Overview
ISO 16685:2025 - Thermal insulating products for industrial installations - Mechanical properties testing at sub-ambient temperatures specifies equipment, environmental control and procedures to determine mechanical properties of thermal insulation used in industrial installations at sub-ambient temperatures from −196 °C to 25 °C. The standard requires specimens to reach a thermal equilibrium before testing and excludes products that undergo dimensional change from loss of hydration water or other phase changes during cooling.
Keywords: ISO 16685:2025, thermal insulating products, sub-ambient temperatures, mechanical properties testing, liquid nitrogen.
Key Topics and Requirements
- Scope and limits: Tests apply between −196 °C and 25 °C, subject to specimen temperature limitations; not applicable to materials that change dimensionally due to hydration loss or phase change.
- Principle: Measure shear, compression and tensile behaviour at the specified sub-ambient temperature after the specimen attains thermal equilibrium.
- Referenced test methods: Shear (ISO 16537), compression (ISO 29469), tensile strength perpendicular to faces (ISO 29765) or other appropriate standards.
- Apparatus:
- Test machine with compatible cooling system (cold chamber or cryostat).
- Displacement, force and recording devices operable at test temperature.
- Cold chamber able to maintain specimen mean temperature within ±3 °C.
- Temperature sensors (calibrated thermocouples, accuracy ±0.5 K) in good thermal contact with specimen.
- Supplementary items such as a heating ring on the machine connecting rod to limit temperature difference to ≤5 K.
- Cooling media examples: refrigeration units, gas expansion (e.g., CO2 or N2), immersion in boiling/refrigerated liquids - liquid nitrogen is commonly used (with ventilation/ safety controls due to asphyxiation risk).
- Specimens: Dimensions and conditioning per the relevant product standard; tensile specimens include Type A (tapered block), Type B (rectangular/round/square), Type C (for adhesive/bonding tests).
- Procedure: Measure dimensions, preload, cool specimen in chamber and maintain at target temperature for at least 10 minutes to reach thermal equilibrium, then perform mechanical test per reference standards.
- Reporting: Must include identification, specimen details, test method and conditions, individual and mean results, deviations and unusual observations. No accuracy statement included in this edition.
Applications and Users
Practical uses:
- Type testing and qualification of industrial thermal insulation at cryogenic or refrigerated service temperatures.
- Quality control and R&D for insulation manufacturers (PUR/PIR, cellular plastics, sandwich panels).
- Third‑party test laboratories, inspection bodies, procurement/specification teams, and plant engineers verifying material performance at low temperatures.
Who should use it:
- Test laboratories, product manufacturers, material engineers, compliance officers and designers specifying insulation for cold service.
Related Standards
For implementation, follow the referenced standards for specific test procedures, and apply appropriate safety controls when using cryogenic coolants.