indian oil corporation limited quantitative...

Report No – Polite/IND/2017/IOCL – Raipur Rev No – 01 Date – 12th March 2018

INDIAN OIL CORPORATION LIMITED

Quantitative Risk Assessment

of

LPG Bottling Plant,

Raipur

By

Quantitative Risk Assessment Report

LPG Bottling Plant, Raipur

Polite/IND/2018/IOCL – Raipur || Rev – 00 || Issue: March 2018

| Disclaimer| of 54

DISCLAIMER

M/S Polite Engineering completed this Document on the basis of a defined program of work

and terms and conditions agreed with the Client. We confirm that in preparing this

Document, we have exercised all reasonable skill and care, taking into account the project

objectives, the agreed scope of work, prevailing site conditions and the degree of manpower

and resources allocated to the project.

M/S Polite Engineering accepts no responsibility to any parties whatsoever, following the

issue of the Document, for any matters arising outside the agreed scope of the work.

This Document is issued in confidence to the Client and M/S Polite Engineering has no

responsibility to any third parties to whom this Document may be circulated, in part or in full,

and any such parties rely on the contents of the report solely at their own risk.

Unless specifically assigned or transferred within the terms of the agreement, M/S Polite

Engineering asserts and retains all Copyright, and other Intellectual Property Rights, in and

over the Report and its contents.




| Document Control Sheet| of 54

DOCUMENT CONTROL SHEET

EV. DATE DESCRIPTION PREPARED

BY CHECKED BY APPROVED BY

00 12/03/2018 Issued for Comments Mr. Hemant

Padwal Mr. Madan

Gavhane M/S IOCL

© Copyright Polite Engineering All rights reserved. No part of this document may be reproduced or transmitted in any form or by any means without

permission of the publisher.




| Abbreviations| of 54

ABBREVIATIONS

AIChE American Institute of Chemical Engineers ALARP As Low As Reasonably Practicable IOCL Indian Oil Corporation Limited CCPS Centre of Chemical Process Safety DNV Det Norske Veritas ERDMP Emergency Response and Disaster Management Plan FBR Full Bore Rupture HF Highly Flammable HSD High Speed Diesel HSE Health Safety and Environment IR Individual Risk IRPA Individual Risk per Annum LFL Lower Flammability Level LSIR Location Specific Individual Risk NR Not Reached OGP International Association of Oil and Gas production PHAST Process Hazard Analysis Software tool PLL Potential Loss of Life PNGRB Petroleum and Natural Gas Regulatory Board QRA Quantitative Risk Assessment SKO Superior Kerosene UFL Upper Flammability Level




| Contents | of 54

Contents

32TDisclaimer32T .................................................................................................................................. 2

32TDocument Control Sheet 32T ............................................................................................................ 3

32TAbbreviations 32T ............................................................................................................................. 4

32TDefinitions 32T.................................................................................................................................. 8

32T132T 32TINTRODUCTION32T ........................................................................................................... 10

32T1.132T 32TProject Objective32T ....................................................................................................... 10

32T232T 32TMETHODOLOGY32T .......................................................................................................... 11

32T2.132T 32TMethodology32T ............................................................................................................. 11

32T2.232T 32TQRA Approach32T .......................................................................................................... 11

32T2.2.132T 32TResult Interpretation32T........................................................................................... 11

32T2.2.232T 32TRisk Criteria32T ....................................................................................................... 12

32T2.332T 32TRisk32T............................................................................................................................ 13

32T2.432T 32TIndividual Risk Criteria (IR)32T ..................................................................................... 13

32T2.532T 32TPresentation of Risk Results32T ...................................................................................... 14

32T2.5.132T 32TLocation Specific Individual Risk (LSIR)32T ......................................................... 14

32T2.5.232T 32TIndividual Risk per Annum (IRPA)32T ................................................................... 14

32T2.5.332T 32TPotential Loss of Life (PLL)32T .............................................................................. 14

32T332T 32THAZARD IDENTIFICATION32T ........................................................................................ 15

32T3.132T 32THazards associated with storage tanks 32T ...................................................................... 15

32T3.232T 32THazard Categories 32T ..................................................................................................... 15

32T3.332T 32THazardous Properties 32T................................................................................................. 15

32T3.432T 32TScenarios 32T ................................................................................................................... 16

32T3.4.132T 32TList of identified Scenarios 32T ................................................................................ 17

32T3.532T 32TClimatic Conditions32T................................................................................................... 18




| Contents | of 54

32T3.5.132T 32TMeteorological Data32T........................................................................................... 18

32T3.5.232T 32TAtmospheric Stability Classes 32T ........................................................................... 18

32T432T 32TEVENTS AND IGNITION PROBABILITY32T .................................................................. 20

32T4.132T 32TEvent Tree32T ................................................................................................................. 20

32T4.232T 32TConsequential Events 32T ................................................................................................ 21

32T4.2.132T 32TJet Fire32T ................................................................................................................ 21

32T4.2.232T 32TPool Fire32T ............................................................................................................. 22

32T4.2.332T 32TFlammable Gas Dispersion / Flash Fire32T ............................................................. 22

32T4.332T 32TIgnition Probability32T ................................................................................................... 22

32T532T 32TCONSEQUENCE ANALYSIS 32T ....................................................................................... 24

32T5.132T 32TModes of failure32T ........................................................................................................ 24

32T5.232T 32TImpact Criteria32T........................................................................................................... 25

32T5.2.132T 32TPersonnel 32T ............................................................................................................ 25

32T5.332T 32TInitial Release Rates 32T .................................................................................................. 26

32T5.432T 32TFlammable Gas Dispersion 32T ....................................................................................... 26

32T5.532T 32TRadiation Distances due to Jet Fire32T ........................................................................... 34

32T5.632T 32TRadiation Distances due to Pool Fire32T ........................................................................ 40

32TRadiation Distances due to Fireball 32T ..................................................................................... 42

32T632T 32TLIKELIHOOD ESTIMATION32T ........................................................................................ 45

32T6.132T 32TFailure Frequencies 32T ................................................................................................... 45

32T732T 32TRISK ANALYSIS 32T ............................................................................................................ 47

32T7.132T 32TRisk Contours32T ............................................................................................................ 47

32T7.232T 32TFN Curve32T ................................................................................................................... 49

32T7.332T 32TIRPA and PLL32T ........................................................................................................... 49

32T7.432T 32TConclusion32T ................................................................................................................. 49




| Contents | of 54

32T7.532T 32TRecommendations 32T ..................................................................................................... 50

32T832T 32TDispersion Contours 32T......................................................................................................... 54

32T8.132T 32T1350 MT Horton Sphere - 1 32T ...................................................................................... 54

List of Tables

32TUTable 1U32T 32TU Typical Pasquill Stability classes U32T ......................................................................... 19

32TUTable 3U32T 32TU Ignition Probabilities as used in PHAST.U32T ............................................................. 23

32TUTable 4U32T 32TU Leak sizes considered U32T ........................................................................................... 24

32TUTable 5U32T 32TU Thermal Radiation Impact Criteria for Personnel U32T ................................................ 25

32TUTable 6U32T 32TU Thermal Radiation Impact Criteria for Equipment U32T ............................................... 25

32TUTable 7U32T 32TU Flammable (LFL) dispersion distances U32T ................................................................ 26

32TUTable 8U32T 32TU Jet fire radiation distances U32T .................................................................................... 34

32TUTable 9U32T 32TUPool fire radiation distances U32T .................................................................................. 41

32TUTable 5-7Fireball Radiation Distances U32T..................................................................................... 42

32TUTable 11U32T 32TUEstimated failure frequencyU32T ................................................................................... 46

List of Figures

32TUFigure 1 U32T 32TU Risk Acceptance CriteriaU32T ...................................................................................... 13

32TUFigure 2 U32T 32TU Event tree for Continuous release with rainout (from PHAST software)U32T ............ 21

32TUFigure 3 U32T 32TU Risk Contour for LPG Bottling Plant, RaipurU32T ...................................................... 48

32TUFigure 4 U32T 32TU FN Curve for LPG Bottling Plant, RaipurU32T ............................................................ 49




| Contents | of 54

DEFINITIONS

1. Hazard- A substance or circumstance which may cause injury or damage due to

being explosive, flammable, poisonous, corrosive, oxidizing, or otherwise harmful

2. Failure - A system or component failure occurs when the delivered service deviates

from the intended service. The cause of a failure is a fault, which resides, temporarily

or permanently in the system or component.

3. Dispersion – The mixing and spreading of gases in air, causing clouds to grow is

known as dispersion.

4. Vapour cloud explosions - Vapour cloud explosions are only possible under

confined and congested area. TNO Multi-energy model has been adopted for

determining the explosion overpressures.

5. Pool fire - Pool fires are themselves considered as an escalated scenario. In the AGRP

facility, pool fires could only occur if the liquid leak remains unseen and gets in

contact with an ignition source. Such a condition will require a reasonable amount of

time to develop.

6. Jet Fire - Jet fires could occur from release of gas which is immediately ignited, or

which burns back from a flash fire after delayed ignition.

7. Boiling Liquid Expanding Vapour Explosion - BLEVE is defined as any sudden

loss of containment of a fluid above its normal boiling point at the moment of vessel

failure. A common cause of this type of event is fire engulfment of a vessel which

contains pressurized liquid, where the heating both raises the pressure in the vessels

and lowers the yield strength of the material. The BLEVE event can give rise to a

blast wave, to fragment projection and if a flammable fluid is involved, to either a

fireball, a flash fire or a vapour cloud explosion.

8. Design Pressure – It is the pressure for which the installation is designed; the

installation should be able to withstand this pressure.

9. Explosion - A sudden release of energy that causes a blast is an explosion.

10. Exposure - Concentration or intensity that reaches the target person, usually

expressed in terms of concentration or intensity and duration

11. Flashing - Part of a superheated liquid that evaporates rapidly due to a relatively rapid

depressurisation, until the resulting vapour/liquid mixture has cooled to below boiling




| Contents | of 54

point at the end pressure. Superheat is the extra heat of a liquid made available by

decreasing the liquid’s temperature, for instance, by vaporisation, until the vapour

pressure equals that of the surroundings.

12. FN-curve - Log-log graph, where the x-axis represents the number of deaths, N, and

the y axis represents the cumulative frequency of the accidents, with the number of

deaths equal to N or more.

13. Frequency - The number of times an outcome is expected to occur in a given period

of time

14. Ignition source - A thing which is able to ignite a flammable cloud

15. Individual risk - the probability that in one year a person will become a victim of an

accident if the person remains permanently and unprotected in a certain location.

16. Loss of Containment event – An event resulting in the release of material to the

atmosphere.

17. Pasquill class - classification to qualify the stability of the atmosphere, indicated by a

letter ranging from A, for very unstable, to F, for stable.

18. Quantitative Risk Assessment - The process of hazard identification followed by a

numerical evaluation of effects of incidents, and consequences and probabilities, and

their combination into overall measures of risk.

19. Release - The discharge of a chemical from its containment, i.e. the process s and

storage equipment in which it is kept.

20. Risk contour - Line on a map connecting points having equal risk

21. Societal risk - The frequency (per year) that a group of at least a certain size will at

one time become victims of an accident.

22. Stability - Atmospheric stability; the extent to which vertical temperature gradients

promote or suppress turbulence in the atmosphere.




| INTRODUCTION| of 54

1 INTRODUCTION

IOCL owns total plot area Bottling Plant of 26.93 acres. The existing storage capacity of the

Bottling Plant at Raipur is 1750 MT. There will be no chemical process involved and the

operation carried out will be receipt of LPG in Bulk form in road tankers (or Pipe line in

future), storing the same in mounded bullets and filling of LPG into cylinders

(domestic/commercial/industrial) using electronic carousel and associated on-line conveyor

systems. The cylinders filled will be checked for quality and quantity and then dispatched by

packed cylinder truck.

The storage of LPG will be in liquid form in mounded bullet storage. The additional

mounded storage will be in 2 bullets each with a total capacity of 600 MT. The system of

mounded storage has been recognized as one of the safest form of storage for LPG. Bullets

will be submerged in ground and enacsed in four sided retaining wall having a designed layer

of earth over the bullets.

1.1 Project Objective

Objective of the QRA study of Terminal is to –

1. Identify hazards associated with normal operation and handling of hydrocarbon at

LPG Bottling Plant, Raipur.

2. Estimate the risks associated with the project facilities.

3. Benchmark the risk against PNGRB risk acceptance criteria and demonstrate that the

risk is within ALARP or broadly acceptable region.

4. Prepare ERDMP as per PNGRB regulations based on risk assessment.




| METHODOLOGY| of 54

2 METHODOLOGY

2.1 Methodology

Methodology adopted for risk assessment of LPG Bottling Plant, Raipur is as per following

principle steps;

1. Hazard Identification – Identify types of hazards which have the potential to cause

harm to the fatalities such as hydrocarbon releases.

2. Development of accident events – For the purposes of modeling, each hazard

identified is further divided into scenarios or events e.g. Leaks, ruptures etc.;

3. Frequency Analysis – The frequency of occurrence (i.e. likelihood of occurrence

within a given period) of each accidental event occurring is estimated from historical

data such as OGP Risk Assessment Data Directory, Process Release Frequencies,

Report no. 434-1 and 434-3, March 2010.

4. Consequence Modeling – The consequences (i.e. extent) arising from realization of

these accidental events such as Jet Fires, Explosions are calculated based on various

models;

5. Risk Analysis – Based on the fatalities arising from the consequences and the

frequency determined for an accidental event, the risk from the hazard is determined

in terms of individual risk;

6. Risk Summation – Risks associated with these accidental events are integrated to

quantify the risk levels at the facility;

7. Benchmarking – The risks are benchmarked against Risk Acceptance Criteria to

arrive at the list of events associated with “unacceptable” and “acceptable” risks;

8. Risk Ranking – The dominant risk contributors in terms of their risk level from

various accidental events are summarized.

2.2 QRA Approach

2.2.1 Result Interpretation The techniques used for risk prediction within the QRA have inherent uncertainties

associated with them due to the necessary simplifications required. In addition, QRA

incorporates a certain amount of subjective engineering judgment and the results are

subjected to levels of uncertainty. For this reason, the results should not be used as the sole





basis for decision making and should not drive deviations from sound engineering practice.

The results should be used as a tool to aid engineering judgment and, if used in this way, can

provide valuable information during the decision making process.

The QRA results are dependent on the assumptions made in the calculations, which are

clearly documented throughout the following sections of this report. Conservative

assumptions have been used, which helps to remove the requirement for detailed analysis of

the uncertainty. The results show the significant contributions to the overall risk and indicate

where worthwhile gains may be achieved if further enhancement of safety is deemed

necessary.

2.2.2 Risk Criteria PNGRB risk tolerability criterion in terms of Individual Risk (IR) is defined in the Section 61

of the Petroleum and Natural Gas Regulatory Board Act, 2006 (19 of 2006),Guidelines for

preparation of ERDMP, which is also applicable to IOCL facilities.

The maximum tolerable IR is 1.0 x 10-3 per year, whilst an IR of 1.0 x 10-6 per year is

regarded as broadly acceptable. An IR falling between these values is within the ALARP

region of risk acceptability and must be demonstrated to be as low as reasonably practicable.

These criteria are given here below –





Figure 1 Risk Acceptance Criteria

The assessment and control of risk are essential requirements for a proactive HSE

management system. In order to make a valued judgment and to decide on what risks are

acceptable, an easily understood set of criteria should be set and followed rigorously. Risk

criteria are required to promote consistency in evaluating the results of relevant studies and to

formulate a proactive approach to incident prevention. The following sections sets out the

basis for selecting the risk acceptance criteria and explains some of the techniques used to

arrive at the quantitative assessments made to understand the risk levels.

2.3 Risk

Risk is defined as the probability that within a fixed time period, usually one year, an

unwanted effect occurs. Consequently, risk is a dimensionless number. However, risk is often

expressed in units of frequency, ‘per year’. Since failure frequencies are low, the probability

that an unwanted effect will occur within a fixed time period of one year is, practically

speaking, equal to the frequency of occurrence per year.

Risk is the unwanted consequences of an activity connected with the probability of

occurrence.

2.4 Individual Risk Criteria (IR)

The tolerable risk level lies between the acceptable and unacceptable levels in which ALARP

must be demonstrated. Once a specific hazard is demonstrated by analysis to result in

acceptable risk there is no requirement, other than following normal precautions and SOPs

defined by company and statutes.

Workers would include IOCL employees and contractors. The public includes the general

public, visitors and any third party who is not directly involved in the IOCL work activities.

The tolerability criteria above should not be misinterpreted as the number of fatalities that

IOCL is prepared to accept in conducting operations. They must be used only in QRA context

as a statistical probability that equipment, systems and procedures fail and result in fatalities.





2.5 Presentation of Risk Results

2.5.1 Location Specific Individual Risk (LSIR) LSIR measures and expresses the risk exposure of personnel who are continuously present in

a particular area for the entire year (24x7x365). The risk exposure is calculated for all

relevant hazards and summed to give the overall risk of LPG Bottling Plant, Raipur.

In the fatality estimation, the consequences of each outcome due to a loss of containment are

represented by the probability of death for personnel continuously present in a particular area

of the plant when the event occurs. The LSIR can therefore be represented as:

LSIR = Σ (End event outcome frequency x Probability of fatality in area)

2.5.2 Individual Risk per Annum (IRPA) IRPA takes into account the amount of time personnel spend at the plant and is defined as the

probability of an individual being killed by the accident scenario per unit time. IRPA from

process events is determined as follows:

IRPA = Σ (LSIR x Probability of personnel in area) x Presence factor

The presence factor is the actual time spent at the plant in a year.

2.5.3 Potential Loss of Life (PLL) The PLL is a measure of risk to a group of personnel as a whole and is an average rate of

fatalities at the plant. The PLL can be established using the following equation –

PLL = Σ (IRPA) x Number of personnel in worker group




| HAZARD IDENTIFICATION| of 54

3 HAZARD IDENTIFICATION

A substance or circumstance which may cause injury or damage due to being explosive,

flammable, poisonous, corrosive, oxidizing, or otherwise harmful is defined as hazard.

3.1 Hazards associated with storage tanks

As per UK HSE’s guideline HSG176, the main hazards associated with the storage and

handling of flammable liquids are fire and explosion, involving either the liquid or the vapour

given off from it. Fires and explosions are likely to occur when vapour or liquid is released

accidentally or deliberately into areas where there may be an ignition source, or when an

ignition source is introduced into an area where there may be flammable atmospheres.

Common causes of such incidents include,

1. Inadequate design and installation of equipment;

2. Inadequate inspection and maintenance;

3. Failure or malfunction of equipment;

4. Lack of awareness of the properties of flammable liquids;

5. Operator error, due to lack of training;

6. Exposure to heat from a nearby fire;

7. Inadequate control of ignition sources;

8. Electrostatic discharges;

9. Heating materials above their auto-ignition temperature;

10. Dismantling or disposing of equipment containing flammable liquids;

Hot work on or close to flammable liquid vessels

3.2 Hazard Categories

In order to identify hazards posed by the facility, it is very important to identify the type of

hazards posed by the materials being handled. IOCL handles and stores LPG.

All these are flammable and pose fire and burn risk. As there is no toxic material being

handled at MOT, there is no toxic risk envisaged

3.3 Hazardous Properties

Combustion of liquids occurs when flammable vapours released from the surface of the

liquid ignite. The amount of flammable vapour given off from a liquid, and therefore the





extent of the fire or explosion hazard, depends largely on the temperature of the liquid, how

much of the surface area is exposed, how long it is exposed for, and the air movement over

the surface. The hazard also depends on the physical properties of the liquid such as

flashpoint, auto-ignition temperature, viscosity, and the upper and lower explosion limits.

These are the various materials are stored in tanks & have been taken into Quantitative Risk

Assessment.

Properties LPG HSD

Flash Point(°C) < -60 > 35°C

LFL 1.8 % (V) 0.4 %

UFL 8.5 % (V) 5 %

Volatility

Vapour Pressure 2.007 at 21.1

°C (70.0 °F) 0.5 mm of Hg

Boiling point (°C)

-0.5 (31.1 °F)

at 1,013.25

hPa

110 °C to375°C

Relative density of gas

or vapour to air 2 to 3 3 to 5

Physical State Gas Liquid

Auto Ignition temp(°C) 287°C 230°Cto250°C

3.4 Scenarios

Considering hazardous properties and facility, following scenarios have been considered for

consequence and risk assessment –

As per OGP – Risk Assessment Directory, for each of scenario four leak sizes are considered

for release from Piping,





1. Small leak – Leak size 5 mm (representative size of 1 to 10mm)

2. Medium Leak – Leak size 25 mm (representative size of 10mm to 50mm)

3. Large Leak – Leak size 100 mm (representative size of 50 to 150mm)

4. Full Bore Rupture (FBR)

In case of release from storage, following leak sizes are considered:

1. Small leak – Leak size 5 mm (representative size of 1 to 10mm)

2. Medium Leak – Leak size 25 mm (representative size of 10mm to 50mm)

3. Large Leak – Leak size 100 mm (representative size of 50 to 150mm)

4. Catastrophic Rupture

3.4.1 List of identified Scenarios

SN Section Number Section Description

1 IS-01 Piping from LPG Bullets to suction of compressors 2 IS-02 Piping from discharge of compressors to vapour arm

3 IS-03 Piping from liquid Loading & unloading arm to inlet of LPG Bullets

4 IS-04 Piping from outlet of LPG Bullets to suction of LPG filling pumps

5 IS-05 Piping from discharge of LPG filling pumps to filling hall (LPG Cylinder filling operation)

6 IS-06 Piping from LPG Bullets to suction of LPG tanker loading pump

7 IS-07 Piping from discharge of LPG tanker loading pump to LPG tanker loading arm

8 IS-08 100 MT Horton Sphere - 1 9 IS-09 100 MT Horton Sphere - 2

10 IS-10 100 MT Horton Sphere - 3 11 IS-11 100 MT Horton Sphere - 4 12 IS-12 100 MT Horton Sphere - 5 13 IS-13 450 MT Horton Sphere - 6 14 IS-14 450 MT Horton Sphere - 7 15 IS-15 450 MT Horton Sphere - 8 20 IS-16 600 MT Mounded Bullet - 9 21 IS-17 600 MT Mounded Bullet - 10





SN Section Number Section Description

25 IS18 Diesel Tank 26 IS-19 Diesel Tank Transfer pump

3.5 Climatic Conditions

3.5.1 Meteorological Data The consequences of released flammable material are largely dependent on the prevailing

weather conditions. For the assessment of major scenarios involving release of flammable

material, 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.

3.5.2 Atmospheric Stability Classes The tendency of the atmosphere to resist or enhance vertical motion and thus turbulence is

termed as stability. Stability is related to both the change of temperature with height (the

lapse rate) driven by the boundary layer energy budget, and wind speed together with surface

characteristics (roughness)

A neutral atmosphere neither enhances nor inhibits mechanical turbulence. An unstable

atmosphere enhances turbulence, whereas a stable atmosphere inhibits mechanical

turbulence.

Stability classes are defined for different meteorological situations, characterised by wind

speed and solar radiation (during the day) and cloud cover during the night. The so called

Pasquill-Turner stability classes dispersion estimates include six (6) stability classes as

below:

A – Very Unstable B – Unstable C – Slightly Unstable

D – Neutral E – Stable F – Very Stable





The typical stability classes for various wind speed and radiation levels during entire day are

presented in table below:

Table 1 Typical Pasquill Stability classes

Wind Speed (m/s)

Day : Solar Radiation Night : cloud Cover

Strong Moderate Slight Think < 40% Moderate Overcast >

80%

<2 A A-B B - - D

2-3 A-B B C E F D

3-5 B B-C C D E D

5-6 C C-D D D D D

>6 C D D D D D

The wind speed and Pasquill Stability class data used for the study is summarized below:

Wind Speed Stability class

2m/s F

5 m/s D




| EVENTS AND IGNITION PROBABILITY| of 54

4 EVENTS AND IGNITION PROBABILITY

4.1 Event Tree

PHAST has an in-built event tree for determining the outcomes which are based on two types

of releases namely continuous and instantaneous. Leaks are considered to be continuous

releases whereas, ruptures are considered to be instantaneous releases.

The event tree takes in to account factors affecting consequence of a release such as;

1. Material properties such as

a. Flammability / toxicity

b. Flash point

c. Phase of material

d. Density of material

2. Ambient conditions

3. Availability of Immediate / Delayed ignition

Based on these the event trees used in PHAST Risk are given here below –





Figure 2 Event tree for Continuous release with rainout (from PHAST software)

4.2 Consequential Events

4.2.1 Jet Fire A jet fire occurs following the ignition and combustion of pressurized flammable fluid

continuously released from a pipe or orifice, which burns close to its release plane. The high

heat intensity poses a hazard to personnel and causes damage to unprotected equipment due

to direct flame impingement, causing it to fail within several minutes. Jet flames dissipate

thermal radiation, away from the flame’s visible boundaries and transmit heat energy that

could be hazardous to life and property.





4.2.2 Pool Fire The released flammable material which is a liquid stored below its normal boiling point, will

collect in a pool. The geometry of the pool will be dictated by the surroundings. If the liquid

is stored under pressure above its normal boiling point, then a fraction of the liquid will flash

into vapour and the remaining portion will form a pool in the vicinity of the release point.

Once sustained combustion is achieved, liquid fires quickly reach steady state burning. The

heat release rate is a function of the liquid surface area exposed to air. An unconfined spill

will tend to have thin fuel depth (typically less than 5 mm) which will result in slower

burning rates. A confined spill is limited by the boundaries (e.g. a dyke area) and the depth

of the resulting pool is greater than that for an unconfined spill. Pool fires are less directional

and so may affect a larger area although it is mostly influenced by wind conditions. They will

also cause structural failure of equipment although the time taken is longer than jet fires.

4.2.3 Flammable Gas Dispersion / Flash Fire Flash Fire occurs when a vapour cloud of flammable material burns. The cloud is typically

ignited on the edge and burns towards the release point. The duration of flash fire is very

short (seconds), but it may continue as Jet fire if the release continues. The overpressures

generated by the combustion are not considered significant in terms of damage potential to

persons, equipment or structures. The major hazard from flash fire is direct flame

impingement. Typically, the burn zone is defined as the area the vapour cloud covers out to

the LFL. Even where the concentration may be above the UFL, turbulent induced

combustion mixes the material with air and results in flash fire.

4.3 Ignition Probability

There are 2 main types of ignitions, namely:

1. Immediate ignition — Ignition following rapidly after the release is initiated, prior to

personnel being able to escape from the area; and

2. Delayed ignition — Gas cloud drifting over an ignition source and depending on the

ignition delay, personnel may be able to escape before fire or explosion occurs.

PHAST has systematic approach for deciding ignition probabilities depending upon type of

release, phase of material released, reactivity and release rate. These have been used for the

purpose of the study.





Table 2 Ignition Probabilities as used in PHAST.

Type and Size of Release Type of Material Released

Continuous Instantaneous

K0 K1 K2 K3 K4 Gas; liquid: TRflR< 0P

oPC liquid: liquid: liquid: liquid

Reactivity: Reactivity: TRflR< 21 P

oPC

TRflR< 55P

oPC

TRflR< 100 P

oPC

TRflR> 100P

oPC High, Average,

Unknown Low

< 10 kg/s < 1000 kg 0.2 0.02 0.065 0.01 0 0

10 - 100 kg/s 1000 - 10,000 kg 0.5 0.04 0.065 0.01 0 0

> 100 kg/s > 10,000 kg 0.7 0.09 0.065 0.01 0 0




| CONSEQUENCE ANALYSIS| of 54

5 CONSEQUENCE ANALYSIS

Consequence analysis is carried out to determine the extent of spread (dispersion) by

accidental release which may lead to jet fire or explosion resulting into generating heat

radiation, overpressures, explosion impact etc.

5.1 Modes of failure

Leak and tank on fire are two types of scenarios considered in the study. Tank on fire is

applicable only to floating roof tank. For leak scenario, the leak sizes considered are as under,

Table 3 Leak sizes considered

Leak Sizes

Leak Description

Representative Hole Diameter Remarks

Small (0 – 10 mm)

5 mm Represents leaks from flange joints and pump seals.

Medium (10 – 50 mm)

25 mm Represents release due to failure of small bore piping (instrument tapping, drain connection etc.).

Large (50 – 150 mm)

100 mm Represents release due to failure of large section of equipment or piping (e.g. damage due to external impact, failure of flexible pipe/ hose).

Rupture >150mm Represents release due to failure of large section of equipment or piping equivalent to its rupture / full bore release.

Above leak sizes are taken from Centre of Chemical Process Safety(CCPS) AIChE

CCPS QRA guidelines, chapter 2 – Consequence analysis, also mentions about leak duration.

It says that the Department of Transportation (1980) LNG Federal Safety Standards specified

10-min leak duration; other studies (Rijnmond Public Authority, 1982) have used 3 min if

there is a leak detection system combined with remotely actuated isolation valves. Other

analysts use a shorter duration. Actual release duration may depend on the detection and

reaction time for automatic isolation devices and response time of the operators for manual

isolation. The rate of valve closure in longer pipes can influence the response time. Due to the

water hammer effect, designers may limit the rate of closure in liquid pipelines.

Considering this and isolated facility of IOCL, we have considered 10min discharge duration

as a conservative approach.





5.2 Impact Criteria

An impact criterion relates the modeling of the hazard effects to the resultant consequences to

personnel and asset, and determines the nature and detail of results required from the

simulation.

The impact criteria for personnel and equipment on IOCL are summarised in the following

sub-sections.

5.2.1 Personnel Following table defines the impact of thermal radiation on personnel. The thermal radiation

levels listed includes solar radiation of 1 kW/m2.

Table 4 Thermal Radiation Impact Criteria for Personnel

Thermal Radiation Effect Description

1.6 kW/m2 Maximum radiant heat intensity at any location where personnel with appropriate clothing can be continuously exposed.

4 kW/m2 Maximum radiant heat intensity in areas where emergency actions lasting 2 to 3 minutes can be required by personnel without shielding but with appropriate clothing.

12.5 kW/m2 Maximum radiant heat intensity in areas where emergency actions lasting up to 30 seconds can be required by personnel without shielding but with appropriate clothing.

37.5 kW/m2 Limiting thermal radiation intensity for escape actions lasting a few seconds. Significant chance of fatality for extended exposure.

Table 5 Thermal Radiation Impact Criteria for Equipment

Thermal Radiation Effect Description

4 kW/m2 Glass breakage (30 minute exposure)

12.5 to 15 kW/m2 Piloted ignition of wood, melting of plastic (>30 minute exposure)

18 to 20 kW/m2 Cable insulation degrades (>30 minute exposure)

10 or 20 kW/m2 Ignition of fuel oil (120 or 40 seconds, respectively)

25 to 32 kW/m2 Unpiloted ignition of wood, steel deformation (>30 minute exposure)

35 to 37.5 kW/m2 Process equipment and structural damage (including storage tanks) (>30 minute exposure)

100 kW/m2 Steel structure collapse (>30 minute exposure)





The damage effects are different for different scenarios considered. In order to appreciate the

damage effects produced by various scenarios, it will be appropriate to discuss the

physiological/ physical effects of the accidental loss of containment event.

5.3 Initial Release Rates

A release at the tank farm may be modeled using a representative hole size or by fixing the

release rate for a given scenario. In this assessment, the former method was used as the hole

size is a major factor in influencing the characteristics of a release and determines the initial

hydrocarbon mass release rate as well as release duration.

Based on the hole sizes, material properties and operating / storage conditions, the

corresponding initial release rates for fire modeling are obtained from PHAST.

Liquid flash rates were used for dispersion in case of releases as there is no gaseous material

being handled. 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.

5.4 Flammable Gas Dispersion

The significance of these distances is that the cloud will ignite if it were to get source of

ignition within UFL and LFL zone. Following table gives the LFL and UFL dispersion

distances for various leak sizes under different weather conditions.

The resultant flammable dispersion distances are given in the table below,

Table 6 Flammable (LFL) dispersion distances

SN Scenario ID Description of scenario

Leak Size in mm

Flammable distances in m Conc. 2F 5D

1 IS01 Piping from LPG Bullets to suction of compressors

5 UFL 0.31 0.32 LFL 1.57 1.47

0.5 LFL 2.89 2.45

25 UFL 1.53 1.54 LFL 7.56 6.51

0.5 LFL 15.72 11.49

100 UFL 6.08 5.97 LFL 40.45 39.65

0.5 LFL 88.24 97.75






Leak Size in mm


FBR UFL 9.24 9.02 LFL 66.71 70.66

0.5 LFL 110.12 129.97

2 IS02

Piping from discharge of

compressors to vapour arm

5 UFL 0.35 0.36 LFL 1.75 1.63

0.5 LFL 3.22 2.73

25 UFL 1.70 1.71 LFL 8.45 7.28

0.5 LFL 18.32 14.03

100 UFL 6.72 6.64 LFL 46.59 46.14

0.5 LFL 88.08 102.09

FBR UFL 6.84 6.73 LFL 47.89 47.08

0.5 LFL 88.76 103.60

3 IS03

Piping from liquid Loading & unloading arm to

inlet of LPG Bullets

5 UFL 1.61 1.58 LFL 6.82 5.47

0.5 LFL 13.52 8.16

25 UFL 7.87 7.38 LFL 54.02 49.84

0.5 LFL 123.87 105.88

100 UFL 39.39 38.90 LFL 250.27 303.56

0.5 LFL 369.63 428.38

FBR UFL 66.09 65.56 LFL 299.69 371.04 0.5 LFL 417.64 490.24

4 IS04

Piping from outlet of tanks to suction of LPG filling pumps

5 UFL 0.32 0.32 LFL 1.60 1.49

0.5 LFL 2.94 2.49

25 UFL 1.55 1.56 LFL 7.67 6.61

0.5 LFL 16.09 11.81

100 UFL 6.18 6.08 LFL 41.26 40.49






Leak Size in mm


0.5 LFL 99.04 105.45

FBR UFL 16.59 16.46 LFL 118.08 131.98

0.5 LFL 179.17 211.45

5 IS05

Piping from discharge of LPG filling to filling

hall (LPG Cylinder filling

operation)

5 UFL 2.01 1.97 LFL 8.55 6.72

0.5 LFL 19.14 11.91

25 UFL 9.91 9.17 LFL 70.57 69.25

0.5 LFL 153.74 141.49

100 UFL 51.66 51.02 LFL 257.24 316.50

0.5 LFL 360.07 424.44

FBR UFL 85.42 84.56 LFL 303.07 383.64

0.5 LFL 404.71 479.29

6 IS06

Piping from LPG Bullets to suction

of LPG tanker loading pump

5 UFL 0.33 0.34 LFL 1.68 1.56

0.5 LFL 3.07 2.60

25 UFL 1.63 1.64 LFL 8.04 6.91

0.5 LFL 17.18 12.80

100 UFL 6.48 6.37 LFL 44.01 43.31

0.5 LFL 97.60 112.02

FBR UFL 9.85 9.61 LFL 73.24 76.62

0.5 LFL 121.03 142.44

7 IS07

Piping from discharge of LPG

tanker loading pump tanker loading arm

5 UFL 1.83 1.78 LFL 7.37 5.72

0.5 LFL 15.92 8.68

25 UFL 8.94 8.15 LFL 63.92 58.65

0.5 LFL 164.00 108.60 100 UFL 47.09 46.37






Leak Size in mm

Flammable distances in m Conc. 2F 5D LFL 264.13 312.74

0.5 LFL 571.25 461.15

FBR UFL 123.66 180.36 LFL 706.25 1133.53

0.5 LFL 1643.72 1817.43

8 IS08

Loss of containment of LPG from 100

MT Horton Sphere 1

5

UFL 0.18 0.14

LFL 1.89 1.23

LFL Frac 2.76 2.44

25

UFL 0.90 0.68

LFL 8.82 5.86

LFL Frac 12.65 10.24

100

UFL 3.55 2.71

LFL 30.23 21.72

LFL Frac 54.41 35.71

FBR

UFL 18.29 20.92

LFL 49.89 79.11

LFL Frac 96.86 160.45

9 IS09


MT Horton Sphere 2

5

UFL 0.18 0.14

LFL 1.89 1.23

LFL Frac 2.76 2.44

25

UFL 0.90 0.68

LFL 8.82 5.86

LFL Frac 12.65 10.24

100

UFL 3.55 2.71

LFL 30.23 21.72

LFL Frac 54.41 35.71

FBR UFL 18.29 20.92

LFL 49.89 79.11






Leak Size in mm


LFL Frac 96.86 160.45

10 IS10


MT Horton Sphere 3

5

UFL 0.18 0.14

LFL 1.89 1.23

LFL Frac 2.76 2.44

25

UFL 0.90 0.68

LFL 8.82 5.86

LFL Frac 12.65 10.24

100

UFL 3.55 2.71

LFL 30.23 21.72

LFL Frac 54.41 35.71

FBR

UFL 18.29 20.92

LFL 49.89 79.11

LFL Frac 96.86 160.45

11 IS11


MT Horton Sphere 4

5

UFL 0.18 0.14

LFL 1.89 1.23

LFL Frac 2.76 2.44

25

UFL 0.90 0.68

LFL 8.82 5.86

LFL Frac 12.65 10.24

100

UFL 3.55 2.71

LFL 30.23 21.72

LFL Frac 54.41 35.71

FBR

UFL 18.29 20.92

LFL 49.89 79.11

LFL Frac 96.86 160.45

12 IS12 Loss of containment of 5

UFL 0.18 0.14

LFL 1.89 1.23






Leak Size in mm


LPG from 100 MT Horton

Sphere 5 LFL Frac 2.76 2.44

25

UFL 0.90 0.68

LFL 8.82 5.86

LFL Frac 12.65 10.24

100

UFL 3.55 2.71

LFL 30.23 21.72

LFL Frac 54.41 35.71

FBR

UFL 18.29 20.92

LFL 49.89 79.11

LFL Frac 96.86 160.45

13 IS13


MT Horton Sphere 6

5

UFL 0.62 0.47

LFL 6.45 4.20

LFL Frac 9.41 8.33

25

UFL 3.08 2.31

LFL 30.06 19.98

LFL Frac 43.12 34.90

100

UFL 12.10 9.24

LFL 103.04 74.05

LFL Frac 185.48 121.73

FBR

UFL 62.35 71.31

LFL 170.09 269.69

LFL Frac 330.19 546.98

14 IS14


MT Horton Sphere 7

5

UFL 0.62 0.47

LFL 6.45 4.20

LFL Frac 9.41 8.33

25 UFL 3.08 2.31

LFL 30.06 19.98






Leak Size in mm


LFL Frac 43.12 34.90

100

UFL 12.10 9.24

LFL 103.04 74.05

LFL Frac 185.48 121.73

FBR

UFL 62.35 71.31

LFL 170.09 269.69

LFL Frac 330.19 546.98

15 IS15


MT Horton Sphere 8

5

UFL 0.62 0.47

LFL 6.45 4.20

LFL Frac 9.41 8.33

25

UFL 3.08 2.31

LFL 30.06 19.98

LFL Frac 43.12 34.90

100

UFL 12.10 9.24

LFL 103.04 74.05

LFL Frac 185.48 121.73

FBR

UFL 62.35 71.31

LFL 170.09 269.69

LFL Frac 330.19 546.98

16 IS16

Loss of containment of

LPG from 600MT Mounded

Bullets 9

5

UFL 0.83 0.62

LFL 8.60 5.60

LFL Frac 12.55 11.10

25

UFL 4.11 3.08

LFL 40.08 26.64

LFL Frac 57.49 46.53

100 UFL 16.13 12.32

LFL 137.39 98.73






Leak Size in mm


LFL Frac 247.30 162.31

FBR

UFL 83.13 95.08

LFL 226.78 359.59

LFL Frac 440.25 729.30

17 IS17


LPG from 600MT Mounded

Bullets 10

5

UFL 0.83 0.62

LFL 8.60 5.60

LFL Frac 12.55 11.10

25

UFL 4.11 3.08

LFL 40.08 26.64

LFL Frac 57.49 46.53

100

UFL 16.13 12.32

LFL 137.39 98.73

LFL Frac 247.30 162.31

FBR

UFL 83.13 95.08

LFL 226.78 359.59

LFL Frac 440.25 729.30

18 IS18


Diesel form Diesel Tank

5 UFL 2.16 1.89 LFL 3.43 3.98

0.5 LFL 3.46 3.98

25 UFL 6.18 6.02 LFL 6.34 6.38

0.5 LFL 6.35 6.40

100 UFL 8.70 8.72 LFL 8.80 8.83

0.5 LFL 8.80 8.84

FBR UFL 16.02 18.00 LFL 16.18 18.15

0.5 LFL 16.21 18.18 19 IS19 Loss of 5 UFL 7.12 6.96






Leak Size in mm


containment of Diesel from Diesel Tank

Transfer pump

LFL 7.47 7.57 0.5 LFL 7.50 7.61

25 UFL 9.22 9.29 LFL 9.27 9.38

0.5 LFL 9.28 9.39

FBR UFL 11.16 11.25 LFL 11.24 11.35

0.5 LFL 11.24 11.36 Notes:

NR: Not Reached

FBR: Full Bore Rupture

It can be noted that the flammable cloud dispersion distances (LFL) are more in case of full

bore rupture of LPG Mounded Bullets. It goes up to approximately 729m for 5D wind

condition.

5.5 Radiation Distances due to Jet Fire

A jet or spray fire is a turbulent diffusion flame resulting from the combustion of a fuel

continuously released with some significant momentum in a particular direction or directions.

The properties of jet fires depend on the fuel composition, release conditions, release rate,

release geometry, direction and ambient wind conditions.

Radiation due to jet fire are given in the table below –

Table 7 Jet fire radiation distances


Leak Size in

mm

Jet Fire distances in m Radiation

kw/m2 2F 5D

1 IS01 Piping from LPG Bullets to suction of compressors

5 4 NR NR

12.5 NR NR 37.5 NR NR

25 4 14.92 15.51

12.5 11.36 12.42 37.5 NR NR






Leak Size in

mm


kw/m2 2F 5D

100 4 61.58 61.73

12.5 46.30 49.68 37.5 35.47 40.20

FBR 4 90.79 89.24

12.5 66.47 70.32 37.5 50.05 55.65

2 IS02 Piping from discharge of compressors to vapour

arm

5 4 NR NR

12.5 NR NR 37.5 NR NR

25 4 17.04 17.61

12.5 13.30 14.42 37.5 NR NR

100 4 69.67 69.54

12.5 52.30 55.67 37.5 40.04 44.81

FBR 4 70.71 70.53

12.5 53.02 56.41 37.5 40.57 45.37

3 IS03 Piping from liquid

Loading & unloading arm to inlet of LPG Bullets

5 4 15.73 13.60

12.5 12.57 10.36 37.5 10.57 8.33

25 4 68.66 59.68

12.5 54.60 45.43 37.5 46.19 36.97

100 4 239.28 207.78

12.5 188.06 156.95 37.5 157.64 126.76

FBR 4 348.64 293.67

12.5 273.13 222.73 37.5 228.28 180.40

4 IS04 Piping from outlet of tanks to suction of LPG filling

pumps

5 4 NR NR

12.5 NR NR 37.5 NR NR

25 4 15.19 15.79






Leak Size in

mm


kw/m2 2F 5D

12.5 11.58 12.66 37.5 NR NR

100 4 62.59 62.70

12.5 47.02 50.42 37.5 36.02 40.77

FBR 4 146.89 141.27

12.5 104.23 108.41 37.5 77.46 83.78

5 IS05

Piping from discharge of LPG filling to filling hall

(LPG Cylinder filling operation)

5 4 19.70 17.05

12.5 15.78 13.03 37.5 13.34 10.57

25 4 85.63 74.38

12.5 67.97 56.56 37.5 57.44 46.01

100 4 297.86 253.16

12.5 233.76 191.91 37.5 195.71 155.45

FBR 4 433.70 355.78

12.5 339.34 271.12 37.5 283.30 220.45

6 IS06 Piping from LPG Bullets to suction of LPG tanker

loading pump

5 4 NR NR

12.5 NR NR 37.5 NR NR

25 4 16.01 16.62

12.5 12.31 13.43 37.5 NR NR

100 4 65.55 65.53

12.5 49.14 52.57 37.5 37.58 42.41

FBR 4 96.52 94.63

12.5 70.45 74.32 37.5 52.97 58.64

7 IS07 Piping from discharge of LPG tanker loading pump 5

4 16.52 14.32 12.5 13.21 10.91






Leak Size in

mm


kw/m2 2F 5D

tanker loading arm 37.5 11.12 8.78

25 4 71.74 62.48

12.5 56.97 47.47 37.5 48.11 38.55

100 4 249.18 216.80

12.5 195.49 163.42 37.5 163.54 131.64

FBR 4 NR NR

12.5 NR NR 37.5 NR NR

8 IS08 Loss of containment of

LPG from 100 MT Horton Sphere 1

5 4 0.68 0.68

12.5 0.61 0.61

37.5 NR NR

25 4 3.59 3.72

12.5 2.97 3.22

37.5 2.48 2.82

100 4 14.62 14.58

12.5 11.04 11.77

37.5 8.50 9.56



5 4 0.68 0.68

12.5 0.61 0.61

37.5 NR NR

25 4 3.59 3.72

12.5 2.97 3.22

37.5 2.48 2.82

100 4 14.62 14.58

12.5 11.04 11.77

37.5 8.50 9.56



5 4 0.68 0.68

12.5 0.61 0.61

37.5 NR NR

25 4 3.59 3.72

12.5 2.97 3.22

37.5 2.48 2.82






Leak Size in

mm


kw/m2 2F 5D

100 4 14.62 14.58

12.5 11.04 11.77

37.5 8.50 9.56



5 4 0.68 0.68

12.5 0.61 0.61

37.5 NR NR

25 4 3.59 3.72

12.5 2.97 3.22

37.5 2.48 2.82

100 4 14.62 14.58

12.5 11.04 11.77

37.5 8.50 9.56



5 4 0.68 0.68

12.5 0.61 0.61

37.5 NR NR

25 4 3.59 3.72

12.5 2.97 3.22

37.5 2.48 2.82

100 4 14.62 14.58

12.5 11.04 11.77

37.5 8.50 9.56



5 4 2.30 2.30

12.5 2.06 2.06

37.5 NR NR

25 4 12.26 12.70

12.5 10.11 10.98

37.5 8.45 9.63

100 4 49.84 49.72

12.5 37.63 40.13

37.5 28.99 32.58



5 4 2.30 2.30

12.5 2.06 2.06

37.5 NR NR

25 4 12.26 12.70






Leak Size in

mm


kw/m2 2F 5D

12.5 10.11 10.98

37.5 8.45 9.63

100 4 49.84 49.72

12.5 37.63 40.13

37.5 28.99 32.58



5 4 2.30 2.30

12.5 2.06 2.06

37.5 NR NR

25 4 12.26 12.70

12.5 10.11 10.98

37.5 8.45 9.63

100 4 49.84 49.72

12.5 37.63 40.13

37.5 28.99 32.58


LPG from 600MT Mounded Bullets 9

5 4 3.07 3.07

12.5 2.75 2.75

37.5 NR NR

25 4 16.34 16.93

12.5 13.48 14.64

37.5 11.27 12.84

100 4 66.45 66.29

12.5 50.17 53.51

37.5 38.65 43.44


LPG from 600MT Mounded Bullets 10

5 4 3.07 3.07

12.5 2.75 2.75

37.5 NR NR

25 4 16.34 16.93

12.5 13.48 14.64

37.5 11.27 12.84

100 4 66.45 66.29

12.5 50.17 53.51

37.5 38.65 43.44

18 IS18 Loss of containment of Diesel from Diesel Tank 5

4 NR NR 12.5 NR NR






Leak Size in

mm


kw/m2 2F 5D

37.5 NR NR

25 4 2.43 2.34

12.5 NR 0.98 37.5 NR NR

100 4 NR NR

12.5 NR NR 37.5 NR NR


Diesel from Diesel Tank Transfer pump

5 4 1.31 0.76

12.5 NR NR 37.5 NR NR

25 4 1.37 1.84

12.5 NR NR 37.5 NR NR

100 4 3.30 3.18

12.5 1.96 1.98 37.5 NR NR

Notes:

NR: Not Reached


Jet fire is a credible scenario for gas facility, in the event of loss of containment from LPG

pump discharge, the jet fire radiation distances for 4kW/m2 radiation goes up to approx.

433m for 2F wind condition.

5.6 Radiation Distances due to Pool Fire

A pool fire involves a horizontal, upward-facing, combustible fuel. When spilled, the

Flammable/combustible liquid may form a pool of any shape and thickness, and may be

controlled by the confinement of the area geometry such as a dyke or curbing. Once ignited, a

pool fire spreads rapidly over the surface of the liquid spill area.

When a spilled liquid is ignited, a pool fire develops. Provided that an ample supply of

oxygen is available, the amount of surface area of the given liquid becomes the defining

parameter. The diameter of the pool fire depends upon the release mode, release quantity (or





rate), and burning rate. Liquid pool fires with a given amount of fuel can burn for long

periods of time if they have a small surface area or for short periods of time over a large spill

area.

Following table gives radiation distances for pool fire scenario where it is assumed that the

dyke will contain leaked material and would not allow it to flow beyond the restricted bund

area.

Table 8 Pool fire radiation distances


Leak Size in mm

Pool Fire distances in m

Radiation kw/m2 2F 5D

1 IS18 Diesel Tank

5

4 84.30 98.39

12.5 42.97 43.60

37.5 NR NR

25

4 97.31 112.92

12.5 51.34 52.14

37.5 NR NR

100

4 33.97 37.70

12.5 19.19 23.48

37.5 11.61 12.15

FBR

4 90.52 108.29

12.5 44.58 47.52

37.5 NR NR

2 IS19 Diesel Tank Transfer pump 5

4 42.15 49.195

12.5 21.485 21.8






Leak Size in mm

Pool Fire distances in m

Radiation kw/m2 2F 5D

37.5 NR NR

25

4 48.655 56.46

12.5 25.67 26.07

37.5 NR NR

100

4 16.985 18.85

12.5 9.595 11.74

37.5 5.805 6.075

FBR

4 45.26 54.145

12.5 22.29 23.76

37.5 NR NR

NR: Not Reached


The above results show that the pool fire radiation distances are in case of Diesel tank which

goes up to 108 m for 4kW/m2 radiation for 5D wind Condition.

Radiation Distances due to Fireball

Table 5-9Fireball Radiation Distances


Leak Size in

mm

Fireball distances in m Radiation

kw/m2 2F 5D

1 IS1 Piping from LPG Bullets to suction of compressors 100

4 44.98 42.51 12.5 20.49 18.89 37.5 NR NR

2 IS2 Piping from discharge of compressors to vapour arm 100

4 40.78 38.61 12.5 18.98 17.62






Leak Size in

mm


kw/m2 2F 5D

37.5 NR NR

FBR 4 40.78 38.61

12.5 18.98 17.62 37.5 NR NR

3 IS3 Piping from liquid Loading & unloading arm to inlet of

LPG Bullets FBR

4 269.17 247.76 12.5 136.72 124.05 37.5 16.20 NR

4 IS4 Piping from outlet of LPG Bullets to suction of LPG

filling pumps

100 4 74.03 69.54

12.5 34.90 32.09 37.5 NR NR

FBR 4 74.03 69.54

12.5 34.90 32.09 37.5 NR NR

5 IS5

Piping from discharge of LPG filling pumps to filling hall (LPG Cylinder filling

operation)

100 4 268.22 247.55

12.5 142.07 130.35 37.5 50.20 39.36

FBR 4 268.22 247.55

12.5 142.07 130.35 37.5 50.20 39.36

6 IS6 Piping from LPG Bullets to

suction of LPG tanker loading pump

100 4 52.18 49.24

12.5 24.29 22.44 37.5 NR NR

FBR 4 52.18 49.24

12.5 24.29 22.44 37.5 NR NR

7 IS7 Piping from discharge of

LPG tanker loading pump to LPG tanker loading arm

FBR 4 1484.53 1299.07

12.5 796.87 690.66 37.5 269.58 147.03

8 IS8 100 MT Horton Sphere 1 FBR 4 300.53 263.78

12.5 160.19 139.02 37.5 50.61 22.69


12.5 160.19 139.02 37.5 50.61 22.69






Leak Size in

mm


kw/m2 2F 5D


12.5 160.19 139.02 37.5 50.61 22.69


12.5 160.19 139.02 37.5 50.61 22.69


12.5 160.19 139.02 37.5 50.61 22.69


12.5 546.11 473.94 37.5 172.55 77.35


12.5 546.11 473.94 37.5 172.55 77.35


12.5 546.11 473.94 37.5 172.55 77.35

16 IS16 600MT Mounded Bullets FBR 4 1366.03 1199.02

12.5 728.14 631.92 37.5 230.06 103.13

17 IS17 600MT Mounded Bullets FBR 4 1366.03 1199.02

12.5 728.14 631.92 37.5 230.06 103.13

Notes:

NR: Not Reached


In case of Fireball for gas facility, in the event of loss of containment of LPG from 600MT

Mounded Bullets, the Fireball radiation distances for 4kW/m2 radiation goes up to approx.

1366 m for 5D wind condition.




| LIKELIHOOD ESTIMATION| of 54

6 LIKELIHOOD ESTIMATION

Frequency analysis was conducted for each of the release scenarios identified based on the

number of potential leak sources contained within each isolatable section. Leaks may occur

from various components such as tanks, pumps, pipes, valves and flanges. Each component

has a generic historical leak frequency per single item such as a leak frequency per flange-

year or per meter of pipe per year. Generic failure data for equipment and piping items is

derived from historical leak frequency data compiled by the International Association of Oil

& Gas Producers (OGP). For components other than Tanks, Report No. 434 – 1 – Process

Release Frequencies dtd March 2010 has been used and for storage tanks, Report No. 434 – 3

– Storage incident frequencies dtd March 2010 has been referred to.

6.1 Failure Frequencies

This scenario is considered only for floating roof type of tank. Under section 2 of Report No.

434 – 3 the failure frequency of sunken roof in case of floating roof tank is 1.1 × 10-3/avg

year.

For other scenarios, the failure frequency has been estimated using parts count approach. The

total leak frequency for any scenario is estimated by counting the number of each type of

component in the section. This process is called “Parts Count”. The generic leak frequencies

are then multiplied by the number of corresponding components in each isolatable section to

obtain the overall leak frequency for that section.

The calculated frequencies are given here below –




| LIKELIHOOD ESTIMATION| of 54

Table 10 Estimated failure frequency




| RISK ANALYSIS| of 54

7 RISK ANALYSIS

This section deals with the risk assessment of Terminal installed at LPG Bottling Plant,

Raipur. The risk of LPG Bottling Plant, Raipur is calculated based on consequences, parts

count, failure frequency, ignition sources etc.

A Quantitative Risk Analysis (QRA) is used to determine the risk caused by the use,

handling, transport and storage of hazardous substances. The results of the QRA are, for

example, used to assess the acceptability of the risk in relation to the benefits of the activity,

to evaluate new developments on and off-site, to estimate the benefit of risk-reducing

countermeasures and to determine zoning distances around an activity for land-use planning.

QRAs are used to demonstrate the risk caused by the activity and to provide the competent

authorities with relevant information to enable decisions on the acceptability of risk related to

developments on site, or around the establishment or transport route.

7.1 Risk Contours

Location specific individual risk (LSIR) is a measure of the risk exposure of an individual

who is continuously present at a particular location for the whole year.

This is a graphical representation of the risk estimated. Individual risk estimated for LPG

Bottling Plant, Raipur is superimposed on layout and has illustrated below,





Figure 3 Risk Contour for LPG Bottling Plant, Raipur

It can be seen that the risk level of 1E-03/avg year is surrounded to the LPG Bulltes.

Above figure shows the risk impact of the entire facility. It can be seen easily that though the

risk contour goes beyond the facility is 10E-06/avg year, there is no other populated facility

which will get affected.

0.0 0.4 0.8

km





7.2 FN Curve

The FN Curve shows the frequency (F) with which events cause N or more fatalities. F-N

curve for risk posed by LPG Bottling Plant, Raipur on public surrounding is given here

below. The risk is well within ALARP limits

Figure 4 FN Curve for LPG Bottling Plant, Raipur

7.3 IRPA and PLL

Individual Risk per Annum (IRPA) and Potential Loss of Life (PLL) are estimated based on

the LSIR at the locations. Figure above shows that the risk at the office building is less than

1E-07/avg year. Therefore the IRPA and PLL also fall under broadly acceptable region.

7.4 Conclusion

The risk analysis shows that the risk is below 1E-04/avg year. After benchmarking the risk

against PNGRB’s Individual Risk Acceptance criteria, the risk is within ALARP or Tolerable

Region – (Risk is tolerated only – High, investigate alternatives)region which means that

normal precautions shall be maintained.





However, in case of emergency there should be availability of the fire fighting system to

control fire and also the vehicles to escape from hazardous area.

7.5 Recommendations

The facility handles storage and handling of LPG which is highly inflammable in nature.

Considering the hazard associated with storage and handling of LPG, state-of-art safety and

security system has to be conceived to eliminate the hazard.

1. Safety as a consideration; the whole Tank Farm must be automated in order to avoid

delays in mitigating the risks unlike in manual operations.

2. HAZOP study shall be conducted for LPG Bottling Plant, Raipur.

3. Periodic preventive maintenance of pumps, valves, flanges, nozzles, flame arrestors,

breather valves etc. must be done. This preventive maintenance includes:

a. Regular inspection of all pumps checking for mechanical seal to prevent leakages and

fugitive emission.

b. Regular inspection of storage tanks checking for leaks due to cracks, spillages,

corrosion/erosion etc.

c. Regular inspection of flame arrestors and breather valve checking for corrosion.

d. Periodic functional tests of all valves ( isolation valves or any other valves installed

along the pipeline)

e. Checking of storage areas for accumulation of any hazardous or combustible material.

f. Safety devices and control instruments to be calibrated once in a year.

4. Fire & Gas detection system must be installed within one meter radius of tank farm

area.

5. Flameproof Motors for unloading near flammable storage tank should be provided with

double earthing.

6. At every tank farm its license number, storage capacity & name of the chemicals should

be displayed at the entrance.

7. There should be good communication system available near tank farm area to the

control room, and it should be flameproof.

8. A telephone should be provided which is freely available and readily accessible for the

reporting of accidents or emergency situations. The emergency telephone numbers





should include the fire department, ambulance service, emergency response team,

hospital and police.

9. Periodic On Site Emergency Mock Drills and occasional Off Site Emergency Mock

Drills must be conducted, so that the staff is trained and are in a state of preparedness to

tackle any emergency.

10. Safe operating procedure to be prepared for hazardous processes and material handling

process.

11. Operating personnel should be adequately trained.

12. Work permit system must be implemented mandatorily for hazardous work in the plant.

13. Safety manual and Public awareness manual needs to be prepared and distributed to all

employees and nearby public.

14. Fire & Safety organization setup to be planed and implemented for better plant process

safety.

15. Security circuit containing fusible plugs to detect heat/fire and thereby closing ROVs in

vase of fire.

16. Fire water deluge and sprinkler system for spheres and mounded vessels.

17. LPG Storage vessel pressure safety valves designed for fire case.

18. Gas detectors at vantage points near LPG Storage vessel to detect any gas leak and give

alarm.

19. Dyke of small height at the LPG storage to collect LPG spillage with the floor at the

bottom of LPG Storage vessel sloping away from Storage vessels so that LPG will not

form a pool below the Storage vessel itself.

20. All the ROVs should be fire safe certified and CCOE certified for SOV.

21. Emergency push buttons should be provided in LPG control room and also in field at

safe location for manual actuation of emergency shutdown interlock by the operator.

22. LPG transfer pumps should have double mechanical seal type with low level indication

and high pressure indication in field at seal pot. Low level alarm and high pressure

alarm should be available in LPG control room for monitoring the status of level and

high pressure for pump operation, accordingly action should be initiated for running of

LPG Pump.





23. For additional safety, in case of any rupture in the discharge line of LPG Transfer

Pump, alarm should be received in the control room and LPG pumps should

automatically stop running.

24. Water sprinkler arrangement should be always in working condition at the Bullet top

exposed domes / structure, Horton LPG Storage vessels and pumps area.

25. Entire storage and handling facility should be covered under fire hydrant and monitor

loop.

26. In case of flame detection in pump house and LPG Storage area, action should be

initiated through various interlocks for closing of all ROVs located in LPG mounded

vessels outlet line, inlet line, vapour balance line, saturation line and pump minimum

flow line. Sequentially, Deluge Valve will open, Marcaptan Dosing Pump will trip and

also LPG pumps will trip. Accordingly, fire water sprinkler system will actuate

automatically as per logic.

27. Actuation of pressure switch due to quartzoid bulb failure on any of fire detection loop

should give audio-visual alarm at the LPG control room, fire station and security gate

indicating fire.

28. ROV should be manually auto reset type. All DV’s should be ready for taking next

signal immediately after one operation is over, without any further interruption or

manual reset. The Deluge valve position (Opened/Closed) should be indicated by

proximity sensor.

29. Suitable corrosion protection for internal and external surface of mounded storage

vessel should be provided.

30. Cathodic protection should be provided for mounded storage vessels on the external

surface. 31. In order to reduce the frequency of failures and consequent risk, codes, rules and standards

framed e.g. OISD 144, SMPV rules (Unfired), gas cylinder rules etc. should be strictly followed

with respect to construction of new facilities.

32. There should be no depression or low lying areas in the plant in order to avoid accumulation of

LPG vapour and consequent hazard.

33. Safety valves located on the storage vessels and other places must be tested regularly. The block

valves before safety valve must always be kept in open condition when safety valves are in





position. It is desirable to provide a chain and lock to ensure that the block valve is not

inadvertently kept closed when safety valve is in position.

34. Vehicular traffic as well as entry of personnel inside the plant area must be restricted.

35. Smoking within the premises should be strictly prohibited. Use of naked light or hot work must

be restricted to the areas designated for the purpose.

36. The sprinkler system including quartzoid bulbs, heat detectors and remote operated valves must

be checked regularly for timely actuation of the safety system. LPG gas detection system should

be checked regularly.

37. The DG sets must be periodically tested on load to ensure that it remains always in operating

condition.

38. Training of all the employees for fire fighting and use of safety apparatus must be conducted

regularly. Mock drills should be conducted at regular intervals keeping liaison with local

administration and fire-fighting facilities available in the area.

39. Safety Audits must be regularly done as per norms & recommendations of OISD.

40. Inspection and testing of the major equipments e.g. LPG storage, LPG pumps and compressors

etc. should be done at regular intervals for ensuring their health and condition monitoring.

41. Mutual aid agreement should be done with nearby industries. Also agreement shall be made

with hospitals, fire services, nursing homes for help during emergency.

42. Procurement of materials, construction & erection of the plant should be done as per

international codes & practices.

43. Proper lighting system should be done in the plant so that plant personnel can approach in any

part of the plant during night.

44. Disaster Management plan which has been prepared for the plant should be updated to cover the

proposed refrigerated LPG storage and handling facilities along with proposed mounded

vessels.




| Dispersion Contours| of 54

8 DISPERSION CONTOURS

8.1 1350 MT Horton Sphere - 1

indian oil corporation limited quantitative...

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