The Design, Development and Validation of an Innovative High Strength, Self Monitoring, Composite Pipe Liner for the Restoration of Energy Transmission Pipelines

The research described in this paper centers on a composite of thermoplastic materials that can be inserted in a degraded steel pipe to completely restore its strength. Through the use of fabrics consisting of ultra high strength fibers that are co-helically wrapped over a thin walled thermoplastic cylindrical tube that serves as a core, arbitrarily high pressures can be achieved. This paper first outlines the design, manufacturing and installation procedures developed for this unique material to provide a context for the engineering research. Based on this outline, the technological basis that has been developed for assuring the strength and long term durability of this concept during its insertion, and in its very long term service as a liner in energy transmission pipelines, is presented in detail. The research that is described includes burst testing of the material in stand alone pipe form, load/elongation testing of ultra high strength fabrics, and linear and nonlinear elastic and viscoelastic analysis models. This body of work indicates that the concept is fundamentally feasible for restoring a wide range of large diameter natural gas and liquid transmission pipelines to be able to carry arbitrarily high pressures over very long lifetimes. It also indicates that liners can be safely installed in long lengths even in lines with severe bends in a continuous manner. With further research the concept has the potential for eliminating hydro testing and smart pigging during service, and could possibly be installed in some lines that are currently unpiggable.