Repair of Through-Wall Piping Defects Using Carbon Fiber Composite Repair System

Uninhibited internal corrosion can create several different types of through-wall defects in pipelines. Circular holes, axial slots, and circumferential slots are three potential leaking situations that can develop as corrosion occurs internally on different piping systems. Theoretically, each defect can be repaired by a composite repair system in accordance with design equations given in the ASME PCC-2 Article 4.1 and ISO 24817 nonmetallic repair standards, however, empirical analyses for these types of through-wall defects do not always hold true in test environments. In this work, design equations were analyzed according to ASME PCC-2 Article 4.1 and ISO 24817 for a specific carbon fiber composite repair system on specific defect sizes and configurations. Test spools of different geometries were fabricated with circular holes, axial slots, and circumferential slots of pre-determined dimensions. A carbon fiber reinforced epoxy composite system was installed and hydro-tested over the three different defect types and the results are compared to the standard design equations. It was determined that although the ASME and ISO equations were conservative enough to predict significantly lower failure pressures for these repairs, the current models can almost be considered overly conservative and not accurately modeling the actual failure mechanism occurring in these types defects repaired with composite repairs.