Overview
ISO 10471:2018 specifies a laboratory test method to determine, 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 procedure immerses horizontally supported pipe test pieces in water, applies a constant diametral compressive load and records progressive ring deflection until failure. Results are converted to bending strain and extrapolated to an agreed service life using regression procedures.
Key topics and requirements
- Scope: Long‑term ultimate ring bending strain and relative ring deflection of GRP pipes under wet conditions; two loading methods are allowed - bearing plates or beam bars.
- Test principle: Constant vertical compressive force applied while the pipe is immersed; measure vertical deflection vs time until structural failure.
- Loading surfaces:
- Plates: minimum width 100 mm, length at least equal to test piece; used for deflections up to ~28%.
- Beam bars: flat face width 15–55 mm, required when deflection is expected to exceed 28% (at least one beam bar must be used).
- Measurements and instrumentation:
- Vertical deflection monitoring; waterproofed strain gauges may be used to measure bending strain directly.
- For accurate failure times and deflections, automatic recording is recommended for short‑life, high‑force tests.
- Data processing:
- Convert ultimate relative vertical deflection (y/dm) to ultimate bending strain using the strain factor and appropriate formulae for crown/invert or spring‑line failures.
- Use regression and extrapolation procedures (see ISO 10928) to determine long‑term values at a specified time x.
- Test parameters to be specified by referring standard: extrapolation time x, test temperature, number and length of test pieces, water pH and distribution of times to failure.
- Reporting: Test report must include loading method, dimensions, test conditions, failure mode and extrapolated long‑term strain/deflection results.
Applications and users
- Manufacturers of GRP pipes for wastewater, drainage and buried applications use ISO 10471:2018 for product development and qualification.
- Independent testing laboratories and quality assurance departments apply the method to demonstrate long‑term mechanical performance in wet service conditions.
- Specifiers, engineers and regulators use the results for structural design inputs, service life assessments and compliance with product standards.
- Useful where long‑term bending performance and ring stiffness degradation in wet environments are critical to safety and durability.
Related standards
- ISO 10928 - regression analysis and extrapolation methods for long‑term properties.
- ISO 7685 - determination of initial specific ring stiffness for GRP pipes.
- ISO 3126 - measurement of pipe dimensions.
Keywords: ISO 10471:2018, GRP pipes, glass‑reinforced thermosetting plastics, long‑term bending strain, ring deflection, wet conditions, test method, beam bars, bearing plates, ISO 10928.
Open preview (PDF)Glass-reinforced thermosetting plastics (GRP) pipes — Determination of the long-term ultimate bending strain and the long-term ultimate relative ring deflection under wet conditions