SSPC-SP 7/NACE No. 4, Brush-Off Blast Cleaning

When viewed without magnification, the surface shall be free of all visible oil, grease, dirt, dust, loose mill scale, loose rust, and loose coating. Tightly adherent mill scale, rust, and coating may remain on the surface. Mill scale, rust, and coating are considered tightly adherent if they cannot be removed by lifting with a dull putty knife. 

Prior to blast cleaning, visible deposits of oil and/or grease should be removed by power washing or other agreed upon methods. A Brush-off Blast may also be used to abrade a previous coating, providing a surface profile for new coating application.

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