Overview
ISO 13268:2022 specifies a laboratory test method to determine the initial (short‑term) tangential ring stiffness of thermoplastic shafts or risers used in inspection chambers and manholes for non‑pressure underground drainage and sewerage systems. The second edition (2022) updates definitions, normative references and test calculations and replaces ISO 13268:2010. It clarifies when the ISO 9969 ring stiffness method applies and defines modified procedures for irregular, square or rectangular cross‑sections.
Key topics and requirements
- Scope: Test method for ring stiffness of thermoplastic riser shafts for inspection chambers and manholes.
- Applicable designs: Regular (circular, symmetrical) cross‑sections use ISO 9969; irregular, square or rectangular cross‑sections use the modified procedures in ISO 13268:2022.
- Test principle:
- Regular cross‑sections: compress horizontally supported shaft between parallel plates at a constant speed and calculate stiffness from the force producing a deflection of 0.03·d (diameter).
- Irregular/square/rectangular: apply load until deflection is 2–6% of shaft dimension, using shaped bearers supporting the external profile; load rate such that required force is reached in 3–6 minutes.
- Apparatus and fixtures:
- Loading frame with rigid parallel plates or beams; V‑supports (included angle ≥ 170°) permitted.
- Bearer width limits specified by DN/ID ranges; elastomeric bearing strips of (50 ± 5) IRHD (ISO 48‑2) where smooth contact is not provided.
- Measuring devices accurate to ±1% for force/deflection and ±0.5 mm for length.
- Test pieces:
- Three test pieces per product, aged (21 ± 2) days and conditioned 24 h at ambient temperature.
- Minimum test length 300 mm (up to 1 000 mm for irregular shafts to achieve symmetry).
- Environment: Test temperature (23 ± 2) °C.
- Reporting and calculation: Procedures for force/deflection measurement, calculation of ring stiffness and reporting are defined; note that the calculation of the shape factor (S) for irregular sections was revised in this edition.
Applications and who uses it
ISO 13268:2022 is used by:
- Manufacturers of thermoplastic risers and inspection chamber components to verify product performance.
- Independent testing laboratories performing type testing and product certification.
- Design and geotechnical engineers specifying shaft stiffness for buried drainage and sewerage systems.
- Procurement and compliance teams ensuring materials meet regulatory and contract requirements.
Practical applications include product development, quality control, compliance testing and design verification for non‑pressure underground drainage and sewerage installations.
Related standards
- ISO 9969 - Thermoplastics pipes - Determination of ring stiffness (applies to regular sections)
- ISO 48‑2 - Rubber hardness testing (used for elastomeric bearing strips)
- EN 476 referenced for bearer sizing practices
Keywords: ISO 13268:2022, ring stiffness, thermoplastics shafts, risers, inspection chambers, manholes, non‑pressure underground drainage, ISO 9969, test method.
Open preview (PDF)Thermoplastics piping systems for non-pressure underground drainage and sewerage — Thermoplastics shafts or risers for inspection chambers and manholes — Determination of ring stiffness