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

钢质管道输送石油、天然气和石油产品。加拿大拥有世界第二大管道网络，管道传输业为加拿大国内生产总值(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，它们被称为地下管道。埋地管道在各种外力的作用下会产生许多缺陷，如凹痕。凹痕缺陷可能会导致管道失效；例如，凹痕可能会导致破裂或泄漏，造成深远的后果。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，已经完成了确定埋地能源管道中这些凹陷缺陷是如何形成的，以及这些凹陷缺陷可能导致的故障。大多数埋在地下的管道都受到周围土壤的约束；它们形成了受约束的凹陷。然而，研究仅在具有无约束凹陷的管道样本上完成。因此，这些以前的研究没有提供关于约束凹陷的油气管道的结构行为的知识。此外，目前的凹陷评估标准使用管道凹陷的深度(管壁向内凹陷的数量)作为确定管道因凹陷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，它受到了许多研究人员的批评。管道失效的评估应该基于凹陷应变(管壁中的拉伸量)，因为它更准确地反映了实际情况。因此，NSERC的这项研究计划是以制定基于应变的牙齿评估标准为目标设计的。这一标准将是可靠的，能够准确地评估埋地石油和天然气管道在承受石油和天然气压力时因约束凹陷而造成的故障。因此，本研究的预期意义在于建立基于应变的含凹坑油气管道缺陷评定标准。这一标准目前还不存在，但有很大的必要性。随着它的发展，管道行业、工程师和监管政府机构将能够正确评估埋地管道中各种凹陷缺陷导致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造成的后果，如向环境中释放石油和天然气。这项计划亦可为管道营办商节省收入，并尽量减少供应给社会和各行各业的石油和天然气供应中断。**

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. **