Pattern Studies of the Strain Distributions for Detecting Pipe Wrinkling

As both the onshore and offshore pipeline constructions push further into higher risk terrains, such as geologically unstable terrain and Arctic region, the risk of local buckling failure (wrinkling) for these buried pipelines has been increasing gradually. However, previous methods used to prevent the buried pipelines from buckling failure are expansive, time consuming, and unreliable. Therefore, to overcome these problems, a reliable method to predict pipeline wrinkling has been proposed. The method can provide active warning for pipeline wrinkling through a decision-making system (DMS). The DMS was designed to identify the strain distribution patterns and their development on the critical pipe segments for early detecting the onset of pipe wrinkling. To conduct the reliable DMS, studies of the strain distribution patterns on the line-pipes during pipe buckling are very important. In this paper, the strain distribution patterns of various line-pipes were presented. These line-pipes have different material and geometric properties, loading conditions, and manufacturing conditions. A total of 32 sets of experimental results and 72 sets of finite element analysis (FEA) along with parametric studies were included in the study. The study concluded significant behavioural characteristics revealed on the strain distribution patterns during pipe buckling and important parameters affecting these strain patterns. For practical application, three thresholds of the strain distribution patterns were proposed. Furthermore, the optimal positions and spacing of the strain measurements for early detecting pipelines wrinkling were discussed as well.