This Swedish Standards document is in three (3) sections
Section 2 = An Outline Of The Start Condition
This standard refers to surfaces of hot-rolled steel, in four different states /rust grades (A, B, C and D).
In the instances that follow, the surfaces are prepared to the four grades of surface quality (Sa 1, Sa 2, Sa 2.5 and Sa 3) by blasting with various abrasives.
A steel surface originally corresponding to rust grade B which has been prepared by blast cleaning to preparation grade 2½ is designated B Sa 2.5.
The standardised rust and preparation grades are defined by colour prints representing full scale view of a part of a surface.
- A Grade - Steel surface covered completely with adherent mill scale and with little if any rust.
- B Grade - Steel surface which has begun to rust and from which the mill scale has begun to flake.
- C Grade - Steel surface on which the mill scale has rusted away or from which it can be scraped, but with little pitting visible to the naked eye.
- D Grade - Steel surface on which the mill scale has rusted away and on which considerable pitting is visible to the naked eye.
[caption id="attachment_1957" align="alignnone" width="300"] Steel Grade A - Almost completely covered with mill scale with very little rust or oxidisation and without pitting[/caption]
[caption id="attachment_1959" align="alignleft" width="300"] Steel Grade B - A steel that has been exposed to the elements, shows signs of surface rust but with a remaining high degree of mill scale[/caption]
[caption id="attachment_1960" align="alignnone" width="300"] Steel Grade C - A steel that has been exposed to the elements, rust has formed; little if any mill scale remains and has been detached from the surface. Surface pitting has clearly started[/caption]
[caption id="attachment_1961" align="alignnone" width="300"] Steel Grade D - A steel that has been exposed to the elements for some considerable time; it shows pitting and rust inclusions. No mill scale remains due to the expansion of the surface oxidisation[/caption]