Concurrent Technologies Corporation

9 http://ammtiac.alionscience.com http://wstiac.alionscience.com BACKGROUND Modern US Navy ships use considerable quantities of piping to carry fresh water, ballast water, chilled water, wastewater and fuels throughout the ship. Traditionally, copper-nickel (90Cu-10Ni) alloy pipes have been used, but they are heavy, subject to both corrosion and moderate bio-fouling, and are expensive to procure, install, and maintain. As each new generation of warships is designed to provide greater capabilities and typically require longer mission time, weight savings and reduced maintenance costs are continually sought. On the other hand, decades of experience has proven the suitability of copper nickel piping. Potential replacement materials must meet high performance requirements and demonstrate adaptability to shipbuilding requirements. The incumbent material is familiar to constructors, who have developed techniques to position and join sections of Cu-Ni piping (e.g., welding and brazing) that are flexible and allow in-situ adjustments as construction proceeds. One particular aspect of performance that is of critical interest to the US Navy, the ability to withstand substantial shock events encountered during warfare, is so well validated by real world experience that there is no formal shock testing requirement for copper-nickel piping per se. One candidate piping replacement material system is glassreinforced plastic (GRP) composite piping. The Navy has conducted numerous evaluations of GRP piping materials over the past 30+ years with very little transition to application. One study1 in particular, conducted by Conroy, et al., of the David W. Taylor Naval Research and Development Center, has served as a cornerstone for the design guidelines and specification requirements currently in place for GRP piping. This study, as well as several others since that time, was conducted on epoxy-resin GRP piping systems. However, as with most technologies, the materials and manufacturing technologies related to GRP piping have continued to evolve such that the GRP piping materials available today are much different than those available 10 or 20 years ago. One available family of GRP piping materials is FIBERBOND®* composite piping, a vinyl ester resin material reinforced with glass fiber. This piping system has been certified by the American Bureau of Shipping (ABS), Lloyd’s of London, and the US Coast Guard for use on commercial vessels and in various offshore and other special applications. FIBERBOND® piping is also used by the Royal Navy in the ballast area of the HMS Bulwark assault ship. In that application 1600 feet of 10-inch diameter pipe reduced the ship’s weight by 75 tons and saved $600,000 in acquisition and installation costs. One area that has seen considerable development in this GRP piping system is the joining technique. The TigerwrapTM joining technique, developed by ITT has proven to be durable and can be readily applied in the field to adaptable piping systems. Concurrent Technologies Corporation (CTC), in collaboration with the Naval Sea Systems Command (NAVSEA), ITT Specialty Products, Gibbs and Cox, and others, developed a multi-year project to determine the capability of current GRP piping material to meet the defined needs of the naval shipbuilding community. The ultimate goal of the project was to test and qualify GRP piping for use in US Navy shipboard piping applications. Nevertheless there are many questions that must be addressed before any new system can be accepted to replace a successful material system. GRP piping is inherently resistant to corrosion and offers significant weight saving potential, but its response to shock events was not well known; and its ability to meet stringent fire performance requirements was also uncertain. Finally, achieving acceptance by the Navy requires meeting a relatively new set of requirements, the Naval Vessel Rules (NVR), which had not previously been used to approve piping systems.