NNPC GAS INFRASTRUCTURE COMPANY LIMITED
ENGINEERING, PROCUREMENT & CONSTRUCTION OF
PIPELINE INFRASTRUCTURE FOR ESCRAVOS ENVIRONS
POWER SUPPLY PROJECT (EEPSP - LOT 3)
QUANTITATIVE RISK ASSESSMENT
REPORT
DOCUMENT NO.:
NGIC-EEPSP_YNL-TSF-RPT-007
R01
13/06/2023
Issued for Review
J.L.
A.A.
REV.
DATE
DESCRIPTION
BY
CHECKED
Project
Code
Client
Contractor
Discipline
Doc. Type
NGIC
EEPSP
YNL
TSF
RPT
Doc. Control No.
A.U.
NGIC
APPROVED
SequenceRev.
Number
007
This document contains information, which is for company use only. This information is to be held in confidence. Disclosure, reproduction,
or other use of this document is prohibited without the prior written consent of CLIENT
R01
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
NGIC-EEPSP_YNL-TSF-RPT-007
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Revision No: R01
REVISION HISTORY
Revision
Date
Description
R01
11/06/2023
Issued for Review
Quantitative Risk Assessment Report
Remarks
Page 2 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
NGIC-EEPSP_YNL-TSF-RPT-007
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Revision No: R01
EXECUTIVE SUMMARY
This report presents the Quantitative Risk Assessment (QRA) conducted for EEPSP - LOT 3 project.
It provides input to the Overall Design Safety Assessment for the EEPSP - LOT 3 project. The QRA
quantifies the risk associated with Major Accident Event (MAEs) that have been assessed as having
the potential to result in fatality.
In quantifying the risk, the analysis has drawn upon the results and conclusions given in the various
support studies, namely:
•
Process Hazard Analysis (PHA).
•
Fire and Explosion Risk Assessment (FERA).
The overall objective of this Quantitative Risk Assessment is to provide assurance that EEPSP - LOT
3 project is designed with relevant engineering safeguards and the residual risk levels from the pipeline
to the facility will be within acceptable guidelines.
These assessments provide a numerical estimate of the residual safety risks during the operational
phase associated with hydrocarbon gas releases from the facility in terms of:
•
Individual risk.
•
Societal risk.
The study approach adopted internationally accepted risk analysis approach, covering the following
methodology:
•
Step 1: Identification of major accident event
•
Step 2: Modelling of potential consequences including fire and explosion
•
Step 3: Calculation of frequency of hazardous event outcomes
•
Step 4: Calculation of risk levels
•
Step 5: Mitigation or reduction of risk study results with acceptable risk guidelines
Potential Hazard Incidents identified covered the pipeline through to the facility. These include releases
from various flammable gas streams, followed by jet fire, flash fire, and/or flammable gas dispersion.
Comparing the Individual risk of major areas of concerns within the facility, it was observed that the
risk was within the acceptable region while no societal risk was observed seeing that the risk contour
did not reach any nearby community.
Thus, posing no societal threat to the nearby community and thereby requiring no additional risk
reduction measure as inherent risk are adjudge to be ALARP.
Table of Contents
Quantitative Risk Assessment Report
Page 3 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
EXECUTIVE SUMMARY .................................................................................................................... 3
TABLE OF FIGURES ......................................................................................................................... 6
LIST OF TABLES............................................................................................................................... 7
ABBREVIATIONS .............................................................................................................................. 8
1.0
INTRODUCTION...................................................................................................................... 9
1.1
PROJECT DESCRIPTION ................................................................................................... 9
1.2
PROJECT OBJECTIVE ........................................................................................................ 9
1.3
PURPOSE ............................................................................................................................ 9
1.4
SCOPE ................................................................................................................................. 9
1.5
STUDY LIMITATION .......................................................................................................... 10
1.6
REFERENCES ................................................................................................................... 10
2.0
CODES AND STANDARDS .................................................................................................. 11
2.1
GENERAL .......................................................................................................................... 11
2.2
NATIONAL REGULATIONS ............................................................................................... 11
2.3
INTERNATIONAL CODES AND STANDARDS .................................................................. 11
3.0
EEPSP LOT 3 PROCESS DESCRIPTION............................................................................. 13
3.1
GENERAL .......................................................................................................................... 13
3.2
INLET FACILITY PIPING .................................................................................................... 13
4.0
QRA METHODOLOGY .......................................................................................................... 18
4.1
DATA SOURCE ASSUMPTION ......................................................................................... 19
4.2
MANNING DATA ................................................................................................................ 20
4.3
METEROLOGICAL DATA .................................................................................................. 20
4.4
FEED SOURCE AND INVENTORY ANALYSIS ................................................................. 21
5.0
HAZARD IDENTIFICATION .................................................................................................. 22
5.1
HOLE SIZE......................................................................................................................... 25
5.2
FAILURE CASE SELECTION............................................................................................. 26
6.0
FAILURE FREQUENCY ANALYSIS ..................................................................................... 27
6.1
PART COUNT ANALYSIS .................................................................................................. 27
6.2
EVENT TREE FREQUENCY .............................................................................................. 29
6.2.1
Ignition and Early Ignition ............................................................................................ 29
6.2.2
Explosion ..................................................................................................................... 29
6.2.3
Outcome Consequences ............................................................................................. 30
6.2.4
Immediate Fires ........................................................................................................... 30
6.2.5
Delayed Fires .............................................................................................................. 30
7.0
CONSEQUENCE ANALYSIS ................................................................................................ 31
7.1
SOURCE TERM MODELLING ........................................................................................... 31
7.2
PHYSICAL EFFECTS MODELLING ................................................................................... 32
Quantitative Risk Assessment Report
Page 4 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
7.2.1
Jet Fires ...................................................................................................................... 32
7.2.2
Pool Fires .................................................................................................................... 32
7.2.3
Flash Fires................................................................................................................... 32
7.2.4
Fireballs ....................................................................................................................... 33
7.2.5
Gas Explosions ........................................................................................................... 33
7.3
8.0
SUMMARY OF CONSEQUENCE AND EVENT FREQUENCY RESULTS ......................... 33
RISK ACCEPTANCE CRITERIA ........................................................................................... 34
8.1
RISK ASSESSMENT FRAMEWORK ................................................................................. 34
8.2
INDIVIDUAL RISK CRITERIA............................................................................................. 35
8.3
SOCIETAL RISK CRITERIA ............................................................................................... 36
9.0
RISK ASSESSMENT AND RESULTS ................................................................................... 37
9.1
GENERAL .......................................................................................................................... 37
9.2
INDIVIDUAL RISK PER ANNUM (IRPA) ............................................................................ 37
9.3
POTENTIAL LOSS OF LIFE (PLL) ..................................................................................... 38
10.0
CONCLUSIONS AND RECOMMENDATION ........................................................................ 40
10.1
CONCLUSION.................................................................................................................... 40
10.2
RECOMMENDATION ......................................................................................................... 40
APPENDIX A:
ASSUMPTION SHEET ..................................................................................... 41
APPENDIX B:
PLOT PLAN ........................................................................................................ 60
APPENDIX C:
ISOLATABLE SECTIONS .................................................................................. 62
APPENDIX D:
MARKED DRAWINGS OF ISOLATABLE SECTIONS..................................... 68
APPENDIX E:
EVENT TREE ................................................................................................... 88
APPENDIX F:
CONSEQUENCE MODELLING RESULTS ...................................................... 95
Quantitative Risk Assessment Report
Page 5 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
Table of Figures
Figure 1: Quantitative Risk Assessment Methodology ...................................................................... 19
Figure 2: Part Count and Leak distribution ........................................................................................ 28
Figure 3: Consequence modelling for an Event which involves Ignition ............................................ 31
Figure 4: ALARP Framework for Risk Criteria ................................................................................... 35
Figure 5: EEPSP Wind rose .............................................................................................................. 41
Figure 6: Part Count ......................................................................................................................... 49
Figure 7: Event Tree ......................................................................................................................... 52
Quantitative Risk Assessment Report
Page 6 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
List of Tables
Table 1: Reference Documents ........................................................................................................ 10
Table 2: List of NUPRC (Formerly DPR Regulations) ....................................................................... 11
Table 3: List of International Codes and Standards........................................................................... 11
Table 4: List of International Codes and Standards........................................................................... 20
Table 5: Status of HAZID Recommendations.................................................................................... 22
Table 6: HAZID Recommendations Summary .................................................................................. 23
Table 7: Representative Leak Sizes for QRA .................................................................................... 25
Table 8: Individual Risk Per Annum (IRPA) for EEPSP facility .......................................................... 38
Table 9: PPL for EEPSP facility ........................................................................................................ 38
Table 10: Wind rose Data – True North ............................................................................................ 42
Table 11: Feed gas Composition ...................................................................................................... 43
Table 12: Consequence Modelling Assumptions .............................................................................. 45
Table 13: Manning Distribution for QRA............................................................................................ 59
Quantitative Risk Assessment Report
Page 7 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
ABBREVIATIONS
ABBREVIATION
MEANING
API
American Petroleum Institute
ALARP
As Low As Reasonably Practicable
ASME
American Society Of Mechanical Engineers
BS
British Standard
CA
Condensate Accumulator
CNL-EGP
Chevron Escravos Gas Plant
EEPSP
Escravos Environs Power Supply Project
ESD
Emergency Shutdown
EPC
Engineering Procurement Construction
ESD
Emergency Shutdown
FB
Full Bore
FERA
Fire and Explosion Risk Assessment
FC
Failure Case
HAZID
Hazard Identification
HC
Hydrocarbon
LFL
Lower Flammability Limit
LoPC
Loss of Primary Containment
MAH
Major Accident Hazard
NNPC
Nigerian National Petroleum Company Limited
NPSC
Nigerian Pipelines and Storage Company
PHAST
Process Hazard Analysis Software Tool
RoW
Right of Way
QRA
Quantitative Risk Assessment
TSC
Technical Safety Control
UFL
Upper Flammability Limit
WBH
Water Bath Heater
Quantitative Risk Assessment Report
Page 8 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
NGIC-EEPSP_YNL-TSF-RPT-007
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
1.0
INTRODUCTION
1.1
PROJECT DESCRIPTION
Revision No: R01
The Nigerian National Petroleum Company Limited (NNPC) through its Subsidiary NNPC Gas
Infrastructure Company Limited (NGIC) Limited intends to construct 6" x 8km and 4” x 2km gas
pipelines that will transport lean gas from Chevron Escravos Gas Plant (CNL-EGP) and NPSC Utility
pipelines respectively to EEPSP Plant within PPMC tank farm at Escravos.
To this end, Yonkys Ya-Star Nigeria Limited has been contracted to carry out the EPC works for gas
supply to the power generation Plant at NPSC tank farm.
1.2
PROJECT OBJECTIVE
The primary objective of the project is to supply gas through a tie-in at the 16” pipeline using the existing
valve connection, and constructing a 6” spur line from the tie-in point. The early gas phase shall be
constructed through a 4” pipe connection on the 8” utility pipeline at NPSC Tank farm via hot tapping.
The project scope shall provide a facility for filtering/separating any liquid and debris including to heat
and reduce the gas pressure (PRMS) to 2- 4 bar, that will be further reduced by the regulator to be
provided for the gas driven generator.
1.3
PURPOSE
The main purpose of this QRA are as follows:
•
Estimating risk levels and assessing their significance. This helps decide whether or not the
risks need to be reduced.
•
Determine the characteristics of potential fire, dispersion and explosion event along with its
potential escalation with focus on major accident event.
•
Identifying the main contributors to the risk. This helps understanding of the nature of the
hazards and suggests possible targets for risk reduction measures
•
Assess the potential consequences in terms of impact on people, critical operation systems
vulnerable infrastructures including onsite asset and public facility.
•
Evaluate the effectiveness of the hazard mitigation measures and identify any risk reduction
opportunities to verify the intended design to ensure that potential major accident event are As
low as reasonably practicable (ALARP).
1.4
SCOPE
This study has assessed the consequences and likelihood of hazardous releases from new process
equipment associated with the EEPSP project in the bid to ensure that all potential major accident event
has been reduced to As low as reasonably practicable (ALARP) level.
Hence, the scope of this Quantitative Risk Assessment cover the following facilities:
•
6” x 8km pipeline from CNL facility to EEPSP Lot 3 Facility
•
4” x 2km pipeline from NPSC facility to EEPSP Lot 3 Facility
Quantitative Risk Assessment Report
Page 9 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
NGIC-EEPSP_YNL-TSF-RPT-007
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
•
1.5
Revision No: R01
Process Equipment and associated piping within EEPSP Lot 3 Facility
STUDY LIMITATION
This QRA studies did not fully access the risk associated with the 6” x 8km and 4” x 2km pipeline R.O.W
from CNL Facility and NPSC Facility due to non-availability of the Manning/Presence Philosophy along
pipeline R.O.W.
Thus, risk associated with 6” x 8km and 4” x 2km pipeline R.O.W from CNL Facility and NPSC Facility
shall be on hold.
1.6
REFERENCES
Table 1: Reference Documents
S/N
Document Number
1.
NGIC-EEPSP_YNL-PMS-BOD-001
Basis of Design
2.
NGIC-EEPSP_YNL-PRO-PHI-003
Emergency Shutdown and Depressuring Philosophy
3.
NGIC-EEPSP_YNL-PRO-RPT-002
Heat & Mass Balance Report for 7.5 MMSCFD
4.
NGIC-EEPSP_YNL-PRO-RPT-003
5.
NGIC-EEPSP_YNL-PRO-PFD-001
6.
NGIC-EEPSP_YNL-PRO-PFD-003
7.
NGIC-EEPSP_YNL-PRO-PID-002
8.
NGIC-EEPSP_YNL-PRO-PID-003
9.
NGIC-EEPSP_YNL-PIP-DRW-001
10.
NGIC-EEPSP_YNL-PIP-PLN-001
11.
NGIC-EEPSP_YNL-PIP-DRW-002
Plant 3D Model
12.
NGIC-EEPSP_YNL-TSF-RPT-008
Fire & Explosion Risk Assessment Report
13.
NGIC-EEPSP_YNL-TSF-RPT-009
Emergency Escape & Rescue Assessment Report
Quantitative Risk Assessment Report
Title
Heat & Mass Balance Report for 10 MMSCFD
PFD for PRMS for 10MMSCFD
PFD for PRMS for 7.5MMSCFD
P&IDs for PRMS for 10MMSCFD
P&IDs for PRMS for 7.5MMSCFD
Piping Isometrics
Overall Piping Plot Plan
Page 10 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
NGIC-EEPSP_YNL-TSF-RPT-007
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
2.0
CODES AND STANDARDS
2.1
GENERAL
Revision No: R01
All standards, codes and regulations to which this document is based, shall be the latest revision.
There are prescribed legal requirements or regulations for regulatory approval of design of safeguards
by NUPRC (Formerly DPR), as part of the overall compliance management for projects. This QRA shall
form part of the overall project risk management process which is required to be submitted as part of
the facility Safety (Case) Report.
2.2
NATIONAL REGULATIONS
Table 2: List of NUPRC (Formerly DPR Regulations)
Document No.
Document Title
DPR Guide 0032 - 2020
Guidelines for Compliance with the Technical Safety Control (TSC)
Requirements for Facility Development Projects and Modifications, August
2020
DPR Guide 0027 - 2021
Guidelines and Procedures for the Design, Construction, Operation and
Maintenance of Oil and Gas Pipeline Systems in Nigeria - 2021.
Guidelines Concerning Implementation and Use of Risk Based Inspections
DPR
in the Nigerian Petroleum Industry, 2006
2.3
INTERNATIONAL CODES AND STANDARDS
Table 3: List of International Codes and Standards
Document No.
Document Title
CMPT
A Guide to Quantitative Risk Assessment for Offshore Installations,
Publication 99/100a, 1999.
IOGP 434-1
Analyze Frequencies of Releases from Process Equipment, IOGP Report No.
IOGP 434-1, September 2019.
IOGP 434-6.1
Risk Assessment Data Directory: Ignition Probabilities; IOGP Report No. 4346.1, March 2010
IOGP 434-3
Study Frequencies of Releases from a Variety of Storage Types; IOGP
Report No. 434-3
Quantitative Risk Assessment Report
Page 11 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
NGIC-EEPSP_YNL-TSF-RPT-007
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Revision No: R01
Document No.
Document Title
IOGP 434-15
Risk Assessment Data Directory: Vulnerability of Plant / Structure; IOGP
Report No 434-15
Design and Installation of Pressure-Relieving Systems in Refineries, Part I
API STD-520
and II
API ST521
Pressure-relieving and Depressuring Systems
API RP-521
Guide for Pressure-Relieving and De-pressuring Systems
ISO 17776-2002
Guidelines on tools and techniques for hazard identification and risk
assessment, 2002
UK HSE HSL/2005/58 Review of Hazard Identification Techniques, 2005
NFPA 921
Guide for Fire and Explosion Investigation
EI 19
Fire Precautions at Petroleum Refineries and Bulk Storage Installations
Quantitative Risk Assessment Report
Page 12 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
3.0
EEPSP LOT 3 PROCESS DESCRIPTION
3.1
GENERAL
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
The EEPSP Lot 3 Facility operation has been divided into two phase’s namely: Early gas and
Permanent gas Phase.
For the Early gas phase operation, the lean gas supplied to the PRMS is sourced from the 8” utility gas
pipeline within NPSC facility. The pipeline operates at a pressure between 12 barg to 30 barg and
temperature between 20 C
̊ to 30 C
̊ .
While after Power plant commissioning, the gas supply shall be via a 6” pipeline originated from the
24” NGIC gas transmission pipeline via hot tap and from 16” pipeline through calve connection.
3.2
INLET FACILITY PIPING
3.2.1
Inlet Facility Piping for 7.5 MMSCFD
The gas enters the facility with a maximum pressure of 30 barg and temperature of 30 C
̊ . The inlet
Facility system consists of 4” pipeline from tie-in point at the existing 8” utility line within NPSC facility.
The line is fitted with an Emergency shutdown valve (31-SDV-001A) which is controlled by a
Pneumatic (gas) actuating system via a solenoid valve. Closing of shutdown valve (31-SDV-001A) shall
initiated an ESD and OSD1 action.
The line is also equipped with Pressure transmitter alarm high and low (31-PIA-001A) set at 32 barg
and 5 barg respectively. The line is also equipped with a pressure high-high and low-low trip (31PZA- 002) set at 35 barg and 4 barg respectively which trigger OSD 1 action (Facility Shutdown).
The inlet facility line is also furnished with a Temperature Alarm high and low (31-TIA-001A) set at
40 ̊C and 15 C
̊ respectively. In the event of fire, ESD is initiated and closes shutdown valve (31-SDV001A).
3.2.2
Inlet Facility Piping for 10 MMSCFD
The gas enters the facility with a maximum pressure of 85 barg and temperature of 42 C
̊ . The inlet
facility system consists of 6” pipeline from the Pig Launcher within CNL facility. The line is fitted with
an emergency shutdown valve (31-SDV-001B) which is controlled by a pneumatic (gas) actuating
system via a solenoid valve. Closing of shutdown valve (31-SDV-001B) is initiated by ESD and OSD1
action.
The line is also equipped with Pressure transmitter alarm high and low (31-PIA-001B) set at 86 barg
and 60 barg respectively. The line is also equipped with a pressure high-high and low-low trip (31PZA- 002B) set at 88 barg and 58 barg respectively which trigger OSD 1 action (Facility Shutdown).
The inlet facility line is also furnished with a Temperature Alarm high and low (31-TIA-001B) set at
Quantitative Risk Assessment Report
Page 13 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
NGIC-EEPSP_YNL-TSF-RPT-007
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Revision No: R01
45 ̊C and 20 C
̊ respectively. In the event of fire, ESD is initiated and closes shutdown valve (31-SDV001B)
3.2.3
Gas Heating System For 7.5 MMSCFD And 10 MMSCFD
The gas from the filter flows to the indirect water bath heater. For each of the PRMS facility, the heating
system consists of two identical indirect water bath heaters, one in operation at any given time and one
on standby. Each heater unit is made up of the following components
•
Stack
•
Gas/Heating section
•
Burner Management System
•
Fuel gas system
•
Fan for forced air
•
Water expansion tank for water refill
•
Pressure and temperature control system
The gas enters the heaters at a temperature between 20 C
̊ to 30 C
̊ for 7.5 MMSCFD and between
26 ̊C to 42 C
̊ for the 10 MMSCFD PRMS and exits the heaters at a temperature of 41.50 C
̊ and
63.65 C
̊ for the 7.5 MMSCFD and 10 MMSCFD respectively. The gas outlet temperature from the
heaters shall be set to compensate for the J-T effect (gas temperature drops during gas pressure
reduction) and ensure acceptable gas temperature downstream the pressure reduction skid, which
should be above the hydrocarbon dew point temperature of the gas.
The indirect water bath heaters are equipped with temperature controller which keeps the
temperature of the heaters between specific ranges to be advised by the vendor. Fuel gas supplied
to gas heater burners shall be sourced from the fuel/instrument gas skid. The water bath heater is
provided with a Burner Management System, PLC Function and Temperature controllers.
The burner management system ensures safe start-up, operation and shutdown of the heaters. The
burner heats bath water to achieve required gas outlet of 41.5 C
̊ 63.65 C
̊ for the respective PRMS. A
temperature controller regulates the fuel gas and air ratio to the burner to increase and decrease the
bath temperature so as to regulate the outlet gas temperature according to the design parameters.
Pressure and temperature control sensors are provided at the inlet and outlet of each of the gas
heater
which
triggers
the
necessary
response
at
the
predetermined
set
points.
Temperature control valves (61-TCV-001 for 7.5 MMSCFD and 61-TCV-002 for 10 MMSCFD) is
installed on bypass downstream of the water bath heater to ensure that the station outlet temperature
meets export specifications (27 C
̊ ). The thermal control system (28-TICA-005) senses the outlet
temperature of the gas located on the gas export line and signals to open the temperature control
Quantitative Risk Assessment Report
Page 14 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
NGIC-EEPSP_YNL-TSF-RPT-007
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Revision No: R01
valve (61-TCV-001 and 61-TCV-002) on the heater bypass, causing cold inlet gas to mix with the
heated gas from the heater outlet, thereby regulating export gas the temperature.
3.2.4
Pressure Reduction System
The pressure reduction section of the stations consists of two parallel trains mounted on a skid. Each
has a maximum flow capacity of 7.5 MMSCFD and 10 MMSCFD. The pressure reduction skid
operates with one (1) runs while the second train remains on standby.
The primary function of the Pressure Reduction System is to reduce the incoming gas pressure to a
constant outlet pressure that has been determined by the customer.
Each run is equipped with dual pressure control valve 71-PCV-001A/71-PCV-002A, 71-PCV003A/71-PCV-004A for the 7.5 MMSCFD 71-PCV-001A/71-PCV-002A, 71-PCV-003B/71-PCV-004B
for the 10 MMSCFD (one active and fail open mode, the second one monitor and fail close mode) to
reduce the pressure from 12 - 30 barg for 7.5 MMSCFD and 68 – 85 barg for 10 MMSCFD to 2 – 4
barg.
Pressure alarm sensors, pressure safeguarding sensors, pressure relief valves. In normal
operation, the active valve will be controlling the gas pressure and the monitor valve will be set
slightly above the active valve to monitor and be ready to take over control if the active valve fails. A
failure of the active valve will drive the valve fully open hence the designation FO.
Each of the valves shall be fitted with a pneumatic position actuator that uses gas for control.
A Pressure Transducer shall be provider to convert electric signal from the Control room to pneumatic
signal to drive the valve.
Each run has isolation valves at the inlet and outlet while a Shutdown Valve (71-SDV-001A, 71SDV-002A for 7.5 MMSCFD and 71-SDV-001B, 71-SDV-002B for 10 MMSCFD) to isolate each run in
an event of emergency or operational requirement.
Pressure Sensor (71-PIA-005/007A for 7.5 MMSCFD and 71-PIA-005B/007B for 10MMSCFD with High
and Low Alarm set point of 5.0 barg and 1.8 barg respectively, initiates high and low alarm for the
operator action.
In the event of no operator action on high and low pressure alarm, the Pressure Safeguarding trip (71PZA-006A/008A for 7.5 MMSCFD and 71-PZA-006B/008B) downstream the PCV’s shall initiate an
OSD 1 to protect to protect the system from over pressure.
Relief valves (PSV-001A/002A for 7.5 MMSCFD and PSV-001B/002B for 10 MMSCFD) are provided
at each run to protect the system from over pressure due to control valve failure. Also, a means of
discharging each run from its inventory shall be provided through manual blowdown valves
Quantitative Risk Assessment Report
Page 15 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
NGIC-EEPSP_YNL-TSF-RPT-007
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
3.2.5
Revision No: R01
Gas Metering System
The purpose of the gas metering system is to meter the volume of gas consumed by the customer and
it is measured in MMSCFD. This is achieved by installing Coriolis meter to capture flow communicating
with a Flow Computer.
The metering system has two (2) runs, where one shall be active and one on standby. Each train has
isolation valves at each end.
The gas from the pressure reduction skid enters to the metering skid at the pressure between 2 – 4
barg and temperature of 27 C
̊ .
3.2.6
Instrument Gas / Fuel Gas System
The instrument gas system receives gas from four input sources from both 7.5 MMSCFD and 10
MMSCFD PRMS; the first two input sources are from the facility inlet line which is provided for black
start and the second two input sources are from upstream the pressure reduction system.
The pressure and temperature from the inlet line are between 12 barg to 85 barg and between 20 C
̊ to
42oC respectively, while during normal operation, the pressure and temperature from upstream the
pressure reduction system shall be the output conditions from the indirect water bath heaters.
From the inlet sources, the gas lines are routed to the instrument/fuel gas heater (F-45001) where
the gas is heated to a temperature of 37.11 C
̊ during cold start and bypass during normal operations.
It is then brought to the pressure control valve 45-PCV-001/002. The instrument gas leaves the
pressure control valve at a pressure of 7.0 Barg and temperature of 25°C. The gas is scrubbed from
any liquid that may have formed through the scrubbers (S-45001/S-45002). The instrument gas is
then fed to the users at the scrubber conditions through the header via the instrument gas buffer for
the
field
instruments
and
direct
connection
for
the
indirect
water
bath
heaters.
A temperature indicator and control (45-TICA-001) is provided the instrument/fuel distribution
manifold that senses the temperature of the gas, then regulates the instrument/fuel gas heater
temperature
output
to
maintain
the
required
temperature.
The conditioned gas is distributed to the fuel gas system comprising of the indirect water bath
heaters and to the instrument gas buffer which is further distributed to all the instruments within
EEPSP Lot 3 PRMS facility.
3.2.7
Outlet Facility Piping/Pipelines
The gas leaves the metering station through an 8” line which is tied into the Power Plant receiving line
at a pressure and temperature of 2 - 4 barg and 27 C
̊ respectively. The export line is equipped with
Pressure transmitter alarm high and low (28-PIA-003A and 28-PIA-003B) set at 5 barg and 1.8 barg
respectively. The custody line is furnished with an emergency shutdown valve (28-SDV-001A and 28-
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SDV-001B) which is controlled by a pneumatic (gas) actuating system and actuate upon ESD
activation.
The line is also equipped with a pressure high-high and low-low trip (28-PZA-004A and 28-PZA- 004B)
set at 5.5 barg which trigger ESD 1 action (Facility Shutdown).
The outlet facility line is also furnished with a Temperature Indicator and Control Alarm high and low
(28-TICA-005A and 28-TICA-005B) set at 27 C
̊ . This device senses the outlet temperature of the gas
located on the gas export line and signals to open the temperature control valve (61-TCV-001 and 61TCV-002) on the heater bypass, causing cold inlet gas to mix with the heated gas from the heater outlet,
thereby regulating export gas the temperature.
3.2.8
Condensate Accumulator
The condensate system is provided within the EEPSP PRMS facility and comprises of an instrument
fitted condensate vessel (V-25003). All condensates from the filter separator, instrument gas scrubbers,
vent stack, and Pig Receiver Barrel, etc. are channeled into the vessel.
The vessel operates close to atmospheric pressure. It is equipped with a pressure safety valve set at
10 barg to protect the vessel against gas blow-by and an open vent to guide against gas implosion
during condensate evacuation.
Pressure sensors (25-PIA-003) with high and low alarm set point of 5.0 barg and are below atmospheric
pressure respectively, initiate high and low alarm for operator action.
In the event of no operator action on high- and low-pressure alarm, the pressure safeguarding trip (25PZA-002) shall initiate an ESD1 to protect the system from over Pressure.
They are provided with level gauges (25-LG-002) and level transmitters (25-LIA-003) to monitor the
liquid level in the vessel.
During operation, the level indicator and control transmitters (25-LIA-003) set between 268 mm to 1072
mm to monitor the level of the liquid and activate an alarm if the liquid level is high.
3.2.9
Vent Stack
The EEPSP PRMS facility and pipelines are complemented by a vent network and a cold vent stack.
This system is designed to receive hydrocarbon discharges from pressure relief systems and blowdown
the gas during emergency shutdown with depressurization and blowdown for maintenance purposes.
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4.0
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
QRA METHODOLOGY
The QRA study was performed according to the general methodology presented in figure 1 below.
•
Hazard Identification: to determine the incident scenarios, hazards and hazardous events, their
causes and mechanisms.
•
Frequency Estimation: to determine the frequency of occurrence of identified hazardous events
and the various consequences.
•
Consequence Analysis: to determine the extent of the consequences of identified hazardous
events.
•
Risk Summation: to determine the risk levels.
•
Risk Assessment: to identify if the risk is tolerable/intolerable and to identify risk reduction or
mitigation measures and prioritise these using techniques such as risk ranking or cost-benefit
analysis.
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Figure 1: Quantitative Risk Assessment Methodology
These elements as shown in the Figure 1 above are procedure used for both information generation
and decision-making in managing the risk.
4.1
DATA SOURCE ASSUMPTION
The assumptions made for the QRA are listed in the following table and detailed in the appropriate
Assumption Sheets in Appendix A.
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Table 4: List of International Codes and Standards
Assumption Sheet
No.
4.2
Subject
001
Weather and Meteorological Data
002
Process Parameters and Stream Composition
003
Consequence Modelling Assumptions
004
Isolatable Inventories Approach
005
Isolatable Inventories Approach
006
Failure Frequencies
007
Event Trees
008
Hazardous Event Modelling (Hole Size)
009
Consequence End point
010
Risk Tolerability Criteria
011
Manning Level and Distribution
MANNING DATA
The installation is primarily considered as an unmanned facility. The manning distribution assumptions
have a key influence on the IRPA results, as well as an impact on the societal risk results.
The total POB considered for the study is 6 persons.
The working hours are consider to be 2 x 12 hour shifts (days and night) and 26 weeks a year i.e. 2190
on-shift hours. Rotation pattern are for all crew members are considered to be 2 weeks / 2 week.
The detailed manning distribution with daily hour distribution as per areas are described in Appendix A,
Assumption Register.
4.3
METEROLOGICAL DATA
Wind statistics (strength and direction) used for the modelling have been provided in Appendix A.
Information about the wind speed stability combinations is not available, so it has been assumed that
these could be represented by F2 (Pasquill stability F-stable, wind speed 1.5m/s) and D5 (Pasquill
stability D-neutral, wind speed 5m/s). It has further been assumed that D5 occurs for 87% of the time
and F2 for the remainder. This in line with common QRA practice.
Thus, Wind speed of 5m/s (D5) shall be for this QRA.
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FEED SOURCE AND INVENTORY ANALYSIS
Material compositions and operating conditions are to be based on the worst case (e.g., rich/lean) and
worst season, if more than one is provided.
The material characterization such as pressure, temperature, composition etc. for each scenario shall
be taken from P&IDs and the M&HB.
To have more conservative approach, the condition such as maximum pressure and minimum
temperature stream in the section shall be taken into consideration.
Stream compositions will be based on those given in the H&MB sheets and shown in Appendix A.
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HAZARD IDENTIFICATION
The first stage in any risk assessment is to identify the potential incidents that could lead to the
release of a hazardous material from its normal containment and result in a major accident. This is
achieved by a systematic review of the facilities to determine where a release of a hazardous
material could occur from various parts of the installation.
In this study, only flammable hazards are relevant involving loss of containment of hydrocarbon gas.
Flammable hazards may manifest as high thermal radiation from fires and overpressures following
explosions that may cause direct damage, building collapse, etc. Flammable hazards are present
throughout the facility and associated pipelines. Fires may occur if flammable materials are released
to the atmosphere and ignition takes place.
Below shows the summary of the Hazards from the HAZID worksheet
Table 5: Status of HAZID Recommendations
Extreme Risk Hazard
High Risk Hazard
Medium Risk Hazard
Low Risk Hazard
1
19
5
2
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Table 6 below shows the general hazards that were found for loss of containment in the EEPSP project, along with possible causes, expected
consequences and proposed or inherent safeguards.
Table 6: HAZID Recommendations Summary
Category
Natural &
Environment
Hazard Cause
Lightening
Inherent Safeguard / Proposed
Recommendation
Scenario Description / Consequences
Area is lightening prone and release of lightening
energy can become ignition risk on coincident loss of •
primary containment, leading to fire/explosion
(injuries/fatalities & asset damage)
•
Natural &
Environment
Natural &
Environment
Erosion
Subsidence
Created (Manmade)
Security Hazards
Effect of
Facility on
Surrounding
Proximity to
Population
Quantitative Risk Assessment Report
Soil erosion could lead to collapsed foundation and
cracking of piping, with potential for loss of primary
containment
•
Lightening Protection System
Geo-tech & Topographical survey completed
The most up-to-date internal testing systems are
applied to discover any defects and fix them
early
Provide fit for purpose foundation and erosion
control structures
•
Check soil bearing capacity and carry out fit for
purpose foundation to manage the risk of
subsidence
Exposure to security hazard could lead to loss of •
primary containment resulting into fire and explosion
which may lead to injuries/fatalities and asset
•
damage
Facility is fenced, CCTV systems, security hut
installed
•
Carry out fire and explosion risk assessment for
the project and implement mitigation plans for
control of offsite impact
Subsidence could result into cracking of
piping/equipment and loss of primary containment
Fire and explosion from EEPSP can result to offsite
injuries/fatalities
security risk assessment
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Category
Hazard Cause
Scenario Description / Consequences
Revision No: R01
Inherent Safeguard / Proposed
Recommendation
Accidental events (seal leaks, loss of primary
Continuous Plant
•
containment from the facility) may lead to discharge
Discharges to Soil
to soil (environmental pollution)
Provide accidental oil contaminated system for
the liquid pig receiver
Emergency
Response
Absence of emergency response requirements •
(ESD/Blowdown, etc.) could escalation of major •
accident scenario (Loss of Primary containment /fire)
ESD, Blowdown incorporated in the design
Develop emergency response plan and
integrate with Lot 1 facility
Facility Hazard
Sources of Ignition
Ignition sources from EEPSP site could lead to fire
•
and explosion during loss of primary containment
scenario
Carry out hazardous area classification for the
facility and develop access control procedure
Facility Hazard
Asset Integrity
Management
Improper asset integrity management could result
•
into loss of primary containment, with escalated
consequences
Carry out HAZOP
recommendations
Tie-ins (shutdown
requirements)
Improper tie-in arrangements / operation will result to
major accident - loss of primary containment possibly
leading to injuries/fatalities, asset damage from •
ignited release and environmental pollution from
unignited release
Develop a tie-in plan
Environment
Damage
Facility Hazard
Facility Hazard
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study
and
implement
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The hazardous scenarios that become MAEs are:
•
Loss of containment of Flammable HC gas (Vapor) and resultant consequence includes;
i)
Jet fire (pressurized release)
ii) Flash fire from dispersing vapor cloud.
•
Loss of containment of Flammable HC condensate (liquid) and resultant consequence includes;
i)
Jet fire (pressurized release)
ii) Flash fire from dispersing vapor cloud.
5.1
HOLE SIZE
There is a possibility of failure associated with each mechanical component of the plant. These are
generic failures and can be caused by such mechanisms as weld failure, corrosion, vibration or
external impact (mechanical or overpressure).
The range of possible releases for a given component covers a wide spectrum, from a pinhole leak
up to a catastrophic rupture (of a vessel) or fullbore rupture (of a pipe/pipeline). It is both timeconsuming and unnecessary to consider every part of the range; instead, representative failure cases
are generated. For a given component these should represent fully both the range of possible
releases and their total frequency. The range of leak sizes considered for QRA is listed in table 7
below.
Table 7: Representative Leak Sizes for QRA
Leak Type
Representative hole Size (mm)
Small Leak
7
Medium Leak
22
Large Leak
70
Rupture
150
For each identified failure case, the appropriate data required to define that case are input to the
DNV PHAST modelling package. When the appropriate inputs are defined, PHAST calculates the
source terms of each release, such as the release rate, release velocity, release phase and drop
size. These source term parameters then become inputs to the consequence modelling.
Alternatively, PHAST allows these source terms to be input directly.
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5.2
Revision No: R01
FAILURE CASE SELECTION
Failure Case Selection stage identifies the failure cases, or major accident hazards, that will have the
potential to result in risks to personnel within the facilities and around the pipeline path, and hence
will be inputs to the risk modeling.
The Failure case for the entire EEPSP facilities has been summarized in Appendix A.
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FAILURE FREQUENCY ANALYSIS
Failure frequencies was determined for each event in order to perform a probabilistic risk
assessment. Generally, a number of techniques are available to determine such frequencies. The
approach relies on generic data. This provides failure frequencies for equipment items where data
has been obtained from failure reports from a range of facilities.
This section presents the failure frequency for the hazard scenarios identified. The failure data of
release was derived from the International Association of Oil and Gas Producers (IOGP) as detailed
in the QRA Assumption register.
6.1
PART COUNT ANALYSIS
There are a number of ways of estimating the leak frequency in a system, varying from a qualitative
approaches to complicated component failure mode analysis and failure rate data. Hence the most
preferred approach to estimate leak frequency for QRA is to count the number of main equipment
items, valves, flanges, Instruments and Length of pipe.
The number of Equipment items multiplied by their respective component leak frequency give the
overall leak frequency for the process being represented by a given isolatable section.
Thus, two key parameters are required to define the leak frequency from the system namely:
i)
Individual component leak frequency
ii)
Number of Equipment items in the system.
Hence, the Part count for the Isolatable section was given as;
Part Count = Individual component leak frequency X Number of Equipment items in the system
See Figure 2 for Part count and Leak size distribution.
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Figure 2: Part Count and Leak distribution
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6.2
Revision No: R01
EVENT TREE FREQUENCY
An Event Tree is constructed by laying out each identified contributing factor in chronological order
and assessing all possible combinations of factors to provide a number of possible hazardous event
outcomes. The lines connecting the contributing factors correspond to all the possible paths that can
occur during the development of the physical phenomenon. Each branching along the path shows
either the possibility of two different “spontaneous” outcomes or the occurrence of success or failure
in mitigation of the incident.
The Top Event on the left side of the event tree is the release of flammable hydrocarbon from the
pipeline. For each top event, the base expected frequency of occurrence has been calculated.
On the right side of the tree, the top event develops, through the subsequent branches, a number of
outcomes. The frequency of each single outcome is equal to the frequency of the top event multiplied
for the branch probabilities of all nodes along the path.
Having estimated the isolatable sections frequencies as presented in Appendix E, the range of
possible consequences that could occur after the initiating failure is developed using event tree
analysis (ETA) and the probabilities of alternative outcomes are also estimated. The event tree
shown in Appendix D was used in this study considering the following factors within the event tree:
6.2.1
i)
Ignition and early ignition probabilities; and
ii)
Explosion given ignition probability.
Ignition and Early Ignition
A fire will develop if a leak is ignited. Ignition probabilities used for event trees are based on release
rates given in Cox, Lees and Ang, as shown in Assumption Sheet 011. If the release is ignited
immediately, a jet or pool fire is assumed to develop before any mitigating measures can be taken.
However, if the leak is not immediately ignited, i.e., delayed ignition, the release may disperse to
some distance before coming in contact with an ignition source. For volatile or gaseous substance, it
will result in a flash fire or explosion if the gas accumulates in a congested area.
6.2.2
Explosion
In case of delayed ignition of flammable gas, unignited vapours may have started to accumulate in
congested areas and may result in an explosion. An explosion is defined as an ignited event that
generates sufficient overpressure to produce immediate escalation of the event. The probability of
delayed ignition leading to an explosion is based on historical data as presented by Cox, Lees and
Ang. These explosion probabilities are presented in Assumption Sheet 011.
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6.2.3
Revision No: R01
Outcome Consequences
As shown in Appendix F, the event tree outcomes are grouped together into the following event
outcomes, with the consequences of each group modelled to determine the overall risk (event tree
outcome frequency multiplied by the consequence). This section outlines the event tree outcomes for
the facility as modelled in this analysis and determined and used excel calculatiom in generating the
PLL to personnel.
6.2.4
Immediate Fires
Generally, for low-pressure liquid releases, pool fires are modelled with the fire size depending on the
inventory available to the fire, any containment (such as bunding) and drainage.
For gas releases, jet fires are typically modelled. Jet fires are directional and of high intensity. For
rupture scenarios, ignited gas releases are modelled as fireball scenarios as typically the whole
inventory of the isolatable section is discharged within seconds. For isolatable sections with only
piping, gas jet fires are modelled for rupture of the piping.
6.2.5
Delayed Fires
In the case of a delayed ignition, the ensuing flash fires flash back to the release source and
generally continue as a jet fire, depending on the hazard scenario under consideration. Equipment
and piping congestion and a lack of adequate ventilation may result in an explosion causing damage
to the surrounding area.
An event tree used for this study is shown in Appendix E.
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CONSEQUENCE ANALYSIS
Consequence analysis methodology comprises source term and physical effects modelling. Software
package DNV PHAST 8.4 has been used for the calculation of the consequence effects.
Consequence modelling has been carried out for the identified hazard scenarios, including release
rates, thermal radiation extent, dispersion and explosion overpressure distance.
Figure 3 depicts the process by which this consequence analysis was conducted. The first step is to
define the potential event sequences and potential Hazard Incident. Accidents begin with a hazard
incident, which usually results in the loss of containment of material from the process. Typical hazard
incidents might include the rupture or break of the pipeline. Once the Hazard Incident is known,
source models are selected to describe how materials are discharged from the process. The source
model provides a description of the rate of discharge.
Dispersion models convert the source term outputs to concentration fields downwind from the source.
A dispersion model is subsequently used to describe how the material is transported downwind and
dispersed to some concentration levels. For flammable releases, fire models convert the source
model information on the release into energy hazard potentials such as thermal radiation.
Figure 3: Consequence modelling for an Event which involves Ignition
7.1
SOURCE TERM MODELLING
A source term describes the flow rate in the event of a leak. The release rate was modelled using the
consequence modelling software package, DNV PHAST v8.4. Determination of the source term
would depend on the release conditions e.g., pressure, temperature, phase of release, mode of
release i.e., a hole from an equipment etc. Based on the representative hole sizes presented in
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Assumption Sheet 008, the initial release rates generated by PHAST v8.4 due to release from each
isolatable sections are presented in Appendix B
7.2
PHYSICAL EFFECTS MODELLING
The type of event outcome following a loss of containment scenario depends on many factors such
as the material, its phase, the operating conditions and the location of the release. The MAE to be
modelled are namely jet fires, pool fires, flash fires, fireballs, flammable gas dispersion, Gas
explosion. More details on the modelled outcomes are presented below.
7.2.1
Jet Fires
A jet fire describes the flame produced due to the ignition of a continuous pressurised leak or
discharge from process vessels and piping. It is a burning jet of gas or atomised liquid of defined
shape based on the momentum and dispersion of the release. This type of fire represents the most
hazardous fire attack on a vessel as it acts like a blowtorch directed at the vessel, both annealing and
eroding the metal surface of the equipment.
Jet fires may also result from releases of high-pressure liquid containing dissolved gas, due to the
gas flashing off and turning the liquid into a spray of small droplets.
7.2.2
Pool Fires
A pool fire is a burning pool of liquid that has collected on a horizontal surface. If the liquid pool
formed after a spill is ignited soon after release, the flammable atmosphere will only exist close to the
surface of the pool. The heat generated by the fire above the surface of the pool causes the
evaporation of more fuel for the fire and the fire then becomes self-sustaining. The fire will cover the
entire surface of the pool. Pool fires do not create extreme temperatures; usually resulting in
incomplete combustion and producing a smoky cloud, since the interior of the pool is starved of
oxygen. They are unlikely to cause failure of structural members but may cause failure of other
vessels that are engulfed in the fire or the 37.5 kW/m2 thermal radiation.
7.2.3
Flash Fires
A flash fire is a fire that burns back from an ignition source to its point of release origin and is of
extremely short duration lasting only a few seconds. Therefore it will not cause structural damage.
However the intensity of the thermal radiation is sufficient to result in fatalities for those engulfed in
the flash fire. After flash back, it will continue to burn as a jet fire depending on the source conditions.
The size of a flash fire is dependent on the time delay before ignition and the flammability limits of the
gas. If the gas plume is allowed to fully develop to its stoichiometric concentration before ignition, the
extent of the flash fire will be the volume of the plume that is within the flammability limits, beyond
which the gas will not ignite as its concentration is no longer flammable. Thus, the flash fire results
are presented in terms of distance to the Lower Flammability Limit (LFL) in this study.
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7.2.4
Revision No: R01
Fireballs
A fireball is an intense spherical fire resulting from a sudden release of pressurised liquid or gas that
is immediately ignited, burning as it expands, forming a ball of fire, rising in the air. A fireball expand
rapidly may cause fatalities among people within it. Fireball durations are typically 5 – 20 seconds,
and so the heat loads are unlikely to damage any equipment.
7.2.5
Gas Explosions
An explosion is the uncontrolled release of energy from a flame front propagating through a
flammable medium, characterised by the generation of heat, light and pressure; it is the pressure
generated that causes explosions to be a hazard outside the flame.
The potential for generating pressure is determined by the flame speed, defined as the rate of
propagation of the flame front. The laminar burning velocity is the velocity at which a plane
combustion wave propagates through an infinite stationary flammable mixture and is a fundamental
property of any flammable mixture. For most fuels, the maximum laminar burning velocity occurs at
fuel concentrations slightly richer than stoichiometric. The flame speed is not in general equal to the
laminar burning velocity due to the effects of the geometry of the explosion, the expansion of the
flammable mixture and gas turbulence. For each release, the extent of the vapour cloud to its LFL
level is compared against the confined areas identified on both EEPSP plot plan.
This may not be the true representation of the equipment layout in this location the 2D layout to
estimate the VBR for both locations. Those vapour clouds that extend into confined areas are
modelled for explosion given that stoichiometric fraction of the flammable gas in the confined area
may lead to an explosion.
Explosion modelling were performed with the TNO Multi-Energy model in the DNV PHAST V8.4.
7.3
SUMMARY OF CONSEQUENCE AND EVENT FREQUENCY RESULTS
The consequence and event frequency results for all the hazard scenarios identified are summarised
in Appendix F.
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8.0
Revision No: R01
RISK ACCEPTANCE CRITERIA
The risks evaluated within this study were referenced against NUPRC accepted criteria, in order to
determine the acceptability of the risks and any need for risk reduction measures to be implemented
within the design process.
The risk criteria used are drawn from the widely used framework set out by NUPRC, using the As
Low As Reasonably Practicable (ALARP) principle, and proposes risk acceptance criteria to be used
as guidance for this study.
8.1
RISK ASSESSMENT FRAMEWORK
The following measures of acceptability was evaluated in assessing the risks from any hazardous
activity:
•
Individual risk criteria was evaluated to limit risks to personnel on the facility.
•
Cost-benefit analysis was used to ensure that, once the above criteria are satisfied, an optimum
level of safety measures is chosen for the activity, taking costs as well as risks into account.
The simplest framework for risk criteria is a single risk level which divides tolerable risks from
intolerable ones. Such criteria give attractively simple results, but they need to be used very carefully,
because they do not reflect the uncertainties both in estimating risks and in assessing what is
tolerable.
A more flexible framework specifies a level, usually known as the maximum tolerable criterion, above
which the risk is regarded as intolerable whatever the benefit may be and must be reduced. Below
this level, the risks should also be made As Low As Reasonably Practicable (ALARP).
This means that when deciding whether or not to implement risk reduction measures, their cost may
be taken into account, using cost-benefit analysis. In this region, the higher the risks, the more it is
worth spending to reduce them. If the risks are low enough, it may not be worth spending anything,
and the risks are then regarded as negligible.
This approach can be interpreted as dividing risks into three tiers (as is illustrated in figure 8-1
below):
•
An upper band where risks are intolerable whatever the benefit the activity may bring. Risk
reduction measures or design changes are considered essential.
•
A middle band (or ALARP region) where the risk is considered to be tolerable only when it has
been made ALARP. This requires risk reduction measures to be implemented if they are
reasonably practicable, as evaluated by cost-benefit analysis.
•
A negligible region where the risks are negligible and no risk reduction measures are needed.
Quantitative Risk Assessment Report
Page 34 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
NGIC-EEPSP_YNL-TSF-RPT-007
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Revision No: R01
Figure 4: ALARP Framework for Risk Criteria
8.2
INDIVIDUAL RISK CRITERIA
Individual risk is widely defined as the risk of fatality (or serious injury) experienced by an individual,
noting that the acceptability of individual risks should be based on that experienced by the most
exposed (i.e. ‘worst-case’) individual. The criteria used for individual risks are the ones widely used in
the industry and approved for use by NUPRC.
These criteria are:
•
The acceptable criterion, for the public, corresponding to the level below which individual risks
can be treated as effectively negligible, is 10-6 per year (i.e., 1 in 1,000,000 years)
•
If the risk calculated from heat radiation at residential areas exceeds 5 x 10-7 per year, this will
cause injury after 30 seconds of direct exposure to the heat. The risk of injury in this case is 5
x 10-7 (i.e. 5 injuries in 10,000,000 years), which may be considered negligible.
In terms of the acceptability of individual risks, it should be noted that:
•
Individual risks are typically presented as contours that correspond to the risk experienced by
a person continuously present, outdoors, at each location.
•
While people are unlikely to remain “continuously present, outdoors” at a given point, the
individual risk levels used to assess residential developments are modified to account for 30%
presence factor or the proportion of time spent outdoors. That is, it should be conservatively
assumed that dwellings are occupied at 70% times.
Quantitative Risk Assessment Report
Page 35 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
•
8.3
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
It should also be noted that lower criteria are often adopted with respect to vulnerable
populations, such that schools and hospitals, for example, should be located such that the
individual risks are well below 10-6 per year.
SOCIETAL RISK CRITERIA
A proposed criterion for Societal Risk is set out in form of an F-N curve, which gives the cumulative
frequency (F) of exceeding a number of fatalities (N).
It is, however, important to note that the risk contour did not reach the community close to facility.
Quantitative Risk Assessment Report
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NNPC GAS INFRASTRUCTURE COMPANY LIMITED
NGIC-EEPSP_YNL-TSF-RPT-007
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
9.0
RISK ASSESSMENT AND RESULTS
9.1
GENERAL
Revision No: R01
The results of the risk analysis are presented in this section. The results are expressed in terms of:
•
IRPA for onsite worker groups;
•
PLL per annum for onsite workers
Note that F-N curve for offsite societal risk was not consider since that the risk contour didn’t reach
the communities surrounding the facility, thus posing no societal risk threat.
In addition, the risk results for the EEPSP were generated from the generated event trees.
A spreadsheet was used to calculate the risks and generate a wide range of risk indicators in a
variety of formats. The objective in compiling this risk results section was to present sufficient
information to provide an understanding of the key risk drivers without reporting the entire model
output
9.2
INDIVIDUAL RISK PER ANNUM (IRPA)
A spreadsheet was also used to integrate frequencies and consequences of the various outcomes in
order to give measures of the Individual Risk (IR) level with respect as per location occupied by
onsite worker.
IRPA is the statistical likelihood of an identified individual perishes during a year of facility operation.
It is a measure of “inherent” risk and is applicable regardless of population density.
IRPA is the calculated probability of fatality per annum to a hypothetical individual who is present at
the site 24 hours a day, 365 days a year, i.e. it does not take into account the actual amount of time a
person spends at site.
IRPA is defined in Equation below as:
𝐼𝑅𝑃𝐴 = 𝐿𝑆𝐼𝑅 x
Rate of Time in Plant
Total Manhour
LSIR – Location Specific Individual Risk
LSIR is a function of the Probability of Fatality and Frequency of a hazardous event for the occupied
location in the facility.
𝐿𝑆𝐼𝑅 = Fatality level x Event frequency
Occupied location/area within the EEPSP facility is given as:
•
Station Inlet area
•
Pig Receiver area
•
Control Building
•
Gate House
Quantitative Risk Assessment Report
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NNPC GAS INFRASTRUCTURE COMPANY LIMITED
NGIC-EEPSP_YNL-TSF-RPT-007
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
•
Water Treater Area
•
Process Area 1(Filter Separator Area)
•
Process Area 2 (Water Bath Heater Area)
•
Process Area 3 (Condenser Accumulation Area)
•
Process Area 4 (PRMS /MS1)
•
Process Area 5 (PRMS /MS2)
Revision No: R01
Table 8: Individual Risk Per Annum (IRPA) for EEPSP facility
S/n
Occupied Area
LSIR
IRPA
1
Station Inlet Area
4.47E-03
3.32E-06
2
Pig Receiver Area
4.32E-03
3.22E-06
3
Control Building
0.00E+00
0.00E+00
4
Gate House
0.00E+00
0.00E+00
5
Water Treatment Plant Area
0.00E+00
0.00E+00
6
Process Area 1(Filter Separator
Area)
1.05E-02
7.85E-06
7
Process Area 2 (Water Bath Heater
Area)
1.14E-02
8.48E-06
8
Process Area 3 (Condenser
Accumulation Area)
7.98E-04
5.94E-07
9
Process Area 4 (PRMS /MS1)
2.90E-03
2.16E-06
10
Process Area 4 (PRMS /MS2)
6.72E-04
5.00E-07
9.3
POTENTIAL LOSS OF LIFE (PLL)
PPL is the calculated Individual Risk Per Annum with respect to number of onsite worker.
Table 9: PPL for EEPSP facility
S/n
Occupied Area
No of Workers
IRPA
PPL
1
Station Inlet Area
2
3.32E-06
6.65E-06
2
Pig Receiver Area
3.22E-06
6.43E-06
3
Control Building
0.00E+00
0.00E+00
Quantitative Risk Assessment Report
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NNPC GAS INFRASTRUCTURE COMPANY LIMITED
NGIC-EEPSP_YNL-TSF-RPT-007
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
No of Workers
Revision No: R01
S/n
Occupied Area
4
Process Area 1(Filter
Separator Area)
7.85E-06
Process Area 2
(Water Bath Heater
Area)
8.48E-06
Process Area 3
(Condenser
Accumulation Area)
5.94E-07
Process Area 4
(PRMS /MS1)
2.16E-06
Process Area 4
(PRMS /MS2)
5.00E-07
5
6
7
8
IRPA
PPL
1.57E-05
1.70E-05
1.19E-06
4.32E-06
1.00E-06
9
Gate House
2
0.00E+00
0.00E+00
10
Water Treatment
Plant Area
2
0.00E+00
0.00E+00
Comparing the IRPA and PPL values within the facility ie Tables 8 and 9 with the ALARP Framework,
it can be deduced that the risk are within negligible region in the ALARP triangle, hence there will no
need for any further risk reduction measures.
Quantitative Risk Assessment Report
Page 39 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
10.0
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
CONCLUSIONS AND RECOMMENDATION
Based on the findings of this QRA and the subsequent analysis completed, the following conclusions
and recommendations can be made:
10.1
CONCLUSION
The results of this QRA report show that the 1 x 10-6 risk contour (which is the risk of fatality to the
public) does not appear for the 30 years of operation of this facility since as there are no visible
dwelling around the pipeline vicinity. This pipeline operations is considered ALARP if all the initial
design assumptions are upheld.
10.2
RECOMMENDATION
i)
The emphasis on risk reduction should be on preventative measures, i.e. to minimize the
potential for leaks to occur. This would majorly be achieved through appropriate design (to
recognized standards) and through effective inspection, testing and maintenance plans /
procedures. All of these measures are already included in the pipeline design and mitigation
measures to be followed strictly by OWNER.
ii)
For isolation to be effective first requires detection to occur. Close monitoring and rapid
shutdown of the pipeline in case of an emergency are important to limiting the effects of leaks.
Quantitative Risk Assessment Report
Page 40 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
NGIC-EEPSP_YNL-TSF-RPT-007
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
APPENDIX A:
Revision No: R01
ASSUMPTION SHEET
ASSUMPTION SHEET
Project: ENGINEERING, PROCUREMENT & CONSTRUCTION OF PIPELINE INFRASTRUCTURE FOR
ESCRAVOS ENVIRONS POWER SUPPLY PROJECT (EEPSP - LOT 3)
Assumption No.: 001
Revision: 0
Date: 08/06/2023
Subject: Weather and Meteorological Data
Assumption:
Weather conditions are used in DNV PHAST (consequence modelling).
Assumptions regarding the required inputs are as follows:
•
Relative humidity of 84.66% is assumed based on the Mean Relative Humidity.
•
An ambient temperature of 30°C is assumed based on the ‘Ground Temperature.
•
The wind conditions are:
Day Time:
•
5D – Pasquill stability factor D with wind speed 5m/s; and
Night Time:
•
1.5F – Pasquill stability factor F with wind speed 1.5m/s.
Wind rose data for Escravos area will be used for the project;
Figure 5: EEPSP Wind rose
Quantitative Risk Assessment Report
Page 41 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
NGIC-EEPSP_YNL-TSF-RPT-007
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Revision No: R01
ASSUMPTION SHEET
Project: ENGINEERING, PROCUREMENT & CONSTRUCTION OF PIPELINE INFRASTRUCTURE FOR
ESCRAVOS ENVIRONS POWER SUPPLY PROJECT (EEPSP - LOT 3)
Assumption No.: 001
Revision: 0
Date: 08/06/2023
Subject: Weather and Meteorological Data
Based on the windrose data, the following wind direction data has been extracted, assumes true north.
Table 10: Wind rose Data – True North
N
NNE
NE
ENE
E
ESE
SE
0
22.5
45
67.5
90
112.5
135
5D
0.3
0
0.05
0
0.2
0
0.1
SES
S
SSW
SW
WSW
W
WNW
NW
157.5
180
202.5
225
247.5
270
292.5
315
0
0.43
0
0
0.83
0
0
0
Weather
Justification:
The weather conditions have a key influence on flammable cloud dispersion and hence the consequences
associated with any release and direct impact on consequence modelling results. The influence of any
specific weather category and direction will vary for every release. Minor changes in the meteorological
assumptions will have a negligible influence on the risk results.
References:
1. Nigerian Meteorological Data (NiMET)
2. http://www.metartaf.com/NG
Comments:
Quantitative Risk Assessment Report
Page 42 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
NGIC-EEPSP_YNL-TSF-RPT-007
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Revision No: R01
ASSUMPTION SHEET
Project: ENGINEERING, PROCUREMENT & CONSTRUCTION OF PIPELINE INFRASTRUCTURE FOR
ESCRAVOS ENVIRONS POWER SUPPLY PROJECT (EEPSP - LOT 3)
Assumption No.: 002
Revision: 0
Date: 08/06/2023
Subject: Process Parameters and Stream Composition
Assumption:
Material compositions and operating conditions are to be based on the worst case (e.g., rich/lean) and worst
season, if more than one is provided.
The material characterization such as pressure, temperature, composition etc. for each scenario shall be
taken from P&IDs and the M&HB.
To have more conservative approach, the condition such as maximum pressure and minimum temperature
stream in the section shall be taken into consideration.
Stream compositions will be based on those given in the H&MB sheets and shown in Tables 11 below
Table 11: Feed gas Composition
S/N
Component
Formula
Average Mole
1
Nitrogen
N2
0.3180
2
Methane
CH4
88.9274
3
Carbon-dioxide
CO2
2.1729
4
Ethane
C2H4
6.0411
5
Propane
C3H8
1.8150
6
i-Butane
C4H10
0.2650
7
n-Butane
C4H10
0.2283
8
i-Pentane
C5H12
0.0372
9
n-Pentane
C5H12
0.1445
10
n-Hexanes
C6H14
0.0475
11
n-Heptane
C7H16
0.0031
12
n-Octane
C8H18
0.0000
13
n-Nonane
C9H20
0.0000
Total
Quantitative Risk Assessment Report
100
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NNPC GAS INFRASTRUCTURE COMPANY LIMITED
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ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Revision No: R01
Justification:
This is a conservative approach.
The process parameters have direct impact in the gas dispersion and explosion simulations.
References:
1. NGIC-EEPSP_YNL-PRO-RPT-002 Heat & Mass Balance Report for 7.5 MMSCFD
2. NGIC-EEPSP_YNL-PRO-RPT-003 Heat & Mass Balance Report for 10 MMSCFD
3. NGIC-EEPSP_YNL-PRO-PFD-001 PFD for PRMS for 10MMSCFD
4. NGIC-EEPSP_YNL-PRO-PFD-003 PFD for PRMS for 7.5MMSCFD
5. NGIC-EEPSP_YNL-PRO-PID-002 P&IDs for PRMS for 10MMSCFD
6. NGIC-EEPSP_YNL-PRO-PID-003 P&IDs for PRMS for 7.5MMSCFD
Comments:
Quantitative Risk Assessment Report
Page 44 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
NGIC-EEPSP_YNL-TSF-RPT-007
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Revision No: R01
ASSUMPTION SHEET
Project: ENGINEERING, PROCUREMENT & CONSTRUCTION OF PIPELINE INFRASTRUCTURE FOR
ESCRAVOS ENVIRONS POWER SUPPLY PROJECT (EEPSP - LOT 3)
Assumption No.: 003
Revision: 0
Date: 08/06/2023
Subject: Consequence Modelling Assumptions
Assumption:
The following general modelling assumptions was used for the assessment.
Table 12: Consequence Modelling Assumptions
Parameter
Meteorological Data
Flammable Gas End Points
Dispersion Averaging Times
Solar Radiation
Modelling Assumptions
•
Wind speed 1.5m/s and Pasquill stability class ‘F’
•
Wind speed 5m/s and Pasquill stability class ‘D’
Distances to 1/2 LFL and UFL.
The averaging time for flammable gas dispersions will be set at 18.75s
which is the default setting in the software (Reference 4).
1.04 kW/m2 solar radiation allowance will be included in the thermal
radiation calculation for day and nighttime respectively.
A surface roughness parameter of 0.045mm is adopted for all wind
Surface Roughness
speeds and stability classes. This reflects the equivalent of open
countryside, and flat land/open farmland.
Release Orientation
A release height of 1m will be used.
Justification:
This is a conservative approach.
The process parameters have direct impact in the gas dispersion and explosion simulations.
References:
1. CMPT, A Guide to Quantitative Risk Assessment for Offshore Installations, Publication 99/100a, 1999.
2. IP- 19 IP Model Code of Safe Practice in the Petroleum Industry.
3. Methods of the Calculation of Physical Effects ‘Yellow Book' CPR 14E
Comments:
Quantitative Risk Assessment Report
Page 45 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
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EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Revision No: R01
ASSUMPTION SHEET
Project: ENGINEERING, PROCUREMENT & CONSTRUCTION OF PIPELINE INFRASTRUCTURE FOR
ESCRAVOS ENVIRONS POWER SUPPLY PROJECT (EEPSP - LOT 3)
Assumption No.: 004
Revision: 0
Date: 08/06/2023
Subject: Isolatable Inventories Approach
Assumption:
Isolatable inventories were determined from a review of the PFD and P&IDs. Isolation of streams were based
on the following:
•
Between Emergency Isolation Valves.
•
Between emergency isolation valves (ESDV or XZVs) and sectionalizing block valves.
Isolatable
Section (IS)
IS-01
FC-01
4” above ground line from NPSC Facility Tie in - station inlet header
FC-02
Instrument gas from Station inlet to Instrument gas Skid.
FC-03
Inlet Filter separator package V-25001A
FC-04
IS-02
Inlet Indirect Water Bath Heater F-61001A
FC-06
Inlet Indirect Water Bath Heater F-61001B
FC-07
Inlet Pressure Reduction Skid Package
FC-08
Inlet Pressure Reduction Skid – IGS/FS Skid
FC-10
FC-56
FC-11
FC-12
IS-04
FC-13
FC-14
FC-15
IS-05
Inlet Filter separator package V-25001B
FC-05
FC-09
IS-03
Section Description
Failure Cases
(FC) No.
FC-16
Quantitative Risk Assessment Report
Inlet metering & control package 7000-PK-002
1” PRMS line – IGS /FS
6” above ground line from CNL Facility Tie in - station inlet header
1” above ground liquid outlet of the filter separators V-25001A to closed
drain V-25002
1” above ground liquid outlet of the filter separators V-25001B to closed
drain V-25002
1/ ”
2
above ground liquid outlet of the Vent Stack 7000-FS-003 to closed
drain
1” liquid outlet of Pig Receiver PR-31001 to Condensate Accumulator V25002
1/ ”
2
liquid outlet of the Instrument Supply Vessel to Condensate
Accumulator V-25002
1” 7.5MMSCFD Station inlet line – 4” Inlet Isolation Vent header.
Page 46 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
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EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
FC-18
2” 7.5 MMSCFD Filter separator package V-25002A Pressure Relief line
to 4” Filter Separator Vent header
FC-19
2” 10 MMSCFD Filter separator package V-25002A Pressure Relief line
to 4” Filter Separator Vent header
FC-20
2”,1”, 1” 7.5 MMSCFD Filter separator package V-25002B Pressure
Relief line to 4” Filter Separator Vent header.
FC-21
2”, 1”, 1” 10 MMSCFD Filter separator package V-25002B Pressure
Relief line to 4” Filter Separator Vent header
FC-22
2”, 7.5 MMSCFD Indirect Water bath heater F-61002A Pressure Relief
line to 4” WBH Vent header.
FC-23
IS-07
Revision No: R01
2” 10 MMSCFD Indirect Water bath heater F-61002B Pressure Relief
line to 4” WBH Vent header.
FC-24
1” 7.5 MMSCFD Indirect Water bath heater F-61002A Pressure Relief
line to 4” WBH Vent header.
FC-25
1” 10MMSCFD Indirect Water bath heater F-61002B Pressure Relief
line to 4” WBH Vent header header
FC-26
3” 7.5MMSCFD PRMS Relief line to 4” PRMS Vent header
FC-27
3” 10MMSCFD PRMS Relief line to 4” PRMS Vent header
FC-28
2” 7.5 MMSCFD PRMS Blowdown line to 4” PRMS Vent header.
FC-29
2” 10 MMSCFD PRMS Blowdown line to 4” PRMS Vent header.
FC-30
1”7.5MMSCFD Gas Metering System Relief line to 2” Gas Metering
Vent header.
FC-31
1”10MMSCFD Gas Metering System Relief line to 2” Gas Metering Vent
header.
FC-32
4” Pig Launcher Relief line to 4” Pig System Vent header
FC-33
4” Pig Receiver Relief line to 4” Pig System Vent header
FC-34
4” Pipeline Vent header, 4” Metring Skid 1&2 Vent header, 4” PRMS
Skid 1&2 Vent header, 4” Indirect WBH 1&2 vent header, Inlet Isolation
vent header, 4” Pigging System Vent header to 8” Cold Vent Header
FC-35
FC-35 4” Inlet piping to Inlet Filter separator V-25002A
FC-36
1” Filter separator Relief to 4” Filter separator V-25002A Vent header
FC-37
1” Filter separator Relief to 4” Filter separator V-25002A Vent header
FC-38
4” Filter separator V-25002B outlet line to inlet header WBH F-61002B
FC-39
1” ” Filter separator V-25002B liquid outlet line to Condensate
accumulator
Quantitative Risk Assessment Report
Page 47 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
NGIC-EEPSP_YNL-TSF-RPT-007
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
IS-08
IS-09
IS-10
IS-11
IS-12
Revision No: R01
FC-40
4” Filter separator V-25002A and 4” Filter separator V-25002B outlet to
4” WBH F-61002A inlet line.
FC-41
4” WBH F-61002A outlet line to 4” WBH F-61002A Warm gas header
FC-42
1” WBH F-61002A outlet By-pass line to 4” WBH F-61002A Cold vent
header.
FC-43
1” BDV line via 4” Filter separator V-25002A and 4” Filter separator V25002B outlet to 4” WBH F-61002A Cold vent header.
FC-44
4” WBH F-61002A outlet line via 4” WBH F-61002B cold gas header to
4” WBH F-61002B inlet line.
FC-45
4” WBH F-61002B Outlet line via 4” WBH F-61002B Warm gas header
to PRMS.
FC-46
1” WBH F-61002B outlet By-pass line to 4” WBH F-61002B Cold vent
header.
FC-47
4” WBH F-61002B Warm gas header to 4” PRMS Header.
FC-48
4” PRMS Header via 2” line via to IGP/FS Skid
FC-49
6” Tie-in line to Pig launcher
FC-50
6” Pig Launcher line to 4” Facility Inlet line
FC - 51
1” Pig Receiver Relief line to 4” Pig Receiver Cold Vent Header.
FC - 52
2” Pig Receiver Kicker line to 4” Facility Inlet line
FC - 53
4” 10MMSCFD PRMS line to 8” 10MMSCFD PRMS header line
FC – 54
8” 10MMSCFD PRMS line to 8” Gas Metering System
FC - 55
8” 10MMSCFD Gas Metering System header to 8” 10MMSCFD Gas
Metering System outlet line via 8” header.
FC - 56
8” 10MMSCFD Gas Metering System outlet – EEPSP Power plant
FC- 57
4” 7.5 MMSCFD PRMS line to 8” 10MMSCFD PRMS header line
FC- 58
8” 7.5 MMSCFD PRMS line to 8” Gas Metering System
FC - 59
8” 7.5 MMSCFD Gas Metering System header to 8” 7.5 MMSCFD Gas
Metering System outlet line via 8” header.
Quantitative Risk Assessment Report
Page 48 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
NGIC-EEPSP_YNL-TSF-RPT-007
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Revision No: R01
ASSUMPTION SHEET
Project: ENGINEERING, PROCUREMENT & CONSTRUCTION OF PIPELINE INFRASTRUCTURE FOR
ESCRAVOS ENVIRONS POWER SUPPLY PROJECT (EEPSP - LOT 3)
Assumption No.: 005
Revision: 0
Date: 08/06/2023
Subject: Process Block and Equipment Part Count
Assumption:
Facility process shall be divided into process blocks representative of the process areas on the facility. Within
each process block the equipment will be split up into isolatable process sections defined by the operating
conditions of the plant and the hydrocarbon fuel components present.
For each isolatable process section, the total equipment counts will be used to calculate the total leak
frequencies. The counts in all sections will be made on the basis of major equipment items like vessels,
columns, heat exchangers including the piping.
Only equipment in service during normal operation and with the potential to release HC vapour will be taken
into account. Equipment used on an infrequent basis such as pig launchers will be excluded from the study.
For each major piece of equipment fittings count will be done using the project PFD/P&ID. The fittings count
will then be used in conjunction with the equipment information for each of the isolatable sections to give a leak
frequency per hole size for each of the isolatable sections.
To determine event frequency failures, the parts count for the flowlines/pipeline will be performed using basic
process flow diagrams. To complete the parts count, it is assumed that a flange creates potential for 2 leak
points as shown in figure below. The parts count results are provided in Table below.
The Parts Count exercise will take the following into consideration:
1. All valves have two flanges.
2. Where a flanged valve separates isolatable section, the upstream flange will be counted with the valve
only.
3. A leak is assumed from two connected flanges; viz;
Figure 6: Part Count
Quantitative Risk Assessment Report
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NNPC GAS INFRASTRUCTURE COMPANY LIMITED
NGIC-EEPSP_YNL-TSF-RPT-007
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Revision No: R01
ASSUMPTION SHEET
Project: ENGINEERING, PROCUREMENT & CONSTRUCTION OF PIPELINE INFRASTRUCTURE FOR
ESCRAVOS ENVIRONS POWER SUPPLY PROJECT (EEPSP - LOT 3)
Assumption No.: 005
Revision: 0
Date: 08/06/2023
Subject: Process Block and Equipment Part Count
Parts Description
Actuated valves
Flanges
Non-Return Valves
Pipe length
Quantitative Risk Assessment Report
Parts Count
3
8 (16 leak points)
1
50m
Page 50 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
ASSUMPTION SHEET
Project: ENGINEERING, PROCUREMENT & CONSTRUCTION OF PIPELINE INFRASTRUCTURE FOR
ESCRAVOS ENVIRONS POWER SUPPLY PROJECT (EEPSP - LOT 3)
Assumption No.: 006
Revision: 0
Date: 08/06/2023
Subject: Failure Frequencies
Assumption:
As Weam has not received a database from the Owner, hence, the generic failure data for valves, flanges,
pipeline, etc. has been used as the basis of the frequency analysis as prescribed in IOGP 434 – 01 Process
Release Frequencies.
Data from the EGIG Pipeline Incidents as well as local available and relevant online data were considered
and used for specific onshore pipeline hazards such as external interference, external corrosion and materials
defects data. The EGIG database represents a source of pipeline fault data, which is specific to the European
transmission and based on incidents occurring during over half a million pipeline operating years (of which
over 90% is natural gas pipelines) between 1970 and 2016.
The primary failure frequencies that will be used are given below.
Justification:
•
•
•
Key influence on the risks (i.e., risk is directly proportional to frequency).
CONTRACTOR assumes that frequency analysis based on Parts Count Approach was used.
CONTRACTOR considers flanges, instrument connections/ small bore fittings in release frequency
estimation.
•
CONTRACTOR considers main equipment and associated piping in release frequency estimation.
References:
IOGP, “Process Release Frequencies,” Risk Assessment Data Directory, International Association of
Oil & Gas Producers, Report No. 434‐01, September 2019;
2) EGIG: Gas Pipeline Incident - 10th Report of the European Gas Pipeline Incident Data Group (period
1970 – 2016)
3) ANSI/ASME B31.8: Gas Transmission and Distribution Piping Systems
Comments:
1)
Quantitative Risk Assessment Report
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NNPC GAS INFRASTRUCTURE COMPANY LIMITED
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EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Revision No: R01
ASSUMPTION SHEET
Project: ENGINEERING, PROCUREMENT & CONSTRUCTION OF PIPELINE INFRASTRUCTURE FOR
ESCRAVOS ENVIRONS POWER SUPPLY PROJECT (EEPSP - LOT 3)
Assumption No.: 007
Revision: 0
Date: 08/06/2023
Subject: Event Trees
Assumption:
The event tree analysis is used to estimate event outcome frequency (i.e., jet fire, flash fire, pool fire & explosion).
The type of ignition and release orientations are accounted for in event tree branches.
Event tree probabilities will include Immediate ignition, Delayed ignition and No ignition.
The generic event trees considered for gas, two-phase & liquid releases are presented in figure below.
Figure 7: Event Tree
The probability of explosion upon ignition of explosive mixture depends on its release rate and is taken from Cox, Lee
and Ang, data published the IP Research Report, as presented in Table below:
Release Rate
Probability of Explosion given
Ignition
Minor (< 1 kg/s)
0.04
Major (1 – 50 kg/s)
0.12
Massive (> 50 kg/s)
0.3
References:
Quantitative Risk Assessment Report
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NNPC GAS INFRASTRUCTURE COMPANY LIMITED
NGIC-EEPSP_YNL-TSF-RPT-007
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Revision No: R01
ASSUMPTION SHEET
Project: ENGINEERING, PROCUREMENT & CONSTRUCTION OF PIPELINE INFRASTRUCTURE FOR
ESCRAVOS ENVIRONS POWER SUPPLY PROJECT (EEPSP - LOT 3)
Assumption No.: 007
Revision: 0
Date: 08/06/2023
Subject: Event Trees
1. Energy Institute, Ignition Probability Review, Model Development and Look-Up Correlations, IP Research
Report, January 2006
2. Cox, A.W., Lees, F.P., and Ang, M.L., “Classification of Hazardous Locations”, IChemE. (1990).
Comments:
Quantitative Risk Assessment Report
Page 53 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
NGIC-EEPSP_YNL-TSF-RPT-007
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Revision No: R01
ASSUMPTION SHEET
Project: ENGINEERING, PROCUREMENT & CONSTRUCTION OF PIPELINE INFRASTRUCTURE FOR
ESCRAVOS ENVIRONS POWER SUPPLY PROJECT (EEPSP - LOT 3)
Assumption No.: 008
Revision: 0
Date: 08/06/2023
Subject: Hazardous Event Modelling (Hole Size)
Assumption:
Hole Size Distribution
The release scenarios for each hazard identified is broken down into representative hole sizes. The following
was be applied for the pipeline segments:
The following leak sizes was considered:
Release Size
Representative
Range (mm)
Release Size (mm)
Description
1–3
7
Small
10 – 50
22
Medium
50 – 150
70
Large
150
150
Full Rupture
3 – 10
Justification:
The dispersion and consequences associated with the pseudo components are relatively sensitive to
assumptions affecting the heat transfer to the cloud. Hence, the above values are relatively conservative
representative conditions, but will not necessarily correspond to the worst-case dispersion conditions that may
occur. The release size selected as representative is a key factor in the release parameters and subsequent
consequences for each case.
The assumptions have a direct impact on consequence impact assessment and escalation potential.
References:
1. IOGP, “Process Release Frequencies,” Risk Assessment Data Directory, International Association of Oil
& Gas Producers, Report No. 434‐1, March 2010;
Comments:
Quantitative Risk Assessment Report
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NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
ASSUMPTION SHEET
Project: ENGINEERING, PROCUREMENT & CONSTRUCTION OF PIPELINE INFRASTRUCTURE FOR
ESCRAVOS ENVIRONS POWER SUPPLY PROJECT (EEPSP - LOT 3)
Assumption No.: 009
Revision: 0
Date: 08/06/2023
Subject: Consequence End point
Assumption:
Based on fluid composition and conditions, the following consequence scenarios was be considered:
•
Jet fire – Jet fires was considered for all vapour inventories and for liquid streams where the
components of the stream are predominantly flammable.
•
Pool fire – Pool fires may be considered for all liquid hydrocarbon streams where the components
of the stream are predominantly flammable.
•
Vapour Cloud Explosion (VCE) – Burning gas cloud that develops high overpressures. This is likely
to kill anyone within it and may also severely damage steel structures.
•
Flash fire – A fire that propagates through a cloud of gas. This may be lethal for anyone within it but
is unlikely to damage steel structures.
The table below summarizes the consequence end-points that was used to calculate the consequences.
Consequence
Event
Parameter
Thermal Radiation
(Jet Fire, Pool Fire,
Fireball)
4.7kW/m2
Description
CMPT defines 5kW/m2 as the limiting radiation intensity for
escape action lasting more than a few minutes in normal
plant clothing.
Limiting radiation intensity for escape actions lasting a few
12.5kW/m2
seconds. At this level, the pain threshold is reached in about
4 seconds, and second degree burns on exposed skin in
about 40 seconds.
Taken as the criterion for immediate fatality. At this level, the
pain threshold is virtually instantaneous, and second degree
37.5kW/m2
burns on exposed skin occur in about 8 seconds.
This thermal radiation level is sufficient to cause damage to
process equipment after prolonged exposure.
Flammable Gas
50% LFL
The 50% LFL result is presented to account for inconsistent
gas cloud dispersion due to wind speed and stability.
Flash fire envelope. Personnel within gas cloud are engulfed
LFL
in a fire that, although brief, is likely to cause death due to
inhalation of hot combustion gases, if not due to burns.
Quantitative Risk Assessment Report
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EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
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Revision No: R01
Probability of death of 100% is assumed for people within
the cloud.
Explosion
Overpressure
Overpressure (bar)
Effects
0.02
Shattering of windows
0.13
Frame distortion of steel framed building, dangerous for
people, 1% lethality.
0.2
Steel framed building pulled out from foundation
References:
1. CMPT, A Guide to Quantitative Risk Assessment for Offshore Installations, Publication 99/100a, 1999.
Comments:
Quantitative Risk Assessment Report
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ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Revision No: R01
ASSUMPTION SHEET
Project: ENGINEERING, PROCUREMENT & CONSTRUCTION OF PIPELINE INFRASTRUCTURE FOR
ESCRAVOS ENVIRONS POWER SUPPLY PROJECT (EEPSP - LOT 3)
Assumption No.: 010
Revision: 0
Date: 08/06/2023
Subject: Risk Tolerability Criteria
Assumption:
Individual Risk Calculations
The risk results will be presented as individual risk.
The UK Institution of Chemical Engineers (1992) defines risk as ‘the frequency at which an individual may be
expected to sustain a level of harm from the realization of specified hazards’. It is usually taken to be the risk
of death and expressed as a risk per year. The most common example of individual risk is the iso-risk contour.
This allows for major hazard areas to be easily identified and the effects on specific vulnerable locations to be
more easily observed.
A determination of individual risks to the public, and to employees, forms the basis for risk-decision making. It
provides an overall assessment of the level of risk to the exposed population and highlights the major
contributors to the risk. Individual risk assessment combines the results of the consequence modelling, with a
detailed assessment of frequencies, utilizing failure frequency data.
The following risk criteria are used by the NNPC to assess the individual risk exposed to employees, contractors
as well as public people:
•
Maximum tolerable risk for workers 1E-03 per year
•
Maximum tolerable risk for the public 1E-04 per year
•
Broadly acceptable risk 1E-06 per year
In between the maximum tolerable and broadly acceptable levels, NNPC requires that risk be reduced to a
level which is As Low As Reasonably Practicable (ALARP), taking account of the costs and benefits of any
further risk reduction. Near to the broadly acceptable criterion, the risks are considered tolerable if the cost of
risk reduction exceeds the improvement gained. Near to the maximum tolerable criterion, the risks are only
considered tolerable if risk reduction is impracticable or if its cost is grossly disproportionate to the improvement
gained.
Societal Risk Calculations (F-N Curve)
A determination of societal risks to the public and to employees provides important input to risk- decision
making. It provides an assessment of the magnitude of risk associated with major events, in terms of impact to
large numbers of people. Major contributors to the societal risks are also identified.
Societal risk can be represented
Quantitative Risk Assessment Report
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NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
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NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
ASSUMPTION SHEET
Project: ENGINEERING, PROCUREMENT & CONSTRUCTION OF PIPELINE INFRASTRUCTURE FOR
ESCRAVOS ENVIRONS POWER SUPPLY PROJECT (EEPSP - LOT 3)
Assumption No.: 010
Revision: 0
Date: 08/06/2023
Subject: Risk Tolerability Criteria
•
graphically, in the form of FN curves
•
numerically, in the form of a risk integral FN Curves
Societal risk can be represented by FN curves, which are plots of the cumulative frequency (F) of various
accident scenarios against the number (N) of casualties associated with the modelled incidents. The plot is
cumulative in the sense that, for each frequency, N is the number of casualties that could be equaled or
exceeded. Often ‘casualties’ are defined in a risk assessment as fatal injuries, in which case N is the number
of people that could be killed by the incidents. ‘Criterion lines’ on FN plots have been suggested as a means
to define risk zones/ categories.
Risk Integrals
The potential loss of life (PLL) is the average number of fatalities per year. HSE does not have the criteria for
PLL of onsite population. PLL will only be presented to discuss the relative ranking of hazards and the key risk
contributors. d
All the native files used for the QRA exercise will be made available to the client upon request.
Justification:
Risk acceptance criteria are used to evaluate whether the risk to people is unacceptable or within tolerable
limits.
References:
Comments:
Quantitative Risk Assessment Report
Page 58 of 99
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NGIC-EEPSP_YNL-TSF-RPT-007
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Revision No: R01
ASSUMPTION SHEET
Project: ENGINEERING, PROCUREMENT & CONSTRUCTION OF PIPELINE INFRASTRUCTURE FOR
ESCRAVOS ENVIRONS POWER SUPPLY PROJECT (EEPSP - LOT 3)
Assumption No.: 011
Revision: 0
Date: 08/06/2023
Subject: Manning Level and Distribution
Assumption:
The EEPSP facility is predominantly unmanned, hence for the IRPA calculation the Process areas of the facility, the
following onsite manning level and distribution have been considered;
Work Team / Crew
Shift Pattern
Fraction of Hours Outdoor/in
Process Area
Operation
12 hours per day / per year (365
days)
6 hours per shift (0.5)
Security
12 hours per day / per year (365
days)
(0.5)
Janitor
12 hours per day / per year (365
days)
(0.5)
Table 13: Manning Distribution for QRA
Justification:
Define manning levels and distribution for input to the QRA
References:
1) IOGP, “Process Release Frequencies,” Risk Assessment Data Directory, International Association of Oil & Gas
Producers, Report No. 434‐01, September 2019;
Comments:
Quantitative Risk Assessment Report
Page 59 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
APPENDIX B:
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
PLOT PLAN
Quantitative Risk Assessment Report
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NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
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Quantitative Risk Assessment Report
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
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APPENDIX C:
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
ISOLATABLE SECTIONS
Quantitative Risk Assessment Report
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ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Revision No: R01
ISOLATABLE SECTION BOUNDARY DESCRIPTION
Section Boundary
Isolatable
Section (IS)
IS-01
From
Colour
Code
Failure Cases
(FC) No.
To
4"-600 BA-31001
31 SDV-001A
FC-01
4” above ground line from NPSC Facility Tie in - station inlet
header
FC-02
Instrument gas from Station inlet to Instrument gas Skid.
FC-03
Inlet Filter separator package V-25001A
FC-04
IS-02
31 SDV-001A
25 PSV-001A, 25
SDV-001A, 25 PSV001B, 25 25 SDV001B, 71 SDV-001A,
71 SDV-001B
Inlet Indirect Water Bath Heater F-61001A
FC-06
Inlet Indirect Water Bath Heater F-61001B
FC-07
FC-09
IS-04
24" Pipeline
25 SDV-001A/001B
Inlet Pressure Reduction Skid – IGS/FS Skid
Inlet metering & control package 7000-PK-002
1” PRMS line – IGS /FS
FC-56
6” above ground line from CNL Facility Tie in - station inlet
header
FC-11
FC-12
Quantitative Risk Assessment Report
Inlet Pressure Reduction Skid Package
FC-10
Station Inlet
Closed drain header
Inlet Filter separator package V-25001B
FC-05
FC-08
IS-03
Section Description
1” above ground liquid outlet of the filter separators V-25001A
to closed drain V-25002
1” above ground liquid outlet of the filter separators V-25001B
to closed drain V-25002
Page 63 of 99
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EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
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Revision No: R01
FC-13
FC-14
FC-15
IS-05
31 SDV-001B/ 25
PSV-002A / 25 PSV002B/ 61-BVS-002A,
71 PSV-002A, 71
PSV-001A, 71BDV003, 31PSV-002
above ground liquid outlet of the Vent Stack 7000-FS-003
to closed drain
1” liquid outlet of Pig Receiver PR-31001 to Condensate
Accumulator V-25002
1/ ”
2
liquid outlet of the Instrument Supply Vessel to
Condensate Accumulator V-25002
FC-16
1” 7.5MMSCFD Station inlet line – 4” Inlet Isolation Vent
header.
FC-18
2” 7.5 MMSCFD Filter separator package V-25002A Pressure
Relief line to 4” Filter Separator Vent header
FC-19
2” 10 MMSCFD Filter separator package V-25002A Pressure
Relief line to 4” Filter Separator Vent header
FC-20
2”,1”, 1” 7.5 MMSCFD Filter separator package V-25002B
Pressure Relief line to 4” Filter Separator Vent header.
FC-21
2”, 1”, 1” 10 MMSCFD Filter separator package V-25002B
Pressure Relief line to 4” Filter Separator Vent header
Vent Stack
FC-22
2”, 7.5 MMSCFD Indirect Water bath heater F-61002A
Pressure Relief line to 4” WBH Vent header.
FC-23
2” 10 MMSCFD Indirect Water bath heater F-61002B
Pressure Relief line to 4” WBH Vent header.
FC-24
Quantitative Risk Assessment Report
1/ ”
2
1” 7.5 MMSCFD Indirect Water bath heater F-61002A
Pressure Relief line to 4” WBH Vent header.
Page 64 of 99
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EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
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Revision No: R01
FC-25
1” 10MMSCFD Indirect Water bath heater F-61002B Pressure
Relief line to 4” WBH Vent header header
FC-26
3” 7.5MMSCFD PRMS Relief line to 4” PRMS Vent header
FC-27
3” 10MMSCFD PRMS Relief line to 4” PRMS Vent header
FC-28
FC-29
31 SDV-001B
IS-07
25 PSV-002A , Filter
Separator V-25002A
FC-30
1”7.5MMSCFD Gas Metering System Relief line to 2” Gas
Metering Vent header.
FC-31
1”10MMSCFD Gas Metering System Relief line to 2” Gas
Metering Vent header.
FC-32
4” Pig Launcher Relief line to 4” Pig System Vent header
FC-33
4” Pig Receiver Relief line to 4” Pig System Vent header
FC-34
4” Pipeline Vent header, 4” Metring Skid 1&2 Vent header, 4”
PRMS Skid 1&2 Vent header, 4” Indirect WBH 1&2 vent
header, Inlet Isolation vent header, 4” Pigging System Vent
header to 8” Cold Vent Header
FC-35
FC-35 4” Inlet piping to Inlet Filter separator V-25002A
FC-36
FC-37
Filter Separator V25002A
Quantitative Risk Assessment Report
WBH F-61002A
2” 7.5 MMSCFD PRMS Blowdown line to 4” PRMS Vent
header.
2” 10 MMSCFD PRMS Blowdown line to 4” PRMS Vent
header.
FC-38
1” Filter separator Relief to 4” Filter separator V-25002A Vent
header
1” Filter separator Relief to 4” Filter separator V-25002A Vent
header
4” Filter separator V-25002B outlet line to inlet header WBH
F-61002B
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WBH F-61002A
31 SDV-001B
25 SDV-002A
25 PSV-002A , Filter
Separator V-25002B
Revision No: R01
FC-39
1” ” Filter separator V-25002B liquid outlet line to Condensate
accumulator
FC-40
4” Filter separator V-25002A and 4” Filter separator V-25002B
outlet to 4” WBH F-61002A inlet line.
FC-41
FC-42
Filter Separator V25002A
WBH F-61002A
25 SDV-001A
IS-08
IS-09
31 PSV-002
31 SDV-002
Quantitative Risk Assessment Report
4” WBH F-61002A outlet line to 4” WBH F-61002A Warm gas
header
1” WBH F-61002A outlet By-pass line to 4” WBH F-61002A
Cold vent header.
WBH F-61002B
FC-43
1” BDV line via 4” Filter separator V-25002A and 4” Filter
separator V-25002B outlet to 4” WBH F-61002A Cold vent
header.
25 SDV-002B
FC-44
4” WBH F-61002A outlet line via 4” WBH F-61002B cold gas
header to 4” WBH F-61002B inlet line.
FC-45
4” WBH F-61002B Outlet line via 4” WBH F-61002B Warm
gas header to PRMS.
FC-46
1” WBH F-61002B outlet By-pass line to 4” WBH F-61002B
Cold vent header.
FC-47
4” WBH F-61002B Warm gas header to 4” PRMS Header.
FC-48
4” PRMS Header via 2” line via to IGP/FS Skid
FC-49
6” Tie-in line to Pig launcher
FC-50
6” Pig Launcher line to 4” Facility Inlet line
FC - 51
1” Pig Receiver Relief line to 4” Pig Receiver Cold Vent
Header.
FC - 52
2” Pig Receiver Kicker line to 4” Facility Inlet line
61-BDV-002A, WBH
F-61002A, 71-SDV001B, 71-SDV-002B
31 SDV-002
31 PSV-003
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Revision No: R01
FC - 53
IS-10
IS-11
71 SDV-001B
28 SDV-001B
28 SDV-001B
EEPSP Power Plant
FC – 54
8” 10MMSCFD PRMS line to 8” Gas Metering System
FC - 55
8” 10MMSCFD Gas Metering System header to 8”
10MMSCFD Gas Metering System outlet line via 8” header.
FC - 56
FC- 57
IS-12
71 SDV-001A
Quantitative Risk Assessment Report
28 SDV-001A
4” 10MMSCFD PRMS line to 8” 10MMSCFD PRMS header
line
8” 10MMSCFD Gas Metering System outlet – EEPSP Power
plant
4” 7.5 MMSCFD PRMS line to 8” 10MMSCFD PRMS header
line
FC- 58
8” 7.5 MMSCFD PRMS line to 8” Gas Metering System
FC - 59
8” 7.5 MMSCFD Gas Metering System header to 8” 7.5
MMSCFD Gas Metering System outlet line via 8” header.
Page 67 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
APPENDIX D:
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
MARKED DRAWINGS OF ISOLATABLE SECTIONS
Quantitative Risk Assessment Report
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Revision No: R01
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Quantitative Risk Assessment Report
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
Page 70 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Quantitative Risk Assessment Report
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
Page 71 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Quantitative Risk Assessment Report
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
Page 72 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Quantitative Risk Assessment Report
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
Page 73 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Quantitative Risk Assessment Report
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
Page 74 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Quantitative Risk Assessment Report
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
Page 75 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Quantitative Risk Assessment Report
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
Page 76 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Quantitative Risk Assessment Report
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
Page 77 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Quantitative Risk Assessment Report
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
Page 78 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Quantitative Risk Assessment Report
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
Page 79 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Quantitative Risk Assessment Report
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
Page 80 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Quantitative Risk Assessment Report
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
Page 81 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Quantitative Risk Assessment Report
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
Page 82 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Quantitative Risk Assessment Report
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
Page 83 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Quantitative Risk Assessment Report
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
Page 84 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Quantitative Risk Assessment Report
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
Page 85 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Quantitative Risk Assessment Report
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
Page 86 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Quantitative Risk Assessment Report
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
Page 87 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
APPENDIX E:
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
EVENT TREE
Quantitative Risk Assessment Report
Page 88 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Quantitative Risk Assessment Report
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
Page 89 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Quantitative Risk Assessment Report
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
Page 90 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Quantitative Risk Assessment Report
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
Page 91 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Quantitative Risk Assessment Report
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
Page 92 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Quantitative Risk Assessment Report
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
Page 93 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Quantitative Risk Assessment Report
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
Page 94 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
APPENDIX F:
NGIC-EEPSP_YNL-TSF-RPT-007
Revision No: R01
CONSEQUENCE MODELLING RESULTS
Quantitative Risk Assessment Report
Page 95 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
NGIC-EEPSP_YNL-TSF-RPT-007
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Revision No: R01
Release Inventory Calculation
Isolatable
Section (IS)
IS-01
IS-02
IS-03
IS-04
Colour
Code
Release Hole
size
Scenario Name
Weather
Category
5D
Jet Fire Initial Release at time = 5 mins
Dispersion Initial Release after 5mins
Vapour Cloud Explosion (VCE)
Flame Length
Downwind Radiation Distances [m]
Downwind Distances [m]
Maximum Distance to Overpressures [m]
4KW/m2
12.5 KW/m2
37.5 KW/m2
UFL
LFL
50% LFL
0.02 bar
5.41
6.01
n/a
n/a
n/a
2.50
4.40
0.20 bar
n/a
0.13
bar
n/a
Small
7mm leak - Small
IS-01-S-7mm
Medium
22mm leak - Medium
IS-01-M-22mm
14.72
21.38
17.58
15.39
2.38
7.31
15.05
30.09
13.90
0.21
Large
70mm - Large
IS-01-L-70mm
35.20
61.12
46.71
39.02
6.24
24.29
63.55
119.71
71.60
68.70
Full Bore
150mm - Rupture
47.43
85.25
63.88
52.11
9.32
41.60
110.29
205.42
128.55
123.91
Small
7mm leak - Small
IS-01-FB150mm
IS-02-S-7mm
5.13
5.93
5.36
4.52
1.02
2.39
4.22
n/a
n/a
n/a
Medium
22mm leak - Medium
IS-02-M-22mm
10.02
13.34
11.30
9.96
1.65
4.96
8.52
67.20
37.23
35.42
Large
70mm - Large
IS-02-L-70mm
48.11
86.73
64.91
52.88
7.94
30.98
49.60
106.44
48.45
46.34
Full Bore
150mm - Rupture
IS-02-FB150mm
48.11
86.73
64.91
52.88
7.94
30.98
49.60
106.44
48.45
46.34
Small
7mm leak - Small
IS-03-S-7mm
Medium
22mm leak - Medium
IS-03-M-22mm
Large
70mm - Large
IS-03-L-70mm
Full Bore
150mm - Rupture
IS-03-FB150mm
Small
7mm leak - Small
IS-04-S-7mm
Medium
22mm leak - Medium
Large
Full Bore
IS-05
IS-06
Possibility
5D
5D
IS-03 to be considered as Pipeline section 2
5D
5.99
7.17
6.35
5.57
1.11
2.93
5.03
n/a
n/a
n/a
IS-04-M-22mm
9.86
18.91
14.31
12.02
2.09
6.04
10.87
26.56
13.22
12.41
70mm - Large
IS-04-L-70mm
28.90
57.38
42.43
34.76
5.21
17.69
33.43
64.65
30.26
30.19
150mm - Rupture
IS-04-FB150mm
74.15
154.43
112.46
90.49
7.40
27.27
43.95
90.12
41.68
41.17
Small
7mm leak - Small
Medium
22mm leak - Medium
Large
70mm - Large
Full Bore
150mm - Rupture
8.51
10.88
9.42
8.33
1.41
4.15
7.19
n/a
n/a
n/a
IS-04-M-22mm
21.76
34.39
27.30
23.41
3.70
11.73
29.06
51.15
26.05
24.54
IS-04-L-70mm
28.02
55.55
41.11
33.71
6.57
25.12
66.78
120.97
71.85
68.88
IS-04-FB150mm
53.83
109.78
80.49
65.17
14.75
68.64
132.05
235.80
123.39
121.73
IS-04-S-7mm
5D
Utility Line (No HC Hazard present)
Utility Line (No HC Hazard present)
IS-07
Small
7mm leak - Small
Medium
22mm leak - Medium
Large
70mm - Large
Full Bore
150mm - Rupture
Quantitative Risk Assessment Report
n/a
8.29
10.55
9.14
8.22
1.38
4.05
6.99
n/a
n/a
n/a
IS-07-M-22mm
18.09
27.36
22.06
18.95
3.09
9.26
21.43
45.22
24.90
23.68
IS-07-L-70mm
27.56
54.61
40.42
33.15
6.47
24.53
65.27
119.60
71.58
68.68
IS-07-FB150mm
54.16
110.47
81.00
65.58
14.92
58.77
88.95
185.26
90.87
88.15
IS-07-S-7mm
5D
Page 96 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
NGIC-EEPSP_YNL-TSF-RPT-007
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Revision No: R01
Release Inventory Calculation
Isolatable
Section (IS)
Colour
Code
Release Hole
size
IS-08
Possibility
Scenario Name
5D
Jet Fire Initial Release at time = 5 mins
Dispersion Initial Release after 5mins
Vapour Cloud Explosion (VCE)
Flame Length
Downwind Radiation Distances [m]
Downwind Distances [m]
Maximum Distance to Overpressures [m]
4KW/m2
12.5 KW/m2
37.5 KW/m2
UFL
6.47
7.86
6.92
6.23
1.17
LFL
50% LFL
0.02 bar
0.13
bar
0.20 bar
3.16
5.44
n/a
n/a
n/a
Small
7mm leak - Small
Medium
22mm leak - Medium
IS-08-M-22mm
9.86
18.90
14.31
12.01
2.09
6.04
10.87
26.55
13.22
12.41
Large
70mm - Large
IS-08-L-70mm
28.26
56.05
41.47
34.00
5.92
21.05
37.69
71.73
35.31
33.98
Full Bore
150mm - Rupture
IS-08-FB150mm
73.72
153.46
111.76
89.95
8.57
31.95
49.69
107.93
49.44
47.08
Small
7mm leak - Small
IS-09-S-7mm
5.75
6.85
6.07
5.09
1.08
2.81
4.84
n/a
n/a
n/a
Medium
22mm leak - Medium
IS-09-M-22mm
9.87
18.91
14.31
12.02
2.10
6.05
10.87
26.56
13.22
12.41
Large
70mm - Large
IS-09-L-70mm
29.28
58.17
43.00
35.21
4.95
16.40
31.75
61.64
28.09
26.07
Full Bore
150mm - Rupture
74.15
154.43
112.45
90.49
6.90
25.15
41.42
79.41
39.46
37.09
Small
7mm leak - Small
IS-09-FB150mm
IS-10-S-7mm
8.22
10.44
9.06
8.15
1.38
4.01
6.93
n/a
n/a
n/a
Medium
22mm leak - Medium
IS-10-M-22mm
17.20
25.71
20.81
17.85
2.94
8.73
19.67
33.87
14.64
13.48
Large
70mm - Large
IS-10-L-70mm
27.56
54.62
40.42
33.16
6.47
24.54
64.83
113.12
70.32
67.74
Full Bore
150mm - Rupture
IS-10-FB150mm
54.39
110.97
81.36
65.86
15.01
55.76
82.53
179.96
86.36
82.27
Small
7mm leak - Small
IS-11-S-7mm
1.75
1.78
0.83
n/a
0.41
0.81
1.43
n/a
n/a
n/a
Medium
22mm leak - Medium
IS-11-M-22mm
5.01
5.84
5.03
2.22
0.78
2.37
3.97
n/a
n/a
n/a
Large
70mm - Large
IS-11-L-70mm
16.58
23.57
19.34
16.58
1.11
3.13
5.10
n/a
n/a
n/a
Full Bore
150mm - Rupture
IS-11-FB150mm
31.31
51.84
40.19
33.76
1.18
3.36
5.42
n/a
n/a
n/a
Small
7mm leak - Small
IS-11-S-7mm
1.75
1.78
0.83
n/a
0.41
0.82
1.43
n/a
n/a
n/a
Medium
22mm leak - Medium
IS-11-M-22mm
5.02
5.86
5.04
2.26
0.68
2.03
3.43
n/a
n/a
n/a
Large
70mm - Large
IS-11-L-70mm
17.71
25.37
20.79
17.77
0.82
2.45
4.01
n/a
n/a
n/a
Full Bore
150mm - Rupture
IS-11-FB150mm
31.31
51.84
40.19
33.76
0.82
2.45
4.01
n/a
n/a
n/a
IS-09
IS-10
IS-11
IS-12
Quantitative Risk Assessment Report
IS-08-S-7mm
Weather
Category
5D
5D
5D
5D
Page 97 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
NGIC-EEPSP_YNL-TSF-RPT-007
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Equipment
Description
Equipment
Release size
and
Credibility
Revision No: R01
Possible outcome
Scenario Name
Weather
Category
Jet Fire Initial Release at time = 5 mins
Flame Length
Filter
Separator
V-25001A
V-25001B
Water Bath
Heater
F-61001A
F-61001B
Filter
Separator
V-25002A
V-25002B
Water Bath
Heater
F-61002A
F-61002B
Pressure
Reduction
Skid
Gas
Metering
Skid
Condensate
Accumulator
Pipeline type
V-25002
Small
7mm leak - Small
Medium
Large
22mm
leak
Medium
70mm - large
Full-bore
150mm -Rupture
V-FB-150mm
Small
7mm leak - Small
WBH-S-7mm
Medium
Large
22mm
leak
Medium
70mm - large
Full-bore
5D
V-S-7mm
-
V-M-22mm
V-L-70mm
5D
Dispersion Initial Release after 5mins
Vapour Cloud Explosion
Downwind Distance [m]
Maximum Distance to Overpressure [m]
Downwind Radiation Distance [m]
4KW/m2
12.5KW/m2
37.5W/m2
UFL
LFL
50%LFL
0.02 bar
0.13 bar
0.20 bar
5.18
5.99
5.41
4.62
0.95
2.41
4.25
n/a
n/a
n/a
10.52
14.16
11.95
10.49
1.73
5.21
9.07
n/a
n/a
n/a
24.69
39.39
30.96
26.03
4.38
14.30
37.46
n/a
n/a
n/a
47.93
86.34
64.64
52.67
8.65
33.83
53.10
n/a
n/a
n/a
4.84
5.54
5.02
3.90
0.91
2.25
3.97
n/a
n/a
n/a
WBH-M-22mm
9.74
12.89
10.94
9.66
1.61
4.82
8.24
n/a
n/a
n/a
WBH-L-70mm
23.67
37.37
29.48
24.80
4.20
13.39
34.95
65.21
36.84
35.13
150mm -Rupture
WBH-FB-150mm
45.94
82.08
61.62
50.29
7.86
30.50
48.86
104.68
47.46
45.59
Small
7mm leak - Small
V-S-7mm
8.12
10.29
8.93
8.04
1.36
3.96
6.84
n/a
n/a
n/a
Medium
V-M-22mm
16.09
23.68
19.27
16.37
2.75
8.11
17.54
32.25
14.32
13.24
Large
22mm
leak
Medium
70mm - large
V-L-70mm
27.57
54.64
40.44
33.17
6.47
24.55
63.30
109.67
61.60
58.69
Full-bore
150mm -Rupture
V-FB-150mm
54.72
111.67
81.86
66.27
14.94
51.98
75.55
166.46
83.61
80.20
Small
7mm leak - Small
WBH-S-7mm
7.79
9.73
8.52
5.04
1.32
3.73
6.51
n/a
n/a
n/a
Medium
WBH-M-22mm
14.79
21.42
17.57
13.98
2.49
7.39
15.17
30.30
13.94
12.96
Large
22mm
leak
Medium
70mm - large
WBH-L-70mm
33.28
56.37
43.32
36.09
6.14
23.06
58.85
106.53
60.99
58.24
Full-bore
150mm -Rupture
WBH-FB-150mm
63.55
121.56
88.90
71.05
12.83
47.34
70.10
156.15
73.85
70.38
Small
7mm leak - Small
PRS-S-7mm
Medium
22mm
leak
Medium
Large
70mm - large
PRS-L-70mm
Full-bore
150mm -Rupture
PRS-FB-150mm
Small
7mm leak - Small
GM-S-7mm
Medium
22mm
leak
Medium
Large
70mm - large
GM-L-70mm
Full-bore
150mm -Rupture
GM-FB-150mm
Small
7mm leak - Small
CA-S-7mm
Medium
Large
22mm
leak
Medium
70mm - large
Full-bore
150mm -Rupture
Release size
and
Credibility
Possible outcome
Quantitative Risk Assessment Report
-
-
-
-
-
-
5D
5D
5D
PRS-M-22mm
On Hold pending availability of Vendor Information
5D
GM-M-22mm
On Hold pending availability of Vendor Information
5D
1.10
1.77
1.08
0.81
n/a
n/a
n/a
n/a
n/a
n/a
CA-M-22mm
2.97
4.99
2.83
1.46
n/a
0.19
0.29
n/a
n/a
n/a
CA-M-70mm
12.04
15.70
13.78
12.99
n/a
n/a
27.56
63.85
36.58
34.93
CA-FB-150mm
21.12
30.64
25.54
22.99
n/a
26.38
39.72
80.47
45.87
44.40
Page 98 of 99
NNPC GAS INFRASTRUCTURE COMPANY LIMITED
NGIC-EEPSP_YNL-TSF-RPT-007
EPC OF PIPELINE INFRASTRUCTURE FOR ESCRAVOS
ENVIRONS POWER SUPPLY PROJECT (EEPSP–LOT 3)
Equipment
Description
Equipment
Release size
and
Credibility
Revision No: R01
Possible outcome
Scenario Name
Weather
Category
Jet Fire Initial Release at time = 5 mins
Flame Length
2Km Pipeline
8 Km Pipeline
Dispersion Initial Release after 5mins
Vapour Cloud Explosion
Downwind Distance [m]
Maximum Distance to Overpressure [m]
Downwind Radiation Distance [m]
4KW/m2
12.5KW/m2
37.5W/m2
UFL
LFL
50%LFL
0.02 bar
0.13 bar
0.20 bar
5.41
6.30
5.68
3.65
1.54
7.47
21.36
32.77
22.48
21.86
14.93
21.77
17.88
15.65
4.80
23.34
65.24
99.87
67.75
65.81
Small
7mm leak - Small
Medium
22mm
leak
Medium
Large
70mm - large
29.74
50.98
39.13
32.40
7.00
18.00
42.78
86.21
48.98
46.73
Full-bore
100mm -Rupture
30.41
51.69
39.93
33.70
10.21
50.59
119.94
196.43
126.80
122.60
Small
7mm leak - Small
5.42
6.31
5.69
5.05
1.05
2.52
4.45
n/a
n/a
n/a
Medium
22mm
leak
Medium
14.97
21.84
17.93
15.70
2.42
7.44
15.47
30.44
13.97
12.98
Large
70mm - large
45.37
83.68
62.75
51.94
7.95
34.34
88.55
162.47
96.03
92.02
Full-bore
150mm -Rupture
57.79
110.31
81.47
66.51
10.65
49.23
123.85
233.84
142.13
136.59
Quantitative Risk Assessment Report
5D
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5D
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