Overview
ISO 13479:2022 specifies a standardized test method for slow crack growth on notched polyolefin pipes used for the conveyance of fluids. The method measures resistance to crack propagation by recording time to failure during a hydrostatic pressure test on pipes with machined longitudinal external notches. It is applicable to pipes with a wall thickness greater than 5 mm and is widely used to assess long-term performance of polyolefins such as polyethylene (PE).
Key topics and technical requirements
- Test principle: A pipe with four equally spaced longitudinal notches is pressurized hydrostatically while immersed in water at 80 °C; time to failure or the test period is recorded.
- Test pieces & dimensions: Minimum free length is typically (3 · dn ± 5) mm between end caps; for dn > 315 mm a minimum free length of ≥ 1 000 mm may be used where practical. Mean outside diameter and wall thickness are measured per ISO 3126.
- Notch machining: Notches are machined using a specified milling procedure. The standard calls for a 60° double equal angle V‑cutter with a controlled cutting rate of (0.010 ± 0.002) mm/r/tooth. Cutter running‑in, wear checks (after ≤100 m) and replacement (after 500 m) are required to ensure reproducible notch geometry and tip radius.
- Measurements: Remaining ligament thickness (δ_lg), notch depth, notch length and notch tip radius are defined and measured. A maximum notch radius requirement was added in the 2022 revision to reduce variability.
- Accelerated testing: Annex D provides a normative accelerated notched pipe test (ANPT) using an external detergent (example: Arkopal N100) to speed up crack propagation for PE 100‑RC materials.
- Test control: Hydrostatic stress, test pressure and test period are set by the referencing specification; clauses reference ISO 1167‑1/2 for pressure‑testing procedures and end caps.
Applications and who uses ISO 13479:2022
- Pipe manufacturers for material development, production control and demonstrating resistance to slow crack growth.
- Independent test laboratories for standardized qualification and comparative testing.
- Specifiers, utilities and infrastructure owners (water, gas, sewage) to verify long‑term durability of polyolefin piping systems.
- R&D and failure analysis teams assessing notch sensitivity, material grades (e.g., PE, PE 100‑RC) and effects of machining and test conditions.
Related standards
Keywords: ISO 13479:2022, polyolefin pipes, slow crack growth, notched pipe test, hydrostatic pressure test, ligament thickness, notch machining, ANPT, PE 100‑RC.
Open preview (PDF)Polyolefin pipes for the conveyance of fluids — Determination of resistance to crack propagation — Test method for slow crack growth on notched pipes