Operating experience with flushing shields (cont.)

• Due to its design, the flushing shield cannot be used to clean the air space of the pipe. Thus, this method is not appropriate for cleaning prior to inspections or rehabilitations.

• Solidified deposits are not mobilized.

• The flushing shield can get jammed or stuck on lateral pipe connections. In this case it has to be manually repositioned.

• By backing up the sewage behind the flushing shield, the remaining flow cross section is considerably limited. Sudden precipitation events or an increased sewage flow can result in uncontrollable upstream pressures.