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Pipe Assembly Installation Improvement Methods

On-hull pipe process improvements will reduce labor-hours associated with pipe assembly and installation by 20 percent on VCS. (Electric Boat photo)


The objective of this Navy Metalworking Center project is to reduce the labor-hours of on-hull manual pipe assembly installations and associated welding processes by a minimum of 20 percent per hull (9,000 man-hours per hull).


VIRGINIA Class submarines (VCS) currently require approximately 45,000 labor hours to install piping assemblies on-hull due to extensive manual preparation, fitting, aligning and welding process steps. The Navy Metalworking Center is executing a Navy ManTech project to reduce man-hours needed for pipe assembly and installation on Virginia Class Submarines (VCS). This project is building on the success of two previous projects* that improved VCS pipe shop assembly processes for small and large diameter pipes. The current project involves increasing installation efficiencies of on-hull pipe assembly methods by using improved tooling for pipe fit-up, fixturing and positioning, and automated welding/joining processes.

*The previous projects were S2224 Pipe Preparation and Welding Methods and S2326 Large Diameter Pipe Process Improvements.


Technical Approach

Candidate tooling concepts were generated to improve methods for pipe assembly installation fit-up, fixturing, and positioning, and/or to allow for the extended use of automated welding equipment. Tooling concepts were down-selected to fabricate prototypes for bench-top testing. Initial results were used to generate second article prototypes for test and evaluation to confirm effectiveness in reducing labor time and cost.


VCS installation process improvements will decrease the cost of preparing, fitting, welding, and repairing on-hull installation pipe assemblies and details by 20 percent or greater, equivalent to 9,000 labor-hours per hull. Using a conservative hourly rate of $65 per hour equates to projected savings of $600K per ship.


Implementation is expected at both General Dynamics Electric Boat and Newport News Shipbuilding for use in the construction of SSN 788 in FY 2014. 




Charles McNamara
Asst. Program Manager for Virginia Class Development and Modernization
Naval Sea Systems Command, PMS 450D


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