EN 12 293 specifies the method for testing ring flexibility of thermoplastic pipes used in non-pressure underground drainage and sewerage. It defines sample preparation, test procedure, required deformation, and criteria for visual defects to ensure pipes maintain structural integrity during installation and use.
Definition and scope
EN 12 293 is a European standard that specifies the method for determining the ring flexibility of thermoplastic pipes. This standard applies to thermoplastic pipes intended for non-pressure underground drainage and sewerage. The test evaluates a pipe’s ability to undergo significant deformation without showing signs of breaking or cracking, which is essential for pipes that are expected to endure earth loads and installation stresses.
Procedure outline
The EN 12 293 test involves compressing a pipe sample between parallel plates until it reaches a predefined deformation, typically 30% of the pipe’s outer diameter. Throughout the test, the operator must observe for visible cracks or breaks, as these would indicate failure of the sample against the standard. The test method is applicable to pipes with circular cross-sections made of thermoplastic materials, ensuring the product can withstand deformation encountered during installation and use in underground environments.
Critical test parameters
The standard specifies both the test speed and environmental condition, such as temperature and humidity, at which testing should be conducted. Parameters like pipe diameter, wall thickness, and material composition must be recorded. The results of the test, including whether any visible defects develop, determine the product’s compliance with the requirements of EN 12 293.
Takeaway
EN 12 293 plays a central role in assuring the mechanical reliability of thermoplastic pipes used for drainage and sewerage systems. Compliance is important for manufacturers, specifiers, and installers in order to meet European quality and safety requirements.
Selecting and preparing pipe samples
Prepare pipe samples as specified in EN 12 293. Use pipes of the designated diameter and wall thickness, ensure samples are free from surface defects, and cut them to the correct length, typically not less than 300 mm or six times the nominal diameter, whichever is greater. Condition samples to the specified test environment before starting the test.
Setting up the test apparatus
Set up a compression testing machine with parallel plates, suitable for applying the required deformation. Check that the machine meets EN 12 293 accuracy requirements for force and deformation measurements.
Performing the compression test
Compress the pipe sample at a controlled speed, as defined by EN 12 293, until a deformation equal to 30% of the original outer diameter is reached. Observe the sample for any signs of visible cracking or breaking during and after the compression. Record any changes along with the test forces applied at maximum deformation.
Evaluating and documenting results
Carefully inspect the deformed section for failure criteria as stated in EN 12 293 (e.g., visible cracks or breaks). Document the test setup, specimen dimensions, material type, environmental conditions, test speed, deformation, and observations. Determine compliance with EN 12 293 based on presence or absence of visible damage under specified deformation.
Reporting according to EN 12 293
Prepare a report that includes all information required by EN 12 293, such as the identification of the pipe, test conditions, procedures used, observed results, and conclusion on compliance. Attach original data sheets and photographs if necessary for further traceability and demonstration of process transparency.
Summary
EN 12 293 provides a clear methodology for testing ring flexibility in thermoplastic pipes. By following the outlined steps, manufacturers and test laboratories can confirm product suitability for use in buried sewer and drainage systems, ensuring compliance with European structural performance requirements.
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