Overview
ISO 18099:2022 specifies equipment and procedures for determining the coefficient of linear thermal expansion of thermal insulating products used in building equipment and industrial installations. The method covers a broad temperature range (−196 °C to 850 °C), subject to specimen limitations, and excludes materials that undergo dimensional changes from loss of hydration water or other phase changes. The standard replaces ISO 18099:2013 and integrates EN 13471:2001.
Key topics and technical requirements
- Scope and exclusions: Applicable to insulating products when dimensional response is reversible; not for materials with phase-change or dehydration effects.
- Test principle: Measure reversible changes in linear dimension as temperature varies; report either a continuous length-vs-temperature curve or a mean coefficient between two temperatures.
- Apparatus: Typical equipment includes a dilatometer (tube/rod type, e.g., vitreous silica), micrometer calliper, calibrated thermocouples, electrical furnace (or cryogenic test chamber), and recording instrumentation.
- Specimens: Representative specimens are required - typical size (50 ± 1) mm length with 10 ± 1 mm cross section (square or diameter); surface skins/coatings removed; anisotropic products tested in relevant directions.
- Conditioning: Store specimens at (23 ± 5) °C (or (23 ± 2) °C and 50 ± 5 % RH if disputed). Tropical conditions allowed (27 ± 5 °C and 65 ± 5 % RH).
- Procedure controls: Start at reference temperature (23 ± 2 °C), limit heating/cooling rates (generally ≤ 3 K/min and ≤ 1 K/min for the last 50 °C), stabilize at intervals ≤ 50 °C until homogeneous temperature is achieved, and record reversible length changes.
- Calculation: The mean coefficient is derived from the reversible change in length divided by the reference length and the temperature difference. Instrument-specific corrections (e.g., support expansion) must be applied.
- Reporting: Test report must reference ISO 18099:2022 and include product ID, specimen preparation, conditioning, test conditions, and any deviations.
Applications and users
ISO 18099:2022 is used by:
- Manufacturers of thermal insulating products for product characterization and quality control
- Independent testing laboratories and material certification bodies
- R&D and product development teams evaluating thermal behavior
- Specifiers, engineers, and compliance officers assessing material suitability for temperature cycling in HVAC, cryogenic, petrochemical, and industrial installations
Practical benefits include accurate selection of insulation compatible with thermal cycling, reliable inputs for thermal stress and expansion calculations, and consistent test data for specifications and trade compliance.
Related standards
- EN 13471:2001 (merged into this edition)
- ISO 18099:2013 (superseded)
- Developed by ISO/TC 163 and CEN/TC 88 under the ISO–CEN cooperation (Vienna Agreement)
Keywords: ISO 18099:2022, coefficient of thermal expansion, thermal insulating products, dilatometer, linear thermal expansion testing, insulation testing.
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