Overview
EN ISO 11173:2017 specifies the staircase method for determining the resistance of circular thermoplastic pipes to external blows. The method, originally published as ISO 11173:1994 and adopted by CEN, is intended for isolated batches and is normally performed at 0 °C. The procedure produces an Hs0 value (drop height provoking 50% failure) useful for quality control, production monitoring and material selection.
Key Topics
- Test principle: Individual pipe test pieces are struck once by a falling striker (specified mass and nose geometry). Drop height is adjusted up or down in a staircase sequence depending on pass/fail results.
- Hs0 definition: Drop height for 50% failure, estimated from the sequence of impacts and calculated as the average of recorded drop heights in the main test.
- Conditioning: Test pieces are conditioned at 0 °C (liquid bath or air) for the period specified by wall-thickness criteria in the standard before impact.
- Apparatus:
- Falling-weight machine with guide rails and adjustable release (drop height up to at least 2 m; increments of 100 mm).
- Striker with hemispherical nose; typical nose types: d25 for 0.5 kg and 0.8 kg strikers, d90 for masses ≥1 kg.
- Rigid V-block support (or flat support for pipes with flat bottoms) aligned so impact point is near the vee axis.
- Sampling and test sequence:
- Preliminary test (up to 10 pieces) to find an initial failure height.
- Main test (at least 20 pieces); extend to 40 if fewer than required passes/failures are obtained.
- Each specimen is struck once and tested within 10 s of removal from the conditioning environment.
- Reporting: Include pipe identification, test temperature and medium, striker mass and nose diameter, number of specimens, Hs0 (rounded to 0.01 m), and any deviations or incidents.
Applications
- Quality control: Verify production batches meet impact-resistance requirements under standardised cold conditions.
- Material selection: Compare impact performance of different thermoplastics or wall constructions for external loading scenarios.
- Compliance & certification: Demonstrate conformity to product specifications or contractual requirements that reference EN ISO 11173.
Related Standards
- ISO 6603-1 (falling dart / impact testing) - referenced for statistical treatment and related impact-test methods.
- Product standards for specific pipe types often specify striker mass, acceptance levels and additional criteria; EN ISO 11173 provides the generic staircase procedure to be applied or adapted as required.
This content summarizes practical aspects of EN ISO 11173:2017 for engineers, test labs and quality managers working with thermoplastic piping systems. For full test details and normative tables, consult the complete standard.