Definitions of various grades of surface preparations of ferrous metals as defined by the Steel Structural Painting Council (SSPC).
surface
preparation
Brush-Off Blast (SSPC-SP7) (NACE #4)
A method in which all oil, grease, dirt, rust scale, loose mill scale, loose rust, and loose paint or coatings are removed completely. tight mill scale and tightly -adhered rust, paint and coatings are permitted to remain. However, all mill scale and rust must have been exposed to the abrasive blast pattern sufficiently to expose numerous flecks of the underlying metal fairly uniformly distributed over the entire surface.
Near White Blast (SSPC-SP10) (NACE #2)
In the method all oil, grease, dirt, mill scale, rust, corrosion products, oxides, paint, or other foreign matter have been completely removed from the surface by abrasive blasting, except for very light shadows, very slight streaks or slight discolorations caused by rust stain, mill scale oxides, or slight, tight residues of paint or coating. At least 95% of each square inch of surface areas shall be free of all visible residues, and the remainder shall be llimited to the light discoloration mentioned above. From a practical stand-point, this is probably the best quality surface preparation that can be expected today for existing plant facility maintenance work.
High and Ultra-High Pressure Water Jet Cleaning (SSPC-SP12) (Nace #5)
As part of the surface preparation, deposits of oil, grease, and foreign matter must be removed by ultra-high pressure water jetting, by steam cleaning with detergent, or by methods in accordance with SSPC-SP1. the difference in degrees of surface cleanliness is defined by the amount of pressure as follows:
Low Pressure Water Cleaning (LP WC) 34 MPa (5,000 psi)
High Pressure Water Cleaning (HP WC) 34 to 70 MPa (5,000 - 10,000 psi)
High Pressure Water Jetting (HP WJ) 70 to 170 MPa (10,000 - 25,000 psi)
Ultra-High Pressure Water Jetting (UHP WJ) Above 170 MPa (25,000 psi)
