A cost-effective manufacturing solution enabling the use of an alternate material in gas turbine exhaust uptakes will reduce weight and life-cycle costs on LCS. Gibbs & Cox photo
NMC investigated the use of an alternate material in a critical component on the LCS platform to address the need to reduce the structural weight.
Reducing weight on the Freedom-Class Littoral Combat Ship (LCS) is a high prioriy to meet performance objectives. One potential area for achieving weight reduction is the main gas turbine exhaust ducting (uptakes). The uptakes are currently comprised of an INCONEL® Alloy 625 interior wall that is exposed to high temperatures, a layer of thermal insulation, and a stainless steel exterior.
This NMC project employed high-speed, hot-wire gas metal arc welding (GMAW) and net-shape manufacturing approaches to reduce cost.
The project team successfully demonstrated that using an alternative material and simplified uptake wall configuration could reduce fabrication costs and 18,000 to 22,000 pounds in structural weight on LCS. To offset the higher cost of the alternative material, the project team demonstrated that high-speed, hot-wire Gas Tungsten Arc Welding (GTAW) decreased welding fabrication time. The design of the uptakes was modified to exploit the alternate material properties, further reducing part count and construction labor costs.
A full-scale section of the uptake was manufactured and delivered to Naval Surface Warfare Center, Philadelphia, for a test stand trial using a gas turbine engine where a majority of the operational profiles will be carried out. The uptake will be inspected at selected time intervals, and assuming that no damage is observed, the design will be released for manufacture and insertion on a future LCS.
StakeholderAnthony C. Smith
American Bureau of Shipping
Gibbs & Cox
Lockheed Martin Maritime Systems and Sensors
Marinette Marine Corporation
Naval Surface Warfare Center, Carderock Division
PMS 501 Littoral Combat Ship Program Office
Titanium Fabrication Corp