Installations and devices for water jet cutting/removal, in particular for water abrasive and/or water abrasive suspension cutting/removal (water jet cutting/removal machines); machines for high-pressure processing of surfaces with water and water abrasive suspensions, in particular machines for processing interiors of pipes or conduits with high-pressure water jets and/or high-pressure water abrasive suspensions; valves (machine parts); nozzles as machine parts, in particular swirl nozzles, cutting nozzles, removal nozzles, discharge nozzles for discharging liquids and liquids with added abrasive and/or suspensions, in particular for water and/or water-abrasive suspensions under high pressure.