RAPID RISK ANALYSIS STUDY OF PROPOSED RESIDUE UPGRADATION PROJECT AT MATHURA, UTTAR PRADESH PREFACE

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2 Page 2 of 45 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.

3 Page 3 of 45 TABLE OF CONTENTS SECTION EXECUTIVE SUMMARY PROJECT DESCRIPTION CONCLUSIONS AND RECOMMENDATION... 6 SECTION INTRODUCTION STUDY AIMS AND OBJECTIVE SCOPE OF WORK PROCESS DESCRIPTION RESID HYDROCRACKER UNIT (REHU) OTHERS UNIT SECTION SITE CONDITION GENERAL SITE, LOCATION AND VICINITY METEOROLOGICAL CONDITIONS SECTION HAZARDS ASSOCIATED WITH THE PROJECT GENERAL HAZARDS ASSOCIATED WITH FLAMAMBLE MATERIALS HYDROGEN NAPHTHA AND OTHER HEAVIER HYDROCARBONS HAZARDS ASSOCIATED WITH TOXIC/CARCINOGENIC MATERIALS HYDROGEN SULPHIDE CHLORINE SECTION HAZARD IDENTIFICATION GENERAL... 21

4 Page 4 of MODES OF FAILURE SELECTED FAILURE CASES SECTION CONSEQUENCE ANALYSIS GENERAL CONSEQUENCE ANALYSIS MODELLING DISCHARGE RATE DISPERSION FLASH FIRE JET FIRE POOL FIRE VAPOR CLOUD EXPLOSION TOXIC RELEASE SIZE AND DURATION OF RELEASE DAMAGE CRITERIA LFL OR FLASH FIRE THERMAL HAZARD DUE TO POOL FIRE, JET FIRE AND FIRE BALL VAPOR CLOUD EXPLOSION TOXIC HAZARD CONSEQUENCE ANALYSIS OF THE SELECTED FAILURE CASES NEW PROPOSED UNITS NAPHTHA SPLITTER UNIT (NSU) VACUUM DISTILLATION UNIT (VDU) HYDROGEN GENERATION UNIT (HGU) SULPHUR RECOVERY UNIT (SRU) ONCE THROUGH HYDROCRACKER (OHCU) RESID HYDROCRACKING UNIT OFFSITES COOLING TOWER (CT)... 31

5 Page 5 of REVAMPED UNITS CRUDE DISTILLATION UNIT (CDU) DIESEL HYDROTREATING UNIT (DHDT) SECTION LIST OF LAST MAJOR REFINERY INCIDENTS GLOBALLY IN LAST 10 YEARS FIRE AND EXPLOSION AT CHEVRON RICHMOND REFINERY, USA FIRE AND EXPLOSION AT AMUAY REFINERY, VENEZUELA TERMINAL FIRE AND EXPLOSION AT JAIPUR (INDIA) BUNCEFIELD TANK FARM FIRE AND EXPLOSION, UK EXPLOSION AND FIRE AT FORMOSA PLASTICS, ILLINOIS, USA EXPLOSION AND FIRE AT BP TEXAS REFINERY, USA SECTION CONCLUSIONS AND RECOMMENDATIONS GLOSSARY REFERENCES ANNEXURE-I: CONSEQUENCE ANALYSIS HAZARD DISTANCES ANNEXURE-II: FIGURES FOR CONSEQUENCE ANALYSIS ANNEXURE-III: OVER ALL PLOT PLAN

6 Page 6 of 45 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/m 2 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/m 2 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/m 2 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

7 Page 7 of 45 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 H 2 S 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 H 2 S IDLH concentration may cross the Refinery Compound wall on western side and affecting the population beyond compound wall, if present. As H 2 S 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 H 2 S IDLH concentration. Either relocation or positive pressurization of LPG Sphere area Operator cabin near LPG MCC room is recommended. Moreover, H 2 S 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 H 2 S 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/m 2 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 H 2 S 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 H 2 S IDLH concentration. It is recommended to install H 2 S 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 H 2 S IDLH concentration crosses boundary wall on southern side, it is also recommended to install H 2 S 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.

8 Page 8 of 45 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 H 2 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 H 2 S 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 H 2 Bullets, OHCU, H 2 Plant, HGU, Off Building, CT s, Chemical House. The H 2 S IDLH concentration may also extends beyond the Compound wall of Refinery on Southern side and affects population present there. It is recommended to install H 2 S 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 H 2 S 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/m 2 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/m 2 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.

9 Page 9 of 45 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. ClO 2. In absence of replacement it is recommended to install Cl 2 detectors with sirens at strategic locations and train people for emergency evacuation in case of Cl 2 leakage. IOCL should also involve State level authorities / District Administration in trainings/mock drills, as Cl 2 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 Cl 2. 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/m 2 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/m 2 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. The affected tankage should be provided with suitable fire fighting measures. In order to prevent 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.

10 Page 10 of 45 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/m 2 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. H 2 S 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, H 2 Unit, New HGU, CT s, Fire water tanks. Though the Failure Frequency of such an incident is remote, H 2 S 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.

11 Page 11 of 45 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 H 2 S prone area, it is to be ensured to carry portable H 2 S detector. Ensure breathing apparatus at strategic locations inside Refinery.

12 Page 12 of 45 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

13 Page 13 of 45 Offsite facilities: Utilities HSD Tank HVGO Tank DHDT Feed Tank Mounded bullet 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 2x30 MWhr Generator 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: 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

14 Page 14 of 45 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 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.

15 Page 15 of 45 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 East and 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 ( ) 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 ( O C) Atmospheric Pressure (mm Hg) Relative Humidity (%) Solar Radiation flux (kw/m 2 ) 0.7

16 Page 16 of 45 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 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 indicates the various Pasquill stability classes. Table 3.3-3: Pasquill Stability Classes Surface Wind Speed Day time solar radiation Night time cloud cover (meter/s) Strong Medium Slight Thin < 3/8 Medium 3/8 Overcast >4/5 < 2 A A B B - - D

17 Page 17 of 45 Surface Wind Speed Day time solar radiation Night time cloud cover (meter/s) 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

18 Page 18 of 45 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 HYDROGEN Hydrogen (H 2 ) 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) UFL (%v/v) Auto ignition temperature ( C) Heat of combustion (Kcal/Kg) Normal Boiling point ( C) Flash point ( C) N.A 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

19 Page 19 of 45 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) UFL (%v/v) Auto ignition temperature ( C) Heat of combustion (Kcal//Kg) 10, Normal Boiling point ( C) Flash point ( C) HAZARDS ASSOCIATED WITH TOXIC/CARCINOGENIC MATERIALS 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 Threshold Limit Value(TLV) Short Term Exposure Limit (STEL) (15 Minutes) Immediately Dangerous to Life and Health (IDLH) level (for 30 min exposure) 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

20 Page 20 of 45 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

21 Page 21 of 45 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

22 Page 22 of 45 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.

23 Page 23 of 45 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.

24 Page 24 of 45 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 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 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 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.

25 Page 25 of 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 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 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 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 Pump Seal Failure Flange Gasket Failure Instrument Tapping Failure Large Hole Catastrophic Failure LEAK SIZE 6 mm hole size 10 mm hole size 20 mm hole size 50 mm, complete rupture of 2 drain line Complete rupture of pressure vessels

26 Page 26 of 45 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 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 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 Maximum flux level for thermally protected tanks containing flammable liquid Minimum energy required for piloted ignition of wood, melting of plastic tubing etc. 8.0 Maximum heat flux for un-insulated tanks Sufficient to cause pain to personnel if unable to reach cover 4.0 within 20 seconds. However blistering of skin (1st degree burns) is likely. The hazard distances to the 37.5 kw/m 2, 32 kw/m 2, 12.5 kw/m 2, 8 kw/m 2 and 4 kw/m 2 radiation levels, selected based on their effect on population, buildings and equipment were modeled using PHAST 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

27 Page 27 of 45 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 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 NEW PROPOSED UNITS 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 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