ISO 13477:2008

Overview

ISO 13477:2008 specifies the small‑scale steady‑state (S4) test method for assessing resistance to rapid crack propagation (RCP) in thermoplastics pipes used for the conveyance of fluids. The S4 test determines whether a longitudinal crack initiated by impact at a specified temperature and internal pressure will arrest or propagate. It is applicable to thermoplastics pipes intended for the supply of gases or liquids (air may be present in liquid services). Note: the method was developed for monolayer pipes; applicability to multi‑layer/coated pipes is under study.

Key topics and technical requirements

• Test principle: A conditioned pipe section is pressurized with a compressible fluid and impacted near one end to initiate a fast longitudinal crack. Decompression is retarded by internal baffles and an external containment cage to produce steady‑state RCP in a short specimen.
• Apparatus essentials:
  • Containment cage limiting radial expansion (rings concentric with pipe; max diameter ≈ (1.1 ± 0.04)d).
  • Decompression baffles with specified diameter and pitch to slow gas decompression.
  • Striker blade geometry and anvil to control crack initiation (blade length ≈ 0.40d; striker velocity ≈ 15 ± 5 m/s).
  • Pressure instrumentation (±2% accuracy).
• Specimen and conditioning:
  • Gauge length > 5d; test piece length 7d to 8d.
  • Conditioning temperature (Tcond) related to test temperature (T) by Tcond = 1.12·T − 2.8 °C; conditioning time per ISO 1167‑1.
  • Crack initiation must follow within (180 ± 20) s of removal from conditioning.
• Test procedure & interpretation:
  • Series of tests at constant temperature and varying pressures (or vice versa) to determine critical pressure or critical temperature (Annex A/B).
  • Crack arrest: crack length lc < 4.7d; propagation: lc ≥ 4.7d.
• Reporting: Test report must cite ISO 13477, test pipe ID, polymer, diameter/series, gauge length, temperatures, pressures, crack lengths, striker mass/speed, and notable incidents.

Applications and users

ISO 13477:2008 is used for:

• Material qualification and product development of thermoplastics pipes (e.g., polyethylene).
• Type testing and performance verification for gas and water distribution systems where RCP resistance is critical.
• Manufacturers, independent testing laboratories, specification writers, utilities, and regulators who need standardized, repeatable RCP assessment to inform design, safety margins and compliance.

Keywords: ISO 13477:2008, S4 test, RCP test, thermoplastics pipes, rapid crack propagation, pipe testing, polyethylene RCP.

Related standards

• ISO 161‑1 - Nominal diameters and pressures (metric)
• ISO 1167‑1 - Determination of resistance to internal pressure (conditioning)
• ISO 3126 - Dimension determination for plastics piping components
• ISO 11922‑1 - Dimensions and tolerances (metric series)

This ISO standard provides a practical, repeatable S4 test method to evaluate RCP behavior, supporting safer design and specification of thermoplastic piping systems.