Overview
ISO 18468:2017 specifies requirements and test methods for factory-applied epoxy coatings (fusion bonded epoxy powder or 2‑pack liquid epoxy) used on ductile iron fittings, accessories, joints and valves supplied to ISO 2531 and ISO 7186. The standard covers internal and external coatings for the conveyance of raw water, potable water and waste waters at operating temperatures up to 60 °C, and defines both routine production tests and performance tests to verify coating quality.
Key topics and technical requirements
- Coating types: Fusion bonded epoxy or two‑pack liquid epoxy applied in factory conditions.
- Surface preparation: Blasted surfaces must meet ISO 8501‑1 Class Sa2.5 and dust levels per ISO 8502‑3 (≤ Rating 3).
- Appearance: Coating must be uniform in colour and smooth, free from visible defects (pinholes, blisters, wrinkles). Minor chalking and repair colour variation allowed.
- Thickness:
- Localized minimum (general): > 200 µm
- Minimum average (general): ≥ 250 µm
- Designated zones (e.g., joint areas): localized min 150 µm
- Adhesion: Pull‑off test (ISO 4624) average ≥ 8.0 MPa and minimum single value ≥ 6.0 MPa. Alternative: cross‑cut knife test (Annex B) with rating ≤ level 2.
- Cross‑linking: Assessed by MIBK wipe test or ΔTg method; ΔTg ≤ 5 °C when used.
- Non‑porosity (holiday test): No electrical puncture at 1 500 V (does not apply to designated zones).
- Performance tests: Impact resistance (no holidays permitted) and resistance to hot water (adhesion after hot‑water test ≥ 6.0 MPa; no cracks, blisters or disbondment).
- Repairs: Must use compatible materials and meet thickness, cross‑linking and non‑porosity requirements.
Applications and users
ISO 18468:2017 is used to ensure durable, water‑safe coatings on ductile iron products for:
- Water utilities and municipal infrastructure (potable and raw water distribution)
- Sewerage system suppliers and asset owners (wastewater conveyance)
- Manufacturers of ductile iron fittings, valves and accessories specifying factory epoxy coatings
- Coating formulators and applicators validating processes and materials
- Third‑party testing laboratories, procurement/specification engineers and compliance auditors
Implementing ISO 18468 helps reduce corrosion, prevent contamination of potable water, and standardize inspection and test regimes across production and supply chains.
Related standards
- ISO 2531 - Ductile iron pipes, fittings and joints for water applications
- ISO 7186 - Ductile iron products for sewerage applications
- ISO 4624 - Pull‑off test for adhesion
- ISO 8501‑1 and ISO 8502‑3 - Surface preparation and dust assessment
Keywords: ISO 18468:2017, epoxy coating, ductile iron fittings, fusion bonded epoxy, 2‑pack liquid epoxy, coating thickness, adhesion, holiday test, potable water, sewerage.