STAGE 1 FINAL HAZARD ANALYSIS FOR BETHUNGRA LINE VALVE TO BOMEN

Transcription

1 STAGE 1 FINAL HAZARD ANALYSIS FOR THE YOUNG TO BOMEN PIPELINE - FROM 8 KILOMETRES NORTH OF BETHUNGRA LINE VALVE TO BOMEN Prepared for: APA Group Document Number: APAGRO\ Revision B Prepared by: Karin Nilsson 22 June 2010 PO Box 248 Berowra Heights NSW 2082 Telephone: [02] Facsimile: [02] Planager@bigpond.net.au

2 Stage 1 Final Hazard Analysis for the Young to Bomen Pipeline - From 8 kilometres north of Bethungra Line valve to Bomen Acknowledgment The author would like to thank Rehan Bukhari for his assistance in preparing this report. Disclaimer This report was prepared by Planager Pty Ltd (Planager) as an account of work for the APA Group. The material in it reflects Planager's best judgement in the light of the information available to it at the time of preparation. However, as Planager cannot control the conditions under which this report may be used, Planager and its related corporations will not be responsible for damages of any nature resulting from use of or reliance upon this report. Planager's responsibility for advice given is subject to the terms of engagement with APA Group. Rev Date Description Prepared By Reviewed By Authorised By A 21/06/2010 Draft for Comment Karin Nilsson Maarten Tentij Rehan Bukhari B 22/06/2010 Final Report Karin Nilsson Maarten Tentij Rehan Bukhari Stage 1 Final Hazard Analysis For The Young To Bomen Pipeline - From 8 Kilometres North Of Bethungra Line Valve To Bomen

3 CONTENTS EXECUTIVE SUMMARY... I GLOSSARY... III 1 INTRODUCTION Background Scope and Aim of Study Input into the FHA The Project DESIGN AND OPERATION Main Changes Made to the Pipeline Since the Preliminary Hazard Analysis Evaluation Against PHA Assumptions MAIN SAFETY RISKS IDENTIFIED Safety Related Hazards and Risks Identified Comparison with Issues Raised in the Preliminary QRA REVIEW OF THE MAIN PREVENTATIVE AND PROTECTIVE SAFEGUARDS PROPOSED FOR THE PIPELINE IMPLICATIONS OF THE RESULTS OF THE HAZOP STUDY Results IMPLICATIONS OF THE RESULTS FROM THE SAFETY MANAGEMENT STUDY CONCLUSIONS AND DISCUSSIONS REFERENCES Stage 1 Final Hazard Analysis For The Young To Bomen Pipeline - From 8 Kilometres North Of Bethungra Line Valve To Bomen

4 EXECUTIVE SUMMARY To meet the rising demand for natural gas to the towns in the central south of NSW and to a new power station at Uranquinty, the East Australian Pipeline Pty Ltd (EAPL), a wholly owned subsidiary of APA Group, is proposing to loop the existing 12 Young to Bomen pipeline with an 18 pipeline which would run parallel to the existing pipeline. Due to the potentially hazardous nature of natural gas, the pipeline is classified as potentially hazardous as per the definition by the NSW Department of Planning. As one element of the planning approval process, a Preliminary Hazard Analysis (PHA) was prepared in October 2009 in accordance with the requirements of the NSW Department of Planning as stated in their Hazardous Industry Planning Advisory Paper (HIPAP) No. 6: Guidelines for Hazard Analysis (Reference 1) and for the risk to be evaluated and compared with their risk criteria, as specified in their HIPAP No. 4: Risk Criteria for Landuse Planning (Reference 2). The Department of Planning requires the risk to be re-evaluated at the final design stage and for a Final Hazard Analysis (FHA) to be prepared for the project. The aim of the FHA is to analyse and assess the hazards and resultant residual risk associated with the pipeline at the final design stage. As such, the FHA complements the PHA which was conducted at the early design stage. This FHA has been prepared as a Supplement to the PHA, and as such focuses on the differences that have evolved during the development of the project through its design phases. The scope of the PHA was to assess the risk associated with the natural gas pipeline from the point where the pipeline leaves the compressor station at Young up to the point where the pipeline enters the metering station at Bowmen amounting to a 131 km long pipeline. The pipeline from Young to Bomen will be constructed in two stages. Stage 1 is currently being undertaken, in which the pipeline is being constructed from Bomen metre station to 8 kilometres north of Bethungra Line valve, a total length of 61 kilometres. The present report summarises the results of the FHA for the Stage 1 pipeline from Bomen metre station to 8 kilometres north of Bethungra Line valve. Stage 1 Final Hazard Analysis For The Young To Bomen Pipeline - From 8 Kilometres North Of Bethungra Line Valve To Bomen i

5 If and when Stage 2 is constructed, the FHA will need to be re-validated based on the detailed design risk review for the pipeline from the tie-in point 8km north of the Bethungra Line valve up to the compressor station at Young. By conducting a thorough review of all studies subsequent to the PHA it is possible to determine whether the design has altered sufficiently to warrant a comprehensive re-evaluation of the risk assessed, or whether the design basis has remained basically intact. Three studies were reviewed in detail: The PHA (completed in October 2009), The Hazard and Operability (HAZOP) Study (completed in December 2009) for Stage 1 only and The Pipeline Safety Management Study (completed in November 2009) for Stage 1 only. The HAZOP and SMS have been undertaken for Stage 1 looping only. In the future, as and when Stage 2 looping is undertaken, a separate HAZOP and SMS for Stage 2 will be conducted. The FHA will need to be re-validated once the Stage 2 HAZOP and SMS have been conducted During the PHA process, a number of potential hazards were identified with possible major consequences. The subsequent studies (above) did not uncover any further hazards or risks associated with this pipeline. The safety management study further concluded that the risk of a rupture for the pipeline in this location is virtually negligible through design and layout. The result of these hazard and risk assessment studies conducted subsequent to the PHA have had the effect of further reducing the likelihood of events with potentially major consequences compared with what was assumed in the PHA. Hence, the result of these subsequent studies is to somewhat reduce the risk associated with the pipeline. As the quantitative risk calculations in the PHA are based on historic incident data, such reduction in risk can only be expressed on a qualitative basis and the quantitative risk assessment in the PHA remains valid though slightly conservative. Based on the hazard and risk reviews carried out as part of the Young to Bomen pipeline project it can be concluded that, at the final design stage, the fire and explosions risks associated with the proposed Stage 1 pipeline remain acceptable with regards to all current definitions of the tolerability of risk. Specifically, the pipeline within it s easement is well within the criteria for risk of fatality for both residential and industrial areas. Stage 1 Final Hazard Analysis For The Young To Bomen Pipeline - From 8 Kilometres North Of Bethungra Line Valve To Bomen ii

6 GLOSSARY APT HAZID HAZOP HIPAP LFL MAOP MPa MSDS MW NG OH&S PHA QRA Australian Pipelines Trust Hazard Identification Hazard and Operability Study Hazardous Industry Planning Advisory Paper Lower Flammable Limit Maximum Allowable Operating Pressure Mega Pascal (unit for pressure) Material Safety Data Sheet Mega Watt (unit for energy output) Natural gas Occupational Health and Safety Preliminary Hazard Analysis Quantitative Risk Analysis Stage 1 Final Hazard Analysis For The Young To Bomen Pipeline - From 8 Kilometres North Of Bethungra Line Valve To Bomen iii

7 d REPORT 1 INTRODUCTION 1.1 BACKGROUND To meet the rising demand for natural gas the towns in the central south of NSW and to a new power station at Uranquinty, the East Australian Pipeline Pty Ltd (EAPL), a wholly owned subsidiary of APA Group, is proposing to loop the existing 12 Young to Bomen Pipeline with an 18 Pipeline which would run parallel to the existing pipeline. Due to the potentially hazardous nature of natural gas, the pipeline is classified as potentially hazardous as per the definition by the NSW Department of Planning. One of these Conditions relate to the need to undertake a Final Hazard Analysis (FHA) at the conclusion of the design phase for the project but before construction: Prior to the commencement of commissioning of the project upgrade, the Proponent shall prepare and submit for the approval of the Director-General, a Final Hazard Analysis prepared in accordance with the Department s Hazardous Industry Advisory Paper No. 6 Guidelines for Hazard Analysis The pipeline from Young to Bomen will be constructed in two stages. Stage 1 is currently being undertaken, in which the pipeline is being constructed from Bomen metre station to 8 kilometres north of Bethungra Line valve, a total length of 61 kilometres. The present report summarises the results of the FHA for the Stage 1 pipeline from Bomen metre station to 8 kilometres north of Bethungra Line valve. If and when Stage 2 is constructed, the FHA will need to be re-validated based on the detailed design risk review for the pipeline from the tie-in point 8km north of the Bethungra Line valve up to the compressor station at Young. 1.2 SCOPE AND AIM OF STUDY The scope of this FHA (as for the PHA) is to assess the risk associated with the natural gas pipeline from Bomen metre station to 8 kilometres north of Bethungra Line valve, a total length of 61 kilometres. Stage 1 Final Hazard Analysis For The Young To Bomen Pipeline - From 8 Kilometres North Of Bethungra Line Valve To Bomen 1

8 d This document was prepared in accordance with the Department of Planning s Hazardous Industry Planning Advisory Paper (HIPAP) number 6 Guidelines Hazard Analysis (Ref 3) and the risks were compared with the criteria in use by the Department for land use planning as per HIPAP number 4 (Ref 4). The aim of a FHA is to analyse and assess the hazards and resultant residual risk associated with the plant and processes at the final design stage. The types of risks considered in this FHA are: Risk of acute human injury or fatality; Risk of acute damage to the natural environment. By agreement with the NSW Department of Planning, and in line with the guidelines on Hazard Analysis, this FHA has been prepared as a Supplement to the PHA, and as such focuses on the differences that have evolved during the development of the project through its design phase and its review and amendment by the process hazard and risk reviews subsequent to the PHA process. 1.3 INPUT INTO THE FHA The following hazard and risk reviews are used as inputs to the FHA: Preliminary Hazard Analysis (Ref 5) Young to Bomen (131 km); Young - Wagga Looping HAZOP Study (Ref 6) Stage 1: 8 kilometres north of Bethungra Line valve to Bomen (61 kilometres); Pipeline Safety Management Study Young - Wagga Loop Stage 1 (Ref 7) Stage 1: 8 kilometres north of Bethungra Line valve to Bomen (61 kilometres);. 1.4 THE PROJECT The pipeline will run south west from the Young Compressor Station towards the Bowmen Meter Station. The pipeline will be constructed in two Stages with the present FHA covering Stage 1 only. The existing pipeline is bi-directional also enabling Moomba gas from South Australia to flow to Victoria and Bass Strait gas from Longford to flow to Sydney. The new (parallel) pipeline will also be bi-directional. The pipeline route traverses the Young, Cootamundra, Harden and Junee Shire Council areas in NSW. The area is predominantly used for grazing and cropping. An aerial photograph is presented below. The pipeline will be entirely located inside the existing easement. The pipeline construction will require a working width slightly wider than the easement. Stage 1 Final Hazard Analysis For The Young To Bomen Pipeline - From 8 Kilometres North Of Bethungra Line Valve To Bomen 2

9 Figure 1 Corridor for Pipeline Route Stage 1 Final Hazard Analysis For The Young To Bomen Pipeline - From 8 Kilometres North Of Bethungra Line Valve To Bomen 3

10 2 DESIGN AND OPERATION 2.1 MAIN CHANGES MADE TO THE PIPELINE SINCE THE PRELIMINARY HAZARD ANALYSIS There have been no substantial changes in the proposed design and operation of the Stage 1 pipeline since the early design stage and as assumed in the PHA. Compared with the design of the proposed development which was known (and assumed) at the time of the PHA (Ref 5), the only differences are: The design of pipeline and equipment is now finalised. The control and protective systems have been determined for the pipeline. Note that since the new pipeline will run within an existing easement, the pipeline layout was determined also at the PHA stage. 2.2 EVALUATION AGAINST PHA ASSUMPTIONS There have been no changes to the main assumptions with regards to the Stage 1 pipeline design and operation made in the PHA. Table 1 Summary of Preliminary Assumptions Made in the PHA for the Pipeline Design Item Percent operational Pipe Diameter Pipe Length Maximum Allowable Operating Pressure (MAOP) Actual operating pressure Temperature Class Location to AS2885 Pipe Thickness Pipeline Design All data used in the present risk assessment are for a pipeline pressurised 100% of the time. 450 mm NB (nominal bore) 130 kilometre 10.2 MPa, ANSI Class MPa 25 o C R1 (broadly rural) with 40 hectare blocks with some R2 (rural residential) as per AS2885 definitions. 6.8 mm to 9.7mm Stage 1 Final Hazard Analysis For The Young To Bomen Pipeline - From 8 Kilometres North Of Bethungra Line Valve To Bomen 4

11 Table 1 Summary of Preliminary Assumptions Made in the PHA for the Pipeline Design Item Depth of Cover Number of flanges Features Design Standard Pipeline Design At least 900mm (or 450mm in rock if encountered) 5 flange joints per mainline valve (MLV) with four MLVs along the pipeline. Pressure indication and Actuator Line Break (ALB) on each MLV. As per AS2885 requirements The assumptions in the PHA remain valid with regards to design assumptions for the Stage 1 pipeline. Stage 1 Final Hazard Analysis For The Young To Bomen Pipeline - From 8 Kilometres North Of Bethungra Line Valve To Bomen 5

12 3 MAIN SAFETY RISKS IDENTIFIED 3.1 SAFETY RELATED HAZARDS AND RISKS IDENTIFIED The main risk associated with the pipeline relates to the transport of natural gas which is flammable when released into the atmosphere. The PHA concluded that a leak of flammable natural gas would generally only have the potential to cause injury or damage if there was ignition, which resulted in a fire or (in case of confinement) an explosion incident. The factors involved are: - The pipeline must fail in a particular mode causing a release. There are several possible causes of failure, with the main ones being corrosion and damage by external agencies. - The released material must come into contact with a source of ignition. In some cases this may be heat or sparks generated by mechanical damage while in others, the possible ignition source could include non-flame proof equipment, vehicles, or flames some distance from the release. - Depending on the release conditions, including the mass of flammable material involved and how rapidly it ignited, the results may be a localised fire (for example a jet fire), a flash fire or an explosion of the vapour cloud formed through the release. - Finally, for there to be a risk, people must be present within the harmful range (consequence distance) of the fire or explosion. How close the people are will determine whether any injuries or fatalities result. Environmental damage from gas fire incidents are generally associated with a failure to control fire water used. Natural gas is a buoyant, flammable gas which is lighter than air (relative density of 0.6). On release into the open the non-ignited gas tends to disperse rapidly at altitude. Ignition at the point of release is possible, in which case the gas would burn as a jet (or torch) flame. On release in an enclosed area an explosion or a flash fire is possible. The gas is non-toxic, posing only an asphyxiation hazard. Due to its buoyancy, any release of credible proportions from operations of this scale, in the open, would not present an asphyxiation hazard. With standard confined space entry procedures and appropriate security arrangements to prevent unauthorised access to any of the facilities the risk associated with asphyxiation from natural gas is be minimal. Locally, the pressure of the compressed gas may be hazardous in case of an uncontrolled release. These hazards, while of importance for people working with the gas pipeline, do not have implications beyond the immediate location of Stage 1 Final Hazard Analysis For The Young To Bomen Pipeline - From 8 Kilometres North Of Bethungra Line Valve To Bomen 6

13 the release unless the released gas is ignited. Therefore, the risk associated with of non-ignited compressed gas does not form part of the scope of the present risk assessment. This potential risk would, however, need to be closely managed through job safety analysis (JSA) and/or other risk assessment practices used by management and maintenance workers (in accordance with NSW Occupational Health and Safety Act and its associated legislation (Reference 8)). A total of 10 potentially hazardous scenarios were identified in the PHA for the gas pipeline, as listed in Table 2 below. These remain valid also at this final design of Stage 1 pipeline. Table 2 - Summary of Identified Hazards Number Hazardous Event Potential 1 Mechanical damage to the pipeline 2 Corrosion 3 Nearby explosion at neighbouring natural gas pipeline 4 Pressure excursion 5 Spontaneous loss of integrity of pipe (rupture) 6 Erosion 7 Land subsidence 8 Aircraft, train or heavy vehicle crash 9 Damage to pipeline through terrorism / vandalism 10 Neighbouring bush fire 3.2 COMPARISON WITH ISSUES RAISED IN THE PRELIMINARY QRA Comparing the issues and concerns listed above with those raised in subsequent studies (HAZOP and SMS) show that while the HAZOP (Ref 6) and the SMS (Ref 7) detail the threats which could potentially lead to the above hazards, the studies did not identify any further hazardous incident scenarios requiring analysis. The studies undertaken at the more detailed stage of the design of the pipeline have not revealed any major changes (to the installations, material, or systems) that could seriously increase or change the risk associated with the pipeline in Stage 1 compared with that assessed in the PHA. Stage 1 Final Hazard Analysis For The Young To Bomen Pipeline - From 8 Kilometres North Of Bethungra Line Valve To Bomen 7

14 4 REVIEW OF THE MAIN PREVENTATIVE AND PROTECTIVE SAFEGUARDS PROPOSED FOR THE PIPELINE The Hazard Identification Word Diagram in Table 8 in the PHA summarises the potential hazards identified for the pipeline, their initiating causes, consequences, together the manner in which they are prevented and/or their impact is mitigated. When comparing the hazards and control mechanisms reported in the PHA (Ref 5) with what has been described in the HAZOP (Ref 6) and the SMS (Ref 7), for Stage 1 pipeline, the main control systems remain valid though the SMS and the HAZOP have identifies some further control mechanisms in place. The table from the PHA can be used to describe the situation at the Stage 1 pipeline in it s final design. The quality and effectiveness of the safeguards listed in the PHA are periodically reviewed and checked by internal and external auditors using the APA Group and the Department of Industry & Investment audit procedures. These audits include engineering, safety, process and quality audits. Stage 1 Final Hazard Analysis For The Young To Bomen Pipeline - From 8 Kilometres North Of Bethungra Line Valve To Bomen 8

15 5 IMPLICATIONS OF THE RESULTS OF THE HAZOP STUDY 5.1 RESULTS The HAZOP Study for the Stage 1 pipeline assessed the hazard and operability of the pipeline from the point near Bethungra up to the point where it comes into Bomen (total of 61km). It also assessed the hazard and operability of a typical line valve bypass which is used to allow flow either to blowdown vent for depressurisation or around closed Main Line Valve for repressurisation. The recommendations for further improvements of the pipeline design and operation coming out of the HAZOP were very minor in nature and included some small design changes and some changes to the Piping and Instrument Diagrams. Stage 1 Final Hazard Analysis For The Young To Bomen Pipeline - From 8 Kilometres North Of Bethungra Line Valve To Bomen 9

16 6 IMPLICATIONS OF THE RESULTS FROM THE SAFETY MANAGEMENT STUDY The Safety Management Study (SMS) (Ref 7) was carried out in accordance with the requirements in AS and as required by the Conditions of Consent for the Stage 1 pipeline. The SMS is, in it s nature, highly detailed and assesses the threats and hazards to the pipeline at each location along it s full length. A total of 234 threats were identified, many of which were repeated for several locations along the pipeline. Particular attention was given to external interference threats as these are seen as by far dominating the causes of incidents relating to pipelines. The most serious threat which could be anticipated for a pipeline in this location, as identified in the SMS, includes excavators, rippers, and post hole augers. However, the SMS determined that it would be rare for anything other than light machinery (backhoes, graders) to be used near the pipeline, particularly at short notice. The SMS calculated the resistance of then pipeline to penetration from external interference. The SMS concluded that no pipe can be punctuated by an excavator fitted with general purpose teeth. Further, is concluded that penetration by drill bit is possible but will not result in rupture. The SMS also concluded that while penetration of the thinner (standard) 6.8mm thick pipe by both points of a tiger tooth on a 32 tonnes excavator may create a hole larger than the critical defect length, this is a limiting case and as such is barely credible. The SMS determined that the only possible threat to the pipeline which may result in rupture is a large ripper. However, the study concluded that provided that the thicker walled pipeline (9.7 mm wall thickness) is used in the industrial area near Bomen and provided that the pipeline is buried at 1200mm depth at this point, the rupture scenario is not credible. The PHA assumed that, while highly unlikely, the rupture scenario is still possible and the quantitative risk calculations included the rupture scenario. The risk calculations in the PHA remain valid though somewhat conservative. The FHA will need to be re-validated for the Stage 2 pipeline after conducting the SMS for this portion of the pipeline. Stage 1 Final Hazard Analysis For The Young To Bomen Pipeline - From 8 Kilometres North Of Bethungra Line Valve To Bomen 10

17 7 CONCLUSIONS AND DISCUSSIONS The findings in the Stage 1 FHA confirmed the conclusions in the PHA (Ref 5), that the proposed Young to Bomen pipeline does will not introduce undue risk, and that there is no reason, on land use safety planning grounds, why the proposed development should not be approved. From a land use safety point of view, only minor changes have been made to the pipeline since the stage of the PHA. These changes are related to improvements of the operation and the safety of the proposed pipeline. They result in a somewhat reduced risk from the pipeline compared with the risk assumed at the stage of the PHA. In conclusion, the risk calculations made in the PHA remain valid and the risk contours and risk profiles determined in PHA are still applicable for the Young to Bomen pipeline. The FHA will need to be re-validated for the Stage 2 pipeline if and when it is constructed. The assessments made in the various safety related studies (HAZOP, Safety Management Study) have demonstrated the importance of ensuring continued good practice for operating and maintenance standards, ensuring that the procedures and systems are kept up to date and that training and drills in emergency response are undertaken regularly. Stage 1 Final Hazard Analysis For The Young To Bomen Pipeline - From 8 Kilometres North Of Bethungra Line Valve To Bomen 11

18 8 REFERENCES 1 Hazardous Industry Planning Advisory Paper No. 6 (HIPAP No. 6): Guidelines for Hazard Analysis, NSW Department of Planning 2 Hazardous Industry Planning Advisory Paper No. 4 (HIPAP No. 4): Risk Criteria for Landuse Planning, NSW Department of Planning 3 Department of Planning, Hazardous Industry Planning Advisory Paper Nº 6: Guidelines for Hazard Analysis; NSW Government, Sydney, Hazardous Industry Planning Advisory Paper No. 4 (HIPAP No. 4): Risk Criteria for Landuse Planning, NSW Department of Planning 5 Nilsson K, Preliminary Hazard Analysis of the Natural Gas Delivery Pipeline between Young and Bomen in NSW, Planager Pty Ltd, 13 October Tuft P, Young - Wagga Looping HAZOP Study, Peter Tuft & Associates, 2 December Tuft P, Pipeline Safety Management Study Young - Wagga Loop Stage 1, Peter Tuft & Associates, 30 November NSW Occupational Health and Safety Act and its associated legislation, including but not limited to the Dangerous Goods Regulations, Construction Safety Regulations, and the Factories Shops and Industries Regulations Stage 1 Final Hazard Analysis For The Young To Bomen Pipeline - From 8 Kilometres North Of Bethungra Line Valve To Bomen 12