Additive isolation covering (as shown on a commercial-grade bolt and stud) can reduce costs and improve schedule over the current isolation method used on Navy ships for fasteners on dissimilar metals. Kestrel Partners, Inc., photo
This project will investigate a more durable isolation material added directly to the fasteners during manufacture and will leverage commercially available materials to validate use for Navy-defined requirements. The expected results will address galvanic corrosion issues in flange assemblies on six ships in the LPD 17 Class that are outfitted with titanium seawater piping system and potentially benefit other similar applications to address life-cycle and repair costs.
The current isolation sleeves used on fasteners to prohibit electrical connectivity of dissimilar metals are prone to damage due to general assembly and misalignment issues.
The project team, consisting of NAVSEA 05P2; Naval Surface Warfare Center, Carderock Division; PMS 470 and NMC, will validate the use of the additive isolation coated fasteners through both mechanical performance testing of the coated fastener and localized testing of the isolation material. A mock-up assembly will be tested to validate proper isolation protection between the dissimilar metals. These results will be compiled and provided to NAVSEA 05P2 to develop the Materials Selection Information documentation and procurement specifications. Finally, NMC will develop the modified installation procedures for isolating fasteners on the LPD 17 Class titanium seawater piping system.
Pending successful development and qualification of the improved isolation material, these fasteners are expected to save at least 30 percent of the LPD 17 titanium piping system repair costs, which are currently estimated to be no less than $1.2M over the next five years and grow to $4.1M over the subsequent five years.
Implementation will occur within the LPD maintenance cycle, initially in the 2nd quarter FY15 at Sasebo, Japan.
Naval Surface Warfare Center, Carderock Division