Rapid crack propagation in plastic pipe: Predicting full-scale critical pressure from S4 test results/ RCP testing machine
Determination of resistance to rapid crack propagation (RCP) according to ISO 13477 (S4-test).
The small-scale steady-state (S4) test, evaluating rapid crack propagation (RCP) performance, is now an international standard for the specification of polyethylene fuel–gas distribution pipe. There is an emerging consensus, amongst users and material developers, that RCP must be guarded against and that the S4 test is useful for doing so. Argument continues, however, about the S4 critical pressure requirement, pcS4, which should be specified to qualify pipe for a given operating pressure. Due to the complexity of the phenomenon, the use of numerical simulation is inevitable. The numerical model has to account for the dynamic deformation and fracture of the structure, the gas dynamics of the pressurising medium and their interaction.
UnitedTest supply the testing program strictly follows the defined standards to control the testing temperature and pressure to reflect real-world conditions. The fluid used in the test reflects the characteristics of the expected application or serves as an equivalent substitute. The internal baffle and external cage play a crucial role in rapidly reducing pressure before slowing down crack propagation, ensuring the controllability of testing conditions. This carefully designed technique achieved steady-state rapid crack propagation (RCP) in short tube specimens, providing a more efficient alternative to full-scale testing. After testing, the inspected pipeline will be carefully examined to determine if cracks have occurred to prevent or propagate. A series of tests conducted at different pressures and constant temperatures enable precise determination of the critical pressure, critical ring stress, and critical temperature of RCP.
Testing machine used:
UnitedTest UT2039 series Plastic Pipe RCP test, Thermoplastics pipes for rapid crack propagation test machine.
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