RAPID RISK ASSESSMENT STUDIES
FOR
BPCL IRUGUR INSTALLATION
IRUGUR, NEAR COIMBATORE, TAMILNADU
Submitted to:
Bharat Petroleum Corporation Limited
Prepared by:
Vimta Labs Ltd.
142 IDA, Phase-II, Cherlapally Hyderabad–500 051
[email protected], www.vimta.com (NABET & QCI Accredited, NABL Accredited and ISO 17025 Certified Laboratory,
Recognized by MoEF, New Delhi)
November, 2014
Bharat Petroleum Corporation Limited New Delhi
For and on behalf of VIMTA Labs Limited Approved by : M. Janardhan Signed : Position : Head & Vice President (Env) Date : November 05, 2014
This report has been prepared by Vimta Labs Limited with all reasonable
skill, care and diligence within the terms of the contract with the client,
incorporating our General Terms and Conditions of Business and taking
account of the resources devoted to it by agreement with the client.
PREFACE
RAPID RISK ASSESSMENT STUDIES
FOR BPCL IRUGUR INSTALLATION
IRUGUR, NEAR COIMBATORE, TAMILNADU
Rapid Risk Assessment Studies for BPCL Irugur Installation, near Coimbatore, Tamil Nadu
VIMTA Labs Limited, Hyderabad 1
Table of Contents
_______________________________________________________________
Chapter Title Page
_______________________________________________________________
Table of Contents 1
List of Figures 2
List of Tables 2
1.0 Introduction
1.1 Background 3
1.2 RRA Study 3
2.0 Facility Description
2.1 BPCL Terminal at Irugur 4
3.0 Scope, Objective & Methodology
3.1 Scope 6
3.2 Objective 6
3.3 Methodology 6
4.0 Rapid Risk Analysis
4.1 Input Data 12
4.2 Population Data 13
4.3 Ignition Sources 13
4.4 Weather Data 14
4.5 Consequence Analysis Results 17
4.6 RRA Results 29
5.0 Conclusions & Recommendations
5.1 Conclusions 34
5.2 Recommendations 34
Annexure-I Irugur Top Installation – Layout Plan showing Facilities
Rapid Risk Assessment Studies for BPCL Irugur Installation, near Coimbatore, Tamil Nadu
VIMTA Labs Limited, Hyderabad 2
List of Figures
_______________________________________________________________
Figure Title Page
_______________________________________________________________ 3.1 Flow Diagram of Rapid Risk Assessment (RRA) 7 3.2 ISO-Risk Contours on Site Plan (Typical) 9 3.3 Individual Risk Criteria 10 3.4 Societal Risk Criteria 11 4.1 Wind rose Diagrams 15 4.2 Dyke Fire – MS Tank (T-20) Pool Fire Radiation Intensity 20 4.3 MS Tank (T-20) – Vapour Cloud Explosion Overpressure 21 4.4 Dyke Fire – New HSD Tank (T-21) Pool Fire Radiation Intensity 22 4.5 Dyke Fire – New HSD Tank (T-23) Pool fire Radiation Intensity 23 4.6 Dyke Fire – Existing HSD Tank (T-1) Pool Fire Radiation Intensity 24 4.7 Dyke Fire – Existing HSD Tank (T-3) Pool Fire Radiation Intensity 25 4.8 Dyke Fire – Existing HSD Tank (T-7) Pool Fire Radiation Intensity 26 4.9 Pipeline Pump Discharge Leak (25 mm) Pool fire Radiation Intensity 27 4.10 Pipeline Pump Discharge Leak (25 mm) VCE Overpressure 28 4.11 ISO- Risk Contours for Individual Risk at BPCL Irugur Terminal 29 4.12 ISO- Risk Contours for Individual Risk at BPCL Irugur-Terminal 30 4.13 Individual Risk at BPCL Irugur Terminal 32 4.14 Societal Risk at BPCL Irugur Terminal 33
List of Tables
Tables Title Page
2.1 Details of Storage Tanks at BPCL Irugur Terminal 4
4.1 Failure Scenarios and the Relevant Input Data 12
4.2 Population Data – BPCL Irugur Terminal 13
4.3 Climatological Data – Coimbatore 14
4.4 Definition of Pasquill Stability Classes 16
4.5 Weather Parameter for Risk Analysis 17
4.6 Effects of Heat Radiation 17
4.7 Effects of Overpressure 18
4.8 Consequence Analysis Results 19
Rapid Risk Assessment Studies for BPCL Irugur Installation, Coimbatore, Tamil Nadu
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1.0 INTRODUCTION
1.1 Background
Bharat Petroleum Corporation Limited (BPCL) operate a large POL terminal at
Irugur near Coimbatore in Tamil Nadu. Expansion of facilities at Irugur Terminal
is planned to handle the requirement for evacuation of white oil products after
capacity expansion of Kochi Refinery and commissioning of Irugur – Bengaluru
Pipeline.
1.2 Rapid Risk Assessment Study
BPCL being an organization with commitment to high standards of process safety
management wish to identify the hazards associated with the expanded facilities
at Irugur Terminal and implement all necessary measures to ensure that the risk
due to the pipeline are kept as low as reasonably practicable. With this objective,
BPCL have engaged the services of Vimta Labs, Hyderabad, for carrying out a
Rapid Risk Assessment (RRA) study for the Irugur installation.
Vimta Labs have wide experience in conducting environmental impact assessment
(EIA) study and risk analysis for a large number of oil & gas facilities, petroleum
installations, chemical/ fertilizer plants, power plants, mines & mineral
installations etc.
The Rapid risk assessment (RRA) report for the BPCL Irugur Terminal near
Coimbatore was submitted in December 2013. This RRA report is now updated for
provision of rail tank wagon loading gantry.
Rapid Risk Assessment Studies for BPCL Irugur Installation, Coimbatore, Tamil Nadu
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2.0 FACILITY DESCRIPTION
2.1 BPCL Terminal at Iruguru
The details of storage and pumping facilities at Irugur Terminal of BPCL near
Coimbatore are shown below in Table 2.1.
TABLE-2.1
DETAILS OF STORAGE TANKS AT BPCL IRUGUR TERMINAL
Tank No.
Product Tank diameter
(m)
Tank height/ length (m)
Class Tank type Tank Capacity
New Tanks (Above-Ground Type)
T-20 MS 40.00 15.00 A Floating roof 17,117 KL
T-21 HSD 38.00 18.00 B Cone roof 20,000 KL
T-22 HSD 38.00 18.00 B Cone roof 20,000 KL
T-23 HSD 38.00 18.00 B Cone roof 20,000 KL
FW-3 Fire water 20.00 12.00 - Cone roof 3,770 KL
FW-4 Fire water 20.00 12.00 - Cone roof 3,770 KL
Existing Tanks (Above-Ground Type)
T-1 MS 30.00 15.00 A Floating roof 9,597 KL
T-2 MS 30.00 15.00 A Floating roof 9,594 KL
T-3 HSD 30.00 15.00 B Floating roof 9,585 KL
T-4 SKO 24.00 15.00 B Floating roof 6,128 KL
T-5 SKO 24.00 15.00 B Floating roof 6,131 KL
T-6 HSD 36.57 15.00 B Floating roof 14,298 KL
T-7 HSD/ MS 40.00 15.00 B Floating roof 17,157 KL
T-8 MS 40.00 15.00 A Floating roof 17,117 KL
T-9 LPPHSD/ SKO 24.00 15.00 B Floating roof 6,130 KL
T-10 LPPHSD 24.00 15.00 B Floating roof 6,128 KL
T-12 Slop 13.00 9.00 A Cone roof 1,201 KL
T-13 Slop 13.00 9.00 A Cone roof 1,204 KL
T-14 Ethanol 3.20 13.20 A Horizontal 100 KL
T-15 Ethanol 2.75 13.00 A Horizontal 70 KL
FW-1 Fire water 17.00 12.00 - Cone roof 2,732 KL
FW-2 Fire water 17.00 12.00 - Cone roof 2,732 KL
Existing Tanks (Under-Ground Type)
T-11 Slop 2.00 5.00 A Horizontal 15 KL
T-16 MS (Speed) 3.20 13.20 A Horizontal 100 KL
T-17 HSD (Speed) 3.20 13.20 B Horizontal 100 KL
T-18 MS (Speed
97) 2.75 8.00 A Horizontal 45 KL
T-19 HSD (Speed) 2.012 6.75 A Horizontal 20 KL
The layout drawing titled for BPCL Irugur Terminal is attached at Annexure-1.
Irugur Top Installation – Layout Plan Showing Facilities (BPCL
Drawing No. IRG-001)
BPCL Irugur terminal has been made fully automated terminal with entry and exit
control, integrated tank farm management system, automated truck tanker
loading facility, automated fire alarm/ fighting facility and network communication
system.
Rapid Risk Assessment Studies for BPCL Irugur Installation, near Coimbatore, Tamil Nadu
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It is proposed to provide a railway gantry for loading of tank Wagons for
transporting products from Irugur to various locations. Broad details are as
follows.
Products to be handled: MS (Euro 3 & Euro 4 ), HSD (Euro 3 & Euro 4), SKO
and ATF (future)
The gantry will be about 700 m long located parallel to north compound wall.
No of Wagons to be filled simultaneously: One full rake of 50 wagons of
approx. capacity 58-68 KL each
Filling in tank wagons will be through loading arms and flow meters with
automation provided for monitoring and control.
Fire protection facilities have been provided fully meeting the requirements of Oil
Industry Safety Directorate Standard (OISD-117). These include the following:
Fire water storage tanks
Main fire water pumps and jockey pumps
Fire water network with hydrants, monitors and medium-velocity sprinkler
systems
Fixed foam system
Mobile fire fighting equipment
Portable fire extinguishers
Fire detection & alarm system including manual call points
Medium velocity spray will be provided for full length of gantry as per
OISD/MBLR for fire fighting. Network of water hydrant/ monitor at 30 m
spacing will also be provided all around the gantry.
Fire and gas detectors are provided in the pipeline pump house with safety
interlock to shut down the pumps in case of hydrocarbon leak.
An Emergency Management System has been provided in total operation
management and in emergency, on operating ESD switch, all operation in the
terminal will stop the pumps and close the motor operated valves at the tank
outlets.
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3.0 SCOPE OBJECTIVE & METHODOLOGY
3.1 Scope
The scope of this RRA study covers the complete Irugur installation of BPCL
including the existing facilities and the proposed additional facilities for storage
tanks and pumping systems to handle the movement of white oil products by
Irugur – Bengaluru Pipeline.
3.2 Objective
The objectives of this study are as follows:
Identify major accident scenarios associated with the storage and handling of
hydrocarbons in the installation,
Carry out consequence analysis for the significant accident scenarios
Carry out Rapid Risk Assessment (RRA), and
Identify measures for risk reduction wherever warranted.
3.3 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 following steps are involved in Rapid Risk Assessment (RRA):
Study of the plant facilities and systems.
Identification of the hazards.
Enumeration of the failure incidents.
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 level with risk tolerability
criteria and review of the risk management system to ensure that the risk is
“As Low As Reasonably Practicable” (ALARP)
The process of Rapid Risk Assessment (RRA) is shown in the following block
diagram in Figure-3.1.
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FIGURE-3.1
FLOW DIAGRAM OF RAPID RISK ASSESSMENT (RRA)
3.3.1 Consequence Analysis
Consequence analysis for the selected failure scenarios is carried out using DNV
Phast software which provides results for selected failure scenarios such as the
following:
Dispersion of toxic clouds to defined concentrations
Heat radiation intensity due to pool fire and jet fire
Explosion overpressure
Phast stands for ‘Process Hazard Analysis Software Tool’. It uses Unified
Dispersion Modeling (UDM) to calculate the results of the release of material into
the atmosphere.
Phast has extensive material database and provides for definition of mixtures.
Phast software is well validated and extensively used internationally for
consequence and risk analysis.
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3.3.2 Rapid Risk Analysis (RRA)
The Rapid Risk Analysis is carried out using the renowned DNV software Phast
Risk Micro (previously known as SAFETI Micro) version 6.6.
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 wind speed and direction (wind rose data).
Distribution of personnel/ population in the plant/ adjoining area during the
day and night time.
Ignition sources
Failure frequencies are estimated using generic failure databases 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”
For objective and comprehensive risk analysis, 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.
In case of storage tanks, dyke fire is also considered.
The results of RRA 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 the plant.
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 Figure 3.2.
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FIGURE-3.2
ISO-RISK CONTOURS ON SITE PLAN (TYPICAL)
3.3.3 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 on ALARP decisions in control of major accident hazards (COMAH)”
enunciated the tolerability criteria for individual risk .
Indian Standard IS 15656:2006 provides guidelines for hazard identification and
risk analysis.
The risk tolerability criteria are as follows:
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 broadly acceptable and
tolerable 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.
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Intolerable Risk
Risk Tolerable If ALARP
Broadly Acceptable
10-3
per year
10-6
per year
10-4
per year
10-6
per year
Risk to Personnel
Risk to Public
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 broadly 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-3.3.
FIGURE-3.3
INDIVIDUAL RISK CRITERIA
3.3.4 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
3.4.
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FIGURE-3.4
SOCIETAL RISK CRITERIA
3.3.5 Risk Assessment
Based on the results of RRA, necessary measures to reduce the risk to ALARP are
to be formulated. For this purpose the information regarding top risk contributors
provided by Phast Risk software is useful.
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4.0 RAPID RISK ANALYSIS
4.1 Input Data
The failure scenarios and the relevant input data for RRA of BPCL Irugur Terminal
are tabulated below in Table 4.1.
TABLE 4.1
FAILURE SCENARIOS AND THE RELEVANT INPUT DATA
Item Description Failure Scenario Failure Rate for Each Item
New Storage Tanks Dyke fire
Surface fire
6.0E-05 per year
9.0E-05 per year MS Tank (T-20)
HSD Tanks (T-21/22/23)
Existing Storage Tanks
Dyke fire
Surface fire
6.0E-05 per year
1.2E-04 per year
MS/ Slop (T-1/2/7/8/12/13)
HSD/SKO (T-3/4/5/6/9/10)
Ethanol/MTO (T-14/15)
Product Pumps
5 mm leak
25 mm leak
100 mm leak
2.1E-03 per year
3.8E-04 per year
6.8E-05 per year
Truck Tanker Loading Gantry
5 mm leak
25 mm leak
100 mm leak
1.3E-03 per year
1.2E-04 per year
2.9E-05 per year
Rail Tank Wagon Loading Gantry
5 mm leak
25 mm leak
100 mm leak
1.3E-03 per year
1.2E-04 per year
2.9E-05 per year
Pipeline Pumps
5 mm leak
25 mm leak
100 mm leak
2.1E-03 per year
3.8E-04 per year
6.8E-05 per year
Notes:
Inventories are based on the data shown in Table 3.1
Failure rate notation: 6.0E-05 per year means 6.0 x 10-5 per year
Considering fully manned operations in the Terminal and provision of
fire & gas detection system with safety shut down interlock, release
duration for leaks in pump house/ gantry is estimated as 1 minute.
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4.2 Population Data
The distribution of personnel in BPCL Irugur Terminal is shown in Table 4.2.
TABLE 4.2
POPULATION DATA – BPCL IRUGUR TERMINAL
S. No Area Number of Persons
1 Control room 2
2 Loading area 18
3 Pump house 2
4 Tank farms 3
5 Security 5
6 Admin building 20
7 Parking area 10
4.3 Ignition Sources
Flammable liquid hydrocarbons (MS, HSD, SKO etc.) are stored and handles in
the Devangonthi Terminal. In case of leakage or spillage, ignition of the
hydrocarbon 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 will 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.
Road tanker vehicles entering the depot will be provided with spark arrestors for
engine exhaust.
The following ignition sources are identified for input to Phast Risk software.
MCC room, transformer yard DG room etc. which are in unclassified area
The main road adjacent to the Depot.
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4.4 Weather Data
The weather data for the site required for dispersion analysis and RRA are
provided in Table-4.3.
TABLE-4.3
CLIMATOLOGICAL DATA- COIMBATORE
Month Atmospheric
Pressure (hPa)
Temperature
(0C)
Relative
Humidity (%)
Rainfall
(mm)
0830 Hrs
1730 Hrs
Max. Min. 0830 Hrs
1730 Hrs
Monthly Total
January 999.5 995.6 32.2 19.9 76 51 10.4
February 998.6 994.2 35.0 20.7 75 42 5.3
March 997.4 992.7 37.5 22.5 73 38 13.3
April 995.3 990.7 38.9 24.9 71 46 44.3
May 992.6 988.8 39.9 25.9 63 48 55.1
June 992.3 989.0 39.0 25.8 59 48 48.5
July 992.4 989.3 38.0 25.5 60 51 57.6
August 992.9 989.4 37.8 25.1 62 52 85.5
September 994.0 990.1 36.9 24.3 66 55 108.8
October 995.8 992.1 35.5 23.4 76 65 189.9
November 997.3 993.8 32.8 22.4 79 69 153.1
December 998.7 995.2 31.5 21.0 78 64 63.5
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Wind rose diagrams for Coimbatore showing the distribution of wind direction and
wind speed during a year are shown in Figure-4.1.
FIGURE-4.1
WIND ROSE DIAGRAMS
C-6.4%
2.4% WSW
08-30hrs
17-30hrs
13.9
% S
W
18.6
% S
SW
2.2
% S S
E 7.0%
E 1.3%
ENE 3.1%NE 3
.8%
NN
E 2
6.6
%
N 2
.7%0
.8%
NN
W
5.1% N
W
1.8% WNW
1.3% W
C-12.4%
SS
E 2
.8%
ESE 0.6%
4.7%
SW
0.9% N
W
0.3
% N
NW
NN
E 9
.3%
19.0
% S
SW
2.3% WSW
10
.4%
S
6.9% W
ESE 1.5%
SE 5.1%S
SE
6.1
%
ENE 4.0%
E 13.0%
N 3
.2%
NE 0
.9%
0% WNW
19
SPEED CALM
1 5 11
SCALE 4%
>19 Km/hr
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The consequences of releases of flammable materials into the atmosphere are
strongly dependent upon the rate at which the released material is diluted and
dispersed to safe concentrations. The rate of dispersion is dependent on the
meteorological conditions prevailing at the time of release, particularly the wind
speed and the degree of turbulence in the atmosphere. The wind direction is also
of importance as it determines the direction in which the cloud of material will
travel. Meteorological data are thus required at two stages of the risk analysis.
Firstly, various parts of the consequence modelling require specification of wind
speed and atmospheric stability. Secondly, the impact calculations require wind-
rose frequencies for each combination of wind speed and stability specified.
The primary requirement is to choose a suitable number of combinations of wind
speed ranges and stabilities for the dispersion modelling. The procedure is to
group these combinations into representative weather classes which together
cover all conditions observed.
Whilst speed and direction are clear in definition, stability is not a widely used
term. Stability is determined by the temperature gradient in the lowest tens of
metres of the atmosphere; this in turn depends on the heating (in the day) or
cooling (at night) at the ground and on the mean wind speed. The stability
determines the degree of turbulence in the atmosphere and hence of mixing-in of
air to a released gas cloud by ambient turbulence: very unstable conditions
(occurring in the middle of a calm, sunny day) lead to much turbulence and
hence rapid dispersion while very stable conditions (occurring on a clear night)
inhibit turbulence and hence dispersion. Stability is conventionally classified by
Pasquill stability classes, denoted A to F.
Table-4.4 shows the typical split of Pasquill Stability categories according to
surface wind speed and atmospheric conditions.
TABLE-4.4
DEFINITION OF PASQUILL STABILITY CLASSES
Surface Wind
Speed (m/s)
Insolation Day Time Night Sky
Strong Moderate Thinly Overcast <3/8 Cloud
< 2 A A/B - -
2-3 A/B B E F
3-5 B B/C D E
5-6 C C/D D D
> 6 C D D D
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Atmospheric stability categories A (very unstable), D (neutral) and F (stable) are
described below.
Category A (very unstable) occurs typically on a warm sunny day with light winds
and almost cloudless skies when there is a strong solar heating of the ground and
the air immediately above the surface. Bubbles of warm air rise from the ground
in thermals. The rate of change (decline) of temperature with height (lapse rate)
is very high.
Category D (neutral) occurs in cloudy conditions or whenever there is a strong
surface wind to cause vigorous mechanical mixing of the lower atmosphere.
Category F (stable) occurs typically on a clear, calm night when there is a strong
cooling of the ground and the lowest layers of the atmosphere by long wave
radiation. There is a strong inversion of temperature (i.e. warm air over cold
air).
The data needed for this study should be split by wind speed, wind direction
stability class and day/night conditions. The weather data used in present
analysis and presented in Table-4.5.
TABLE-4.5
WEATHER CATEGORIES FOR RISK ANALYSIS
Description Unit Weather #1 Weather #2 Weather #3
Temperature C 25 35 35
Relative humidity % 70 70 70
Wind speed m/s 2 3 5
Atmospheric stability - F D D
4.5 Consequence Analysis Results
In BPCL Irugur Terminal, the hazards are mainly pool fire and/or vapour cloud
explosion due to accidental release of flammable liquids such as MS, HSD, SKO,
Ethanol, etc.
Pool Fire Heat Radiation
The effects of heat radiation from pool fire are shown in the following Table-4.6.
TABLE-4.6
EFFECTS OF HEAT RADIATION
Heat Radiation Level
(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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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 ignited, the result is a
vapour cloud explosion (VCE).
In BPCL Iruguru Terminal large release of MS product in the worst case scenario
involving catastrophic tank failure has potential for vapour cloud explosion (VCE).
The damage effect of VCE is due to overpressure,
The effects of overpressure due to VCE are shown in the following Table 4.7.
TABLE 4.7
EFFECTS OF OVERPRESSURE
Over-pressure
Observed Effect bar(g) psig
0.021 0.3 “Safe distance” (no serious damage below this value);
some damage to house ceilings; 10% of window glass
broken.
0.069 1 Repairable damage; partial demolition of houses, made
uninhabitable; steel frame of clad building slightly
distorted.
0.138 2 Partial collapse of walls of houses.
0.207 3 Heavy machines (3000 lb) in industrial buildings
suffered little damage; steel frame building distorted
and pulled away from foundations.
Results of consequence analysis by Phast software for significant scenarios
relevant to Iruguru Terminal are shown in the Table-4.8. Graphical results of
consequence analysis plotted on the site map are also presented in the following
pages.
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TABLE 4.8
CONSEQUENCE ANALYSIS RESULTS
Description Downwind Effect Distances (Metres)
Wind speed & Atm. Stability class 2 m/s; F 3 m/s; D 5m/s; D
New Tanks
MS Tank T-20 (Floating Roof)
Dyke fire heat radiation intensity
4 kW/m2 103 109 122
12.5 KW/m2 42 42 44
37.5 kW/m2 Not reached Not reached Not reached
VCE Overpressure
0.021 barg (0.3 psig) 329 254 174
0.069 barg (1 psig) 204 196 118
0.207 barg (3 psig) Not reached Not reached Not reached
HSD Tank T-21 (Cone Roof)
Dyke fire heat radiation intensity
4 kW/m2 100 106 116
12.5 KW/m2 42 42 44
37.5 kW/m2 Not reached Not reached Not reached
Existing Tanks
MS Tank T-1 (Floating Roof)
Dyke fire heat radiation intensity
4 kW/m2 103 109 122
12.5 KW/m2 42 42 44
37.5 kW/m2 Not reached Not reached Not reached
HSD Tank T-3 (Floating Roof)
Dyke fire heat radiation intensity
4 kW/m2 100 106 116
12.5 KW/m2 42 42 44
37.5 kW/m2 Not reached Not reached Not reached
HSD Tank T-7 (Floating Roof)
Dyke fire heat radiation intensity
4 kW/m2 100 106 116
12.5 KW/m2 42 42 44
37.5 kW/m2 Not reached Not reached Not reached
Pipeline Pump Discharge Leak (20 mm) - MS
Pool fire heat radiation intensity
4 kW/m2 46 49 53
12.5 KW/m2 18 18 20
37.5 kW/m2 Not reached Not reached Not reached
VCE Overpressure
0.021 barg (0.3 psig) 100 124 114
0.069 barg (1 psig) 49 58 55
0.207 barg (3 psig) Not reached Not reached Not reached
Rail tank wagon loading – HSD/ MS leak
Pool fire heat radiation intensity
4 kW/m2 59 64 67
12.5 KW/m2 30 32 37
37.5 kW/m2 Not reached Not reached Not reached
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FIGURE 4.2
DYKE FIRE - MS TANK (T-20) POOL FIRE RADIATION INTENSITY
Observations:
In case of pool fire in dyke due to failure of new MS tank T-20, the heat radiation
intensity 12.5 kW/m2 falls on adjacent tank T-6 which therefore will require
cooling by water spray. Heat radiation intensity on other tanks is less than 12.5
kW/m2.
Heat radiation intensity on the tanker truck loading gantry is less than 4 kW/m2.
This provides adequate time to persons working in the gantry for safe escape as
pool fire develops slowly
Rapid Risk Assessment Studies for BPCL Irugur Installation, near Coimbatore, Tamil Nadu
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FIGURE 4.3
MS TANK (T-20) - VAPOUR CLOUD EXPLOSION OVERPRESSURE
Observations:
In case of vapour cloud explosion (VCE) due to failure of new MS tank T-20, there
is no overpressure radii for 0.201 barg (3 psig) which has potential to cause
damage of structure. The explosion overpressure of 0.069 barg (1 psig) also does
not reach the new control room/ substation. The overpressure radii for 0.021
barg (0.3 psig) falls within the terminal boundary.
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VIMTA Labs Limited, Hyderabad 22
FIGURE-4.4
DYKE FIRE – NEW HSD TANK (T-21) POOL FIRE RADIATION INTENSITY
Observations:
In case of pool fire in dyke due to failure of new HSD tank T-21, the heat
radiation intensity on adjacent tank is less than 12.5 kW/m2. This of pool fire heat
radiation intensity within allowable limits and will not cause damage. Heat
radiation intensity radius for 4 kW/m2 falls within the terminal boundary.
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VIMTA Labs Limited, Hyderabad 23
FIGURE-4.5
DYKE FIRE – NEW HSD TANK (T-23) POOL FIRE RADIATION INTENSITY
Observations:
In case of pool fire in dyke due to failure of new HSD tank T-23, the heat
radiation intensity on adjacent tank is less than 12.5 kW/m2. This of pool fire heat
radiation intensity within allowable limits and will not cause damage. Heat
radiation intensity radius for 4 kW/m2 falls within the terminal boundary.
Rapid Risk Assessment Studies for BPCL Irugur Installation, near Coimbatore, Tamil Nadu
VIMTA Labs Limited, Hyderabad 24
FIGURE-4.6
DYKE FIRE – EXISTING MS TANK (T-1) POOL FIRE RADIATION INTENSITY
Observations:
In case of pool fire in dyke due to failure of existing MS tank T-1, the heat
radiation intensity 12.5 kW/m2 falls on adjacent MS tank T-2 which therefore will
require cooling by water spray. Heat radiation intensity on other tanks is less
than 12.5 kW/m2.
Heat radiation intensity on the nearest new fire water tank, fire water pump
house and gantry is less than 4 kW/m2.
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VIMTA Labs Limited, Hyderabad 25
FIGURE-4.7
DYKE FIRE – EXISTING HSD TANK (T-3) POOL FIRE RADIATION INTENSITY
Observations:
In case of pool fire in dyke due to failure of existing HSD tank T-3, the heat
radiation intensity 12.5 kW/m2 falls on adjacent MS tank T-2 and HSD tank T-5
which therefore will require cooling by water spray. Heat radiation intensity on
other tanks is less than 12.5 kW/m2.
Heat radiation intensity on the nearest new fire water tank, fire water pump
house and gantry is less than 4 kW/m2.
Rapid Risk Assessment Studies for BPCL Irugur Installation, near Coimbatore, Tamil Nadu
VIMTA Labs Limited, Hyderabad 26
FIGURE-4.8
DYKE FIRE – EXISTING HSD TANK (T-7) POOL FIRE RADIATION INTENSITY
Observations:
In case of pool fire in dyke due to failure of existing HSD tank T-7, the heat
radiation intensity on adjacent tank MS tank is less than 12.5 kW/m2.
Rapid Risk Assessment Studies for BPCL Irugur Installation, near Coimbatore, Tamil Nadu
VIMTA Labs Limited, Hyderabad 27
FIGURE 4.9
PIPELINE PUMP DISCHARGE LEAK (25 MM)
POOL FIRE RADIATION INTENSITY
Observations:
In case of pool fire due to leak of MS through 25 mm diameter hole in the
discharge of pipeline pump, the pool heat radiation intensity 4 kW/m2 falls inside
the installation boundary.
Rapid Risk Assessment Studies for BPCL Irugur Installation, near Coimbatore, Tamil Nadu
VIMTA Labs Limited, Hyderabad 28
FIGURE 4.10
PIPELINE PUMP DISCHARGE LEAK (25 MM) - VCE OVERPRESSURE
Observations:
In case of vapour cloud explosion (VCE) due to leak of MS through 25 mm
diameter hole in the discharge of pipeline pump, there is no overpressure radii for
0.201 barg (3 psig) which has potential to cause damage of structure.
The control room/ substation building falls outside the overpressure radius for
0.067 barg (1 psig).
The overpressure radii for 0.021 barg (0.3 psig) falls within the terminal
boundary.
Rapid Risk Assessment Studies for BPCL Irugur Installation, near Coimbatore, Tamil Nadu
VIMTA Labs Limited, Hyderabad 29
FIGURE 4.11
RAIL WAGON LOADING ARM LEAK (25 MM)
POOL FIRE RADIATION INTENSITY
Observations:
In case of pool fire due to leak of diesel/MS through 25 mm diameter hole in the
loading arm of rail wagon gantry, the pool heat radiation intensity 4 kW/m2 falls
inside the installation boundary.
Rapid Risk Assessment Studies for BPCL Irugur Installation, near Coimbatore, Tamil Nadu
VIMTA Labs Limited, Hyderabad 30
4.6 RRA Results
4.6.1 Individual Risk
Iso-risk contours for individual risk at BPCL Irugur Terminal due to existing as
well as new facilities including the proposed rail loading gantry are shown in the
Figure-4.11 and FIGURE 4.12.
FIGURE-4.11
ISO-RISK CONTOURS FOR INDIVIDUAL RISK AT BPCL IRUGUR TERMINAL
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VIMTA Labs Limited, Hyderabad 31
FIGURE-4.12
ISO-RISK CONTOURS FOR INDIVIDUAL RISK AT BPCL IRUGUR TERMINAL
(ENLARGED)
Risk contour of 1 x 10-6 per year is within the boundary of Terminal on all sides.
Thus the individual risk to members of the public is less than 1 x 10-6 per year
and falls in the Acceptable region.
Rapid Risk Assessment Studies for BPCL Irugur Installation, near Coimbatore, Tamil Nadu
VIMTA Labs Limited, Hyderabad 32
The maximum iso-risk contour in the Terminal is 1 x 10-5 per year in the pump
houses and inside some dykes. Personnel are expected to be in the pump houses
for long periods whereas normal work inside dyke area is expected to be only for
very short periods.
By taking risk transect, the maximum individual risk in pump houses is found to
be 1.2 x 10-5 per year.
This corresponds to risk a person standing at the location all the time during the
year.
As the work is limited to 8 hours in a day, the maximum individual risk to person
working in the depot will be
(1.2 x 10-5) x (8/24) = 4 x 10-6 per year.
This is in the lower part of “as low as reasonably practicable (ALARP)” region as
shown in Figure 4.13.
Rapid Risk Assessment Studies for BPCL Irugur Installation, near Coimbatore, Tamil Nadu
VIMTA Labs Limited, Hyderabad 33
FIGURE-4.13
INDIVIDUAL RISK AT BPCL IRUGUR TERMINAL
Intolerable Risk
Risk Tolerable if ALARP
Broadly Acceptable
10-3
per year
10-6
per year
10-4
per year
Risk to Personnel
Risk to Public
Max. Individual Risk to Personnel:
4 x 10-6
per year Max. Individual Risk to
Public: 1 x 10-6
per year
Rapid Risk Assessment Studies for BPCL Irugur Installation, near Coimbatore, Tamil Nadu
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4.6.2 Societal Risk
The FN Curve for societal risk at BPCL Irugur Terminal is shown in Figure-4.14.
FIGURE-4.14
SOCIETAL RISK AT BPCL IRUGUR TERMINAL
It is seen that the societal risk is well within the Acceptable region.
Rapid Risk Assessment Studies for BPCL Irugur Installation, Coimbatore, Tamil Nadu
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5.0 CONCLUSIONS & RECOMMENDATIONS
5.1 Conclusions
The results of this RRA study for the complete BPCL Irugur Terminal including the
existing facilities and new facilities for pumping of white oil products by Irugur –
Bengaluru Pipeline lead to the following conclusions.
Individual risk to members of the public is less that 1 x 10-6 per year and
therefore in the Acceptable level.
Maximum individual risk to personnel working in the Terminal is 4 x 10-6 per
year, which is in the lower part of “As low as reasonably practicable (ALARP)”
region.
Societal risk is generally in the Acceptable region.
Consequence analysis for worst case scenarios and maximum credible scenarios
indicates that the significant effect distances for pool fire heat radiation intensity
and vapour cloud explosion overpressure fall within the terminal boundary and
are not expected to cause major damage of equipment and structures.
The above results indicate that BPCL Irugur Terminal conforms well to the risk
criteria. BPCL are expected to ensure the best practices for safety management
system, engineering, construction, operation and maintenance for the Terminal.
The installation design and construction conform to relevant Indian and
international codes & standards including OISD standards. In particular the
following safety features are note-worthy:
Layout of the Terminal is properly made conforming to OISD guidelines.
Adequate fire protection facilities including fire water storage and pumps are
provided.
The Terminal is continuously manned all the time so that any incidence of rim
seal fire in floating roof tanks can be handled without delay.
5.2 Recommendations
The following recommendations are provided to ensure that the safety standards
are in line with the current best industry practices.
Remote operated valves are to be provided in each pipe connecting to the
tank bottom. These valves are independent of the valves used for normal tank
transfer operation.
Reliable tank level instrumentation, alarm and safety interlock system need to
be provided using guided wave radar type level transmitters. The tank overfill
protection system should be independent of the tank gauging system to
ensure multiple independent protection layers to prevent tank overfill hazard.
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Fixed water spray system is to be provided for MS tanks as per OISD
guidelines.
Semi-fixed foam system with suitable heat detection and alarm system for the
rim seal is provided for the floating roof tanks storing MS product to ensure
timely application of foam to prevent escalation of rim seal fires.
Emergency push buttons to stop loading pumps and close tank outlet valves
are to be provided at safe locations in the Terminal to limit the quantity of fuel
released in case of a leak. This is required for rail wagon loading gantry also.
It shall be ensured that the instruments and electrical fittings installed in the
terminal conform to the electrical hazardous area classification. Special
attention is required in maintenance of explosion-proof electrical equipment.
Suitable arrangement for containment and collection of spillages are to be
provided in loading area.
Tank dykes should be maintained in sound condition without openings or
cracks. The dyke drain valves are to be kept closed except during rain.
Alcohol-resistant foam is available at the installation for use in fighting ethanol
fire.
A Committee headed by Mr. M. B. Lal constituted by MoPNG has made
valuable recommendations in its report dated September 2009 on the Jaipur
fire incident. It shall be ensured that all relevant recommendations are
incorporated in the design, construction, operation and maintenance of the
installation.
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