BLAST CLEANING STANDARDS: CUTTING THROUGH THE CONFUSION?

摘要

The cleanliness of a prepared surface is perhaps the most important factor determining a the durability of a subsequent protective coating system. Standards for surface cleanliness have been available for over fifty years, but there is still confusion regarding definitions, relation between pictorial and written standards and how the standards developed in North America (Joint SSPC/NACE standards) relate to the ISO standards used in the rest of the world. Moreover, with the arrival of power tools that can produce a level of surface cleanliness similar if not equal to levels achievable by abrasive blasting, it is worth reviewing these standards. This paper looks at the various standards and levels of blast cleaning, what they really describe and how they differ from one another. Computer image analysis is used to assess cleanliness levels of the near white (very thorough) level and finds that the ISO and Joint standard levels overlap. Finally, an attempt has been made to simplify and standardise cleanliness levels, incorporating current standards.