Development of Strain-Based Defect Assessment Criteria for Oil and Gas Pipelines

钢铁管道运输石油、天然气和石油产品。加拿大拥有世界上第二大的管道网络，管道输送行业为加拿大的国内生产总值（GDP）增加了约88亿美元。因此，油气管道的安全和不间断运行至关重要。这些管道大多在地下运行；因此，它们被称为埋地管道。埋地管道在各种外力作用下产生许多缺陷，如凹痕。凹痕缺陷可能导致管道失效；例如，凹痕可能导致破裂或泄漏，产生深远的影响。石油或天然气可能被释放，造成环境破坏、健康危害和石油和天然气供应中断。因此，研究已经完成，以确定这些凹痕缺陷是如何在埋地能源管道中形成的，以及这些凹痕缺陷可能导致的故障。大多数地下管道受到周围土壤的限制；它们形成受约束的凹痕。然而，研究只完成了无约束凹痕的管道样本。因此，这些先前的研究并不能提供有约束凹痕的油气管道结构行为的知识。此外，目前的凹痕评估标准使用管道凹痕的深度（管壁向内凹痕的数量）作为确定管道因凹痕缺陷而失效的可能性的主要因素。这种基于凹痕深度的标准是不现实的，受到了许多研究者的批评。对管道失效的评估应该基于凹痕应变（管壁的拉伸量），因为它更准确地反映了现实情况。因此，NSERC的研究项目旨在制定基于应变的凹痕评估标准。该标准将是稳健的，能够准确评估埋地油气管道在油气压力作用下的约束凹痕所导致的失效。因此，本研究计划的预期意义在于开发具有约束凹痕的油气管道的基于应变的缺陷评估标准。这个标准目前还不存在，但它是非常必要的。随着它的发展，管道行业、工程师和政府监管机构将能够正确评估埋地管道中各种凹痕缺陷引起的破裂或泄漏的可能性。因此，这项研究的好处是，它将有助于减少管道故障及其后果，如石油和天然气释放到环境中。它还将为管道运营商节省收入，并最大限度地减少对我们社区和各个行业供应的石油和天然气的中断。**

Steel pipelines transport oil, gas, and petroleum products. Canada has the second-largest pipeline network in the world, and the pipeline transmission industry adds about $8.8 billion to Canada's gross domestic product (GDP). Hence, the safety and the uninterrupted operation of oil and gas pipelines are paramount. The majority of these pipelines run underground; thus, they are called buried pipelines. Buried pipelines develop many defects, such as dents, from a variety of external forces. Dent defects may cause the pipes to fail; for example, dents may cause ruptures or leaks that have far-reaching consequences. Oil or gas may be released, causing environmental damages, health hazards, and oil and gas supply interruption. Thus, research has been completed to determine how these dent defects form in buried energy pipelines, and the possible failures that can result from these dent defects. Most buried pipelines are constrained by soil around them; they form constrained dents. However, studies were only completed on pipe specimens with unconstrained dents. As a result, these previous studies do not provide knowledge of the structural behavior of oil and gas pipelines with constrained dents. Furthermore, the current dent assessment criteria uses the depth of a pipe's dent (the amount that the pipe wall has been dented inwards) as is the primary factor to determine the chance that a pipe will fail because of its dent defect. This criteria based on dent depth is unrealistic, and it has been criticised by many researchers. The assessment of a pipe's failure should be based on dent strain (the amount of stretching in the pipe wall) instead, as it more accurately reflects real-life situations. This NSERC research program has therefore been designed with the objective of developing strain-based dent assessment criteria. This criteria will be robust, able to accurately assess failures caused by constrained dents in buried oil and gas pipelines when the pipes are subjected to oil and gas pressures. Hence, the anticipated significance of this research program is the development of strain-based defect assessment criteria for oil and gas pipelines with constrained dents. This criteria does not currently exist, but there is a great necessity for it. With its development, the pipeline industry, engineers, and regulatory governmental bodies will be able to correctly assess the possibility of ruptures or leaks caused by a variety of dent defects in buried pipelines. Thus, the benefit of this research is that it will assist in reducing pipeline failures and their resulting consequences, such as the release of oil and gas into the environment. It will also save revenue for pipeline operators and minimize the interruption of oil and gas that is supplied to our community and to various industries. **