Overview
ISO/TR 10217:1989 is an ISO Technical Report (1989) that provides guidance for material selection to minimise internal corrosion in solar water‑heating systems. It discusses the parameters that influence corrosion inside closed and open circulation loops for solar hot‑water installations, and recommends design and maintenance measures to achieve durable, corrosion‑resistant systems. The report is a type‑3 Technical Report (informative) and does not cover external absorber corrosion, polymer/fluid compatibility, or safety and health issues.
Key topics
- Parameters affecting internal corrosion: fluid circulation, dissolved oxygen, aggressive ions, temperature, metal couples and material combinations.
- Materials in scope: piping, fittings, solder/weld materials and heat‑transfer fluids used inside the circuit. Absorber external surfaces and polymer compatibility are explicitly excluded.
- Functional and system characteristics: pressure resistance, thermal transfer efficiency, and resistance to extreme temperatures that influence corrosion risk.
- Causes of degradation: inappropriate design choices, material ageing in service, and inadequate maintenance.
- Recommended procedure: a two‑step approach-(1) design recommendations to define acceptable operating conditions and material/ fluid pairings (supported by tabulated guidance), and (2) maintenance recommendations to preserve these conditions over service life.
- Testing methods and ageing studies: laboratory fluid/metal screening, simulated‑service loop tests and electrochemical methods are described as ways to assess compatibility and predict performance (references to ASTM and ISO test practices are included).
- Maintenance and commissioning advice: flushing and pressure testing before filling, use of manufacturer‑recommended premixed antifreeze solutions, keeping circuits full to avoid inhibitor concentration loss, annual sampling and checks (pH, freeze point, alkalinity, metallic traces), and periodic fluid replacement in certain configurations (e.g., aluminium absorbers).
Applications
ISO/TR 10217:1989 is useful for:
- Solar thermal system designers creating absorber loops and specifying materials and fluids
- Component manufacturers (pipes, fittings, solders) defining compatibility limits
- Installers and commissioning engineers following recommended flush, fill and pressure‑test procedures
- Maintenance personnel and facility managers implementing annual checks and fluid replacement schedules
- Test laboratories evaluating fluid/metal compatibility and performing simulated service tests
Related standards
The report references and complements test methods and guidance from bodies such as ASTM and ISO (e.g., simulated‑service and screening tests, and ISO 6509 on dezincification). It should be used alongside current national and industry standards for solar thermal system durability and fluid safety.
Keywords: ISO/TR 10217:1989, solar energy, solar water heating, internal corrosion, material selection, corrosion prevention, solar thermal collectors, fluid maintenance, corrosion testing.