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Composite repair systems are a proven solution for offshore applications because they are quick to install, reduce or completely avoid service downtime, provide structural reinforcement and corrosion prevention, and can be installed on challenging pipelines experiencing internal and external corrosion, dents, erosion, and other defects without downtime or costly replacement.
This solution is lighter and safer than conventional repair methods (e.g. steel sleeves plus hot work like welding), making it ideal for challenging offshore structures and environment. Offshore environments also expedite corrosion and pipelines often develop pits which, in addition to weakening the metal structure, can have an equally negative effect on joints and welds. Over time, stress caused by pits lead to structural weaknesses and, if left unaddressed, eventually cause fractures.
In a recent in-line inspection (ILI), an offshore pipeline operator in Hong Kong identified extensive pitting in a 508mm (20 inches) OD fuel pipeline which is operating at design pressure of 50bar (725psi) and design temperature of 45oC(113oF). In some portions of the pipe pitting had resulted in 50% wall loss.
The company addressed this problem with a carbon fiber composite repair and engaged the local contractors and HJ3 to expedite the entire repair work.
A team of specially trained local experts cleaned the riser, grit-blasting it with an SSPC SP10 surface preparation removing rust, coating, and mill scale to produce a near-white surface prior to the application of the HJ3’s CarbonSeal™ HT1 system.
The defects were identified and marked so they could be appropriately treated with HJ3’s CarbonSeal™ Filler. The defects, which were concentrated near the weld, were repaired with 2 layers of CarbonSeal™ HT1. Additionally, the carbon fiber high temperature composite repair system was installed over the entire 14 inches and 22 inches length of the repair respective for each pipeline. The repair is designed for a20 year design life.
The HJ3 CarbonSeal™ HT1 repair system installation was performed in 3 days of on-site work (including the final inspection) without taking the pipeline out of service.
