The test under practical conditions simulates the loads that are imposed by the pressurized water jets in combination with the mechanical loads caused by the flushing head and the hose during high-pressure cleaning. Testing is done on a straight track of at least 15 m in length, using a standard radial nozzle with 8 ceramic nozzle inserts of 2.6 mm opening width and a jet angle of 30°. A total of 60 cleaning cycles are tested with a driving velocity of 0.1 m/s and a flushing jet power density of 330 W/mm².

Upon completion of testing under practical conditions, the pipe surface under the test location is to be visually inspected and compared to its initial condition. Here too, the test results have to be evaluated according to Appendix A of the DIN 19523. The pipes have passed the test when they meet the requirements of the respective standard even after being exposed to the above-mentioned test loads [DIN19523].

In addition to the examination of the behaviour of pipes, pipe joints, linings, coatings, etc. in high pressure cleaning, it is also required to test, for example, inlet or lateral connections. Such a test method has been developed for the registered professional association for concrete and reinforced concrete pipes (FBS) [S&P1996].

The test is carried out on sewage pipes size DN 300 (12''), to which lateral connections are installed by the manufacturer or distributor at the spring line (or rather between the spring line and the crown). A standard cleaning vehicle with a maximum water pressure of 210 bar is used in the flushing tests. The cleaning nozzle which is used has 10 nozzle apertures with individual diameters of 2 mm and a jet angle of 45°. Water is supplied via a high-pressure hose with a length of 120 m and a 25 mm diameter.

The investigation program includes both stationary (cleaning nozzle pausing at one particular point due to a work interruption) and dynamic tests (long-term stress imposed by frequent cleaning).

In the stationary test, the cleaning nozzle is kept fixed in place, lying on the pipe invert at the height of the connection inlet. Starting from an initial pressure of 75 bar, the flushing pressure is increased in pressure stages of 25 bar up to a maximum of 150 bar. In each stage, the pressure is maintained for one minute. Afterwards, the connection inlet system is visually inspected.

To simulate long-term stresses, the cleaning nozzle is pulled through the respective pipe for a total of 50 times at a constant flushing pressure of 150 bar (measured at the high-pressure pump) and a velocity of about 4 m/min. Afterwards, the inlet of the service pipe is visually inspected and quantitatively checked through leak-tightness testing.

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