In this article we aim to raise awareness of the steel surface manual preparation standards commonly used in the UK and Europe. Elsewhere NACE and SSCP are often referred to and these will be addressed and compared in an upcoming publication.
As you may have already read in our Steel Surface Cleanliness blog, BS EN ISO 8501-1:2007 is a visual assessment of surface cleanliness that specifies a series of rust grades and preparation grades of steel surfaces. The various grades are defined by written descriptions together with photographs that are representative examples within the tolerance of each grade as described by words and summarised below.
A) Steel surface largely covered with adhering mill scale but little, if any, rust.
B) Steel surface which has begun to rust and from which the mill scale has begun to rust.
C) 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.
D) Steel surface on which the mill scale has rusted away and on which general pitting is visible under normal vision.
Note: Although listed here and in the standard, rust grade A is not achievable by manual preparation methods.
Surface preparation by hand and power tool cleaning (such as scraping, wire-brushing, machine-brushing and grinding) is designated by the letters “St”.
Prior to hand and power tool cleaning, any heavy layers of rust shall be removed by chipping. Visible oil, grease and dirt shall also be removed.
After hand and power tool cleaning, the surface shall be cleaned from loose dust and debris.
Preparation grade St1 is not included, as it would correspond to a surface unsuitable for coating, lining or painting.
St2: Thorough hand and power tool cleaning – When viewed without magnification, the surface shall be free from visible oil, grease and dirt, and from poorly adhering mill scale, rust, paint coatings and foreign matter.
St3: Very through hand and power tool cleaning – As for St2, but the surface shall be treated much more thoroughly to give a metallic sheen arising from the metallic substrate.
Achieving The Right Finish
We offer a bespoke steel surface preparation service based on the starting condition of your steel surface and the required preparation grade. We use a variety of tools to achieve these results in the fastest and most cost-effective way.
For more information about our surface preparation, coating, lining and painting services, please call 01274 721188 or email email@example.com.