High Pressure Water Jetting (HPWJ)

The High Pressure Water Jetting process is the almost universal process, used in about 90% of all sewer cleaning processes for removing deposits within the scope of regular maintenance as well as for cleaning as a preparatory measure for sewer inspection or rehabilitation. It can usually be used when hardened deposits are present or for removal of flow obstacles, e.g. FOG, internally projecting laterals, artificial obstacles or roots or for achieving a very high degree of cleanliness on the inner pipe surface. In these cases additional use must be made of mechanical cleaning methods, which can partly also be driven by the high pressure water jetting machineries. In the High Pressure Water Jetting process, flushing water is pumped from a water tank by means of a high pressure pump through a hose with a cleaning nozzle at the end. The cleaning nozzle is equipped with holes, which beam the fast flowing water jets and direct them at the pipe walling. This causes a reaction force at the nozzle, which, in the first phase, force them and the hose in the sewer section, to move against the direction of the flow from the starting manhole to the target manhole.