ISO 24690:2025

Glass reinforced thermosetting plastic (GRP) pipes - Test method for the determination of long-term pressure endurance strength

This document specifies a method for determining the long-term pressure endurance of glass-reinforced thermosetting plastics (GRP) pipes, based on the residual failure strength of test pieces after ageing for a specified time at specified internal pressure and temperature. The internal environment is specified in the referring standard. The external environment can be air or water.

Tubes en plastiques thermodurcissables renforcés de verre (PRV) — Méthode d'essai pour la détermination de la résistance d'endurance à la pression à long terme

General Information

• Status: Published
• Publication Date: 02-Oct-2025
• ICS: 23.040.20 - Plastics pipes
• Technical Committee: ISO/TC 138/SC 6 - Reinforced plastics pipes and fittings for all applications
• Drafting Committee: ISO/TC 138/SC 6/WG 1 - Methods of test
• Current Stage: 6060 - International Standard published
• Start Date: 03-Oct-2025
• Due Date: 19-Apr-2026
• Completion Date: 03-Oct-2025

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.

Standards Content (Sample)

International
Standard
ISO 24690
First edition
Glass reinforced thermosetting
2025-10
plastic (GRP) pipes — Test method
for the determination of long-term
pressure endurance strength
Tubes en plastiques thermodurcissables renforcés de verre
(PRV) — Méthode d'essai pour la détermination de la résistance
d'endurance à la pression à long terme
Reference number
© ISO 2025
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Apparatus . 2
5.1 Measuring devices .2
5.2 End sealing devices.2
5.3 Supports .3
5.4 Container .3
5.5 Pressurising system .4
5.6 Pressure measuring device .4
5.7 Electric resistance meter .4
5.8 Strain measuring device(s) .4
6 Test pieces . 4
6.1 Number .4
6.2 Free length .4
6.3 Cutting . .4
7 Conditioning . 4
8 Procedure . 4
8.1 Temperature .4
8.2 Dimension measurements . .4
8.3 Strain measurements .4
8.4 Sealing .5
8.5 Aging pressure . .5
8.6 Failure pressure .5
9 Detection of failure . 5
9.1 General .5
9.2 Detection methods .6
9.2.1 Loss of test liquid .6
9.2.2 Drop in electrical resistance . .6
10 Test report . 6
Bibliography . 7

iii
Foreword
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This document was prepared by Technical Committee ISO/TC 138, Plastics pipes, fittings and valves for the
transport of fluids, Subcommittee SC 6, Reinforced plastics pipes and fittings for all applications.
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iv
Introduction
This test method is an alternative to other methods to determine long-term pressure performance of glass
reinforced plastic pipes. The method removes the unpredictability of time to failure of specimens subject to
constant pressure.
The main difference is that all specimens are aged at a constant internal pressure and temperature, and
at a series of specified times individual specimens are loaded to short-term failure as a measure of their
residual strength. When all the specimens have been tested, the residual strength is extrapolated over time
to determine long-term
...