Overview
ISO 13478:2007 - Thermoplastics pipes for the conveyance of fluids - Determination of resistance to rapid crack propagation (RCP) - Full-scale test (FST) specifies a full‑scale test method to determine whether an initiated crack in an internally pressurized thermoplastics pipe will arrest or propagate. The standard covers test setup, pipe preparation, instrumentation and criteria for deriving critical pressure, critical hoop stress and critical temperature for rapid crack propagation (RCP). It applies to thermoplastics pipes used for gas or liquid supply (air may be present in liquid-filled tests).
Keywords: ISO 13478:2007, thermoplastics pipes, RCP, rapid crack propagation, full-scale test, FST, critical pressure, critical temperature.
Key topics and technical requirements
- Test principle: Initiate a longitudinal crack in a pipe maintained at a specified temperature and internal pressure; observe whether the crack arrests or propagates along the pipe length.
- Full-scale specimen: Typical overall pipe length is 14 m to 20 m (longer lengths or initiation-pipe inserts permitted for very RCP‑resistant materials).
- Controlled environment: Temperature‑controlled trough with uniformity to ±1.5 °C along the pipe; temperature monitoring at intervals (recommended every 3 m and around 3 o’clock/9 o’clock positions).
- Pressurizing fluid: Use service fluid or substitutes (air, nitrogen); test conditions reflect intended service conditions. Note: presence of entrained air influences RCP behaviour.
- Crack initiation: Machine an external slot (~500 mm constant depth, tapering to zero over ~250 mm) and drive a metal blade via pneumatic impact under cooled conditions (methylated spirits/ethanol cooled with solid CO2) to trigger the crack.
- Apparatus: Steel-pipe reservoir (minimum volume ≥ 3× test pipe), pressurisation system (±2% pressure control), crack-initiation equipment, wooden internal support with compressible foam to prevent distortion.
- Outcomes & measurements: Determine crack arrest vs propagation; from series of tests derive critical pressure (pc), critical hoop stress (σc) and critical temperature (Tc) (Annexes A and B).
Applications
- Qualification and performance assessment of polyethylene (PE) and other thermoplastic distribution pipelines for gas and water networks.
- Evaluating piping systems for resistance to rapid fracture under realistic, field‑like decompression conditions.
- Establishing safe operating limits, material selection, and design margins for buried or exposed pressure pipelines.
Who uses this standard
- Pipe manufacturers and material suppliers validating RCP resistance.
- Pipeline designers and civil/utility engineers assessing pipeline integrity and safety.
- Test laboratories performing full-scale RCP testing and certification.
- Regulators and standards bodies comparing test methods and approving products for service.
Related standards
ISO 13478:2007 provides a realistic, full‑scale methodology to quantify RCP resistance and derive critical service limits for thermoplastics pipe systems.