ISO 13968:2008 defines a standardized test method for evaluating the ring flexibility of thermoplastics pipes with a circular cross-section.
The test is commonly used in plastics piping and ducting quality programs to determine the pipe deflection and the force at which physical damage (if any) occurs within a specified diametric deflection. If you need help determining whether this method applies to your pipe type or acceptance criteria, talk with our team.
ISO 13968:2008 — Plastics piping and ducting systems — Thermoplastics pipes — Determination of ring flexibility
ISO 13968 is a test method focused on how a thermoplastics pipe section behaves under controlled diametric deflection.
In practice, it is used to evaluate deformation tolerance and to document whether visible physical damage occurs during deflection up to the limit defined by the referring product specification or project requirement.
| Item | Details |
|---|---|
| Standard | ISO 13968:2008 (Edition 2) |
| Document type | International Standard (test method) |
| Published | October 2008 |
| Current status | Published; last reviewed and confirmed in 2023 |
| Technical committee | ISO/TC 138/SC 5 |
| ICS | 23.040.20 |
Quick Definition
What it is: A method for testing ring flexibility of a thermoplastics pipe (circular cross-section) by applying diametric deflection while monitoring force and checking for physical damage.
What you get: A force/deflection response and an observation of whether damage occurs within the specified deflection limit.
What it is not: A complete product specification or pass/fail requirement by itself; acceptance limits typically come from a referring pipe product standard or customer requirement.
What This Standard Covers
ISO 13968 covers ring flexibility testing for thermoplastics pipes with circular cross-sections.
The method is intended to determine the deflection and the force at which physical damage (if any) occurs within a specified diametric deflection. The exact deflection target and reporting expectations may be driven by the referencing specification or project document.
Why This Standard Matters in Testing
Ring flexibility is a practical performance indicator for plastic pipes that may experience installation loads, soil/compaction effects, handling deformation, or other service conditions that produce diametric deflection.
Using a standardized method helps labs and manufacturers compare results consistently across pipe types, sizes, and production lots, and it supports objective documentation for QA/QC and customer qualification.
Common Materials, Product Types, or Applications Covered
ISO 13968 is commonly applied to thermoplastics piping products where ring deformation behavior is relevant.
Common product context: Plastic pipes and ducting components with circular geometry used for fluid transport or ducting applications, where a customer, regulator, or product standard calls up ring flexibility verification.
Common Test or Verification Workflow
Most lab workflows for ISO 13968 follow a controlled compression/deflection approach on a pipe specimen.
- Prepare an appropriate pipe test piece (typically a cut section from production pipe) and document identification details required by the test plan.
- Condition and test at the specified temperature required by the purchase specification or referring standard.
- Apply diametric deflection in a controlled manner while measuring force and deflection.
- Observe and record any physical damage and capture the force/deflection response up to the specified deflection limit.
- Compile results and observations into a report aligned to the calling requirement.
Equipment Commonly Used for This Standard
ISO 13968 is typically performed using a compression-capable test frame with instrumentation suitable for capturing force and deflection during diametric loading of a pipe section.
Common equipment: A universal testing machine (or dedicated pipe ring test system) with compression platens or an appropriate pipe loading fixture, calibrated force measurement, and a deflection/displacement measurement channel.
Common accessories: Alignment aids/fixtures appropriate to the pipe diameter range, a data acquisition/control system to record force vs. deflection, and basic dimensional measurement tools for documenting pipe geometry called out in the test plan.
If you are selecting a system for a specific pipe diameter range or need guidance on fixture approach and data capture, you can request a detailed quote based on your specimen sizes and reporting requirements.
How to Read This Designation or Revision
ISO 13968:2008: “ISO” identifies the issuing body, “13968” is the standard number, and “2008” is the publication year for this edition.
Edition status: ISO 13968:2008 is Edition 2 and remains current (systematically reviewed and confirmed in 2023). An earlier edition, ISO 13968:1997, is withdrawn and should only be used when a legacy contract explicitly requires it.
Revision sensitivity: Test setup, conditioning, and reporting expectations can depend on the exact cited edition and any requirements in the referring product standard, so match your work instruction to the customer’s citation.
Related Standards, Methods, or Frameworks
Ring flexibility testing is often considered alongside other pipe mechanical property checks, especially when a product specification calls up multiple ring-property evaluations.
Commonly paired reference: ISO 9969 (ring stiffness of thermoplastics pipes) is frequently used in adjacent qualification programs where both stiffness and deformation tolerance are evaluated.
Talk with us about ISO 13968 testing setups
If you need help matching a test frame capacity, fixture style, and measurement package to your pipe size range and the exact ISO 13968 edition cited in your documentation, contact our team for practical guidance.