Buried pipelines are the prime mode used by the energy industries in North America for transporting petrochemical gases and liquids and these pipelines are often subjected to large deformations due to various effects. These may result in the formation of wrinkles in the pipe wall. No information is available to assess the safety and integrity of such a wrinkled pipeline. As a result, to avoid any probable catastrophe, the pipeline industry usually replaces the wrinkled portion even though such remedial action, which can cost millions of dollars, may not always be necessary.

This research program was designed to evaluate the structural integrity and assess the remaining life of wrinkled energy pipelines. To achieve the objectives, the research program was divided into three components:​ (i) full-scale laboratory tests on pipeline, (ii) development of finite element (numerical) models, and (iii) development of a fracture life assessment model using material tests. Results from full-scale pipe tests and numerical analyses show that a pipe does not fail in fracture if the pipe is subjected to an axisymmetric axial monotonic deformation. However, a fracture is developed in the wrinkle region if the wrinkled pipe is subjected to strain reversals due to a cyclic load history. The strain values at the wrinkle region reach a very high value before a fracture is obtained.

A series of a special kind of material test (strip test), developed at University of Alberta, was conducted in the last part of the research program, to understand the local behavior of a pipe wrinkle subjected to strain reversals. The data of strip tests was then used to develop a fracture life assessment model. The fracture model was calibrated to the cyclic full-scale pipe tests and it was found that the model works well and usually predicts a conservative value.