ISO 10952:2021

Overview

ISO 10952:2021 specifies a standardized test method to determine the chemical resistance of glass-reinforced thermosetting plastics (GRP) pipes and fittings (nominal sizes DN 100 and larger) when subjected to a deflected condition. Used together with ISO 10928 (regression analysis methods), ISO 10952 evaluates how a chemical environment affects the interior of a pipe or fitting over a specified time. The document addresses accelerated effects caused by strain from deflection - commonly referred to as strain corrosion.

Key topics and technical requirements

• Scope: Test method for GRP pipes and fittings DN 100+ in a diametrically deflected condition; interior exposed to a corrosive test liquid.
• Test principle: Rings (complete pipe sections) are held in a fixed deflection, exposed internally to test liquid at specified temperature, and time-to-leak (or spring-line failure) is recorded at multiple deflection/strain levels to enable extrapolation.
• Test pieces: Rings cut from pipe or fitting with smooth, perpendicular ends; longitudinal reference lines on the inside; sample lengths and counts set by the referring standard (minimum data for regression: at least 18 data points).
• Measurements and apparatus:
  • Loading frame to maintain constant deflection.
  • Dimensional measuring devices calibrated to ±1.0 % for length, diameter, wall thickness and vertical diameter change.
  • Optional strain gauges (foil type) for direct strain measurement; gauge lengths recommended for typical diameters.
• Dimensional determinations: Mean wall thickness measured at six locations; mean diameter computed from internal/external diameter and mean wall thickness.
• Conditioning: Test pieces stored under testing conditions for at least 8 hours unless otherwise specified.
• Test procedure: Deflection or strain-based procedures are given; test liquid introduced between chemically inert dams (25–50 mm depth) within 2 hours of deflection; containment measures for fragmentation/leakage required.
• Data and extrapolation: Distribution requirements for failure times (to ensure statistical validity) and use of regression analysis (ISO 10928) to calculate extrapolated deflection/strain for specified service life.

Applications and users

ISO 10952 is essential for:

• GRP pipe and fitting manufacturers validating chemical resistance under realistic strain conditions.
• Design engineers and material specialists evaluating susceptibility to strain corrosion.
• Test laboratories performing standardized accelerated aging/chemical resistance tests.
• Asset owners and specifiers in chemical processing, wastewater, industrial piping, and infrastructure where GRP is used and chemical exposure plus mechanical deflection may coexist.

Related standards

• ISO 10928 - Methods for regression analysis and their use (referenced for extrapolation).
• ISO 23856 - References ISO 10952 for related testing contexts.

Keywords: ISO 10952:2021, GRP pipes, glass-reinforced thermosetting plastics, chemical resistance testing, strain corrosion, deflected condition, pipe testing, ISO 10928, strain gauges, DN 100.