The damage consisted of CUI on a 2-inch (50.8-mm) carbon steel line at a double elbow with a tee in the center. Because of the odd geometry – with elbows on both sides of a tee joint – and the proximity of the carbon steel line to other pipes and equipment, there was relatively limited access to damaged areas. A successful composite repair would not only have to be installed in tight conditions, it would also have to meet a design temperature of 100˚F (38˚C) and a design pressure of 285 psi (2 MPa) while operating at 100 psi (0.7 MPa).
Based on engineering and qualification testing, CSNRI determined that the Thermo-Wrap system was the most appropriate solution. Thermo-Wrap™ is a factory-saturated, custom engineered composite repair system compatible with temperatures up to 330°F (165°C).
CSNRI trained and qualified installers from a local contractor began preparing the pipe surface for the composite system installation. Unfortunately, during the preparation process, a through wall hole was accidentally opened. Modifications needed to be made to the repair design so the final repair would be able to address a through wall defect. The design for the Thermo-Wrap system used for the repair was amended to withstand a through wall defect, and repair work proceeded, with the line shut down for safety.
Two technicians applied Thermo-Wrap to the full length of both elbow joints, completing the repair in a matter of hours with no special equipment or hot work required.
CSNRI delivered a fast, reliable and extremely cost-effective solution to a potentially costly and unsafe issue for the chemical plant. The Thermo-Wrap composite system enabled safe, uninterrupted service for 5 years and was deemed serviceable by the plant owner for another 2 years. If the next turnaround has not been scheduled at that time, the integrity of the repair will be reassessed to determine if it is suitable for continued safe service.
Having the CSNRI composite repair perform so successfully allowed the plant to continue safe and effective operations without worrying about the status of the line. Based on the exceptional performance of the Thermo-Wrap repair, the plant owner could safely plan to leave the repaired piping in service at least another 2 years, when the next scheduled turnaround would be scheduled.