ISO 10471:2025

Overview

ISO 10471:2025 specifies a laboratory method for determining, by extrapolation, the long‑term ultimate bending strain and the long‑term ultimate relative ring deflection of glass‑reinforced thermosetting plastics (GRP) pipes under wet conditions. The standard covers test arrangement, apparatus, specimen preparation and conditioning, measurement procedures and the use of regression/extrapolation to predict long‑term performance. Two loading approaches are provided: loading with bearing plates or with beam bars.

Key topics and technical requirements

• Scope: Measurement of ring bending strain and relative ring deflection of GRP pipes immersed in water and loaded diametrically under a constant vertical compressive force until failure.
• Loading methods: Two accepted force application surfaces - plates or beam bars - with a requirement to use at least one beam bar when relative deflection is expected to exceed 28%.
• Apparatus: Compressive loading machine, force application surfaces (plates/beam bars), water container, and measuring devices (automatic recorders recommended for fast failures).
• Specimen details: Requirements for specimen length, wall thickness and mean diameter; number of test pieces and conditioning (Clause 9 aligned with ISO 23856).
• Environment: Test water temperature and pH shall be set by the referring standard; if unspecified, default is (23 ± 5) °C and pH 7 ± 2.
• Measurement and conversion: Vertical deflection (y) is recorded; ultimate relative deflection y/dm is converted to ultimate bending strain εu,wet using the standard’s formulas or waterproof strain gauges. Neutral axis location must be considered where wall construction alters it.
• Extrapolation: Time‑to‑failure data and corresponding strains are analyzed per ISO 10928 regression methods to derive long‑term (x‑year) values εu,wet,x.
• Reporting: Test method choices (plates vs bars), test conditions, specimen geometry, and extrapolation parameters must be recorded in the test report.

Applications and who uses it

ISO 10471:2025 is intended for:

• Manufacturers of GRP pipes for product development, quality control and lifetime assessment.
• Independent test laboratories performing standardized durability testing.
• Design engineers and specifiers who need validated long‑term bending strain and ring deflection data for GRP pipe selection and structural assessments.
• Standards bodies and certification authorities requiring consistent methods for comparing GRP pipe performance.

Practical uses include verifying pipe resistance to long‑term diametral loading in wet environments and producing data for service life prediction and compliance with product specifications.

Related standards

• ISO 10928 - regression analysis and use for extrapolation
• ISO 7685 - initial ring stiffness of GRP pipes
• ISO 3126 - determination of dimensions for plastic piping components
• ISO 23856 - conditioning procedures referenced for specimen preparation

Keywords: ISO 10471:2025, GRP pipes, glass‑reinforced thermosetting plastics, long‑term bending strain, ring deflection, wet conditions, test method, extrapolation, ISO 10928.