Standards

BS 7079 Part Al 1989 and the ISO Standard 8501 Part 11988 grade steel according to the level of millscale present on the surface. This level influences the standard of preparation and can affect the choice of the coating system.

These are the accepted standard rust grades and the system of names in this guide aligns to that standard:

Grade A Steel

Surface is covered completely with adherent millscale and with little if any rust.

Grade B Steel

Surface which has started to rust and from which the millscale has begun to flake.

Grade C Steel

Surface on which the millscale has rusted away or from which it can be scraped but with little pitting visible to the naked eye.

Grade D Steel

Surface on which the millscale has rusted away and on which considerable pitting is visible to the naked eye.