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INDIAN OIL CORPORATION LIMITED

QUANTITATIVE RISK ASSESSMENT (QRA) REPORT

FOR

LPG MOUNDED STORAGE SYSTEM

(EXISTING &PROPOSED)

AT

VISAKHAPATNEM, ANDHRA PRADESH

VIMTA LABS LIMITED

461. 142, IDA Phase-II,Cherlapally

Hyderabad - 500051

REVISION – A2

JUNE 2019

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QRA Report for Existing & New LPG Storage & Bottling Plant

of IOCL Visakhapatnam

CONTENTS Chapter Description Page No.

1. INTRODUCTION 4

2. FACILITYDESCRIPTION 5

3. SCOPE, OBJECTIVE &METHODOLOGY 9

4. QUANTITATIVE RISKANALYSIS 20

5. CONCLUSIONS & RECOMMENDATIONS Error! Bookmark not defined.

ANNEXURE – 1: PLANT LAYOUT DIAGRAM

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QRA Report for Existing & New LPG Storage & Bottling Plant

of IOCL Visakhapatnam

ABBREVIATIONS

ALARP As Low As Reasonably Practicable

BLEVE Boiling Liquid Expanding Vapour Explosion

COMAH Control of Major Accident Hazards (UK)

DNV Det NorskeVeritas

EIV Emergency isolation valve

IOCL Indian Oil Corporation Limited

ISIR Individual-specific individual risk

kg Kilogramme

kW/m2 Kilowatt per square metre

LPG Liquefied Petroleum Gas

LSIR Location-specific individual risk

MoEF Ministry of Environment & Forests (Government of India)

MoP&NG Ministry of Petroleum & Natural Gas (Government of India)

MT Metric Tonne

OGP International Oil & Gas Producers Association

OISD Oil Industry Safety Directorate

psig Pounds per square inch gauge

QRA Quantitative Risk Assessment

ROV Remote operated valve

SH&E Safety, Health &Environment

UK-HSE United Kingdom – Health & safety Executive

VCE Vapour cloud explosion

QRA Report for Existing & New LPG Storage & Bottling Plant

of IOCL Visakhapatnam

1. INTRODUCTION

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 Indian Oil Corporation

Ltd. 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 89 Indane (LPG) bottling plants.

IOCL plan to expand the LPG storage capacity in their existing LPG Bottling Plant at Parawada

near Visakhapatnam in Andhra Pradesh State by installing additional three mounded LPG bullets

each with 600 MT capacity.

Being an organization with commitment to high standards of safety, health and environmental

protection, IOCL wish to ensure that all hazards and risks due to the existing and the proposed

additional mounded LPG storage in their LPG Bottling Plant at Visakhapatnam are properly

identified and necessary risk reduction measures are implemented.

Accordingly, IOCL have engaged the services of Vimta Labs Limited, Hyderabad to carry out a

Quantitative Risk Assessment (QRA) Study for the LPG storage in the LPG Bottling Plant

including the existing and new facilities at Visakhapatnam.

Vimta Labs Limited, accredited by QCI/NABET have carried out similar risk analysis studies for

a large number of LPG, LNG, oil & gas and chemical installations. This report presents the

QRA study for the existing and additional LPG Storage & Bottling Plant of IOCL

Visakhapatnam Facility.

QRA Report for Existing & New LPG Storage & Bottling Plant

of IOCL Visakhapatnam

Existing Mounded LPG

Bullets (3 x 600 MT)

Proposed Mounded LPG

Bullets (3 x 600 MT)

2. FACILITYDESCRIPTION

IOCL LPG Storage & Bottling Plant, Visakhapatnam

IOCL „Indane‟ LPG Bottling Plant at Parawada is located in Visakhapatnam district of Andhra Pradesh. The plant covering an area of 58.09 acres is situated in an industrial

area about 35 km south-west of Visakhapatnam. The site is well connected by road

through NH-16.

Map indicating location of the plant is shown in the Figure 2.1 below.

Figure 2.1: IOCL Visakhapatnam Site Location Map

The layout drawing of IOCL Visakhapatnam LPG Plant is enclosed in Annexure – 1.

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QRA Report for Existing & New LPG Storage & Bottling Plant

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Description of Facilities

IOCL LPG Bottling Plant at Visakhapatnam consists of the following systems:

Receipt of LPG by road tankers

Unloading LPG from tankers and transfer to storage tanks

Storage of LPG in mounded horizontal cylindrical pressure vessels(bullets).

Receiving of empty LPG cylinders

Filling of LPG into cylinders in carousel

Dispatch of filled cylinders

Filling of LPG in road tankers to other plants

Receipt of LPG by road tankers:

Tank Lorry Decantation/Filling Shed (TLD) with 8 bays has been provided to unload

LPG from road tankers and transfer to Storage Vessels.

LPG Storage

Details of the existing and proposed LPG storage vessels are provided in Table 2.1.

Table 2.1: Details of LPG Storage Vessels

S. No. Description Type Capacity (MT)

1 Existing LPG Storage Mounded bullets 3 x 600 = 1,800 MT

3 Proposed Additional

LPG Storage

Mounded bullets

3 x 600 = 1,800 MT

Total Storage Capacity Proposed 3,600 MT

The proposed additional storage will help to increase the coverage to 9 days.

The Storage vessels have been provided with all necessary fittings, for filling, emptying,

vapour pressurization, draining facilities and measuring devices like pressure gauges

temperature gauges, level indicators, high level alarm, safety relief valves etc.

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QRA Report for Existing & New LPG Storage & Bottling Plant

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Receipt of Empty LPG Cylinders

Four telescopic type unloading bays are provided for empty cylinders received in trucks.

All necessary inspections of the empty cylinders are carried out before going for filling.

The segregated cylinders are stacked separately and these are taken for testing/repair.

Filling of LPG in cylinders

Two electronic filling machines each with 24 points and cylinder conveyor have been

installed in filling shed for filling of 14.2 kg and 19 kg cylinders. Electronic check scales

are provided for checking weight of filled cylinders and weight correction unit machines,

Automatic valve testing machines, test bath for checking any leakage from cylinder bung

and body. The filling shed also contains hot air sealing machine for sealing of cylinders

prior to despatch and SQC machine for quality checks of cylinders. Processed cylinders

directly go to loading bays and the cylinders failing the test go are sent for repair.

Despatch of Filled Cylinders

After passing of all tests, the filled cylinders are loaded in trucks by using four telescopic

type loading bays.

LPG Pump and Compressor House

Three centrifugal pump have been installed to pump liquid LPG from storage vessels to

carousel. These pumps have been provided with pop-action valves on discharge lines and

are coupled to flame proof motors.

There are three LPG vapour compressors each coupled to a flame-proof motor for unloading of LPG tankers by differential pressure mechanism. The compressors have

maximum discharge pressure of 11.5 kg/cm2g. Details of LPG pumps and compressors are provided in Table2.2.

Table 2.2: Details of LPG Pumps & Compressors

Description Nos. Capacity

(M3/hr) Motor

(HP)

LPG Pump 1 85 60

LPG Pump 2 48 75

LPG Compressors 2 35 25

LPG Compressor 1 150 60

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QRA Report for Existing & New LPG Storage & Bottling Plant

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Fire Protection & Safety Measures

Storage and handling of LPG involves the following hazards:

Fire hazard due to ignition of leaking LPG liquid/vapour

Explosion due to delayed ignition of vapour cloud in flammable range formed by

large quantity of LPG mixed with air

Cold burn due to contact with flashing liquid LPG at very low temperature

Fire protection measures provided in the Visakhapatnam LPG installation include the

following:

Fire water system

Fire water storage tanks – 2 Nos. each 3700 KL (total 7400 KL)capacity

Fire water pumps with diesel engine drives - 5 Nos. each 410 M3/hr capacity

Fire water jockey pumps with motor drive - 2 Nos. each 20 M3/hr capacity

Fire water distribution network

Fire hydrants.

Monitors.

Water spray systems with deluge valves.

LPG received in road tankers is odorized with ethyl mercaptan to alert the people in the

area in case of any leaks.

Gas detectors are provided in areas around bullets, pumps & tanker loading stations.

Ignition sources are strictly controlled by the following measures:

Use of flame-proof electrical equipment &fittings

Strict implementation of „No Smoking‟rule

The LPG installation and fire protection measures conform to relevant OISD standards.

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QRA Report for Existing & New LPG Storage & Bottling Plant

of IOCL Visakhapatnam

3. SCOPE, OBJECTIVE & METHODOLOGY

3,1 Scope of work

The scope of work of this study covers the Quantitative Risk Assessment (QRA) for the

complete IOCL LPG Bottling Plant near Visakhapatnam in Andhra Pradesh state

including the existing and proposed additional mounded LPG storage vessels.

Objective of the Study

The objectives of this study are as follows:

Identifying the potential failure scenarios for release of flammable/ toxic

material in the LPG storage installation.

Carrying out consequence analysis for significant accident scenarios.

Carrying out for Quantitative Risk Analysis

Estimating the individual risk and societal risk due to the installation.

Assessing the risk with respect to the risk tolerance criteria

Identifying risk reduction measures wherever warranted to ensure that the risk is as low as reasonably practicable.

Methodology

Risk arises from hazards. Risk is defined as the product of severity of consequence and

likelihood of occurrence. Risk may be to people, environment, assets or business

reputation. This study is specifically concerned with risk of serious injury or fatality to

people. The flow diagram of QRA is shown in Figure 2.1.

The following steps are involved in quantitative risk assessment (QRA):

Study of the plant facilities and systems.

Identification of the hazards.

Enumeration of the failure scenarios.

Estimation of the consequences for the selected failure incidents.

Risk analysis taking into account the failure frequency, extent of consequences and exposure of people to the hazards.

Risk assessment to compare the calculated risk with risk tolerability criteria and

review the risk management system to ensure that the risk is “As Low As Reasonably Practicable”(ALARP)

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QRA Report for Existing & New LPG Storage & Bottling Plant

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Figure 3.1: Flow diagram of quantitative risk assessment (QRA)

Consequence Analysis

Consequence analysis for the selected failure scenarios is carried out using DNV Phast

software. Consequence analysis provides results for the following:

Dispersion of toxic clouds to defined concentrations

Heat radiation intensity due to jet fire and pool fire

Explosion overpressure

The renowned DNV Phast software package is used worldwide for consequence

modelling and quantitative risk analysis.

Phast is based on Unified Dispersion Modelling to calculate the results of the release of

material into the atmosphere. It can model both heavy gas dispersion and buoyant

dispersion of lighter-than-air gases. Phast has extensive material database and provides

for definition of mixtures.

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QRA Report for Existing & New LPG Storage & Bottling Plant

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Quantitative Risk Analysis(QRA)

The quantitative risk analysis is carried out using the renowned software

package PHAST Risk Micro (also known as SAFETI Micro) version 6.6

developed and marketed by Det Norske Veritas (DNV) of Norway.

The following input data are required for the risk calculation:

Process data for release scenarios (material, inventory, pressure,

temperature, type of release, leak size, location, etc.)

Estimated frequency of each failure case

Distribution of people in the plant/ adjoining area during the day

and night time.

Distribution of wind speed and direction (wind rose data).

Ignition sources

Failure Frequency Estimation

For objective and comprehensive risk analysis, whole range of leak sizes is

considered in each section containing large inventory of hazardous material

Small leak (5 mm diameter)

Medium leak (25 mm diameter)

Large leak (100 mm diameter)

Full bore leak.

Theoretically, Fault Tree Analysis (FTA) can be used for estimation of

failure rates for loss of containment from equipment. Fault tree is

constructed to show how the Top Event (loss of containment) can develop

from basic failure events through intermediate events connected by logic

gates. The two most widely used logic gates are „OR‟ gate and „AND‟ gate.

In the case of „OR‟ logic gate, any one of the input events will lead to the output event.

In the case of „AND‟ logic gate with two input events, the output event

will occur only when both the input events occur.

Following are the symbols used for fault tree analysis:

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QRA Report for Existing & New LPG Storage & Bottling Plant

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Figure 1.2: Symbols used in Fault Tree

Fault Trees for the hydrocarbon leakage scenario covering leak in Storage Tank, Pipelines and

Tank Lorry Decantation Shed are shown in figures below:

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QRA Report for Existing & New LPG Storage & Bottling Plant

of IOCL Visakhapatnam

Figure 3.3: Fault Tree for Hydrocarbon leak in Pipelines

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QRA Report for Existing & New LPG Storage & Bottling Plant

of IOCL Visakhapatnam

Figure 3.4: Fault Tree for Hydrocarbon leak in Storage Tank

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QRA Report for Existing & New LPG Storage & Bottling Plant

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Figure 3.5: Fault Tree for LPG Release in Tank Lorry Decantation Shed Area

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QRA Report for Existing & New LPG Storage & Bottling Plant

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In theory, fault tree analysis can be used to calculate the probability of the top event

based on the probabilities of all the basic events.

In the case of „OR‟ gate, the probability of occurrence of the output event is approximately the sum of the probabilities of occurrence of the input events.

Poutput Pinput1 + Pinput2

In the case of „AND‟ gate, the probability of occurrence of the output event is approximately the product of the probabilities of occurrence of the input events.

Poutput Pinput1 * Pinput2

In actual practice, calculation of failure rates using fault tree analysis is limited by non-

availability of failure rate data for many basic and external events involved.

The current practice in QRA is to estimate the failure rates required for failure scenarios

for different types of equipment using the historical failure frequency database published

by organizations such as International Oil & Gas Producers Association (OGP).

OGP Report No. 434-1 “Process Release Frequencies” for equipment &piping

OGP Report No. 434-3 “Storage Incident Frequencies”

Extract of generic failure rates for equipment items relevant to this study from OGP

database publication is shown in Table 3.1.

Table 3.1: Generic Failure Rate Data for Equipment Items

Equipment Item Leak size

5 mm 25 mm 100 mm

2" Pipe 1.80E-05 7.00E-06 0

6" Pipe 8.50E-06 2.70E-06 6.00E-07

2" Flange 7.60E-06 4.00E-06 0

6" Flange 1.10E-05 3.00E-06 2.00E-06

2" Valve (Manual) 7.70E-06 4.90E-06 0

6" Valve (Manual) 1.20E-05 4.70E-06 2.40E-06

2" Valve (Actuated) 7.30E-05 3.00E-05 0

6" Valve (Actuated) 6.60E-05 1.90E-05 8.60E-06

Instrument Connection 6.80E-05 2.50E-05 0

Pressure Vessel 2.00E-04 1.00E-04 5.10E-05

Centrifugal Pump 1.00E-03 2.90E-04 5.40E-05

Reciprocating Pump 1.20E-03 7.40E-04 5.00E-04

Reciprocating Compressor 8.00E-03 2.60E-03 8.80E-04

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Note:

Failure rate notation: 1.0E-05 per year means 1.0 x 10-5 per year

The results of quantitative risk analysis are commonly represented by the following

parameters:

Individual Risk

Societal Risk

Individual risk is the risk that an individual remaining at a particular spot would face

from the plant facility. The calculation of individual risk at a geographical location in

and around a plant assumes that the contributions of all incident outcome cases are

additive. Thus, the total individual risk at each point is equal to the sum of the individual

risks, at that point, of all incident outcome cases associated with theplant.

The individual risk value is a frequency of fatality, usually chances per million per year,

and it is displayed as a two-dimensional plot over a locality plan as contours of equal risk

in the form of iso-risk contours as shown in the following Figure 3.3.

Figure 3.6: Iso-Risk Contours on Site Plan (Typical)

Risk tolerability criteria

For the purpose of effective risk assessment, it is necessary to have established criteria

for tolerable risk. The risk tolerability criteria defined by UK Health & Safety Executive

(UK-HSE) are normally used for risk assessment in the absence of specific guidelines by

Indian authorities.

UK-HSE has, in the publications “Reducing Risk and Protecting People” and “Guidance

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QRA Report for Existing & New LPG Storage & Bottling Plant

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on ALARP decisions in control of major accident hazards (COMAH)” enunciated the tolerability criteria for individual risk.

The guidance on QRA also can be taken from MoEF, Gov. of India from their

publication “Technical EIA Guidance Manual for Offshore and Onshore Oil and Gas

Exploration Development and Production, September 2009.” and Bureau of Indian Standards Hazard Identification and Risk Analysis (IS15656:2006).

An individual risk of death of one in a million (1 x 10-6) per annum for both

workers and the public corresponds to a very low level of risk and should be

used as a guideline for the boundary between the risk acceptable and ALARP

regions.

An individual risk of death of one in a thousand (1 x 10-3) per annum should

on its own represent the dividing line between what could be just tolerable for any substantial category of workers for any large part of a working life, and

what is unacceptable. For members of the public who have a risk imposed on them „in the wider interest of society‟ this limit is judged to be an order of magnitude lower, at 1 in 10,000 (1 x 10-4) per annum.

The upper limit of tolerable risk to public, 1 x 10-4 per year is in the range of risk due to

transport accidents. The upper limit of acceptable risk, 1 x 10-6 per year, is in the range of risk due to natural hazard such as lightning.

The tolerability criteria for individual risk are shown in Figure 3.4.

Figure 3.7: Individual Risk Criteria

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QRA Report for Existing & New LPG Storage & Bottling Plant

of IOCL Visakhapatnam

Societal Risk (or Group Risk) Criteria

Societal Risk parameter considers the number of people who might be affected by

hazardous incidents. Societal risk is represented as an F-N (frequency-number) curve,

which is a logarithmic plot of cumulative frequency (F) at which events with N or more

fatalities may occur, against N.

Societal risk criteria indicate reduced tolerance to events involving multiple fatalities. For

example a hazard may have an acceptable level of risk for one fatality, but may be at an

unacceptable level for 10 fatalities. The tolerability criteria for societal risk as defined by

UK-HSE are shown in the following Figure 3.5 below.

Figure 3.8: Societal Risk Criteria

Risk Assessment

Based on the results of QRA, necessary measures to reduce the risk to ALARP are to be

formulated. For this purpose DNV Phast/ Safeti software provides the information

regarding risk contribution from each leak scenario modelled.

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QRA Report for Existing & New LPG Storage & Bottling Plant

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4. QUANTITATIVE RISKANALYSIS

Input Data for QRA

The failure scenarios and the relevant input data for QRA of existing and new LPG storage

and bottling plant of IOCL at Visakhapatnam are shown in Table 4.1.

Table 4.1: Failure scenarios and the relevant input data

S.No.

Description Material &

Phase

Temp.

(C)

Pressure

(kg/cm2g)

Leak Size

(mm)

Leak

Frequency (peryear)

Mounded LPG Bullets (Existing & Proposed New)

1 LPG Mounded Bullet

Liquid Inlet Line

LPG Liquid 30 7 5 3.0E-04

25 8.0E-05

100 3.0E-05

2 LPG Mounded Bullet

Liquid Outlet Line

LPG Liquid 30 7 + Liq.

Head

5 3.0E-04

25 1.0E-04

100 3.0E-05

3 LPG Mounded Bullet

Vapour Line

LPG Vapour 30 7 5 5.0E-04

25 2.0E-04

100 4.0E-05 LPG Transfer Pumps

4 LPG Transfer Pump LPG Liquid 30 10 5 7.5E-04

25 2.5E-04

100 4.0E-05 LPG Compressor

5 LPG Compressor LPG Vapour 60 11 5 3.0E-03

25 1.0E-03

100 9.0E-04 LPG Road Tanker & Unloading Arm

6 LPG Tanker &

Unloading Arm

LPG Liquid 30 7 5 5.0E-05

25 1.5E-05 LPG Cylinder Filling Carousel

7 LPG Cylinder Filling Line

LPG Liquid 30 10 5 3.0E-04

10 2.0E-05

Note: Failure rate 1.0E-05 per year means 1.0 x 10-5

peryear

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QRA Report for Existing & New LPG Storage & Bottling Plant

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Population Data

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

The distribution of personnel in the IOCL Visakhapatnam LPG storage and bottling

plant is shown in Table 4.2.

Table 4.2: Distribution of People in LPG Bottling Plant, Visakhapatnam

S.No

Responsibility

1st shift

2nd shift

3rd shift General shift

Total

1 Employees 15 15 3 10 43

2 Contract workers 30 30 2 10 72

3 Security 5 5 5 2 17 Total shift wise 50 50 10 22 132

Population of 10,000 is considered within 1 km around the LPG plant.

Ignition Sources

In case of gas leakage, ignition of the gas will result in damage due to fire or

explosion. Therefore, identification of ignition sources is important in risk analysis.

The electrical and instrument items in the installation conform to the electrical

hazardous area classification. Flame-proof electrical items will be installed in the

classified areas, and these will not be ignition sources. Vehicles inside the plant are

provided with spark arrestors in the exhaust.

There is no overhead HT electrical line in the plant area which may act as ignition

source.

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.

Transformer

MCC/ Electrical Room

DG set

Canteen

Vehicles on external roads

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Weather parameters

Weather parameters play a significant role in dispersion analysis. The notable

parameters for assessing the atmosphere are wind speed, atmospheric stability,

ambient temperature, humidity and topographic parameters.

Atmospheric stability represents the vertical turbulence in the air due to temperature

differentials caused by heating of the earth by solar radiation. Atmospheric stability

effects are represented through Pasquill parameters as follows shown in Table 4.3.

Table 4.3: Pasquill parameters

Stability Class Atmospheric Condition

A

B

C

D

E F

Very Unstable

Unstable

Slightly Unstable

Neutral

Stable

Very Stable

The relationship between wind speed and atmospheric stability is shown in

Table 4.4.

Table 4.4: Relationship between wind speed and atmospheric stability

Wind speed

Day-Time: Solar Radiation

Night-Time Cloud Cover

(m/s) Strong Medium Slight Thin <3/8

Medium >3/8

Overcast >4/5

<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

Category D (neutral) is the most probable at sites in moderate climates and may occur

for up to 80 % of the time at relevant sites. Stability F (very stable) represents the

most adverse condition in which dispersion extends over longer distances

horizontally. Normally, stability F occurs for short periods in the year, mainly during

winternights.

Weather data (monthly average maximum & minimum temperature and rain fall) for

Vijayawada are indicated in Table 4.5.

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Table 4.5: Weather Data for Visakhapatnam

Month Temperature (oC) Relative Humidity (%)

Rainfall

(mm) Max Min 08:30 17:30

January 31.6 14.4 76 65 7.4

February 34.3 16.8 75 65 13.8

March 37.3 19.5 71 66 6.6

April 37.8 22.2 68 70 24.2

May 40.1 23.1 68 69 45.3

June 40.4 23.9 72 69 117.7

July 37.0 23.7 78 73 128.2

August 36.2 23.8 78 74 161.4

September 35.5 23.3 79 77 171.9

October 34.6 21.5 75 73 194.7

November 32.7 17.5 69 68 73.5

December 31.1 14.8 69 64 6.0

Total 950.7

Wind rose diagram for distribution of wind direction and wind speed is shown in

Figure 4.1.

Figure 4.1: Wind Rose Diagram for Visakhapatnam

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The representative combinations of weather parameters for the site considered in this

study are shown in Table 4.6.

Table 4.6: Weather Parameters for Risk Analysis

Description #1 #2

Temperature (C) 35 20

Wind speed (m/s) 5 3

Atmospheric Stability D D

Hazardous Properties of LPG

The flammable consequences of LPG release from equipment are mainly the

following:

Jet fire/ pool fire/ flash fire

Vapour cloud explosion

Properties of LPG relevant to this QRA study are as follows.

Composition: Mixture of Propane and Butane

Normal Boiling Point: (-)6 C Lower Flammable Limit(LFL): 1.8 % (vol)

Upper Flammable Limit(UFL): 9.5 %(vol)

Auto ignition temperature: 410-580 C (approx.)

LPG is stored as liquid under pressure. LPG vapours are heavier than air and

disperse close to ground level. LPG odorized with Ethyl Mercaptan is received in

the plant so as to provide warning in case of leakage.

Consequence Analysis

Jet/ Pool Fire Radiation

The effect from jet fire and pool fire is thermal radiation intensity on the receptor

surface as shown in Table 4.7.

Table 4.7: Damage Effects due to Jet/ Pool Fire Radiation

Heat

Radiation

Intensity

(kW/m2)

Observed Effect

4 Sufficient to cause pain to personnel if unable to reach cover

within 20 seconds; however blistering of the skin (second- degree burn) is likely; 0% lethality.

12.5 Minimum energy required for piloted ignition of wood, melting of plastic tubing.

37.5 Sufficient to cause damage to process equipment.

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Thermal radiation intensity exceeding 37.5 kW/m² may cause escalation due to

damage of other equipment.

Thermal radiation intensity exceeding 12.5 kW/m² may cause ignition of

combustibles on buildings and impairment of escape route.

Thermal radiation intensity exceeding 4 kW/m² may cause burn injury on personnel

injury.

Vapour cloud explosion (VCE)

When a large quantity of flammable vapour or gas is released, mixes with air to

produce sufficient mass in the flammable range and is then ignited, the result is a

vapour cloud explosion (VCE). In the LPG installation large release of LPG from

equipment or piping has potential for vapour cloud explosion. The damage effect of

vapour cloud explosion is due to overpressure as shown in Table 4.8.

Table 4.8: VCE over pressure limit and Observed Effect

Over-pressure Effect Observed Damage bar(g) psig

0.021 0.3 “Safe distance” (probability 0.95 of no serious damage below this value); projectile limit; some damage to

house ceilings; 10% of window glass broken.

0.069 1 Repairable damage; partial demolition of houses; steel

frame of clad building slightly distorted.

0.138 2 Partial collapse of walls of houses.

0.207 3 Heavy machines in industrial buildings suffered little

damage; steel frame building distorted and pulled away

from foundations.

Consequence Analysis Results for Maximum Credible Scenarios

The whole range of leak sizes (small, medium & large) with the appropriate failure

frequencies are taken into account for QRA using DNV Phast/ Safeti software.

Consequence analysis modelling for all the scenarios is carried out by Phast which is a

part of Safeti software. Results of the consequence analysis is further processed

internally by Safeti software to derive the results for QRA.

It is necessary to display the results of consequence analysis for selected cases

representing maximum credible scenarios.

In the case of equipment and associated piping, sources of release of hazardous

materials normally encountered are the following:

Seal leak in pumps and valves

Leaks from tanker unloading arms

Leaks from corrosion damage

Leaks from flange joints

Leaks from damaged small-bore connections for instruments, drains &vents.

Pumps used in LPG plants are normally provided with advanced type of mechanical

seals. Any leak from such seals will be from a small clearance around the shaft. The

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leak size is conservatively estimated as equivalent to 5 mm diameter hole with cross

sectional area of about 20 sq. mm.

In the case of LPG tanker unloading arms, leaks from articulated joints or coupling

are estimated to be equivalent to 5 mm diameter hole. In order to prevent release of

LPG in case of damage of the unloading arm by accidental movement of tanker the

following safety features are provided:

Break-away coupling

Excess flow check valve (EFCV) installed inside the tanker.

Corrosion damage in equipment or piping usually starts as small pinhole leak or

crack. The leak size is estimated as equivalent to 5 mm diameter hole. If the leak is

allowed to continue it will become larger in size.

Flange joints in LPG plant equipment and piping are normally raised face or ring type

(RTJ). The raised face flanges are provided with spiral wound metallic gaskets which

are not expected to rupture catastrophically. Leak from such flange joint will be from

small gap due to the following causes:

Excess strain due to thermal expansion or improper supports

Weakening of one or more bolts in the flange joint

The flow area for leakage from flange joint will be the length of opening along inner

circumference multiplied by the gap. For 8” (200 mm) size pipe, flow area covering

25% of flange joint and 2 mm gap is 320 sq.mm. which is equivalent to 20 mm

diameter hole.

Small bore connections for instrument tapping are normally ¾ inch size. Vent and

drain connections are normally 1 inch (25 mm) size.

Taking into account all the above points, leak size equivalent to 25 mm diameter hole

is considered for represent, on a conservative basis, the maximum credible release

scenario in this facility.

Results of consequence analysis by Phast software for the maximum credible leak

scenarios relevant to IOCL Vizag LPG bottling plant are shown in the Table 4.9.

Graphical results plotted on the site map drawings are shown in Figure 4.2 to 4.17.

Table 4.9: Results of Consequence Analysis for LPG Bottling Plant (LPG

Bullet proposed as well as existing)

S.No.

Description

Parameter

Downwind Distance

(metres)

Downwind Distance (metres)

Weather (Wind speed &

Stability)

Weather (Wind speed &

Stability)

5 m/s; D 5 m/s; D 3 m/s; D 5 m/s; D

1

.

LPG Bullet Liquid Line Leak (Existing Bullet 600 MT) LPG Bullet (Proposed Bullet

600 MT) Liquid Line Leak

Pool Fire

Radiation 4 kW/m2 54 55 54 55

12.5 kW/m2 35 35 35 35

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Intensity 37.5 kW/m2 19 18 19 18

Flash Fire

Envelope

LFL (1.7%) 57 64 57 64

VCE

Overpressure

0.02 bar 172 226 172 226

0.07 bar 86 110 86 110

0.2 bar Not

reached

Not

reached Not reached Not reached

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Table 4.10: Results of Consequence Analysis for LPG Bottling Plant

S.No.

Description

Parameter

Downwind Distance (metres)

Weather (Wind speed & Stability)

5 m/s; D 3 m/s; D

2. LPG Pump Discharge Line Leak

Pool Fire Radiation Intensity 4 kW/m2 48 48

12.5 kW/m2 31 30

37.5 kW/m2 17 15

Flash Fire Envelope LFL (1.7%) 59 67

VCE Overpressure 0.02 bar 184 226

0.07 bar 90 109

0.2 bar Not reached Not reached

3. LPG Vapour Compressor Discharge Line Leak

Jet Fire Radiation Intensity 4 kW/m2 20 20

12.5 kW/m2 17 16

37.5 kW/m2 10 12

Flash Fire Envelope LFL (1.7%) 8 9

44

LPG Road Tanker Liquid Unloading Arm Leak

Pool Fire Radiation Intensity 4 kW/m2 26 26

12.5 kW/m2 17 17

37.5 kW/m2 8 7

Flash Fire Envelope LFL (1.7%) 31 33

VCE Overpressure 0.02 bar 98 102

0.07 bar 50 52

0.2 bar Not reached Not reached

5. LPG Cylinder Filling Carousel Line Leak

Pool Fire Radiation Intensity 4 kW/m2 8 8

12.5 kW/m2 5 5

37.5 kW/m2 2 2

Flash Fire Envelope LFL (1.7%) 13 14

VCE Overpressure 0.02 bar 33 36

0.07 bar 17 18

0.2 bar Not reached Not reached

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Note: After expansion, the existing facilities like pumps, compressors and carousel will be

used. So, the table 4.9 shows comparison of consequence analysis for release from bullet

liquid line (proposed as well as existing).

Legend for Consequence Analysis Graphs

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1(a). Existing Mounded LPG Bullet Liquid Line Leak

Figure 4.2: Existing Mounded Bullet Liquid Line Leak - Pool Fire Radiation Intensity

Figure 4.3: Existing Mounded Bullet Liquid Line Leak – Flash Fire Envelope

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1(a). Existing Mounded LPG Bullet Liquid Line Leak (continued)

Figure 4.4: Existing Mounded Bullet Liquid Line Leak – VCE Overpressure

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1(b) New Mounded LPG Bullet Liquid Line Leak

Figure 4.5: New Mounded LPG Bullet Liquid Line Leak - Pool Fire Radiation Intensity

Figure 4.6: New Mounded LPG Bullet Liquid Line Leak – Flash Fire Envelope

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1(b). New Mounded LPG Bullet Liquid Line Leak (continued)

Figure 4.7: New Mounded LPG Bullet Liquid Line Leak – VCE Overpressure

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2. LPG Pump Discharge Line Leak

Figure 4.8: LPG Pump Discharge Line Leak - Pool Fire Radiation Intensity

Figure 4.9: LPG Pump Discharge Line Leak – Flash Fire Envelope

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2. LPG Pump Discharge Line Leak (continued)

Figure 4.10: LPG Pump Discharge Line Leak – VCE Overpressure

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3. LPG Vapour Compressor Discharge Line Leak

Figure 4.11: LPG Compressor Discharge Line Leak – Jet Fire Radiation Intensity

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4. LPG Road Tanker Liquid Unloading Arm Leak

Figure 4.12: Road Tanker Liquid Arm Leak – Pool Fire Radiation Intensity

Figure 4.13: Road Tanker Liquid Arm Leak – Flash Fire Envelope

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4. LPG Road Tanker Liquid Unloading Arm Leak (continued)

Figure 4.14: Road Tanker Liquid Arm Leak – VCE Overpressure

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QRA Report for Existing & New LPG Storage & Bottling Plant

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5. LPG Cylinder Filling Carousel Leak

Figure 4.15: LPG Cylinder Filling Carousel Leak – Pool Fire Radiation Intensity

Figure 4.16: LPG Cylinder Filling Carousel Leak – Flash Fire Envelope

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QRA Report for Existing & New LPG Storage & Bottling Plant

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5. LPG Cylinder Filling Carousel Leak(continued)

o

Figure 4.17: LPG Cylinder Filling Carousel Leak – VCE Overpressure

Review of Consequence Analysis Results for LPG Storage & Bottling Plant

Based on the results of consequence analysis, the following observations are made:

In case of maximum credible scenario represented by 25 mm leak in liquid and

vapour lines connected to mounded LPG bullets, pumps and compressor, the

significant effect distances for pool/ jet fire radiation intensity and flash fire envelope

are contained within the plant boundary.

In case of vapour cloud explosion due to delayed ignition of the flammable cloud

formed by LPG leak from mounded bullet outlet line, 0.02 bar overpressure effect

may extend slightly outside the north boundary of the plant. However, this level of

overpressure effect will not cause any serious damage..

Mounded LPG bullets are not susceptible to catastrophic failure and BLEVE/ fire ball

hazard by prolonged exposure to external jet fire or pool fire.

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QRA Report for Existing & New LPG Storage & Bottling Plant

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QRA Results for LPG Storage & Handling

As seen in the previous section, consequence analysis for failure scenario involving

large release of LPG may result in different outcomes, namely pool fire, jet fire, flash

fire and vapour cloud explosion.

Event Tree describes the development of these outcomes depending on the prevailing

conditions such as immediate ignition, delayed ignition and congestion. A typical

Event Tree for release of LPG from storage tank is shown in Figure 4.18.

Figure 4.18: Event Tree for LPG Leak from Storage System

As the LPG storage vessel is mounded type, fireball/ BLEVE hazard is not

considered.

DNV SAFETI software calculates the individual risk and societal risk based on the

Event Tree, wind rose data for probability of wind in each direction, location of

ignition sources and population density in different areas.

The detailed results of QRA for IOCL LPG bottling plant in Visakhapatnam provided

as outputs from Phast Risk software are presented in this section.

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1 x 10-5 per year

1 x 10-6 per year

Individual risk

The iso-risk contours for the complete LPG bottling plant including the existing and

new mounded storage vessels are shown in Figure 4.19.

Figure 4.19: Iso-Risk Contours for Individual Risk

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QRA Report for Existing & New LPG Storage & Bottling Plant

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1 x 10-5 per year

1 x 10-6 per year

Enlarged diagram of iso-risk contours diagram is shown in Figure4.20.

Figure 4.20: Iso-Risk Contours (Enlarged Diagram)

Individual Risk to Public

Risk contour of 1 x 10-6 per year falls within the plant boundary.

Therefore the maximum individual risk to members of the public outside the plant

boundary is less than 1 x 10-6 per year which is on Acceptable level.

Individual Risk to Plant Personnel

The highest iso-risk contour inside the plant area is 1 x 10-5 per year. Therefore the

individual risk at any location in the plant does not exceed 1 x 10-4 per year. By taking risk transect at different locations, it is found that the maximum location-specific

individual risk (LSIR) in the plant area is 5 x 10-5 per year.

However, any individual person is present in the plant location only for a limited

period in a year. The individual-specific individual risk (ISIR) is calculated taking

into account the fraction of time the individual stays at the location. Normally the

plant personnel work in daily shift of 8hours. Therefore the maximum individual-

specific individual risk,

ISIR = LSIR x (8/24) per year.

= (5 x 10-5) x (1/3)per year = 1.7 x 10-5 per year

The maximum value of individual risk to plant personnel in the IOCL Visakhapatnam

LPG storage & bottling plant is 1.7 x 10-5 per year.

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Risk to

Personnel Risk to

Public

The values of maximum individual risk to public and plant personnel in IOCL

Visakhapatnam LPG storage & bottling plant in comparison with the risk tolerance

criteria are shown in Figure 4.21.

Intolerable

Risk

10-3 per year

10-4 per year

Max. Individual Risk toPersonnel:

1,7 x 10-5 peryear

10-6 per year

Risk Tolerable

if ALARP

Acceptable

Risk

Max. Individual Risk to Public:

1.0 x 10-6 per year

10-6 per year

Figure 4.21: Max. Individual Risk at IOCL Visakhapatnam LPG Plant

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Societal Risk

The FN Curves for societal risk due to existing & proposed new LPG storage &

bottling plant of IOCL at Visakhapatnam is shown in Figure 4.22.

Figure 4.22: Societal Risk due to IOCL Visakhapatnam LPG Plant,

It is seen that the societal risks due to existing and proposed new LPG mounded

storage & bottling plant of IOCL at Visakhapatnam is in the Acceptable (Negligible)

Risk region.

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5. CONCLUSIONS & RECOMMENDATIONS

Conclusions

The conclusions of QRA study for the IOCL Visakhapatnam LPG bottling plant

including the existing three mounded LPG storage vessels and the proposed additional

three mounded LPG storage vessels are as follows.

Individual risk to the public is 1.0E-06 per year which is in Acceptable level.

Maximum individual risk to personnel working in the LPG storage & bottling plant is 1.7E-05 per year, which is in the lower part of ALARP

region.

Societal risk due to LPG bottling plant is in Acceptable region.

Based on the above results it is concluded that the LPG storage & bottling plant of

IOCL at Visakhapatnam conform to the specified risk tolerance criteria.

In case of maximum credible scenario represented by 25 mm leak in liquid and

vapour lines connected to mounded LPG bullets, pumps and compressor, the

significant effect distances for pool/ jet fire radiation intensity and flash fire envelope

are contained within the plant boundary.

In case of vapour cloud explosion due to delayed ignition of the flammable cloud

formed by LPG leak from mounded bullet outlet line, 0.02 bar overpressure effect

may extend slightly outside the north boundary of the plant. However, this may cause

only light damage such as window glass breakage.

Mounded LPG bullets are not susceptible to catastrophic failure and BLEVE/ fire ball

hazard.

IOCL has responsibility to maintain the risk within the ALARP region by ensuring

effective safety management system and adopting the best industry practices

applicable to operation and maintenance of LPG storage and bottling plant.

The LPG storage & bottling plant of IOCL at Visakhapatnam conforms to the

requirements of OISD standards 144, 150 and 158.

It is significant to note that the existing three LPG bullets as well as the proposed

three additional bullets are mounded type which represents the industry best practice

with regard to safety.

Fire protection system has been provided conforming to the requirement of OISD

standards. This includes the following:

Fire/ gas detectors with alarms

Fire water storage and distribution system with hydrants monitors

Fixed water spray system for LPG storage, pumps, road tanker unloading,

cylinder filling and cylinder storage areas.

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Remote operated emergency isolation valves, non-return valves and excess flow

check valves have been provided as per the requirement of OISD standards.

Emergency response/ disaster management plan has been implemented for the

existing LPG storage and bottling plant. This will be updated for the proposed

additional LPG storage.

Recommendations

The following recommendations are made in order to ensure that the risks at IOCL

Visakhapatnam LPG storage & bottling plant are maintained at low level by control

and mitigation of the maximum credible accident scenarios.

1. Periodic preventive maintenance of pumps, compressors, valves, flanges,

nozzles, flame arrestors, breather valves, equipments at filling shed etc. must be

done.

2. 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.

3. Emergency push buttons to close the remote-operated isolation valves (EIVs)

and stop LPG pumps/ compressors are also to be provided in the plant area at

appropriate locations neat bullets, pumps and tanker loading bays.

4. Raised face flanges with metallic spiral wound gaskets or tongue & groove type

flanges should be used in LPG service.

5. Fire water system (hydrants, monitors and fixed water sprays) are to be

extended to cover the new mounded LPG bullets.

6. Gas detectors are to be provided near the openings for liquid and vapour lines

on top and bottom of LPG bullets, LPG pump house, tanker unloading bays and

cylinder filling areas.

7. Prevention of ignition

The flame-proof electrical equipment should be properly maintained by competent and trained personnel to ensure their integrity.

The spark arrestors used for vehicles should be maintained by regular checking.

Use of cell phones should not be allowed in the LPG installation.

8. 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. Safety manual and Public

awareness manual needs to be prepared and distributed to all employees and nearby

public.

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

plant.

10. 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

11. Ensure proper working of Security circuit containing fusible plugs to detect heat/fire

and thereby closing ROVs in case of fire.

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

operating condition.

13. Ensure selection of electrical/lighting equipment‟s based on HAC (hazardous area

classification).

14. In order to reduce the frequency of failures and consequent risk, codes, rules and

standards framed e.g. OISD 144/150, SMPV rules (Unfired), gas cylinder rules etc.

should be strictly followed with respect to construction of new facilities.

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

surface.

16. Ensure provision of a gas extraction system with suction points at critical places

where gas concentration is high like carousel, evacuation, valve change shed etc.

***************

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ANNEXURE – I

IOCL VISAKHAPATNAM LPG PLANT LAYOUT DRAWING