Overview
EN ISO 8502-9:2020 - "Preparation of steel substrates before application of paints and related products - Tests for the assessment of surface cleanliness - Part 9" specifies a field method for the conductometric determination of water-soluble salts on steel substrates. The standard defines how to extract salts that form electrolytes in water and measure the electrical conductivity of the extract to report the surface density of total water‑soluble salts (reported as one combined value). It was published in 2020 and supersedes earlier editions.
Key topics and requirements
- Scope and limitation
- Measures only water‑soluble ionic contaminants (electrolytes) such as chlorides and sulphates; individual ion concentrations (e.g., Na+, Cl−) cannot be determined by this method.
- Results represent the portion of soluble salts removed by the extraction; complete removal is not guaranteed.
- Principle
- Dissolve surface salts into a defined volume of solvent (usually water), measure conductivity with a conductometer, and convert conductivity to a surface density (mass per unit area).
- Apparatus and materials
- Conductometer, beaker, sampling tools (patches or sleeves), syringe, and calibrated solvent.
- Procedure highlights
- Calibration of conductometer, equipment blank test, controlled sampling (patch or sleeve per ISO 8502-6), conductometric measurement, and prescribed calculations (corrected volume, total salt amount).
- Documentation and QA
- Test report content, accuracy statement, and reference to extraction patch sizes (e.g., standard patch and flexible sleeve methods per ISO 8502-6).
Practical applications
- Pre‑paint inspection and quality control after surface preparation of steel (bridges, offshore structures, petrochemical tanks, pipelines).
- Acceptance testing to reduce coating failures (blistering, underfilm corrosion) caused by soluble salt contamination.
- Troubleshooting coating problems and verifying cleaning or blasting effectiveness.
- Field surveys and routine maintenance checks where rapid, on‑site assessment of surface cleanliness is needed.
Who uses this standard
- Coating specifiers and consultants
- Corrosion engineers and asset owners
- Surface preparation and painting contractors
- Third‑party inspectors and testing laboratories performing on‑site salt testing
- Maintenance planners in infrastructure, marine and industrial sectors
Related standards
- ISO 8502 series (other parts for surface cleanliness testing)
- ISO 8502-6 (Bresle patch / extraction patch methods) - used in conjunction with this method for sampling
- ISO 8501 and ISO 8503 (visual cleanliness and surface profile standards)
Keywords: EN ISO 8502-9:2020, conductometric determination, water‑soluble salts, surface cleanliness, steel substrates, field method, Bresle patch, ISO 8502.
