Overview
ISO 24690:2025 - Glass reinforced thermosetting plastic (GRP) pipes - Test method for the determination of long‑term pressure endurance strength - specifies a laboratory method to assess the long‑term pressure endurance of GRP pipes. The method measures residual failure strength of pipe test pieces after controlled ageing under specified internal hydrostatic pressure and temperature, with the external environment being air or water. Results can be used to characterise long‑term performance and to provide data for regression analysis (see ISO 10928).
Key topics and technical requirements
- Test principle: Age pipe cut lengths at a defined internal pressure and temperature for predefined times; at each time point, load the specimen to short‑term failure to measure residual strength.
- Test pieces: Full pipe sections with smooth, perpendicular ends; free length and number of test pieces set by the referring standard.
- Aging conditions: Internal fluid and environment specified by the referring standard; external environment may be air or water. Pressure, temperature and ageing times are prescribed.
- Apparatus and accuracy:
- Dimensional measuring devices calibrated to ±1.0% (length, diameter, wall thickness) per ISO 3126.
- Pressure measuring device calibrated to ±1.0% of test pressure.
- Optional electric resistance meter able to detect resistance changes to 3 MΩ or less.
- Optional strain gauges calibrated to ±2%.
- End sealing: Fixtures that allow testing with or without hydrostatic end thrust; typical sealing arrangements are provided (internal or external seals).
- Procedure essentials: Conditioning (default 24 h in air at room temperature unless otherwise specified), avoid air entrapment, maintain ageing pressure within tolerance, record ageing duration to ±2%.
- Failure detection: Defined failure modes - bursting, leaking, weeping - and detection methods such as loss of test liquid or drop in electrical resistance.
- Data analysis: Individual residual strengths for each ageing time are analysed (ISO 10928 referenced) to extrapolate long‑term behaviour.
Applications and users
ISO 24690:2025 is intended for:
- Manufacturers and test laboratories validating long‑term hydrostatic performance of GRP piping systems.
- Design and quality engineers assessing material durability, service life prediction, and compliance with project or regulatory requirements.
- R&D teams comparing GRP formulations, reinforcements or manufacturing methods under realistic hydrostatic ageing.
Practical uses include verification of design pressure over time, selection of GRP pipes for water, wastewater and industrial fluid transport, and generation of data for lifetime regression models.
Related standards
- ISO 3126 - Measurement of pipe dimensions referenced for dimensional checks.
- ISO 10928 - Methods for regression analysis and use with GRP long‑term data.
Keywords: ISO 24690:2025, GRP pipes, long‑term pressure endurance, glass reinforced thermosetting plastics, hydrostatic ageing, residual strength, test method.
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