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A QRA approach to pipeline failure

29 January 2014

The next generation of oil and gas pipelines must be robust, cost effective and fit for purpose. Failure is not an option.

Given the challenge facing a number of ERM clients in this area, there was considerable interest in a paper presented by Glenn Pettitt, ERM’s Technical Director at the Rio Pipeline Conference and Exposition 2013. Glenn outlined the use of Quantitative Risk Assessment (QRA) in pipeline development, the aim being to strike the right balance between risk reduction and cost.

Targetted risk assessment
QRA in this context is conducted by quantifying the extent to which the risk of pipeline failure can be reduced by applying a number of standalone risk reduction measures. The diameter of the pipe, the support structures used and  route taken by the pipeline may all have an impact on operational safety, suggested Glenn, a pipeline specialist. But the key factor in this type of QRA, he told an audience of industry professionals, is the cumulative effect on reducing and tailoring the risk of failure when several mechanisms are applied simultaneously. Once the measures have been applied, a follow-up QRA can be carried out to determine the extent to which risks have been reduced.

As part of his presentation, Glenn examined different failure scenarios in order to determine how various risk reduction mechanisms can reduce their frequency and how this can be applied to a QRA of pipeline systems. This approach, for example, could help to determine whether the  wall of pipe needs to be thicker and more robust for certain loads and sensitive environments. It can show the pipeline’s vulnerability in different regions and can demonstrate the effects of various measures. A pipeline deemed vulnerable to vandalism or theft could, for example, be buried at a greater depth and be fitted with a vibration detector to alert support teams in the event of any interference.,.   

Avoiding the unnecessary
A key theme of the paper included quantifying just how much risk reduction can be achieved by applying a combination of the various mechanisms that are designed into a pipeline system to reduce the risk of failure. 

Glenn made the point that while there may be a quantitative benefit in applying different risk reduction mechanisms, there may also be a quantifiable case for demonstrating that additional mechanisms may not be required, depending upon the location and other individual circumstances (e.g. mountainous terrain or high instances of oil theft and sabotage). It is an approach already attracting the attention of cost conscious pipeline project managers.

In the case of pipeline development, Glenn’s paper reminded his audience that the well- established concept of ALARP, reducing the risk to a level that would be considered “as low as reasonably practicable” was relevant. A QRA for pipeline development is all about focusing on the individual circumstances of a particular project.

Ageing pipelines
The main objective of the conference was to share technological advances and operational experiences from major existing pipeline projects.  It also aimed to encourage more collaboration between companies which operate in different segments of the pipeline industry: operation, construction, engineering, research and development, training and equipment suppliers.  The conference raised a number of important issues currently facing pipeline operators, among them the age of installations and how best to maintain and, where appropriate, upgrade them. The frequency of inspection regimes to determine issues such as corrosion and stress was a particularly relevant topic in the context of ageing pipelines.

For further information and a copy of Glenn Pettitt’s presentation email glenn.pettitt@erm.com

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