Structural Integrity of Energy Pipelines: Assessment, Reliability and Optimization

加压钢质管道被广泛认为是运输大量碳氢化合物产品的最经济的方式。加拿大能源管道行业运营着约11.5万公里的石油和天然气输送管道。维护这一庞大管道网络的完整性和安全运行具有重大的社会和经济意义。有助于管道运营商实现这一目标的新知识、新模式和新方法具有重要的实用价值。该研究计划旨在维护钢质管道在各种威胁下的结构完整性，包括以下项目：1)开发基于可靠性的管道腐蚀管理方法；2)开发多目标优化维护策略；3)研究用于确定断裂韧性的单边拉伸试件。在过去的十年中，基于可靠性的管道腐蚀管理计划越来越受到管道运营商的关注，因为这样的计划提供了一个适当的框架来考虑腐蚀检测和评估中涉及的各种不确定性。项目1)的成果将填补关于腐蚀缺陷空间相关性的知识空白，并提供一个概率框架，以基于检测数据同时推断管道上腐蚀缺陷的数量和增长。这些方法将导致与腐蚀管道相关的退化过程的真实建模，这对于确定复查间隔、准确评估管道的随时间变化的可靠性以及制定同时满足资源和可靠性约束的阶段性缺陷缓解计划至关重要。优化的管道维修决策具有显著的社会经济效益和社会效益。项目2)的成果将为管道工程师选择维护计划提供指导，以最大限度地提高可靠性/安全性，同时将成本降至最低。这不仅从管道运营商的角度，而且从位于管道附近的普通公众的角度来看，都是有价值的。基于应变的评估越来越多地被用于处理由于例如斜坡移动和地面下沉而施加在管道上的大塑性变形。在基于应变的含平面缺陷(即裂纹)管道的评定中，断裂韧性阻力曲线是一个重要的输入参数。近十年来，利用单边拉伸试件进行断裂韧性的实验测定在管道行业引起了极大的关注，因为由单边拉伸试件测得的断裂韧度与足尺管的断裂韧度更相关。项目3)的成果将促进基于单边拉伸试件的断裂韧性测试程序的开发和标准化，这将导致更准确地评估断裂韧性，从而更准确地对含裂纹管道进行基于应变的评估。

Pressurized steel pipelines are widely recognized as the most economical means to transport large quantities of hydrocarbon products The Canadian energy pipeline industry operates approximately 115,000 km of oil and gas transmission pipelines. Maintaining the integrity and safe operation of this vast pipeline network has significant social and economic implications. New knowledge, models and methodologies that will assist the pipeline operators in achieving this goal are of significant practical value. The proposed research program is aimed at maintaining the structural integrity of steel pipelines under various threats, and consists of the following projects, namely 1) developing reliability-based pipeline corrosion management methodologies, 2) developing multi-objective optimal maintenance strategies, and 3) investigating the single-edge tension specimen for determining the fracture toughness. Over the last decade, the reliability-based pipeline corrosion management program has received growing attentions from pipeline operators because such a program provides an appropriate framework to account for various uncertainties involved in the corrosion inspection and assessment. The outcome of project 1) will fill the knowledge gap with respect to the spatial correlation of corrosion defects and provide a probabilistic framework to simultaneously make inference of the number and growth of corrosion defects on pipelines based on the inspection data. These methodologies will lead to realistic modeling of the degradation process associated with a corroding pipelines, which is critical to the determination of re-inspection interval, accurate evaluation of the time-dependent reliability of the pipeline and development of a phased defect mitigation plan that satisfies both the resource and reliability constraints. Optimal maintenance decisions for pipelines have significant safety and economic benefit to the society and the. The outcome of project 2) will provide guidance to pipeline engineers on the selection of maintenance plans to maximize reliability/safety and minimize cost at the same time. This is valuable not only from the perspective of the pipeline operators but also from the perspective of general public located in the vicinity of the pipelines. The strain-based assessment is being increasingly used to address large plastic deformation imposed on pipelines due to, for example, slope movement and ground subsidence. The fracture toughness resistance curve is a key input in the strain-based assessment of pipelines containing planar defects (i.e. cracks). The use of the single-edge tension specimen to experimentally determine the fracture toughness has gained much attention in the pipeline industry over the last decade, because the fracture toughness determined from such type of the specimen is more relevant to that of the full-scale pipe. The outcome of project 3) will facilitate the development and standardization of the single-edge tension specimen-based fracture toughness testing procedure, which can lead to more accurate evaluation of the fracture toughness and consequently more accurate strain-based assessment of pipelines containing cracks.