RAPID RISK ASSESSMENT STUDY FOR RE-ROUTING OF OIL PRODUCT PIPELINES IN CHENNAI

Transcription

1 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 env@vimta.com, (NABET & QCI Accredited, NABL Accredited and ISO Certified Laboratory, Recognized by MoEF, New Delhi) May 2015

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 rerouting project in North Chennai. VIMTA Labs Limited, Hyderabad 2

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 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: 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.) 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. VIMTA Labs Limited, Hyderabad 3

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, CO 2 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. VIMTA Labs Limited, Hyderabad 4

5 3.0 SCOPE, OBJECTIVE & METHODOLOGY 3.1. Scope The scope of this RRA study covers the three underground pipelines (20, 14 and ) 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. VIMTA Labs Limited, Hyderabad 5

6 3.3.1 Consequence Analysis FIGURE-3.1 FLOW DIAGRAM OF RAPID RISK ASSESSMENT (RRA) 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. VIMTA Labs Limited, Hyderabad 6

7 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) 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 The overall failure frequency over the period 1962 to 2012 is incidents per 1000 Km/year. (Ref. UKOPA Report No UKOPA/13/0047 issued December 2013). The failure frequency over the last 20 years is incidents per 1000 km. year. For the last 5 years the failure frequency is incidents per 1000 km. year, whilst in the previous report this figure was 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 VIMTA Labs Limited, Hyderabad 7

8 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 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 VIMTA Labs Limited, Hyderabad 8

9 The overall incident frequency by hole size over the period 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 mm Full Bore* mm 110mm mm 40mm mm 20mm mm Unknown Total VIMTA Labs Limited, Hyderabad 9

10 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 VIMTA Labs Limited, Hyderabad 10

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 VIMTA Labs Limited, Hyderabad 11

12 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 inches km.yr Incidents Frequency/1000km.yr Total VIMTA Labs Limited, Hyderabad 12

13 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 Thickness Incidents km.yr mm Frequency /1000 km.yr < > Total VIMTA Labs Limited, Hyderabad 13

14 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 Suburban Urban Total VIMTA Labs Limited, Hyderabad 14

15 External Corrosion by Wall Thickness Class Figure: Products Loss Incidents by External Corrosion - Wall Thickness Class Table: Exposure by Wall Thickness Class Wall Thickness Frequency/ Exposure km. yr Incidents mm 1000 km. yr < > Total VIMTA Labs Limited, Hyderabad 15

16 External Corrosion by External Coating Type Figure: Products Loss Incidents by External Corrosion Coating Type Table: Exposure by External Coating Type External Exposure Incidents Coating km.yr Frequency / 1000 km.yr Bitumen Coal Tar Polyethylene FBE Other/Unknown Total VIMTA Labs Limited, Hyderabad 16

17 External Corrosion by Type of Backfill Figure: Products Loss Incidents by External Corrosion Backfill Type VIMTA Labs Limited, Hyderabad 17

18 Estimating IOCL Pipeline Failure Frequency The overall failure frequency reported in UKOPA database is incidents per 1000 km. year over the period 1962 to 2011, and 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 Operating Pressure Area Classification : 14 inches : 7 bar : Rural S. No. Table: Failure Frequency Adjustment Factors for 14 IOCL Oil Pipeline Adjustment Factors for Pipeline Failure Frequency Parameter Actual Ratio: Actual Value value/ Database Value Adjustment factor 1.0 External Interference 1.1 Diameter class 14 inches / Wall thickness class 7.1 mm / Area classification Rural / Avg. factor for external interference 2.0 External Corrosion 2.1 Wall thickness class 7.1 mm / Coating type 3 LPE 0.050/ Backfill type Year of Construction Avg. factor for external corrosion 3.0 Internal corrosion Pipe defect Girth weld defect Seam weld defect Ground movement 1.0 VIMTA Labs Limited, Hyderabad 18

19 S. No. Table: Adjusted Failure Frequency for 14 IOCL Oil Pipeline Adjusted Pipeline Failure Frequency for Pipeline Cause Incidents in UKOPA Data Adjustment base (Ref: Table 6) factor for No. of Fraction 14 IOCL Incidents Oil Pipeline Adjusted Factor for 14 IOCL Oil Pipeline 1. External interference External corrosion Internal corrosion Pipe defect Girth weld defect Seam weld defect Others Unknown Ground Movement Total Incidents Base failure per 1000 km.yr frequency (UKOPA last 5 yrs.) Adjusted failure frequency for x = per 1000 km.yr (1.25 x 10-4 per km.yr) IOCL Oil Pipeline VIMTA Labs Limited, Hyderabad 19

20 Pipeline size Operating Pressure Area Classification :20 inches : 7 bar : Rural S. No. Table: Failure Frequency Adjustment Factors for 20 IOCL Oil Pipeline Adjustment Factors for Pipeline Failure Frequency Parameter Actual Ratio: Actual Value value/ Database Value Adjustment factor 1.0 External Interference 1.1 Diameter class 14 inches / Wall thickness class 7.1 mm / Area classification Rural / Avg. factor for external interference 2.0 External Corrosion 2.1 Wall thickness class 7.1 mm / Coating type 3 LPE 0.050/ Backfill type Year of Construction Avg. factor for external corrosion 3.0 Internal corrosion Pipe defect Girth weld defect Seam weld defect Ground movement 1.0 VIMTA Labs Limited, Hyderabad 20

21 S. No. 1. Table: Adjusted Failure Frequency for 20 IOCL Oil Pipeline Adjusted Pipeline Failure Frequency for Pipeline Cause Incidents in UKOPA Data Adjustment base (Ref: Table 6) factor for No. of Fraction 20 IOCL Incidents Oil Pipeline External interference Adjusted Factor for 20 IOCL Oil Pipeline External corrosion Internal corrosion Pipe defect Girth weld defect Seam weld defect Others Unknown Ground Movement Total Incidents Base failure per 1000 km.yr frequency (UKOPA last 5 yrs.) Adjusted failure frequency for 20 IOCL Oil Pipeline x = per 1000 km.yr (1.18 x 10-4 per km.yr) VIMTA Labs Limited, Hyderabad 21

22 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 Risk Tolerability Criteria FIGURE-3.7 ISO-RISK CONTOURS ON SITE PLAN (TYPICAL) 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. VIMTA Labs Limited, Hyderabad 22

23 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. Risk to Personnel Risk to Public 10-3 per year Intolerable Risk 10-4 per year Risk Tolerable If ALARP 10-6 per year 10-6 per year Broadly Acceptable FIGURE-3.8 INDIVIDUAL RISK CRITERIA VIMTA Labs Limited, Hyderabad 23

24 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 Risk Assessment Figure 3.9: Societal Risk Criteria 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. VIMTA Labs Limited, Hyderabad 24

25 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 White Oil Pipeline (20 ) Black Oil Pipeline (14 ) Failure Scenario Small leak: 5 mm dia Medium leak: 25 mm dia Large leak: 100 mm dia Full bore leak Small leak: 5 mm dia Medium leak: 25 mm dia Large leak: 100 mm dia Full bore leak Fraction of Total Failure 60% 25% 10% 5% 60% 25% 10% 5% Total Failure Rate (per km.year) 1.18 E E Population Data The population across pipeline route is as shown in Table 4.2. TABLE 4.2 Population Data IOCL North Chennai Pipeline Route 4.3 Ignition Source Data Area Population 0 3 km 8.50 lakhs 3 7 km lakhs 7 10 km 9.81 lakhs 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. VIMTA Labs Limited, Hyderabad 25

26 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 ( 0 C) Rainfall (mm) Max. Min. Monthly Total January February March April May June July August September October November December 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. VIMTA Labs Limited, Hyderabad 26

27 FIGURE 4.1: ANNUAL WIND ROSE DIAGRAM IMD, CHENNAI (MINAMBAKKAM) VIMTA Labs Limited, Hyderabad 27

28 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/m 2 ) 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 Minimum energy required for piloted ignition of wood, melting of plastic tubing 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 Safe distance (no serious damage below this value); some damage to house ceilings; 10% of window glass broken Repairable damage; partial demolition of houses, made uninhabitable; steel frame of clad building slightly distorted Partial collapse of walls of houses Heavy machines (3000 lb) in industrial buildings suffered little damage; steel frame building distorted and pulled away from foundations. VIMTA Labs Limited, Hyderabad 28

29 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/m KW/m kw/m Vapour cloud explosion overpressure bar (0.3 psi) bar (1 psi) bar (3psi) - Product: HSD Leak Size: 25 mm Pool fire heat radiation intensity 4 kw/m KW/m kw/m Vapour cloud explosion overpressure bar (0.3 psi) bar (1 psi) 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. VIMTA Labs Limited, Hyderabad 29

30 4.6 RRA Results Individual risk Iso-risk contours for individual risk along pipeline route near populated areas are shown in the following Figure and 4.5. FIGURE-4.2 ISO-RISK CONTOURS FOR INDIVIDUAL RISK OVERALL ROUTE 1.0E-08 per year VIMTA Labs Limited, Hyderabad 30

31 FIGURE-4.3 ISO-RISK CONTOURS ENLARGED VIEW FOR INITIAL SECTION 1.0E-08 per year VIMTA Labs Limited, Hyderabad 31

32 FIGURE-4.4 ISO-RISK CONTOURS ENLARGED VIEW FOR MIDDLE SECTION 1.0E-07 per year 1.0E-08 per year VIMTA Labs Limited, Hyderabad 32

33 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. VIMTA Labs Limited, Hyderabad 33

34 Risk to Personnel 10-3 per year Intolerable Risk Risk to Public 10-4 per year 10-6 per year Risk Tolerable if ALARP Broadly Acceptable Risk Max. Individual Risk to Public: 1.1 x 10-7 per year 10-6 per year FIGURE-4.6 INDIVIDUAL RISK ALONG IOCL CHENNAI PIPELINE VIMTA Labs Limited, Hyderabad 34

35 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. VIMTA Labs Limited, Hyderabad 35

36 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 VIMTA Labs Limited, Hyderabad 36

37 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 VIMTA Labs Limited, Hyderabad 37

38 ANNEXURE 1 IOCL CHENNAI PIPELINE ROUTE MAP VIMTA Labs Limited, Hyderabad 38

39 ANNEXURE II CONSEQUENCE ANALYSIS RESULTS VIMTA Labs Limited, Hyderabad 39

40 ANNEXURE I IOCL CHENNAI PIPELINE ROUTE MAP

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43 ANNEXURE II CONSEQUENCE ANALYSIS

44 1. Pipeline containing HSD Leak size 25 mm Weather Wind speed 3 m/s; Stability D Intensity radii for Pool Fire CONSEQUENCE ANALYSIS Page 2

45 Pool Fire on Map CONSEQUENCE ANALYSIS Page 3

46 CONSEQUENCE ANALYSIS Page 4

47 CONSEQUENCE ANALYSIS 2. Pipeline containing MS Leak size 25 mm Weather Wind speed 3 m/s; Stability D Intensity radii for Pool Fire Page 5

48 Pool Fire on Map CONSEQUENCE ANALYSIS Page 6

49 CONSEQUENCE ANALYSIS Page 7