Why is Australia different from the rest?
To start with, let us make clear that the above headline refers to the rate of pipeline failure in Australia vs that in the rest of the world. The Journal certainly would not dream of making comparisons with any other aspect of life or engineering between that stimulating country (where it is headquartered) and any other community anywhere else!
But in terms of their failure rates, pipelines in Australia are happily different from other pipelines around the world, and the reasons for this are by no means clear. The rates of pipeline failure in Australia are substantially lower than in the Americas and Europe, at only 10-20% of the international mean for failures in onshore transmission pipelines.
At the recent Joint Technical Meeting held in Sydney between the Australian Pipeline Industry Association (APIA), the European Pipeline Research Group (EPRG), and Pipeline Research Council International (PRCI), this issue was examined in depth in a paper from Peter Tuft and Sergio Cunha which is published in this issue of the Journal (on pages 277-300). The authors looked at the validity of the Australian data and then explored reasons for the difference. Some reasons are obvious, such as the relative youth of Australian pipelines which results in a negligible rate of corrosion failure. However, there is no obvious explanation for the markedly lower rate of failure due to third-party damage. It is hypothesized that Australian practices for managing third-party damage may differ in some way and the authors suggest that, given the high social and economic cost of pipeline failures, there should be a comparative study to identify any beneficial differences between the third-party damage protection practices in Australia and those elsewhere.
The background to this paper is the significant fact that that the Australian pipeline industry has been collecting incident data since about 1965. The lines for which data are collected are gas and liquid transmission pipelines that comply with the over-arching Australian pipeline industry standard AS 2885, and with a maximum allowable operating pressure above 1050 kPa. The resulting database contains about 100 fields to record data about the pipe itself, the events causing the incident, details of any damage and repairs, and operating practices (particularly relating to external interference protection). Reporting is voluntary, and data are collected by the APIA from members of its Pipeline Operators Group (POG). Messrs Tuft and Cunha point out that POG members represent 94% of the total transmission pipeline length in Australia; each year POG member companies submit a signed declaration that they have either reported all incidents or have had none.
In their paper, the authors point out that the mostly likely explanation for the low rate of third-party damage failures in Australia is a potentially different approach to managing such interference. Exactly what that difference might be is not clear and there has been no study that casts light on this area. They go on to speculate on the Australian practices which might contribute to low third-party failure rates, although they are only very tentative in their explanations for the different failure rates pending a time when there is better information on whether practices elsewhere do in fact differ significantly. Despite these reservations, the authors suggest several factors that may be of relevance:
- Australian pipelines in populated areas tend to be patrolled frequently, usually on the ground but sometimes by air. In and around at least two major cities the transmission pipelines are patrolled every day – or every weekday – and in other cities they are patrolled weekly. The incident database contains about 20 near-miss events where patrollers have caught third parties in the act of digging or preparing to dig on the right-of-way (RoW), and there are many more instances where work near the pipeline was forestalled by patrollers before encroaching on the RoW (such off-RoW activity is not reportable, but there is ample anecdotal evidence).
- The ‘One-Call’ or ‘Dial-Before-You-Dig’ system is well used in Australia by third parties with only rare lapses.
- Pipeline marker signs tends to be frequent, conspicuous, and explicit in their warning message.
- Since 1997, AS 2885 has required a safety-management study to be undertaken during design and then reviewed every five years or whenever the environment around the pipeline changes (such as for new urban development). This study is a fine-grained analysis, often on a metre-by-metre basis, of all possible causes of pipeline failure. Threats to pipeline integrity are explicitly identified and mitigated, with great emphasis on protection against third-party damage.
- While the safety-management study is an engineering process, it may have a cultural side effect: because it is integral to Australian pipeline design and operation it may help keep safety matters – and particularly the consequences of pipeline failure – in the forefront of pipeline engineers’ thinking at all times.
Messrs Tuft and Cunha reiterate that all or none of these factors may be responsible for the low rates of Australian failures due to third-party damage, although they at least suggest possible initial directions for investigation. As they go on to conclude, the absence of a simple explanation for the low Australian failure rate is not a clear-cut and satisfying conclusion. However the objective of their paper is to initiate discussion of whether others might benefit from research into the differences between Australian and international failure rates. The authors believe it provides a convincing case that Australian pipeline failure rates are indeed substantially lower than elsewhere, and hence that investigation of that difference has potential to provide benefits in reducing failure rates in other parts of the world.
How do earthquakes affect pipelines?
Seismic design and engineering of pipelines has advanced significantly in recent decades, although little has been accomplished to address the vulnerability of buried pipelines to seismic hazards. In their paper on pages 335-344, Indranil Guha and his co-authors examine this proposition from the viewpoint of the Indian sub-continent which has a record of earthquakes of varying magnitude and devastation. Since 2003, for example, there have been 18 major earthquakes in the country, averaging around 5 on the Richter Scale, but peaking at over 9. As this paper explains, with new and proposed cross-country pipelines in India, it is becoming more important to understand the effects on buried pipelines of seismic hazards (such as shaking, liquefaction, and fault surface rupture).
India, of course, is not alone in suffering from such tectonic issues. In 1974 the first seismic design code Technical standard for oil pipelines was developed by the Japan Roads Association, and in 1984 the American Society of Civil Engineers (ASCE) first published formal guidelines for seismic design of pipeline systems; however, until 2007, there was no specific standard for seismic design of pipeline systems. In that year the Gujarat State Disaster Management Authority (GSDMA) published a standard for Indian application, as the State was the worst one affected during the 2001 Bhuj Earthquake, in which over 20,000 people died; numerous public- and privately-owned oil and gas companies have pipeline networks within the State. The first draft of the standard resulted from a project at the Indian Institute of Technology in Kanpur, sponsored by GSDMA. An analysis of the effect of earthquakes on a continuous pipeline in the state of Gujarat in India was subsequently presented based on the GSDMA report, in which the authors also discuss the design and construction methodology to minimize the effect of loading on the pipeline during ground movement.
In summary, the paper by Guha et al. provides an overview of past performance of buried pipelines during earthquake events, including fault rupture, liquefaction, and seismic shaking, and goes on to illustrate the nascent understanding of earthquake hazards both around the world and in India. Identification of seismic sources and geohazard-prone areas during the early phases of a project allows these data to be incorporated during the design phase. Appropriate site-specific seismic design during the engineering stage can then reduce the risks posed by earthquake hazards on buried pipeline structures.
The September, 2014, issue of the Journal will explore these issues at greater depth: under the guest editorship of Prof. Shawn Kenny – the Wood Group Chair in Arctic and Harsh Environments Engineering in the Faculty of Engineering and Applied Science at the Memorial University of Newfoundland, and a member of the Journal’s Editorial Board – a special issue is being planned around the topic of engineering analysis and design for seismic ground movement. Prof. Kenny is soliciting contributions for this issue, and further details can be obtained from him (firstname.lastname@example.org) or the Journal’s editor (see page 274).