RAPID RISK ASSESSMENT REPORT For IOCL … RISK ASSESSMENT REPORT FOR IOCL PANIPAT REFINERY Project: BS VI Fuel Quality Upgradation and Capacity Expansion of …

RAPID RISK ASSESSMENT REPORT FOR

IOCL PANIPAT REFINERY

Project: BS VI Fuel Quality Upgradation and Capacity Expansion of PX/PTA

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RAPID RISK ASSESSMENT REPORT For


BS VI FUEL UPGRADATION AND CAPACITY EXPANSION OF PX/PTA

1 16.01.2017 FINAL REPORT VJK VKM YTK

0 26.12. 2016 ISSUED FOR REVIEW VJK VKM YTK

REV. DATE DESCRIPTION PREPARED BY (Initials)

CHECKED BY (Initials)

APPROVED BY (Initials)

V

For




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CONTENTS

1. PROJECT INTRODUCTION ........................................................................................................ 9

2. OBJECTIVE AND SCOPE OF WORK ......................................................................................... 9

3. PROJECT DESCRIPTION ......................................................................................................... 10

3.1. PX-PTA Capacity Expansion ............................................................................................. 11

4. RRA METHODOLOGY .............................................................................................................. 13

4.1. Hazards Identification ........................................................................................................ 16

4.2. Characterising the Failures................................................................................................ 17

4.3. Operating Parameters ....................................................................................................... 17

4.4. Inventory ........................................................................................................................... 18

4.5. Loss of Containment ......................................................................................................... 18

5. CONSEQUENCE ANALYSIS .................................................................................................... 18

5.1. Weather Conditions ........................................................................................................... 18

5.2. Hazards associated with Flammable Materials .................................................................. 20

5.3. Damage Criteria ................................................................................................................ 20

5.4. Source Strength Parameters ............................................................................................. 20

5.5. Consequential Effects ....................................................................................................... 20

5.6. Selection of Damage Criteria ............................................................................................. 21

5.7. Heat Radiation .................................................................................................................. 21

5.8. Explosion .......................................................................................................................... 23

5.9. Consequence Analysis ...................................................................................................... 24

6. RISK ASSESSMENT ................................................................................................................. 33

6.1. Ignition Sources ................................................................................................................ 33

6.2. Site Location and Vicinity .................................................................................................. 34

6.3. Population Data ................................................................................................................. 34

6.4. Location Specific Individual Risk (LSIR) ............................................................................ 37

6.5. Individual Risk Criteria ....................................................................................................... 37

6.6. Risk criteria for Societal Risk ............................................................................................. 38

7. RISK RESULTS ......................................................................................................................... 39

7.1. Location Specific Individual Risk (LSIR) Results ............................................................... 39

7.2. Societal Risk ..................................................................................................................... 40

8. CONCLUSIONS & RECOMMENDATIONS ............................................................................... 41

8.1. Technical Recommendations: ........................................................................................... 42

9. REFERENCES ........................................................................................................................... 44




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ANNEXURE – I ISOLATABLE SECTION ............................................................................................. 45

ANNEXURE – II – CONSEQUENCE RESULTS .................................................................................... 47

List of Tables: Table 1 : Pasquill’s Atmospheric stability class .......................................................................................................... 18 Table 2 : Damages to Human Life Due to Heat Radiation ......................................................................................... 21 Table 3 : Radiation intensity ....................................................................................................................................... 22 Table 4 : Damage Due To Overpressures ................................................................................................................. 23 Table 5: LOC Scenarios Identified in the Study ......................................................................................................... 24 Table 6: Flammable Results ....................................................................................................................................... 26 Table 7: Summary of Toxic Dispersion Results ......................................................................................................... 32 Table 8: Summary of Overpressure Explosion Results.............................................................................................. 32 Table 9 : Occupancy Data .......................................................................................................................................... 35 Table 10: Location Specific Risk Value ...................................................................................................................... 40 List of Figures: Figure 1: Risk Assessment – Conceptual Framework ............................................................................................... 14 Figure 2: RRA Study Flow .......................................................................................................................................... 15 Figure 3: RRA Methodology ....................................................................................................................................... 16 Figure 4: Site Location ................................................................................................................................................ 34 Figure 5: Individual Risk Acceptance Criteria ............................................................................................................. 37 Figure 6: Societal Risk Acceptance Criteria ............................................................................................................... 38 Figure 7: Combined LSIR Contour for Project facility ................................................................................................. 39 Figure 8: F-N curve ..................................................................................................................................................... 41




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ABBREVIATION AND DEFINITION

Abbreviation

ALARP As Low As Reasonably Practicable

BLEVE Boiling Liquid Expanding Vapour Explosion

DNV Det Norske Veritas

F-N Fatality vs Number of People

FG Fuel Gas

OGP Oil & Gas Production (Risk Assessment Data Directory)

HAZID Hazard Identification

HC Hydrocarbon

HSE Health, Safety and Environment

KOD Knock Out Drum

LEL Lower Explosive Limit

LFL Lower Flammability Limit

LTC L&T Chiyoda Limited

MAE Major Accident Event

OISD Oil Industry Safety Directorate

P&ID Piping & instrumentation Diagram

PFD Process Flow Diagram

PSV Pressure Safety Valve

PPE Personnel Protective Equipment

SDV Shutdown Valve

TLV Threshold limit valve

QRA Quantitative Risk Assessment




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UEL Upper Explosive Limit

UFL Upper Flammability Limit

VCE Vapour Cloud Explosion

Definition

For the purposes of this specification, the following definitions shall apply:

Hazard: Potential to cause harm, including ill health and injury, damage to the environment, property, or production losses.

Frequency: Number of occurrences of an event per unit of time

ALARP: The degree of risk in a particular activity or environment can be balanced against the time, trouble, cost and physical difficulty of taking measures to avoid the risk.

Risk: A measure of human injury, environmental damage or economic loss in terms of both the incident likelihood and the magnitude of the loss or injury.

Jet Fire: Ejection of flammable liquid from a vessel, pipe or pipe flange can give rise to a jet flame if the material ignites. Scenarios involving jet flames are not easy to handle, since a large jet flame may have a substantial reach sometimes up to 50 m or more.

Flash fire: In a flash fire the gas cloud burns, but does not explodes. A typical flash fire may cause quite extensive damage, particularly to vulnerable, but may leave main plant equipment relatively unharmed. However, a flash fire does cause a sudden depletion of oxygen, and this effect can be lethal to personnel.

Pool Fire: If the leak forms a liquid pool on the ground, this may ignite and burn. The flame may be substantial and may do damage by direct impingement or by radiation.

VCE (Vapour Cloud Explosion): When a cloud of flammable vapour burns, the combustion may give rise to an overpressure, or it may not. If there is no over pressure, the event is a vapour cloud fire, or flash fire, and if there is over pressure, it is a vapour cloud explosion. Vapour cloud explosion was generally referred to as an unconfined vapour cloud explosion.

BLEVE (Boiling Liquid Expanding Vapour cloud Explosion): BLEVE generally occurs when a pressure vessel containing a flammable liquid is exposed to fire so that the metal loses strength and ruptures.

Consequences: Event or chain of events that results from the release of a Hazard.

Escalation: Propagation of the Hazard after the incident if nothing else is done to recover the situation.

Scenario: Chain of events between one or multiple causes related to one deviation leading to one chain of consequences and protected by one or multiples safeguards.




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Dispersion: Distance to Lower Flammability Limit (LFL) is addressed to check safety distance to strong point ignition sources.

Likelihood: The Probability of an event or situation taking place.

Mitigation: The elimination or reduction of frequency, magnitude of exposure to risk.

Domino Effect: Domino effect is the propagation of an accident originated from a specific equipment or inventory to adjacent equipment or areas from an industrial site.




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EXECUTIVE SUMMARY

The study team identified 30 numbers of scenarios for the RRA study. Considering the risk contours and FN curve for combination of all scenarios, DNV- PHAST RISK (SAFETI) software has been used for estimating the risk.

The following interpretations are derived from the risk results of this study:

Individual risk is in the ALARP region of the UK HSE Individual risk acceptance criteria.

The societal risk is in the ALARP region of the UK HSE Societal risk acceptance criteria.

The conclusions based on the RRA study outcome are listed below:

This RRA report represents the worst case scenario for all the consequences. Maximum inventory and maximum pressure have been considered as an initial cause for worst case scenario. It was observed that there are no foreseen hazards due to depressurisation after blow down. Hence report doesn’t take any

credit for the blow down. It has been observed that the consequence results are not having any adverse effects on the facilities.

Risk is combination of consequence and failure frequency of the scenario. Consequences are found to be higher because of the availability of flammable gas/liquid and high pressure in the process. However the probabilities of the failure are in the acceptable range (1E-4 to 1E-7). Hence the risk falls under As Low As Reasonably Practicable (ALARP) region.

Following are the safety measures have been adopted in the plant.

1 Emergency isolation valves are provided with manual mode that will close them immediately through push button located at a safe place and auto mode that will close them immediately through gas/fire detector system.

2 The Vessels/ tanks are designed as per standards and corrosion protection is accounted in the design.

3 Material of Construction of vessels is assumed to be suitable for the process conditions.

4 The facilities are well designed as per acceptable Indian / International codes & standards.

5 Inherent safety like appropriate equipment spacing as per OISD-118, Hazardous area classification is considered.

6 Passive fire protection such as fire proofing shall be provided.

7 Appropriate detection measures such as fire and gas detectors are to be provided and verified throughout the plant area.

8 Use of separate Fire and Gas PLC (programmable logic controllers) for operation of gas Detector and hardwiring of emergency switches for all new plants and facilities.




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9 Inter distance Analysis for the facilities has been performed as per OSID standard and the facilities are located safely.

Overall Risk is in ALARP region and plant is equipped with well-defined safety measures and no additional safety mitigation measures are recommended for the Plant.




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1. PROJECT INTRODUCTION

Panipat refinery, a unit of Indian Oil Corporation Limited (IOCL) operates a 15.0 Million Metric Tons Per Annum (MMTPA) oil refinery at Panipat in Haryana. The refinery was commissioned in 1997-98 and started off with a crude oil processing capacity of 6.0 MMTPA (PR- Panipat Refinery). The refinery capacity was raised to 12.0 MMTPA with the addition of another crude unit and a full conversion hydrocracker as the secondary processing unit and Delayed Coker unit for bottom processing (PREP- Panipat Refinery Expansion Project). Through progressive revamps and addition of process units the refining capacity has been brought to the present operating capacity of 15.0 MMTPA (PRAEP- Panipat Refinery Additional Expansion Project). IOCL Panipat is also integrated with Naphtha Cracker and Aromatic Complex.

In current refinery operations data corresponding to year 2015, refinery produces Gasoline & Diesel conforming to BS-IV specifications. However with the objective of meeting the guidelines established in Auto Fuel Policy 2025 wherein it would be required to manufacture 100% BS-VI fuels, a study has been carried out to analyze the potential for conforming to the mandate as described above by 2020 as envisaged by Govt. of India.

2. OBJECTIVE AND SCOPE OF WORK

Scope of the RRA study for the following area:

To be Revamped Units:

1. Diesel Hydro De-Sulphurisation (DHDS),

2. Prime-G,

3. Para Xylene Unit, and

4. Purified Terephthalic Acid Unit (PTA)

New Units:

1. Diesel Hydro-Treater (DHDT)

2. Hydrogen Generation Unit

3. Tertiary Amyl Methyl Ether

4. OCTAMAX

5. Sulphur Recovery Unit (SRU) with Tail Gas Treating Unit (TGTU)

6. Amine Regeneration Unit (ARU)

7. Sour Water Stripper (SWS)

8. DHDT feed tank




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3. Project Description

Panipat refinery, a unit of Indian Oil Corporation Limited (IOCL) operates a 15.0 Million Metric Tons Per Annum (MMTPA) crude oil refinery at Panipat in Haryana. The refinery was commissioned in 1997-98 and started off with a crude oil processing capacity of 6.0 MMTPA. The refinery capacity was raised to 12.0 MMTPA with addition of another crude unit and a full conversion hydrocracker as the secondary processing unit and Delayed Coker unit for bottom processing. Through progressive revamps and addition of process units, the refining capacity has been further brought to the present operating capacity of 15.0 MMTPA. IOCL, Panipat is also integrated with Naphtha Cracker and Aromatic Complex.

In current refinery operations data corresponding to year 2016, refinery produces Gasoline & Diesel conforming to BS-IV specifications. However, with the objective of meeting the guidelines established in Auto Fuel Policy 2025 wherein it would be required to manufacture 100% BS-VI fuels, a study has been carried out by Engineers India Limited (for existing refinery – 15.0 MMTPA) to analyse the potential for conforming to the mandate as described above by 2020 as envisaged by Govt. of India.

The major scope of the study by EIL is to identify new units, revamp of existing units, discreet investments and operating costs associated with the reduction in sulphur content of gasoline and diesel from BS IV compliance to BS VI specification, whilst maintaining the yields of the major products (MS and HSD) and carry out CAPEX cost estimation of revamp / new units at ± 30% accuracy level.

As part of the study, the base case is established initially for 15.0 MMTPA, which corresponds to 100% MS and Diesel production conforming to BS-IV specification, i.e. sulphur specification of 50 ppmw for both MS and Diesel. During BS-VI scenario, capacity of Panipat Refinery is also considered to be 15 MMTPA while entire MS and HSD production complying BS-VI specification i.e. sulphur specification of 10 ppmw for both MS and Diesel.

To meet the above requirement at Panipat Refinery, following new units / revamp of existing units are required to be executed:

1. New DHDT of capacity 2.2 MMTPA

2. New hydrogen generation unit of capacity 44 KTPA

3. Revamp of existing DHDS from 0.7 MMTPA to 1.0 MMTPA

4. Revamp of existing Prime G unit

5. New FG amine treating unit of 6 TPH

6. New SRU+TGT of 225 TPD capacity

7. New Amine Regeneration unit of capacity 84 TPH

8. New sour water stripper of capacity 16.4 m3/hr

9. TAME & Octamax unit for production of 95 RON MS




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10. New DHDT feed tank of capacity 20000 m3

3.1. PX-PTA Capacity Expansion

3.1.1. Introduction:

Para-xylene is a key petrochemical intermediate used in the production of Purified TerePhthalic Acid which in turn is utilized in manufacture of synthetic fibres and PET resins. The synthetic fibres and PET respectively form the base for production of textiles and packaging applications such as polyester fabrics and fleece, water and soft drink bottles, films and thermoformed containers.

In 2014, demand for polyester reached 47 Million Ton, making it the most commonly used synthetic fibre worldwide. In the same year, 22 Million Ton of PET resin was consumed.

3.1.2. PX-PTA Plant at Panipat Refinery

Indian Oil stepped into the Petrochemical venture by setting up a Linear Alkyl Benzene plant at Gujarat Refinery in 2004. Subsequently in the year 2006, a facility for manufacturing Purified Terephthalic Acid (PTA) at Panipat Refinery was setup. A Para-xylene complex was setup to make the feed for the PTA plant. The feed to PX complex comprised Naphtha from Panipat Refinery as well as Naphtha from other IOC Refineries.

The Para-xylene complex has a production capability of 360 kilo Tons Per Annum (kTPA) of PTA feed and PTA plant has a capacity of 553 kTPA. The plant is licensed by M/s UOP, USA.

IndianOil's Purified Terepthalic Acid (PTA) plant was commissioned at Panipat Refinery, Haryana in June 2006 as a response to expansion in the downstream polyester sector and also in the light of liquid fuel (Naphtha) surpluses in the Northern Sector. The fully integrated plant uses Para Xylene (PX) produced by Panipat Refinery as the main feed stock for manufacture of PTA. PX is produced from aromatic rich heart cut of Naphtha.

Initially crude Terepthalic Acid is produced through oxidation of PX in the presence of a catalyst. Crude Terepthalic Acid is then purified through a process of hydrogenation, crystallization, centrifuging and drying to produce PTA. While PX plant is based on the latest UOP technology, PTA plant is based on the proven Invista T10 (currently DuPont) technology.

The PX-PTA plant had a capital outlay of around Rs.5100 crores. The nameplate capacity of 3,60,000 TPA of in-house PX is ideally matched with the rated capacity of 5,53,000 TPA of PTA. Benzene to the tune of 25,000 TPA is generated during the process and is separated out by fractionation.

3.1.2.1.Applications PTA is predominantly used as a raw material in manufacture of Polyester Staple Fibres, Polyester Filament Yarns and Polyethylene Terepthalate in conjunction with Mono Ethylene Glycol (MEG). Polyester Fibres/Yarns find application in the production of textiles and films. PTA also finds use in small quantities in the manufacture of paints, etc.




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3.1.2.2.Advantages of Invista T10 Technology: The Invista T 19 technology is a proven and widely used process which provides the following advantages

Consistent mean particle size - helps in better control of operating parameters in downstream process

Less Para-Toluic acid content - leads to better polymerization

Product is suitable for application across all segments of the polyester sector.

3.1.3. Need for Revamp

The markets for polyester fibre and PET resin has almost doubled over the last 10 years and reached nearly 37 million t in 2014. It is projected to grow by approximately 6% CAGR (compound annual growth rate) over the next 10 years. This growth in demand has led to requirement of revamp of PX-PTA plant.

3.1.4. Revamp

3.1.4.1.PX: Paraxylene production of 460 kTPA. The revamp will include addition of new distillation Column, debottlenecking of major equipment including Fired Heaters, Reactors, Fractionators, Combined Feed exchangers, major Vessels.

The Preparation of Process Package and licensing shall be done by the licensor of the unit M/s UOP.

3.1.4.2.PTA: The PTA unit will be revamped to a production capacity of 700 KTPA.

The major revamp activity will involve

Replacement of 21-E1-1607A-D with a shell & tube heat exchanger 21-E1-1607.

PAC Suction Chilling Option

Replacement of the CTA Drier

Apart from above debottlenecking of exchangers, vessels, columns and their internals will be carried out.




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4. RRA METHODOLOGY

The main objective of risk assessment study is to propose a comprehensive but simple approach to carry out risk analysis and conducting feasibility studies for industries, planning and management of industrial prototype hazard analysis study in Indian context.

Risk analysis and risk assessment shall provide details on Risk Assessment techniques used to determine risk posed to people who work inside or live near hazardous facilities, and to aid in preparing effective emergency response plans by delineating a Disaster Management Plan (DMP) to handle on-site and off-site emergencies. Hence, RA is an invaluable method for making informed risk based process safety and environmental impact planning decisions, as well as being fundamental to any decisions while siting a facility. RA is a site or risk specific assessment which is complex and needs extensive study shall involve process understanding, hazard identification, consequence modelling, probability data, vulnerability models/data, local weather and terrain conditions and local population data.

RA may be carried out to serve the following objectives.

Identification of safety areas

Identification of hazard sources

Generation of accidental release scenarios for escape of hazardous materials from the facility

Identification of vulnerable units with recourse to hazard indices

Estimation of damage distances for the accidental release scenarios with recourse to Maximum Credible Accident (MCA) analysis

Estimation of probability of occurrences of hazardous event through fault tree analysis and computation of reliability of various control paths

Assessment of risk on basis of above evaluation against the risk acceptability criteria relevant to the situation

Suggest risk mitigation measures based on engineering judgement, reliability and risk analysis approaches

Delineation / upgradation of DMP

Safety Reports: with external safety report/ occupational safety report,

The risk assessment report covers the following in terms of extent of damage with resource to MCA analysis and delineation of risk mitigations measures with an approach to DMP.

Hazard identification – identification of hazardous activities, hazardous materials, past accident records, etc.

Hazard quantification – consequence analysis to assess the impacts




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Risk presentation

Risk mitigation measures

Disaster management plans

Figure 1: Risk Assessment – Conceptual Framework

Methods of risk prediction shall cover all the design intentions and operating parameters to quantify risk in terms of probability of occurrence of hazardous events and magnitude of its consequence.




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Figure 2: RRA Study Flow

Introduction to Study

Data Collection and discussion with IOCL

Data Input into Risk Analysis

Consequence and Risk Assessment of identified LOC Scenarios

Risk Presentation and Recommendations




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Figure 3: RRA Methodology

4.1. Hazards Identification

4.1.1. Enumeration and Selection of Incidents

Effective management of a Risk Assessment study requires enumeration and selection of incidents or scenarios. Enumeration attempts to ensure that no significant incidents are overlooked; selection tries to reduce the incident outcome cases studied to a manageable number.




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These incidents can be based on:

Loss of containment (LOC) of the materials

Unfortunately, there are infinite ways (incidents) by which loss of containment can occur. For example, leakages of process materials can be of any size, from a pinhole up to a severed pipeline or ruptured vessel. An explosion can occur in either a small container or a large container and, in each case, it can range from a small "puff" to a catastrophic detonation.

A technique commonly used to generate an incident list is to consider potential leaks and major releases from fractures of all process pipelines and vessels. This compilation should include all pipe work and vessels in direct communication, as these may share a significant inventory that cannot be isolated in an emergency. The data generated is as shown below:

Vessel number, description, and dimensions

Materials present

Vessel conditions (phase, temperature, pressure)

Inventory and connecting piping and piping dimensions

The goal of selection is to limit the total number of incident outcome cases, to be studied to a manageable size, without introducing bias or losing resolution through overlooking significant incidents or incident outcomes. The purpose of incident selection is to construct an appropriate set of incidents for the study from the Initial list that has been generated by the enumeration process. An appropriate set of incidents is the minimum number of incidents needed to satisfy the requirements of the study and adequately represent the spectrum of incidents enumerated.

4.2. Characterising the Failures

Accidental release of flammable materials can result in severe consequences. Delayed ignition of flammable vapours can result in blast overpressures covering large areas. This may lead to extensive loss of life and property. In contrast, fires have localized consequences. In most of the cases, fires can be put out or contained, but there are very few mitigating actions that one can take once a vapour cloud has been released.

Among the facilities, the main hazards arise due to the possible leakage of flammable materials. To formulate a structured approach to identification of hazards, an understanding of contributory factors is essential.

4.3. Operating Parameters

Operating parameters (Temperature, Pressure & Phase) may vary subject to the processing, storage, handling, loading or unloading and transportation conditions. Potential vapour release of the materials handled depends significantly on these conditions. Temperature and pressure conditions provided by IOCL have been used for Consequence Analysis.




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4.4. Inventory

Inventory Analysis is commonly used in understanding the relative hazards and short listing of release scenarios. Inventory plays an important role with regard to the potential hazard. A practice commonly used to generate an incident list is to consider potential leaks and major releases from fractures of pipelines and vessels containing sizable inventories. The potential vapour release (source strength) depends upon the quantity of liquid release, the properties of the materials and the operating conditions (pressure, temperature).

4.5. Loss of Containment

Inventory can be discharged into the environment due to Loss of Containment. Various causes and modes for such an eventuality have been described. Certain features of materials to be handled at the facility need to be clearly understood to firstly list out all significant release cases and then to short list release scenarios for a detailed examination.

Inventory release can be either instantaneous or continuous. Failure of a vessel leading to an instantaneous outflow assumes the sudden appearance of such a major crack that practically all of the contents above the crack shall be released in a very short time. The more likely event is the case of inventory release from a hole in a pipe connected to the vessel. The flow rate will depend on the size of the hole as well as on the pressure in front of the hole, prior to the accident. Such pressure is dependent on the pressure in the system.

For a liquid release, the vaporization of released liquid depends on the vapour pressure and weather conditions. Such consideration and others have been kept in mind while performing calculations.

5. CONSEQUENCE ANALYSIS

5.1. Weather Conditions

The consequences arising out of the release of chemicals are dependent on certain things on the prevailing

meteorological conditions. This section describes the influence of these conditions.

Stability Class

Dispersion of gases or vapours largely depends upon the Atmospheric Stability Class.

Table 1 : Pasquill’s Atmospheric stability class

A Very Unstable

B Unstable

C Slightly Unstable




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D Neutral

E Stable

F Very Stable

The stability class for a particular location is generally dependent upon:

Time of the Day (Day or Night)

Cloud Cover

Season

Wind Speed

Six stability classes from A to F are defined while wind speed can take any one of numerous values. It may

thus appear that a large number of outcome cases can be formulated by considering each one of very

many resulting stability class-wind speed combinations. However in fact the number of stability class - wind

speed combinations that needs to be considered for formulating outcome cases in any analysis is very

limited. This is because, in nature, only certain combinations of stability class and wind speed occur. Thus,

for instance combinations such as A-3 m/s or B-5 m/s or F-4 m/s do not occur in nature. As a result only

one or two stability class - wind speed combinations need to be considered to ensure reasonable

completeness of Risk Assessment study. Furthermore, though wind speeds less than 1 m/s may occur in

practice, none of the available dispersion models, including state-of-art ones, can handle wind speeds

below 1 m/s. Fortunately, wind speed does not influence consequences as much as stability class and for

a given stability class, the influence of wind speed is relatively less. On the other hand, consequences vary

considerably with stability class for the same speed.

Except during the monsoon months little or no cloud cover along with the prevailing low wind velocities

results in unstable conditions during the day (C or D) and highly stable conditions (E or F) at night.

During the three months of monsoons, the wind velocities are generally higher and cloud cover generally

present. This results in stability class of D during the day and E or F during the night.

The following wind velocity/ stability class combinations & frequencies are used for Risk Assessment.

D – 2 m/s

F – 1 m/s




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5.2. Hazards associated with Flammable Materials

Fire and explosion hazards depend on the range of flammable concentrations of the material in air among

all common gaseous fuels. Any spillage or loss of containment of heavier hydrocarbons may create a highly

flammable pool of liquid around the source of release. High entrainment of gas phase in the liquid phase

can lead to jet fires. If released at temperatures higher than the normal boiling point they can flash

significantly.

5.3. Damage Criteria

In consequence analysis, use is made of a number of calculation models to estimate the physical effects

of an accident (spill of hazardous material) and to predict the damage (lethality, injury, material destruction)

of the effects. The calculations can roughly be divided in three major groups:

Determination of the source strength parameters;

Determination of the consequential effects;

Determination of the damage or damage distances.

5.4. Source Strength Parameters

Calculation of the outflow of liquid out of equipment or tank or pipe, in case of rupture.

Calculation, in case of liquid outflow, of the instantaneous flash evaporation and of the dimensions of the remaining liquid pool.

Calculation of the evaporation rate, as a function of volatility of the material, pool dimensions and wind velocity.

Source strength equals pump capacities, etc. in some cases of pump discharge line ruptures for catastrophic cases.

5.5. Consequential Effects

Dispersion of gaseous material in the atmosphere as a function of source strength, relative density of the gas, weather conditions and topographical situation of the surrounding area.

Intensity of heat radiation [in kW/m2] due to a fire, as a function of the distance to the source.

Energy of vapour cloud explosions [in N/m2], as a function of the distance to the distance of the exploding cloud.

Concentration of gaseous material in the atmosphere, due to the dispersion of evaporated chemical. The latter can be either explosive or toxic.




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It may be obvious, that the types of models that must be used in a specific risk study strongly depend upon the type of material involved:

Gas, vapour, liquid, solid

Inflammable, explosive,

Stored at high/ low temperatures or pressure

Controlled outflow (pump Inventory) or catastrophic failure

5.6. Selection of Damage Criteria

The damage criterion gives the relation between extent of the physical effects (exposure) and the

percentage of the people that will be killed or injured due to those effects. The knowledge about these

relations depends strongly on the nature of the exposure. In Consequence Analysis studies, in principle

two types of exposure to hazardous effects are distinguished:

1. Heat radiation, from a jet, pool fire, fire ball or flash fire.

2. Vapour Cloud Explosion

5.7. Heat Radiation

The consequences caused by exposure to heat radiation are function of:

The radiation energy onto the human body [kW/m2];

The exposure duration [sec];

The protection of the skin tissue (clothed or naked body).

The limits for 1% of the exposed people to be fatal due to heat radiation, and for second-degree burns are given in the table below:

Table 2 : Damages to Human Life Due to Heat Radiation

Exposure Duration

Radiation energy (1%

lethality, kW/m2

Radiation energy for 2nd degree burns,

kW/m2

Radiation energy for first degree burns, kW/m2

10 Sec 21.2 16 12.5

30 Sec 9.3 7.0 4.0

Reference: TNO purple book




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Since in practical situations, only the people outside will be exposed to heat radiation. In case of a fire, it is reasonable to assume the protection by clothing. It can be assumed that people would be able to find a cover or a shield against thermal radiation in 10-sec. time. Furthermore, 100% lethality may be assumed for all people suffering from direct contact with flames, such as the pool fire, a flash fire or a jet flame. The effects due to relatively lesser incident radiation intensity are given below:

Table 3 : Radiation intensity

Radiation Level

(KW/m2)

Damage to Equipment

Damage to People

1.6 - Will cause no discomfort to long exposure

4.0 Causes pain if duration is longer than 20sec.

But blistering is unlikely.

12.5 Minimum energy to ignite wood with a flame; melts

plastic tubing.

1%lethality in one minute. First degree burns in 10sec.

37.5 Sufficient to cause damage to process

equipment

100%lethalityin1min.

50%lethalityin20sec.

1%lethalityin10sec.

Reference: TNO purple book

The actual results would be less severe due to the various assumptions made in the models arising out of the flame geometry, emissivity, angle of incidence, view factor and others. Upon ignition, a spilled liquid would burn in the form of a large turbulent diffusion flame. The size of the flame would depend upon the spill surface and the thermo-chemical properties of the spilled liquid. In particular, the diameter of the fire (if not confined to a dyke), the visible height of the flame, the tilt and drag of the flame due to wind can be correlated to the burning velocity of the liquid. The radiative output of the flame would be dependent upon the fire size, extent of mixing with air and the flame temperature. Some fraction of the radiation is absorbed by carbon dioxide and water vapour in the intervening atmosphere. In addition, large pool fires produce thick smoke, which can significantly obscure flame radiation. Finally the incident flux at an observer location would depend upon the radiation view factor, which is a function of the distance from the flame surface, the observer’s orientation and the flame geometry.

Estimation of the thermal radiation hazards from pool/ jet fires essentially involves 3 steps;

characterization of flame geometry,

approximation of the radiative properties of the fire and




Page 23 of 98

Calculation of safe separation distances to specified levels of thermal radiation.

5.8. Explosion

In case of vapour cloud explosion, two physical effects may occur:

flash fire over the whole length of the explosive gas cloud;

A blast wave, with typical peak overpressures circular around ignition source.

As explained above, 100% lethality is assumed for all people who are present within the cloud proper.

For the blast wave, the lethality criterion is based on:

Peak overpressure of 0.1 bars will cause serious damage to 10% of the housing/structures.

Falling fragments will kill one of each eight persons in the destroyed buildings.

The following damage criteria may be distinguished with respect to the peak overpressures resulting from a blast wave:

As per approved design basis impact criteria for over pressure (Explosion, BLEVE, and VCE) is 0.35 bar for 30% fatality & 0.5 for 100% fatality is considered.

Table 4 : Damage Due To Overpressures

Peak Overpressure, bar

Damage Type

0.83 Total destruction

0.30 Heavy damage, nearly complete destruction of houses

0.27 Cladding of light industrial building ruptures

0.2 Steel frame buildings distorted and pulled from foundations

0.16 Lower limit of serious structural damage

0.14 Partial collapse of walls and roofs of houses

0.027 Limited minor structural damage

0.01 Typical pressure of glass breakage

Reference: DNV Help file




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From this, it may be concluded that p = 0.17 E+5 pa corresponds approximately with 1% lethality. Furthermore, it is assumed that everyone inside an area in which the peak overpressure is greater than 0.17 E+5 pa will be wounded by mechanical damage. For the gas cloud explosion this will be inside a circle with the ignition source as its centre.

5.9. Consequence Analysis

The consequence results show results of difference accident scenarios. Following are the potential loss of containment scenarios (LOC) envisages in the IOCL expansion scenario.

Table 5: LOC Scenarios Identified in the Study

IS UNIT EQUIPMENT 1 DHDT Feed Surge Drum 2 DHDT Feed Pumps 3 DHDT HDS reactor 4 DHDT Hot H.P Separator 5 DHDT HP amine absorber KOD 6 DHDT Recycle Gas Compressor 7 DHDT Stripper 8 DHDT Stripper Reflux Pump 9 DHDT Hydrotreated Diesel Pumps 10 DHDT Stabilizer Reflux pump 11 DHDT Stabilizer Reflux Drum 12 DHDT Stripper Reflux Drum 13 HGU Raw Naphtha Surge Drum 14 HGU Naphtha Feed pump 15 HGU Raw Naphtha Pump 16 HGU Stripper Overhead separator 17 HGU 2nd Hydrogenator 18 SWS Knock out drum 19 ARU Flash column 20 SRU Acid Gas K.O Drum 21 PTA PX to feed line 22 PTA HP solvent line 23 PTA Reactor 24 PTA HP solvent pump 25 PTA Entrainer storage vessel 26 PTA Methyl Acetate surge drum 27 PTA H2 compressor 28 PTA Outlet line 29 PTA Methyl Acetate release




Page 25 of 98

30 PTA Dissolver Reactor BD/PSV 31 PX Raffinate Rundown Cooler 32 PX Charge Pumps 33 PX Stripper Overhead Pump 34 PX Toluene Column 35 PX Charge Pumps 36 PX Benzene Toluene Splitter 37 PX Benzene Toluene Pumps

The sudden release of hydrocarbon can result in a number of accident situation. As large numer of failure cases can lead to the same type of sequence, representative failure cases are selected for this analysis. The failure cases are based on conservative assumption and engineering judgement. Typically, failure models are considered for 100% pipe dimeter/catastrophic rupture of vessels for rupture and 10% leak (hole size max 10 mm for vessels, based on the guidelines of CPR 18 E.




Page 26 of 98

Table 6: Flammable Results

IS Ref. Unit

Flammable Results

Flash Fire Envelope Radiation Effects: Fire ball Ellipse

Pool Radius (m)

Radiation Effects: Pool Fire Ellipse

Radiation Effects: Jet Fire Ellipse

Furthest Distance in meters

Radiation Distance in meters


Radiation Distance in meters Extent Levels Levels Levels

in ppm 1F 2D (kW/m2) 1F 2D (kW/m2) 1F 2D (kW/m2) 1F 2D

IS-001

DHDT

50% 172.4 167.7 4.7 N/A N/A

21.9

4.7 46.7 54.0 4.7 N/A N/A 100% 129.7 125.3 6.3 N/A N/A 6.3 37.2 42.9 6.3 N/A N/A

- - - 12.5 N/A N/A 12.5 23.7 23.9 12.5 N/A N/A - - - 37.5 N/A N/A 37.5 NR NR 37.5 N/A N/A

IS-002

50% 162.4 170.5 4.7 N/A N/A

N/A

4.7 N/A N/A 4.7 102.7 97.0 100% 84.2 83.4 6.3 N/A N/A 6.3 N/A N/A 6.3 96.1 90.2

- - - 12.5 N/A N/A 12.5 N/A N/A 12.5 83.6 77.4 - - - 37.5 N/A N/A 37.5 N/A N/A 37.5 70.0 63.6

IS-003

50% 38.3 36.7 4.7 N/A N/A

N/A

4.7 N/A N/A 4.7 32.6 32.9 100% 18.7 17.9 6.3 N/A N/A 6.3 N/A N/A 6.3 30.3 30.8

- - - 12.5 N/A N/A 12.5 N/A N/A 12.5 25.6 26.4 - - - 37.5 N/A N/A 37.5 N/A N/A 37.5 NR NR

IS-004

50% 306.0 321.4 4.7 N/A N/A

34.3

4.7 157.1 173.6 4.7 217.6 198.9 100% 149.5 150.9 6.3 N/A N/A 6.3 143.8 158.4 6.3 203.3 185.1

- - - 12.5 N/A N/A 12.5 126.9 134.7 12.5 176.2 159.1 - - - 37.5 N/A N/A 37.5 NR NR 37.5 146.8 130.8

IS-005

50% 162.0 171.1 4.7 N/A N/A

N/A

4.7 N/A N/A 4.7 101.4 95.9 100% 87.8 87.3 6.3 N/A N/A 6.3 N/A N/A 6.3 94.8 89.1


IS-006 50% 162.7 171.3 4.7 N/A N/A

N/A 4.7 N/A N/A 4.7 102.8 97.1

100% 86.4 85.5 6.3 N/A N/A 6.3 N/A N/A 6.3 96.2 90.3




Page 27 of 98

IS Ref. Unit

Flammable Results


Pool Radius (m)







in ppm 1F 2D (kW/m2) 1F 2D (kW/m2) 1F 2D (kW/m2) 1F 2D - - - 12.5 N/A N/A 12.5 N/A N/A 12.5 83.7 77.5 - - - 37.5 N/A N/A 37.5 N/A N/A 37.5 70.1 63.7

IS-007

50% 205.2 211.9 4.7 N/A N/A

N/A

4.7 N/A N/A 4.7 116.2 109.7 100% 94.2 93.7 6.3 N/A N/A 6.3 N/A N/A 6.3 108.7 102.0


IS-008

50% 108.4 77.4 4.7 N/A N/A

30.1

4.7 88.9 99.9 4.7 67.3 68.9 100% 60.6 35.2 6.3 N/A N/A 6.3 76.4 85.9 6.3 63.0 64.0

- - - 12.5 N/A N/A 12.5 60.3 63.7 12.5 54.9 54.9 - - - 37.5 N/A N/A 37.5 NR NR 37.5 45.9 44.9

IS-009

50% 86.4 87.6 4.7 N/A N/A

N/A

4.7 88.9 99.9 4.7 58.2 54.8 100% 37.9 37.4 6.3 N/A N/A 6.3 76.4 85.9 6.3 54.5 51.0

- - - 12.5 N/A N/A 12.5 60.3 63.7 12.5 47.6 44.0 - - - 37.5 N/A N/A 37.5 NR NR 37.5 40.0 36.3

IS-010

50% 26.4 32.0 4.7 N/A N/A

4.8

4.7 44.3 47.7 4.7 24.6 23.3 100% 15.4 17.4 6.3 N/A N/A 6.3 39.8 44.4 6.3 23.1 21.7

- - - 12.5 N/A N/A 12.5 30.0 36.5 12.5 20.2 18.7 - - - 37.5 N/A N/A 37.5 23.6 25.9 37.5 17.0 15.4

IS-011

50% 102.5 96.2 4.7 N/A N/A

22.4

4.7 49.6 58.5 4.7 N/A N/A 100% 61.0 60.3 6.3 N/A N/A 6.3 39.9 47.1 6.3 N/A N/A


IS-012 50% 76.4 71.0 4.7 N/A N/A

22.8 4.7 49.6 58.0 4.7 N/A N/A

100% 33.9 33.4 6.3 N/A N/A 6.3 39.8 46.5 6.3 N/A N/A




Page 28 of 98

IS Ref. Unit

Flammable Results


Pool Radius (m)







in ppm 1F 2D (kW/m2) 1F 2D (kW/m2) 1F 2D (kW/m2) 1F 2D - - - 12.5 N/A N/A 12.5 26.2 27.2 12.5 N/A N/A - - - 37.5 N/A N/A 37.5 NR NR 37.5 N/A N/A

IS-013

HGU

50% 112.9 105.2 4.7 N/A N/A

22.8

4.7 49.4 57.8 4.7 N/A N/A 100% 70.9 65.4 6.3 N/A N/A 6.3 39.3 45.5 6.3 N/A N/A


IS-014

50% 144.5 157.3 4.7 N/A N/A

N/A

4.7 N/A N/A 4.7 84.7 80.4 100% 79.1 79.4 6.3 N/A N/A 6.3 N/A N/A 6.3 79.3 74.8

- - - 12.5 N/A N/A 12.5 N/A N/A 12.5 69.2 64.3 - - - 37.5 N/A N/A 37.5 N/A N/A 37.5 NR NR

IS-015

50% 114.0 113.7 4.7 N/A N/A

13.7

4.7 42.0 55.8 4.7 N/A N/A 100% 60.4 68.2 6.3 N/A N/A 6.3 34.7 47.5 6.3 N/A N/A


IS-016

50% 64.3 76.2 4.7 N/A N/A

8.8

4.7 50.7 57.3 4.7 65.7 62.4 100% 33.7 35.3 6.3 N/A N/A 6.3 44.8 51.5 6.3 61.6 58.1

- - - 12.5 N/A N/A 12.5 33.1 37.5 12.5 53.7 49.9 - - - 37.5 N/A N/A 37.5 NR NR 37.5 45.0 40.8

IS-017

50% 31.4 30.1 4.7 N/A N/A

N/A

4.7 N/A N/A 4.7 28.4 28.6 100% 14.5 14.0 6.3 N/A N/A 6.3 N/A N/A 6.3 26.6 26.9


IS-021 PTA 50% 14.0 14.0 4.7 77 77

N/A 4.7 75.3 75.3 4.7 69.3 77.0

100% 28.0 28.0 6.3 N/A N/A 6.3 N/A N/A 6.3 67.5 75.0




Page 29 of 98

IS Ref. Unit

Flammable Results


Pool Radius (m)







in ppm 1F 2D (kW/m2) 1F 2D (kW/m2) 1F 2D (kW/m2) 1F 2D - - - 12.5 61.2 61.2 12.5 48.0 48.0 12.5 54.0 60.0 - - - 37.5 51.6 51.6 37.5 NR NR 37.5 46.4 51.6

IS-022

50% 12.6 12.6 4.7 N/A N/A

N/A

4.7 102.7 114.1 4.7 68.9 76.6 100% 25.2 25.2 6.3 N/A N/A 6.3 87.3 97.0 6.3 58.6 65.1

- - - 12.5 N/A N/A 12.5 59.0 65.5 12.5 54.0 60.0 - - - 37.5 N/A N/A 37.5 NR NR 37.5 46.4 51.6

IS-023

50% 14.0 14.0 4.7 N/A N/A

N/A

4.7 67.5 75.0 4.7 67.8 75.3 100% 28.0 28.0 6.3 N/A N/A 6.3 57.4 63.8 6.3 57.6 64.0

- - - 12.5 N/A N/A 12.5 43.2 48.0 12.5 55.1 61.2 - - - 37.5 N/A N/A 37.5 NR NR 37.5 46.4 51.6

IS-024

50% 12.5 12.5 4.7 N/A N/A

N/A

4.7 65.2 72.4 4.7 68.9 76.6 100% 25.0 25.0 6.3 N/A N/A 6.3 55.4 61.5 6.3 58.6 65.1

- - - 12.5 N/A N/A 12.5 47.1 52.3 12.5 59.0 65.5 - - - 37.5 N/A N/A 37.5 NR NR 37.5 NR NR

IS-025

50% 1.3 1.3 4.7 N/A N/A

N/A

4.7 9.0 10.0 4.7 13.1 14.6 100% 2.5 2.5 6.3 N/A N/A 6.3 7.7 8.5 6.3 11.2 12.4

- - - 12.5 N/A N/A 12.5 5.9 6.5 12.5 NR NR - - - 37.5 N/A N/A 37.5 NR NR 37.5 NR NR

IS-026

50% 48.9 48.9 4.7 N/A N/A

N/A

4.7 110.7 123.0 4.7 NR NR 100% 97.8 97.8 6.3 N/A N/A 6.3 94.1 104.6 6.3 NR NR

- - - 12.5 N/A N/A 12.5 64.8 72.0 12.5 NR NR - - - 37.5 N/A N/A 37.5 34.0 34.0 37.5 NR NR

IS-027 50% 18.9 18.9 4.7 N/A N/A

N/A 4.7 NA NA 4.7 NA 32.9

100% 37.7 37.7 6.3 N/A N/A 6.3 NA NA 6.3 NA 29.6




Page 30 of 98

IS Ref. Unit

Flammable Results


Pool Radius (m)







in ppm 1F 2D (kW/m2) 1F 2D (kW/m2) 1F 2D (kW/m2) 1F 2D - - - 12.5 N/A N/A 12.5 NA NA 12.5 NA 23.7 - - - 37.5 N/A N/A 37.5 NA NA 37.5 NA 16.4

IS-028

50% 11.9 12.6 4.7 N/A N/A

N/A

4.7 50.3 117 4.7 72.7 76.6 100% 23.8 25.2 6.3 N/A N/A 6.3 25.7 86.7 6.3 61.1 65.5

- - - 12.5 N/A N/A 12.5 NR 75 12.5 NR NR - - - 37.5 N/A N/A 37.5 NR 68.7 37.5 NR NR

IS-029

50% 10.0 14.0 4.7 N/A N/A

N/A

4.7 NA NA 4.7 NA 76.6 100% 20.0 28.0 6.3 N/A N/A 6.3 NA NA 6.3 61.1 65.5

- - - 12.5 N/A N/A 12.5 NA NA 12.5 NR NR - - - 37.5 N/A N/A 37.5 NA NA 37.5 NR NR

IS-030

50% 7.0 8.0 4.7 N/A N/A

N/A

4.7 NA NA 4.7 14 14 100% 14.0 16.0 6.3 N/A N/A 6.3 NA NA 6.3 10 10

- - - 12.5 N/A N/A 12.5 NA NA 12.5 NR NR - - - 37.5 N/A N/A 37.5 NA NA 37.5 NR NR

IS-031

PX

50% 28.0 20.0 4.7 N/A N/A

N/A

4.7 46.6 53.2 4.7 NA NA 100% 56.0 40.0 6.3 N/A N/A 6.3 19.4 20 6.3 NA NA

- - - 12.5 N/A N/A 12.5 NR NR 12.5 NA NA - - - 37.5 N/A N/A 37.5 NR NR 37.5 NA NA

IS-032 50% 16.8 15.4 4.7 N/A N/A

N/A 4.7 57.7 62.8 4.7 68.3 64.8

100% 33.5 30.8 6.3 N/A N/A 6.3 34.1 35.7 6.3 54.1 50.1 - - - 37.5 N/A N/A 37.5 NR NR 37.5 45.4 41.1

IS-033 50% 26.4 32.0 4.7 N/A N/A

NA 4.7 44.3 47.7 4.7 24.6 23.3

100% 15.4 17.4 6.3 N/A N/A 6.3 39.8 44.4 6.3 23.1 21.7




Page 31 of 98

IS Ref. Unit

Flammable Results


Pool Radius (m)







in ppm 1F 2D (kW/m2) 1F 2D (kW/m2) 1F 2D (kW/m2) 1F 2D - - - 37.5 N/A N/A 37.5 23.6 25.9 37.5 17.0 15.4

IS-034 50% 48.2 33.5 4.7 N/A N/A

NA 4.7 54.6 61.9 4.7 NA NA

100% 106.0 73.8 6.3 N/A N/A 6.3 24 23.7 6.3 NA NA - - - 37.5 N/A N/A 37.5 NR NR 37.5 NA NA

IS-035 50% 22.7 23.7 4.7 N/A N/A

NA 4.7 49.5 55.1 4.7 61.5 59.5

100% 49.9 52.1 6.3 N/A N/A 6.3 25.3 27.2 6.3 49.3 46.5 - - - 37.5 N/A N/A 37.5 NR NR 37.5 41.6 38.5

IS-036 50% 22.7 23.7 4.7 N/A N/A

NA 4.7 26 25 4.7 20.4 19.2

100% 49.9 52.1 6.3 N/A N/A 6.3 23.8 21.3 6.3 16.4 15.1 - - - 37.5 N/A N/A 37.5 21.4 18.1 37.5 13.9 12.5

IS-037 50% 6.8 3.6 4.7 N/A N/A

NA 4.7 151 423 4.7 NA NA

100% 15.0 8.0 6.3 N/A N/A 6.3 146 419 6.3 NA NA - - - 37.5 N/A N/A 37.5 142 417 37.5 NA NA

Note: Consequence results doesn’t include depressurization case as it’s having very low inventory and software doesn’t give any results for the

same.




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Table 7: Summary of Toxic Dispersion Results

IS Ref. Hole size (mm)

Release rate (kg/s)

Toxic Results Unit

IDLH ppm Distance in meters 1F 2D

IS-018 CR NA 100 281.3 212.3 SWS IS-019 20 0.05 100 259 161.5 ARU IS-020 CR NA 100 287.7 218.9 SRU

Table 8: Summary of Overpressure Explosion Results

IS Ref. Hole size (mm)

Release rate (kg/s)

Explosion Results

Unit Over Pressure Levels

Over-pressure (bar) Distance in meters

1F 2D

IS-002 20 26.8 0.05 327.5 329

DHDT

0.2 209.8 217.3 0.7 179.7 188.7

IS-003 10 3.48 0.05 75.6 72.8 0.2 43.6 42.7 0.7 35.4 35

IS-004 50 140.5 0.05 619.6 631.1 0.2 395 412.5 0.7 337.5 356.5

IS-006 20 26.4 0.05 330.2 329.8 0.2 210.6 217.5 0.7 180 188.8

IS-007 50 36.5 0.05 390 390.2 0.2 256.5 263.6 0.7 222.3 231.1

IS-008 20 8.9 0.05 216 161.5 0.2 134.5 97.2 0.7 113.6 80.7

IS-009 20 8 0.05 164.4 160 0.2 105.1 103.8 0.7 89.9 89.4

IS-014 20 13.3 0.05 309.2 301.1

HGU

0.2 190.3 194.9 0.7 159.9 167.7

IS-016 20 6.1 0.05 138.2 151.4 0.2 83.3 94.2 0.7 69.2 79.6




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6. RISK ASSESSMENT

The output from the consequence analysis, and the frequency analysis, along with other supporting

information are combined in a ‘risk model’. The following data utilized for risk calculation are:

Event frequencies

Consequence data

Ignition probabilities

Population numbers and distribution in the plant.

Local Weather data

6.1. Ignition Sources

In order for a fire or explosion to start there must be an ignition source of sufficient heat intensity to cause

an ignition. Ignition causes a release of flammable liquid or gas to become a fire (jet fire, flash fire, pool fire

etc.) or explosion. There are many possible sources of ignition and those that are most likely will depend

on the release scenario. Sources of ignition include electrical sparks, static electricity, naked flames, hot

surfaces, impact, friction, etc. The following Ignition sources identified in a RRA under several categories

including:

Hot Surfaces – unlagged surfaces on hot equipment can act as sources of ignition;

Current Electricity – electrical equipment and cables can act as sources of ignition if sparks are generated at contact points or where wires overheat; e.g. Electrical equipment sparking

Static Electricity – static electricity can build up on any unearthed equipment and generate sparks. Static is commonly found on vehicles, vessels handling particulate solids and manned areas with nonconductive floor or footwear unearthed floors; e.g. Electrostatic discharges.

Naked Flames – all naked flames (including cigarettes) are potential sources of ignition; this category also includes welding, flame-cutting and other hot work, fired furnaces and flares; e.g. Open flame heaters (boilers and flame heaters)

Friction – equipment with moving parts in contact can generate heat through friction if not properly lubricated. This includes all rotating equipment and cold cutting devices such as drills, lathes and saws; Mechanical sparking

Impact – impact between hard surfaces, particularly metal-to-metal contact, can generate sparks. This includes lifted objects lowered to a metal floor too quickly and the use of hand tools such as hammers; and




Page 34 of 98

Chemical ignition – some chemicals can spontaneously ignite if exposed to air, while oxidizing agents such as oxygen gas and peroxides can cause flammable materials to ignite at ambient temperatures.

6.2. Site Location and Vicinity

The site is located about 110 Kms. from Delhi at 29°30’N Latitude & 76°52’ E Longitude at an elevation of 237 m amsl and spreads over 756 acres.

In the surroundings of the Panipat refinery site, there are no villages in very close proximity. The population of village Baholi near the refinery was shifted by Govt. of Haryana and thereafter, the density of population in this area became very thin.

Figure 4: Site Location

6.3. Population Data

The population, which may be exposed to certain amount of risk due to hazards present in the refinery, is

IOCL personnel working in the refinery complex and the general population living in the vicinity of the

complex.




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Onsite as well as offsite population data mentioned in the following table. This data was utilized for two

purposes, firstly to estimate the Individual Risk of fatality for a member of each onsite group, and also as

the population input for calculating societal risk for site personnel.

Table 9 : Occupancy Data

Sl. No

Type of building Shift Blast-proof construction

Positive pressurization General A B C

1 Polymer Laboratory 27 15 15 15 NO YES 2 Product warehouse 15 10 10 10 NO YES 3 Security Building 5 1 1 1 NO NO 4 OC / Maintenance Cabin-07 1 7 7 7 NO NO 5 SRR (Swing) 10 2 2 2 YES YES 6 Extruder OC - 2 2 2 YES NO 7 Sub Station-5 4 1 1 1 NO YES 8 Operator Cabin-06 7 0 0 0 NO NO 9 Sub Station-6 5 9 9 9 NO NO 10 Extruder Rack Room - 1 1 1 NO YES 11 Central Store 20 2 2 1 NO NO 12 Telephone Exchange 5 - - - NO NO 13 Project Office -02 30 - - - NO NO 14 Project Office -01 25 - - - NO NO 15 Canteen 20 10 10 - NO NO 16 Cafeteria - - - - 17 Admin Building 268 - - - NO YES 18 Training Centre 20 - - - NO YES 19 VAR Bldg - - - - 20 Operator Cabin-03 4 - - - NO NO 21 Control room 10 3 3 2 NO YES 22 Control Room 10 2 2 1 YES YES 23 Maintenance Building & Fire

station , first aid & OHC 25 5 5 5 NO NO

24 Central work shop 25 5 5 5 NO NO 25 Technology Building 50 - - - NO YES 26 Chemical lab 15 5 5 5 YES YES 27 Master Control Room 15 10 10 10 YES YES 28 Local C/R Bldg 4 1 1 1 NO NO 29 Operator Cabin-04 - 2 2 2 NO NO 30 Operator Cabin-05 - 2 2 2 NO NO 31 Local C/R Bldg 7 1 1 1 NO NO

32 CR &Substation 10 5 5 5 YES YES 33 CR & Substation 9 9 9 9 - - 34 OC / FC -1 2 2 2 2 NO NO 35 OC / FC -2 4 4 4 4 NO NO

36 OC / FC -3 4 4 4 4 NO NO 37 Operator cabin -02 0 12 12 12 NO NO




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38 Substation 1 &2 0 1 1 1 YES YES 39 SRR-1 8 2 2 2 YES YES 40 Local C/R Bldg 8 1 1 1 NO NO 41 Control room 5 - - - NO NO 42 Control room (1 no.) and offices(2

no's) 15 4 4 NA YES YES

43 Op. Cabin -01 1 4 4 4 NO NO

44 Tech office/Operator cabin -08 5 1 1 1 NO NO 45 EIL site office - - - - - - 46 Drivers rest room 5 5 5 2 NO NO 47 Gate post - 1 1 1 NO NO 48 SRR-5 14 7 7 7 YES YES

49 Substation-4 4 1 1 1 YES YES 50 Extruder CR 0 1 1 1 NO YES 51 SRR-6 4 - - - YES YES 52 Substation-13 4 2 2 2 YES YES

53 OC 2 5 5 5 NO NO 54 Substation-3 4 1 1 1 YES YES 55 SRR-2 10 1 1 1 YES YES 56 Rair Kalan village - - - - - -

57 Dharam garh - - - - - - 58 Baljattan village - - - - - - 59 SRR-3 8 1 1 1 NO NO

753 170 170 150




Page 37 of 98

6.4. Location Specific Individual Risk (LSIR)

Location Specific Individual Risk (LSIR) is a commonly used risk assessment tool and is defined as the

frequency per year at which an individual, who stays unprotected for 24 hours per day and 365 days per

year at specific location, is expected to sustain fatal harm due to exposure to hazards induced by the project

facility. From the LSIR value, the Individual Risk Per Annum (IRPA) to the personnel based on their

exposure within the project facility.

6.5. Individual Risk Criteria

Individual risk criteria are well established both within industry and by regulatory bodies. The criteria adopted by the UK HSE, which are widely used and considered most appropriate to this study are:

Figure 5: Individual Risk Acceptance Criteria

The “ALARP region” (1X10-3 to 1X10-5) lies between unacceptably high and negligible risk levels. Even if a

level of risk for a “baseline case” has been judged to be in this ALARP region it is still necessary to consider

introducing further risk reduction measures to drive the remaining, or “residual”, risk downwards.

The individual risk contours will not be affected by the number of persons living or working in the area

around the facility. Thus, a person located on the 1.0 x 10-6 individual risk contour for one year has one

chance in a million of being fatally injured by the hazards associated with releases of hazardous fluids,

regardless of how many other persons are located in the same area.




Page 38 of 98

6.6. Risk criteria for Societal Risk

Societal risk is defined as the relationship between the frequency and the number of people suffering a

given level of harm from the realization of specified hazards. It is usually taken to refer to the risk of death,

and usually expressed as a risk per year. In the same way as for individual risk, maximum tolerable and

broadly acceptable criteria are set a upper and lower limits, where between these levels (termed the ALARP

region) risks should be reduced wherever possible.

Societal risk criteria are more judgmental, and therefore less well established, than those for individual risk.

The general aim of such criteria is to balance the risk to population groups from a facility with the benefits

that the group, or society as a whole, receive. The criteria, therefore, may vary according to the type and

value of facility being assessed (where value is not necessarily defined in monetary terms) and the type of

population that may be affected, as well as according to the country and regulatory authority.

(Source: UK HSE Guidelines)

Figure 6: Societal Risk Acceptance Criteria

1.00E-08

1.00E-07

1.00E-06

1.00E-05

1.00E-04

1.00E-03

1.00E-02

1.00E-01

1 10 100 1000 10000 Number of fatalities (N)

Frequency of N or more fatalities (per year)

NEGLIGIBLE

INTOLERABLE

ALARP Region




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7. RISK RESULTS

The risk modelling has been performed using DNV PHAST RISK software. Thereby, the details of the input

data used for the risk modelling such as vulnerability criteria, ignition probability and occupancy data are

as given in the RRA Assumption Register. This chapter focuses on the outcome of the risk results and the

comparison of the risk results with UK HSE risk acceptance criteria.

7.1. Location Specific Individual Risk (LSIR) Results

The LSIR results for the project facility are presented in below figure;

Figure 7: Combined LSIR Contour for Project facility




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Location Specific Individual Risk (LSIR) Contour gives the individual risk due to the identified hazards for the entire population (Off site & On site). The LSIR values for the Plant locations are found to be in the ALARP region.

Table 10: Location Specific Risk Value

Risk Ranking Point Location Specific Individual Risk DHDT UNIT 9.021E-08 OC-1 1.660E-07 OC-4 2.195E-05 SCR-14 1.033E-05 SS NEAR SRU/SWS/ARU 1.665E-05 SULFUR YARD 1.891E-05

Legend:

Unacceptable ALARP (As Low As Reasonably Possible)

Acceptable

The risk results show that IRPA for all worker group of Project Facility fall under the ALARP & Broadly

Acceptable region as per IR Risk Acceptance Criteria.

7.2. Societal Risk

The F-N curve is shown below presents the societal risk for all personnel from the fire and explosion

hazards associated with the plant. The societal risk is presented in terms of cumulative frequency (F) of

occurrence of events that lead to more than (N) number of fatalities.

Combined F-N Curve represents the risk for both day & night conditions. The Green and Yellow lines show

the maximum and minimum risk levels as per UK HSE risk acceptance criteria. The Blue line shows the

combined risk for personnel.




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Figure 8: F-N curve

The F-N curves show that societal risk for the overall population considered falls under broadly acceptable

and ALARP region (10-2 to 10-4) i.e. in the acceptable region.

8. CONCLUSIONS & RECOMMENDATIONS

The study team identified 30 numbers of scenarios for the RRA study. Considering the risk contours and FN curve for combination of all scenarios, DNV- PHAST RISK (SAFETI) software has been used for estimating the risk.

The following interpretations are derived from the risk results of this study:

Individual risk is in the ALARP region of the UK HSE Individual risk acceptance criteria.

The societal risk is in the ALARP region of the UK HSE Societal risk acceptance criteria.

The conclusions based on the RRA study outcome are listed below:

Individual Risk Values at control room, electrical sub-station, workshop, fire station, PSA, security barrack, medical building, administration building, security building are found to be in ALARP region.

This RRA report represents the worst case scenario for all the consequences. Maximum inventory and maximum pressure have been considered as an initial cause for worst case scenario. It was observed that there are no foreseen hazards due to depressurisation after blow down. All consequence would be contained within the unit. Hence report doesn’t take any credit for the blow down. It has been observed that

the consequence results are not having any adverse effects on the adjacent facilities.

Risk is combination of consequence and failure frequency of the scenario. Consequences are found to be higher because of the availability of flammable gas/liquid and high pressure in the process. However the probabilities of the failure are in the acceptable range (1E-4 to 1E-7). Hence the risk falls under As Low As Reasonably Practicable (ALARP) region.




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IR Curve presents the combined risk hazards modelled for facility. The risk is expressed as risk of death on average per year. The largest contour as shown in Dark Green colours represents a risk level of 1E-9 per year while the smallest contour shown in red colour represents an individual risk of 1E-3 year.

The societal risk (F-N Curve) from facility presented in figure shows that societal risk falls in broadly acceptable and ALARP region as per the UK HSE Risk Acceptance Criteria with the fatality of 60 persons in the frequency of E-06.

8.1. Technical Recommendations:

When the Plant is in Operation, Permit system should be introduced for outside visitors’ entry. Also

the number of outside persons at any time within facility should be well regulated.

Functional locations should include detailed and specific description for proper identification of permit area.

Specifications of all Safety Equipment’s shall be based on the detailed specification requested by the respective departments and approved vendors shall alone be used.

The failure frequencies assumed for the RRA are for that of a well-maintained Oil & Gas Facilities as per standard norms. Hence the facility shall be maintained well as per internationally acceptable practices.

Ensure that pressure vessels containing significant quantities of liquefied gas are equipped with water sprinkler system to cool the shell in case of external fire. Subsequently to avoid give away of the vessel.

In order to reduce the failure frequency of critical equipment’s, the following are recommended.

o High head pumps, which are in flammable / toxic services,

Are needed to be identified.

Their seals, instruments and accessories are to be monitored closely

A detailed preventive maintenance plan to be prepared and followed.

o Compressors which are in flammable / toxic liquid services,


Their seals, instruments and accessories are to be monitored closely


o Surge Drums & Reflux drums and critical vessels whose rupture would lead to cascading effect




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Monitoring of vessel internals to be carried out during shut down.


Appropriate Personal Protective equipment (PPE) as per standards shall be used by the personnel working in the area.

Emergency procedures, SOP shall be maintained and followed accordingly.

Safety Audits shall be regularly done as per norms and recommendations of OISD. Risk Analysis Study in future shall be required if there is any change in the plant facility.




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9. REFERENCES

Codes and Standards

PGS 3 Guidelines for RRA by Ministerie van VROM (of Netherlands) – Purple Book- CPR 18 E

OGP Database

IS 15656: Hazard Identification & Risk Analysis – Code of Practice

UK HSE Guidelines




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ANNEXURE – I ISOLATABLE SECTION




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IS UNIT EQUIPMENT 1 DHDT Feed Surge Drum 2 DHDT Feed Pumps 3 DHDT HDS reactor 4 DHDT Hot H.P Separator 5 DHDT HP amine absorber KOD 6 DHDT Recycle Gas Compressor 7 DHDT Stripper 8 DHDT Stripper Reflux Pump 9 DHDT Hydrotreated Diesel Pumps 10 DHDT Stabilizer Reflux pump 11 DHDT Stabilizer Reflux Drum 12 DHDT Stripper Reflux Drum 13 HGU Raw Naphtha Surge Drum 14 HGU Naphtha Feed pump 15 HGU Raw Naphtha Pump 16 HGU Stripper Overhead separator 17 HGU 2nd Hydrogenator 18 SWS Knock out drum 19 ARU Flash column 20 SRU Acid Gas K.O Drum 21 PTA PX to feed line 22 PTA HP solvent line 23 PTA Reactor 24 PTA HP solvent pump 25 PTA Entrainer storage vessel 26 PTA Methyl Acetate surge drum 27 PTA H2 compressor 28 PTA Outlet line 29 PTA Methyl Acetate release 30 PTA Dissolver Reactor BD/PSV 31 PX Raffinate Rundown Cooler 32 PX Charge Pumps 33 PX Stripper Overhead Pump 34 PX Toluene Column 35 PX Charge Pumps 36 PX Benzene Toulene Splitter 37 PX Benzene Toulene Pumps




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ANNEXURE – II – Consequence Results




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Overpressure Contours

DHDT IS-002: Feed Pumps (1F m/s)

2D (m/s)




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IS-003: HDS Reactor 1F (m/s)

2D (m/s)

IS-004: HOT HP Seperator 1F (m/s)




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2D (m/s)

IS-006 – Recycle Gas Compressor 1F (m/s)

(2D m/s)




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IS-007: Stripper 1F (m/s)

(2D m/s)

IS 008: Stripper Reflux Pump 1F (m/s)




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(2D m/s)

IS 009: Hydroteated diesel Pump 1F (m/s)

(2D m/s)




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IS: 014: Naptha Feed Pump 1F (m/s)

(2D m/s)




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IS: 016: Stripper Overhead Separator 1F (m/s)

(2D m/s)




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Jet Fire Contours (1F m/s) IS-2

IS-3




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IS-4

IS-5




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IS-6

IS-7




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IS-8

IS-9




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IS-10

IS-14




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IS-15

IS-16




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IS-17




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Jet Fire Contours (2D m/s) IS-2

IS-3




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IS-4

IS-5




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IS-6

IS-7




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IS-8

IS-9




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IS-10

IS-14




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IS-15

IS-16




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IS-17




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Flash Fire Contours (1F m/s) IS-1

IS-2




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IS-3

IS-4




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IS-5

IS-6




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IS-7

IS-8




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IS-9

IS-10




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IS-11

IS-12




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IS-13

IS-14




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IS-15

IS-16




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IS-17




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Flash Fire Contours (2D m/s) IS-1

IS-2




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IS-3

IS-4




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IS-5

IS-6




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IS-7

IS-8




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IS-9

IS-10




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IS-11

IS-12




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IS-13

IS-14




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IS-15

IS-16




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IS-17




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Pool Fire Contours (1F m/s) IS-1

IS-2




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IS-4

IS-5




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IS-6

IS-8




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IS-10

IS-11




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IS-12

IS-13




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IS-16




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Pool Fire Contours (2D m/s) IS-1

IS-2




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IS-4

IS-5




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IS-6

IS-8




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IS-10

IS-11




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IS-12

IS-13




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IS-16

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