Advanced Metalworking Solutions for
Naval Systems that Go in Harm's Way

Large Diameter Pipe Process Improvements

Improved pipe processing methods to result in more than $500K savings per VCS hull. NMC photo


This Navy Metalworking Center (NMC) project developed several improved fixturing and positioning methods, as well as work cell automation techniques.


Current VIRGINIA (SSN 774) Class submarines (VCS) contain off-hull new construction pipe welding details consisting of complex configurations of large diameter pipe (3"-12" diameters) that require detailed preparation, fixturing, positioning, fit-up, and welding. Current fabrication techniques and weld processes require significant labor to set-up and process these assemblies, reducing work cell process flow output and efficiencies.

Technical Approach

Specifically, the project team is developing several automation methods for specific areas of pipe preparation including fixturing, positioning, and fitting; pipe boss methods; enhanced welding; as well as the use of internal pipe joint blending tools. These improvements will reduce pipe section cutting, rework, and pipe material scrap.


Projected savings are currently estimated to be 8,500 man-hours per hull in manual labor. This man-hour savings, multiplied by the conservative hourly rate of $65 per hour, results in a projected $552K per hull savings and $5.5M savings over the next 10 VCS planned hulls in the FY13-FY17 period.


The project team developed several automation methods for pipe preparation including fixturing, positioning, and fitting; pipe boss welding and machining; and internal pipe joint blending tools. Prototype process improvements were tested and validated in both General Dynamics Electric Boat and Huntington Ingalls Industries - Newport News Shipbuilding pipe shops in Q3/Q4 FY2011. Full implementation is expected in both VCS pipe shops for the SSN 788 hull in the fall of 2012.




Dave Hart
Life Cycle Engineering


General Dynamics Electric Boat Corporation
Naval Surface Warfare Center, Carderock Division
Newport News Shipbuilding
PMS 450 Virginia Class Program Office