HAZARDS ASSOCIATED WITH FLAMAMBLE … · 1.1 project description ... 6.5.1.6 resid hydrocracking unit ... 7.1 list of last major refinery incidents globally in last 10 years

RAPID RISK ANALYSIS STUDY OF

PROPOSED RESIDUE UPGRADATION

PROJECT AT MATHURA, UTTAR PRADESH

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

PREFACE

Engineers India Limited (EIL), New Delhi, has been entrusted by M/s IOCL to carry out the EIA and

Rapid Risk Analysis of the facilities (New and Revamp) coming under Residue Up-Gradation and

Distillate yield Improvement Project with 11 MMTPA Crude Processing at Mathura Refinery. As a part

of the project RRA is being carried out for the subject job.

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

consequences, of all likely incidents, 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

SECTION-1 ................................................................................................................................................................. 6

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

1.1 PROJECT DESCRIPTION ....................................................................................................... 6

1.2 CONCLUSIONS AND RECOMMENDATION .......................................................................... 6

SECTION-2 ............................................................................................................................................................... 12

INTRODUCTION ..................................................................................................................................................... 12

2.1 STUDY AIMS AND OBJECTIVE ........................................................................................... 12

2.2 SCOPE OF WORK ................................................................................................................ 12

2.3 PROCESS DESCRIPTION .................................................................................................... 13

2.3.1 RESID HYDROCRACKER UNIT (REHU) .............................................................................. 13

2.3.2 OTHERS UNIT ....................................................................................................................... 14

SECTION-3 ............................................................................................................................................................... 15

SITE CONDITION ................................................................................................................................................... 15

3.1 GENERAL ............................................................................................................................. 15

3.2 SITE, LOCATION AND VICINITY .......................................................................................... 15

METEOROLOGICAL CONDITIONS ...................................................................................... 15

SECTION-4 ............................................................................................................................................................... 18

HAZARDS ASSOCIATED WITH THE PROJECT ............................................................................................... 18

4.1 GENERAL ............................................................................................................................. 18

4.2 HAZARDS ASSOCIATED WITH FLAMAMBLE MATERIALS .............................................. 18

4.2.1 HYDROGEN .......................................................................................................................... 18

4.2.2 NAPHTHA AND OTHER HEAVIER HYDROCARBONS ....................................................... 18

4.3 HAZARDS ASSOCIATED WITH TOXIC/CARCINOGENIC MATERIALS ............................. 19

4.3.1 HYDROGEN SULPHIDE ....................................................................................................... 19

4.3.2 CHLORINE ............................................................................................................................ 19

SECTION-5 ............................................................................................................................................................... 21

HAZARD IDENTIFICATION ................................................................................................................................. 21

5.1 GENERAL ............................................................................................................................. 21




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5.2 MODES OF FAILURE ........................................................................................................... 21

5.3 SELECTED FAILURE CASES .............................................................................................. 22

SECTION-6 ............................................................................................................................................................... 24

CONSEQUENCE ANALYSIS ................................................................................................................................. 24

6.1 GENERAL ............................................................................................................................. 24

6.2 CONSEQUENCE ANALYSIS MODELLING .......................................................................... 24

6.2.1 DISCHARGE RATE ............................................................................................................... 24

6.2.2 DISPERSION ......................................................................................................................... 24

6.2.3 FLASH FIRE .......................................................................................................................... 24

6.2.4 JET FIRE ............................................................................................................................... 25

6.2.5 POOL FIRE ........................................................................................................................... 25

6.2.6 VAPOR CLOUD EXPLOSION ............................................................................................... 25

6.2.7 TOXIC RELEASE .................................................................................................................. 25

6.3 SIZE AND DURATION OF RELEASE ................................................................................... 25

6.4 DAMAGE CRITERIA ............................................................................................................. 26

6.4.1 LFL OR FLASH FIRE ............................................................................................................ 26

6.4.2 THERMAL HAZARD DUE TO POOL FIRE, JET FIRE AND FIRE BALL .............................. 26

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

6.4.4 TOXIC HAZARD .................................................................................................................... 27

6.5 CONSEQUENCE ANALYSIS OF THE SELECTED FAILURE CASES ................................. 27

6.5.1 NEW PROPOSED UNITS ...................................................................................................... 27

6.5.1.1 NAPHTHA SPLITTER UNIT (NSU) ....................................................................................... 27

6.5.1.2 VACUUM DISTILLATION UNIT (VDU) .................................................................................. 28

6.5.1.3 HYDROGEN GENERATION UNIT (HGU) ............................................................................. 28

6.5.1.4 SULPHUR RECOVERY UNIT (SRU) ..................................................................................... 29

6.5.1.5 ONCE THROUGH HYDROCRACKER (OHCU) .................................................................... 29

6.5.1.6 RESID HYDROCRACKING UNIT .......................................................................................... 30

6.5.1.7 OFFSITES ............................................................................................................................. 31

6.5.1.8 COOLING TOWER (CT) ........................................................................................................ 31




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6.5.2 REVAMPED UNITS ............................................................................................................... 31

6.5.2.1 CRUDE DISTILLATION UNIT (CDU) .................................................................................... 31

6.5.2.2 DIESEL HYDROTREATING UNIT (DHDT) ............................................................................ 32

SECTION-7 ............................................................................................................................................................... 34

7.1 LIST OF LAST MAJOR REFINERY INCIDENTS GLOBALLY IN LAST 10 YEARS ............. 34

7.1.1 FIRE AND EXPLOSION AT CHEVRON RICHMOND REFINERY, USA ............................... 34

7.1.2 FIRE AND EXPLOSION AT AMUAY REFINERY, VENEZUELA........................................... 34

7.1.3 TERMINAL FIRE AND EXPLOSION AT JAIPUR (INDIA) .................................................... 34

7.1.4 BUNCEFIELD TANK FARM FIRE AND EXPLOSION, UK .................................................... 34

7.1.5 EXPLOSION AND FIRE AT FORMOSA PLASTICS, ILLINOIS, USA ................................... 35

7.1.6 EXPLOSION AND FIRE AT BP TEXAS REFINERY, USA .................................................... 35

SECTION-8 ............................................................................................................................................................... 36

CONCLUSIONS AND RECOMMENDATIONS .................................................................................................... 36

GLOSSARY ............................................................................................................................................................... 43

REFERENCES ......................................................................................................................................................... 45

ANNEXURE-I: CONSEQUENCE ANALYSIS HAZARD DISTANCES

ANNEXURE-II: FIGURES FOR CONSEQUENCE ANALYSIS

ANNEXURE-III: OVER ALL PLOT PLAN




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SECTION-1

EXECUTIVE SUMMARY

1.1 PROJECT DESCRIPTION

Engineers India Limited (EIL), New Delhi, has been entrusted by M/s IOCL to carry out the EIA and

Rapid Risk Analysis of the facilities (New and Revamp) coming under Residue Up-gradation and

Distillate Yield Improvement Project with 11.0 MMTPA Crude Processing at Mathura Refinery. As a part

of the project RRA is being carried out for the subject job.

This report contains observations, results and recommendations of Rapid Risk analysis study of New

and Revamp Units considered under proposed residue Upgradation project. The study evaluates

consequences from the different potential accident scenarios considered for the units and associated

off-site facilities. Subsequently, analyses the extent of damage due to such incidents and draws suitable

mitigating measures.

1.2 CONCLUSIONS AND RECOMMENDATION

The major conclusions and recommendations arising out of the Rapid Risk analysis study for the IOCL

Mathura Refinery are summarized below. This is based on the detail analysis given in Sections – 6.

NEW PROPOSED UNITS

NSU: Large Hole in Bottom line of Naphtha Splitter Ovhd. Separator: It can be observed from

consequence analysis of this failure scenario that LFL shall approach to the Refinery Compound wall on

south side and also extends into New HGU & OHCU. The Jet Fire Radiation Intensity of 37.5 & 12.5

Kw/m2 shall be affecting equipments in NSU as well as in OHCU. The 5 & 3 psi blast wave shall spread

throughout OHCU and covering majority of equipments in New HGU, moreover it shall also be crossing

Refinery Compound wall on southern side and engulfing the total truck parking & even extending

beyond it. The 12.5 & 4 Kw/m2 Radiation intensity on account of Pool Fire shall be limited to vicinity of

the unit.

As LFL shall be reaching up to the South Side Compound wall of the Refinery and 5 & 3 psi blast wave

shall be affecting Truck parking area, it is recommended to consider relocation of the Truck Parking

Area.

VDU: Vacuum Diesel Product/IR Pump Instrument Tapping Failure: From the Consequence

analysis of this failure scenario it can be observed that the LFL shall be crossing the unit’s B/L on

western side. The 37.5 & 12.5 Kw/m2 Radiation intensity on account of Jet Fire shall be extended

beyond the unit but will not be affecting any nearby unit or tankages. The 5 & 3 psi blast wave shall be

spreading throughout the unit damaging all the equipments and extending up to Tank No.: 951, 952,

953 and 954.

The affected tankage should be provided with suitable fire fighting measures. In order to prevent

secondary incident arising from this failure, it is recommended that fire monitors and hydrant provided




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around the tanks to be regularly checked to ensure that they are functional. Less hazardous equipments

(typically RCO pumps, hot oil system etc.) to be located on western side block of CDU.

SRU: Instrument Tapping Failure in Acid Gas K.O Drum-(TOXIC): From the consequence graph of

this failure scenario it can be observed that H2S IDLH concentration shall be extended upto existing

MSQ Unit, SRU Unit, New ETP Unit and MSQ-CR & its Substation, LPG Sphere area Operator cabin,

affecting personnel’s present in these buildings. Moreover the H2S IDLH concentration may cross the

Refinery Compound wall on western side and affecting the population beyond compound wall, if

present.

As H2S IDLH concentration shall be extended up to existing MSQ Unit, SRU Unit, any Temporary

Operator Cabin present in these units is to be removed / relocated. As MSQ-CR & its Substation are

positively pressurized, hence personnel in these building shall not be affected by H2S IDLH

concentration. Either relocation or positive pressurization of LPG Sphere area Operator cabin near LPG

MCC room is recommended. Moreover, H2S detectors are to be installed at strategic locations. DMP &

ERP should include instructions for Human evacuations from above specified areas on priority, in any

case of leakage of H2S from SRU.

OHCU: Stripper Ovhd Pump Instrument Tapping Failure: From the outcomes of consequence

analysis of this failure scenario it can be observed that LFL shall be extended up to New HGU Unit. The

37.5 & 12.5 Kw/m2 Radiation intensity on account of Jet Fire may damage the equipments in vicinity of

leakage in OHCU and also extends up to nearby New HGU. The 5 & 3 psi blast wave shall be affecting

most of equipments in OHCU, New HGU and NSU. The H2S IDLH concentration shall be affecting

DHDT/DHDS control room, proposed new control room and substation, process cooling water control

room, substation-151/11, offsite utility substation, office building, drinking & fresh water control room,

eco office and may even crosses the Boundary wall on Southern side of the Refinery affecting

individuals present.

DHDT/DHDS control room and proposed ‘new control room & substation’ are positively pressurized;

hence personnel in these building shall not be affected by H2S IDLH concentration.

It is recommended to install H2S detectors with sirens at strategic location in the plant in the event of any

such leakage to alert personnel present in the existing building viz. process cooling water control room,

drinking and fresh water control room, office building and Eco office and evacuation procedures should

be in place to evacuate personnel.

Since H2S IDLH concentration crosses boundary wall on southern side, it is also recommended to install

H2S detectors with sirens on south side of the unit and DMP should address emergency evacuation

procedures in case of any such leakage. Since the truck parking area is located in the south side

outside plant boundary hence it is recommended to consider the relocation of Truck Parking Area.




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OHCU: Product Fractionator Receiver Catastrophic Rupture: From the consequence graphs of this

failure scenario, it can be observed that LFL shall spreading within the unit. The 5 psi blast wave shall

be affecting all the equipments of New OHCU, NSU & HGU and even crosses the Refinery Compound

wall on southern side affecting Truck parking area. The 3 psi blast wave may further propagate and

affects equipments in H2 Plant & HGU Unit.

Though LFL shall be restricted to B/L’s of the Unit, relocation of Truck Parking Area to be looked upon

as it is getting affected by 5 and 3 psi blast wave.

OHCU: Debutanizer Receiver Catastrophic Rupture: From the incident outcome analysis of this

failure scenario, it can be observed that the Flash Fire affect zone shall be limited to vicinity of B/L’s of

unit itself. The 5 & 3 psi blast wave spreads in OHCU unit and also extends into New HGU unit. The H2S

IDLH concentration may extend beyond the unit’s B/L up to New HGU, Sub Officers Residence,

relocated Ware House & Store Shed, New CT’s, Proposed New CR for Slurry Hydrocracker & SHCU

and Existing DHDT Unit, DHDS Unit & their CR, Substation, Existing H2 Bullets, OHCU, H2 Plant, HGU,

Off Building, CT’s, Chemical House. The H2S IDLH concentration may also extends beyond the

Compound wall of Refinery on Southern side and affects population present there.

It is recommended to install H2S detectors with sirens on East & South side B/L of the unit and DMP

should address emergency evacuation procedures in case of any such scenario. The manned building

within the affect zone of H2S IDLH should be evacuated on priority.

RESID HYDROCRACKING UNIT: Fractionator Ovhd. Accumulator Catastrophic Rupture: From

the consequence analysis of this failure scenario it can be observed that LFL shall be spreading beyond

the B/L’s of the unit, extending up to New ETP, New SRU Block, New Control Room, LPG Spheres,

PRU Sphere, Mounded Bullets and may even cross the Compound wall on South side up to Marketing

Division & Truck Parking Area. The 5 & 3 psi blast wave shall be damaging all equipments in the unit &

may even spreads beyond the B/L’s of the unit covering New ETP, New Control Room, New SRU Block,

LPG Spheres, PRU Spheres, Mounded bullets, Fire Water Tank (186-T-01A/B/C), Existing HGU Unit,

Truck parking area, Marketing Division area. The 12.5 Kw/m2 Radiation intensity on account of Pool Fire

affect zone shall be limited to unit itself.

As LFL shall be reaching up to Truck Parking Area and it is also getting affected by 5 & 3 psi blast

wave, it is recommended to consider relocation / removal of Truck Parking Area.

RESID HYDROCRACKING UNIT: Naphtha Product Pump Instrument Tapping Failure: From the

incident outcome analysis of this failure scenario it can be observed that the LFL shall be spreading

throughout the unit and may approach to the New Control room. The 37.5 & 12.5 Kw/m2 Radiation

intensity on account of Jet Fire shall be limited to vicinity of units, mostly producing localized damages.

The 5 & 3 psi blast wave shall be spreading throughout the unit damaging all the equipments in the unit

and affects New Control Room, substation and marketing building.




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As Proposed New Control Room shall be getting affected by 5 & 3 psi blast wave, it is recommended to

be made Blast Proof with Positive Pressurization.

CT: Chlorine Toner Leakage: From the graphs of consequence analysis of this failure scenario, it can

be observed that any leakage from Chlorine Toner shall be going to affect the total area under Mathura

Refinery and even beyond the Compound walls of Refinery.

As Chlorine IDLH is affecting all the individuals inside Mathura Refinery and even beyond its Compound

wall, it is suggested to substitute / replace Chlorine with some other safer alternative viz. ClO2. In

absence of replacement it is recommended to install Cl2 detectors with sirens at strategic locations and

train people for emergency evacuation in case of Cl2 leakage. IOCL should also involve State level

authorities / District Administration in trainings/Mock drills, as Cl2 IDLH affect zone is extended beyond

the Compound Wall of Refinery, population in vicinity of the Refinery are to be informed about ill-effects

of Cl2.

REVAMPED UNITS

CDU: Large Hole in Bottom Line of Atmospheric Column Reflux Drum: From Incident Outcome

Analysis of this failure scenario, it can be observed that Flash Fire affect zone is getting extended

beyond the Unit and extending up to VBU, CRU, Portion of FCC. The 37.5 & 12.5 Kw/m2 Radiation

intensity on account of Jet Fire is spreading up to VBU, producing localized damage. The 5 psi blast

wave is damaging all of the equipments in CDU and affect zone is extended up to VBU, CRU, FCC,

Portion of MSQ, Main CR, CRU Substation, Substation-8, CT’s & Tank nos.: 951, 952, 953, 954, 955,

956. The 3 psi blast wave further propagates & affects Tank nos.: 957, 958, 404, 002 and Fire Water

Tank: 186-T-01A. The 12.5 Kw/m2 Radiation intensity on account of Pool Fire is limited to leakage

source only, mostly producing localized damage.

5 psi blast wave is affecting Main CR which is already of Blast proof construction. The affected tankage

should be provided with suitable fire fighting measures. In order to prevent secondary incident arising

from this failure, it is recommended that fire monitor and hydrant provided around the tanks to be

regularly checked to ensure that they are functional. Proper routine check to be ensured in the area to

prevent presence of any potential ignition source in the vicinity.

CDU: Naphtha Stabilizer Reflux Drum Catastrophic Rupture: From the outcomes of Consequence

Analysis of this failure scenario, it can be observed that LFL is restricted to B/L’s of the Unit. The 5 & 3

psi blast waves are spreading throughout the unit and even beyond B/L’s of the unit majorly affecting

VBU, CRU Main Control Room, CRU Substation, Substation-8 and Tanks No.: 951, 953 and 954.

Ensure the blast proof construction of CRU Main Control Room & its Substation, Substation-8.


secondary incident arising from this failure, it is fire monitor and hydrant provided around the tanks to be

regularly checked to ensure that they are functional.




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DHDT: Large Hole in the HP Cold Separator Bottom: From Consequence graphs of this failure

scenario, it can be observed that LFL is spreading beyond the unit and covering all of the operating

units of the refinery. It also crosses the Refinery compound wall on eastern side. The 37.5 & 12.5 Kw/m2

Radiation intensity on account of Jet Fire is damaging all the equipments within the unit & crossing the

unit’s B/L but is not reaching up to any Unit/ Storage/ Building. The 5 & 3 psi blast wave is affecting all

the Refinery units and affecting storages also. It also crosses the Refinery compound wall on Eastern &

Southern side affecting individuals present over there. H2S IDLH concentration spreads beyond the

B/L’s of the unit and extends up to CRU, FCC, Laboratory, Fire Station, Admin Building , Project

Building, Warehouse, Workshop, Training Hall, Community Hall, New proposed Store Shed, proposed

warehouse, proposed store, proposed CT, proposed New HGU, proposed New OHCU, existing OHCU,

H2 Unit, New HGU, CT’s , Fire water tanks.

Though the Failure Frequency of such an incident is remote, H2S detectors at suitable locations within

the unit shall be ensured. The virtue of extent of damages by this case can be utilized for making an

efficient DMP. The probability of such an incident can be further reduced by efficient monitoring of

vessel internals during shut-down.

GENERAL RECOMMENDATIONS

It is recommended to interchange the locations of new proposed OHCU and HGU in order to

further reduce the hazard beyond the southern side of the compound wall of the refinery.

It is recommended that the HP section and toxic section are to be located towards the north east

side of the unit in equipment layout of Resid Hydrocracking unit on account of close proximity of

LPG and propylene sphere.

In the event of any leakage from existing LPG P/H which may affect adjacent new unit (Resid

Hydrocracking Unit) in case if the release gas finds any ignition source in its path. It is therefore

recommended to restrict the traffic movement on all the roads around the existing sphere area to

avoid the presence of ignition source.

Hydrocarbon detector with alarm shall be provided at strategic location on west side of the

sphere in the event of any leakage from existing LPG P/H which may get ignited because of

ignition source from moving rail wagon. Hence therefore it is recommended to stop the rail

wagon movement immediately on actuation of hydrocarbon detector alarm.

Proper barricading during construction phase of new units of proposed residue Upgradation

project from the existing units to be done.

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.

The vehicles entering the Refinery complex should be fitted with spark arrestors as a mandatory

item.




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In order to prevent secondary incident arising from any failure scenario, it is recommended that

sprinklers and other protective devices provided on the tanks to be regularly checked to ensure

that they are functional.

Emergency security / evacuation drills to be organized at organization level to ensure

preparation of the personnel’s working in IOCL-MR for handling any extreme situation.

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:

Rapid detection of an uncommon event (HC leak, Toxic gas leak, Flame etc) and alarm

arrangements and development of subsequent quick isolation mechanism for major inventory.

Measures for controlling / minimization of Ignition sources inside the Refinery complex.

Active And Passive Fire Protection for critical equipments and major structures

Effective Emergency Response plans to be in place

Detection and isolation

IGNITION CONTROL

Ignition control will reduce the likelihood of fire events. This is the key for reducing the risk within

facilities that process flammable materials. As part of mitigation measure it strongly

recommended to consider minimization of Smoking booths in the Refinery

ESCAPE ROUTES

Ensure windsocks throughout the site to ensure visibility from all locations. This will enable

people to escape upwind or crosswind from flammable / toxic releases. Sufficient escape routes

from the site should be provided to allow redundancy in escape from all areas.

Ensure sign boards marking emergency/safe roads to be taken during any exigencies.

PREVENTIVE MAINTENANCE FOR CRITICAL EQUIPMENTS

In order to further reduce the probability of catastrophes efficient monitoring of vessel internals

during shut-down to be carried out for Surge Drums & Reflux drums and critical vessels whose

rupture would lead to massive consequences.

OTHERS

Closed sampling system to be considered for pressurized services like Propylene etc.

Whenever a person visits for sampling and maintenance etc. in H2S prone area, it is to be

ensured to carry portable H2S detector.

Ensure breathing apparatus at strategic locations inside Refinery.




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SECTION-2

INTRODUCTION

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 to evaluate their extent. Typical hazardous

consequences include Fire, Explosion and Toxic releases.

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 results are useful in developing a meaningful emergency plan and also serve as a powerful training

tool.

The Risk assessment study has been carried out using the risk assessment software program ‘PHAST’

ver. 6.6 developed by DNV Technica.

2.2 SCOPE OF WORK

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

under M-11 Project of IOCL Mathura Refinery. It covers the following facilities of the IOCL-Mathura:

Table 2.2-1: Process Facilities under proposed Residue Upgradation Project of IOCL Mathura Refinery

Complex

SL. NO. UNITS CAPACITY

Crude Capacity (from 8 MMTPA to) 11 MMTPA

1 Resid Hydrocracking Unit 2.3 MMTPA

2 New Hydrocracker unit 2.0 MMTPA

3 Hydrogen Unit 110 TMTPA

4 Sulphur Recovery Unit (SRU) with TGTU 3 x 300 TPD

5 Additional VDU 2.5 MMTPA

6 DHDT revamp 2.4 MMTPA

7 Sour Water Stripper (SWS) 50 TPH

8 Amine Regeneration Unit 600TPH

9 Nitrogen unit 1200 NM3/hr




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Offsite facilities:

HSD Tank

HVGO Tank

DHDT Feed Tank

Mounded bullet

Utilities

Following additional facilities are envisaged in the offsite to cater to the project requirement

S.No. Facility Capacity

1 Gas Turbo Generator (GTG) / Steam Turbine Generator

2x30 MWhr 1x20 MWhr

2 Cooling Tower for Process cooling water 5X2500 m3/hr

3 Air compressor and Drier 2x5000 NM3/hr

4 RO Plant for DM water 1x200 m3/hr

5 RO Plant for ETP effluent 1x250 m3/hr

6 Storage tanks 3x30 TKL 2 X25 TKL

NOTE: For consequence modeling of new proposed units, Compositions, Operating Temperature &

Pressures, Location has been inherited from similar units of IOCL-Panipat Refinery. For revamped units

actual data from the IOCL-Mathura has been used.

2.3 PROCESS DESCRIPTION

Description of the process units mentioned above is furnished below:

2.3.1 RESID HYDROCRACKER UNIT (REHU)

The unit will be designed for processing of vacuum residue. The capacity of the unit will be 2.1 MMTPA.

The Resid Hydrocracking process is a commercially proven technology for conversion and upgrading of

vacuum residue. The process uses the catalytic ebullated-bed reactor. It is most applicable for

exothermic reactions and feedstocks that are difficult to process in a fixed-bed or plug flow reactor. It is a

fluidized-bed three-phase system with back mixing of both the reactor liquid composition and the

catalyst particles. The inherent advantages of a good back-mixed bed are excellent reactor temperature

control and low and constant pressure drop over several years of continuous operation because bed

plugging and channeling are eliminated. The exothermic heat of reaction is efficiently utilized to heat the

reactor feed, increasing heat efficiency and decreasing fuel consumption. The catalyst used in the

ebullated-bed reactor is held in a fluidized state through the upward lift of liquid reactants (feed oil plus

recycle) and gas (hydrogen feed and recycle) which enter the reactor plenum and are distributed across

the bed through a distributor and grid plate. The height of the ebullated catalyst bed is controlled by the

rate of recycle liquid. This liquid recycle rate is adjusted by varying the speed of the ebullating pump

(i.e., a canned centrifugal pump) which varies the flow of ebullating liquid obtained from the internal




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vapor/liquid separator inside the reactor. Operation in this ebullated state results in low reactor pressure

drop and a back-mixed, nearly isothermal bed. Very importantly, fresh catalyst can be added and spent

catalyst withdrawn to control the level of catalyst activity (i.e., desulphurization) in the reactor.

Reactor section is followed by typical fractionation section which is typically similar to a hydrocracker or

hydro-treatment unit. The make and Recycle gas compressor philosophy is also more or less similar.

2.3.2 OTHERS UNIT

Hydrocracker unit shall be designed for 65-70% conversion for treating the VGO generated due to

additional crude processing as well as from the resid hydrocracking unit. Modifications in the existing

Crude distillations will also be required for processing of 11 MMTPA. A new VDU shall be required for

processing additional RCO from additional crude processing. Revamp of existing DHDT is envisaged to

treat the additional diesel generated due to additional crude processing and Resid hydrocracking unit.

Hydrogen unit is required for supplying hydrogen to the RHU, new hydrocracker and additional

requirement due to DHDT revamp. As a part of environmental measures, SRU, SWS, ARU are required

for recovering sulphur.




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SECTION-3

SITE CONDITION

3.1 GENERAL

This chapter depicts the location of IOCL Mathura Refinery complex. It also indicates the meteorological

data, which will be used for the Rapid Risk Analysis study.

3.2 SITE, LOCATION AND VICINITY

The Refinery Complex is situated around 12 KM south of Mathura city. The geographical location of

Mathura is 410 40’ East and 270 23’ North. National Highway No.2 and a broad gauge railway line

connecting Delhi and Agra runs along the north-east perimeter of the Refinery. On the western

perimeter, there is a meter gauge railway line to Agra fort. Mathura Distributary and Farah Distributary

run on the eastern and western side of the complex. Agra is situated 40 kilometer south east of the

complex.

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.

For the present Risk Analysis study, Meteorological data of Agra station (nearest observatory) have

been taken from the Climatological Tables of Observatories in India (1961-1990) published by Indian

Meteorological Department.

ATMOSPHERIC PARAMETERS

The Climatological data that has been used for the Risk Analysis study is summarized below:

Table 3.3-1: Atmospheric Parameters

Sl. No Parameter Average value considered for study

1. Ambient Temperature (OC) 28

2. Atmospheric Pressure (mm Hg) 760

3. Relative Humidity (%) 56

4. Solar Radiation flux (kW/m2) 0.7




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WIND SPEED AND DIRECTION

Based on the Meteorological data provided at the IMD table, it is observed that calm weather can be

experience for 16% of the time in a year. Average wind speed of magnitude of 1 m/s blows for around

74% of the time, in a year. Wind speed of magnitude of 2 m/s blows 26% of the time in a year. Hence

predominant wind speed for Refinery complex at Mathura is 1 m/s.

Table 3.3-2: Average mean wind speed (m/s)

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

0.59 0.83 0.94 1.027 1.16 1.41 1.3 1.05 0.94 0.52 0.41 0.44

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 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 describes 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. Table 3.4-3 indicates the various Pasquill stability

classes.

Table 3.3-3: 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




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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 – 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.

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:

Average wind speed of magnitude of 1 m/s blows for around 74% of the time. In order to realize the

worst hazardous distances, weather stability of “F” was selected with wind speed 1 m/s for consequence

analysis. Wind speed of 1-2 m/s can be realized in the month of Apr to Aug. As a conservative approach

Neutral condition, “D” has been selected with wind speed 2 m/s for risk analysis. Average wind speed of

greater than 2 m/s cannot be realized at this weather station.

Discussions, conclusions and recommendations pertaining to consequence analysis are based on the

worst weather condition. The consequence results are reported in tabular form for all the weather

conditions and are represented graphically for worst weather condition.

Table 3.3-4: Weather conditions

Wind Speed Pasquill Stability

1 F

2 D




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SECTION-4

HAZARDS ASSOCIATED WITH THE PROJECT

4.1 GENERAL

Refinery complex handles a number of hazardous materials like LPG, Hydrogen, Naphtha, Benzene,

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

chemicals like Benzene, Chlorine and Hydrogen sulfide are also being handled in the Refinery. This

chapter describes in brief the hazards associated with these materials.

4.2 HAZARDS ASSOCIATED WITH FLAMAMBLE MATERIALS

4.2.1 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.

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 Table for properties of hydrogen.

Table-4.2-1: Hazardous Properties of Hydrogen

S. NO. PROPERTIES VALUES

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.

4.2.2 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




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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 Table for properties of Naphtha.

Table-4.2-2: Hazardous properties of Naphtha

S. NO. PROPERTIES VALUES

1. LFL (%v/v) 0.8

2. UFL (%v/v) 5.0

3. Auto ignition temperature (°C) 228

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

5. Normal Boiling point (°C) 130 -155

6. Flash point (°C) 38 - 42

4.3 HAZARDS ASSOCIATED WITH TOXIC/CARCINOGENIC 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 Table for

hazardous properties of Hydrogen Sulphide.

Table 4.3-1: Toxic effects of Hydrogen Sulfide

S.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 CHLORINE

Chlorine is required in a refinery complex for water treatment. Chlorine tonner is therefore located near

the Cooling water system. Chlorine gas is not flammable but highly poisonous in nature. Its routes of

entry into the human body are through inhalation, ingestion, skin and eyes. An exposure to chlorine can

cause eye irritation, sneezing, restlessness. Exposure to high concentration of chlorine can cause

respiratory distress and violent coughing. Lethal effects of inhalation depend not only on the

concentration of the gas to which people are exposed, but also on the duration of exposure. The toxic

effects of chlorine are listed in table.

Table 4.3-2: Toxic effects of Chlorine




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S.NO. THRESHOLD LIMITS CONCENTRATION (PPM)

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

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

30 min exposure) 10




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SECTION-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.

“Guillotine-Breakage” of pipe-work.

Small hole, cracks or instrument tapping failure in piping and vessels.

Flange leaks.

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




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Pressure and temperature effects

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. Failure cases have 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, sample connection failure,

instrument tapping failure, drains, vents, etc. The consequence results will provide enough data

for planning routine safety exercises. This will emphasize the area where operator's vigilance is

essential.




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

catastrophic failure of lines, process 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 incidents considering all equipments, units, but the

consequence of a similar incident considered in the list below could be used to foresee the consequence

of that particular accident.

NOTE: Refer Annexure-1 for selected failure cases for facilities of IOCL Mathura Refinery and its

consequence hazard distances.




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SECTION-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 below

Table 6.3: Leak Size for selected failure scenario

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

Large Hole 50 mm, complete rupture of 2” drain line

Catastrophic Failure Complete rupture of pressure vessels




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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 leak.

Ref [5] AICHE, CCPS, Chemical process Quantitative Risk Analysis

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. Table tabulates the damage effect due to thermal radiation intensity.

Table 6.4.2: 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 (1st degree burns)

is likely.

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




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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. Table illustrates the damage effect of blast overpressure.

Table 6.4.3: 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 OF THE SELECTED FAILURE CASES

This section discusses the consequences of selected failure scenario as listed in the previous section.

The consequence analysis hazard distances are reported in tabular form for all weather conditions as

an Annexure-I and are represented graphically in Annexure-II for all selected failure cases in a unit for

worst scenario. Please refer Annexure-I for hazardous distances and Annexure-II for graphical

representation.

6.5.1 NEW PROPOSED UNITS

6.5.1.1 NAPHTHA SPLITTER UNIT (NSU)

Large Hole in Bottom line of Naphtha Splitter Ovhd. Separator: It can be observed from the

consequence analysis (SL. No.1 & figure 6.5.1.1.1 A-D) of this failure scenario that LFL shall approach

to the Refinery Compound wall on south side and also extends into New HGU & OHCU. The Jet Fire




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Radiation Intensity of 37.5 & 12.5 Kw/m2 shall be affecting equipments in NSU as well as in OHCU. The

5 & 3 psi blast wave shall spread throughout OHCU and covering majority of equipments in New HGU,

moreover it shall also be crossing Refinery Compound wall on southern side and engulfing the total

truck parking & even extending beyond it. The 12.5 & 4 Kw/m2 Radiation intensity on account of Pool

Fire shall be limited to vicinity of the unit.

Naphtha Splitter Bottom Pump Instrument Tapping Failure: From outcomes of consequence modeling

(SL. No.2 & figure 6.5.1.1.2 A-D); it can be observed that LFL shall be crossing the Unit’s B/L and may

affect to new OHCU. The 37.5 & 12.5 Kw/m2 Radiation intensity on account of Jet & Pool Fire shall be

restricted with the unit and warranting no cause for concern. The 5 & 3 psi blast wave intensity shall be

affecting the equipments in New OHCU and adjacent new HGU unit.

6.5.1.2 VACUUM DISTILLATION UNIT (VDU)

Vacuum Diesel Product/IR Pump Instrument Tapping Failure: From the Consequence analysis (SL.

No.3 & figure 6.5.1.2.1 A-D) of this failure scenario it can be observed that the LFL shall be crossing the

unit’s B/L on western side. The 37.5 & 12.5 Kw/m2 Radiation intensity on account of Jet Fire shall be

extended beyond the unit but will not be affecting any nearby unit or tankages. The 5 & 3 psi blast wave

shall be spreading throughout the unit damaging all the equipments and extending up to Tank No.: 951,

952, 953 and 954.

In Addition the above case following additional case; Seal Failure of LVGO Product / IR Pump (SL. No.4

& figure 6.5.1.2.2 A-D) was modeled and it was observed that the outcome of consequence analysis

for this failure scenarios shall be limited to vicinity of leakage, mostly producing localized damage and

does not affects any nearby Storage / Unit.

6.5.1.3 HYDROGEN GENERATION UNIT (HGU)

Raw Naphtha Surge Drum Catastrophic Rupture: From the Incident Outcome Analysis (SL. No.5 &

figure 6.5.1.3.1 A-D) of this failure scenario, it can be observed that LFL shall be covering whole of New

HGU & OHCU and will be reaching upto Existing HGU, H2 Unit, H2 Storage Bullets. The 37.5 & 12.5

Kw/m2 Radiation intensity on account of Pool Fire shall be affecting some of the equipments in New

HGU, 12.5 Kw/m2 Radiation intensity may further extends and affects equipments in existing H2 Plant,

part of OHCU. The 5 & 3 psi blast waves shall be encompassing whole of New HGU & OHCU and

Existing H2 Bullets, H2 Plant, OHCU, HGU, CT’s & portion of DHDS Unit. However, H2S IDLH

Concentration shall be limited to vicinity of leakage.

In Addition the above case following more cases; Naphtha Feed Pump Seal Failure (SL. No.6 & figure

6.5.1.3.2 A-D) & Instrument Tapping Failure on top outlet line of Stripper Ovhd. Separator (SL. No.7 &

figure 6.5.1.3.2 A-D) were modeled and it was observed that the outcome of consequence analysis for

these failure scenarios shall be limited to vicinity of leakage and their affect zone is limited to B/L’s of the

Unit.




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In normal operation natural gas will be used as a feed and naphtha surge drum will not be in operation.

Naphtha as a feed shall be used occasionally. Hence the above failure scenarios have no major

concern.

6.5.1.4 SULPHUR RECOVERY UNIT (SRU)

Instrument Tapping Failure in Acid Gas K.O Drum-(TOXIC): From the consequence analysis (SL. No.8

& figure 6.5.1.4.1 A) of this failure scenario it can be observed that H2S IDLH concentration shall be

extended upto existing MSQ Unit, SRU Unit, New ETP Unit and MSQ-CR & its Substation, LPG Sphere

area Operator cabin, affecting personnel’s present in these buildings. Moreover the H2S IDLH

concentration may cross the Refinery Compound wall on western side and affecting the population

beyond compound wall, if present.

6.5.1.5 ONCE THROUGH HYDROCRACKER (OHCU)

Charge Pump Instrument Tapping Failure: From Consequence analysis (SL. No.9 & figure 6.5.1.5.1 A-

D) of this failure scenario, it can be inferred that the Flash Fire and 5 & 3 psi blast waves shall be

damaging equipments in OHCU & may extends upto New HGU Unit. The 37.5 & 12.5 Kw/m2 Radiation

intensity on account of Jet Fire shall be limited to immediate vicinity of the leak. However 12.5 Kw/m2

Radiation experienced on account of Pool Fire shall be crossing the unit’s B/L and may get spread up to

Compound wall on southern side and small portion of H2 Plant.

Stripper Ovhd Pump Instrument Tapping Failure: From the outcomes of consequence analysis (SL.

No.11 & figure 6.5.1.5.3 A-D) of this failure scenario it can be observed that LFL shall be extended up to

New HGU Unit. The 37.5 & 12.5 Kw/m2 Radiation intensity on account of Jet Fire may damage the

equipments in vicinity of leakage in OHCU and also extends up to nearby New HGU. The 5 & 3 psi blast

wave shall be affecting most of equipments in OHCU, New HGU and NSU. The H2S IDLH concentration

shall be covering almost all of the Process Units and associated CR’s & Substations and may even

crosses the Boundary wall on Southern & Eastern side of the Refinery affecting individuals present.

Product Fractionator Receiver Catastrophic Rupture: From the consequence graphs (SL. No.12 & figure

6.5.1.5.4 A-B) of this failure scenario, it can be observed that LFL shall spreading within the unit. The 5

psi blast wave shall be affecting all the equipments of New OHCU, NSU & HGU and even crosses the

Refinery Compound wall on southern side affecting Truck parking area. The 3 psi blast wave may

further propagate and affects equipments in H2 Plant & HGU Unit.

Kerosene Stripper Bottom Pump Instrument Tapping Failure: From the outcomes of consequence

analysis (SL. No.13 & figure 6.5.1.5.5 A-C) of this failure scenario it can be observed that LFL shall be

extended up to New HGU Unit. The 37.5 & 12.5 Kw/m2 Radiation intensity on account of Jet Fire affect

zone shall be limited to unit’s B/L itself. The 5 & 3 psi blast wave may damage most of the equipments

in OHCU and extends upto New HGU and may crosses unit’s B/L on western side also.




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Debutanizer Receiver Catastrophic Rupture: From the incident outcome analysis (SL. No.15 & figure

6.5.1.5.7 A-C) of this failure scenario, it can be observed that the Flash Fire affect zone shall be limited

to vicinity of B/L’s of unit itself. The 5 & 3 psi blast wave spreads in OHCU unit and also extends into

New HGU unit. The H2S IDLH concentration may extend beyond the unit’s B/L up to New HGU, Sub

Officers Residence, relocated Ware House & Store Shed, New CT’s, Proposed New CR for Slurry

Hydrocracker & SHCU and Existing DHDT Unit, DHDS Unit & their CR, Substation, Existing H2 Bullets,

OHCU, H2 Plant, HGU, Off Building, CT’s, Chemical House. The H2S IDLH concentration may also

extends beyond the Compound wall of Refinery on Southern side and affects population present there.

In Addition the above case following more cases; Recycle Gas Compressor Instrument Tapping Failure

(SL. No.10 & figure 6.5.1.5.2 A-C), Diesel Product Pump Seal Failure (SL. No.14 & figure 6.5.1.5.6 A-B)

were modeled and it was observed that the outcome of consequence analysis for these failure

scenarios shall be limited to vicinity of leakage and their affect zone is limited to B/L’s of the Unit.

6.5.1.6 RESID HYDROCRACKING UNIT

Recycle Gas Compressor Instrument Tapping Failure: From Incident Outcome Analysis (SL. No.16 &

figure 6.5.1.6.1 A-C) of this failure scenario, it can be observed that Flash Fire affect zone shall be

restricted within the unit. The 37.5 & 12.5 Kw/m2 Radiation intensity on account of Jet Fire shall also be

restricted with the unit. The 5 & 3 psi blast wave affect zone shall mostly be restricted with the unit and

may to the road no.XI near the unit in west side. H2S IDLH concentration shall also be restricted with the

unit warranting no cause for concern.

Fractionator Ovhd. Accumulator Catastrophic Rupture: From the consequence analysis (SL. No.17 &

figure 6.5.1.6.2 A-C) of this failure scenario it can be observed that LFL shall be spreading beyond the

B/L’s of the unit, extending up to New ETP, New SRU Block, New Control Room, LPG Spheres, PRU

Sphere, Mounded Bullets and may even cross the Compound wall on South side up to Marketing






Naphtha Product Pump Instrument Tapping Failure: From the incident outcome analysis (SL. No.19 &

figure 6.5.1.6.4 A-C) of this failure scenario it can be observed that the LFL shall be spreading





In addition the above case following more cases; VGO Product Pump Instrument Tapping Failure (SL.

No.18 & figure 6.5.1.6.3 A-C) and Diesel Product Pump Seal Failure (SL. No.20 & figure 6.5.1.6.5 A-C)




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were modeled and it was observed that the outcome of consequence analysis for these failure

scenarios shall be limited to vicinity of leakage and their affect zone is limited to B/L’s of the Unit.

6.5.1.7 OFFSITES

Diesel Tank on Fire: From the consequence graph (SL. No. 35 & figure 6.5.1.7.1 A) of this failure

scenario it can be observed that 32 Kw/m2 Radiation intensity shall not be realized. The 8 Kw/m2

Radiation intensity shall be limited to tankage surrounding itself, not affecting other nearby tankages

present.

HVGO Tank On Fire: From the consequence analysis ((SL. No. 36 & figure 6.5.1.7.2 A) of this failure

scenario it can be observed that 32 Kw/m2 Radiation intensity shall not be realized. The 8 Kw/m2

Radiation intensity shall be limited to tankage vicinity, not affecting other surrounding tankages.

LPG pump instrument tapping failure (LPG pump house): It will be evident from the results ((SL. No. 34

& figure 6.5.1.7.3 A-C) obtained that the consequences of flash fire, jet fire, & overpressure due to

instrument tapping failure on discharge line will be realized. The flash fire would cover the PH, LPG

sphere (070-V-01) and may approach to the new SRU and Resid Hydrocracking unit. Blast

overpressure of 5, 3 would affect the new SRU and Resid Hydrocracking unit partially. The thermal

radiation due to jet fire and pool fire of radiation intensity of 37.5kw/m2 and 12.5 kw/m2 would affect the

pump house and LPG sphere (070-V-01).

6.5.1.8 COOLING TOWER (CT)

Chlorine Toner Leakage: From the of consequence analysis (SL. No. 37 & figure 6.5.1.8.1 A) of this

failure scenario, it can be observed that any leakage from Chlorine Toner shall be going to affect the

total area under Mathura Refinery and even beyond the Compound walls of Refinery.

6.5.2 REVAMPED UNITS

6.5.2.1 CRUDE DISTILLATION UNIT (CDU)

Crude Charge Pump Instrument Tapping Failure: From Consequence Analysis (SL. No. 21 & figure

6.5.2.1.1 A-C) of this failure scenario, it can be observed that LFL is spreading beyond the B/L’s of the

Unit but not reaching up to any Unit/ Storage/ Facility. The 37.5 & 12.5 Kw/m2 Radiation intensity on

account of Jet Fire is also limited to B/L’s of the Unit, mostly producing localized damages. The 5 & 3 psi

blast wave is spreading within the Unit and crossing the Unit’s B/L on Northern & Western side affecting

Substation-8

Large Hole in Bottom Line of Atmospheric Column Reflux Drum: From Incident Outcome Analysis of

this failure scenario (SL. No. 22 & figure 6.5.2.1.3 A-D), it can be observed that Flash Fire affect zone is

getting extended beyond the Unit and extending up to VBU, CRU, Portion of FCC. The 37.5 & 12.5

Kw/m2 Radiation intensity on account of Jet Fire is spreading up to VBU, producing localized damage.

The 5 psi blast wave is damaging all of the equipments in CDU and affect zone is extended up to VBU,




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CRU, FCC, Portion of MSQ, Main CR, CRU Substation, Substation-8, CT’s & Tank nos.: 951, 952, 953,

954, 955, 956. The 3 psi blast wave further propagates & affects Tank nos.: 957, 958, 404, 002 and Fire

Water Tank: 186-T-01A. The 12.5 Kw/m2 Radiation intensity on account of Pool Fire is limited to leakage


Naphtha Stabilizer Reflux Drum Catastrophic Rupture: From the outcomes of Consequence Analysis

(SL. No. 26 & figure 6.5.2.1.6 A-B) of this failure scenario, it can be observed that LFL is restricted to

B/L’s of the Unit. The 5 & 3 psi blast waves are spreading throughout the unit and even beyond B/L’s of

the unit majorly affecting VBU, CRU Main Control Room, CRU Substation, Substation-8 and Tanks No.:

951, 953, 954.

Stabilizer Reflux Pump Instrument Tapping Failure: From the consequence graphs (SL. No. 27 & figure

6.5.2.1.7 A-C) of this failure scenario, it can be observed that LFL is spreading within the unit. The 37.5

& 12.5 Kw/m2 Radiation intensity on account of Jet Fire is limited to vicinity of leak, mostly producing

localized damage. The 5 & 3 psi blast wave is mostly spreading within the Unit and affecting small

portion of VBU of Eastern side.

In Addition the above case following more cases; Crude Booster Pump Seal Failure ((SL. No. 22 &

figure 6.5.2.1.2 A-C), Kero Product Pump Seal Failure (SL. No. 24 & figure 6.5.2.1.4 A-C), LGO Product

Pump Instrument Tapping Failure (SL. No. 25 & figure 6.5.2.1.5 A-C) were modeled and it was

observed that the outcome of consequence analysis for these failure scenarios are limited to vicinity of

leakage and their affect zone is limited to B/L’s of the Unit.

6.5.2.2 DIESEL HYDROTREATING UNIT (DHDT)

Feed Surge Drum Catastrophic Rupture: From Consequence Analysis (figure 6.5.2.2.1 A-C) of this

failure scenario, it can be observed that LFL is partially spreading beyond the unit. The 37.5 Kw/m2

Radiation intensity due to Pool Fire is affecting DHDT CR, its substation, all equipments in DHDT &

majority in DHDS and crossing the Compound Wall of Refinery on Eastern Side. The 12.5 Kw/m2

Radiations intensity due to Pool Fire further extends up to Ware House, Existing OHCU, H2 Bullets and

New proposed CT’s. The 5 & 3 psi blast wave is crossing the Unit’s B/L but are not reaching up to any

Unit/ Storage/ Building.

Charge Pump Instrument Tapping Failure: From the Incident Outcome Analysis (SL. No. 28 & figure

6.5.2.2.2 A-C) of this Failure Scenario, it can be observed that LFL is crossing the Unit’s B/L and

reaching up to DHDT CR & DHDS.

The 37.5 & 12.5 Kw/m2 Radiation intensity on account of Jet Fire is crossing the unit’s B/L but are not

reaching up to any Unit/ Storage/ Building. The 5 & 3 psi blast wave is spreading throughout the unit

affecting all the equipments and even beyond the B/L’s of the Unit affecting DHDS and DHDT CR &

Substation. The 37.5 & 12.5 Kw/m2 Radiation intensity on account of Pool Fire is crossing the unit’s B/L

affecting DHDS, DHDT CR, its Substation, New Proposed CT’s, H2 Storage, some portions of Existing

OHCU and crossing the Refinery Compound Wall on Eastern Side, affecting population present.




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Large Hole in the HP Cold Separator Bottom: From Consequence graphs (SL. No. 30 & figure 6.5.2.2.3

A-C) of this failure scenario, it can be observed that LFL is spreading beyond the unit and covering all of

the operating units of the refinery. It also crosses the Refinery compound wall on eastern side. The 37.5

& 12.5 Kw/m2 Radiation intensity on account of Jet Fire is damaging all the equipments within the unit &

crossing the unit’s B/L but is not reaching up to any Unit/ Storage/ Building. The 5 & 3 psi blast wave is

affecting all the Refinery units and affecting storages also. It also crosses the Refinery compound wall

on Eastern & Southern side affecting individuals present over there. H2S IDLH concentration spreads

beyond the B/L’s of the unit and extends up to CRU, FCC, Laboratory, Fire Station, Admin Building ,

Project Building, Warehouse, Workshop, Training Hall, Community Hall, New proposed Store Shed,

proposed warehouse, proposed store, proposed CT, proposed New HGU, proposed New OHCU,

existing OHCU, H2 Unit, New HGU, CT’s , Fire water tanks.

Recycle Gas Compressor Instrument Tapping Failure: From the outcomes of Consequence Analysis

(SL. No. 31 & figure 6.5.2.2.4 A-D) of this failure scenario, it can be observed that LFL is crossing the

unit’s B/L but not reaching upto any other Unit/Storage. The 37.5 & 12.5 Kw/m2 Radiation intensity on

account of Jet Fire is crossing the unit’s B/L but not reaching up to any other facility mostly producing

localized damage. The 5 & 3 psi blast wave is spreading throughout the unit affecting majorly all

equipments and even beyond the B/L’s of the Unit affecting nearby DHDS Unit. The H2S IDLH

concentration affect zone is limited to immediate vicinity of leakage, mostly producing localized damage.

In Addition the above case following more case; Stripper Reflux Pump Seal Failure (SL. No. 32 & figure

6.5.2.2.5 A-C) and Instrument Tapping Failure on Ovhd. line of HP Amine Absorber KOD (figure SL. No.

33 & 6.5.2.2.6 A-C) were modeled and it was observed that the outcome of consequence analysis for

this failure scenario is limited to vicinity of leakage and its affect zone is limited to B/L’s of the Unit.




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SECTION-7

7.1 LIST OF LAST MAJOR REFINERY INCIDENTS GLOBALLY IN LAST 10 YEARS

Today the refining industry finds itself the subject of a range of major accidents (explosions, fires,

emissions of dangerous materials, casualties) that have occurred over the last decade from which

important lessons can be learnt. The purpose of this list is to illustrate what the industry should learn

from recent major accidents and in such a way create opportunities for the future to prevent new major

accidents.

7.1.1 FIRE AND EXPLOSION AT CHEVRON RICHMOND REFINERY, USA

On August 6, 2012, the Chevron U.S.A. Inc. Refinery in Richmond, California, experienced a

catastrophic pipe failure in the #4 Crude Unit. The pipe ruptured, releasing flammable, hydrocarbon

process fluid which partially vaporized into a large vapor cloud that engulfed nineteen Chevron

employees. All of the employees escaped, narrowly avoiding serious injury. The flammable portion of

the vapor cloud ignited just over two minutes after the pipe ruptured. The ignition and subsequent

continued burning of the hydrocarbon process fluid resulted in a large plume of unknown and

unquantified particulates and vapor traveling across the Richmond, California, area. In the weeks

following the incident, approximately 15,000 people from the surrounding area sought medical treatment

due to the release. Testing commissioned by the U.S. Chemical Safety and Hazard Investigation Board

(CSB) and the California Division of Occupational Safety and Health (Cal/OSHA) determined that the

pipe failed due to thinning caused by sulfidation corrosion, a common damage mechanism in refineries.

As a result of the incident, the Chevron Richmond Refinery crude unit remains out of commission over

eight months later.

7.1.2 FIRE AND EXPLOSION AT AMUAY REFINERY, VENEZUELA

August 2012 - An explosion followed by fire tears through Venezuela's biggest refinery, killing 39

people, wounding dozens more and halting operations at the Amuay Refinery in Venezuela in the worst

accident to hit the OPEC nation's oil industry

7.1.3 TERMINAL FIRE AND EXPLOSION AT JAIPUR (INDIA)

A devastating fire/explosion accident occurred on 29 September, 2009 at about 7.30 pm in the POL

installation of M/S Indian Oil Corporation at Sitapura (Sanganer), Jaipur, and Rajasthan killing 11

persons and injuring 45. The product loss of around 60,000 KL has been reported. In this accident the

entire installation was totally destroyed and buildings in the immediate neighborhood were also heavily

damaged.

7.1.4 BUNCEFIELD TANK FARM FIRE AND EXPLOSION, UK

On 11 December, 2005 at approximately midnight, the terminal was closed to tankers and a stock check

of products was carried out. When this was completed at around 01.30, no abnormalities were reported.

From approximately 03.00, the level gauge for Tank 912 recorded an unchanged reading. However,

http://www.reuters.com/places/venezuela

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filling of Tank 912 continued at a rate of around 550 m3/hour. Calculations show that at around 05.20,

Tank 912 would have been completely full and starting to overflow. Evidence suggests that the

protection system which should have automatically closed valves to prevent any more filling did not

operate. From 05.20 onwards, continued pumping caused fuel to cascade down the side of the tank and

through the air, leading to the rapid formation of a rich fuel/air mixture that collected in bund A. At 05.38,

CCTV footage shows vapour from escaped fuel start to flow out of the north-west corner of bund A

towards the west. The vapour cloud was about 1 m deep. At 05.46, the vapour cloud had thickened to

about 2 m deep and was flowing out of bund A in all directions. Between 05.50 and 06.00, the pumping

rate down the T/K South pipeline to Tank 912 gradually rose to around 890 m3/hour. By 05.50, the

vapour cloud had started flowing off site near the junction of Cherry Tree Lane and Buncefield Lane,

following the ground topography. It spread west into Northgate House and Fuji car parks and towards

Catherine House. At 06.01, the first explosion occurred, followed by further explosions and a large fire

that engulfed over 20 large storage tanks. The main explosion event was centered on the car parks

between the HOSL West site and the Fuji and Northgate buildings. The exact ignition points are not

certain, but are likely to have been a generator house in the Northgate car park and the pump house on

the HOSL West site. At the time of ignition, the vapour cloud extended to the west almost as far as

Boundary Way in the gaps between the 3-Com, Northgate and Fuji buildings; to the north west it

extended as far as the nearest corner of Catherine House. It may have extended to the north of the

HOSL site as far as British Pipelines Agency (BPA) Tank 12 and may have extended south across part

of the HOSL site, but not as far as the tanker filling gantry. To the east it reached the BPA site.

7.1.5 EXPLOSION AND FIRE AT FORMOSA PLASTICS, ILLINOIS, USA

On April 23, 2004, five workers were fatally injured and two others were seriously injured when an

explosion occurred in a polyvinyl chloride (PVC) production unit at Formosa Plastics in Illiopolis, Illinois,

east of Springfield. The explosion followed a release of highly flammable vinyl chloride, which ignited.

The explosion forced a community evacuation and lighted fires that burned for several days at the plant.

7.1.6 EXPLOSION AND FIRE AT BP TEXAS REFINERY, USA

On March 23, 2005, fifteen people were killed and 180 injured following an explosion at this 460,000

bbl/d refinery. The explosion occurred in the isomerisation unit which had been shut down for its annual

maintenance. This unit was gradually being brought back on stream when the incident occurred. Further

investigations concentrated on a raffinate splitter as evidence pointed to a release of a flammable liquid

and vapor in that area of the plant. The distillation equipment was also being restarted following

maintenance work on the reactor. Many of the dead had been attending a meeting in a pair of trailers

near the area at the time of the explosion. The exact ignition source remains unknown but evidence

points to sources on the ground. Witnesses reported that there was a large hydrocarbon liquid and

vapor release from a 30 meter high vent stack moments before the ignition.




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SECTION-8

CONCLUSIONS AND RECOMMENDATIONS

The major conclusions and recommendations arising out of the Rapid Risk analysis study for the IOCL

Mathura Refinery are summarized below. This is based on the detail analysis given in Sections – 6.

NEW PROPOSED UNITS

NSU: Large Hole in Bottom line of Naphtha Splitter Ovhd. Separator: It can be observed from

consequence analysis of this failure scenario that LFL shall approach to the Refinery Compound wall on

south side and also extends into New HGU & OHCU. The Jet Fire Radiation Intensity of 37.5 & 12.5

Kw/m2 shall be affecting equipments in NSU as well as in OHCU. The 5 & 3 psi blast wave shall spread

throughout OHCU and covering majority of equipments in New HGU, moreover it shall also be crossing

Refinery Compound wall on southern side and engulfing the total truck parking & even extending

beyond it. The 12.5 & 4 Kw/m2 Radiation intensity on account of Pool Fire shall be limited to vicinity of

the unit.

As LFL shall be reaching up to the South Side Compound wall of the Refinery and 5 & 3 psi blast wave

shall be affecting Truck parking area, it is recommended to consider relocation of the Truck Parking

Area.

VDU: Vacuum Diesel Product/IR Pump Instrument Tapping Failure: From the Consequence

analysis of this failure scenario it can be observed that the LFL shall be crossing the unit’s B/L on

western side. The 37.5 & 12.5 Kw/m2 Radiation intensity on account of Jet Fire shall be extended

beyond the unit but will not be affecting any nearby unit or tankages. The 5 & 3 psi blast wave shall be

spreading throughout the unit damaging all the equipments and extending up to Tank No.: 951, 952,

953 and 954.


secondary incident arising from this failure, it is recommended that fire monitors and hydrant provided

around the tanks to be regularly checked to ensure that they are functional. Less hazardous equipments

(typically RCO pumps, hot oil system etc.) to be located on western side block of CDU.

SRU: Instrument Tapping Failure in Acid Gas K.O Drum-(TOXIC): From the consequence graph of

this failure scenario it can be observed that H2S IDLH concentration shall be extended upto existing

MSQ Unit, SRU Unit, New ETP Unit and MSQ-CR & its Substation, LPG Sphere area Operator cabin,

affecting personnel’s present in these buildings. Moreover the H2S IDLH concentration may cross the

Refinery Compound wall on western side and affecting the population beyond compound wall, if

present.

As H2S IDLH concentration shall be extended up to existing MSQ Unit, SRU Unit, any Temporary

Operator Cabin present in these units is to be removed / relocated. As MSQ-CR & its Substation are

positively pressurized, hence personnel in these building shall not be affected by H2S IDLH

concentration. Either relocation or positive pressurization of LPG Sphere area Operator cabin near LPG




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MCC room is recommended. Moreover, H2S detectors are to be installed at strategic locations. DMP &

ERP should include instructions for Human evacuations from above specified areas on priority, in any

case of leakage of H2S from SRU.

OHCU: Stripper Ovhd Pump Instrument Tapping Failure: From the outcomes of consequence

analysis of this failure scenario it can be observed that LFL shall be extended up to New HGU Unit. The

37.5 & 12.5 Kw/m2 Radiation intensity on account of Jet Fire may damage the equipments in vicinity of

leakage in OHCU and also extends up to nearby New HGU. The 5 & 3 psi blast wave shall be affecting

most of equipments in OHCU, New HGU and NSU. The H2S IDLH concentration shall be affecting

DHDT/DHDS control room, proposed new control room and substation, process cooling water control

room, substation-151/11, offsite utility substation, office building, drinking & fresh water control room,

eco office and may even crosses the Boundary wall on Southern side of the Refinery affecting

individuals present.

DHDT/DHDS control room and proposed ‘new control room & substation’ are positively pressurized;

hence personnel in these building shall not be affected by H2S IDLH concentration.

It is recommended to install H2S detectors with sirens at strategic location in the plant in the event of any

such leakage to alert personnel present in the existing building viz. process cooling water control room,

drinking and fresh water control room, office building and Eco office and evacuation procedures should

be in place to evacuate personnel.

Since H2S IDLH concentration crosses boundary wall on southern side, it is also recommended to install

H2S detectors with sirens on south side of the unit and DMP should address emergency evacuation

procedures in case of any such leakage. Since the truck parking area is located in the south side

outside plant boundary hence it is recommended to consider the relocation of Truck Parking Area.




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OHCU: Product Fractionator Receiver Catastrophic Rupture: From the consequence graphs of this

failure scenario, it can be observed that LFL shall spreading within the unit. The 5 psi blast wave shall

be affecting all the equipments of New OHCU, NSU & HGU and even crosses the Refinery Compound

wall on southern side affecting Truck parking area. The 3 psi blast wave may further propagate and

affects equipments in H2 Plant & HGU Unit.

Though LFL shall be restricted to B/L’s of the Unit, relocation of Truck Parking Area to be looked upon

as it is getting affected by 5 and 3 psi blast wave.

OHCU: Debutanizer Receiver Catastrophic Rupture: From the incident outcome analysis of this

failure scenario, it can be observed that the Flash Fire affect zone shall be limited to vicinity of B/L’s of

unit itself. The 5 & 3 psi blast wave spreads in OHCU unit and also extends into New HGU unit. The H2S

IDLH concentration may extend beyond the unit’s B/L up to New HGU, Sub Officers Residence,

relocated Ware House & Store Shed, New CT’s, Proposed New CR for Slurry Hydrocracker & SHCU

and Existing DHDT Unit, DHDS Unit & their CR, Substation, Existing H2 Bullets, OHCU, H2 Plant, HGU,

Off Building, CT’s, Chemical House. The H2S IDLH concentration may also extends beyond the

Compound wall of Refinery on Southern side and affects population present there.

It is recommended to install H2S detectors with sirens on East & South side B/L of the unit and DMP

should address emergency evacuation procedures in case of any such scenario. The manned building

within the affect zone of H2S IDLH should be evacuated on priority.

RESID HYDROCRACKING UNIT: Fractionator Ovhd. Accumulator Catastrophic Rupture: From

the consequence analysis of this failure scenario it can be observed that LFL shall be spreading beyond

the B/L’s of the unit, extending up to New ETP, New SRU Block, New Control Room, LPG Spheres,

PRU Sphere, Mounded Bullets and may even cross the Compound wall on South side up to Marketing






As LFL shall be reaching up to Truck Parking Area and it is also getting affected by 5 & 3 psi blast

wave, it is recommended to consider relocation / removal of Truck Parking Area.

RESID HYDROCRACKING UNIT: Naphtha Product Pump Instrument Tapping Failure: From the

incident outcome analysis of this failure scenario it can be observed that the LFL shall be spreading








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As Proposed New Control Room shall be getting affected by 5 & 3 psi blast wave, it is recommended to

be made Blast Proof with Positive Pressurization.

CT: Chlorine Toner Leakage: From the graphs of consequence analysis of this failure scenario, it can

be observed that any leakage from Chlorine Toner shall be going to affect the total area under Mathura

Refinery and even beyond the Compound walls of Refinery.

As Chlorine IDLH is affecting all the individuals inside Mathura Refinery and even beyond its Compound

wall, it is suggested to substitute / replace Chlorine with some other safer alternative viz. ClO2. In

absence of replacement it is recommended to install Cl2 detectors with sirens at strategic locations and

train people for emergency evacuation in case of Cl2 leakage. IOCL should also involve State level

authorities / District Administration in trainings/Mock drills, as Cl2 IDLH affect zone is extended beyond

the Compound Wall of Refinery, population in vicinity of the Refinery are to be informed about ill-effects

of Cl2.

REVAMPED UNITS

CDU: Large Hole in Bottom Line of Atmospheric Column Reflux Drum: From Incident Outcome

Analysis of this failure scenario, it can be observed that Flash Fire affect zone is getting extended

beyond the Unit and extending up to VBU, CRU, Portion of FCC. The 37.5 & 12.5 Kw/m2 Radiation

intensity on account of Jet Fire is spreading up to VBU, producing localized damage. The 5 psi blast

wave is damaging all of the equipments in CDU and affect zone is extended up to VBU, CRU, FCC,

Portion of MSQ, Main CR, CRU Substation, Substation-8, CT’s & Tank nos.: 951, 952, 953, 954, 955,

956. The 3 psi blast wave further propagates & affects Tank nos.: 957, 958, 404, 002 and Fire Water

Tank: 186-T-01A. The 12.5 Kw/m2 Radiation intensity on account of Pool Fire is limited to leakage


5 psi blast wave is affecting Main CR which is already of Blast proof construction. The affected tankage

should be provided with suitable fire fighting measures. In order to prevent secondary incident arising

from this failure, it is recommended that fire monitor and hydrant provided around the tanks to be

regularly checked to ensure that they are functional. Proper routine check to be ensured in the area to

prevent presence of any potential ignition source in the vicinity.

CDU: Naphtha Stabilizer Reflux Drum Catastrophic Rupture: From the outcomes of Consequence

Analysis of this failure scenario, it can be observed that LFL is restricted to B/L’s of the Unit. The 5 & 3

psi blast waves are spreading throughout the unit and even beyond B/L’s of the unit majorly affecting

VBU, CRU Main Control Room, CRU Substation, Substation-8 and Tanks No.: 951, 953 and 954.

Ensure the blast proof construction of CRU Main Control Room & its Substation, Substation-8.


secondary incident arising from this failure, it is fire monitor and hydrant provided around the tanks to be

regularly checked to ensure that they are functional.




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DHDT: Large Hole in the HP Cold Separator Bottom: From Consequence graphs of this failure

scenario, it can be observed that LFL is spreading beyond the unit and covering all of the operating

units of the refinery. It also crosses the Refinery compound wall on eastern side. The 37.5 & 12.5 Kw/m2

Radiation intensity on account of Jet Fire is damaging all the equipments within the unit & crossing the

unit’s B/L but is not reaching up to any Unit/ Storage/ Building. The 5 & 3 psi blast wave is affecting all

the Refinery units and affecting storages also. It also crosses the Refinery compound wall on Eastern &

Southern side affecting individuals present over there. H2S IDLH concentration spreads beyond the

B/L’s of the unit and extends up to CRU, FCC, Laboratory, Fire Station, Admin Building , Project

Building, Warehouse, Workshop, Training Hall, Community Hall, New proposed Store Shed, proposed

warehouse, proposed store, proposed CT, proposed New HGU, proposed New OHCU, existing OHCU,

H2 Unit, New HGU, CT’s , Fire water tanks.

Though the Failure Frequency of such an incident is remote, H2S detectors at suitable locations within

the unit shall be ensured. The virtue of extent of damages by this case can be utilized for making an

efficient DMP. The probability of such an incident can be further reduced by efficient monitoring of

vessel internals during shut-down.

GENERAL RECOMMENDATIONS

It is recommended to interchange the locations of new proposed OHCU and HGU in order to

further reduce the hazard beyond the southern side of the compound wall of the refinery.

It is recommended that the HP section and toxic section are to be located towards the north east

side of the unit in equipment layout of Resid Hydrocracking unit on account of close proximity of

LPG and propylene sphere.

In the event of any leakage from existing LPG P/H which may affect adjacent new unit (Resid

Hydrocracking Unit) in case if the release gas finds any ignition source in its path. It is therefore

recommended to restrict the traffic movement on all the roads around the existing sphere area to

avoid the presence of ignition source.

Hydrocarbon detector with alarm shall be provided at strategic location on west side of the

sphere in the event of any leakage from existing LPG P/H which may get ignited because of

ignition source from moving rail wagon. Hence therefore it is recommended to stop the rail

wagon movement immediately on actuation of hydrocarbon detector alarm.

Proper barricading during construction phase of new units of proposed residue Upgradation

project from the existing units to be done.

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.

The vehicles entering the Refinery complex should be fitted with spark arrestors as a mandatory

item.




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In order to prevent secondary incident arising from any failure scenario, it is recommended that

sprinklers and other protective devices provided on the tanks to be regularly checked to ensure

that they are functional.

Emergency security / evacuation drills to be organized at organization level to ensure

preparation of the personnel’s working in IOCL-MR for handling any extreme situation.

MITIGATING MEASURES









IGNITION CONTROL




ESCAPE ROUTES









OTHERS




Ensure breathing apparatus at strategic locations inside Refinery.




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MITIGATING MEASURES









IGNITION CONTROL




ESCAPE ROUTES









OTHERS




Ensure breathing apparatus at strategic locations inside Refinery




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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




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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).

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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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, Cremer & 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’.

7. Plot plan A260-000-1647-0001, Rev H.

ANNEXURE-I

CONSEQUENCE ANALYSIS HAZARD DISTANCES

ANNEXURE-II

FIGURES FOR CONSEQUENCE ANALYSIS

ANNEXURE-III

OVER ALL PLOT PLAN

Documents

HAZARDS ASSOCIATED WITH FLAMAMBLE … · 1.1 project description ... 6.5.1.6 resid hydrocracking unit ... 7.1 list of last major refinery incidents globally in last 10 years