What is Sa 2.5 blast surfacing level ? Provisions of ISO 8501-1 and IRS B1

Sa 2.5 is a standard for surface preparation in the context of blast cleaning, specifically referring to a near-white metal blast cleaning grade. According to ISO 8501-1, Sa 2.5 requires the removal of all visible oil, grease, dirt, rust, mill scale, and other contaminants, leaving the surface with a bright, uniform appearance free of any substantial contaminants. It specifies that the surface should be clean to the extent that no more than a faint shadow or a slight discoloration remains, ensuring high cleanliness for coating adhesion. IRS B1 provisions align closely with ISO 8501-1 and emphasize that Sa 2.5 is typically required for high-performance coatings, where maximum durability and resistance are critical. Both standards ensure the preparation of surfaces to a high level of cleanliness, essential for the effective application of protective coatings, particularly in harsh environments.