By improving the abrasive blasting process for structural steel on VCS, as well as the wrapping of piping similar to that shown in this mockup, the amount of construction labor needed will be reduced. NMC photo
In this project, the Navy Metalworking Center (NMC) project team conducted a series of trials to optimize the grit blasting parameters for VIRGINIA Class (SSN 774) submarines (VCS).
Proper surface preparation prior to coating application is critical for coating longevity. Grit blasting is the most common method of surface preparation in shipbuilding, and there are opportunities to make grit blasting and the associated processes more efficient.
These trials leveraged the results of previous studies and included various combinations of parameters. These parameters included variations of blast media type, blast media size, nozzle angle, and nozzle type. The project team ensured that all recommendations complied with surface cleanliness, blast profile, and pipe wall thickness requirements. The project team also looked at the associated processes of pipe wrapping and unwrapping. Shipyard procedures require that piping systems be protected when blasting nearby surfaces. The current practice is to wrap the piping, blast the surface, remove the wrapping, clean the piping, and rewrap the piping prior to painting.
The results of this project are expected to save approximately $367K per VCS hull in reduced labor, materials, and disposal cost. The majority of these savings are the result of reducing the labor associated with wrapping pipes prior to blasting in a tank. Improved processes developed by the project team are expected to reduce wrapping and unwrapping labor by 60 percent. In addition, the use of extra-long venturi nozzles in blast guns can reduce grit blasting labor by 29 percent.
Full implementation is expected to take place at General Dynamics Electric Boat (EB) by the end of 2012. Partial implementation has occurred at GDEB and at Portsmouth Naval Shipyard. In addition, Puget Sound Naval Shipyard and Huntington Ingalls Industries - Newport News Shipbuilding are evaluating project recommendations.
General Dynamics Electric Boat Corporation
Naval Surface Warfare Center, Carderock Division
Newport News Shipbuilding
PMS 450 Virginia Class Program Office