Performance of a carbon-fiber/epoxy composite for the underwater repair of pressure equipment

The use of composite materials to rehabilitate damaged piping and pressure vessels has been growing in recent years. Most of these repairs occur onshore to either aboveground or buried pressure equipment. Recently, there has been increasing demand for these systems to repair damaged systems offshore or in submerged environments. This paper details the test and performance of a composite repair system that has been installed and cured while submerged. Testing was performed on a coupon-level to investigate the impact of an aqueous submersion on materials properties. Additionally, full scale testing on three pipe geometries, straight, elbow, and tee, with through-wall defects were also performed to determine the influence of water contact on repair efficacy. Results indicated that the short-duration water exposure for the coupons has little statistically significant effect when compared to samples cured under ambient conditions. Failure pressures of the pipe specimens repaired underwater were lower than specimens that had been repaired dry.