Rehabilitation of Submerged Pipes with FRP Technology

Carbon and glass fiber reinforced polymers (CFRP/GFRP) have been used for rehabilitation of pipelines since late 1990s, and the technology has been gaining more acceptance in the pipeline industry due to the advantages it provides such as ultra-high strength, corrosion resistance, ability to install on any shape and material of pipe, and long service life with minimal or no maintenance. The majority of pipeline rehabilitation projects with the fiber reinforced polymer (FRP) technology are comprised of internal or external repair of pressure pipes in dry or low-moisture condition. Recent advances in formulating hydrophobic (and occasionally hydrophilic) adhesives, as well as under-water cure saturants, have provided the opportunity to repair piping systems that are underwater (mostly oil and gas pipes) or large diameter pipes without the need for bypassing the flow (mostly in wastewater conveyance). Nevertheless, repairing a pipeline that is submerged or in live flow imposes certain challenges with respect to design, materials, and installation, which may require divers that are trained to install the product with special equipment. QuakeWrap has been developing FRP systems that are suitable to install in submerged and live flow conditions for the past eight years after receiving a request from the Indonesian oil conglomerate Pertamina Oil, which tested this CFRP system installed underwater, and the results were encouraging. These efforts have continued to improve its external FRP wrapping system (SuperLaminate-X) over the years to achieve stronger adhesion and performance with improved resins, fabrics, and installation practices. Recently, a specialty installation contractor, Bulldog Diving, has performed mock installations of this CFRP system to repair a defective pipe in their training tank (approximately 10 ft. deep). The defective pipe sample (with a 1-in. hole) wrapped with this FRP system underwater, and then was sent to manufacturer’s R&D lab for pressure testing, which yielded failure at 600 psi by means of a leak through the edges in compliance with the failure mode set forth by ASME PCC-2 Part 4. The next step in wet applications of this FRP repair system is installing precured patches along a 48-in. sewer pipe in the Washington, DC, sewer system. The manufacturer and Bulldog Diving have successfully tested this repair system and are currently preparing for the actual pilot installation. Attendees of this presentation will learn about the development of submerged and underwater pipe repairs with a highly engineered FRP system installed with a unique procedure by divers.