EN 743 specified test procedures for measuring the longitudinal reversion of thermoplastic pipes after exposure to heat. It defined sampling, heating, and measurement steps to help assess thermal stability, control quality, and ensure compliance. The standard has been replaced by EN ISO 2505.
EN 743: Determining longitudinal reversion in pipes
EN 743 specified a test method for determining the longitudinal reversion of thermoplastic pipes. This standard was primarily used to assess the dimensional stability of plastic pipes when exposed to elevated temperatures, focusing on possible changes in length after heat treatment. The test helped manufacturers and quality controllers verify product performance, ensure compliance with requirements, and maintain consistency in pipe production. The standard has been superseeded by EN ISO 2505, which continues to provide guidance on evaluating the reversion characteristics in thermoplastics pipes and ducting systems.
Importance of the standard in manufacturing
The reversion test outlined in EN 743 aimed to ensure that thermoplastic pipes retain their shape and dimensions during and after installation, even when exposed to heat. Excessive reversion could affect the integrity or usability of pipes, so the standard provided a uniform method for assessment. By following EN 743, manufacturers could minimize risk of failure associated with thermal instability and provide reliable piping products for both pressurized and non-pressurized applications.
Document structure and supersession
EN 743 included instructions for sample preparation, test temperature, immersion times, and methods for measuring longitudinal reversion. The procedure’s structure has been maintained in the newer EN ISO 2505, but updated with additional guidance and harmonization with international testing approaches.
Takeaway
EN 743 played a crucial role in qualifying the heat resistance and shape stability of thermoplastics pipes. Although now replaced by EN ISO 2505, it remains a reference point for legacy systems and understanding test evolution in the plastics pipe industry.
Test preparation and sample selection
Begin by selecting representative samples of the thermoplastic pipe to be tested, ensuring the number and dimensions conform to the requirements given by the standard. Visually inspect each section to ensure they are free from surface defects that might affect results. Prepare ends by cutting them cleanly and squarely, and ensure all samples are at ambient laboratory temperature prior to starting the procedure.
Heating and immersion
Immerse the prepared pipe samples in a water bath or circulating air oven maintained at the specified test temperature. The immersion and heating times depend on the pipe wall thickness and standard guidelines.
Cooling and measurement procedures
After the required exposure, remove the samples and allow them to cool to room temperature. Once cooled, measure the final lengths between marked points on each sample, noting any changes relative to the original measurements. This value represents the longitudinal reversion, typically expressed as a percentage shrinkage or extension from the initial length.
Calculating and recording results
Document all measured data, including original and final lengths, test temperature, and time. Calculate the percentage of longitudinal reversion for each sample following the specified formula from the standard. Compare recorded results to specified limits for the application to determine compliance and note any deviations for further investigation.
Reporting and quality control actions
The final step involves preparing a comprehensive test report, summarizing methods, conditions, and findings. Results should be archived and compared against production and quality control data for trend analysis or batch release decisions. If non-conformance is identified, undertake a root cause analysis and review corrective actions in the manufacturing process as necessary.
Summary
The EN 743 test provided a systematic approach to evaluating pipe stability during heat exposure, now formalized in EN ISO 2505. Adhering to the step-by-step process ensures consistent, traceable, and reliable assessments of thermoplastics pipe quality.
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