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RAPID RISK ASSESSMENT STUDY
FOR RE-ROUTING OF OIL PRODUCT PIPELINES IN
CHENNAI
RRA - PIPELINE PROJECT
Submitted to:
Indian Oil Corporation Limited Chennai
Submitted 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)
May 2015
Rapid Risk Assessment Study for Re-Routing of Oil Product Pipelines in Chennai
VIMTA Labs Limited, Hyderabad 2
1.0 INTRODUCTION
1.1 Background
Indian Oil Corporation Limited (IOCL) propose to lay three underground pipelines
about 5.45 km long between IOC Korukkupet and Foreshore Terminals in North
Chennai to replace the existing lines which pass through densely populated areas
and are difficult to maintain.
These lines are used for both export from CPCL, import and coastal positioning of
HSD during shortfall in CPCL production to meet the demand of Tamil Nadu, Pondicherry UT and parts of adjoining states. The Fuel Oil line is used for
positioning product at FST from CPCL for bunkering as well as for export from
Chennai port. Similarly the Lube line is used for export from CPCL and import of
base oils as well as extracts. Thus these dock lines play a vital role in evacuation
of CPCL production and also receive through coastal movement to meet local
demand during shortfall in production/shut down period. Besides meeting the
public demand for MS/HSD, these lines also cater to requirement of PDS, all
thethree wings of Defence, Coast Guard, Para military, Civil Aviation, Bunkering
requirements for merchant navy ships, major customers like power plants,
Railways, State Transport sectors, Fertilizer plants etc.
Taking into consideration the vital requirement of these lines on the one hand and
the challenge of maintaining the lines passing through densely populated areas on
the other hand, it is proposed to re-route the lines between IOC Korukkupet and
IOC Foreshore Terminal in North Chennai.
In a PIL case filed in National Green Tribunal Chennai (NGT), Chennai after the
incident of contamination of water in the bore well/wells near underground oil
pipelines, Ministry of Petroleum & Natural Gas (MOP&NG) as one of the
respondents made commitment on behalf of Oil Manufacturing Companies as per
which, IOC would be required to take action for re-routing of the underground
portion of the dock lines in the Railway corridor.
1.2 RRA Study
IOCL being an organization with commitment to high standards of process safety
management wish to identify the hazards associated with the re-routing of oil
pipelines in North Chennai and implement all necessary measures to ensure that
the risk due to the pipelines are kept as low as reasonably practicable. With this
objective, IOCL have engaged the services of Vimta Labs, Hyderabad, for carrying
out a Rapid Risk Assessment (RRA) study for the re-routing of pipelines in North
Chennai.
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.
This report contains the Rapid Risk assessment (RRA) for the IOCL pipelines re-routing project in North Chennai.
Rapid Risk Assessment Study for Re-Routing of Oil Product Pipelines in Chennai
VIMTA Labs Limited, Hyderabad 3
2.0 FACILITY DESCRIPTION
2.1 Replacement & Rerouting of IOCL Pipelines in North Chennai
The pipelines will be routed in a corridor 4 m wide along the Railway tracks
between Korukkupet and Chennai Port entry, where IOCL already have 1.6 m
width. As per OISD guidelines, in 4 m width, maximum 3 pipelines can be
accommodated. In compliance with the OISD norms, against the presently
existing 4 lines, it is proposed to lay the following 3 pipelines to meet the
requirements.
1) 20” diameter line for White Oil products MS, HSD, ATF, Naptha, SKO as a
multiproduct line
2) 14” diameter line for Black Oil (Fuel Oil)
3) 12” diameter line for Lube Oils
The pipelnes cater to the following throughputs:
White Oil products : 1.1 MMTPA
Black Oil products : 0.7 MMTPA
Lube Oil products : 0.3 MMTPA
All the pipelines will be piggable to facilitate smooth operation and maintenance.
As per the pipeline operations, maximum operating pressure shall not exceed 7
kg/sq.cm. However for the calculation purpose 12 kg/sq.cm. maximum operating
pressure is considered.
API 5L X46 grade pipes have been chosen. Accordingly the thickness required and
maximum allowable operating pressure for the pipelines are as follows:
Pipeline
diameter
(inch)
Thickness
of pipeline
considered
(inch)
Thickness required
for maximum
operating pressure
(inch)
Actual
operating
pressure
considered
(kg/sq.cm.)
Maximum
allowable
operating
pressure
(kg/sq.cm.)
20 0.281 0.07419 12 45.45
14 0.281 0.05193 12 64.93
12.75 0.281 0.04729 12 71.29
Thus pipes are of higher wall thickness and MAOP much higher than the required.
Further corrosion mitigation measures are implemented.
The terrain along the pipeline route is mostly flat and plain. At 3 locations it
crosses the railway track. There are also 3 road crossings. At rail crossings,
where casing pipe would be provided, the pipe wall thickness would remain same
as that for the main pipeline as per the standards. For Horizontal Directional
Drilling (HDD) technique at road crossings, higher wall thickness pipes are
considered. There is no crossing of water course. Entire relaying/re-routing is
planned to be laid underground with effective cover of minimum 1.2 M below the
ground level.
Rapid Risk Assessment Study for Re-Routing of Oil Product Pipelines in Chennai
VIMTA Labs Limited, Hyderabad 4
The route map of re-routed pipelines are provided in Annexure – I.
The proposed pipelines will be hooked up to the existing pipeline system at
Korukkupet exchange pit. Scraper facilities shall be provided at Foreshore and
Korukkupet Terminals. Necessary surge relief system and thermal relief valves are
provided for safety with underground storage for the released oil.
Suitable Mass Flow Meters (MFMs) shall be provided at Korukkupet and Foreshore
Terminals to measure the incoming and outgoing flow.
FST and Korukkupet would be provided with hot standby PLC based station
control system to perform local control functioning and to monitor and control
The field instrumentation at FST & Korukkupet stations would comprise pressure
transmitters, pressure switches, pressure gauges, mass flow meters, temperature
gauge, temperature transmitter, scraper detector, emergency shut down switches
etc.
Station Control Centre (SCC) would have workstations as operator interface to
the station instrumentation and control system, on dual local area network (LAN)
in client server mode.
230 V UPS system with dual battery back up would be provided at Korukkupet
and Foreshore Terminal.
Optical fibre cable shall be laid along with the main line which will be connected
through a Ethernet cum land switch at both the ends. The same shall be used for
data transfer between the 2 stations.
Through Optical Fibre network the PLC system for automation shall be hooked up
through LAN network. A separate server shall be integrated with the automation
system. The requisite information for the purpose of control and monitoring of
the pipeline shall be acquired with suitable application software installed in the
server. Leak detection software also shall be installed in the server which will
collect the data from the system and work on a real time basis.
Fire detection & alarm system: For the Control building, smoke detectors and
rate of rise (RoR) heat detectors along with Fire Alarm Panel and SIL-2 rated PLC
with HMI have been considered for all attended stations.
Fire Suppression system: Besides portable Fire extinguishers, CO2 flooding would
be provided in cable trenches, hydrants. Water monitors would be provided
suitably in the piping area. The numbers and type of extinguisher would be in line
with OISD 214.
Hydrants and Water monitors would be provided suitably in the piping area.
Firewater network (with required number of Water monitors and hydrants with
double landing valves) would be provided. Medium Velocity Water Sprinkler
system considered for piping and metering and scrapper barrel area.
Rapid Risk Assessment Study for Re-Routing of Oil Product Pipelines in Chennai
VIMTA Labs Limited, Hyderabad 5
3.0 SCOPE, OBJECTIVE & METHODOLOGY
3.1. Scope
The scope of this RRA study covers the three underground pipelines (20”, 14” and
12.75”) for white oil, black oil and lube oil to be installed adjacent to the railway
track between Korukkupet and Foreshore Terminals in North Chennai.
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 pipeline system
• 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.
Rapid Risk Assessment Study for Re-Routing of Oil Product Pipelines in Chennai
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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.
Rapid Risk Assessment Study for Re-Routing of Oil Product Pipelines in Chennai
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3.3.2 Rapid Risk Analysis (RRA)
The Rapid Risk Analysis (RRA) is carried out using the renowned DNV software
Phast Risk Micro (previously known as SAFETI Micro) version 6.7.
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 UK Onshore Operator’s Association (UKOPA).
UK Onshore Operator’s Association (UKOPA) 1962-2012. It presents
collaborative pipeline and product loss incident data from onshore Major
Accident Hazard Pipelines (MAHPs) operated by National Grid, Scotia Gas
Network, Wales & West Utilities, Shell UK, BP, Huntsman and E-ON UK,
covering operating experience up to the end of 2012. The overall failure
frequency over the period 1962 to 2012 is 0.227 incidents per 1000
Km/year. (Ref. UKOPA Report No UKOPA/13/0047 issued December 2013).
The failure frequency over the last 20 years is 0.080 incidents per 1000 km.
year. For the last 5 years the failure frequency is 0.122 incidents per 1000
km. year, whilst in the previous report this figure was 0.108 incidents per
1000 km. year (covering the 5 year period up to the end of 2011).
Selection of Failure Frequency Database
UKOPA database is selected for this QRA study. It has by far the greatest
detail, and enables great flexibility of analysis because of failure distribution
with reference to causes. It gives the details in a format readily used in QRA.
The database is designed to reflect the ways in which the UKOPA operators
design, build, operate, inspect and maintain their pipeline systems. Although
the pipeline and failure data are extensive, there are pipeline groups (e.g. large
diameter, recently constructed pipelines) on which no failures have occurred;
however, it is unreasonable to assume that the failure frequency for these
pipelines is zero. Similarly, further pipeline groups exist for which the historical
failure data are not statistically significant.
UKOPA database contains extensive data on pipeline failures and on part-wall
damage, allowing prediction of failure frequencies for pipelines for which
inadequate failure data exist.
For these reasons, it was chosen as the main source of failure information for
this study
Rapid Risk Assessment Study for Re-Routing of Oil Product Pipelines in Chennai
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Failure Data Analysis
The total length of Major Accident Hazard Pipelines, above ground, below
ground and elevated, in operation at the end of 2012 for all participating
companies (National Grid, Scotia Gas Network, Northern Gas Network, Wales
and West Utilities, BP, Shell UK, Huntsman and E-ON UK) is 22,113 km. The
total exposure in the period 1952 to the end of 2012 is about 8, 32,775 km.yr.
Transported Products
The lengths of pipeline in operation at the end of 2012, by transported product,
are shown in Table below.
Table : Transported Products in Pipelines (km)
Natural Gas (Dry) 20,344 Propylene 38.0
Ethylene 1,140 Condensate 24.0
Natural Gas Liquids 251 Propane 20.0
Crude Oil (Spiked) 224 Butane 20.0
Ethane 38
Hydrogen 14 TOTAL 22,113
Ignition
There were 9 out of 189 (~5%) product loss incidents that resulted in ignition.
Table below provides more detail:
Table: Incidents that resulted in Ignition
Affected
Component Cause Of Fault Hole Diameter Class
Pipe Seam Weld Defect 0-6 mm
Pipe Ground Movement Full Bore and Above
(18” Diameter Pipe)
Pipe Girth Weld Defect 6-20 mm
Pipe Unknown 6-20 mm
Pipe Pipe Defect 0 – 6 mm
Pipe Unknown 40 – 110 mm
Pipe Lightning Strike 0-6 mm
Bend Internal Corrosion 0-6 mm
Bend Pipe Defect 6-20 mm
The overall ignition probability in the present analysis has therefore been taken
as 0.05.
Rapid Risk Assessment Study for Re-Routing of Oil Product Pipelines in Chennai
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The overall incident frequency by hole size over the period 1962 - 2012 is
shown in Table below
Table: Failure Frequency distribution by hole size
Hole Size Class Number of
Incidents
Frequency [Incidents
per 1000 km.yr]
Full Bore* and Above 7 0.008
110mm – Full Bore* 3 0.004
40mm – 110mm 7 0.008
20mm – 40mm 23 0.028
6mm – 20mm 31 0.037
0 – 6mm 116 0.139
Unknown 2 0.002
Total 189 0.227
Rapid Risk Assessment Study for Re-Routing of Oil Product Pipelines in Chennai
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Incident Frequency by cause
Table: Products loss Incidents by Cause
Product Loss Cause No. of Incidents
Girth Weld Defect 34
External Interference 41
Internal Corrosion 2
External Corrosion 41
Unknown 7
Other 41
Pipe Defect 13
Ground Movement 7
Seam Weld Defect 3
Total 189
Figure: Products Loss Incidents by Cause - Historical
Rapid Risk Assessment Study for Re-Routing of Oil Product Pipelines in Chennai
VIMTA Labs Limited, Hyderabad 11
An overview of the product loss incident frequency by cause and size of leak in
the period 1962 to 2012 is shown in Figure below.
Figure: Products Loss Incidents by Cause & Leak Size
* Full Bore = diameter of pipeline
# Equivalent hole diameter is the circular hole diameter in mm with an area
equivalent to the observed (usually non-circular) hole size
Rapid Risk Assessment Study for Re-Routing of Oil Product Pipelines in Chennai
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External Interference
External Interference by Diameter Class
Figure below shows the product loss incident frequencies associated with
external interference by diameter class and by hole size.
Figure: Products Loss Incidents by External Interference – Diameter
Class
Table: Exposure by Diameter Class
Diameter
inches
Exposure
km.yr Incidents Frequency/1000km.yr
0-4 41098 5 0.122
5-10 170268 20 0.117
12-16 138055 9 0.065
18-22 121019 3 0.025
24-28 134607 3 0.022
30-34 39945 1 0.025
36-48 186783 0 0.000
Total 832775 41 0.049
Rapid Risk Assessment Study for Re-Routing of Oil Product Pipelines in Chennai
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External Interference by Measured Wall Thickness Class
The relationship between product loss incidents caused by third party
interference and wall thickness is shown in Figure below.
Figure: Products Loss Incidents by External Interference - Wall
Thickness Class
Table: Exposure by Wall Thickness Class
Wall
Thickness
mm
Exposure
km.yr Incidents
Frequency
/1000 km.yr
<5 54775 13 0.237
5-10 392241 24 0.061
10-15 318941 4 0.013
>15 66818 0 0.000
Total 832775 41 0.049
Rapid Risk Assessment Study for Re-Routing of Oil Product Pipelines in Chennai
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External Interference by Area Classification
Figure: Products Loss Incidents by External Interference – Area
Classification
Table: Exposure by Area Classification in km. yr.
Area
Classification
Exposure
km.yr Incidents
Frequency /1000
km.yr
Rural 754858 30 0.040
Suburban 76847 11 0.143
Urban 1069 0 0.000
Total 832775 41 0.049
Rapid Risk Assessment Study for Re-Routing of Oil Product Pipelines in Chennai
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External Corrosion by Wall Thickness Class
Figure: Products Loss Incidents by External Corrosion - Wall Thickness
Class
Table: Exposure by Wall Thickness Class
Wall Thickness
mm Exposure km. yr Incidents
Frequency/
1000 km. yr
<5 54775 24 0.438
5-10 392241 16 0.041
10-15 318941 0 0.000
>15 66818 0 0.000
Total 811923 40 0.048
Rapid Risk Assessment Study for Re-Routing of Oil Product Pipelines in Chennai
VIMTA Labs Limited, Hyderabad 16
External Corrosion by External Coating Type
Figure: Products Loss Incidents by External Corrosion – Coating Type
Table: Exposure by External Coating Type
External
Coating
Exposure
km.yr Incidents
Frequency /
1000 km.yr
Bitumen 30798 3 0.097
Coal Tar 597009 26 0.044
Polyethylene 79704 4 0.050
FBE 84111 0 0.000
Other/Unknown 41153 8 0.194
Total 832775 41 0.049
Rapid Risk Assessment Study for Re-Routing of Oil Product Pipelines in Chennai
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External Corrosion by Type of Backfill
Figure: Products Loss Incidents by External Corrosion – Backfill Type
Rapid Risk Assessment Study for Re-Routing of Oil Product Pipelines in Chennai
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Estimating IOCL Pipeline Failure Frequency
The overall failure frequency reported in UKOPA database is 0.227 incidents per
1000 km. year over the period 1962 to 2011, and 0.122 incidents per 1000
km.year the last 5 years.
The failure frequency for IOCL Pipeline is estimated by applying suitable
adjustment factors to UKOPA data as shown in Tables.
Pipeline size : 14 inches
Operating Pressure : 7 bar
Area Classification : Rural
Table: Failure Frequency Adjustment Factors for 14” IOCL Oil Pipeline
Adjustment Factors for Pipeline Failure Frequency
S.
No.
Parameter Actual
Value
Ratio: Actual
value/ Database
Value
Adjustment
factor
1.0 External
Interference
1.1 Diameter class 14 inches 0.065 / 0.049 1.326
1.2 Wall thickness class 7.1 mm 0.061 / 0.049 1.244
1.3 Area classification Rural 0.040 / 0.049 0.816
Avg. factor for
external
interference
1.128
2.0 External
Corrosion
2.1 Wall thickness class 7.1 mm 0.041 / 0.048 0.854
2.2 Coating type 3 LPE 0.050/0.049 1.020
2.3 Backfill type 1.000
2.4 Year of Construction 1.000
Avg. factor for
external corrosion
0.968
3.0 Internal corrosion 1.0
4.0 Pipe defect 1.0
5.0 Girth weld defect 1.0
6.0 Seam weld defect 1.0
7.0 Ground
movement
1.0
Rapid Risk Assessment Study for Re-Routing of Oil Product Pipelines in Chennai
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Table: Adjusted Failure Frequency for 14” IOCL Oil Pipeline
Adjusted Pipeline Failure Frequency for Pipeline
S.
No.
Cause Incidents in UKOPA Data
base (Ref: Table 6)
Adjustment
factor for
14” IOCL
Oil Pipeline
Adjusted
Factor for
14” IOCL
Oil Pipeline No. of
Incidents
Fraction
1. External
interference 41 0.217 1.128 0.244
2. External corrosion 41 0.217 0.968 0.210
3. Internal corrosion 2 0.011 1 0.011
4. Pipe defect 13 0.069 1 0.069
5. Girth weld defect 34 0.180 1 0.180
6. Seam weld defect 3 0.016 1 0.016
7. Others 41 0.217 1 0.217
8. Unknown 7 0.037 1 0.037
9 Ground Movement 7 0.037 1 0.037
Total Incidents 189 1.000 1.021
Base failure
frequency (UKOPA
– last 5 yrs.)
0.122 per 1000 km.yr
Adjusted failure
frequency for 14”
IOCL Oil Pipeline
0.122 x 1.021
= 0.125 per 1000 km.yr (1.25 x 10-4 per km.yr)
Rapid Risk Assessment Study for Re-Routing of Oil Product Pipelines in Chennai
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Pipeline size :20 inches
Operating Pressure : 7 bar
Area Classification : Rural
Table: Failure Frequency Adjustment Factors for 20” IOCL Oil Pipeline
Adjustment Factors for Pipeline Failure Frequency
S.
No.
Parameter Actual
Value
Ratio: Actual
value/ Database
Value
Adjustment
factor
1.0 External
Interference
1.1 Diameter class 14 inches 0.065 / 0.049 0.510
1.2 Wall thickness class 7.1 mm 0.061 / 0.049 1.244
1.3 Area classification Rural 0.040 / 0.049 0.816
Avg. factor for
external
interference
0.856
2.0 External
Corrosion
2.1 Wall thickness class 7.1 mm 0.041 / 0.048 0.854
2.2 Coating type 3 LPE 0.050/0.049 1.020
2.3 Backfill type 1.000
2.4 Year of Construction 1.000
Avg. factor for
external corrosion
0.968
3.0 Internal corrosion 1.0
4.0 Pipe defect 1.0
5.0 Girth weld defect 1.0
6.0 Seam weld defect 1.0
7.0 Ground
movement
1.0
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Table: Adjusted Failure Frequency for 20” IOCL Oil Pipeline
Adjusted Pipeline Failure Frequency for Pipeline
S.
No.
Cause Incidents in UKOPA Data
base (Ref: Table 6)
Adjustment
factor for
20” IOCL
Oil Pipeline
Adjusted
Factor for
20” IOCL
Oil Pipeline No. of
Incidents
Fraction
1. External
interference 41 0.217 0.856 0.185
2. External corrosion 41 0.217 0.968 0.210
3. Internal corrosion 2 0.011 1 0.011
4. Pipe defect 13 0.069 1 0.069
5. Girth weld defect 34 0.180 1 0.180
6. Seam weld defect 3 0.016 1 0.016
7. Others 41 0.217 1 0.217
8. Unknown 7 0.037 1 0.037
9 Ground Movement 7 0.037 1 0.037
Total Incidents 189 1.000 0.962
Base failure
frequency (UKOPA
– last 5 yrs.)
0.122 per 1000 km.yr
Adjusted failure
frequency for 20”
IOCL Oil Pipeline
0.122 x 0.962
= 0.118 per 1000 km.yr (1.18 x 10-4 per km.yr)
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RISK ANALYSIS
The results of Rapid 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 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 the following Figure
3.7.
FIGURE-3.7
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.
Rapid Risk Assessment Study for Re-Routing of Oil Product Pipelines in Chennai
VIMTA Labs Limited, Hyderabad 23
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
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.
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 3.8.
FIGURE-3.8
INDIVIDUAL RISK CRITERIA
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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
3.9.
Figure 3.9: 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 IOCL Pipelines in
North Chennai
TABLE-4.1
FAILURE SCENARIOS AND THE RELEVANT INPUT DATA
Item
Description
Failure Scenario Fraction
of Total
Failure
Total Failure
Rate
(per km.year)
White Oil
Pipeline
(20”)
Small leak: 5 mm dia
Medium leak: 25 mm dia
Large leak: 100 mm dia
Full bore leak
60%
25%
10%
5%
1.18 E-04
Black Oil
Pipeline
(14”)
Small leak: 5 mm dia
Medium leak: 25 mm dia
Large leak: 100 mm dia
Full bore leak
60%
25%
10%
5%
1.25 E-04
4.2 Population Data
The population across pipeline route is as shown in Table 4.2.
TABLE 4.2
Population Data – IOCL North Chennai Pipeline Route
Area Population
0 – 3 km 8.50 lakhs
3 – 7 km 14.24 lakhs
7 – 10 km 9.81 lakhs
4.3 Ignition Source Data
The following ignition sources are considered along the pipeline route.
- Railway line
- Roads
Appropriate data for traffic density and speed are used for input to Phast
software.
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4.3 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, IMD CHENNAI (MINAMBAKKAM)
Month Temperature (0C) Rainfall (mm)
Max. Min. Monthly Total
January 28.8 20.4 35.3
February 30.5 21.1 13.0
March 32.6 23.0 14.5
April 34.7 25.8 15.9
May 37.4 27.6 42.4
June 37.3 27.4 53.9
July 35.3 26.1 99.6
August 34.5 25.5 129.9
September 33.9 25.2 123.5
October 31.8 24.2 284.6
November 29.4 22.6 353.0
December 28.4 21.2 146.3
Source: India Meteorological Department, Pune
Wind rose diagrams for the site showing the distribution of wind direction and
wind speed during a year are shown in the following figures.
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FIGURE 4.1: ANNUAL WIND ROSE DIAGRAM – IMD, CHENNAI
(MINAMBAKKAM)
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4.5 Consequence Analysis Results
In case of leaks from the IOCL Pipeline in North Chennai, the hazards are mainly
pool fire and/or explosion due to accidental release of flammable liquids MS, HSD,
ATF, Naptha, SKO and Fuel Oil.
Pool fire heat radiation
The effects of heat radiation from pool fire are shown in the following Table 4.4.
TABLE 4.4
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.
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 case of large release of MS or Naphtha from pipeline there is 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 4.5.
TABLE-4.5
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.
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Consequence analysis for leaks in the IOCL pipelines in North Chennai has been
carried out for the following case:
• Leak from 25 mm diameter hole representing maximum credible scenario
Results of consequence analysis by Phast software for the above scenarios are
shown in the Table-4.6.
TABLE-4.6
CONSEQUENCE ANALYSIS RESULTS – MAX. CREDIBLE SCENARIOS
Description Downwind Effect
Distances (Metres)
Wind speed & Atm. Stability class →→→→ 3 m/s; D
Product: MS
Leak Size: 25 mm
Pool fire heat radiation intensity
4 kW/m2 41.3
12.5 KW/m2 20.6
37.5 kW/m2 8.4
Vapour cloud explosion overpressure
0.021 bar (0.3 psi) -
0.069 bar (1 psi) -
0.207 bar (3psi) -
Product: HSD
Leak Size: 25 mm
Pool fire heat radiation intensity
4 kW/m2 40.5
12.5 KW/m2 20.2
37.5 kW/m2 8.2
Vapour cloud explosion overpressure
0.021 bar (0.3 psi) -
0.069 bar (1 psi) -
0.207 bar (3psi) -
With respect to VCE scenario, it is to be noted that on the entire stretch lines are
laid minimum 1.5 m below ground level and there is a on-time monitoring of flow
characteristics and hence likelihood of accumulation of MS product on the surface
is very remote.
Graphical results of consequence analysis plotted on pipeline route map are
provided in Annexure – II.
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4.6 RRA Results
4.6.1 Individual risk
Iso-risk contours for individual risk along pipeline route near populated areas are
shown in the following Figure 4.2. 4.3. 4.4 and 4.5.
FIGURE-4.2
ISO-RISK CONTOURS FOR INDIVIDUAL RISK – OVERALL ROUTE
1.0E-08 per year
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FIGURE-4.3
ISO-RISK CONTOURS – ENLARGED VIEW FOR INITIAL SECTION
1.0E-08 per year
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FIGURE-4.4
ISO-RISK CONTOURS – ENLARGED VIEW FOR MIDDLE SECTION
1.0E-08 per year
1.0E-07 per year
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FIGURE-4.5
ISO-RISK CONTOURS – ENLARGED VIEW FOR END SECTION
The maximum individual risk contour observed along the pipeline route is 1E-07
per year.
Risk transects at different points show the value of maximum individual risk as
1.1E-07 per year
This is in the “Broadly Acceptable Region” as shown in Figure 4.6.
1.0E-08 per year
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FIGURE-4.6
INDIVIDUAL RISK ALONG IOCL CHENNAI PIPELINE
Intolerable Risk
Risk Tolerable
if ALARP
Broadly
Acceptable
Risk
10-3
per year
10-6
per year
10-4
per year
10-6
per year
Risk to
Personnel
Risk to
Public
Max. Individual Risk to Public: 1.1 x 10-7 per year
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4.6.2 Societal Risk
The FN Curves for societal risk for sections along pipeline route with some nearby
population are shown in Figure 4.7.
FIGURE-4.7
SOCIETAL RISK FOR IOCL PIPELINES
It is seen that the societal risk for the IOCL pipelines in North Chennai is well
within the Acceptable region.
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5.0 CONCLUSIONS & RECOMMENDATIONS
5.1 Conclusions
The results of this RRA study for the re-routed white oil and fuel oil oil pipelines of
IOCL between Korukkupet and Foreshore Terminals lead to the following
conclusions.
• Te maximum individual risk to members of the public is 1.1 X 10-7 per year
which is less than 1 x 10-6 per year and therefore in the Acceptable level.
• Societal risk is generally in the Acceptable region.
Consequence analysis for leaks in the pipeline system indicates that significant
effect distances for pool fire heat radiation intensity fall within 50 metres of the
pipeline for 25 mm leak corresponding to maximum credible scenario.
The pipelines are laid minimum 1.5 m below ground level along the entire stretch
and there is a on-time monitoring of flow characteristics and hence likelihood of
accumulation of MS product on the surface lading to VCE scenario is very remote.
The above results indicate that the re-routed pipelines of IOCL conform well to
the risk criteria. IOCL are expected to ensure the best practices for safety
management system, engineering, construction, operation and maintenance for
the pipeline.
The lube oil line is excluded petroleum as flash point is in the range of 200 °C.
The installation design and construction conform to relevant codes & standards
including OISD and PNGRB guidelines. In particular the following safety features
are note-worthy:
• Routing of pipelines along the railway corridor.
• Selection of design pressure and pipe wall thickness much higher than
normal requirement.
• 100% radiography test for girth welds in the pipelines
• 3-Layer polyethyelene coating on pipelines
• SCADA system and optic fibre cable (OFC) data communication link
• Real time leak detection system for pipeline
• Regular pigging for preventive maintenance which will help to identify the
potential defects and take advance action
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External interference, also termed third party damage, constitutes the main
cause for leaks in pipelines. While necessary provisions such as routing the
pipeline along the railway line and provision of 1.2 m cover for the underground
pipe are in place to minimize the possibility of such leakage in these pipelines,
continuous efforts are required to maintain the systems in effective condition.
These include pipeline markers, frequent patrols, effective liaison with local
communities, utility distribution companies etc.
In case of any leakage in pipeline, it is necessary to isolate the supply with
minimum delay. For this purpose effective communication system with
emergency control centre is to be established.
- - - - x - - - -
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ANNEXURE – 1
IOCL CHENNAI PIPELINE ROUTE MAP
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ANNEXURE – II
CONSEQUENCE ANALYSIS RESULTS
CONSEQUENCE ANALYSIS
Page | 2
1. Pipeline containing HSD
Leak size – 25 mm Weather – Wind speed 3 m/s; Stability D Intensity radii for Pool Fire
CONSEQUENCE ANALYSIS
Page | 5
2. Pipeline containing MS
Leak size – 25 mm Weather – Wind speed 3 m/s; Stability D Intensity radii for Pool Fire