Steel Surface Cleanliness Achieved By Blast Cleaning
Abrasive blast cleaning is often referred to as grit blasting, shot blasting or sand blasting and is the most effective way of cleaning steel surfaces in preparation for subsequent NDT testing or the application of paints, coatings or linings.

Abrasive blast cleaning is a commercially beneficial alternative to hand cleaning and saves up to 75% of the time required compared to other cleaning methods. The abrasive media themselves are relatively inexpensive and in some cases can be recycled and reused for further cost savings.

In this article we aim to raise awareness of the steel surface 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.

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 and are summarised below.

Rust Grades

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.

Surface Preparation By Blast Cleaning Is Designated By The Letters “Sa”

  • Sa1: Light blast 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.
  • Sa2: Thorough blast cleaning – When viewed without magnification, the surface shall be free from visible oil, grease and dirt, and from most of the mill scale, rust, paint coatings and foreign matter. Any residual contamination shall be firmly adhering.
  • Sa2½: Very thorough blast cleaning – When viewed without magnification, the surface shall be free from visible oil, grease and dirt, and from mill scale, rust, paint coatings and foreign matter. Any remaining traces of contamination shall show only as slight stains in the form of spots or stripes.
  • Sa3: – Blast cleaning to visually clean steel – When viewed without magnification, the surface shall be free from visible oil, grease and dirt, and from mill scale, rust, paint coatings and foreign matter. It shall have a uniform metallic colour.

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, including purpose-built blast rooms and mobile blast units. Surface treatment can take place either in-house at our facility in Bradford, or on-site if required.

Find out more

For more information about our abrasive blast cleaning services, including costs and timeframes, please call 01274 721188 or email sales@kuegroup.com.