Retrofitting of pipelines

The use of CTech-LLC composite systems to strengthen and/or rehabilitate existing pipelines is increasingly gaining widespread acceptance among power plant and utility facility managers.

The versatility of the linings to conform to a wide range of diameters and lengths, their high strength properties, light weight, impermeability, thinness and fast rate of application/installation are some of the reasons why many managers prefer FRP linings to other retrofit alternatives.

However, some managers may still have the misconception that FRP lining installation requires significant operational downtime.

Recent advances in FRP technology, as well as improved installation methodologies have significant decreased the installation time. FRP linings typically consist of fabrics made with high strength fibers that are soaked in an adhesive resin, and are applied like wall paper to the interior or exterior of the pipe surface.

The high strength fibers are typically composed of bundles of very thin strands of glass, carbon, aramid or Kevlar. Once the resin cures, the fabric turns into a very thin (typically about 0.05 inch thick) composite laminate.

The density and orientation of the high-strength fibers, as well as the fiber type are parameters that the engineer can vary in order to create customized FRP linings that meet specific project criteria.

When applied to the inner surface of a pipeline, the FRP composite CTech-LLC^® systems becomes a trenchless structural rehabilitation alternative, where all labor, equipment and materials are introduced into the pipeline through service access points, thus avoiding the need for excavation.

Since many major pipelines lie under freeways and urban or industrial developments, excavation is not possible without major disruptions to traffic, production, or other normal operations. The economic impact of the disruptions, coupled with the significant investment required to replace deteriorated pipelines, increase the appeal of this trenchless retrofit option.

Although the use of FRP composite CTech-LLC^® systems has focused on the rehabilitation of deteriorated pipelines that have been in service for decades, they can also be used to correct design and/or construction errors of new pipelines.

Such was the case of the low-pressure pipeline at the “El Encanto” Hydroelectric Power Plant located 75 miles northwest of San José, Costa Rica. This project included the installation of about 150,000 ft2 of FRP lining, and is the largest reported FRP pipeline retrofit project completed to date in a single phase.

CTech-LLC^® systems are used to perform:

• Increase bending strength
• Leak remediation and prevention
• Protection from corrosion and replacing strength lost due to corrosion
• Emergency repairs
• Seismic upgrades
• Increase available hoop stress (increase internal pressure capacity)
• Strengthening Water transmission lines or large-diameter pressure pipes, either internally or externally.