Re profiling of blast cleaned surfaces blast cleaned

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Re-profiling of blast cleaned surfaces. Blast cleaned surfaces that are subsequently ground do not need to be re- profiled to achieve effective coating performance. A small study undertaken by the SSPC has shown that steel which has been blast cleaned, ground and recoated performed as well in salt fog tests as steel that had been re- profiled and recoated. Maintenance painting . Maintenance painting can consist of four options: ! Spot painting ! Spot painting and full topcoat ! Total removal and repaint ! Zone painting Where the surface is contaminated with marine salts or other contaminants, the surface to be coated should be washed or, if necessary, power washed to remove all contaminants before any other cleaning operations are begun. At the beginning of the surface cleaning preparation stage of the project, the paint applicator shall clean and prepare a minimum two foot by two foot area to demonstrate that the proposed methods will obtain the speci- fied surface preparation requirements. This area shall be preserved for reference purposes during the surface preparation stage for the remainder of the project. Spot painting. Where only spot painting of corroded areas is specified, all areas of loose paint shall be removed and the bare steel cleaned to the condition specified or required by the manufacturer and equivalent to SSPC- SP1, Solvent Cleaning, SP6 for abrasive blast cleaning, SP2 for hand tool cleaning, SP3 for conventional power tool cleaning, and/or SP11 for special power tool cleaning. Primers requiring a bare metal profile may be cleaned by abrasive blast cleaning SSPC-SP6 or by needle guns and rotary peening tools to SSPC-SP11. Care must be exercised when spot blasting to avoid damaging the intact coating around the blasted areas. This may require use of low-angle blasting and small particle size abrasives. Interfaces (edges) between the existing intact coating and the cleaned area may be feathered to provide a smooth coating for spot priming. Several coating systems do not require feathering (such as polyurethane moisture-cured systems). The bare steel areas shall have an ideal surface profile of 1 mil (25 microns) to 3 mils (76 microns). However, corroded areas will generally be rougher than this, which must be considered in selection of the paint system to prevent early rust-through at the profile peaks. Surface preparation procedures may need to be modified to prevent early rust breakthrough. Paint that is to remain in place around the corroded areas shall be thoroughly cleaned by washing, and roughened, if necessary, by sandpaper or power tools to ensure adhesion of the new paint. The surface of each coat to receive a subsequent coating shall be clean, dry and prepared in accordance with the manufacturer's recommendations.
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  • Fall '19
  • Structural steel

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