The most thorough abrasive blast cleaning standard, SSPC-SP 5/NACE No. 1, the counterpart of Sa 3 in ISO 8501-1. The surface must be free of all visible oil, grease, dirt, mill scale, rust, old coating and staining, with a uniform gray-white metallic color. It is specified for severe immersion service and some tank linings, but it is slow and costly, and flash rust can form within hours if the steel is left uncoated.
Lining spec is white metal blast, so any shadow of staining in the pits gets blasted again.
Also heard as
- SP 5
- NACE No. 1
- Sa 3
- white metal
Related terms
Near-white blast
Blast grade allowing light shadows or stains on no more than 5 percent of the surface, the usual immersion standard.
Anchor profile
Peak-to-valley roughness that blasting cuts into steel so a coating can grip, given in mils or microns.
Flash rust
Thin, quick layer of rust that forms on freshly blasted or water-washed steel within minutes to hours.
Soluble salts
Invisible chloride, sulfate and nitrate contamination on steel that causes blistering and early coating failure.