of risk analysis, which considers individual failure cases, and

the damage caused by the failure cases. It is done to predict the outcome of potentially serious

hazardous accidents to man and material in and around the plant boundary limits. The

advantages of carrying out consequence analysis are given below:

To improve plant layout

To meet statutory requirements

Protection of public in the nearby areas

Disaster management planning

Training tool

The findings of a consequence analysis provide information about hazardous effects resulting

from an accidental scenario. In addition, methods for dealing with possible catastrophic events

are also provided.

1.6.1. Damage Criteria

In order to understand the damages produced by various scenarios, it is appropriate to discuss

the physiological/physical effects of thermal radiation intensities. The thermal radiation due to

tank fire usually results in burn on the human body. Furthermore, inanimate objects like

equipment, piping, cables, etc. may also be affected and also need to be evaluated for

damages. Table 6.3 and Table 6.4, respectively give tolerable intensities of various objects and

desirable escape time for thermal radiation.

Table 1.3 : Effects due to Incident Radiation Intensity

Incident Radiation

kW/m2 Damage Type

0.7 Equivalent to Solar Radiation

1.6 No discomfort on long duration

4.0

Sufficient to cause pain within 20 sec.

Blistering of skin (first degree burn are

likely).

9.5 Pain threshold reached after 8 sec. Second

degree burn after 20 sec.

12.5

Minimum energy required for piloted

ignition of wood, melting of plastic tubing

etc.

Table 1.4 : Thermal Radiation Impact to Human

Exposure

Duration

Radiation Energy

{1% lethality;

kW/m2}

Radiation Energy

for 2nd degree

burns; kW/m2

Radiation

Energy for

1st degree

burns;

kW/m2

10 sec 21.2 16 12.5

30 9.3 7.0 4.0

1.6.2. Selected Failure Cases

Few accidental scenarios have been considered and subjected to consequence analysis /

damage zone.

1.6.2.1 Rupture in NG Line

NG consisting of 98 % methane is the main raw material (Balance higher hydro carbons and

other gases) and is used to generate hydrogen to fix atmospheric nitrogen as ammonia. Any

leakage in the pipe line {through flange joint / valve/ instrumentation fittings/ welding failure}

would result in hazardous situation. NG will be released at pressure (+ 30 kg/cm2) and also at

high temperature (depending upon the leakage point in the process).

Ambient Temperature : 350 C

Leak source size : ~ 50 mm

Burning Rate : 577 kg / min.

Incident : Flash fire

Figure 1.1 :Rupture in NG Line

Threat Zone:Threat is modelled for the thermal radiation from jet fire. The threat zones identified

are as follows:

Red : 14 meters --- (10.0 kW/(sq m) = potentially lethal within 60 sec)

Orange : 19 meters --- (5.0 kW/(sq m) = 2nd degree burns within 60 sec)

Yellow : 30 meters --- (2.0 kW/(sq m) = pain within 60 sec)

1.6.2.2 Hole in Naphtha Line/ Tank

Naphtha is used only incase NG shortage from GAIL. The two large and one small day naphtha

storage tanksand transfer lines are the likely sources of leakages. The leaked naphtha will form

a pool and incase of the naphtha catching fire, the radiation intensity / thermal load on the

adjoining area / material has been assessed as below.

Ambient Temperature : 30C Leaked Naphtha Pool Diameter : 20 m

Intensity of Radiation : 71.6 kW / m2

Thermal Load

kW/m2

Distance from edge of the pool

(m)

Remarks

25.8 1

17.0 4

9.0 10

4.0 21 1st degree burn

2.0 31

1.1 40

1.6.2.3 Failure of Ammonia Line

Liquid ammonia is the main raw material for urea plant. In addition to process hold up in

ammonia and urea plant, there is one large ammonia atmospheric storage tank of capacity-

5,000 mt. Ammonia has got odour and any leakage can be immediately noticed and calls for an

action taken.

Ambient Temperature : 35C Ammonia IDLH : 300 ppm STEL Value : 30 ppm or 24.3 mg/m3 Source Strength:

o Puddle Diameter : 20 m

o Puddle Volume : 100 m3

o Total Ammount Released : 10,531 kg

o Release Duration : 60 min

Threat Zone:Threat is modelled as Gaussian Model. The threat zones identified are as follows:

Red: 1.1 km --- (300 ppm = IDLH) Orange: 1.6 km --- (150 ppm = ERPG – 2) Yellow: 4.4 km --- (25 ppm = ERPG – 1)

Figure 1.2 Failure in Ammonia Line

1.6.2.4 Ammonia Tank Failure

Heavy Ammonia Leakage – Puddle Volume 4000 m3. Ammonia evaporates and spreads all

around. Try to reclaim Ammonia to other tank. Ammonia has got odour and any leakage can be

immediately noticed and calls for an action taken.

Ambient Temperature :15C Stability Class- “F” Ammonia IDLH : 300 ppm STEL Value : 30 ppm or 24.3 mg/m3 Source Strength:

o Puddle Volume : 4000 m3

Threat Zone: Threat is modelled as Gaussian Model. The threat zones identified are as follows:

Red : 1.3 kilometers --- (1100 ppm = AEGL-3 (60 min))

Orange: 3.1 kilometers --- (300 ppm = IDLH)

Yellow: 4.9 kilometers --- (160 ppm = AEGL-2 (60 min))

Figure 1.3 Ammonia Tank Heavy Leakage Stability Class “F”

Ambient Temperature :35C Stability Class- “D” Ammonia IDLH : 300 ppm STEL Value : 30 ppm or 24.3 mg/m3 Source Strength:

o Puddle Volume : 4000 m3

Threat Zone: Threat is modelled as Gaussian Model. The threat zones identified are as follows:

Red : 440 meters --- (1100 ppm = AEGL-3 (60 min))

Orange: 939 meters --- (300 ppm = IDLH)

Yellow: 1.4 kilometers --- (160 ppm = AEGL-2 (60 min))

Figure 1.4 Ammonia Tank Heavy Leakage Stability Class “D”

1.6.2.5 Chlorine Cylinder Leakage

Chlorine is used as biocides in cooling water system and water purification Chlorine is highly toxic (IDLH – 10 ppm). Any leakages in the system will cause toxic release which will spread in down wind direction. The dispersion due to I cm (dia) leakages are considered for modelling as below:

Ambient Temperature : 35C Chlorine IDLH Value : 10 ppm Source Strength : ~ 2 kg/ min Release Duration : 60 min

Threat Zone: Threat is modelled with heavy gas model. The threat zones identified are as follows:

Red : 157 m --- (20 ppm = AEGL*-3 (60 min)1 Orange : 226 m --- (10 ppm = IDLH) Yellow : 526 m --- (2 ppm = AEGL-2 (60 min))

1AEGL – Acute Exposure Guideline Level

Figure 1.5 Chlorine Cylinder Leakage

1.7. General Control Measures

Since some of the substances in use at KSFL are hazardous with severe fire and explosion potential and also toxic in nature, it is necessary to use appropriate control measures recommended for such substances:

1.7.1. Flammable Gas Fires

Fire control generally consists of directing, diluting and dispersing the inflammable gas/vapor to prevent contact with persons, to prevent it from infiltrating structures if the leak is out door, and to avoid its contact with ignition sources while, if possible, simultaneously stopping the flow of gas. NG is lighter than air it will go up in the atmosphere once its momentum due to pressure gets dissipated. Gas direction, dilution and dispersion require the use of a carrier fluid, and air, water and steam have proven to be practical carriers. Water in the form of spray, applied from hoses or monitor nozzles or by fixed water spray system may act as a good carrier fluid for inflammable vapors/gases.

1.7.2. Protection against BLEVE

A basic BLEVE safeguard is to reduce the chance of the thermal (fire) exposure to the container. During a fire exposure the application of water is a basic safeguard to prevent a BLEVE or a compressed gas container failure. Automatic sprinkler protection can greatly limit pressure rise from heat and high metal temperatures from fire exposures.

All pressure vessels and tanks should be periodically inspected for leakage from vessels and its appurtenances. Gas detection instruments/ acoustic gas leak detectors are invaluable help in detecting the leakages.

Over pressure protection devices, namely, relief valves, rupture discs, alarms, etc. are to be regularly checked and calibrated if required.

1.7.3. Commonly Recommended Control Measures

A number of preventive control measures for hazardous occurrences have been analyzed and discussed above. Some more salient points are enumerated below:

All storage tanks in the tank farm should be dyked and those storing volatile material may be provided with non-combustible insulation within aluminums protection jacket. The tanks should have water deluge system.

Ammonia has got odour. Always look for wind direction while moving in ammonia prone area. Move / approach across or up wind direction. Ammonia is highly soluble in water. A wet handkerchief / cloth are helpful in such a case. While planning a job in such area keep breathing apparatus / gas mask/ water hose ready for emergency.

Concentration detectors for hazardous chemical vapors fire Smoke / heat detectors and fire alarm should be installed at all strategic locations in the plant.

A schedule for preventive maintenance including health survey of all plant equipment should be adhered to as far as possible.

Ensure the absence of ignition sources in Naphtha / HSD / Ammonia storage area. Ensure placement of fire fighting facilities, such as, carbon dioxide, dry chemical powder and

foam type fire extinguishers in addition to fire hydrant system, at strategic locations. Spill control measures, such as, removal of all ignition sources from the spill area and ventilating the area as well as soaking the spilled material with paper, towel or mud and letting the volatile substance evaporate slowly in a safe area.

Compulsory use of protective clothing, non-sparking tools and warning signs during critical operations and maintenance.

Training / refresher courses on safety information’s / norms. Eyewash and showers should be put up at strategic places for use during emergencies.

A group of plant personnel should be trained in first aid, rescue, fire fighting and emergency control measures. These personnel will form core group/emergency squad who will fight the emergency and also act as rescue and first aid team.

In order to ensure communication from isolated places/locations Walkie-Talkie be made available to persons working in these areas. This will considerably improve the effectiveness of emergency management.

There is no substitute for training-mock drills and these must be held at regular interval keeping the following objectives in mind:

Real time mock-drill should be carried out for probable/likely hazardous situation. Target to be set up for various tasks and events during an emergency.

Weak links should be marked and corrective action taken to improve effectiveness during emergency.

KSFL has already implemented many of the measures.