Pressure fatigue test on thermoplastic or elastomer pipes
Fatigue Test : Pulsating Pressure
The test that is typically used to test pipelines for pressure fatigue is pressure pulsation.
The main parameters of the test are:
- Pressure level
- Pressure waveform and frequency (trapezoid or sine)
- Fluid and ambient temperature
- Fluid flow rate
- Number of cycles under pressure
- Type of fluid
The parameters are set according to the type of application of the pipeline.
Another factor that affects the test result is the assembly lay-out which should be the same as the operating one and in any case respect the minimum bending radii envisaged in the project.
Fig.1 Example of trapezoidal waveform required by automotive test specifications
Fig. 2 Esempio di montaggio secondo lay out vettura
PVT Test
In automotive applications, the presence of vibration at the same time as pressure and temperature is often required (PVT test).
This test is typically used in pipelines where quick connector type end fittings are fitted.
Fig. 4 PVT test
What defects can be observed during a pulse pressure test?
Defects can translate into oozing-leakage-leaks and bursts.
Normally the pressure level at which the test is performed is higher than the operating one
The level of hardening is dictated by the number of cycles to be used to simulate the “life” of the component. During the product qualification phase, a minimum number of cycles may be required and once this is reached, bring at least one sample to breakage.
In any case, pulse pressure tests have a minimum duration of 100,000 cycles and therefore the duration of a test is generally several days.
For more information visit our site on laboratory tests where you will find the vibration tests you are looking for!
A special thank you goes to Noris Vivarelli, a great expert in the vibration and fluid-dynamic sector, as well as Plastlab Laboratory Manager, who raises our awareness on this issue so as to provide us with new content for these #laboratory pills!
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