Overview
EN ISO 22479:2022 (ISO 22479:2019) specifies a laboratory method - the sulfur dioxide test in a humid atmosphere (fixed gas method) - for assessing the corrosion resistance of metals, alloys and their coatings. Adopted by CEN and identical to ISO 22479:2019, this standard defines how to expose test specimens to a humid SO2-containing atmosphere so that SO2 dissolved in condensed moisture accelerates corrosion for comparative testing, quality control and materials evaluation.
Key topics and technical requirements
- Scope and applicability: Applies to metals and alloys, metallic and non‑organic coatings, and organic coatings for evaluation of resistance to humid atmospheres containing sulfur dioxide.
- Principle: A fixed volume of sulfur dioxide is introduced into a cabinet of fixed volume; moisture condenses on specimens and the dissolved SO2 causes corrosion.
- Test cabinet and components: Components contacting SO2 must be corrosion‑resistant and inert (must not emit vapours that influence results). Preferred cabinet capacity is (300 ± 10) L; alternative sizes are permitted if specimen arrangement, gas volume and water quantity are adjusted accordingly.
- Specimen preparation and arrangement: Standard references for panels and film thickness are cited (ISO 1514, ISO 2808). The standard covers specimen dimensions, preparation, and mounting to avoid cross‑contamination between different protection systems.
- Test cycles and duration: ISO 22479 defines required test cycles, durations and procedures for introducing water and SO2, heating the cabinet, replacing reagents, cleaning specimens after test, and performing performance checks. (Specific cycle parameters are given in the full standard.)
- Evaluation and reporting: Procedures for post‑test cleaning, assessment of corrosion damage, and required information for the test report are specified. Normative terms reference ISO 8044 (corrosion terminology).
Applications and who uses it
- Corrosion test laboratories performing standardized SO2/humidity exposure tests.
- Coatings and surface‑treatment manufacturers for product development and quality control.
- Materials engineers and R&D teams comparing corrosion resistance of alloys or coatings.
- Specification writers, purchasers and compliance officers who need standardized test evidence for materials intended for service where SO2 and humidity are concerns.
- Regulatory and standards bodies referencing harmonized test methods in procurement or product standards.
Related standards
- ISO 1514 - Standard panels for testing (paints and varnishes)
- ISO 2808 - Determination of film thickness (paints and varnishes)
- ISO 8044 - Corrosion of metals and alloys - Basic terms and definitions
- EN ISO 22479:2022 supersedes EN ISO 3231 and EN ISO 6988 (combined and revised into this edition)
Keywords: corrosion, sulfur dioxide test, humid atmosphere, fixed gas method, EN ISO 22479:2022, ISO 22479:2019, corrosion testing, metals and alloys, coatings, test cabinet.