Although the vast majority of HRCSA project Surface Preparation is done with High Pressure Water Cleaning and/or hand tool cleaning.
It does happen, on occasion, where abrasive blasting is required (engineer specified, heavy black oxide removal, etc.). Because HRCSA is not profile dependent, the following WAB (Wet Abrasive Blast) configuration using crushed glass has proven quite popular.
Most contractors who work with HRCSA already own 7,000 psi, 6gpm, hot water high pressure water cleaners. They maximize their profits by avoiding the cost of negative air containment [1,000 gallons of fuel / day]. When specifications ask for RECOATING, wet abrasive blasting can be achieved by combining their washers with blasters. Environmentally friendly abrasion can be found with crush glass media.
The magic lies in the quality and design of the injection nozzle used.
Example of WAB (Wet abrasive blasting) using crushed glass media with pressure washer and media injection pot as per above configuration.
Field Application
Field Uses:
- Sectional coating removal [To remove lead paint in preparation for welding.]
- Can facilitate the removal of thick black oxides.
Photo: It is critical for black oxides to be removed and to mitigate the heavy concentrations of salts at the exposed steel substrate.
NOTE: Hand tools are also used to remove surface black oxides.
Be sure to remove black oxides at all interfaces.
Pack-rusted Joints: Do not blast.
NOTE: The corrosion inside a pack-rusted connections to only be high pressure water cleaned with salt remover (then blown dried with clean, dry, 100 psi air pressure). DO NOT introduce abrasives into the pack rust otherwise you will clog the capillary channels. These must remain open.