Evaluation of “Spot and Sweep” Blasting as a Cost Effective ... - NSRP

DRAFT- PROCESS FOR SPOT AND SWEEP BLAST DEMONSTRATION1. The spot and sweep process preformed by the Chariot Robotics unit (or equivalent) may beused for all areas of the underwater-hull and freeboard on approved surface ships. For areas notprepared using the Chariot Robotics or equivalent; Ultra High Pressure (UHP) lances, abrasiveblasting, may be used to create either an SSPC SP-12 WJ-2/M surface or an SSPC SP-10 surface.SSPC SP-3 Power tool cleaning may be authorized for fairing in the spot and sweep surface asrequired.2. The contractor shall inspect the existing coating on the hull and shall determine the sequenceof the epoxy coatings currently on the hull prior to blasting. The anticipated sequence is redprimer followed by gray epoxy tie coat. The contractor shall note these colors for use inNAVSEA inspection of the hull prior to application of the first coat of epoxy primer.3. The Chariot Robotics unit (or equivalent) shall be set up to accomplish the following:(a) Remove all rust and fouling from areas of bare metal to create a SSPC SP-12, WJ-2/Msurface condition in accordance with specified NAVSEA Standard Item 009-32, FY 12 Change 1processes.(b) Remove all antifouling coating and remove approximately 1/2 of the thickness of the currentepoxy tie coat thickness from the underwater hull area.(c) Remove all silicone alkyd, regardless of coating thickness, and remove approximately 1/2 ofthe thickness of the current epoxy topcoat from the freeboard area.(d) Smoothly feather or transition from areas of bare metal to the retained epoxy primer/tie coat.Areas of sharp or "step" transition between bare metal and paint shall be noted by the NAVSEArepresentative for detailed inspection. *under review: Feather edges where the Chariot Roboticsunit (or equivalent) leave behind markings in the existing paint (concentric circle areas whichsome describe as “crop circles”).