Sulfur dioxide is known for its aggressiveness towards steel and other metal alloys. While the compound in its pure form does not react strongly with metals, it can be highly corrosive when exposed to the moisture in the atmosphere.
ISO 6988 is an International Standard that specifies a method for assessing the resistance of materials or products to condensed moisture containing sulfur dioxide.
The method has been found to be suitable for testing metallic and non-organic coatings.
Note: For testing paints and varnishes, see BS EN ISO 3231, Paints and varnishes — Determination of resistance to humid atmospheres containing sulphur dioxide.
ISO 6988 on sulfur dioxide test on metallic and other non-organic coatings
Moist air containing sulfur dioxide quickly produces easily visible corrosion of many metals in a form resembling that occurring in industrial environments.
The method in ISO 6988 is useful for testing metallic and non-organic coatings. It provides guidance on apparatus and material, test specimens, methods of exposure, procedure, test duration, cleaning of specimens, evaluation of results, for determining the resistance of materials or products to sulphur dioxide.
The ISO 6988 test can ultimately help detect pores or other sources of weakness in protective coatings and deficiencies in corrosion resistance associated with unsuitable alloy composition or treatments.