This project demonstrated that by applying improved joint preparation methods, automation techniques and work cell optimizations, the number of pipe construction labor hours can be reduced, and the cost of welding smaller diameter pipe fittings and sections could be reduced by as much as 20 percent, or 9,000 man-hours per hull.
Virginia Class Submarines (VCS) contain off-hull new construction pipe welding methods that involve complex configurations for smaller diameter pipe (< 3-inch diameter) for set-up, fit-up, fixturing, and pipe welding applications.
The Navy Metalworking Center and the Integrated Project Team developed prototype pipe fitting tools – a modified Accu-fit tool and a ball pivot tool – which reduces manual fitting needed on small diameter pipe details. NMC also developed a mobile weld fixture to be used in the welding of pipe bosses that has the potential to reduce manual welding pass times by 50%.
As a result of this effort, a 20% reduction in manual pipe fitting methods and handling of small diameter pipe will provide an increase in pipe fitting and welding automation methods which reduce the pipe labor cost by $500K per hull.
Pipe fitting tools and automation methods will be implemented for VCS hull 785 by January 2010. Several inspection and welding tools are being used at GDEB Quonset Point. The results of this project could also be applied to CVN, DDG 1000, and commercial shipyard pipe shops.