The purpose of NSRP Project 3-96-4 was to evaluate the productivity of and areas of hydroblast (water-jetting) removal of coatings on representative areas of a ship, such as the hull, non-skid decking areas, tanks, complex geometry using open and closed loop systems.
These procedures include surface cleanliness, surface contamination, coating removal rates, visual appearance, flash rust, and waste collection.
For the purposes of this report, the term “hydroblasting” in the abstract is used to connote the removal of coatings by using high pressure or ultra-high pressure water.
The current SSPC-SP 12/NACE 5 standard on water-jetting (prepared by NACE/SSPC Joint Task Group D on Surface Preparation by High Pressure Water-Jetting) uses the term “water-jetting” to connote coating removal by water at pressures above 10,000 psi.
Determination Of Test Procedures And Standards For Evaluation Parameters (Task 3) During production runs of the various hydroblasting equipment, various parameters were evaluated.
In most cases initial values were determined.
The first group of data (Graph 2), “USS Duluth (ballast tank)” were production rates from the hydroblasting of ballast tank 8-84-4-W.
The specification for the blasting of this tank was to spot blast to bare metal all corroded areas and sweep blast all other areas in order to remove staining, and provide a clean, profiled surface for subsequent coating adhesion.
Inboard Immersion 950 60% primer to steel, 40% cohesive in adhesive All final (after blast) adhesion values had high adhesion values.
Comparing the initial and final “Mode of Failures” for the four locations in the ballast tank where adhesion increased, the mode of failure with respect to the topcoat decreased.
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