Pattern Studies of Strain Distributions for Detecting Pipe Wrinkling

As both onshore and offshore pipeline constructions push further into higher risk terrains, such as geologically unstable terrain and the Arctic region, the risk of local buckling failure (wrinkling) for these buried pipelines has been increasing gradually. However, current methods used to prevent buried pipelines from buckling failure are expensive, time consuming, and unreliable. Therefore, to overcome these problems, a reliable method of predicting pipeline wrinkling is proposed. The method can provide active warning for pipeline wrinkling through a decision-making system (DMS). The DMS has been designed to identify strain distribution patterns and their development on critical pipe segments and detect the onset of pipe wrinkling. To create a reliable DMS, studies of the strain distribution patterns of line-pipes during pipe buckling are very important. In this paper, the strain distribution patterns of various line-pipes are 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 analyses (FEA) along with parametric studies were included in the study. The study revealed significant behavioral characteristics of the strain distribution patterns during pipe buckling and important parameters affecting these strain patterns. For practical application, three thresholds of the strain distribution patterns are proposed. Furthermore, the optimal positions and spacing of the strain measurements for early detecting pipelines wrinkling are discussed as well.