Overview
ISO 3127:1994 specifies a standardized impact test (round‑the‑clock method) to determine the resistance to external blows of thermoplastics pipes with circular cross‑section. The method is intended for isolated batches (and gives guidance for continuous production sampling) tested at 0 °C (with a note recommending −20 °C if lower temperatures are required). Results are expressed using the true impact rate (TIR) and classified as A, B or C relative to a 10% TIR criterion.
Key topics and technical requirements
- Scope and purpose: Assess external impact resistance of thermoplastic piping to support quality control, certification and specification.
- Apparatus: Falling‑weight testing machine with guide rails, a hemispherical striker (nose types d25 for 0.5 kg and 0.8 kg strikers; d90 for larger masses), release mechanism and a 120° V‑block support (≥200 mm long).
- Test pieces: Typical sample length is 200 mm ± 10 mm, ends square and undamaged. For pipes > 40 mm OD, equidistant lines are drawn around the circumference to define impact positions; pipes ≤ 40 mm OD receive a single blow.
- Procedure:
- Select striker mass and drop height as specified in the product standard or the ISO document.
- Condition test pieces at 0 °C ± 1 °C in air or liquid for specified periods (conditioning time depends on wall thickness and is given in the standard).
- Apply blows sequentially around the pipe (“round‑the‑clock”), re‑conditioning test pieces as required.
- A visible crack, split or shattering of the inner surface counts as a failure; indentation alone is not a failure.
- Evaluation:
- True impact rate (TIR) = total failures ÷ total blows (expressed as a percentage).
- Results are classified A (TIR ≤ 10%), B (indeterminate; further testing required), or C (TIR > 10%).
- Annexes provide sampling guidance for isolated batches and procedures for continuous production; Annex B gives PVC‑U specific information.
- Test report: Must include pipe ID, reference to ISO 3127, batch information, test temperature, striker mass and geometry, number of blows and failures, and final A/B/C result.
Applications and users
ISO 3127 is used by:
- Pipe manufacturers for product validation and quality control
- Independent testing laboratories and certification bodies evaluating impact resistance
- Standards writers and procurement/specification engineers requiring reproducible impact‑resistance data
- R&D teams developing thermoplastic pipe formulations and designs
Keywords: ISO 3127, thermoplastics pipes, resistance to external blows, round‑the‑clock method, impact testing, TIR, falling‑weight tester, pipe impact resistance.
Related standards
- Product‑specific pipe standards reference ISO 3127 for impact testing parameters (striker mass, drop height).
- ISO/TC 138 (Plastics pipes) is the relevant technical committee; ISO 3127:1994 replaces the 1980 edition.
Open preview (PDF)Thermoplastics pipes — Determination of resistance to external blows — Round-the-clock method
