Surface treatment in which steel grit, sand, or other abrasive material is blown against an object to produce a roughened surface or to remove dirt, rust, and scale.
Abrasive-Blasting is the operation of forcibly propelling a stream of abrasive material against a surface under high pressure to smooth a rough surface, roughen a smooth surface, shape a surface, or remove surface contaminants. A pressurized fluid, typically air, or a centrifugal wheel is used to propel the media.
Common abrasives used include:
- Steel shot
- Steel grit
- Glass bead
- Crushed glass
- Aluminum oxide
- Silicon carbide
- Plastic
- Walnut shell
- Corn cob
- Baking soda
- Ceramic grit
- Copper slag
The table below gives a summary of the different qualities in surface preparations used by some standards.
Description | Swedish SIS 05 5900 | American SSPC-SP | International ISO-8501-1 |
---|---|---|---|
White metal | Sa 3 | SSPC – SP 5 | Sa 3 |
Near white metal | Sa 2½ | SSPC – SP10 | Sa 2½ |
Commercial blast | Sa 2 | SSPC – SP 6 | Sa 2 |
Brush-off blast | Sa 1 | SSPC – SP 7 | Sa 1 |
Power tool cleaning | St 3 | SSPC – SP 3 | St 3 |
Hand tool cleaning | St 3 | SSPC – SP 2 | St 2 |
Initial condition of steel as per ISO 8501-01.
Rust grade | Pictorial example | Description |
---|---|---|
A | Steel covered completely with adherent mill scale and with, if any, little rust. | |
B | Steel surface which has begun to rust and from which the mill scale has begun to flake. | |
C | Steel surface on which the mill scale has rusted away or from which it can be scrapped, but with little pitting visible to the naked eye. | |
D | Steel surface on which the mill scale has rusted away and on which cosiderable pitting is visible to the naked eye. |
Pictorial examples of surface preparation according to ISO 8501-01
Cleaning standard | Initial steel condition | |||
---|---|---|---|---|
A | B | C | D | |
St2 – Hand tool cleaning | Not applicable | |||
St3 – Power tool cleaning | Not applicable | |||
Sa1 – Brush-off blast | Not applicable | |||
Sa2 – Commercial blast | Not applicable | |||
Sa2.5 – Near white metal | ||||
Sa3 – White metal |