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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

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.

VIMTA Labs Limited, Hyderabad 2


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 Black Oil products Lube Oil products

: 1.1 MMTPA : 0.7 MMTPA : 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:

Thickness Thickness required

Actual Maximum

Pipeline operating allowable of pipeline for maximum

diameter pressure operating considered operating pressure

(inch) considered pressure (inch) (inch)

(kg/sq.cm.) (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.


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.



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.



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.



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



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 Cause Of Fault Hole Diameter Class

Component

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.



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 Frequency [Incidents

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



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



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



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 Exposure Incidents Frequency/1000km.yr

inches km.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 VIMTA Labs Limited, Hyderabad 12


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

Exposure

Frequency Thickness Incidents

km.yr /1000 km.yr mm

15 66818 0 0.000

Total 832775 41 0.049



External Interference by Area Classification Figure: Products Loss Incidents by External Interference – Area Classification

Table: Exposure by Area Classification in km. yr.

Area Exposure Incidents Frequency /1000 Classification km.yr km.yr

Rural 754858 30 0.040

Suburban 76847 11 0.143

Urban 1069 0 0.000

Total 832775 41 0.049



External Corrosion by Wall Thickness Class

Figure: Products Loss Incidents by External Corrosion - Wall Thickness Class

Table: Exposure by Wall Thickness Class

Wall Thickness Exposure km. yr Incidents

Frequency/

mm 1000 km. yr

15 66818 0 0.000

Total 811923 40 0.048



External Corrosion by External Coating Type

Figure: Products Loss Incidents by External Corrosion – Coating Type

Table: Exposure by External Coating Type

External Exposure Incidents

Frequency /

Coating km.yr 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



External Corrosion by Type of Backfill Figure: Products Loss Incidents by External Corrosion – Backfill Type



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. Parameter Actual Ratio: Actual Adjustment

No. Value value/ Database factor

Value

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 1.128

external

interference

2.0 External

Corrosion


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


external corrosion

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 1.0

movement



Table: Adjusted Failure Frequency for 14” IOCL Oil Pipeline

Adjusted Pipeline Failure Frequency for Pipeline S. Cause Incidents in UKOPA Data Adjustment Adjusted

No. base (Ref: Table 6) factor for Factor for

No. of Fraction 14” IOCL 14” IOCL

Incidents Oil Pipeline Oil Pipeline

1. External 41 0.217 1.128 0.244

interference 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 0.122 per 1000 km.yr

frequency (UKOPA

– last 5 yrs.)

Adjusted failure 0.122 x 1.021

frequency for 14” = 0.125 per 1000 km.yr (1.25 x 10-4

per km.yr) IOCL Oil Pipeline



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. Parameter Actual Ratio: Actual Adjustment

No. Value value/ Database factor

Value

1.0 External

Interference

1.1 Diameter class 14 inches 0.065 / 0.049 0.510


1.3 Area classification Rural 0.040 / 0.049 0.816


external

interference

2.0 External

Corrosion


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


external corrosion

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 1.0

movement



Table: Adjusted Failure Frequency for 20” IOCL Oil Pipeline

Adjusted Pipeline Failure Frequency for Pipeline S. Cause Incidents in UKOPA Data Adjustment Adjusted

No. base (Ref: Table 6) factor for Factor for

No. of Fraction 20” IOCL 20” IOCL

Incidents Oil Pipeline Oil Pipeline

1. External

41 0.217 0.856 0.185 interference

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 0.122 per 1000 km.yr

frequency (UKOPA

– last 5 yrs.)

Adjusted failure 0.122 x 0.962

frequency for 20” = 0.118 per 1000 km.yr (1.18 x 10-4

per km.yr) IOCL Oil Pipeline



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.



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 widerinterest 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.

Risk

to Risk to

Personnel Publi

c

Intolerable Risk

10

-3 per year

10-4

per year

Risk Tolerable

If ALARP

10

-6 per year 10

-6 per year

Broadly

Acceptable

FIGURE-3.8 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 3.9.

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.



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 Failure Scenario Fraction Total Failure

Description of Total Rate

Failure (per km.year)

White Oil Small leak: 5 mm dia 60% 1.18 E-04

Pipeline Medium leak: 25 mm dia 25%

(20”) Large leak: 100 mm dia 10%

Full bore leak 5%

Black Oil Small leak: 5 mm dia 60% 1.25 E-04

Pipeline Medium leak: 25 mm dia 25%

(14”) Large leak: 100 mm dia 10%

Full bore leak 5%

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.



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.



FIGURE 4.1: ANNUAL WIND ROSE DIAGRAM – IMD, CHENNAI

(MINAMBAKKAM)



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 Observed Effect (kW/m2)

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

bar(g) psig Observed Effect

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.



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.



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



FIGURE-4.3 ISO-RISK CONTOURS – ENLARGED VIEW FOR INITIAL SECTION

1.0E-08 per year



FIGURE-4.4

ISO-RISK CONTOURS – ENLARGED VIEW FOR MIDDLE SECTION 1.0E-07 per year

1.0E-08 per year



FIGURE-4.5 ISO-RISK CONTOURS – ENLARGED VIEW FOR END SECTION

1.0E-08 per year

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.



Risk to

Risk to Intolerable Risk

Public

Personnel

10-3

per year

10-4

per year

Risk Tolerable if ALARP

Max. Individual Risk to Public: 1.1 x 10

-7 per year

10-6

per year

10-6

per year

Broadly Acceptable

Risk

FIGURE-4.6 INDIVIDUAL RISK ALONG IOCL CHENNAI PIPELINE



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.



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



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 - - - -



ANNEXURE – 1

IOCL CHENNAI PIPELINE ROUTE MAP



ANNEXURE – II

CONSEQUENCE ANALYSIS RESULTS


ANNEXURE – I

IOCL CHENNAI PIPELINE ROUTE MAP

ANNEXURE – II

CONSEQUENCE ANALYSIS


1. Pipeline containing HSD

Leak size – 25 mm Weather – Wind speed 3 m/s; Stability D Intensity radii for Pool Fire

Page | 2

CONSEQUENCE ANALYSIS Pool Fire on Map

Page | 3


Page | 4


2. Pipeline containing MS

Leak size – 25 mm Weather – Wind speed 3 m/s; Stability D Intensity radii for Pool Fire

Page | 5

CONSEQUENCE ANALYSIS Pool Fire on Map

Page | 6


Page | 7

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