APPLICATION OF TITANIUM IN SHIPBOARD SEAWATER COOLING SYSTEMS

Abstract

ABSTRACTTitanium alloys are evaluated as an alternative to the current copper‐nickel components now employee in U.S. Navy surface ship seawater cooling systems. Titanium offers a solution to the accelerated seawater corrosion and erosion related attack being experienced in seawater systems aboard CG‐47 class cruisers as well as other ship classes and can provide a means for extending service life and substantially improving reliability. Both the positive and potentially negative aspects of utilizing titanium in piping and heat exchangers are reviewed. Titanium's excellent resistance to corrosion and erosion attack, good yield strength and relatively low density permit use of thinner‐walled, reduced diameter piping and heat exchanger tubing (relative to copper‐nickel) and thus offer reduced system weight and volume. System design strategies are discussed for eliminating or greatly mitigating the adverse effects of galvanic corrosion and marine biofouling, the two major concerns when applying titanium in seawater piping and heat exchanger systems.An overall assessment of titanium versus copper‐nickel alloys is provided with regard to piping and heat exchanger fabrication, cost, performance, design criteria, piping component (valves, pumps, etc.) selection criteria, and operational limitations. Specific topics addressed as part of that assessment include: (1) shipyard fabricability of titanium piping systems and onboard repair; (2) biofouling experience and biofouling control techniques with titanium in seawater; (3) galvanic corrosion effects when titanium is coupled to active (less noble) metals and the strategies for eliminating the risk of galvanic attack. The viability of titanium for surface ship seawater systems is summarized, and areas of future work are discussed with the intent of providing guidance for successful application of titanium in shipboard seawater systems.