Composite Repair of Pipelines with Axial Flaws

摘要

Fiber-reinforced composites have been used to repair a wide variety of structural defects in pipelines and pressure equipment with good success. Repaired defects range from non-leaking to through-wall damage generated by corrosion or other mechanisms. Primary design guidance for these repairs is given in ASME PCC2 Article 4.1, where Section 3.4.6 addresses the repair design of a leaking substrate. The design equations in this section are derived from thin film bulge testing which determines the load that initiates interfacial fracture between the repair and substrate. These equations typically assume a rigid substrate, which is appropriate when testing thin films, but fails to adequately describe repairs on pipes and pipeline components. As such, predicted failure pressures for repairs on long axial flaws have been found to typically be much higher than observed during testing. This paper will describe testing of composite repaired pipes with long axial flaws of various lengths. Variables, including repair thickness, width, and geometry, were also investigated. Two pipe diameters have also been tested to investigate the effects of substrate stress on the repair performance.