Influence of Fabric Overlap on the Ultimate Capacity of Pipes Rehabilitated with Fiber-Reinforced Composite

Steel pipelines must endure various of stresses during their service life, as they are subject to harsh elements, such as salt water, or corrosive chemicals that may cause external or internal defects in pipe wall. These defects, could in turn affect the pipes performance, in which case, the pipe must be either strengthened or repaired. A relatively new method of pipeline repair in use today is the application of fiber-reinforcement plastic composites (FRP) as external reinforcement. Typically, this includes the use of a unidirectional, continuous strand glass fiber fabric in a resin, wrapped around the region of the defect, in order to improve the local strength properties of pipe. As the region of defect becomes large or continues over a long length of pipe, multiple stripes of fabric must be used to cover the area. Due to the limitations of the practical dimensions of these fabrics, the ultimate capacity of the repaired system is affected by the resulting fabric overlap configuration. This study was done as a preliminary examination of the effects of the overlap configuration resulting from wrapping of such composite around steel pipes on the pipe’s ultimate capacity. Several wrapping configuration were investigated in this phase of our study. Reinforced (wrapped) pipe specimens were fabricated and tested to attain the ultimate capacity of the repairs under quasi-stasis internal pressure. The experimental results showed that from a comparative viewpoint, most of the configurations investigated did not significantly affect the capacity of the pipe when FRP was wrapped circumferentially. However, the biased wrap configuration proved to be the most efficient wrapping configuration.

Keywords:

composites , FRP , pipe , rehabilitation , repair