RAPID RISK ASSESSMENT STUDY FOR RE-ROUTING OF ......142 IDA, Phase-II, Cherlapally Hyderabad–500...

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.



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.



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

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.



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



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

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



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



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



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



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



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.

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


2.2 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



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)



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


1.3 Area classification Rural 0.040 / 0.049 0.816

Avg. factor for

external

interference

0.856

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

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



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)



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.



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



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

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.



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

(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.



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-08 per year

1.0E-07 per year



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



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



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

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


Page | 3

Pool Fire on Map


Page | 4


Page | 5

2. Pipeline containing MS

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


Page | 6

Pool Fire on Map


Page | 7

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