Preparation of steel substrates before application of paints and related products - Visual assessment of surface cleanliness - Part 1: Rust grades and preparation grades of uncoated s
This Part of GB/T 8923 specifies a series of rust grades and preparation grades of steel surfaces (substrate) (see Chapters 2 and 3, respectively). The various grades are defined by written descriptions together with photographs that are representative examples as described in words.
It is applicable to hot-rolled steel surfaces prepared for painting by methods such as blast-cleaning, hand and power tool cleaning and flame cleaning, although these methods rarely lead to comparable results. Essentially, these methods are intended for hot-rolled steel, but blast-cleaning methods, in particular, could also be used on cold-rolled steel of sufficient thickness to withstand any deformation caused by the impact of the abrasive or the effects of power tool cleaning.
This Part is also applicable to steel substrates (surface) that show residues of firmly adhering paint and other foreign matter (see Note 1 in 3.1) in addition to residual mill scale.
Note: The preparation grades of previously painted steel surfaces after only localized removal of paint coatings form the subject of ISO 8501-2.
This Part relates the cleanliness of the surface to its visual appearance. In many instances, this is sufficient for the purpose but for coatings likely to be exposed to severe environments, such as water immersion and continuous condensation conditions, consideration should be given to testing for soluble salts and other invisible contaminants on the visually clean surface by the physical and chemical methods which form the subjects of the various parts of ISO 8502. The roughness characteristics of the surface should also be considered by reference to the various parts of ISO 8503.
1 Scope
2 Rust Grades
3 Preparation Grades
4 Procedure for Visual Assessment of Steel Substrates
5 Photographs
Appendix A (Informative) Representative Photographic Examples of the Change of Appearance Imparted to Steel when Blast-cleaned with Different Abrasives
Appendix NA (Informative) Comparison List of the International Standards and Their Corresponding National Standard Applying to Steel Surface Treatment Before the Application of Coating and Related Products
References
