NMC is conducting a Navy ManTech project to develop a user-friendly weld sequence planning tool that quickly determines the optimal weld sequence and best practices to improve acquisition affordability for Virginia Class Submarine (VCS) and Ohio Replacement (OR) platforms.
Weld-induced distortion on major ship assemblies creates a significant manufacturing challenge and impacts both cost and schedule. Currently, weld-induced distortion on major assemblies such as foundation tanks, bulkheads, and box girders on VCS is addressed by trial and error and the application of trade experience during the fabrication process. This methodology results in substantial labor hours, rework, and a lack of repeatability hull to hull. Software packages are available to do this work; however, even an experienced analyst can take days or weeks to arrange, run, and obtain results from detailed weld analysis. The lack of a tool that can be easily integrated into existing manufacturing and shop floor systems will require the use of the same trial-and-error process on OR, ultimately presenting trades with the same issues encountered with VCS.
General Dynamics Electric Boat (EB) estimates a $3.87 million cost savings over five years for VCS and $580,000 per OR hull through reduced trial-and-error weld sequencing, mitigation of weld-induced distortion in the final product, and improved throughput. This solution also has the potential to impact all platforms that experience weld distortion (CVN, LHA, DDG, LPD, etc.), which could result in significant long-term cost savings.
The Integrated Project Team (IPT) will work with multiple commercialization partners to develop a prototype weld sequence planning tool that will be incrementally enhanced; the final tool will be validated with experimental distortion data on a common major VCS / OR assembly. The tool is expected to be implemented on SSN 796 starting in the third quarter of FY16 at EB.
General Dynamics Electric Boat Corporation
Naval Surface Warfare Center, Carderock Division
PMS 450 Virginia Class Program Office
PMS 397 Ohio Replacement Program Office