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ASSESSMENT OF DEGREE OF REMOVAL OF RUST, MILL SCALE AND OTHER VISUAL CONTAMINANTS (INSPECTED WITHOUT MAGNIFICATION).
Important Note: Surface cleanliness is not a measure of surface profile – see the following pages for notes on surface profile.
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Surface Preparation Grades of Blast Cleaned Steel
Explanatory Details |
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Rust Grade ASteel with the millscale layer intact and very minor, or no rusting |
.Blast Class 1 (SP-7/N4)Very light, whip over blast clean with removal of loose surface contaminants. |
Rust Grade BSteel with spreading surface rust, and the millscale commenced flaking. |
Blast Class 2 (SP-6/N3)Substantial blast clean with wide spread, visible contaminant removal and base metal color appearing. |
Rust Grade CRusty Steel with the millscale layer flaked and loose, or lost, but only minor occurrence of pitting. |
Blast Class 2 ½ (SP-10/N2)Intense blast clean leaving shaded grey metal with only tiny, isolated flecks or strips of visible contaminants. |
Rust Grade DVery rusty steel with the millscale layer all rusted and extensive occurrence of pitting. |
Blast Class 3 (SP-5/N1)Complete blast clean with consistent, metal color all over and no visible contaminants. |
DISCLAIMER: The grades of rust and blast cleaned surfaces ‘information’, described and illustrated on these pages are a guide only and do not claim to be approved nor complying nor substitutable for or by any surface preparation standard. It is responsibility of the reader and/or users of this ‘information’ to separately determine and verify the specifications and/or methods and/or assessment of surface preparation as indicated or directed or required by or in any work specifications or standards. Blast-One™ expressly disclaims any liability for the use or misuse of this ‘information’.
