Wrinkles on a pipeline, whether produced intentionally by construction methods of vintage pipelines or unintentionally by bending loads from subsurface geotechnical movements, introduce significant stress concentration factors. However, common options for pipeline repair usually cannot be used given the protruding wrinkle geometry (e.g. steel sleeves), or are costly and can introduce additional safety concerns (e.g. pipe replacement). Numerous composite repair technologies have been developed that take the form of the underlying structure and, thus, may provide an alternative for this application. However, composite repairs have focused on restoring axial defects in pipelines (i.e. hoop reinforcement), while restoring the bending capacity of wrinkled pipe is less common. Therefore, this literature review consolidates the current state of knowledge regarding the effects of composite repairs on the bending load capacity of pipes.
The reviewed literature identified 14 studies (using finite element analysis, full-scale testing, or a combination of both) that investigated composite repairs on wrinkled pipe or under bending loads. Typically, for pipe with non-sharp flaws (e.g. corrosion or wrinkles), the bending capacity of the pipe with a sufficient repair is increased near or beyond that of pristine pipe. The latter case usually results in a new wrinkle forming outside of the repaired pipe section. Most repairs have also been shown to prevent significant plastic deformation of the base pipe beneath the repair. However, knowledge gaps are also identified by this review and present opportunities for future studies to further improve the performance of composite repairs for this application.