ISO 8179-2:2017

Overview

ISO 8179-2:2017 specifies a factory-applied external protective coating system for ductile iron pipes, fittings, accessories and their joints using zinc-rich paint with an overlying finishing layer (bituminous paint or compatible synthetic resin). The standard defines material composition, application methods, inspection and test procedures to ensure long-term corrosion protection of ductile iron pipeline components used in water and sewerage systems.

Key topics and technical requirements

• Coating composition: Zinc-rich paint with at least 85% zinc by mass in the dry film, followed by a finishing layer compatible with the zinc-rich paint.
• Surface condition: Substrate must be dry and free from rust, oil or non-adhering contaminants; application may be on as-cast annealed or blast-cleaned surfaces.
• Application methods: Coating may be applied by spraying or brushing; finishing layer also by spray or brush.
• Zinc-rich paint mass requirements:
  • Standard: mean mass ≥ 235 g/m² with local minimum 210 g/m².
  • Low-corrosive areas (by agreement): mean 150 g/m² with local minimum 130 g/m².
• Finishing layer thickness: mean dry film thickness ≥ 70 μm with local minimum 50 μm.
• Acceptable damage: Handling damage allowed if area < 5 cm² per m² and minor dimension ≤ 5 mm; larger defects must be repaired.
• Inspection & test methods:
  • Factory token method to determine zinc-rich paint mass (token sizes specified).
  • Dry film thickness measured directly (magnetic gauges) or indirectly on tokens.
  • Annex A describes field verification procedures; Annex B gives soil-related guidance for coating selection.
• Repairs: Permitted using zinc-rich paint meeting the same ≥85% zinc dry-film requirement.

Practical applications

ISO 8179-2:2017 is used to specify and verify external coating systems for ductile iron pipelines to protect against general and localized corrosion in buried and exposed installations. It supports:

• Asset owners and utilities specifying corrosion protection for water and wastewater mains.
• Pipe manufacturers establishing factory quality control for external coatings.
• Contractors and specifiers selecting suitable coating masses and finishing layers based on soil corrosivity.
• Inspection teams performing factory and field verification of coating mass and thickness.

Related standards

• ISO 8179-1 (metallic zinc-based coatings)
• ISO 2531 (ductile iron pipes for water)
• ISO 7186 (ductile iron products for sewerage)
• ISO 16631 (ductile iron compatible with plastic systems)

Keywords: ISO 8179-2:2017, zinc-rich paint, ductile iron pipes, external coating, finishing layer, coating mass, corrosion protection, pipeline components.