Initial imperfections and pipeline buckling

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The high demand of energy requires the safe transport of gaseous and liquid energy resources from northern regions to areas of demand. Recently, the advance in metallurgy has allowed the manufacturing of high strength steel pipelines for the containment and transport of such material. While these high strength pipelines allow for the reduction of the initial cost by reducing the wall thickness required, they are also susceptible to ground movements that can cause large deformations. Such ground movements are primarily due to movement of ground slopes and relative settlement of areas of freezing and thawing. In severe ground movement cases, these large deformations can lead to loss of containment with very high impact on the industry and the environment. The University of Alberta in collaboration with the pipeline industry has been extensively studying the large deformations of pipelines in the forms of wrinkles and buckles and has identified that a major factor for the initiation of buckles in a pipeline is the amount and distribution of the initial imperfections in the pipeline profile (e.g. out or roundness, out of straightness, ripples). While numerical models are able to predict the behaviour of the pipeline based on a certain distribution of initial imperfections, no data is available on the pipeline profile and the associated initial imperfections. The current project proposes measuring the amount of initial imperfections within manufactured pipelines and comparing the different pipeline manufacturers that are frequently employed in the industry. The proposed project relies on manufacturing special devices and the purchase of high resolution camera systems that are able to quickly profile the pipeline with very high accuracy. The results will help categorize the type, extent and distribution of the initial imperfections and will allow for accurate modelling of energy pipelines subjected to large deformations.