INDIAN OIL CORPORATION LIMITED Quantitative...
Transcript of 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| Page 2 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.
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Engineering asserts and retains all Copyright, and other Intellectual Property Rights, in and
over the Report and its contents.
Quantitative Risk Assessment Report
LPG Bottling Plant, Raipur
Polite/IND/2018/IOCL – Raipur || Rev – 00 || Issue: March 2018
| Document Control Sheet| Page 3 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.
Quantitative Risk Assessment Report
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| Abbreviations| Page 4 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
Quantitative Risk Assessment Report
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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
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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
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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
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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
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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.
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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.
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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
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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 –
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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.
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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
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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
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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,
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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
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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
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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
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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 –
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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.
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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.
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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
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| CONSEQUENCE ANALYSIS| Page 24 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.
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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)
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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
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SN Scenario ID Description of scenario
Leak Size in mm
Flammable distances in m Conc. 2F 5D
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
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| CONSEQUENCE ANALYSIS| Page 28 of 54
SN Scenario ID Description of scenario
Leak Size in mm
Flammable distances in m Conc. 2F 5D
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
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SN Scenario ID Description of scenario
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
Loss of containment of LPG from 100
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
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| CONSEQUENCE ANALYSIS| Page 30 of 54
SN Scenario ID Description of scenario
Leak Size in mm
Flammable distances in m Conc. 2F 5D
LFL Frac 96.86 160.45
10 IS10
Loss of containment of LPG from 100
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
Loss of containment of LPG from 100
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
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| CONSEQUENCE ANALYSIS| Page 31 of 54
SN Scenario ID Description of scenario
Leak Size in mm
Flammable distances in m Conc. 2F 5D
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
Loss of containment of LPG from 450
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
Loss of containment of LPG from 450
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
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| CONSEQUENCE ANALYSIS| Page 32 of 54
SN Scenario ID Description of scenario
Leak Size in mm
Flammable distances in m Conc. 2F 5D
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
Loss of containment of LPG from 450
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
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| CONSEQUENCE ANALYSIS| Page 33 of 54
SN Scenario ID Description of scenario
Leak Size in mm
Flammable distances in m Conc. 2F 5D
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
Loss of containment of
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
Loss of containment of
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
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| CONSEQUENCE ANALYSIS| Page 34 of 54
SN Scenario ID Description of scenario
Leak Size in mm
Flammable distances in m Conc. 2F 5D
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
SN Scenario ID Description of scenario
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
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SN Scenario ID Description of scenario
Leak Size in
mm
Jet Fire distances in m Radiation
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
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SN Scenario ID Description of scenario
Leak Size in
mm
Jet Fire distances in m Radiation
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
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| CONSEQUENCE ANALYSIS| Page 37 of 54
SN Scenario ID Description of scenario
Leak Size in
mm
Jet Fire distances in m Radiation
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
9 IS09 Loss of containment of
LPG from 100 MT Horton Sphere 2
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
10 IS10 Loss of containment of
LPG from 100 MT Horton Sphere 3
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
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| CONSEQUENCE ANALYSIS| Page 38 of 54
SN Scenario ID Description of scenario
Leak Size in
mm
Jet Fire distances in m Radiation
kw/m2 2F 5D
100 4 14.62 14.58
12.5 11.04 11.77
37.5 8.50 9.56
11 IS11 Loss of containment of
LPG from 100 MT Horton Sphere 4
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
12 IS12 Loss of containment of
LPG from 100 MT Horton Sphere 5
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
13 IS13 Loss of containment of
LPG from 450 MT Horton Sphere 6
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
14 IS14 Loss of containment of
LPG from 450 MT Horton Sphere 7
5 4 2.30 2.30
12.5 2.06 2.06
37.5 NR NR
25 4 12.26 12.70
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SN Scenario ID Description of scenario
Leak Size in
mm
Jet Fire distances in m Radiation
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
15 IS15 Loss of containment of
LPG from 450 MT Horton Sphere 8
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
16 IS16 Loss of containment of
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
17 IS17 Loss of containment of
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
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SN Scenario ID Description of scenario
Leak Size in
mm
Jet Fire distances in m Radiation
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
19 IS19 Loss of containment of
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
FBR: Full Bore Rupture
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
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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
SN Scenario ID Description of scenario
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
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SN Scenario ID Description of scenario
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
FBR: Full Bore Rupture
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
SN Scenario ID Description of scenario
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
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SN Scenario ID Description of scenario
Leak Size in
mm
Fireball distances in m Radiation
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
9 IS9 100 MT Horton Sphere 2 FBR 4 300.53 263.78
12.5 160.19 139.02 37.5 50.61 22.69
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SN Scenario ID Description of scenario
Leak Size in
mm
Fireball distances in m Radiation
kw/m2 2F 5D
10 IS10 100 MT Horton Sphere 3 FBR 4 300.53 263.78
12.5 160.19 139.02 37.5 50.61 22.69
11 IS11 100 MT Horton Sphere 4 FBR 4 300.53 263.78
12.5 160.19 139.02 37.5 50.61 22.69
12 IS12 100 MT Horton Sphere 5 FBR 4 300.53 263.78
12.5 160.19 139.02 37.5 50.61 22.69
13 IS13 450 MT Horton Sphere 6 FBR 4 1024.52 899.27
12.5 546.11 473.94 37.5 172.55 77.35
14 IS14 450 MT Horton Sphere 7 FBR 4 1024.52 899.27
12.5 546.11 473.94 37.5 172.55 77.35
15 IS15 450 MT Horton Sphere 8 FBR 4 1024.52 899.27
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
FBR: Full Bore Rupture
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.
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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 –
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Table 10 Estimated failure frequency
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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,
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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
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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.
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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
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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.
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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
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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.
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8 DISPERSION CONTOURS
8.1 1350 MT Horton Sphere - 1