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RRA Study of Refinery Expansion Project,

HPCL Mumbai Refinery

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Template No. 5-0000-0001-T2 Rev. 1 Copyrights EIL ¬ All rights reserved

PREFACE

M/s HPCL intends to increase the refining capacity of its Mumbai refinery upto 9.5 MMTPA from

current 7.5 MMTPA. Engineers India Limited (EIL), New Delhi has been appointed by M/s HPCL,

Mumbai Refinery as a Consultant for EIA & RRA of this Project.

In this perspective, Rapid Risk Analysis Study of the units under scope of Refinery Expansion

Project is being carried out.

Rapid Risk Analysis study identifies the hazards associated with the facility, analyses the

consequences, draws suitable conclusions and provides necessary recommendations to mitigate

the hazard/ risk.

This Rapid Risk Analysis study is based on the information made available at the time of this

study and EIL’s own data source for similar plants. EIL has exercised all reasonable skill, care

and diligence in carrying out the study. However, this report is not deemed to be any undertaking,

warrantee or certificate.



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TABLE OF CONTENTS

1 EXECUTIVE SUMMARY ......................................................................................................................... 6

1.1 INTRODUCTION .............................................................................................................................. 6

1.2 APPROACH METHODOLOGY ........................................................................................................ 6

1.3 MAJOR OBSERVATIONS & RECOMMENDATIONS ..................................................................... 6

2 INTRODCUTION ...................................................................................................................................... 9

2.1 STUDY AIMS AND OBJECTIVE ...................................................................................................... 9

2.2 SCOPE OF WORK .......................................................................................................................... 9

3 SITE CONDITION .................................................................................................................................. 11

3.1 GENERAL ...................................................................................................................................... 11

3.2 SITE, LOCATION AND VICINITY .................................................................................................. 11

3.3 METEOROLOGICAL CONDITIONS .............................................................................................. 11

4 HAZARDS ASSOCIATED WITH THE FACILITIES ............................................................................... 15

4.1 GENERAL ...................................................................................................................................... 15

4.2 HAZARDS ASSOCIATED WITH FLAMMABLE MATERIALS ....................................................... 15

4.2.1 LIQUIFIED PETROLEUM GAS .............................................................................................. 15

4.2.2 HYDROGEN ........................................................................................................................... 15

4.2.3 NAPHTHA AND OTHER HEAVIER HYDROCARBONS ....................................................... 16

4.3 HAZARDS ASSOCIATED WITH TOXIC MATERIALS .................................................................. 17

4.3.1 HYDROGEN SULPHIDE ....................................................................................................... 17

4.3.2 AMMONIA .............................................................................................................................. 17

4.3.3 BENZENE .............................................................................................................................. 17

4.3.4 TOLUENE .............................................................................................................................. 18

5 HAZARD IDENTIFICATION ................................................................................................................... 20

5.1 GENERAL ...................................................................................................................................... 20

5.2 MODES OF FAILURE .................................................................................................................... 20

5.3 SELECTED FAILURE CASES ....................................................................................................... 21

6 CONSEQUENCE ANALYSIS ................................................................................................................ 23

6.1 GENERAL ...................................................................................................................................... 23

6.2 CONSEQUENCE ANALYSIS MODELLING .................................................................................. 23

6.2.1 DISCHARGE RATE ............................................................................................................... 23

6.2.2 DISPERSION ......................................................................................................................... 23



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6.2.3 FLASH FIRE ........................................................................................................................... 23

6.2.4 JET FIRE ................................................................................................................................ 24

6.2.5 POOL FIRE ............................................................................................................................ 24

6.2.6 VAPOR CLOUD EXPLOSION ............................................................................................... 24

6.2.7 TOXIC RELEASE ................................................................................................................... 24

6.3 SIZE AND DURATION OF RELEASE ........................................................................................... 24

6.4 DAMAGE CRITERIA ...................................................................................................................... 25

6.4.1 LFL OR FLASH FIRE ............................................................................................................. 25

6.4.2 THERMAL HAZARD DUE TO POOL FIRE, JET FIRE AND FIRE BALL .............................. 25

6.4.3 VAPOR CLOUD EXPLOSION ............................................................................................... 26

6.4.4 TOXIC HAZARD ..................................................................................................................... 26

6.5 CONSEQUENCE ANALYSIS FOR EXISTING UNITS UNDERGOING REVAMP/ MODIFICATIONS ....................................................................................................................................... 26

6.5.1 APS ........................................................................................................................................ 27

6.5.2 NHT/CCR ............................................................................................................................... 30

6.5.3 PRIME G ................................................................................................................................ 32

6.5.4 NHDT/ISOM ........................................................................................................................... 35

6.5.5 DHT ........................................................................................................................................ 38

6.6 CONSEQUENCE ANALYSIS FOR NEW PROPOSED UNITS ..................................................... 41

6.6.1 HGU ....................................................................................................................................... 41

6.6.2 VBU ........................................................................................................................................ 42

6.6.3 VPS ........................................................................................................................................ 43

6.6.4 OFFSITES .............................................................................................................................. 44

6.6.5 PRU ........................................................................................................................................ 46

7 DETAILED ANALYSIS & RECOMMENDATIONS ................................................................................. 49

8 GLOSSARY............................................................................................................................................ 57

9 REFERENCES ....................................................................................................................................... 59

ANNEXURE-I: CONSEQUENCE ANALYSIS HAZARD DISTANCES (EXISTING & PROPOSED UNITS)

ANNEXURE-II: FIGURES FOR CONSEQUENCE ANALYSIS OF EXISTING UNITS

ANNEXURE-III: FIGURES FOR CONSEQUENCE ANALYSIS OF NEW PROPOSED UNITS



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LIST OF TABLES

Table 1: New Proposed Process Facilities under Refinery Expansion Project ............................................... 9

Table 2: Existing Process Facilities undergoing revamp (modifications) under Refinery Expansion Project .. 9

Table 3: Offsite facilities –Storage tanks ........................................................................................................ 10

Table 4: Atmospheric Parameter ................................................................................................................... 12

Table 5: Average Mean Wind Speed (m/s) .................................................................................................... 12

Table 6: % Number of Days Wind From ........................................................................................................ 12

Table 7: Pasquill Stability Classes ................................................................................................................. 13

Table 8: Weather Conditions ......................................................................................................................... 14

Table 9: Hazardous Properties of LPG .......................................................................................................... 15

Table 10: Hazardous Properties of Hydrogen................................................................................................ 16

Table 11: Hazardous Properties of Naphtha .................................................................................................. 16

Table 12: Toxic Effects of Hydrogen Sulphide ............................................................................................... 17

Table 13: Toxic Effects of Ammonia .............................................................................................................. 17

Table 14: Hazardous Properties of Benzene ................................................................................................. 18

Table 15: Toxic effects of Benzene ................................................................................................................ 18

Table 16: Hazardous Properties of Toluene .................................................................................................. 19

Table 17: Toxic effects of Toluene ................................................................................................................. 19

Table 18: Size of Release .............................................................................................................................. 24

Table 19: Damage Due to Incident Thermal Radiation Intensity ................................................................... 25

Table 20: Damage Effects of Blast Overpressure ......................................................................................... 26

LIST OF FIGURES

Figure 1: HPCL Mumbai Refinery Site ........................................................................................................... 11



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1 EXECUTIVE SUMMARY 1.1 INTRODUCTION HPCL intends to increase the refining capacity of its Mumbai refinery up to 9.5 MMTPA from

current 7.5 MMTPA. The desired capacity increase is proposed to be achieved by implementation

of the expansion project as below:

Revamp of FRAPS upto 6 MMTPA crude throughput

Post expansion, the existing FRVPS and LRVPS units shall be dismantled. A new VPS

unit (VDU) shall be installed for processing the RCO generated from FRAPS

Revamp of 20% shall be done in the MS block units (NHDT/ISOM, NHT/CCR and Prime-

G) in order to accommodate the increased light distillates.

Modifications in DHDT for Hydrotreating VGO

A new HGU unit, in order to meet the peak requirement of hydrogen during VGO

Hydrotreating in DHDT.

A new Visbreaker unit, as an option of residue upgradation

A new PRU, with 2 nos. mounded bullets (Change of service of existing LPG mounded

bullets) & associated pumping system

Propylene Gantry

GTG + HRSG + BPSTG with RLNG & Naphtha as fuel.

In this context Rapid Risk Analysis Study of the above mentioned units under scope of Refinery

Expansion Project is being carried out.

1.2 APPROACH METHODOLOGY RRA study evaluates the consequences of potential failure scenarios, assess extent of damages,

based on damage criteria’s and suggest suitable measures for mitigating the Hazard.

RRA involves identification of various potential hazards & credible failure scenarios for various

units and other facilities including off-site storages & pumping, etc., based on their frequency of

occurrence & resulting consequence. Basically two types of scenarios are identified spanning

across various process facilities; Cases with high chance of occurrence but having low

consequence, e.g., Instrument Tapping Failure and cases with low chance of occurrence but

having high consequence, e.g., Catastrophic Rupture of Pressure Vessels / Large Hole on the

outlet of Pressure Vessels. Effect zones for various outcomes of failure scenarios (Flash Fire, Jet

Fire, Pool Fire, Blast overpressure, toxic release, etc.) are studied and identified in terms of

distances on plot plan. Based on effect zones, measures for mitigation of the hazard/risk are

suggested.

1.3 MAJOR OBSERVATIONS & RECOMMENDATIONS The major credible failure scenarios are modeled in terms of hydrocarbon release rate,

dispersion, flammability & toxic characteristics and detailed consequence analysis of the outcome

is presented in the Rapid Risk Analysis (RRA) report. The summary of major observations &



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recommendations of RRA study for new proposed process units & existing process units

undergoing revamp (modifications) under Refinery Expansion Project are summarized below.

Refer Section - 7 for detailed analysis and recommendations.

APS operator cabin is under affect zone of 5 & 3 psi blast overpressure waves of high frequency

credible failure scenarios in APS unit. The operator cabin personnel needs to be shifted to safe

location or to be accommodated within blast resistant DIDC control room.

Depending upon the prevalent weather conditions at the time of release, Administrative building &

its Annex buildings and Workshop may get affected by explosion & toxic outcomes in the event of

realization of high frequency credible failure scenarios in NHT/CCR. It is recommended to ensure

hydrocarbon & toxic gas detectors at appropriate locations within the unit and detailed mitigating

procedures are available as a part of the Disaster Management Plan (DMP) & Emergency

response procedures (ERP).

Fire tender bays and store of Fire & Safety Building are under direct affect zone of the high

frequency credible failure scenarios of NHDT/ISOM unit. It is recommended to relocate the fire

tender bays to a safe place. Also, it is recommended to add an auxiliary fire station at safe

location, to cater post expansion fire & safety requirements.

In the event of high frequency failure scenario in DHT unit (instrument tapping failure at Charge

Pumps) storage tank TK-111 located on east side of the unit may get affected by the 5 psi blast

overpressure wave, depending upon the prevalent weather condition and presence of ignition

source at the time of release. It is recommended to minimize the traffic on road between DHT and

dyke containing Tanks (TK-110/111/112/113) and ensure adequate number of hydrocarbon

detectors are placed at suitable locations within the unit for early leak detection and inventory

isolation.

New Proposed HGU is surrounded by Class-A storage tanks from three sides. In the event of

realization of credible high frequency failure scenario in Naphtha/LPG handling section, storage

tanks in adjacent dykes may get affected and lead to possible domino effects. It is recommended

to locate Naphtha & LPG handling section of the HGU towards northern side (DHT side) in the

proposed plot. However, affected tankage/s if any, needs to be either relocated or the service of

the tanks needs to be changed to Class-C/B service, to downscale the hazard.

Explosion & radiation effects for credible high frequency failure scenarios for the Fractionator

overhead & stabilizer section of VBU are modelled & it is observed that affect zone shall extend

beyond the unit’s B/L and may affect the storage tanks in nearby dykes. It is recommended to

locate Fractionator overhead & stabilizer section of the VBU towards eastern side in the proposed

plot.

Consequence modelling is carried out for credible failure scenarios of PRU. It is observed that

affect zone may extend beyond the unit’s B/L & affect the storage tanks in nearby dyke,



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depending upon the location of the release, ignition source encountered and prevalent weather

conditions at the time of release. It is recommended to locate ethanizer section of PRU preferably

towards northern side of the proposed plot.

The scenario of Diesel Tank on Fire in the Offsite area is modelled and it is observed that 8

Kw/m2 radiation intensity in the event of Pool Fire may affect the nearby Diesel tank/s, leading to

possible failure of tank. Hence, it is recommended to provide necessary active fire protection for

the Diesel tanks and adjacent VGO Feed tanks.

Explosion & radiation effects for credible high frequency failure scenarios for Diesel Feed Pump is

modelled and it is observed that the 8 Kw/m2 Pool Fire radiation intensity and 8 & 32 Kw/m2 Jet

Fire radiation intensity may affect the project ware house. It is recommended to shift the project

ware house from its present location.

Instrument Tapping Failure at Propylene Product Loading Pump in the Offsite is modeled and it is

observed that the 32 & 8 Kw/m2 Jet fire radiation intensity may affect nearby Tank-6 (Diesel back

blending stream tank). Since Tank-6 are in close proximity of Propylene loading pumps, it is

recommended to relocate these tanks to safe location.

Radiation & explosion effect zones in the event of Propylene Loading arm rupture in the

Propylene Loading Gantry may affect existing truck parking & LPG Bottling plant. HT line near

Truck parking area may be a potential source of ignition in event of any leakage in the gantry.

Existing LPG bottling plant & truck parking area in the close proximity of loading gantry are not

advisable from safety perspective. It is recommended not to allow any truck parking beneath HT

wire and also in LFL zone (~ 85 m from the edge of the Propylene Loading Gantry). Also, it is

recommended to provide hydrocarbon detectors near loading arms with hooters & automatic

water sprinkler system. Safe evacuation plan in the event of any leakage in the Propylene Gantry

& LPG bottling plant needs to be developed & shall be included in the emergency response plan.

It is suggested to evaluate the risk to the personnel through quantified risk analysis at the time of

detailed engineering.

Outcomes of the low frequency credible failure scenarios for various units (APS, NHT/CCR,

NHT/ISOM, Prime-G, DHT, HGU, VBU, PRU and VPS) are recommended to be included for

updation of the existing Disaster Management Plan (DMP) & Emergency Response Plan (ERP).

Adequate number of hydrocarbon/ toxic detectors to be ensured at suitable locations within these

units for early leak detection and inventory isolation.



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2 INTRODCUTION 2.1 STUDY AIMS AND OBJECTIVE

The objectives of the Rapid Risk Analysis study are to identify and quantify all potential failure

modes that may lead to hazardous consequences and extent. Typical hazardous consequences

include fire, explosion and toxic releases.

The Rapid Risk analysis will also identify potential hazardous consequences having impacts on

population and property in the vicinity of the facilities, and provides information necessary in

developing strategies to prevent accidents and formulate the Disaster Management Plan.

The Rapid Risk Analysis includes the following steps:

a) Identification of failure cases within the process and off-site facilities

b) Evaluate process hazards emanating from the identified potential accident scenarios.

c) Analyze the damage effects to surroundings due to such incidents.

d) Suggest mitigating measures to reduce the hazard / risk.

The Risk analysis study has been carried out using the risk assessment software program

‘PHAST ver. 7.11 developed by DNV Technica.

2.2 SCOPE OF WORK

The study addresses the hazards that can be realized due to operations associated with the

proposed facilities under Refinery Expansion Project. It covers the following facilities of Refinery:

Table 1: New Proposed Process Facilities under Refinery Expansion Project1

S. No. Description Remarks

1. HGU

2. VBU

3. VPS

4. PRU

5. Propylene Truck Loading Gantry

6. GTG + HRSG + BPSTG with RLNG & Naphtha as fuel.

Table 2: Existing Process Facilities undergoing revamp (modifications) under Refinery Expansion

Project


1. APS

2. NHT/CCR

1 Refer the DFR for unit capacities



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3. Prime G

4. NHDT/ISOM

5. DHT

Table 3: Offsite facilities –Storage tanks

S. No. Facility Remarks

1. Raw Diesel Storage Tanks

2. HGU Feed Tanks

3. VBU Feed Tanks

4. VGO Feed Tanks

5. Hydrotreated VGO Tanks

6. Diesel Back Blending Stream Tank

7. Slop/Off Spec Tanks

8. Propylene Mounded Bullets Change of service of existing LPG

mounded bullets



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3 SITE CONDITION 3.1 GENERAL

This chapter describes the location of HPCL Mumbai Refinery complex and meteorological data,

which have been used for the Rapid Risk Analysis study.

3.2 SITE, LOCATION AND VICINITY

The HPCL Mumbai Refinery is located in Aanik Village, Chembur tehsil and district Chembur in

Mumbai in Maharashtra. The site is located approximately at Latitude 19.01974 and longitude of

72.90321.

Figure 1: HPCL Mumbai Refinery Site

3.3 METEOROLOGICAL CONDITIONS

The consequences of released toxic or flammable material are largely dependent on the

prevailing weather conditions. For the assessment of major scenarios involving release of toxic or

flammable materials, the most important meteorological parameters are those that affect the

atmospheric dispersion of the escaping material. The crucial variables are wind direction, wind

speed, atmospheric stability and temperature. Rainfall does not have any direct bearing on the

results of the risk analysis; however, it can have beneficial effects by absorption / washout of

released materials. Actual behavior of any release would largely depend on prevailing weather

condition at the time of release.



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For the Risk Analysis study, Meteorological data of Mumbai have been taken from the

Climatological Tables of Observatories in India (1961-1990) published by Indian Meteorological

Department, Pune.

Atmospheric Parameters The Climatological data which have been used for the Risk Analysis study is summarized below: Table 4: Atmospheric Parameter

Sl. No. Parameter Average Value Considered For Study

1. Ambient Temperature (OC) 28

2. Atmospheric Pressure (mm Hg) 760

3. Relative Humidity (%) 70

4. Solar Radiation flux (kW/m2) 0.76

Wind Speed and Wind Direction The average monthly wind speed varies between 1.8 to 4.5 m/s. For the purpose of present study

the selected representative wind speeds are 2 m/s, 3 m/s and 5 m/s. These wind speeds have

been selected to represent the entire range of wind speeds in the region. Table 5: Average Mean Wind Speed (m/s)

Jan Feb Mar April May June July Aug Sep Oct Nov Dec

1.89 2.19 2.36 2.64 3.08 3.88 4.47 4 2.44 1.72 1.72 1.75

Table 6: % Number of Days Wind From

N NE E SE S SW W NW Calm

D 9 1 0 0 1 10 30 48 1

N 4 10 14 4 4 8 13 5 38

Weather Category One of the most important characteristics of atmosphere is its stability. Stability of atmosphere is

its tendency to resist vertical motion or to suppress existing turbulence. This tendency directly

influences the ability of atmosphere to disperse pollutants emitted into it from the facilities. In most

dispersion scenarios, the relevant atmospheric layer is that nearest to the ground, varying in

thickness from a few meters to a few thousand meters. Turbulence induced by buoyancy forces in

the atmosphere is closely related to the vertical temperature gradient.

Temperature normally decreases with increasing height in the atmosphere. The rate at which the

temperature of air decreases with height is called Environmental Lapse Rate (ELR). It will vary

from time to time and from place to place. The atmosphere is said to be stable, neutral or unstable



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according to ELR is less than, equal to or greater than Dry Adiabatic Lapse Rate (DALR), which is

a constant value of 0.98°C/100 meters.

Pasquill stability parameter, based on Pasquill – Gifford categorization, is such a meteorological

parameter, which decreases the stability of atmosphere, i.e., the degree of convective turbulence.

Pasquill has defined six stability classes ranging from `A' (extremely unstable) to `F' (stable). Wind

speeds, intensity of solar radiation (daytime insulation) and nighttime sky cover have been

identified as prime factors defining these stability categories. Below Table indicates the various

Pasquill stability classes.

Table 7: Pasquill Stability Classes

Surface Wind Speed

(meter/s)

Day time solar radiation Night time cloud cover

Strong Medium Slight Thin < 3/8 Medium 3/8 Overcast >4/5

< 2 A A – B B - - D

2 – 3 A – B B C E F D

3 – 5 B B – C C D E D

5 – 6 C C – D D D D D

> 6 C D D D D D

Legend: A = Very unstable, B = Unstable, C = Moderately unstable, D = Neutral, E = Moderately

stable, F = stable

When the atmosphere is unstable and wind speeds are moderate or high or gusty, rapid

dispersion of pollutants will occur. Under these conditions, pollutant concentrations in air will be

moderate or low and the material will be dispersed rapidly. When the atmosphere is stable and

wind speed is low, dispersion of material will be limited and pollutant concentration in air will be

high. In general worst dispersion conditions (i.e. contributing to greater hazard distances) occur

during low wind speed and very stable weather conditions, such as that at 1F weather condition

(i.e. 1 m/s wind speed and Pasquill Stability F).

Stability category for the present study is identified based on the cloud amount and wind speed.

For risk analysis the representative average annual weather conditions are assessed based on

the following:

Literature suggests that Category ‘D’ is most probable at coastal sites in moderate climates, and

may occur for up to 80% of the time. Hence, Pasquill stability category best represented for the

present facilities would be category ‘D’ (neutral). Pasquill Stability F has been considered for

accounting the night time weather.

The consequence results are reported in tabular form for all the weather conditions and are

represented graphically for worst weather condition.



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Table 8: Weather Conditions

Wind Speed Pasquill Stability

2 F

3 D

5 D

Note: For RRA Study Plot Plan (Doc. No.: A430-000-17-44-0001 Rev F & 50120-01-FH-00001 Rev 2) has been used.



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4 HAZARDS ASSOCIATED WITH THE FACILITIES 4.1 GENERAL Refinery complex handles a number of hazardous materials like LPG, Hydrogen, Naphtha and

other hydrocarbons which have a potential to cause fire and explosion hazards. The toxic

chemicals like Benzene and Hydrogen sulfide are also handled in the Refinery. This chapter

describes in brief the hazards associated with these materials.

4.2 HAZARDS ASSOCIATED WITH FLAMMABLE MATERIALS 4.2.1 LIQUIFIED PETROLEUM GAS

LPG is a colorless liquefied gas that is heavier than air and may have a foul smelling odorant

added to it. It is a flammable gas and may cause flash fire and delayed ignition.

LPG is incompatible to oxidizing and combustible materials. It is stable at normal temperatures

and pressure. If it is released at temperatures higher than the normal boiling point it can flash

significantly and would lead to high entrainment of gas phase in the liquid phase. High

entrainment of gas phase in the liquid phase can lead to jet fires. On the other hand negligible

flashing i.e. release of LPG at temperatures near boiling points would lead to formation of pools

and then pool fire. LPG releases may also lead to explosion in case of delayed ignition.

Inhalation of LPG vapors by human beings in considerable concentration may affect the central

nervous system and lead to depression. Inhalation of extremely high concentration of LPG may

lead to death due to suffocation from lack of oxygen. Contact with liquefied LPG may cause

frostbite. Refer to below table for properties of LPG. Table 9: Hazardous Properties of LPG

Sl. No. Properties Values

1. LFL (%v/v) 1.7

2. UFL (%v/v) 9.0

3. Auto ignition temperature (°C) 420-540

4. Heat of combustion (Kcal/Kg) 10960

5. Normal Boiling point (°C) -20 to –27

6. Flash point (°C) - 60

4.2.2 HYDROGEN

Hydrogen (H2) is a gas lighter than air at normal temperature and pressure. It is highly flammable

and explosive. It has the widest range of flammable concentrations in air among all common

gaseous fuels. This flammable range of Hydrogen varies from 4% by volume (lower flammable

limit) to 75% by volume (upper flammable limit). Hydrogen flame (or fire) is nearly invisible even

though the flame temperature is higher than that of hydrocarbon fires and hence poses greater

hazards to persons in the vicinity.



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Constant exposure of certain types of ferritic steels to hydrogen results in the embrittlement of the

metals. Leakage can be caused by such embrittlement in pipes, welds, and metal gaskets.

In terms of toxicity, hydrogen is a simple asphyxiant. Exposure to high concentrations may

exclude an adequate supply of oxygen to the lungs. No significant effect to human through dermal

absorption and ingestion is reported. Refer to below table for properties of hydrogen.

Table 10: Hazardous Properties of Hydrogen


1. LFL (%v/v) 4.12

2. UFL (%v/v) 74.2

3. Auto ignition temperature (°C) 500

4. Heat of combustion (Kcal/Kg) 28700

5. Normal Boiling point (°C) -252

6. Flash point (°C) N.A.

4.2.3 NAPHTHA AND OTHER HEAVIER HYDROCARBONS

The major hazards from these types of hydrocarbons are fire and radiation. Any spillage or loss of

containment of heavier hydrocarbons may create a highly flammable pool of liquid around the

source of release.

If it is released at temperatures higher than the normal boiling point it can flash significantly and

would lead to high entrainment of gas phase in the liquid phase. High entrainment of gas phase in

the liquid phase can lead to jet fires. On the other hand negligible flashing i.e. release at

temperatures near boiling points would lead to formation of pools and then pool fire.

Spillage of comparatively lighter hydrocarbons like Naphtha may result in formation of vapor

cloud. Flash fire/ explosion can occur in case of ignition. Refer to below table for properties of

Naphtha.

Table 11: Hazardous Properties of Naphtha

S. No. Properties Values

1. LFL (%v/v) 0.8

2. UFL (%v/v) 5.0


4. Heat of combustion (Kcal//Kg) 10,100

5. Normal Boiling point (°C) 130 -155

6. Flash point (°C) 38 - 42



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4.3 HAZARDS ASSOCIATED WITH TOXIC MATERIALS 4.3.1 HYDROGEN SULPHIDE

Hydrogen sulfide is a known toxic gas and has harmful physiological effects. Accidental release of

hydrocarbons containing hydrogen sulfide poses toxic hazards to exposed population. Refer to

below table for hazardous properties of Hydrogen Sulphide. Table 12: Toxic Effects of Hydrogen Sulphide

Sl. No. Threshold Limits Concentration (PPM)

1. Odor threshold 0.0047

2. Threshold Limit Value(TLV) 10

3. Short Term Exposure Limit (STEL)(15 Minutes) 15

4. Immediately Dangerous to Life and Health (IDLH) level (for 30

min exposure) 100

4.3.2 AMMONIA

Ammonia is likely to be present in sour gas produced from Sour water stripper unit (SWSU). The

hazard associated with ammonia is both toxic and flammable hazards. Toxic hazards being more

pronounced. Vapors of ammonia may cause severe eye or throat irritation and permanent injury

may result. Contact with the liquid freezes skin and produces a caustic burn. Below table indicates

the toxic properties of ammonia.

Table 13: Toxic Effects of Ammonia


1. Threshold Limit Value (TLV) 25

2. Short Term Exposure Limit (STEL)(15 Minutes) 35

3. Immediately Dangerous to Life and Health (IDLH) level

(for 30 min exposure) 300

4.3.3 BENZENE

The hazards associated with benzene are both toxic and flammable hazards. Benzene has a very

low flash point (-11.1°C), indicating that its vapor cloud easily gets ignited. The vapor which is

about to 3 times heavier than air may originate flash fire and explosions.

If it is released at temperatures higher than the normal boiling point it can flash significantly and

would lead to high entrainment of gas phase in the liquid phase. High entrainment of gas phase in

the liquid phase can lead to jet fires. On the other hand negligible flashing i.e. release of Benzene

at temperatures near boiling points would lead to formation of pools and then pool fire.

Inhaling very high concentration of Benzene vapors can result in death, while inhalation of lower

concentration can cause drowsiness, dizziness, rapid heart rate, headaches and

unconsciousness. The major effect of exposure to Benzene for a prolonged period (365 days or



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longer) may adversely affect bone marrow and cause a decrease in red blood cells leading to

anemia. Benzene is a recognized carcinogenic. Refer to below tables for hazardous properties of

benzene. Table 14: Hazardous Properties of Benzene


1. LFL (%v/v) 1.4

2. UFL (%v/v) 8


4. Flash point (°C) - 11.1

5. Heat of combustion (KCAL/Kg) 9700

6. Normal Boiling point (°C) 80

Table 15: Toxic effects of Benzene


1. Odor threshold 0.16-320 ppm


3. Short Term Exposure Limit (STEL) (15 Minutes) 5


(for 30 min exposure)

500

4.3.4 TOLUENE

The hazards associated with Toluene are both toxic and flammable hazards. Toluene has a very

low flash point (4.40C), indicating that its vapor cloud easily gets ignited. If it is released at

temperatures higher than the normal boiling point it can flash significantly and would lead to high

entrainment of gas phase in the liquid phase. High entrainment of gas phase in the liquid phase

can lead to jet fires. On the other hand negligible flashing i.e. release of Toluene at temperatures

near boiling points would lead to formation of pools and then pool fire.

Inhaling very high concentration of Toluene vapors can result in death, while inhalation of lower

concentration can cause drowsiness, dizziness, rapid heart rate, headaches and

unconsciousness. The major effect of exposure to Toluene for a prolonged period (365 days or

longer) may adversely affect bone marrow and cause a decrease in red blood cells leading to

anemia. Toluene is a recognized carcinogenic. Refer Table below for hazardous properties of

Toluene



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Table 16: Hazardous Properties of Toluene


1. LFL (%v/v) 1.1

2. UFL (%v/v) 7.1

3. Normal Boiling point (°C) 111.11

Table 17: Toxic effects of Toluene



2. Short Term Exposure Limit (STEL) (15 Minutes) 5


(for 30 min exposure)

500



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5 HAZARD IDENTIFICATION 5.1 GENERAL A classical definition of hazard states that hazard is in fact the characteristic of

system/plant/process that presents potential for an accident. Hence all the components of a

system/plant/process need to be thoroughly examined in order to assess their potential for

initiating or propagating an unplanned event/sequence of events, which can be termed as an

accident.

In Risk Analysis terminology a hazard is something with the potential to cause harm. Hence the

Hazard Identification step is an exercise that seeks to identify what can go wrong at the major

hazard installation or process in such a way that people may be harmed. The output of this step is

a list of events that need to be passed on to later steps for further analysis.

The potential hazards posed by the facility were identified based on the past accidents, lessons

learnt and a checklist. This list includes the following elements.

Catastrophic Rupture of Pressure vessel

Large hole on outlet of process vessel

“Guillotine-Breakage” of pipe-work

Small hole, cracks or small bore failure (i.e. instrument tapping failure, drains/vents failure

etc.) in piping and vessels.

Flange leaks.

Storage Tank on fire

Leaks from pump glands and similar seals.

5.2 MODES OF FAILURE There are various potential sources of large leakage, which may release hazardous chemicals

and hydrocarbon materials into the atmosphere. These could be in form of gasket failure in

flanged joints, bleeder valve left open inadvertently, an instrument tubing giving way, pump seal

failure, guillotine failure of equipment/ pipeline or any other source of leakage. Operating

experience can identify lots of these sources and their modes of failure. A list of general

equipment and pipeline failure mechanisms is as follows:

Material/Construction Defects

Incorrect selection or supply of materials of construction

Incorrect use of design codes

Weld failures

Failure of inadequate pipeline supports

Pre-Operational Failures

Failure induced during delivery at site

Failure induced during installation

Pressure and temperature effects



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Overpressure

Temperature expansion/contraction (improper stress analysis and support design)

Low temperature brittle fracture (if metallurgy is incorrect)

Fatigue loading (cycling and mechanical vibration)

Corrosion Failures

Internal corrosion (e.g. ingress of moisture)

External corrosion

Cladding/insulation failure (e.g. ingress of moisture)

Cathodic protection failure, if provided

Failures due to Operational Errors

Human error

Failure to inspect regularly and identify any defects

External Impact Induced Failures

Dropped objects

Impact from transport such as construction traffic

Vandalism

Subsidence

Strong winds

Failure due to Fire

External fire impinging on pipeline or equipment

Rapid vaporization of cold liquid in contact with hot surfaces

5.3 SELECTED FAILURE CASES A list of selected failure cases was prepared based on process knowledge, engineering judgment,

experience, past incidents associated with such facilities and considering the general

mechanisms for loss of containment. A list of cases has been identified for the consequence

analysis study based on the following.

Cases with high chance of occurrence but having low consequence: Example of such

failure cases includes two-bolt gasket leak for flanges, seal failure for pumps, instrument

tapping failure, etc. The consequence results will provide enough data for planning routine

safety exercises. This will emphasize the area where operator's vigilance is essential.

Cases with low chance of occurrence but having high consequence (The example includes

Large hole on the outlet of pressure vessels, Catastrophic Rupture of Pressure Vessels,

etc.)

This approach ensures at least one representative case of all possible types of accidental

failure events, is considered for the consequence analysis. Moreover, the list below

includes at least one accidental case comprising of release of different sorts of highly

hazardous materials handled in the refinery. Although the list does not give complete failure



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incidents considering all equipment’s, units, but the consequence of a similar incident

considered in the list below could be used to foresee the consequence of that particular

accident.

For selected credible failure scenarios and likely consequences for units under Refinery

Expansion Project, refer Section-6.



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6 CONSEQUENCE ANALYSIS 6.1 GENERAL Consequence analysis involves the application of the mathematical, analytical and computer

models for calculation of the effects and damages subsequent to a hydrocarbon / toxic release

accident.

Computer models are used to predict the physical behavior of hazardous incidents. The model

uses below mentioned techniques to assess the consequences of identified scenarios:

Modeling of discharge rates when holes develop in process equipment/pipe work

Modeling of the size & shape of the flammable/toxic gas clouds from releases in the

atmosphere

Modeling of the flame and radiation field of the releases that are ignited and burn as jet fire,

pool fire and flash fire

Modeling of the explosion fields of releases which are ignited away from the point of release

The different consequences (Flash fire, pool fire, jet fire and Explosion effects) of loss of

containment accidents depend on the sequence of events & properties of material released

leading to the either toxic vapor dispersion, fire or explosion or both.

6.2 CONSEQUENCE ANALYSIS MODELLING 6.2.1 DISCHARGE RATE

The initial rate of release through a leak depends mainly on the pressure inside the equipment,

size of the hole and phase of the release (liquid, gas or two-phase). The release rate decreases

with time as the equipment depressurizes. This reduction depends mainly on the inventory and

the action taken to isolate the leak and blow-down the equipment.

6.2.2 DISPERSION

Releases of gas into the open air form clouds whose dispersion is governed by the wind, by

turbulence around the site, the density of the gas and initial momentum of the release. In case of

flammable materials the sizes of these gas clouds above their Lower Flammable Limit (LFL) are

important in determining whether the release will ignite. In this study, the results of dispersion

modeling for flammable materials are presented LFL quantity.

6.2.3 FLASH FIRE

A flash fire occurs when a cloud of vapors/gas burns without generating any significant

overpressure. The cloud is typically ignited on its edge, remote from- the leak source. The

combustion zone moves through the cloud away from the ignition point. The duration of the flash

fire is relatively short but it may stabilize as a continuous jet fire from the leak source. For flash

fires, an approximate estimate for the extent of the total effect zone is the area over which the

cloud is above the LFL.



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6.2.4 JET FIRE

Jet fires are burning jets of gas or atomized liquid whose shape is dominated by the momentum of

the release. The jet flame stabilizes on or close to the point of release and continues until the

release is stopped. Jet fire can be realized, if the leakage is immediately ignited. The effect of jet

flame impingement is severe as it may cut through equipment, pipeline or structure. The damage

effect of thermal radiation is depended on both the level of thermal radiation and duration of

exposure.

6.2.5 POOL FIRE

A cylindrical shape of the pool fire is presumed. Pool-fire calculations are then carried out as part

of an accidental scenario, e.g. in case a hydrocarbon liquid leak from a vessel leads to the

formation of an ignitable liquid pool. First no ignition is assumed, and pool evaporation and

dispersion calculations are being carried out. Subsequently late pool fires (ignition following

spreading of liquid pool) are considered. If the release is bunded, the diameter is given by the size

of the bund. If there is no bund, then the diameter is that which corresponds with a minimum pool

thickness, set by the type of surface on which the pool is spreading.

6.2.6 VAPOR CLOUD EXPLOSION

A vapor cloud explosion (VCE) occurs if a cloud of flammable gas burns sufficiently quickly to

generate high overpressures (i.e. pressures in excess of ambient). The overpressure resulting

from an explosion of hydrocarbon gases is estimated considering the explosive mass available to

be the mass of hydrocarbon vapor between its lower and upper explosive limits.

6.2.7 TOXIC RELEASE

The aim of the toxic risk study is to determine whether the operators in the plant, people occupied

buildings and the public are likely to be affected by toxic substances. Toxic gas cloud e.g. H2S,

chlorine, Benzene etc. was undertaken to the Immediately Dangerous to Life and Health

concentration (IDLH) limit to determine the extent of the toxic hazard Created as the result of loss

of containment of a toxic substance.

6.3 SIZE AND DURATION OF RELEASE Leak size considered for selected failure cases are listed below2. Leak sizes considered here are

representative hole sizes in the upstream / downstream circuit of particular equipment for which

failure scenario has been considered. Table 18: Size of Release

Failure Description Leak Size

Pump seal failure 6 mm hole size

Flange gasket failure 10 mm hole size

Instrument tapping failure 20 mm hole size

2 Refer to Guideline for Quantitative Risk assessment ‘Purple Book’.



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Failure Description Leak Size

Large Hole in the Piping 50 mm, complete rupture of 2” drain line at the Process

vessel outlet

Catastrophic Rupture Complete Rupture of the Pressure Vessels

The discharge duration is taken as 10 minutes for continuous release scenarios as it is

considered that it would take plant personnel about 10 minutes to detect and isolate the leak3.

6.4 DAMAGE CRITERIA In order to appreciate the damage effect produced by various scenarios, physiological/physical

effects of the blast wave, thermal radiation or toxic vapor exposition are discussed.

6.4.1 LFL OR FLASH FIRE

Hydrocarbon vapor released accidentally will spread out in the direction of wind. If a source of

ignition finds an ignition source before being dispersed below lower flammability limit (LFL), a

flash fire is likely to occur and the flame will travel back to the source of leak. Any person caught

in the flash fire is likely to suffer fatal burn injury. Therefore, in consequence analysis, the distance

of LFL value is usually taken to indicate the area, which may be affected by the flash fire.

Flash fire (LFL) events are considered to cause direct harm to the population present within the

flammability range of the cloud. Fire escalation from flash fire such that process or storage

equipment or building may be affected is considered unlikely.

6.4.2 THERMAL HAZARD DUE TO POOL FIRE, JET FIRE AND FIRE BALL

Thermal radiation due to pool fire, jet fire or fire ball may cause various degrees of burn on human

body and process equipment. The damage effect due to thermal radiation intensity is tabulated

below. Table 19: Damage Due to Incident Thermal Radiation Intensity

Incident Radiation Intensity

(Kw/M²) Type of Damage

37.5 Sufficient to cause damage to process equipment

32.0 Maximum flux level for thermally protected tanks containing flammable

liquid

12.5 Minimum energy required for piloted ignition of wood, melting of plastic

tubing etc.

8.0 Maximum heat flux for un-insulated tanks

4.0 Sufficient to cause pain to personnel if unable to reach cover within 20

seconds. However blistering of skin (1stdegree burns) is likely.

3 Release duration is based on Chemical Process Quantitative Risk Analysis, CCPS.



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The hazard distances to the 37.5 kW/m2, 32 kW/m2, 12.5 kW/m2, 8 kW/m2 and 4 kW/m2 radiation

levels, selected based on their effect on population, buildings and equipment were modeled using

PHAST.

6.4.3 VAPOR CLOUD EXPLOSION

In the event of explosion taking place within the plant, the resultant blast wave will have damaging

effects on equipment, structures, building and piping falling within the overpressure distances of

the blast. Tanks, buildings, structures etc. can only tolerate low level of overpressure. Human

body, by comparison, can withstand higher overpressure. But injury or fatality can be inflicted by

collapse of building of structures. The damage effect of blast overpressure is tabulated below.

Table 20: Damage Effects of Blast Overpressure

Blast Overpressure (PSI) Damage Level

5.0 Major structure damage

3.0 Oil storage tank failure

2.5 Eardrum rupture

2.0 Repairable damage, pressure vessels remain intact, light

structures collapse

1.0 Window pane breakage possible, causing some injuries

The hazard distances to the 5 psi, 3 psi and 2 psi overpressure levels, selected based on their

effects on population, buildings and equipment were modeled using PHAST.

6.4.4 TOXIC HAZARD

The inhalation of toxic gases can give rise to effects, which range in severity from mild irritation of

the respiratory tract to death. Lethal effects of inhalation depend on the concentration of the gas

to which people are exposed and on the duration of exposure. Mostly this dependence is

nonlinear and as the concentration increases, the time required to produce a specific injury

decreases rapidly.

The hazard distances to Immediately Dangerous to Life and Health concentration (IDLH) limit is

selected to determine the extent of the toxic hazard Created as the result of loss of containment of

a toxic substance.

6.5 CONSEQUENCE ANALYSIS FOR EXISTING UNITS UNDERGOING REVAMP/ MODIFICATIONS

This section discusses the consequences of selected failure scenarios for units whose affect

zones crosses the respective unit’s B/L and causes worst consequences. The consequence

distances are reported in tabular form for all weather conditions in Annexure-I and are



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represented graphically in Annexure-II for the all failure scenarios in a unit for worst weather

conditions.

6.5.1 APS

NOTE: Refer Figures 6.5.1.1 to 6.5.1.12 in Annexure-II

Instrument Tapping Failure at 11-P-1 A/B/C/D: From the results of consequence analysis it is

observed that Flash Fire, Jet Fire, Pool Fire and Overpressure distances will be realized. The LFL

hazardous zone may spread up to a distance of 62 m covering DIDC control room and major

portion of the APS unit area. The 37.5 & 12.5 Kw/m2 radiation intensity due to jet fire and pool fire

may affect most of the portions of the unit area as well as neighboring storage tank TK-102 based

on direction of the release. The 5 & 3 psi blast wave may extend up to a distance of 86 m & 92 m

respectively and crosses the B/L of the unit in all directions. DIDC control room, VPS unit and

storage tanks (TK-102/103), APS operator cabin may also get affected by the blast

overpressures.

Catastrophic Rupture of 11-D-2001: From the event outcome of the selected failure scenario it

can be observed that LFL may be extended up to a distance of 61 m and the LFL hazardous zone

may confined within the unit. The 5 & 3 psi blast wave may reach up to a distance of 119 m & 149

m respectively from the source point crossing the unit boundary. VPS unit, FRE-VPS unit, FRE-

APS unit, FCCU, Combination unit, Naphtha Pump House, CBFS loading facilities, Storage Tanks

(TK-101/102/103) and DIDC Control Room may get affected by the blast overpressures.

Instrument Tapping Failure at 11-P-2002 A/B: From the results of consequence analysis it can be

observed that LFL may reach up to a distance of 93 m from leak source and the LFL hazardous

zone may cover whole of APS unit & DIDC Control Room and some area in VPS &, Combination

units. The thermal radiation due to jet fire and pool fire may mostly restrict to the unit area. The 5

& 3 psi blast wave may spread up to a distance of 113 m & 121 m respectively from the source

point crossing the unit boundary, affecting VPS unit, FRE-APS unit, FCCU, Combination unit,

CBFS loading facilities and Storage Tanks (TK-101/102/103). DIDC Control Room, APS operator

cabin and Office building located near FRE-VPS unit may also get affected by the blast

overpressure.

Large Hole on bottom outlet of 11-T-2A (M): From the consequence results and graphs of the

selected failure scenario, it can be observed that LFL may spread up to a distance of 138 m

crossing the unit boundary. The LFL hazardous zone may cover upcoming VPS unit, FRE-VPS

unit, FRE-APS unit, Office building, FCCU, Combination unit, Naphtha Pump House, CBFS

loading facilities, Storage Tanks (TK-101/102/103) and DIDC Control Room. The jet fire radiation

intensities of 37.5 and 12.5 kW/m2 may spread up to a distance of 67 m and 82 m respectively. It

may also affect DIDC Control Room and Combination Unit partially. The 5 & 3 psi blast wave may

spread up to a distance of 164 m & 177 m respectively from the source point crossing the unit

boundary, affecting VPS unit, FRE-VPS unit, FRE-APS unit, Propane block, FCCU, Combination



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unit, Naptha Pump House, CBFS loading facilities, Gasoline blending unit and Storage Tanks

(TK-101/102/103). DIDC Control Room, Additive building and Office building near FRE-VPS unit

may also get affected by the blast overpressure. The pool fire radiation intensity12.5 kW/m2 may

be mostly restricting to the unit area.

Large Hole on outlet of 11-T-3A (M): From the event outcome of the selected failure scenario, it

can be observed that LFL may spread up to a distance of 136 m from leak source crossing the

unit boundary, covering upcoming VPS unit, FRE-VPS unit, FRE-APS unit, Office building, FCCU,

Combination unit, Naphtha Pump House, CBFS loading facilities, Storage Tanks (TK-

101/102/103) and DIDC Control Room. The jet fire radiation intensities of 37.5 and 12.5 kW/m2

may spread up to a distance of 67 m and 83 m respectively. It may also affect DIDC Control

Room, partially FRE-APS unit and partially Combination Unit. The 5 & 3 psi blast wave may


boundary in all directions. The blast wave may affects upcoming VPS unit, FRE-VPS unit, FRE-

APS unit, Propane block, V.L.G block, FCCU, Combination unit, Naphtha Pump House, Gasoline

Blending unit, N2 plant, CBFS loading facilities, cracked LPG treating unit and Storage Tanks (TK-

101/102/103). DIDC Control Room, Additive building and Office building near FRE-VPS unit may

also get affected by the blast overpressure. The pool fire radiation intensity12.5 kW/m2 will be

mostly restricted to the unit area.

Catastrophic Rupture of 11-D-1: From the consequence analysis of the selected failure scenario,

it can be observed that LFL may reach up to a distance of 278 m from leak source covering large

amount of area surrounding the unit. It covers upcoming VPS unit, FCCU, cracked LPG unit,

NHT-CCR and NHT-ISOM, storage tanks (TK-101/102/103/104/251B), railway track, FRE-VPS

unit, FRE-APS unit, new FCCU, Naphtha Pump House, Gasoline Blending unit, Euro-IV blending,

N2 plant, CBFS loading facilities, DIDC Control Room, Additive building, Office building near FRE-

VPS unit, Combination unit, NMP unit, Hexane maximization unit, CR. LPG block, MEX block,

LCN KERO block, CHEM block, ATF MEROX block, VLP MEA block, V.L.G block, Propane block,

DHT SRR and Boiler plant. The 5 & 3 psi blast wave may extend up to a distance of 357 m & 389

m respectively from leak source crossing the refinery boundary towards west. It may affect

upcoming VPS unit & New PRU, FCCU, cracked LPG unit, NHT-CCR and NHT-ISOM on northern

side and storage tanks (TK-101/102/103/104/251B) & railway track on western side. On the

southern side it affects FRE-VPS unit, FRE-APS unit, new FCCU, Naphtha Pump House,

Gasoline Blending unit, TEL building, Euro-IV blending, N2 plant, CBFS loading facilities, DIDC

Control Room, Additive building and Office building near FRE-VPS unit. On the eastern side it

covers Combination unit, DM plant, NMP unit, Hexane maximization unit, CR. LPG block, MEX

block, LCN KERO block, CHEM block, ATF MEROX block, VLP MEA block, V.L.G block, Propane

block, DHT SRR, Boiler plant, proposed H2 unit, DHT unit and SRU/SWS/ARU. The pool fire

radiation intensity of 12.5 kW/m2 may affect APS and Combination units partially.



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Instrument Tapping Failure at 11-P-2 A/B/C/D: From the event outcome of the selected failure

scenario it can be observed that LFL may be extended up to a distance of 82 m. The Jet Fire

Radiation of 37.5 & 12.5 kW/m2 may reach up to a distance of 43 m & 52 m respectively. The 5 &

3 psi blast wave may spread up to a distance of 101 m & 109 m respectively. The Pool Radiation

of 12.5 kW/m2 may reach up to a distance of 35 m. Based on consequence results it is observed

that the explosion hazard affect zone for this failure case may cover APS unit & DIDC Control

Room, APS operator cabin completely and some area in Combination unit & FRE-APS unit.

Large Hole on bottom outlet of 11-D-6 (N) (M): From the consequence results and graphs of the


crossing the unit boundary. The LFL hazardous zone may cover FRE-VPS unit, FRE-APS unit,

Office building, FCCU, Combination unit, DM plant, NMP unit, Hexane maximization unit, CR.

LPG block, MEX block, LCN KERO block, CHEM block, ATF MEROX block, VLP MEA block,

V.L.G block, Propane block and Boiler plant. The jet fire radiation intensities of 37.5 and 12.5

kW/m2 may spread up to a distance of 83 m and 100 m respectively. It may affect FRE-VPS unit,

Office building, Combination unit, CR. LPG block, MEX block, LCN KERO block, CHEM block,

ATF MEROX block, VLP MEA block, V.L.G block, Propane block and Boiler plant. The 5 & 3 psi

blast wave may spread up to a distance of 154 m & 163 m respectively from the source point

crossing the unit boundary. The blast wave may affect APS unit, FRE-VPS unit, Office building

near FRE-VPS, FRE-APS unit, Propane block, FCCU, Combination unit, DM plant, NMP unit,

Hexane maximization unit, CR. LPG block, MEX block, LCN KERO block, CHEM block, ATF

MEROX block, VLP MEA block, V.L.G block, Propane block, DHT, SRU/SWS/ARU and Boiler

plant.

Flange Leakage at 11-P-1023 A/B: From the results of consequence analysis it can be observed

that LFL may reach up to a distance of 20 m from leak source. The Jet Fire Radiation Intensity of

37.5 & 12.5 kW/m2 may spread up to a distance of 23 m & 28 m respectively. It may affect the

surrounding VLP MEA block, V.L.G block and Propane block. The Overpressure distances may

be mostly restricting to the unit area.

Large Hole on bottom outlet of 11-T-4 (M): From the consequence results and graphs of the


crossing the unit boundary in all directions. The LFL hazardous zone may cover FRE-VPS unit,

Office building, FCCU, Combination unit, DM plant, Hexane maximization unit, CR. LPG block,

MEX block, LCN KERO block, CHEM block, ATF MEROX block, VLP MEA block, V.L.G block,

Propane block and Boiler plant. The jet fire radiation intensities of 37.5 and 12.5 kW/m2 may

spread up to a distance of 79 m and 96 m respectively. It may affect FRE-VPS unit, Combination

unit, CR. LPG block, MEX block, LCN KERO block, CHEM block, ATF MEROX block, VLP MEA

block, V.L.G block, Propane block and Boiler plant. The 5 & 3 psi blast wave may spread up to a

distance of 132 m & 140 m respectively from the source point crossing the unit boundary. The



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blast wave may affect APS unit, FRE-VPS unit, Office building near FRE-VPS, FRE-APS unit,

Propane block, FCCU, Combination unit, DM plant, NMP unit, Hexane maximization unit, CR.

LPG block, MEX block, LCN KERO block, CHEM block, ATF MEROX block, VLP MEA block,

V.L.G block, Propane block, DHT, SRU/SWS/ARU and Boiler plant.

In addition to above scenarios, seal failure at 11-P-3 A/B and large hole on the bottom outlet of

11-T-2001 were also modeled. It is observed that hazardous affect zones might be restricted to

B/L’s of the unit depending upon the prevailing weather conditions at the time of release.

6.5.2 NHT/CCR

NOTE: Refer Figures 6.5.2.1 to 6.5.2.13 in Annexure- II

Catastrophic Rupture of Feed Surge Drum: From the event outcome of the selected failure

scenario, it was observed that LFL may spread up to a distance of 62 m crossing the unit and

covering NHT-ISOM partially. The 5 & 3 psi blast wave may spread up to a distance of 224 m and

217 m respectively from the source point crossing the unit boundary and affecting equipment in

NHT-ISOM. Satellite Rack room, administration building and equipment in cracked LPG treatment

unit might also get affected partially due to the blast wave.

Instrument Tapping Failure at Feed Charge Pump: From the consequence results and graphs of

the selected failure scenario, it was observed that LFL may spread up to a distance of 87 m

crossing the unit and covering NHT-ISOM partially. The jet fire thermal radiation intensities of 37.5

and 12.5 kW/m2 may spread up to a distance of 53 m and 64 m respectively crossing the unit and

covering NHT-ISOM partially. The 5 & 3 psi blast wave may spread up to a distance of 100 m &

107 m respectively from the source point covering equipment in NHT ISOM. The blast wave might

affect the Satellite Rack room partially.

Large Hole on bottom outlet of Separator: From the incident outcome of the selected failure

scenario, it was observed that LFL may spread up to a distance of 305 m crossing the refinery

boundary on the north and west sides of the unit affecting new fire station, NHT ISOM, New PRU,

Cracked LPG treating unit, DHT satellite work room, FCCU, hexane maximization unit,

compressor house, N2 plant, boiler area, EIL warehouse, PRIME G unit, main warehouse, satellite

rack room, administrative building & its annex buildings, new admin building compressor shed,

cooling towers, workshop, petrol pump and office building. The jet fire thermal radiation intensities

of 37.5 and 12.5 kW/m2 may spread up to a distance of 112 m and 137 m respectively covering

the whole unit. The radiation might cross the boundary affecting NHT ISOM, new fire station,

administration building and annexe-I and satellite rack room. The 5 & 3 psi blast wave may spread

up to a distance of 366 m & 391 m respectively from the source point crossing the refinery

boundary on the north and west sides of the unit affecting new fire station, NHT ISOM, New PRU,

Cracked LPG treating unit, combination unit, DHT satellite work room, hexane maximization unit,

FCCU, CR LPG unit, LCN MERO, ATF MEROX, CHEM block, compressor house, N2 plant, boiler



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area, EIL warehouse, PRIME G unit, SWS/ARU unit, main warehouse, satellite rack room,

administrative building & its annex buildings, new admin building compressor shed, cooling

towers, workshop, petrol pump and office building. H2 unit, DHDS unit, ARU & SWS unit might be

affected partially. The H2S IDLH concentration may have its effect up to a distance of 17.5 m on

grade level in the prevalent downwind direction.

Large Hole on bottom outlet of Stripper: From the incident outcome of the selected failure

scenario, it was observed that LFL may spread up to a distance of 102 m crossing the unit

boundary affecting NHT ISOM. The jet fire thermal radiation intensities of 37.5 and 12.5 kW/m2

may spread up to a distance of 80 m and 97 m respectively crossing the unit boundary. The

radiation might cross the boundary affecting NHT ISOM partially. The 5 & 3 psi blast wave may

spread up to a distance of 123 m & 131 m respectively from the source point covering the unit and

crossing the unit boundary affecting new fire station, administrative building and equipment in

NHT ISOM. The benzene IDLH concentration may have its effect up to a distance of 80 m on

grade level in the prevalent downwind direction.

Catastrophic Rupture of Stripper Receiver: From the event outcome of the selected failure


covering NHT-ISOM partially. The 5 & 3 psi blast wave may spread up to a distance of 103 m and


NHT-ISOM. Satellite Rack room and administration building might also get affected partially due

to the blast wave.

Instrument Tapping Failure at Separator Pumps - Toxic: From the consequence results and

graphs of the selected failure scenario, it was observed that LFL may spread up to a distance of

100 m crossing the unit and covering NHT-ISOM. The jet fire thermal radiation intensities of 37.5


covering NHT-ISOM partially. The 5 & 3 psi blast wave may spread up to a distance of 123 m &

132 m respectively from the source point covering equipment in NHT ISOM. The blast wave might

affect the Satellite Rack room and administration building partially. The toluene IDLH

concentration may have its effect up to a distance of 242 m on grade level in the prevalent

downwind direction.

Catastrophic Rupture of Re-contact Drum: From the event outcome of the selected failure


covering NHT-ISOM and satellite rack room. Administration building and PRIME-G units might

also be covered partially. The 5 & 3 psi blast wave may spread up to a distance of 173 m and 189

m respectively from the source point crossing the unit boundary and affecting equipment in NHT-

ISOM, Satellite Rack room, administration building & its annexe buildings, DHT satellite work



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room and boiler area. The new admin building and equipment in PRIME-G unit and cracked LPG

treatment unit might also get affected partially due to the blast wave.

Flange Leakage at Stabilizer Feed/Bottom Exchanger-Toxic: From the consequence modeling of


crossing the unit and covering NHT-ISOM partially. The jet fire thermal radiation intensities of 37.5


covering NHT-ISOM partially. The 5 & 3 psi blast wave may spread up to a distance of 50 m & 54

m respectively from the source point covering equipment in NHT ISOM partially. The toluene

IDLH concentration may have its effect up to a distance of 89 m on grade level in the prevalent

downwind direction.

Large Hole on the Bottom Outlet of Stabilizer Receiver: From the incident outcome of the selected

failure scenario, it was observed that LFL may spread up to a distance of 176 m crossing the unit

boundary affecting new fire station, cracked LPG treating unit, NHT ISOM, satellite rack room,

administration building and annexe-I. The jet fire thermal radiation intensities of 37.5 and 12.5

kW/m2 may spread up to a distance of 92 m and 112 m respectively crossing the unit boundary

affecting NHT ISOM. The 5 & 3 psi blast wave may spread up to a distance of 211 m & 226 m

respectively from the source point covering the unit and crossing the unit boundary affecting new

fire station, satellite rack room, administrative building & its annexe buildings and equipment in

NHT ISOM, PRIME-G and cracked LPG treating unit.

Instrument Tapping Failure at Stabilizer Overhead pumps: From the consequence results and


70 m crossing the unit and covering NHT-ISOM partially. The jet fire thermal radiation intensities

of 37.5 and 12.5 kW/m2 may spread up to a distance of 46 m and 55 m respectively crossing the

unit and covering NHT-ISOM partially. The 5 & 3 psi blast wave may spread up to a distance of 76

m & 82 m respectively from the source point covering equipment in NHT ISOM.

In addition to above scenarios, Instrument Tapping Failure at Recycle Compressor, Instrument

Tapping Failure at Net Gas Compressor 2nd Stage- Toxic and Flange Leakage at Stripper Reflux

Pump were also modeled. It is observed that hazardous affect zones might be restricted to B/L’s

of the unit depending upon location of the equipment and prevailing weather conditions at the time

of release.

6.5.3 PRIME G


Large Hole on the bottom outlet of SHU Feed Surge Drum: From the consequence modeling of

the selected failure scenario, it was observed that LFL may spread up to a distance of 169 m and

the LFL hazardous zone may cover NHT-CCR, New PRU, SWS/ARU, Boiler area, Main Ware

House, SG-12, SRR, Annex-I building, Annex-II building, Workshop, Petrol Pump, Office building



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and Administration building. The jet fire thermal radiation intensities of 37.5 and 12.5 kW/m2 may

spread up to a distance of 76 m and 93 m respectively covering SRR, SG-12 and Main Ware

House partially. The 5 & 3 psi blast wave may spread up to a distance of 217 m & 239 m

respectively from the source point crossing the unit boundary, affecting NHT-CCR, New PRU,

NHT-ISOM, Boiler Area, SWS/ARU on north east of the unit, SWS/ARU on east of the unit, DM

plant, N2 plant, SG-12, Cooling Tower on west side of the unit, Cooling Tower on north east of the

unit, BFW Cooling Tower, SRR, DHT SRR, Cracked LPG Treating Unit, Petrol Pump, partially

DHDS and Storage Tanks TK-371/372/373/365/366. Annex-I building, Annex-II building, Admin

building, New Admin building, Office building, Administration building, Contractor Shed, Workshop

and Main Ware House may also get affected by the blast overpressure. The pool fire radiation

intensity of 12.5 kW/m2 is well contained within the unit.

Instrument tapping failure at SHU Feed Pump: From the incident outcome of the selected failure

scenario, it was observed that LFL may spread up to a distance of 88 m covering SG-12 and

partially main Ware House. The jet fire radiation intensities of 37.5 and 12.5 kW/m2 may be

confined within the unit. The 5 & 3 psi blast wave may spread up to a distance of 100 m & 108 m

respectively from the source point crossing the unit boundary, affecting SG-12, SRR, Boiler Area,

partially SWS/ARU and partially NHT-CCR. Main Ware House may also get affected by the blast

overpressure.

Instrument Tapping Failure at Light Gasoline Pumps: From the consequence results and graphs

of the selected failure scenario, it was observed that LFL may spread up to a distance of 54 m

covering SG-12 partially. The jet fire thermal radiation intensities of 37.5 and 12.5 kW/m2 may

spread up to a distance of 40 m and 48 m respectively crossing the unit B/L and may affect the

SG-12. The 5 & 3 psi blast wave may spread up to a distance of 62 m & 67 m respectively from

the source point damaging SG-12.

Catastrophic Rupture of Splitter Reflux Drum: From the consequence analysis, it was observed

that LFL may spread up to a distance of 183 m crossing the unit boundary and extending into

NHT-CCR, New PRU, Boiler area, DM plant, N2 plant, SWS/ARU on north east of the unit, storage

Tanks TK-372/373, Main Ware House, SRR, Office building, Petrol Pump, Annex-I building,

Annex-II building, Workshop and Administration building. The 5 & 3 psi blast wave may spread up

to a distance of 224 m & 245 m respectively from the source point crossing the unit boundary,

affecting NHT-CCR, NHT-ISOM, New PRU, Boiler Area, SWS/ARU on north east of the unit,

SWS/ARU on east of the unit, DM plant, N2 plant, SG-12, Cooling Tower on west side of the unit,

Cooling Tower on north east of the unit, BFW Cooling Tower, SRR, DHT SRR, Cracked LPG

Treating Unit, Petrol Pump, partially DHDS & H2 units and Storage Tanks TK-

370/371/372/373/365/366. The blast zone may also cover Annex-I building, Annex-II building,

Admin building, New Admin building, Office building, Administration building, Contractor Shed,



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Workshop, Main Ware House and Mosque. The pool fire radiation intensity of 12.5 kW/m2 is well

contained within the unit.

Large Hole on bottom outlet of Separator Drum: From the consequence results and graphs of the

selected failure scenario, it was observed that LFL may spread up to a distance of 285 m crossing

the refinery boundary on north side. The LFL hazardous zone may cover NHT-CCR, NHT-ISOM,

New PRU, Boiler Area, SWS/ARU on north east of the unit, SWS/ARU on east of the unit, DM

plant, N2 plant, SG-12, Cooling Tower on west side of the unit, Cooling Tower on north east of the

unit, BFW Cooling Tower, SRR, DHT SRR, Cracked LPG Treating Unit, Petrol Pump, DHDS, H2

unit, Hexane Maximization unit, upcoming VPS unit, FCCU & NMP partially and Storage Tanks

TK-364/365/366/369/370/371/372/373. The jet fire radiation intensities of 37.5 and 12.5 kW/m2

may spread up to a distance of 104 m and 128 m respectively. It may affect NHT-CCR, SRR,

Boiler Area and Main Ware house partially. The 5 & 3 psi blast wave may spread up to a distance

of 346 m & 371 m respectively from the source point crossing the refinery boundary towards north

side. The blast zone may spread up to NHT-CCR, NHT-ISOM, New PRU, Boiler Area, SWS/ARU

on north east of the unit, SWS/ARU on east of the unit, SRU, DM plant, N2 plant, SG-12, Cooling

Tower on west side of the unit, Cooling Tower on north east of the unit, BFW Cooling Tower,

SRR, DHT SRR, Cracked LPG Treating Unit, Petrol Pump, DHDS, H2 unit, Hexane Maximization

unit, upcoming VPS unit, Propane block, V.L.G block, VLP MEA block, ATF Merox block, CHEM

block, CR LPG block, LCN MERO block, FCCU, NMP unit, Combination unit and Storage Tanks

TK-118/119/363/364/365/366/367/368/369/370/371/372/373. Annex-I building, Annex-II building,

Admin building, New Admin building, Office building, Administration building, Contractor Shed,

Workshop, Main Ware House, Operator building near SRU, CISF building near main gate, new

Fire Station, and Mosque may also get affected by the blast overpressure. The pool fire radiation

intensities of 37.5 and 12.5 kW/m2 may spread up to a distance of 101 m and 144 m respectively

going beyond the unit and may reach up to NHT-CCR, New PRU, Boiler area, SG-12, main Ware

House, SRR, SWS/ARU located on north east of the unit, administration building and Annex-II

building.

Instrument Tapping Failure at Separator Drum Overhead - Toxic: From the event outcome of the

selected failure scenario it can be observed that LFL may be extended up to a distance of 17 m.

The Jet Fire and Pool Fire radiation is not realized. The 5 & 3 psi blast overpressures may travel

up to a distance of 13 m & 14 m respectively. The IDLH H2S concentration may not reach to the

ground but it can spread up to a distance of 18 m from the leak source at height of 10 m from the

ground.

Large hole at Stabilizer bottom outlet: From the consequence results and graphs of the selected

failure scenario, it was observed that LFL may spread up to a distance of 106 m covering SG-12,

Warehouse, SRR and NHT/CCR partially. The jet fire thermal radiation intensities of 37.5 and

12.5 kW/m2 may spread up to a distance of 68 m and 82 m respectively crossing the unit B/L and



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may affect the SG-12. The 5 & 3 psi blast wave may spread up to a distance of 124 m & 132 m

respectively from the source point damaging SG-12, Warehouse, SRR and NHT/CCR partially.

Catastrophic Rupture of Stabilizer Reflux Drum: From the consequence analysis, it was observed

that LFL may spread up to a distance of 83 m crossing the unit’s B/L extending up to main Ware

House on the north and SG-12 on the west side. The 5 & 3 psi blast wave may spread up to a

distance of 100 m & 108 m respectively from the source point and into neighboring units affecting

some area in SRR, Boiler Area, NHT-CCR and SWS/ARU,. These blast waves may also affect

main Ware House located on north side of the unit.

In addition to the above scenarios, instrument tapping failure at Separator Drum Overhead and

flange leak at Quench pump & Stabilizer Bottom pump were also modeled and it was observed

that hazardous effect zones might be restricted within B/L of the unit depending upon the

prevailing weather condition at time of release.

6.5.4 NHDT/ISOM


Catastrophic Rupture of Feed Surge Drum: From the event outcome of the selected failure


covering NHT-CCR and new fire station. The 5 & 3 psi blast wave may spread up to a distance of

199 m and 218 m respectively from the source point crossing the unit boundary and affecting

equipment in NHT-CCR and cracked LPG treating unit. New fire station, Satellite Rack room,

administration building & its annexe buildings and some area of FCCU might fall under the blast

effect zone. The pool fire thermal radiation intensity of 12.5 kW/m2 may spread up to a distance

of 24 m crossing the unit and covering NHT-CCR partially.

Instrument Tapping Failure at Feed Pump: From the consequence results and graphs of the


the unit and covering NHT-CCR. The jet fire thermal radiation intensities of 37.5 and 12.5 kW/m2

may spread up to a distance of 50 m and 61 m respectively crossing the unit and covering NHT-

CCR partially. The 5 & 3 psi blast wave may spread up to a distance of 112 m & 121 m

respectively from the source point covering the new fire station and equipment in NHT ISOM.

Large Hole on bottom outlet of Separator Drum - Toxic: From the incident outcome of the selected

failure scenario, it was observed that LFL may spread up to a distance of 313 m crossing the plant

boundary on west side and crossing the unit boundary affecting the new fire station, cracked LPG

treating unit, FCCU, combination unit, hexane maximization unit, CR LPG, Merox, compressor

house, DM plant, N2 plant, PRIME-G unit, NHT CCR, satellite rack room, administration building &

its annexe buildings and new admin building. It might spread over main warehouse and workshop

partially. The jet fire thermal radiation intensities of 37.5 and 12.5 kW/m2 may spread up to a

distance of 111 m and 135 m respectively crossing the unit boundary affecting NHT CCR. The 5 &



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3 psi blast wave may spread up to a distance of 381 m & 408 m respectively from the source point

crossing the plant boundary on west and north sides and covering the new fire station, cracked

LPG treating unit, FCCU, combination unit, FRE-APS unit, FRE-VPS unit, hexane maximization

unit, CR LPG, Merox, New PRU, compressor house, DM plant, N2 plant, NMP unit, PRIME-G unit,

NHT CCR, satellite rack room, administration building & its annexe buildings, new admin building,

main warehouse and workshop. The H2S IDLH concentration might affect personnel up to a

distance of 19 m on grade level in the direction of predominant wind direction.

Large Hole on bottom outlet of Stripper Bottom - Toxic: From the incident outcome of the selected


boundary affecting NHT CCR. The jet fire thermal radiation intensities of 37.5 and 12.5 kW/m2

may spread up to a distance of 82 m and 99 m respectively crossing the unit boundary affecting

NHT CCR. The 5 & 3 psi blast wave may spread up to a distance of 123 m & 132 m respectively

from the source point covering the unit and crossing the unit boundary affecting equipment in NHT

CCR and some areas of cracked LPG treating unit. The benzene IDLH concentration might affect

personnel up to a distance of 83 m on grade level in the direction of predominant downwind

direction.

Catastrophic Rupture of Isomerization Feed Surge Drum: From the event outcome of the selected


and covering NHT-CCR and new fire station. Satellite rack room and administration building may

come under the LFL zone. The 5 & 3 psi blast wave may spread up to a distance of 215 m and


NHT-CCR and cracked LPG treating unit. New fire station, Satellite Rack room, administration

building & its annexe buildings and some area of FCCU might fall under the blast zone. The pool

fire thermal radiation intensity of 12.5 kW/m2 may spread up to a distance of 32 m crossing the

unit and covering NHT-CCR partially.

Instrument Tapping Failure at Aromatics Hydrogenation Pump: From the consequence results

and graphs of the selected failure scenario, it was observed that LFL may spread up to a distance

of 95 m crossing the unit and covering NHT-CCR and new fire station partially. The jet fire thermal

radiation intensities of 37.5 and 12.5 kW/m2 may spread up to a distance of 56 m and 67 m

respectively crossing the unit and covering NHT-CCR and new fire station. The 5 & 3 psi blast

wave may spread up to a distance of 112 m & 120 m respectively from the source point covering

new fire station and equipment in NHT CCR.

Large Hole on bottom outlet of Hydrogenation Reactor Flash Drum: From the incident outcome of


crossing the unit boundary affecting NHT/CCR. The jet fire thermal radiation intensities of 37.5

and 12.5 kW/m2 may spread up to a distance of 90 m and 109 m respectively crossing the unit



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boundary affecting NHT CCR partially. The 5 & 3 psi blast wave may spread up to a distance of

155 m & 165 m respectively from the source point covering the unit and crossing the unit

boundary affecting new fire station and equipment in NHT CCR.

Large Hole on bottom outlet of Stabilizer: From the consequence analysis of the selected failure


covering NHT-CCR. The jet fire thermal radiation intensities of 37.5 and 12.5 kW/m2 may spread

up to a distance of 82 m and 99 m respectively crossing the unit and covering NHT-CCR and new

fire station. The 5 & 3 psi blast wave may spread up to a distance of 112 m & 120 m respectively

from the source point covering new fire station and equipment in NHT CCR.

Catastrophic Rupture of Stabilizer Reflux Drum: From the event outcome of the selected failure


covering NHT-CCR partially. The 5 & 3 psi blast wave may spread up to a distance of 121 m and


NHT-CCR and Fire station.

Instrument Tapping Failure at Stabilizer Reflux Pump: From the consequence results and graphs

of the selected failure scenario, it was observed that LFL may spread up to a distance of 49 m

crossing the unit and covering NHT-CCR partially. The jet fire thermal radiation intensities of 37.5


covering NHT-CCR partially. The 5 & 3 psi blast wave may spread up to a distance of 51 m & 55

m respectively from the source point covering equipment in NHT CCR partially.

Large Hole on bottom outlet of Deisohexanizer Reflux Drum: From the incident outcome of the


the unit boundary affecting new fire station and NHT/CCR. The jet fire thermal radiation intensities

of 37.5 and 12.5 kW/m2 may spread up to a distance of 66 m and 81 m respectively crossing the

unit boundary affecting NHT/CCR partially. The 5 & 3 psi blast wave may spread up to a distance

of 180 m & 195 m respectively from the source point covering the unit and crossing the unit

boundary affecting new fire station, satellite rack room, administrative building and equipment in

NHT CCR and cracked LPG treating unit. The blast wave might also affect FCCU and boiler area.

The pool fire thermal radiation intensities of 12.5 kW/m2 may cross the unit boundary affecting

NHT CCR partially.

Instrument Tapping Failure at Isomerate Storage Pumps: From the consequence results and


88 m crossing the unit and covering NHT-CCR partially. The jet fire thermal radiation intensities of

37.5 and 12.5 kW/m2 may spread up to a distance of 46 m and 56 m respectively crossing the unit

and extending into NHT-CCR. The 5 & 3 psi blast wave may spread up to a distance of 99 m &



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106 m respectively from the source point covering equipment in NHT CCR. The pool fire thermal

radiation intensity of 37.5 kW/m2 and 12.5 kW/m2 may be confined within the unit.

Large Hole on bottom outlet of LPG Splitter Reflux Drum: From the incident outcome of the


the unit boundary affecting NHT/CCR. The jet fire thermal radiation intensities of 37.5 and 12.5

kW/m2 may spread up to a distance of 87 m and 103 m respectively crossing the unit boundary

affecting NHT CCR. The 5 & 3 psi blast wave may spread up to a distance of 143 m & 152 m

respectively from the source point covering the unit and crossing the unit boundary affecting

equipment in NHT/CCR. New fire station and cracked LPG treating unit might be affected

partially.

Instrument Tapping Failure at LPG Product Pump: From the consequence results and graphs of


crossing the unit and covering NHT-CCR. The jet fire thermal radiation intensities of 37.5 and 12.5

kW/m2 may spread up to a distance of 46 m and 54 m respectively crossing the unit and covering

NHT-CCR partially. The 5 & 3 psi blast wave may spread up to a distance of 63 m & 67 m

respectively from the source point covering equipment in NHT CCR partially.

In addition to the above discussed scenarios, instrument tapping failure at H2 Make-up

Compressor, seal failure at Isomerization Reactor Feed Pumps & Separator Drum Bottom Pump

and flange leakage at LPG Splitter Bottom Pump, LPG Splitter Reflux Pump & Stripper Reflux

Pump were also modeled and it was observed that hazardous effect zones might be restricted

within B/L of the unit depending upon the prevailing weather condition at time of release.

6.5.5 DHT


Large Hole on bottom outlet of Feed Surge Drum: From the consequence results and graphs of

the selected failure scenario, it was observed that LFL may spread up to a distance of 97 m and

LFL zone may cover proposed HGU unit and the west side boiler plant cooling tower. The jet fire

radiation intensities of 37.5 and 12.5 kW/m2 may spread up to a distance of 65 m and 81 m

respectively and it may affect newly proposed HGU unit partially. The 5 & 3 psi blast wave may


boundary and it may reach up to southern proposed HGU unit, northern SRU/ARU/SWS, western

boiler plant and eastern storage tank TK-111. The pool fire radiation intensity of 12.5 kW/m2 may

affect some area in newly proposed HGU unit.

Instrument Tapping Failure at Charge Pumps: From the incident outcome of the selected failure

scenario, it was observed that LFL may spread up to a distance of 83 m covering DHT and the

newly proposed HGU partially. The jet fire radiation intensities of 37.5 and 12.5 kW/m2 may affect

DHT and proposed HGU partially. The 5 & 3 psi blast wave may spread up to a distance of 99 m



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& 106 m respectively from the source point crossing the unit boundary, affecting neighboring

SRU/ARU/SWS and proposed HGU unit. Boiler plant located on west side of the unit and storage

tank TK-111 located on east side of the unit may also get affected by the blast overpressure.

Catastrophic Rupture of Separator: From the incident outcome analysis of selected failure

scenario, it is observed that LFL for this may reach up to a distance of 323 m from the leak source

and crosses the B/L of the unit in all directions. It covers the newly proposed HGU,

SRU/SWS/ARU, H2 unit, DM plant, NMP unit, Hexane maximization unit, storage tanks (TK-

301/302/311/312/1003/1004/107/108/261/359/360/362/304/354/110/111/112/113), CR-LPG block

, MEX block, LCN KERO block, CHEM block, ATF MEROX block, VLP MEA block, V.L.G block,

Propane block, FRE APS unit, Office building located near FRE-VPS unit, FRE-VPS unit, new

FCCU, Combination unit, Site Office, power cable company and boiler plant & its associated

facilities. The 5 & 3 psi blast wave may reach up to a distance of 397 m & 430 m respectively and

crosses the refinery boundary towards east side. The 5 & 3 psi blast wave affects

SRU/ARU/SWS/TGTU, SRU/SWS/ARU, H2 unit, New PRU and DHDS unit located on northern

side of the unit. On the eastern side the blast wave affects storage tanks (TK-110/111/112/113)

and fire water storage & transfer facilities. On the western side it affects DM plant, NMP unit,

Cracked LPG unit, DHT SRR, Boiler area, Hexane maximization unit, CR. LPG block, MEX block,


FRE APS unit, Office building located near FRE-VPS unit, FRE-VPS unit, DIDC control room, new

FCCU, Combination unit, Site Office, FCCU, EURO IV / Gasoline blending facilities, several

storage tanks & pumping stations and boiler plant & its associated facilities. On the southern side

it affects newly proposed HGU, CPP unit and several storage tanks.

Instrument Tapping Failure at Separator Overhead – Toxic: From the consequence analysis, it

was observed that LFL may spread up to a distance of 24 m crossing the unit boundary reaching

up to east side road ‘Cave H’. The jet fire radiation intensities of 37.5 and 12.5 kW/m2 may be

confined within the unit. The 5 & 3 psi blast wave may spread up to a distance of 26 m & 28 m

respectively from the source point. The IDLH H2S concentration may not reach to the ground but it

can spread up to a distance of 50 m from the leak source at height of 9 m from the ground.

Instrument Tapping Failure at Recycle Gas Compressor: From the consequence results and

graphs it can be observed that LFL may extend up to a distance of 30 m covering DHTU & HGU

partially. The Jet Fire Radiation of intensity 37.5 & 12.5 kW/m2 may affect some area of DHT &

neighbouring proposed HGU. The 5 & 3 psi blast wave may extend up to a distance of 28 m & 31

m respectively crossing the unit boundary covering some area in newly proposed HGU.

Instrument Tapping Failure at Make-up Gas Compressor: From the event outcome of the selected

failure scenario it can be observed that LFL may be extended up to a distance of 28 m crossing



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the unit boundary covering some area in newly proposed HGU. The Jet Fire Radiation and the

Blast Overpressure may affect some equipment in DHT & new proposed HGU.

Large Hole on bottom outlet of Stripper Receiver-Toxic: From the consequence analysis of the

selected failure scenario, it can be observed that LFL may be extended up to a distance of 241 m

from leak source covering large amount of area surrounding the unit. It covers SRU/ARU/SWS on

northern side and storage tanks (TK-111/110, CP-TK-4) & fire water pumps on eastern side. On

the western side it covers DM plant, NMP unit, Hexane maximization unit, CR. LPG block, MEX

block, LCN KERO block, CHEM block, ATF MEROX block, VLP MEA block, V.L.G block, Propane

block, FRE-VPS unit, new FCCU, storage tanks (TK-301/302/311/312) and boiler plant & its

associated facilities. On the southern side it covers newly proposed HGU and storage tanks (TK-

107/108). The Jet Fire Radiation Intensity of 37.5 & 12.5 kW/m2 may spread up to a distance of

94 m & 116 m respectively. It may engulf the surrounding SRU/SWS/ARU, proposed HGU, DM

plant, cooling tower and other water related facilities located on west side of the unit. The 5 & 3

psi blast wave may extend up to a distance of 302 m & 326 m respectively and crosses the B/L of

the unit in all directions. On the northern side it affects New SRU/ARU/SWS, H2 unit and DHDS

unit. On the eastern side blast wave covers storage tanks (TK-110/111/112/113) and fire water

storage & transfer facilities. On the western side it affects DM plant, NMP unit, Hexane

maximization unit, CR. LPG block, MEX block, LCN KERO block, CHEM block, ATF MEROX

block, VLP MEA block, V.L.G block, Propane block, FRE APS unit, Office building located near

FRE-VPS unit, FRE-VPS unit, Naphtha pump house, DIDC control room, new FCCU,

Combination unit, Site Office, FCCU, storage tanks (TK-301/302/311/312/1003/1004) and boiler

plant & its associated facilities. On the southern side it affects newly proposed HGU and storage

tanks (TK-107/108/261/457/304/354/359). The pool fire radiation intensity of 37.5 & 12.5 kW/m2

may affect neighboring SRU/SWS/ARU, newly proposed HGU, DM plant and boiler plant & its

associated facilities. The toxic hazard distances due to H2S IDLH concentration of 100 ppm may

extend up to 549 m at ground level and crosses the refinery boundary towards east side

depending upon the prevailing wind direction at the time of release.

Flange Leakage at Stripper Overhead Pumps – Toxic: Based on the consequence results it is

observed that The LFL hazardous zone, the Jet Fire Radiation and the Blast Overpressure for this

failure case may be contained within the B/L’s of the unit. The toxic hazard distances due to H2S

IDLH concentration of 100 ppm may extend up to 151 m at ground level depending upon the

prevailing wind direction at the time of release. The toxic hazardous zone may cover neighboring

SRU/SWS/ARU, proposed HGU, DM plant, CHEM block, ATF MEROX block, VLP MEA block

and boiler plant & its associated facilities.

Catastrophic Rupture of Product Fractionator Receiver: From the consequence results and

graphs it can be observed that LFL may extend up to a distance of 120 m crossing the unit B/L

covering proposed HGU, SRU/SWS/ARU, DM plant and Boiler plant. The 5 & 3 psi blast wave



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may reach up to a distance of 175 m & 213 m respectively crossing the unit boundary affecting

neighbouring SRU/SWS/ARU, proposed HGU and storage tanks TK-110/111 completely. On the

western side it affects DM plant, NMP unit, Hexane maximization unit, CR. LPG block, MEX block,


FRE-VPS unit, new FCCU, Site Office near Combination unit, storage tanks (TK-

301/302/311/312) and Boiler plant & its associated facilities.

Instrument Tapping Failure at Kerosene Product Pump: From the event outcome of the selected

failure scenario it can be observed that LFL may be extended up to a distance of 59 m. The Jet

Fire Radiation of 37.5 & 12.5 kW/m2 may reach up to a distance of 38 m & 46 m respectively. The

5 & 3 psi blast wave may spread up to a distance of 63 m & 69 m respectively. Based on

consequence results it is observed that the hazardous affect zone for this failure case may cover

DHT and neighbouring SRU/SWS/ARU partially.

In addition to the above scenarios, seal failure at Diesel Product pumps & and flange leak at

Product Fractionator Net Overhead Pumps & Naphtha Trim Coolers were also modeled and it

was observed that hazardous effect zones might be restricted within B/L of the unit depending

upon the prevailing weather condition at the time of release.

6.6 CONSEQUENCE ANALYSIS FOR NEW PROPOSED UNITS This section discusses the consequences of selected failure scenarios for units whose affect

zones crosses the respective unit’s B/L and causes worst consequences. The consequence

distances are reported in tabular form for all weather conditions in Annexure-I and are

represented graphically in Annexure-III for the all failure scenarios in a unit for worst weather

conditions.

6.6.1 HGU

NOTE: Refer Figures 6.6.1.1 to 6.6.1.5 in Annexure-III

Large hole on Bottom Outlet of Naphtha Surge Drum: From the incident outcome analysis of the

selected failure scenario it is observed that LFL hazard distance is extended up to 186 m. The Jet

Fire radiation intensity of 37.5 & 12.5 kW/m2 would extend up to a distance of 86 m & 105 m

respectively. The Pool Fire radiation intensity of 37.5 kW/m2 is not realized & 12.5 kW/m2 will

extend up to a distance of 43 m. The 5 & 3 psi blast waves may reach up to a distance of 240 m &

263 m.

Based upon the consequence analysis, it can be observed that though selected failure scenario

have low probability of occurrence but if realized at any instant in plant life, the hazardous affect

zones will be spreading throughout the unit & shall also be extended beyond the B/L’s of the unit

affecting nearby facilities.



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Flange Leakage at Naphtha Pump: From the consequence analysis results for this failure

scenario it is realized that LFL shall travel up to a distance of 38 m. The Jet Fire Radiation

Intensity of 37.5 & 12.5 kW/m2 may reach up to a distance of 30 m & 46 m respectively. The 5 & 3

psi blast wave may travel up to a distance of 39 m & 42 m respectively.

By analyzing consequence modeling results it is observed that hazardous affect zone for this

event will go beyond the B/L’s of the unit and may cause damage to the nearby facilities.

Large Hole on Bottom Outlet of LPG Surge Drum: From the consequence results and graphs of

the selected credible scenario, it can be concluded that LFL may be extended up to a distance of

130 m. The Jet Fire radiation intensity of 37.5 & 12.5 kW/m2 would spread up to a distance of 82

m & 99 m respectively. The 5 & 3 psi blast overpressures travel up to a distance of 149 m & 160

m respectively.

By analyzing the above results, it can be observed that hazardous affect zones for the selected

credible failure scenario shall be spreading throughout the unit and also extended beyond the

B/L’s of the unit irrespective of the location of equipment, affecting nearby facilities.

Instrument Tapping Failure at LPG Feed Pump: From the event outcome of the selected failure


radiation intensity of 37.5 & 12.5 kW/m2 would be getting extended up to 53 m & 64 m

respectively. The 5 & 3 psi blast waves may reach up to a distance of 87 m & 93 m respectively.

Based on consequence results it could be inferred that consequence affect zone might be getting

extended beyond the B/L’s of the unit.

In addition to above scenarios, Instrument Tapping Failure at H2 Circulation Compressor was also

modeled. It is observed that hazardous affect zones might be restricted to B/L’s of the unit

depending upon location of the equipment and prevailing weather conditions at the time of

release.

6.6.2 VBU


Large hole on Bottom Outlet of Main Fractionator Reflux Drum: From the consequence analysis of

the selected failure scenario it is observed that LFL hazard distance is extended up to a distance

of 207 m. The Jet Fire Radiation Intensity of 37.5 & 12.5 kW/m2 can extend up to a distance of 80

m & 99 m respectively. The 5 & 3 psi blast wave may spread up to a distance of 270 m and 296 m

respectively.

Based upon the consequence analysis modeling and by analyzing results, it can be observed that

hazardous affect zones will be spreading throughout the unit & shall also be extended beyond the

B/L’s of the unit affecting nearby facilities, irrespective of the location of the equipment in the unit.



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Instrument Tapping Failure at Fractionator Overhead Pumps: From the consequence results and

graphs of the selected credible scenario, it can be concluded that LFL may be extended up to a

distance of 107 m. The Jet Fire radiation intensity of 37.5 & 12.5 kW/m2 would spread up to a

distance of 46 m & 56 m respectively. The Pool Fire Radiation Intensity of 37.5 kW/m2 & 12.5

kW/m2 can extend up to a distance of 22 m & 31 m respectively. The 5 & 3 psi blast

overpressures may travel up to a distance of 123 m & 132 m respectively.

Based upon the above discussion it may be observed that hazardous affect zones for the selected

credible failure scenario shall be extended beyond the B/L’s of the unit, affecting nearby facilities.

Large hole on Bottom Outlet of Stabilizer Reflux Drum: From the incident outcome analysis of the


Fire radiation intensity of 37.5 & 12.5 kW/m2 would spread up to a distance of 78 m & 97 m

respectively. The 5 & 3 psi blast waves may reach up to a distance of 178 m & 189 m.

Based upon the consequence analysis, it can be observed that though selected failure scenario, if

realized, the hazardous affect zones will be spreading throughout the unit & shall also be

extended beyond the B/L’s of the unit affecting nearby population & buildings, irrespective of the

location of the equipment in the unit.

Instrument Tapping Failure at Stabilizer Overhead Pumps: From the event outcome of the


The Jet Fire radiation intensity of 37.5 & 12.5 kW/m2 shall travel a distance of 45 m & 53 m

respectively. The 5 & 3 psi blast waves may reach up to a distance of 63 m & 68 m respectively.


extended beyond the B/L’s of the unit, depending upon the prevailing weather conditions at the

time of release.

Flange Leakage at VB Naphtha Cooler: From the consequence results and graphs it can be

concluded that LFL may travel up to a distance of 45 m. The Jet Fire Radiation of intensity 37.5 &

12.5 kW/m2 may reach up to a distance of 23 m & 29 m respectively. The 5 & 3 psi blast wave

can extend up to a distance of 50 m & 54 m respectively.

Based on the above results it is observed that affect zone for this event may extend beyond the

B/L’s of the unit and may cause damage to the facilities.

6.6.3 VPS


Large Hole on Bottom Outlet of SP VGO Stripper: From the incident outcome analysis of the


Fire Radiation Intensity of 37.5 & 12.5 kW/m2 may travel up to a distance of 12 m & 14 m

respectively. The Pool Fire Radiation Intensity of 37.5 kW/m2 may not be realized & 12.5 kW/m2

may travel up to a distance of 18 m.



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Based upon the consequence analysis, it can be observed that selected failure scenario, if

realized the hazardous affect zones might be restricted with in the unit depending upon the

equipment location.

Instrument Tapping Failure at SP VGO Pump: From the consequence analysis results for this

failure scenario it is realized that LFL shall travel up to a distance of 46 m. The Jet Fire Radiation

Intensity of 37.5 & 12.5 kW/m2 may reach up to a distance of 39 m & 49 m respectively. The 5 & 3

psi blast wave may travel up to a distance of 46 m & 49 m respectively.

Based on the above results it is observed that hazardous affect zone for this event may extend

beyond the B/L’s of the unit and may cause damage to the nearby facilities.

6.6.4 OFFSITES

6.6.4.1 Tank on Fire NOTE: Refer Figures 6.6.4.1.1 in Annexure-III

Diesel (Tank-1) on Fire: From the consequence results and graphs of the selected credible

scenario, it can be concluded that Pool Fire radiation intensity of 8 kW/m2 may affect the adjacent

Tank-1 and Tank-4. The Pool Fire radiation intensity of 32 kW/m2 is not realized in this case.

6.6.4.2 2” Leak at Tank Manifold NOTE: Refer Figures 6.6.4.2.1 to 6.6.4.2.3 in Annexure-III

2 inch Leak at Tank-1: From the incident outcome analysis of the selected failure scenario it is

observed that LFL may be travelling up to a distance of 63 m. The Jet Fire radiation intensity of 32

& 8 kW/m2 would extend up to a distance of 17 m & 23 m respectively. The Pool Fire radiation

intensity of 32 kW/m2 is not realized and 8 kW/m2 would extend up to a distance of 83 m. The 5 &

3 psi blast overpressures travel up to a distance of 89 m & 100 m respectively.

2 inch Leak at Tank-2: From the consequence analysis of the selected failure scenario it is

observed that LFL may spread up to a distance of 95 m. The Jet Fire radiation intensity of 32 & 8

kW/m2 would extend up to a distance of 47 m & 61 m respectively. The Pool Fire radiation


3 psi blast overpressures travel up to a distance of 136 m & 152 m respectively depending upon

the location of leak & prevailing wind conditions at the time of release.

2 inch Leak at Tank-6: From the consequence modeling results of the selected failure scenario it

is observed that LFL may be travelling up to a distance of 63 m. The Jet Fire radiation intensity of

32 & 8 kW/m2 would extend up to a distance of 17 m & 23 m respectively. The Pool Fire radiation


3 psi blast overpressures travel up to a distance of 89 m & 100 m respectively depending upon

the location of leak & prevailing wind conditions at the time of release.

6.6.4.3 Refinery Offsite Pump NOTE: Refer Figures 6.6.4.3.1 to 6.6.4.3.3 in Annexure-III



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Instrument Tapping Failure at Diesel Feed Pump: From the event outcome of the selected failure

scenario it can be observed that LFL may be extended up to a distance of 54 m, can cover the

tank dyke partially present on the plant western side of the pump house and project ware house

present on the plant eastern side. The Jet Fire Radiation Intensity of 32 & 8 kW/m2 can extend up

to a distance of 41 m & 56 m respectively & may damage the Tank-1, Tank-4, Tank-5 and project

warehouse. The 5 & 3 psi blast wave may reach up to a distance of 52 m & 57 m respectively and

may affect the Tank-1, Tank-4, Tank-5 and project warehouse area. The Pool Fire radiation

intensity of 32 kW/m2 is not realized and 8 kW/m2 would extend up to a distance of 51 m and may

engulf the Tank-1, Tank-4, Tank-5 and project warehouse area.

Instrument Tapping Failure at Diesel Blending Feed Pump: From the consequence results and

graphs of the selected failure scenario it can be observed that LFL may be extended up to a

distance of 48 m can reach to the Tank-7 dyke, Tank-6 dyke and Tank-1406/1407/1408 dyke

partially. The Jet Fire Radiation Intensity of 32 & 8 kW/m2 can extend up to a distance of 37 m &

51 m respectively and may cause damage to the Tank-7, Tank-6 and Tank-1405/1406/1407/1408.

The Pool Fire Radiation Intensity of 32 kW/m2 is not realized & 8 kW/m2 can extend up to a

distance of 61 m and can engulf the Tank-6 dyke, Tank-7 dyke, Tank-1405/06/07/08/09/10/11.

These radiations can also affect the MSS-9. The 5 & 3 psi blast wave may reach up to a distance

of 52 m & 56 m respectively and can affect the Tank-6, Tank-7 and Tank-1405/06/07/08/09/10/11.

These waves can also damage the MSS-9.

Instrument Tapping Failure at HGU Feed Pump: From the consequence analysis of the selected

failure scenario it is observed that LFL may spread up to a distance of 99 m and can reach up to

the Tank-2 covering tank dyke present on the plant western side. Flash fire can also reach up to

SEU-II, PFU-II and tanks present on the plant eastern side of the pump house. The Jet Fire

radiation intensity of 32 & 8 kW/m2 would extend up to a distance of 46 m & 59 m respectively and

may cause damage to the tanks present on the plant eastern and western side of the pump

house. The 5 & 3 psi blast overpressures can travel up to a distance of 118 m & 128 m

respectively and can cause damage to the above mentioned facilities including satellite rack

room, operator building present on the plant southern side of the pump house.

6.6.4.4 PRU Offsite & Gantry NOTE: Refer Figures 6.6.4.4.1 to 6.6.4.4.4 in Annexure-III

Propylene Inlet line to Mounded Bullets - 50 mm Leak: From the event outcome of the selected


Fire Radiation Intensity of 32 & 8 kW/m2 can extend up to a distance of 90 m & 117 m

respectively. The 5 & 3 psi blast wave may reach up to a distance of 78 m & 85 m respectively.

Instrument Tapping Failure at Propylene Product Loading Pumps (61-P-201 A/B/C): From the

consequence results and graphs of the selected failure scenario it can be observed that LFL may

be extended up to a distance of 42 m. The Jet Fire Radiation Intensity of 32 & 8 kW/m2 can



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extend up to a distance of 44 m & 55 m respectively. The 5 & 3 psi blast wave may reach up to a

distance of 50 m & 54 m respectively.

Propylene Loading Arm Rupture: From the consequence analysis of the selected failure scenario

it is observed that LFL may spread up to a distance of 81 m. The Jet Fire radiation intensity of 32

& 8 kW/m2 would extend up to a distance of 55 m & 70 m respectively. The 5 & 3 psi blast

overpressures can travel up to a distance of 113 m & 126 m respectively.

Propylene Gantry – 20 mm Leak: From the consequence results and graphs of the selected

credible scenario, it can be concluded that LFL may be extended up to a distance of 39 m. The

Jet Fire radiation intensity of 32 & 8 kW/m2 would spread up to a distance of 42 m & 52 m

respectively. The 5 & 3 psi blast overpressures may travel up to a distance of 39 m & 42 m

respectively.

6.6.4.5 GTG NOTE: Refer Figures 6.6.4.5.1 to 6.6.4.5.4 in Annexure-III

Instrument Tapping Failure at Naphtha Feed Pump to GTG: From the consequence results and

graphs of the selected credible scenario, it can be concluded that LFL may be extended up to a

distance of 97 m. The Jet Fire radiation intensity of 32 & 8 kW/m2 would spread up to a distance

of 45 m & 58 m respectively. The 5 & 3 psi blast overpressures may travel up to a distance of 117

m & 127 m respectively.

2 inch Leak at Naphtha Tank: From the incident outcome analysis of the selected failure scenario

it is observed that LFL may be travelling up to a distance of 99 m. The Jet Fire radiation intensity

of 32 & 8 kW/m2 would extend up to a distance of 50 m & 65 m respectively. The Pool Fire

radiation intensity of 32 kW/m2 is not realized and 8 kW/m2 would extend up to a distance of 45 m.

The 5 & 3 psi blast overpressures travel up to a distance of 133 m & 149 m respectively.

Instrument Tapping Failure at RLNG Skid: From the event outcome of the selected failure


radiation intensity of 32 & 8 kW/m2 shall travel a distance of 16 m & 21 m respectively. The 5 & 3

psi blast waves may reach up to a distance of 13 m & 14 m respectively.

Naphtha Supply line to GTG-20 mm leak: From the consequence analysis of the selected failure

scenario it is observed that LFL may be travelling up to a distance of 91 m. The Jet Fire radiation

intensity of 32 & 8 kW/m2 would extend up to a distance of 43 m & 56 m respectively. The 5 & 3

psi blast overpressures travel up to a distance of 116 m & 126 m respectively.

6.6.5 PRU

NOTE: Refer Figures 6.6.5.1 to 6.6.5.9 in Annexure- III

Large Hole on Bottom Outlet of Feed Surge Drum (V-01): From the consequence analysis of

selected failure scenario it can be observed that LFL shall be travelling up to a distance of 135 m.

The Jet Fire radiation intensity of 37.5 & 12.5 kW/m2 would extend up to a distance of 74 m & 92



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m respectively. The Pool Fire radiation intensity of 37.5 kW/m2 & 12.5 kW/m2 shall not be realized.

The 5 & 3 psi blast overpressures travel up to a distance of 155 m & 164 m respectively.

Based upon the hazard distances it may be observed that hazardous affect zones for the selected

failure scenario shall be extended beyond the B/L’s of the unit and may cause damage to the

nearby facilities.

Instrument Tapping Failure at Propylene Unit Feed Pumps (P-101 A/B): From the event outcome

of the selected failure scenario it can be observed that LFL may be extended up to a distance of

51 m. The Jet Fire radiation intensity of 37.5 & 12.5 kW/m2 would be getting extended up to 45 m

& 53 m respectively. The Pool Fire radiation intensity of 37.5 kW/m2 & 12.5 kW/m2 shall not be

realized. The 5 & 3 psi blast waves may reach up to a distance of 62 m & 66 m respectively.



Large Hole on Bottom Outlet of Debutanizer Column Bottoms (C-101): From the consequence

results and graphs of the selected scenario, it can be concluded that LFL may be extended up to

a distance of 110 m. The Jet Fire radiation intensity of 37.5 & 12.5 kW/m2 would spread up to a

distance of 89 m & 106 m respectively. The 5 & 3 psi blast overpressures travel up to a distance

of 134 m & 143 m respectively.

By analyzing the above results, it can be observed that hazardous affect zones for the selected

credible failure scenario shall be spreading throughout the unit and also extended beyond the

B/L’s of the unit, affecting nearby facilities.

Large Hole on Bottom Outlet of Debutanizer Reflux Drum (V-102): From the event outcome of the


The Jet Fire radiation intensity of 37.5 & 12.5 kW/m2 would be getting extended up to 77 m & 94

m respectively. The Pool Fire radiation intensity of 37.5 kW/m2 & 12.5 kW/m2 shall not be realized.

The 5 & 3 psi blast waves may reach up to a distance of 143 m & 152 m respectively.



Instrument Tapping Failure at De-ethanizer Feed Pump (P-103 A/B): From the incident outcome

analysis of the selected failure scenario it is observed that LFL hazard distance is extended up to

49 m. The Jet Fire radiation intensity of 37.5 & 12.5 kW/m2 would extend up to a distance of 48 m

& 57 m respectively. The 5 & 3 psi blast waves may reach up to a distance of 51 m & 55 m.

From the above consequence results, it can be observed that hazardous affect zones for the

selected credible failure scenario shall be spreading throughout the unit and also extended

beyond the B/L’s of the unit, affecting nearby facilities.

Large hole on Bottom Outlet of De-ethanizer Column (C-102): From the consequence analysis of

the selected failure scenario it is observed that LFL hazard distance is extended up to a distance



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of 119 m. The Jet Fire Radiation Intensity of 37.5 & 12.5 kW/m2 can extend up to a distance of

101 m & 120 m respectively. The 5 & 3 psi blast wave may spread up to a distance of 136 m and

145 m respectively.

Based upon the consequence analysis modeling and by analyzing results, it can be observed that

hazardous affect zones will be spreading throughout the unit & shall also be extended beyond the

B/L’s of the unit affecting nearby facilities.

Large hole on Bottom Outlet of C3/C3= Splitter Bottom (C-103): From the consequence results

and graphs of the selected credible scenario, it can be concluded that LFL may be extended up to

a distance of 111 m. The Jet Fire radiation intensity of 37.5 & 12.5 kW/m2 would spread up to a

distance of 92 m & 109 m respectively. The 5 & 3 psi blast overpressures may travel up to a

distance of 134 m & 143 m respectively.

Based upon the above discussion it may be observed that hazardous affect zones for the selected

credible failure scenario shall be extended beyond the B/L’s of the unit, affecting nearby facilities.

Large hole on Bottom Outlet of C3/C3= Splitter Reflux Drum (V-104): From the incident outcome

analysis of the selected failure scenario it is observed that LFL hazard distance is extended up to

118 m. The Jet Fire radiation intensity of 37.5 & 12.5 kW/m2 would spread up to a distance of 94

m & 111 m respectively. The 5 & 3 psi blast waves may reach up to a distance of 135 m & 144 m.

Based upon the consequence analysis, it can be observed that though selected failure scenario, if

realized, the hazardous affect zones will be spreading throughout the unit & shall also be

extended beyond the B/L’s of the unit affecting nearby facilities.

Flange Leakage at Propylene Product Pump (P-106 A/B): From the event outcome of the selected


Fire radiation intensity of 37.5 & 12.5 kW/m2 shall travel a distance of 23 m & 28 m respectively.

The 5 & 3 psi blast waves may reach up to a distance of 14 m & 15 m respectively.



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7 DETAILED ANALYSIS & RECOMMENDATIONS The detailed consequence analysis of release of hydrocarbon in case of major credible scenarios

are modeled in terms of release rate, dispersion, flammability and toxic characteristics, which

have been discussed in detail in the report. The detailed analysis and recommendations arising

out of the Rapid Risk analysis study for units under Refinery Expansion Project are summarized

below and are based on findings as reported in Section - 6:

Units under Revamp / Modifications APS Unit

Consequence modeling of low frequency failure scenarios for APS unit is carried out and it is

observed that in the event of realization of failure scenarios (Large Hole on bottom outlet of

11-T-2A (M), 11-T-3A (M), 11-D-6 (N) (M), 11-T-4 (M) and Catastrophic Rupture of 11-D-

2001, 11-D-1), radiation & explosion effect zones may get extended beyond the units battery

limits and may affect nearby VPS unit, FRE-VPS unit, FRE-APS unit, FCCU, Combination

unit, Propane block, Naphtha Pump House, CBFS loading facilities, Storage Tanks (TK-

101/102/103) and DIDC Control Room, depending upon the prevalent weather condition and

presence of ignition source at the time of release.

Since, these are low frequency credible failure scenarios, outcomes of the above to be

utilized for updation of the existing Disaster Management Plan (DMP) & Emergency

Response Plan (ERP). Adequate number of hydrocarbon detectors to be ensured at strategic

locations within the APS unit for early leak detection and inventory isolation.

High frequency credible failure scenarios are also modeled for APS unit and their explosion &

radiation effects are analyzed. It is observed that, in the event of the realization of Instrument

tapping failure at 11-P-1 A/B/C/D, 11-P-2002 A/B, 11-P-2 A/B/C/D DIDC control room and

APS operator cabin may get affected by 5 & 3 psi blast overpressures depending upon the

prevalent weather condition and presence of ignition source at the time of release. The

storage tanks (TK-101/102/103) may also get affected by 5 & 3 psi blast waves on account of

close proximity with APS unit, leading to possible domino effects.

DIDC control room & APS Operator Cabin are under direct affect zone of 5 & 3 psi blast

waves of above mentioned high frequency credible failure scenarios.

Since, DIDC Control room is already of blast resistant construction, risk to personnel may be

acceptable. However, it is recommended to shift APS Operator cabin at safe location or

alternatively, it may be merged with the DIDC control room.

The active fire protection system provided for storage tanks (TK-101/102/103) is to be

regularly checked and these scenarios to be included in the existing Disaster Management

Plan (DMP) & Emergency Response Plan (ERP) of the refinery.



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NHT/CCR Low frequency credible failure scenarios for NHT/CCR units are modeled and it is observed

that for large hole on bottom outlet of Separator, Stripper, Stabilizer Receiver and

catastrophic rupture of Feed Surge Drum, Stripper Receiver, Re-contact Drum, radiation &

explosion effect zones may get extended beyond the units battery limits & may affect nearby

new fire station, satellite rack room, administrative building & its annex buildings, depending

upon the prevalent weather condition and presence of ignition source at the time of release.

Administrative & its Annex buildings are under affect zones of various low frequency credible

failure scenarios. Adequate number of hydrocarbon detectors to be ensured at strategic

locations within the NHT/CCR unit for early leak detection and inventory isolation.

Additionally, outcomes of these scenarios to be included in the updation of the existing

Disaster Management Plan (DMP) & Emergency Response Plan (ERP).

In the event of high frequency failure scenario for NHT/CCR Instrument Tapping Failure at

Separator Pumps and Feed Charge Pump, 5 & 3 psi blast overpressure waves may affect the

Administration building depending upon the prevalent weather condition and presence of

ignition source at the time of release. Toluene IDLH concentration in event of Instrument

Tapping Failure at Separator Pumps may have its effect up to a distance of 242 m on grade

level in the prevalent downwind direction and may affect Fire station, administrative building &

its annex buildings, new admin building, workshop.

Depending upon the prevalent wind & weather conditions at the time of release,

Administrative building & its Annex buildings and Workshop may get affected by explosion &

toxic outcomes of above mentioned of high frequency credible failure scenarios in NHT/CCR.

It is recommended to ensure hydrocarbon & toxic gas detectors at appropriate locations

within the unit and detailed mitigating procedures are available as a part of the Disaster

Management Plan & Emergency response plan.

Prime-G Both high & low frequency scenarios are modeled for Prime-G unit and it is observed that for

low frequency failure scenarios (large hole on the bottom outlet of SHU Feed Surge Drum,

Separator Drum, Stabilizer bottom and catastrophic rupture of Splitter Reflux Drum, Stabilizer

Reflux Drum) radiation & explosion affect zones may extend beyond the unit battery limits

and affect the Annex-I building, Annex-II building, Workshop, Office building & Administration

building, depending upon the prevalent weather condition and presence of ignition source at

the time of release.

It is recommended to utilize the outcomes of above scenarios for updation of the existing

Disaster Management Plan (DMP) & Emergency Response Plan (ERP).

Ensure adequate number of hydrocarbon detectors at suitable locations within unit for early

leak detection and inventory isolation.



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NHDT/ISOM Low frequency credible failure scenarios for NHDT/ISOM units are modeled and it is

observed that in the event of large hole on bottom outlet of Separator Drum, Stripper Bottom,

Hydrogenation Reactor Flash Drum, Stabilizer, Deisohexanizer Reflux Drum, LPG Splitter

Reflux Drum and catastrophic rupture of Feed Surge Drum, Isomerization Feed Surge Drum,

Stabilizer Reflux Drum, radiation & explosion effect zones may get extended beyond the units

battery limits & affect nearby facilities including new fire station, administrative building, its

annexe buildings, depending upon the prevalent weather condition and presence of ignition

source at the time of release.

It is recommended to include the outcomes of these low frequency failure scenarios for

updation of the existing Disaster Management Plan (DMP) & Emergency Response Plan

(ERP).

Ensure sufficient number of hydrocarbon detectors within the NHDT/ISOM unit for early leak

detection and inventory isolation.

High frequency credible failure scenarios for NHDT/ISOM are also modeled. In the event of

instrument tapping failure at Feed Pump, Aromatics Hydrogenation Pump, 5 & 3 psi blast

overpressure waves may affect the New Fire station bays & store depending upon the

prevalent weather condition and presence of ignition source at the time of release.

As Fire tender bays and store of Fire & Safety Building are under direct affect zone of the

high frequency credible failure scenarios of NHDT/ISOM unit. It is recommended to relocate

the affected fire tender bays to a safe place.

Also, it is recommended to add an auxiliary fire station at safe location, to cater post

expansion fire & safety requirements.

DHT

Low frequency credible failure scenarios for DHT unit are modeled and it is observed for large

hole on bottom outlet failure scenario of Feed Surge Drum, Stripper Receiver and

catastrophic rupture of Separator, Product Fractionator Receiver, radiation & explosion effect

zones may get extended beyond the unit battery limits & may affect southern proposed HGU

unit, northern SRU/ARU/SWS, western boiler plant, eastern storage tank TK-111 and other

facilities, depending upon the prevalent weather condition and presence of ignition source at

the time of release.

It is recommended to utilize outcomes of these low frequency failure scenarios for updation of

the existing Disaster Management Plan (DMP) & Emergency Response Plan (ERP). Ensure

adequate number of hydrocarbon detectors at suitable locations within the DHT unit for early

leak detection and inventory isolation.

In event of high frequency failure scenario in DHT instrument tapping failure at Charge

Pumps storage tank TK-111 located on east side of the unit may get affected by the 5 psi



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blast overpressure, depending upon the prevalent weather condition and presence of ignition

source at the time of release.

It is recommended to minimize the traffic on road between DHT and dyke containing Tanks

(TK-110/111/112/113) and ensure adequate number of hydrocarbon detectors at suitable

locations within the unit for early leak detection and inventory isolation. Fire protection system

provided for storage tanks (TK-111) to be regularly checked and this scenario to be included

in the existing Disaster Management Plan (DMP) & Emergency Response Plan (ERP) of the

refinery.

New Proposed Process Units HGU

Both high & low frequency flammable scenarios are modeled for new Hydrogen Generation

Unit (HGU). It is observed that the consequence outcomes (radiation & explosion) for the

Naphtha & LPG handling section of the unit may cross the unit’s battery limit and affect the

nearby storage tanks in adjacent dykes and may lead to possible domino effects as all nearby

storage tanks are Class-A. However, actual tanks affected may be ascertained after

finalization of the unit layout.

Hence, it is recommended to locate Naphtha & LPG handling section of the HGU towards

northern side (DHT side) in the proposed plot. However, affected tankage if any, needs to be

either relocated or the service of the tanks to be changed to Class-C/B service, to downscale

the hazard.

Also, these scenarios are to be included for updation of the existing Disaster Management

Plan (DMP) & Emergency Response Plan (ERP).

VBU

Credible high & low frequency scenarios are modeled for VBU and their explosion & radiation

effects are studied. It is observed that consequence outcomes (radiation & explosion) for the

Fractionator overhead & stabilizer section of the unit shall cross the unit’s B/L and may affect

the storage tanks in nearby dykes.

Hence, it is recommended to locate Fractionator overhead & stabilizer section of the VBU

towards eastern side in the proposed plot. Moreover, outcomes of these scenarios to be also

used for updation of the existing Disaster Management Plan (DMP) & Emergency Response

Plan (ERP). Hydrocarbon detectors to be placed at suitable locations within the unit.

VPS

Credible scenario for the VPS unit are modeled and it is observed that Radiation & Explosion

effect zones may be limited to the units B/L’s, depending upon the location of the equipment

in the unit.

Hence, it is recommended to locate the hydrocarbon & fire detectors at suitable locations

within the unit.



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PRU

Consequence modelling is carried out for credible high & low frequency failure scenarios in

PRU. It is observed that affect zone may extend beyond the unit’s B/L & affect the storage

tanks in nearby dyke, depending upon the location of the release, ignition source

encountered and prevalent weather conditions at the time of release.

It is recommended to locate ethanizer section of PRU preferably towards northern side of the

proposed plot.

GTG

Credible failure scenarios of 20 mm hole is modeled at Naphtha Feed to GTG Pump and

Naphtha/ RLNG supply line to GTG. It is observed that Radiation & Explosion affect zone

may cover nearby Naphtha Tanks & existing CPP control room respectively based on the

location of release and weather conditions encountered at the time of release.

It is recommended to install hydrocarbon detectors at the Naphtha Pump house, with

adequate active/ passive fire protection measures and it is recommended to ensure

immediate inventory isolation in the event of any leakage scenario and prepare disaster

management plan & emergency response plan for the same.

OFFSITES

Flammable failure scenario is modeled for the Diesel Tank (Tank on Fire) in the Offsite and it

is observed that the 8 Kw/m2 Pool Fire radiation intensity may affect the nearby Diesel Tank,

leading to possible failure of the tank.

Hence, it is recommended to provide necessary active fire protection for the Diesel Tanks

and adjacent VGO Feed Tanks. This scenario to be also utilized for updation of existing

Disaster Management Plan (DMP) & Emergency Response Plan (ERP) of the refinery.

Flammable failure scenario is modeled for the Diesel Feed Pump (Instrument Tapping

Failure) in the Offsite and it is observed that the 8 Kw/m2 Pool Fire radiation intensity and 8 &

32 Kw/m2 Jet Fire radiation intensity may affect the project ware house.

It is recommended to shift the project ware house from its present location.

It is also suggested to relocate 2 nos. of Tank-6 (Diesel back blending stream tank), since

these tanks are in close vicinity of existing LPG Mounded Bullet pumps.

Failure scenario (Instrument Tapping Failure) for the Propylene Product Loading Pump in the

Offsite is modeled and it is observed that the 32 & 8 Kw/m2 Jet fire radiation intensity may

affect nearby Tank-6 (Diesel back blending stream tank).

Since Tank-6 (Diesel back blending stream tanks, 2 nos.) are in close proximity of Propylene

loading pumps, It is recommended to relocate these tanks to safe location.

Propylene Loading arm rupture and 20 mm leak credible failure scenarios are also modeled

in the Propylene Loading Gantry. It is observed that existing truck parking & LPG Bottling

plant may get affected because of radiation & explosion effect zones of these scenarios. HT



Doc No: A858-17-43-RA-0001 Rev. No.: 0

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line near Truck parking area may be a potential source of ignition in event of any leakage in

the gantry.

Existing LPG bottling plant & truck parking area in the close proximity of loading gantry are

not advisable from safety perspective. Large number of people are expected in the Truck

parking area which may result in fatalities in the event of this failure scenario. So, it is

recommended not to allow any truck parking beneath HT wire and also in LFL zone (~ 85 m

from the edge of the Propylene Loading Gantry).

Further, in order to reduce possible risk to people in existing LPG bottling facility & Truck

parking area, it is recommended to provide excess flow check valves & shut-down valves in

the gantry to restrict the quantity of release in the event of above mentioned failure scenario.

Also, it is recommended to provide hydrocarbon detectors near loading arms with hooters &

automatic water sprinkler system. Safe evacuation plan in the event of any leakage in the

Propylene Gantry & LPG bottling plant needs to be developed & shall be included in the

emergency response plan.

It is suggested to evaluate the risk to the personnel through quantified risk analysis at the

time of detailed engineering.

a) Recommendations for Construction Safety during execution of the Refinery Expansion Project Adequate barricading of the proposed units / revamp units to be done from existing

running process units during construction phase. Hydrocarbon / toxic detectors to be

placed along the barricading suitably to detect any hydrocarbon / toxic gas in vicinity of

construction area.

Also, adequate firefighting & toxic gas handling arrangement are to be ensured in the

construction area. Ensure training of persons associated with construction activities for

response during fire & toxic gas release.

Proper material movement path within the Refinery shall be identified during the

construction phase of the project.

Detailed HSE Plan & HSE Philosophy to be developed by contractors during construction

phase of the project, in line with client’s safety requirements.

It is suggested to carry out HAZID, SIMOPS studies during pre-execution phase of the

Refinery Expansion project to get a detailed overview of the possible hazards during

construction phase and action plan to prevent / mitigate the same.

b) General Recommendations No new Operator Cabin to be located inside battery limits of proposed process units under

Refinery Expansion project. If unavoidable, detailed risk quantification is to be performed

prior to fixing the location of the same.

It is recommended to ensure that adequate firefighting measures are available in truck

parking area of the Propylene Truck loading Terminal.



Doc No: A858-17-43-RA-0001 Rev. No.: 0

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Proper checking of contract people for smoking or inflammable materials to be ensured at

entry gates to avoid presence of any unidentified source of ignition.

Ensure vehicles entering the Refinery are fitted with spark arrestors, as a mandatory item.

In order to prevent secondary incident arising from any failure scenario, it is recommended

that sprinklers and other protective devices provided on the tanks are regularly checked to

ensure these are functional.

Mock drills to be organized at organization level to ensure preparation of the personnel’s

working in Refinery for handling any hazardous situation.

For positively pressurized building, both Hydrocarbon & Toxic detectors need to be placed

at suction duct of HVAC. HVAC to be tripped automatically in event of the detection of any

Hydrocarbon / toxic material by detector.

It is recommended for usage of safer oxidizing agents (Chlorine free) in Cooling Water

circuit, instead of native Cl2.

c) Mitigating Measures Mitigating measures are those measures in place to minimize the loss of containment event and,

hazards arising out of Loss of containment. These include:

Early detection of an undesirable event (HC leak, Toxic gas leak, Flame etc.) and

development of subsequent quick isolation mechanism for major inventories.

Measures for controlling / minimization of Ignition sources inside the Refinery complex.

Active and Passive Fire Protection for critical equipment’s and major structures

Effective Emergency Response plans to be in place

d) Ignition Control Ignition control will reduce the likelihood of fire events. This is the key for reducing the risk

within facilities processing flammable materials. As part of mitigation measure it strongly

recommended to consider minimization of the traffic movement within the Refinery.

e) Escape Routes Ensure sufficient escape routes from the site are available to allow redundancy in escape

from all areas.

Ensure sufficient number of windsocks throughout the site to ensure visibility from all

locations. This will enable people to escape upwind or crosswind from flammable / toxic

releases.

Provide sign boards marking emergency/safe roads to be taken during any exigencies.

f) Preventive Maintenance for Critical Equipment’s In order to reduce the failure frequency of critical equipment’s, the following are

recommended:

a. High head pumps and Compressors, which are in flammable / toxic services, are

needed to be identified.



Doc No: A858-17-43-RA-0001 Rev. No.: 0

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i. Their seals, instruments and accessories are to be monitored closely

ii. A detailed preventive maintenance plan to be prepared and followed.

b. Surge Drums & Reflux drums and high inventory vessels whose rupture may lead

to massive consequences are needed to be identified and following to be ensured:

i. Monitoring of vessel internals during shut down.

ii. A detailed preventive maintenance plan to be prepared and followed.

g) Others Ensure removal of hammer blinds from the process facilities, if any.

Closed sampling system to be considered for pressurized services like LPG, Propylene

etc.

Recommended to use portable HC detector during sampling and maintenance etc.

Provide breathing apparatus at strategic locations inside Refinery.



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8 GLOSSARY CASUALTY Someone who suffers serious injury or worse i.e. including fatal

injuries. As a rough guide fatalities are likely to be half the total

casualties. But this may vary depending on the nature of the event.

HAZARD A chemical or physical condition with the potential of causing

damage.

FLAMMABILITY LIMITS In fuel-air systems, a range of compositions exists inside which a

(UFL – LFL) flame will propagate substantial distance from an

ignition source. The limiting fuel concentrations are termed as

Upper flammability or explosives limit (Fuel concentrations

exceeding this are too rich) and Lower flammability or explosives

limit (Fuel concentrations below this are too lean).

FLASH FIRE The burning of a vapor cloud at very low flame propagation speed.

Combustion products are generated at a rate low enough for

expansion to take place easily without significant overpressure

ahead or behind the flame front. The hazard is therefore only due to

thermal effects.

OVERPRESSURE Maximum pressure above atmosphere pressure experiences during

the passage of a blast wave from an explosion expressed in this

report as pounds per square inch (psi).

EXPLOSION A rapid release of energy, which causes a pressure discontinuity or

shock wave moving away from the source. An explosion can be

produced by detonation of a high explosive or by the rapid burning

of a flammable gas cloud. The resulting overpressure is sufficient to

cause damage inside and outside the cloud as the shock wave

propagation into the atmosphere beyond the cloud. Some authors

use the term deflagration for this type of explosion

DOMINO EFFECT The effect that loss of containment of one installation leads to loss

of containment of other installations

EVENT TREE A logic diagram of success and failure combinations of events used

to identify accident sequences leading to all possible consequences

of a given initiating event.

TLV “Threshold limit value” is defined as the concentration of the

substance in air that can be breathed for five consecutive 8 hours

work day (40 hours work week) by most people without side effect.

STEL “Short Term Exposure Limit” is the maximum permissible average

exposure for the time period specified (15 minutes).



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IDLH “Immediate Dangerous to Life and Health” is the maximum

concentration level from which one could escape within 30 minutes

without any escape impairing symptoms.

PASQUILL CLASS Classification to qualify the stability of the atmosphere, indicated by

a letter ranging from A, for very unstable, to F, for stable.

FREQUENCY The number of times an outcome is expected to occur in a given

period of time.



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9 REFERENCES 1. Classification of hazardous locations, A. W. Cox, F. P. Lees and M. L. Ang, Published by

the Institute of Chemical engineers, U. K.

2. The reference manual, Volume-II, Creemer & Warner Ltd. U. K. (Presently Entec).

3. Risk analysis of six potentially hazardous industrial objects in the Rijnmond area; A pilot

study. A report to the Rijnmond Public Authority. D. Riedel publishing company, U. K.

4. Loss prevention in the process industries, Hazard identification, Assessment and Control,

Frank. P. Lees (Vol. I, II & III), Published by Butterworth-Heinemann, U. K.

5. AICHE, CCPS, Chemical process Quantitative Risk Analysis

6. Guideline for Quantitative Risk assessment, ‘Purple book’.



Doc No: A858-17-43-RA-0001 Rev. No.: 0

Page 1 of 11


ANNEXURE-I CONSEQUENCE ANALYSIS HAZARD DISTANCES

(EXISTING & PROPOSED UNITS)

Temp.

(OC)

Press.

(Kg/cm2g)4 KW/m2 12.5 KW/m2 37.5 KW/m2 4 KW/m2 12.5 KW/m2 37.5 KW/m2 2 psi 3 psi 5 psi

2F 58 83 62 50 82 53 NR 78 71 65 -

3D 69 80 59 47 84 61 NR 88 81 75 -

5D 77 74 54 42 83 69 56 99 92 86 -

2F 39 - - - - - - 185 146 114 -

3D 43 - - - - - - 185 146 114 -

5D 61 - - - - - - 185 149 119 -

2F 93 69 53 44 51 28 21 132 121 113 -

3D 74 67 51 41 54 31 22 97 90 85 -

5D 59 63 47 38 55 34 22 73 67 62 -

2F 26 83 62 50 94 51 NR 35 31 28 -

3D 25 77 57 45 102 54 NR 35 32 28 -

5D 24 71 52 41 110 56 NR 37 33 29 -

2F 138 108 82 67 67 33 NR 192 177 164 -

3D 114 104 78 62 72 34 NR 154 143 134 -

5D 91 99 73 57 78 35 NR 129 119 111 -

2F 136 110 83 67 65 34 NR 212 191 174 -

3D 116 105 78 62 70 36 NR 162 149 138 -

5D 92 99 73 57 75 38 NR 133 122 113 -

2F 278 - - - 138 63 NR 429 389 357 -

3D 244 - - - 149 62 NR 367 332 304 -

5D 227 - - - 166 63 NR 333 302 279 -

2F 82 67 52 43 56 30 NR 119 109 101 -

3D 67 65 49 40 59 32 NR 83 78 73 -

5D 54 61 46 36 62 35 NR 71 66 61 -

2F 124 128 100 83 - - - 171 158 148 -

3D 123 123 94 77 - - - 165 154 144 -

5D 133 118 88 71 - - - 174 163 154 -

2F 20 35 28 23 - - - 17 15 14 -

3D 18 34 26 22 - - - 17 15 14 -

5D 15 32 25 20 - - - 17 15 14 -

2F 109 124 96 79 - - - 144 133 124 -

3D 106 120 91 74 - - - 140 130 122 -

5D 110 110 82 66 - - - 150 140 132 -

2F 18 24 19 15 - - - 17 15 14 -

3D 12 23 18 14 - - - 16 15 13 -

5D 9 22 17 13 - - - - - - -

HPCL Mumbai- Existing Units Consequence Analysis Hazard Distances

11-T-4 (M) Large Hole on bottom outlet 157.4 9.4

2.2

19.7

0.8

-

Leak Rate

Kg/s

1.9

Flash Fire

(m)

IDLH Conc

Distance

(m)

Operating Conditions

18.8

39.4

6.4

2186.8

46 8.4 35.6

Failure Case

11-P-1 A/B/C/D 36.5

11-T-2A (M)

NOTEWeather

-

6.8

Large Hole on bottom outlet

Jet Fire (m) Pool Fire (m)

32.9

176

Instrument Tapping Failure

Blast Over Pressure (m)

14.9

30 24.1

Catastrophic Rupture




138

Unit

11-D-2001 42.32 2.109

11-P-2002 A/B 42.89 10

APS

1

2

3

4

5

11-T-3A (M)

11-T-2001

Sl No.

12

55 1.6

6

Equipment

7 11-D-1

11-P-3 A/B


Instrument Tapping Failure 55.46

13Seal Failure

9 11-D-6 (N)(M) Large Hole on bottom outlet

10 11-P-1023 A/B Flange Leakage 47.6 19.3

8.4

43

8 11-P-2 A/B/C/D

11

Page 2 of 11

Temp.

(OC)

Press.



Leak Rate

Kg/s

Flash Fire

(m)

IDLH Conc

Distance

(m)


Failure Case

11-P-1 A/B/C/D 36.5

NOTEWeather


32.9Instrument Tapping Failure


14.9

Unit

APS

1

Sl No. Equipment

2F 45 - - - - - - 214 170 135 -

3D 47 - - - - - - 217 173 136 -

5D 62 - - - - - - 224 178 140 -

2F 87 84 64 53 - - - 117 107 100 -

3D 81 81 61 49 - - - 111 103 97 -

5D 79 78 57 45 - - - 99 92 86 -

2F 305 178 137 112 - - - 422 391 366 H2S - NR

3D 244 173 130 105 - - - 328 306 288 H2S - NR

5D 206 166 122 96 - - - 279 259 243 H2S - NR

2F 21 19 15 NR - - - 30 28 25 -

3D 20 19 15 NR - - - 29 27 25 -

5D 19 20 16 NR - - - 17 15 14 -

2F 102 125 97 80 - - - 142 131 123 Benzene - 80

3D 99 120 91 75 - - - 128 118 111 Benzene - 77

5D 103 110 82 67 - - - 138 128 121 Benzene - 78

2F 71 - - - - - - 106 96 89 -

3D 79 - - - - - - 110 100 92 -

5D 89 - - - - - - 121 111 103 -

2F 23 38 29 25 - - - 31 28 26 -

3D 20 36 28 23 - - - 30 27 25 -

5D 18 35 26 21 - - - 17 16 14 -

2F 100 83 64 53 - - - 143 132 123 Toluene - 242

3D 89 81 61 49 - - - 112 104 98 Toluene - 206

5D 81 78 57 45 - - - 110 103 97 Toluene - 165

2F 18 16 12 NR - - - 17 15 14 Toluene - NR

3D 17 16 12 NR - - - 17 15 14 Toluene - NR

5D 16 16 13 NR - - - 17 15 14 Toluene - NR

2F 134 - - - 69 36 NR 209 189 173 -

3D 135 - - - 82 45 NR 206 187 171 -

5D 133 - - - 96 55 NR 214 183 167 -

2F 43 37 29 24 - - - 58 54 50 Toluene - 89

3D 31 36 27 22 - - - 43 40 37 Toluene - 80

5D 23 34 25 20 - - - 31 28 26 Toluene - 66

2F 176 144 112 92 - - - 245 226 211 -

3D 175 139 106 86 - - - 231 216 203 -

5D 162 134 99 79 - - - 218 204 192 -

40.512

24 0.5

10 Recontact Drum (102-D-2004) Catastrophic Rupture -15 25.2 -

10.4

Net Gas Compressor 2nd Stage

(102-C-2002 A/B)Instrument Tapping Failure - Toxic

41

1.9Stabilizer Feed/Bottom Exchanger

(102-E-2008)

5 Stripper Bottom (102-T-1001) Large Hole on bottom outlet - Toxic 229 10.54

1

55

10.5

4

38

8

2 Charge Pumps (102-P-1001A/B) Instrument Tapping Failure 100

3

83

105

Separator (102-D-1003) Large Hole on bottom outlet - Toxic 55

Feed Surge Drum (102-D-1001) Catastrophic Rupture

Recycle Compressor

(102-C-1001 A/B)Instrument Tapping Failure 93 34

2 -

21.09

43.6

0.7

13.4

100

63

55 10 -

7Stripper Reflux Pump

(102-P-1003 A/B)Flange Leakage 55 18.5 2.2

6 Stripper Receiver (102-D-1005) Catastrophic Rupture

28 12.9Separator Pumps

(102-P-2001 A/B)Instrument Tapping Failure - Toxic

Flange Leakage - Toxic11

9

Stabilizer Receiver (102-D-2007) Large Hole on bottom outlet

NHT/CCR

Page 3 of 11

Temp.

(OC)

Press.



Leak Rate

Kg/s

Flash Fire

(m)

IDLH Conc

Distance

(m)


Failure Case

11-P-1 A/B/C/D 36.5

NOTEWeather




14.9

Unit

APS

1

Sl No. Equipment

2F 70 71 55 46 - - - 89 82 76 -

3D 63 68 52 42 - - - 84 78 73 -

5D 60 65 49 39 - - - 83 77 73 -

2F 169 123 93 76 62 34 NR 266 239 217 -

3D 145 118 88 71 64 38 29 206 190 176 -

5D 116 111 82 65 60 43 28 165 151 140 -

2F 88 81 62 51 - - - 117 108 100 -

3D 82 78 59 48 - - - 110 103 97 -

5D 78 76 56 44 - - - 99 92 86 -

2F 54 62 48 40 - - - 73 67 62 -

3D 46 60 45 37 - - - 59 55 51 -

5D 45 57 43 34 - - - 58 54 50 -

2F 176 - - - 59 25 NR 270 245 224 -

3D 183 - - - 64 26 NR 269 245 227 -

5D 173 - - - 71 29 NR 253 230 212 -

2F 285 168 128 104 209 144 101 401 371 346 -

3D 239 163 122 97 NR NR NR 321 298 280 -

5D 194 156 114 89 NR NR NR 269 249 233 -

2F 17 NR NR NR - - - 16 14 13 H2S - NR

3D 17 NR NR NR - - - 16 14 13 H2S - NR

5D 16 NR NR NR - - - 15 14 13 H2S - NR

2F 41 44 34 28 - - - 58 53 50 -

3D 33 43 32 26 - - - 44 41 38 -

5D 30 41 30 24 - - - 32 29 27 -

2F 106 107 82 68 - - - 143 132 124 -

3D 104 104 78 63 - - - 138 129 121 -

5D 109 98 72 57 - - - 138 128 120 -

2F 16 30 23 19 - - - 17 15 14 -

3D 14 29 22 18 - - - 17 15 14 -

5D 12 28 21 17 - - - 16 15 13 -

2F 71 - - - 40 17 9 111 101 92 -

3D 83 - - - 43 20 9 118 108 100 -

5D 78 - - - 45 24 10 111 101 92 -

2F 156 - - - 63 24 NR 241 218 199 -

3D 164 - - - 69 25 NR 241 221 204 -

5D 155 - - - 77 26 NR 225 204 189 -

PRIME G

3 -1 Feed Surge Drum (103-D-1001) 70

6Separator Drum Overhead

(105-D-1003)Instrument Tapping Failure - Toxic 40 15 0.34

10Stabilizer Reflux Drum

(105-D-1005)Catastrophic Rupture 55 3 -

Flange Leakage 40 32 3.3

Stabilizer Bottoms (105-T-1003)8 3.8Large Hole on bottom outlet

23.6

Large Hole on bottom outlet 40

Instrument Tapping Failure 40

Catastrophic Rupture 55 3

15 56.8

-

18 8.5


Instrument Tapping Failure 12.5

88 10 6.6

100

3Light Gasoline Pumps

(105-P-1004 A/B)

Large Hole on bottom outletSHU Feed Surge Drum

(105-D-1001)100 3

2SHU Feed Pumps

(105-P-1001 A/B)33.1

1

NHDT/ISOM


13

5

Stabilizer Overhead Pumps

(102-P-2003 A/B)

7 Quench Pumps (105-P-1005 A/B)

Separator Drum (105-D-1003)

4Splitter Reflux Drum

(105-D-1002)

NHT/CCR

25.7

9Stabilizer Bottom Pumps

(105-P-1007 A/B)Flange Leakage 178 10.5 1.7

178

Page 4 of 11

Temp.

(OC)

Press.



Leak Rate

Kg/s

Flash Fire

(m)

IDLH Conc

Distance

(m)


Failure Case

11-P-1 A/B/C/D 36.5

NOTEWeather




14.9

Unit

APS

1

Sl No. Equipment

2F 99 79 61 50 - - - 131 121 112 -

3D 87 77 58 47 - - - 111 103 97 -

5D 77 74 54 43 - - - 99 92 86 -

2F 313 177 135 111 - - - 440 408 381 H2S - NR

3D 243 171 128 103 - - - 329 307 289 H2S - NR

5D 202 164 121 95 - - - 279 259 243 H2S - NR

2F 106 129 99 82 - - - 143 132 123 Benzene-83

3D 102 123 94 77 - - - 140 130 121 Benzene-79

5D 106 112 85 68 - - - 139 129 121 Benzene-81

2F 29 39 31 26 - - - 32 29 27 -

3D 24 38 29 24 - - - 31 28 26 -

5D 20 36 27 22 - - - 30 27 25 -

2F 168 - - - 79 32 NR 253 230 211 -

3D 174 - - - 86 32 NR 254 233 215 -

5D 163 - - - 96 33 NR 238 216 200 -

2F 95 87 67 55 - - - 130 120 112 -

3D 88 84 64 52 - - - 112 104 97 -

5D 85 80 60 48 - - - 110 103 97 -

2F 22 20 15 NR - - - 30 28 26 -

3D 20 20 16 NR - - - 29 27 25 -

5D 19 20 17 NR - - - 17 15 14 -

2F 128 141 109 90 - - - 171 159 148 -

3D 126 136 103 84 - - - 167 155 146 -

5D 134 126 94 75 - - - 177 165 155 -

2F 10 24 19 15 - - - 15 14 13 -

3D 9 23 17 14 - - - - - - -

5D 8 22 16 13 - - - - - - -

2F 98 128 99 82 - - - 130 120 112 -

3D 95 123 94 77 - - - 127 118 110 -

5D 98 112 84 68 - - - 127 118 110 -

2F 54 - - - - - - 148 118 94 -

3D 66 - - - - - - 152 121 96 -

5D 98 - - - - - - 156 132 121 -

2F 49 63 49 41 - - - 61 55 51 -

3D 45 61 47 38 - - - 59 54 50 -

5D 44 58 44 35 - - - 58 54 50 -

Stabilizer Reflux Drum

(103-D-2005)


Catastrophic Rupture 60

9Hydrogenation Reactor Flash Drum (103-D-

2004)Large Hole on bottom outlet 135 16

Isomerization Reactor Feed Pumps (103-P-

2004 A/B)Seal Failure 135 33 1.05

12

13Stabilizer Reflux Pump

(103-P-2005 A/B)

5

Aromatics Hydrogenation Pump

(103-P-2001 A/B)

Stabilizer Bottom (103-T-2001)

H2 Make-up Compressor

(103-C-2001 A/B)

6Isomerization Feed Surge Drum (103-D-

2001)


60 18

Stripper Reflux Pump

(103-P-1004 A/B)

10

11

0.8

51

109 36.9

2 Feed Pumps (103-P-1001 A/B) 70 25 11.2

19 60.5

Flange Leakage 40 18 2.2

Instrument Tapping Failure 40 13.7

40 2.5 -

18

13.6 46.4


4 Stripper Bottom (103-T-1001) Large Hole on bottom outlet-TOXIC 170

NHDT/ISOM

3 Separator Drum (103-D-1003) Large Hole on bottom outlet-TOXIC

8

40

-13.6

8.3

Large Hole on bottom outlet 180 14.3 46.8


7

Page 5 of 11

Temp.

(OC)

Press.



Leak Rate

Kg/s

Flash Fire

(m)

IDLH Conc

Distance

(m)


Failure Case

11-P-1 A/B/C/D 36.5

NOTEWeather




14.9

Unit

APS

1

Sl No. Equipment

2F 142 105 81 66 64 33 NR 213 195 180 -

3D 115 101 76 62 69 34 NR 154 143 134 -

5D 93 96 71 57 74 36 NR 128 119 111 -

2F 88 72 56 46 49 35 25 115 106 99 -

3D 74 69 53 43 44 36 27 97 90 84 -

5D 62 66 49 39 34 31 27 85 78 73 -

2F 17 26 20 17 12 12 12 17 15 14 -

3D 13 25 19 15 - - - 16 15 13 -

5D 10 24 18 14 - - - - - - -

2F 15 33 25 21 - - - 17 15 14 -

3D 13 31 24 20 - - - 16 15 13 -

5D 12 30 22 18 - - - 16 15 13 -

2F 117 131 103 87 - - - 157 145 135 -

3D 115 126 97 80 - - - 153 142 133 -

5D 122 120 91 74 - - - 162 152 143 -

2F 16 32 26 22 - - - 17 15 14 -

3D 15 31 24 20 - - - 16 15 14 -

5D 13 29 22 18 - - - 16 15 13 -

2F 55 69 54 46 - - - 73 67 63 -

3D 50 66 51 42 - - - 71 66 61 -

5D 50 63 48 39 - - - 59 55 51 -

2F 97 107 81 65 79 38 NR 140 127 117 -

3D 84 104 77 61 84 39 NR 113 104 98 -

5D 68 98 72 56 91 39 NR 88 81 75 -

2F 83 90 68 56 - - - 115 106 99 -

3D 79 84 63 51 - - - 101 93 87 -

5D 80 77 57 46 - - - 101 93 87 -

2F 306 - - - - - - 469 426 392 -

3D 317 - - - - - - 471 430 397 -

5D 323 - - - - - - 470 429 397 -

2F 30 27 18 NR - - - 33 29 27 H2S-NR

3D 28 27 19 NR - - - 32 29 26 H2S-NR

5D 24 28 20 NR - - - 31 28 26 H2S-NR

2F 30 29 22 16 - - - 34 31 28

3D 27 30 23 18 - - - 33 30 27

5D 26 30 25 21 - - - 33 30 27

DHT

0.85

41.7

2.24

Charge Pumps (700-P-1001 A/B) 111 99 24

109 1.76 20.1

19.1



18LPG Splitter Reflux Drum

(103-D-2009)

3 Separator (700-D-1003) Catastrophic Rupture

15Isomerate Storage Pumps

(103-P-2009 A/B)55 14

14Deisohexanizer Reflux Drum

(103-D-2006)Large Hole on bottom outlet 55 1.5

2

20LPG Product Pump

(103-P-2012 A/B)Instrument Tapping Failure 21.340

40

5

55 66.3 -

4 Separator Overhead (700-D-1003) Instrument Tapping Failure- Toxic

1 Feed Surge Drum (700-D-1002)

9.2

66.3

92 77 1.3

Large Hole on bottom outlet 40 12.9

17LPG Splitter Bottom Pump

(103-P-2013 A/B)Flange Leakage

5

Recycle Gas Compressor

(700-C-1001)Instrument Tapping Failure

19LPG Splitter Reflux Pump

(103-P-2011 A/B)17.4 1.94

16.3

8

176 19.4

NHDT/ISOM

16Separator Drum Bottom Pump

(103-P-201 A/B)Seal Failure

Flange Leakage


55 1.24

Page 6 of 11

Temp.

(OC)

Press.



Leak Rate

Kg/s

Flash Fire

(m)

IDLH Conc

Distance

(m)


Failure Case

11-P-1 A/B/C/D 36.5

NOTEWeather




14.9

Unit

APS

1

Sl No. Equipment

2F 28 27 21 14 - - - 34 31 28

3D 25 28 22 16 - - - 33 30 27

5D 24 28 24 20 - - - 33 30 27

2F 241 151 116 94 178 117 75 355 326 302 H2S-549

3D 190 146 110 88 174 116 78 255 236 221 H2S-454

5D 153 140 103 81 169 116 82 214 198 185 H2S-375

2F 37 44 34 28 - - - 46 42 39 H2S-172

3D 30 42 32 26 - - - 32 29 27 H2S-151

5D 27 40 30 24 - - - 32 29 26 H2S-129

2F 10 18 13 NR - - - - - -

3D 9 17 14 NR - - - - - -

5D 7 17 16 NR - - - - - -

2F 72 - - - - - - 256 205 162

3D 76 - - - - - - 259 206 163

5D 120 - - - - - - 264 213 175

2F 33 42 33 27 44 32 22 45 41 38

3D 27 41 31 25 43 34 24 32 29 27

5D 24 39 29 23 39 33 26 31 29 26

2F 59 61 46 38 35 29 24 75 69 63

3D 52 59 44 35 36 31 26 72 66 62

5D 51 57 42 33 37 33 27 71 65 61

2F 39 43 33 28 - - - 46 42 39

3D 31 42 32 26 - - - 44 40 37

5D 27 40 30 24 - - - 32 29 26

DHT

10Product Fractionator Receiver

(700-D-1011)

11Product Fractionator Net Overhead Pumps

(700-D-1011)2.7

Instrument Tapping Failure 198 14 7.2

296 25 0.83

82 65 1

Diesel Product Pumps

(700-P-1005 A/B)Seal Failure

Catastrophic Rupture 88

6Make-up Gas Compressor

(700-C-1002 A/B)Instrument Tapping Failure

7 Stripper Receiver (700-D-1010) Large Hole on bottom outlet-Toxic 37 9 41.3

8Stripper Overhead Pumps

(700-P-1004 A/B)Flange Leakage- Toxic 37 32

0.35 -

13Naphtha Trim Coolers

(700-E-1020 A/B)Flange Leakage 40 25 2.8

3.1

Flange Leakage 88 25

9

12Kerosene Product Pump

(700-P-1009 A/B)

Page 7 of 11

Temp.

(OC)

Press.


2F 22 19 14 NR - - - 30 28 25 -

3D 21 19 15 NR - - - 29 27 25 -

5D 19 19 16 NR - - - 17 15 14 -

2F 186 138 105 86 80 43 NR 290 263 240 -

3D 159 132 100 80 82 44 NR 216 199 186 -

5D 129 125 93 73 85 46 NR 176 162 151 -

2F 38 46 36 30 - - - 46 42 39 -

3D 32 45 34 28 - - - 44 41 38 -

5D 29 43 32 26 - - - 32 29 26 -

2F 130 126 99 82 - - - 173 160 149 -

3D 128 122 93 76 - - - 166 155 145 -

5D 136 117 87 70 - - - 176 164 155 -

2F 73 82 64 53 - - - 100 93 87 -

3D 68 78 60 50 - - - 86 80 74 -

5D 68 75 56 45 - - - 85 79 74 -

2F 207 131 99 80 - - - 328 296 270 -

3D 171 127 94 75 - - - 247 228 212 -

5D 136 121 88 69 - - - 192 177 164 -

2F 107 74 56 46 41 31 22 142 132 123 -

3D 87 71 53 43 39 32 23 111 103 97 -

5D 73 69 50 39 37 31 24 98 91 85 -

2F 145 141 110 91 - - - 200 185 172 -

3D 145 135 104 85 - - - 192 179 168 -

5D 156 130 97 78 - - - 202 189 178 -

2F 57 68 53 45 - - - 74 68 63 -

3D 51 65 50 41 - - - 71 66 61 -

5D 50 63 47 38 - - - 70 65 61 -

2F 45 37 29 23 - - - 59 54 50 -

3D 33 36 27 22 - - - 43 40 37 -

5D 25 34 25 20 - - - 31 28 26 -

2F 8 18 14 12 35 18 NR - - - -

3D 8 21 16 14 36 19 NR - - - -

5D 6 22 17 14 37 22 NR - - - -

2F 46 65 49 39 - - - 52 49 46 -

3D 46 63 46 37 - - - 51 48 46 -

5D 45 60 44 34 - - - 50 47 45 -

2F 126 133 104 87 - - - 171 158 148 -

PRU

1 Feed surge Drum (V-01) Large Hole on bottom outlet 40.9 10.7 40.4

HPCL Mumbai- New Units Consequence Analysis Hazard Distances

Unit Sl No. Equipment Failure Case

Operating ConditionsLeak Rate

Kg/sWeather

Flash Fire

(m)

Jet Fire (m) Pool Fire (m) Blast Over Pressure (m) IDLH Conc

Distance

(m)

NOTE

21 9.9

HGU

5 LPG Feed Pump Instrument Tapping Failure 40 40 12.75

1 H2 Circulation Compressor Instrument Tapping Failure 67 31.3 0.67

Naphtha Pump Flange Leakage 40 3.5

2 Naphtha Surge Drum Large Hole on bottom outlet 40 4.5 29.6

3

Large Hole on bottom outlet 40 5

4 LPG Surge Drum Large Hole on bottom outlet 40 7

39.7

32.86

1 Main Fractionator Reflux Drum

42.1

4 Stabilizer Overhead Pumps Instrument Tapping Failure 40 18.7 8.6

3 Stabilizer Reflux Drum Large Hole on bottom outlet 40 11.5

5 VB Naphtha Cooler Flange Leakage 40

VBU

30.2

2 Fractionator Overhead Pumps Instrument Tapping Failure 40

SP VGO Pump Instrument Tapping Failure 210 10 7.4

VPS

1 SP VGO Stripper Large Hole on bottom outlet 210 -0.993 1.5

2

10.5 1.9

Page 8 of 11

Temp.

(OC)

Press.


HPCL Mumbai- New Units Consequence Analysis Hazard Distances



Kg/sWeather

Flash Fire

(m)

Jet Fire (m) Pool Fire (m) Blast Over Pressure (m) IDLH Conc

Distance

(m)

NOTE

HGU

1 H2 Circulation Compressor Instrument Tapping Failure 67 31.3 0.67

3D 125 128 98 81 - - - 166 154 145 -

5D 135 122 92 74 - - - 175 164 155 -

2F 51 67 53 45 - - - 72 66 62 -

3D 47 64 50 41 - - - 59 54 50 -

5D 46 61 47 38 - - - 59 54 50 -

2F 110 136 106 89 - - - 154 143 134 -

3D 106 130 100 83 - - - 141 130 122 -

5D 110 124 94 76 - - - 150 140 132 -

2F 119 136 107 90 - - - 157 145 135 -

3D 117 130 101 84 - - - 153 142 133 -

5D 122 124 94 77 - - - 163 152 143 -

2F 49 71 57 48 - - - 61 55 51 -

3D 47 68 53 45 - - - 59 54 50 -

5D 47 65 49 41 - - - 59 54 50 -

2F 119 151 120 101 - - - 157 145 136 -

3D 114 144 113 94 - - - 153 143 134 -

5D 118 137 105 86 - - - 153 142 133 -

2F 111 139 109 92 - - - 155 143 134 -

3D 107 133 103 85 - - - 141 131 122 -

5D 111 127 96 78 - - - 151 141 132 -

2F 118 139 111 94 - - - 156 144 135 -

3D 115 133 104 87 - - - 153 142 133 -

5D 119 126 96 79 - - - 152 141 133 -

2F 17 34 28 23 - - - 17 15 14 -

3D 15 33 26 22 - - - 16 15 14 -

5D 14 31 24 20 - - - 16 15 13 -

PRU

1 Feed surge Drum (V-01) Large Hole on bottom outlet 40.9 10.7 40.4

2Propylene Unit Feed Pumps

(P-101 A/B)Instrument Tapping Failure 40.9 20.92 9.04

3Debutanizer Column Bottoms

(C-101)Large Hole on bottom outlet 93.2 16 48.7

4Debutanizer Reflux Drum

(V-102)Large Hole on bottom outlet 44 15 46.5

5De-ethnizer feed Pump

(P-103 A/B)Instrument Tapping Failure 44 36.69 11.6

6 De-ethanizer Column (C-102) Large Hole on bottom outlet 85 33.7 70.8

7C3/C3= Splitter Bottom

(C-103)Large Hole on bottom outlet 79.1 20.4 53.3

8C3/C3= Splitter reflux Drum

(V-104)Large Hole on bottom outlet 46.9 18.5 51.8

9Propylene Product Pump

(P-106 A/B)Flange Leakage 47 25.19 2.4

Page 9 of 11

Temp.

(OC)

Press.

(Kg/cm2g)4 KW/m2 8 KW/m2 32 KW/m2 4 KW/m2 8 KW/m2 32 KW/m2 2 psi 3 psi 5 psi

2F - - - - 48 27 NR - - -

3D - - - - 52 30 NR - - -

5D - - - - 56 33 NR - - -

2F 63 27 23 17 136 83 NR 111 100 89

3D 37 27 22 17 142 85 NR 49 45 41

5D 25 26 21 16 153 91 NR 31 28 26

2F 95 72 61 47 79 46 NR 170 152 136

3D 74 69 59 44 82 46 NR 115 105 96

5D 52 67 56 42 89 48 NR 79 72 66

2F 63 27 23 17 136 83 NR 111 100 89

3D 37 27 22 17 142 85 NR 49 45 41

5D 25 26 21 16 153 91 NR 31 28 26

2F 47 70 58 44 72 51 NR 61 57 52

3D 54 68 56 41 77 58 NR 72 67 63

5D 54 65 53 38 81 64 NR 73 68 63

2F 42 68 56 42 70 49 NR 60 56 52

3D 48 66 54 40 75 55 NR 60 56 51

5D 48 63 51 37 79 61 NR 61 56 52

2F 99 70 59 46 - - - 139 128 118

3D 79 67 56 42 - - - 101 94 87

5D 63 64 53 39 - - - 86 80 75

2F 69 137 117 90 - - - 93 85 78

3D 64 130 111 83 - - - 92 84 77

5D 59 124 104 76 - - - 79 72 66

2F 42 64 55 44 - - - 58 54 50

3D 40 61 52 41 - - - 57 53 49

5D 39 58 49 37 - - - 46 42 38

2F 81 81 70 55 - - - 141 126 113

3D 73 76 65 51 - - - 110 100 92

5D 59 70 60 46 - - - 82 74 67

2F 39 60 52 42 - - - 46 42 39

3D 37 57 49 39 - - - 45 41 38

5D 36 55 46 35 - - - 45 41 38

2F 97 69 58 45 - - - 139 127 117

3D 78 66 56 42 - - - 101 93 87

5D 62 63 52 39 - - - 86 79 74

2F 99 76 65 50 78 45 NR 169 149 133

Tank on Fire1 Tank-1 Tank On Fire Amb.

HPCL Mumbai - Offsite Consequence Analysis Hazard Distances



Kg/sWeathers

Flash Fire

(m)

Jet Fire (m) Pool Fire (m) Blast Over Pressure (m)

NOTE

Amb. 0.7 12.1

Amb. 0.8 14.8

-

Amb. 0.8 14.8

Atm.

Amb. 10 7.1

Amb. 12 8.9

Amb. 10 8.1

2" Leak

Offsite Pump

3 HGU Feed Pump Instrument Tapping Failure

1 Diesel Feed Pump Instrument Tapping Failure

2 Tank-2 2" Leak in Manifold

Tank-6 2" Leak in Manifold3

2 Diesel Blending Pump Instrument Tapping Failure

1 Tank-1 2" Leak in Manifold

PRU Offsite &

Gantry

1 Propylene Inlet line to Mounded Bullets 50 mm Leak 40

3 Propylene Loading Arm Rupture Amb.

Saturation

Pressure49.8

2Propylene Product Loading Pumps

(61-P-201 A/B/C)Instrument Tapping Failure Amb. 21.7 9

Amb

Saturation

Pressure7

4 Propylene Gantry 20 mm Leak Amb.Saturation

Pressure7.9

GTG

9 6.7

2 Naphtha Tank (T-263) 2 inch Leak Amb Atm 12

1 Naphtha Feed Pump to GTG Instrument Tapping Failure

Page 10 of 11

Temp.

(OC)

Press.

(Kg/cm2g)4 KW/m2 8 KW/m2 32 KW/m2 4 KW/m2 8 KW/m2 32 KW/m2 2 psi 3 psi 5 psi

Tank on Fire1 Tank-1 Tank On Fire Amb.

HPCL Mumbai - Offsite Consequence Analysis Hazard Distances



Kg/sWeathers

Flash Fire

(m)

Jet Fire (m) Pool Fire (m) Blast Over Pressure (m)

NOTE

-Atm.

3D 77 74 62 47 81 46 NR 115 104 94

5D 55 71 59 44 88 48 NR 79 72 66

2F 12 24 21 16 - - - 16 14 13

3D 11 24 21 17 - - - 15 14 13

5D 10 24 22 17 - - - 15 14 13

2F 91 66 56 43 - - - 139 126 116

3D 74 63 53 40 - - - 100 92 86

5D 58 60 50 37 - - - 74 68 63

3 RLNG Skid Instrument Tapping Failure Amb

4 Naphtha Supply Line to GTG 20 mm Leak Amb. 7 5.9

GTG

40 2

2 Naphtha Tank (T-263) 2 inch Leak Amb Atm 12

Page 11 of 11

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