Rust is having important role to finalaise the surface preparation for steel structure before painting. Four Rust grades, designated A, B, C and D respectively, are specified. The rust grades are defined as follows
Grade-A : It is mainly adhering mill scale, but little rust
Grade-B : It is rusting and flaking of mill scale has begun
Grade-C : The mill scale is rushing away, with slight pitting
Grade-D : The mill scale has rusted away, with general pitting
Rust Grade photographs are as follows
Steel Surface largely covered with adhering mill scale but little, if any, rust.
Steel Surface which has begun to rust and form which the mill scale has begun to flake.
Steel Surface on which the mill scale has rusted away or from which it can be scraped, but with slight pitting visible under normal vision.
Steel Surface on which the mill scale has
rusted away and on which general pitting is visible under normal vision.