quantitative risk assessment for...indian oil's vast marketing infrastructure of petrol/diesel...

QUANTITATIVE RISK ASSESSMENT

FOR

PROPOSED AUGMENTATION IN LPG BULK STORAGE CAPACITY

AT LPG BOTTLING PLANT AT MEHATPUR, UNA,

HIMACHAL PRADESH

PREPARED BY

Quantitative Risk Assessment Report of IOCL LPG Bottling Plant, Una

ABBREVIATIONS

AIChE American Institute of Chemical Engineers

ALARP As Low As Reasonably Practicable

IOCL Indian Oil Corporation Ltd

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

LOC Loss of Containment

LPG Liquified Petroleum Gas

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

UFL Upper Flammability Level

Quantitative Risk Assessment Report of IOCL LPG Bottling Plant, Una 1

Contents

Definitions.................................................................................................................................. 5

1 INTRODUCTION ............................................................................................................. 7

1.1 Brief description of Nature, Size and Location of the project .................................... 9

1.2 Project Objective ....................................................................................................... 10

2 METHODOLOGY .......................................................................................................... 11

2.1 Methodology ............................................................................................................. 11

2.2 QRA Approach .......................................................................................................... 11

2.2.1 Result Interpretation........................................................................................... 11

2.2.2 Risk Criteria ....................................................................................................... 12

2.3 Risk............................................................................................................................ 13

2.4 Individual Risk Criteria (IR) ..................................................................................... 13

2.5 Presentation of Risk Results ...................................................................................... 13

2.5.1 Location Specific Individual Risk (LSIR) ......................................................... 13

2.5.2 Individual Risk per Annum (IRPA) ................................................................... 14

2.5.3 Potential Loss of Life (PLL) .............................................................................. 14

3 HAZARD IDENTIFICATION ........................................................................................ 15

3.1 Hazards associated with storage tanks ...................................................................... 15

3.2 Hazard Categories ..................................................................................................... 15

3.3 Hazardous Properties................................................................................................. 15

3.4 Scenarios ................................................................................................................... 16

3.4.1 List of identified Scenarios ................................................................................ 17

3.5 Population Data ......................................................................................................... 17

3.6 Ignition sources ......................................................................................................... 18

3.7 Climatic Conditions................................................................................................... 18

3.7.1 Meteorological Data........................................................................................... 18

3.7.2 Atmospheric Stability Classes ........................................................................... 19

4 EVENTS AND IGNITION PROBABILITY .................................................................. 20

4.1 Event Tree ................................................................................................................. 20

4.2 Consequential Events ................................................................................................ 21

4.2.1 Jet Fire ................................................................................................................ 21

4.2.2 Pool Fire ............................................................................................................. 21


4.2.3 Flammable Gas Dispersion / Flash Fire ............................................................. 22

4.2.4 Vapour Cloud Explosion.................................................................................... 22

4.2.5 BLEVE ............................................................................................................... 22

4.3 Ignition Probability ................................................................................................... 22

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

5.1 Modes of failure ........................................................................................................ 24

5.2 Impact Criteria........................................................................................................... 25

5.2.1. Impact due to fire ................................................................................................... 25

5.2.2. Impact due to explosion/dispersion ........................................................................... 26

5.3 Initial Release Rates .................................................................................................. 26

5.4 Flammable Gas Dispersion ....................................................................................... 27

5.5 Radiation Distances due to Jet Fire ........................................................................... 29

5.6 Radiation Distances due to Pool Fire ........................................................................ 31

5.7 Overpressure Distances due to Explosion ................................................................ 32

5.8 Boiling liquid expanding vapor explosion (BLEVE) ................................................ 34

5.8.1 Fireball due to BLEVE in Road Tanker ............................................................ 34

6 LIKELIHOOD ESTIMATION ........................................................................................ 35

6.1 Failure Frequencies ................................................................................................... 35

7 RISK ANALYSIS ............................................................................................................ 37

7.1 Risk Contours ............................................................................................................ 37

7.2 FN Curve ................................................................................................................... 39

7.3 IRPA and PLL ........................................................................................................... 39

7.4 Conclusion ................................................................................................................. 40

7.5 Recommendations ..................................................................................................... 40

8 Dispersion Contours......................................................................................................... 42

List of Tables

Table 1: Project and Project Proponent Description .................................................................. 8

Table 2: Typical Pasquill Stability classes............................................................................... 19

Table 3: Ignition Probabilities as used in PHAST. .................................................................. 23

Table 4: Leak sizes considered ................................................................................................ 24

Table 5: Thermal Radiation Impact Criteria for Personnel ..................................................... 25


Table 6: Thermal Radiation Impact Criteria for Equipment .................................................... 25

Table 7: Flammable (LFL) dispersion distances ..................................................................... 27

Table 8: Jet fire radiation distances ......................................................................................... 30

Table 9 Pool fire radiation distances .................................................................................. 32

Table 10 Overpressure Distances due to Explosion .............................................................. 32

Table 11 Fireball (BLEVE) distance for Road Tanker ........................................................... 34

Table 12:Estimated failure frequency ...................................................................................... 36

List of Figures

Figure 1: Connectivity Map ..................................................................................................... 10

Figure 2: Risk Acceptance Criteria .......................................................................................... 12

Figure 3: Event tree for Continuous release with rainout (from PHAST software) ................ 21

Figure 4 Risk Contour for LPG Bottling Plant, Una ........................................................... 38

Figure 5 FN Curve for LPG Bottling Plant, Una ................................................................ 39

Figure 6 Flash fire dispersion contour due to 25 mm leak at Tanker ................................. 42

Figure 7 Jet fire dispersion contour due to 25 mm leak at Tanker ...................................... 43

Figure 8 Flash fire dispersion contour due to 100 mm leak at Tanker .............................. 44

Figure 9 Jet fire dispersion contour due to 100 mm leak at Tanker .................................... 45

Figure 10 Overpressure distances due to BLEVE in Road Tanker .................................... 46

Figure 11 Flash fire dispersion contour due to 25 mm leak at Piping from unloading arm

to inlet of LPG Bullet ............................................................................................................... 47

Figure 12 Jet fire dispersion contour due to 25 mm leak at Piping from unloading arm to

inlet of LPG Bullet ................................................................................................................... 48

Figure 13 Flash fire dispersion contour due to 100 mm leak at Piping from unloading arm

to inlet of LPG Bullet ............................................................................................................... 49

Figure 14 Jet fire dispersion contour due to 100 mm leak at Piping from unloading arm to

inlet of LPG Bullet ................................................................................................................... 50

Figure 15 Flash fire dispersion contour due to 25 mm leak at Piping from LPG Bullet to

Tanker passing through Compressors ...................................................................................... 51


Figure 16 Jet fire dispersion contour due to 25 mm leak at Piping from LPG Bullet to


Figure 17 Flash fire dispersion contour due to 100 mm leak at Piping from LPG Bullet to




Figure 27 Flash fire dispersion contour due to 25 mm leak at Piping from outlet of LPG

Bullets to suction of LPG pumps ............................................................................................ 55

Figure 28 Jet fire dispersion contour due to 25 mm leak at Piping from outlet of LPG

Bullets to suction of LPG pumps ............................................................................................. 56

Figure 29 Flash fire dispersion contour due to 100 mm leak at Piping from outlet of LPG

Bullets to suction of LPG pumps ............................................................................................ 57


Bullets to suction of LPG pumps ............................................................................................. 58

Figure 31 Flash fire dispersion contour due to 25 mm leak at Piping from discharge of

LPG pumps to Carousals Filling gun (LPG Cylinder filling operation) ................................. 59

Figure 32 Jet fire dispersion contour due to 25 mm leak at Piping from discharge of LPG

pumps to Carousals Filling gun (LPG Cylinder filling operation) ......................................... 60


LPG pumps to Carousals Filling gun (LPG Cylinder filling operation) ................................ 61

Figure 34 Jet fire dispersion contour due to 100 mm leak at Piping from discharge of LPG

pumps to Carousals Filling gun (LPG Cylinder filling operation) ......................................... 62


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

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.


1 INTRODUCTION

M/s. Indian Oil Corporation Limited (IOCL) is a government of India enterprise with a Navratna

status, and a Fortune 500 and Forbes 2000 company. Incorporated as IOCL on 1st September,

1964 Indian Oil and its subsidiaries account for approximately 48% petroleum products market

share, 34% national refining capacity and 71% downstream sector pipelines capacity in India. It

is India‘s flagship national oil company and downstream petroleum major thus being India‘s

largest commercial enterprise. As the flagship national oil company in the downstream sector,

Indian Oil reaches precious petroleum products to millions of people every day through a

countrywide network of about 35,000 sales points. They are backed for supplies by 167 bulk

storage terminals and depots, 101 aviation fuel stations and 91 Indane (LPG) bottling plants.

Indian Oil's vast marketing infrastructure of petrol/diesel stations, Indane (LPG) distributorships,

SERVO lubricants and greases outlets and large volume consumer pumps are backed by bulk

storage terminals and installations, inland depots, aviation fuel stations, LPG bottling plants and

lube blending plants amongst others. The countrywide marketing operations are coordinated by

16 State Offices and over 100 decentralized administrative offices

IOCL is a premier public sector company in the Oil & Gas Sector and is engaged in the business

of refining and retailing of petroleum products including LPG in the country. It is the leading

Indian corporate in the Fortune 'Global 500' listing, ranked at the 83rd position in the year 2012.

IOCL is having about 91 LPG bottling plants, which serve every corner of the country. Indane

(the trade name of LPG of IOCL) is supplied to the consumers through a network of about 5,456

distributors (51.8% of the industry).The growth in demand of LPG for domestic purpose is

increasing at a rapid pace.

Bulk Liquefied Petroleum Gas (LPG) is received in a bullet tanker – truck from IOCL Jalandhar

and Loni unloaded by using vapor compressors and stored in Mounded Bullets. The empty

cylinders are unloaded in the unloading shed and sent by means of conveyors to the carousel for

filling them with LPG. LPG is filled in cylinders of capacity 5 kg, 14.2 kg, 19.0 kg and 47.5 kg.

LPG from the storage area is pumped to the filling machine by means of LPG pumps for filling

the cylinders. After filling cylinders and subsequent checks, the filled cylinders are sent to the

filled cylinder shed and loaded on to the trucks for dispatch to the LPG distributors to use for

house hold and industrial purposes. The details of the Project and Proponents are as mentioned in

table given below –


Table 1: Project and Project Proponent Description

Name of Project Proposed augmentation in LPG Bulk Storage capacity at LPG

Bottling Plant at Mehatpur, Una, Himachal Pradesh by M/s

Indian Oil Corporation Ltd.

Project Proponent M/s Indian Oil Corporation Limited

Name, contact number and

address of Project Proponent

M/s Indian Oil Corporation Limited

Shri Jyotiprakash Chakraborty

Sr. Mgr(LPG-E), PSO

Indian Oil Corporation Limited,

Punjab State Office,

Indian Oil Bhavan, Plot No. 3A, Sector-19A,

Madhya Marg, Chandigarh - 160 019

Location of the Project

Village : Raipur Sahoran

District : Una

Taluka : Una

State : Himachal Pradesh

Latitude : 31°23'43.72"N

Longitude : 76°19'40.43"E

Name, contact number and

address of Consultant

Environmental Consultants :

M/s. Ultra-Tech Environmental Consultancy & Laboratory

(An ISO 9001-2008 Company, Accredited by NABET, Lab:

recognised by MOEF&CC, GoI)

Unit No. 206, 224, 225, Jai Commercial Complex,

Eastern Express Highway, Opp. Cadbury Factory,

Khopat, Thane (W) – 400601

Tel.: 91-22-25342776, 25380198, 25331438

Fax : 91-22-25429650

Email: [email protected]

Website : www.ultratech.in

Size of proposed project activity 13.17 ha (32.56 acres)

Plant Overview 1. LPG bottling plant

2. Distribute bulk products by road (by tank lorries )

http://www.ultratech.in/


Category of Project i.e. ‗A‘ or

‗B‘

Category ‗B‘

Proposed capacity/ area/ length/

tonnage to be handled/ command

area/ lease area/ number of wells

to be drilled

Proposed expansion from 900 MT storage capacity of LPG to

2100 MT by installing 2 x 600 = 1200 MT of additional

Mounded LPG Bullets

1.1 Brief description of Nature, Size and Location of the project

The project activity is augmentation in LPG Bulk Storage capacity at LPG Bottling Plant at

Mehatpur, Una. As per the Environment Impact Assessment (EIA) Notification dated 14th

September, 2006 as amended, the proposed project falls under 'Type 6b - Isolated Storage and

Handling of Hazardous Chemicals’ (As per threshold planning quantity indicated in column 3 of

schedule 2 and 3 of MSIHC Rules 1989 amended 2000), which requires preparation of an

Environmental Impact Assessment (EIA) Report.

This EIA Report addresses the environmental impacts of the proposed project and proposes the

mitigation measures for the same. The report is prepared, based on the Standard Terms of

Reference (ToR) for EIA/EMP Report for Projects requiring Environmental Clearance (EC) for

Isolated Storage & Handling of Hazardous Chemicals project by Ministry of Environment &

Forests & Climate Change (MoEF&CC).

The Bottling plant is located at Una district in Himachal Pradesh. The total plot area of the LPG

Plant facility is approximately 13.17 hectare (32.56 acres). The proposed augmentation shall be

carried out within the premises of the Bottling Plant. The site is easily accessible by road. The

nearest railway station is Rai Mehatpur Railway Station at approximately 0.4 km. The nearest

airport is Chandigarh Airport at about 118 Km.


Figure 1: Connectivity Map

1.2 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, Una.

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.


2 METHODOLOGY

2.1 Methodology

Methodology adopted for risk assessment of LPG Bottling Plant, Una 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 10.2

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 10-5 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 –

IRPA

10-3/yr

10-4/yr

10-5/yr

10-6/yr

Intolerable

The ALARP or Tolerable

region (Risk is tolerated only)

Broadly Acceptable region

(no need for detailed working todemonstrate ALARP)

Fundamental improvements needed.Only to be considered if there are no

alternatives and people are well informed

Too high, significant effort required toimprove

High, investigate alternatives

Low, consider cost-effective alternatives

Negligible, maintain normal precautions

Figure 2: 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, Una.

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


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 explosion risk. As there is no toxic material being

handled at facility, there is no toxic risk envisaged

3.3 Hazardous Properties

Combustion of hazardous substance occurs when flammable vapours released from the surface of

the substance ignite. The amount of flammable vapour given off from a hazardous substance, and

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

substance, 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 substance

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

These are the various materials are handled in the facility & 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 %

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 vapourto 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

Note: In the present facility, mounded bullets are submerged so there is negligible possibility

of bullet leakage or rupture. HSD is also stored underground, so negligible possibility of

leakage or rupture

3.4.1 List of identified Scenarios

SN Section Number Section Description

1 IS1 Road Tanker

2 IS2 Piping from unloading arm to inlet of LPG Bullet

3

IS3

Piping from LPG Bullet to Tanker passing through

Compressors

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

5

IS5

Piping from discharge of LPG pumps to Carousals Filling

gun (LPG Cylinder filling operation)

6 IS6 Diesel Tank Transfer pump discharge line

3.5 Population Data

Plant operations are carried out only during day time in general shift.

The distribution of personnel in the IOCL Una LPG storage bottling plant is shown in Table

given herebelow

SN Location I shift II shift III shift General

shift Total

1 Bullet Area 0 0 0 0 0

2 Pump House 1 1 0 0 2

3 TT Gantry 5 5 0 0 10


SN Location I shift II shift III shift General

shift Total

4 Valve Changing

shed 1 1 0 0 2

5 Filling Shed 15 15 2 0 32

6 Storage Shed 1 1 0 0 2

7 Unloading Shed 7 7 1 0 15

8 Loading Shed 7 7 0 0 14

9 MCC 1 1 0 2 4

10 Retesting Shed 0 0 0 21 21

11 Admin Building

Area 0 0 0 10 10

12 Planning Room 2 2 0 0 4

13 Security Cabin 3 3 3 1 10

Total 43 43 6 34 126

3.6 Ignition sources

Ignition sources are strictly controlled in the LPG bottling plant area. All electrical equipment

and fittings are flame-proof type. No vehicle is allowed inside the premises without approved

spark arrestor in the engine exhaust.

The following sources of ignition are considered in the risk analysis.

1. Substation

2. Diesel generator

3. LT yard/ Transformer

4. Canteen

3.7 Climatic Conditions

3.7.1 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.

3.7.2 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 2: 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


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 3: 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.

4.2.4 Vapour Cloud Explosion

Vapour cloud explosion is the result of flammable materials in the atmosphere, a subsequent

dispersion phase, and after some delay an ignition of the vapour cloud. Turbulence is the

governing factor in blast generation, which could intensify combustion to the level that

will result in an explosion. Obstacles in the path of vapour cloud or when the cloud finds

a confined area often create turbulence. Insignificant level of confinement will result in a

flash fire. The VCE will result in overpressures.

It may be noted that VCEs have been responsible for very serious accidents involving

severe property damage and loss of lives.

4.2.5 BLEVE

A boiling liquid expanding vapor explosion (BLEVE) is an explosion caused by the

rupture of a vessel containing a pressurized liquid that has reached temperatures above

its boiling point.

4.3 Ignition Probability

There are 2 main types of ignitions, namely:

https://en.wikipedia.org/wiki/Explosion

https://en.wikipedia.org/wiki/Pressure

https://en.wikipedia.org/wiki/Liquid

https://en.wikipedia.org/wiki/Boiling_point


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 3: Ignition Probabilities as used in PHAST.

Type and Size of Release Type of Material Released

Continuous Instantaneous

K0 K1 K2 K3 K4

Gas; liquid: Tfl< 0oC liquid: liquid: liquid: liquid

Reactivity: Reactivity: Tfl<

21oC

Tfl<

55oC

Tfl<

100oC

Tfl>

100oC 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


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

Loss of containment from the system can lead to undesired consequences such as fire or

explosion. The consequencial effects may vary depending on the leak sizes or rupture.

Following table shows various leak sizes along with their significance.

Table 4: 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. Impact due to fire

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

levels listed includes solar radiation of 1 kW/m2.

Table 5: 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 6: 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.

5.2.2. Impact due to explosion/dispersion

A Vapour cloud Explosion (VCE) results when a flammable vapor is released, its mixture

with air will form a flammable vapour cloud. If ignited, the flame speed may accelerate to

high velocities and produce significant blast overexposure.

The damage effects due to 30mbar, 100mbar & 300mbar are reported in terms of distance

from the overpressure source.

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

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

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

Table7: Damage Due To Overpressures

Peak Overpressure, bar Damage Type

0.83 Total destruction

0.30 Heavy damage, nearly complete destruction of

houses

0.27 Cladding of light industrial building ruptures

0.2 Steel frame buildings distorted and pulled from

foundations

0.16 Lower limit of serious structural damage

0.14 Partial collapse of walls and roofs of houses

0.027 Limited minor structural damage

0.01 Typical pressure of glass breakage

5.3 Initial Release Rates

LOC at the facility 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.


Material 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 7: Flammable (LFL) dispersion distances

SN Scenario

ID

Scenario Description Leak Size

in mm

Flammable distances in m

Conc. 2F 5D

1

IS1

Road Tanker

5

UFL 1.63 1.59

LFL 6.80 5.41

LFL Frac 13.56 7.98

25 UFL 7.96 7.41

LFL 54.84 50.07

LFL Frac 128.54 103.22

100

UFL 40.09 39.54

LFL 237.14 289.97

LFL Frac 498.62 448.14

Catastrophic UFL 67.35 66.87


SN Scenario

ID


in mm


Conc. 2F 5D

Rupture LFL 381.49 470.09

LFL Frac 560.09 651.52

2

IS2

Piping from unloading

arm to inlet of LPG

Bullet

5 UFL 1.63 1.59

LFL 6.80 5.41

LFL Frac 13.56 7.98

25

UFL 7.96 7.41

LFL 54.84 50.07

LFL Frac 128.54 103.22

100 UFL 40.09 39.54

LFL 252.23 301.19

LFL Frac 374.86 427.13

FBR

UFL 67.35 66.87

LFL 298.15 369.46

LFL Frac 419.34 484.34

3

IS3

Piping from LPG

Bullet to Tanker

passing through

Compressors

5 UFL 1.82 1.78

LFL 7.62 6.00

LFL Frac 16.21 9.50

25

UFL 8.93 8.28

LFL 63.16 59.54

LFL Frac 143.71 119.19

100 UFL 46.26 45.71

LFL 265.70 328.13

LFL Frac 386.23 444.55

FBR

UFL 47.13 46.59

LFL 267.27 333.56

LFL Frac 388.04 446.38

LFL Frac 891.12 1127.6

0

4

IS4

Piping from outlet of

LPG Bullets to suction

of LPG pumps

5 UFL 1.68 1.65

LFL 7.06 5.58

LFL Frac 14.32 8.39

25 UFL 8.27 7.65

LFL 57.16 53.10

LFL Frac 133.15 107.83

100 UFL 41.81 41.12

LFL 241.28 301.08

LFL Frac 351.49 399.75

FBR

UFL 127.14 126.97

LFL 335.22 421.79


SN Scenario

ID


in mm


Conc. 2F 5D

LFL Frac 441.25 516.45

5

IS5

Piping from discharge

of LPG pumps to

Carousals Filling gun

(LPG Cylinder filling

operation)

5 UFL 0.24 0.24

LFL 1.17 1.09

LFL Frac 2.14 1.82

25

UFL 1.13 1.14

LFL 5.58 4.81

LFL Frac 10.23 7.46

100 UFL 4.47 4.41

LFL 27.66 25.52

LFL Frac 67.29 68.46

FBR

UFL 6.79 6.64

LFL 47.56 47.15

LFL Frac 113.36 122.90

Notes:

NR: Not Reached

FBR: Full Bore Rupture

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 8: Jet fire radiation distances

SN Scenario

ID

Scenario

Description

Leak Size

in mm

Jet Fire distances in m

Radiation

kw/m2 2F 5D

1

IS1

Road Tanker

5 4 15.53 13.44

12.5 12.41 10.23

37.5 10.43 8.21

25

4 67.72 58.90

12.5 53.84 44.82

37.5 45.53 36.45

100 4 235.82 204.96

12.5 185.28 154.72

37.5 155.24 124.88

2

IS2

Piping from

unloading arm to

inlet of LPG Bullet

5 4 9.59 10.71

12.5 NR 6.24

37.5 NR NR

25

4 44.94 39.29

12.5 21.15 23.66

37.5 NR 11.00

100 4 135.78 116.29

12.5 61.45 69.88

37.5 NR 25.16

3

IS3

Piping from LPG

Bullet to Tanker

passing through

Compressors

5

4 10.86 11.83

12.5 NR 6.91

37.5 NR NR

25

4 49.47 42.99

12.5 23.13 25.96

37.5 NR 11.50

100 4 149.04 127.61

12.5 66.70 76.16

37.5 NR 25.75


SN Scenario

ID

Scenario

Description

Leak Size

in mm

Jet Fire distances in m

Radiation

kw/m2 2F 5D

4

IS4

Piping from outlet

of LPG Bullets to

suction of LPG

pumps

5

4 9.96 11.08

12.5 NR 6.45

37.5 NR NR

25 4 46.28 40.39

12.5 21.75 24.35

37.5 NR 11.18

100 4 139.70 119.64

12.5 63.03 71.76

37.5 NR 25.40

12.5 123.22 143.57

37.5 7.49 42.02

5

IS5

Piping from

discharge of LPG

pumps to Carousals

Filling gun (LPG

Cylinder filling

operation)

5

4 NR NR

12.5 NR NR

37.5 NR NR

25 4 4.00 7.36

12.5 NR NR

37.5 NR NR

100

4 20.81 28.19

12.5 NR 9.77

37.5 NR NR

Notes:

NR: Not Reached


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 9 Pool fire radiation distances

SN Scenario

ID Scenario Description

Leak

Size in

mm

Pool fire distances in m

Radiation

kw/m2 2F 5D

1 IS6 Diesel Tank Transfer pump

line

5

4 32.22 35.69

12.5 19.77 24.85

37.5 11.21 11.97

25

4 36.20 39.19

12.5 23.76 28.35

37.5 15.20 15.47

FBR

4 38.50 41.48

12.5 26.05 30.64

37.5 17.49 17.76

NR: Not Reached


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

pump which goes up to 40 m for 4kW/m2 radiation for 5D wind Condition.

5.7 Overpressure Distances due to Explosion

Table 10 Overpressure Distances due to Explosion

SN Scenario

ID Description of scenario

Leak

Size in

mm

Maximum Distance (m) at

Overpressure Level

Overpress

ure in bar 2F 5D

1 IS1 Road Tanker

5mm

0.02068 10.79 10.79

0.1379 2.72 2.72

0.2068 2.13 2.13

25mm

0.02068 32.37 32.37

0.1379 8.15 8.15

0.2068 6.38 6.38

100mm 0.02068 97.12 97.12


SN Scenario


Leak

Size in

mm


Overpressure Level

Overpress

ure in bar 2F 5D

0.1379 24.46 24.46

0.2068 19.14 19.14

Cat Rup

0.02068 291.36 291.36

0.1379 73.37 73.37

0.2068 57.41 57.41

2 IS2

Piping from unloading

arm to inlet of LPG

Bullet

5mm

0.02068 2.28 2.23

0.1379 2.02 1.98

0.2068 0.64 0.63

25mm

0.02068 6.83 6.69

0.1379 6.07 5.95

0.2068 1.92 1.88

100mm

0.02068 13.66 13.39

0.1379 12.14 11.89

0.2068 3.83 3.76

FBR

0.02068 68.3 66.94

0.1379 36.41 35.68

0.2068 11.5 11.27

3 IS3

Piping from LPG Bullet

to Tanker passing

through Compressors

5mm

0.02068 4.55 4.46

0.1379 4.05 3.96

0.2068 1.28 1.25

25mm

0.02068 13.66 13.39

0.1379 12.14 11.89

0.2068 3.83 3.76

100mm

0.02068 27.32 26.77

0.1379 24.27 23.79

0.2068 7.67 7.52

FBR

0.02068 136.6 133.87

0.1379 72.81 71.36

0.2068 23.01 22.55

4 IS4

Piping from outlet of

LPG Bullets to suction

of LPG pumps

5mm

0.02068 5.46 5.35

0.1379 4.85 4.76

0.2068 1.53 1.5

25mm

0.02068 16.39 16.06

0.1379 14.56 14.27

0.2068 4.6 4.51


SN Scenario


Leak

Size in

mm


Overpressure Level

Overpress

ure in bar 2F 5D

100mm

0.02068 32.78 32.13

0.1379 29.13 28.54

0.2068 9.2 9.02

FBR

0.02068 163.92 160.65

0.1379 87.38 85.63

0.2068 27.61 27.06

5 IS5

Piping from discharge

of LPG pumps to

Carousals Filling gun

(LPG Cylinder filling

operation)

5mm

0.02068 2.73 2.68

0.1379 2.43 2.38

0.2068 0.77 0.75

25mm

0.02068 8.2 8.03

0.1379 7.28 7.14

0.2068 2.3 2.25

100mm

0.02068 16.39 16.06

0.1379 14.56 14.27

0.2068 4.6 4.51

FBR

0.02068 81.96 80.32

0.1379 43.69 42.81

0.2068 13.8 13.53

Notes:

NR: Not Reached


Cat Rup: Catastrophic Rupture

5.8 Boiling liquid expanding vapor explosion (BLEVE)

A boiling liquid expanding vapor explosion (BLEVE) is an explosion caused by the rupture

of a vessel containing a pressurized liquid above its boiling point.

5.8.1 Fireball due to BLEVE in Road Tanker

Table 11 Fireball (BLEVE) distance for Road Tanker

Scenario Maximum Distance for BLEVE (Fireball)

Radiation kw/m2 2F 5D

Road Tanker (IS1)

4 376.46 376.46

12.5 187.47 187.47

37.5 NR NR


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 Underground Storage mounded vessels. Under section 2

of Report No. 434 – 3 the failure frequency of Underground/submerged Storage mounded

vessels is 1.1 × 10-7/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 –


Table 12:Estimated failure frequency


7 RISK ANALYSIS

This section deals with the risk assessment of IOCL LPG Bottling Plant installed at Una. The

risk of LPG Bottling Plant, Una 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, Una is superimposed on layout and has illustrated below,


0.00 0.20 0.40

km

Figure 4: Risk Contour for LPG Bottling Plant, Una


It can be seen that the risk level of 1E-04/avg year is surrounded to the LPG Bulltes and LPG

Compressore area.

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-07/avg year, there is no other populated facility

which will get affected.

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, Una on public surrounding is given here below.

The risk is well within ALARP limits

Figure 5: FN Curve for LPG Bottling Plant, Una

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.

LPG detection system provided at LPG handling area shall be tested to initiate an alarm at

its installed location at regular intervals to check its operability.

A regular scheduled plant inspection shall be done for excess flow check valve in the road

tankers and the excess flow check valves on the liquid transfer line to avoid escape LPG

during loading/ unloading operations. OISD-135 on ―Inspection of Loading and

Unloading Hoses‖ for petroleum products shall be followed for inspection and

maintenance of loading/ unloading hoses.

Use of mechanical equipment & tools that easily generate sparks in operation should be

prohibited.

Attention should be given to avoid possible sources of ignition. Ensure strict

implementation of ‗NO SMOKING‘ and ‗NO MOBILE‘ at the facility to minimize

ignition chances. The vehicles entering inside the plant should be ensured to be fitted with

flame arrestors.

It is to be ensured that all the employees are thoroughly trained in emergency procedures.

This will include recognition of alarm signals (initial alarm, emergency, evacuation) and

personal action on instruction to evacuate.

Operating personnel should be adequately trained.

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

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

employees and nearby public.

Water sprinkler arrangement should be always in working condition at the pumps area


compressor area etc.

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

loop.

Small leaks could occur frequently during routine operations like pump seal failure,

sample point valve or drain valve left open, flange leak etc. They should be attended to

immediately as they could escalate.

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

breather valves etc. must be done.

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.

Safety as a consideration; ensure the facility must be automated in order to avoid delays

in mitigating the risks unlike in manual operations.

Loading/unloading operations should be done with proper earthing/bonding.

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

case of fire

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.

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

operating condition.

Ensure selection of electrical/lighting equipment‘s based on HAC (hazardous area

classification).

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

surface.

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.


8 DISPERSION CONTOURS

Figure 6 Flash fire dispersion contour due to 25 mm leak at Tanker


Figure 7 Jet fire dispersion contour due to 25 mm leak at Tanker


Figure 8 Flash fire dispersion contour due to 100 mm leak at Tanker


Figure 9 Jet fire dispersion contour due to 100 mm leak at Tanker


Figure 10 Overpressure distances due to BLEVE in Road Tanker


Figure 11 Flash fire dispersion contour due to 25 mm leak at Piping from unloading

arm to inlet of LPG Bullet


Figure 12 Jet fire dispersion contour due to 25 mm leak at Piping from unloading arm

to inlet of LPG Bullet


Figure 13 Flash fire dispersion contour due to 100 mm leak at Piping from unloading



Figure 14 Jet fire dispersion contour due to 100 mm leak at Piping from unloading



Figure 15 Flash fire dispersion contour due to 25 mm leak at Piping from LPG Bullet

to Tanker passing through Compressors



Tanker passing through Compressors


Figure 17 Flash fire dispersion contour due to 100 mm leak at Piping from LPG Bullet

to Tanker passing through Compressors



Tanker passing through Compressors


Figure 19 Flash fire dispersion contour due to 25 mm leak at Piping from outlet of

LPG Bullets to suction of LPG pumps



Bullets to suction of LPG pumps


Figure 21 Flash fire dispersion contour due to 100 mm leak at Piping from outlet of

LPG Bullets to suction of LPG pumps



Bullets to suction of LPG pumps



LPG pumps to Carousals Filling gun (LPG Cylinder filling operation)


Figure 24 Jet fire dispersion contour due to 25 mm leak at Piping from discharge of



Figure 25 Flash fire dispersion contour due to 100 mm leak at Piping from discharge

of LPG pumps to Carousals Filling gun (LPG Cylinder filling operation)


Figure 26 Jet fire dispersion contour due to 100 mm leak at Piping from discharge of


quantitative risk assessment for...indian oil's vast marketing infrastructure of petrol/diesel...

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