Abstract: A conduit-cleaning assembly has a swivel coupling connected between a high-pressure hose and a conduit-cleaning nozzle. This coupling has an outer end tube connected to the hose, an intermediate outer tube threaded with the outer end tube, and an inner tube connected to the nozzle and forming with the outer tubes an axis-defining passage for liquid to flow into the nozzle from the hose. This inner tube is partially received in the outer tubes and has an inner-tube end whose outer edge engages an annular seal whose outer periphery is locked to the outer end tube. A bearing is provided between the inner tube and the intermediate tube to allow the parts to rotate relative to each other. The annular seal has a pair of opposite pressure-equalizing surfaces both exposed to the full pressure inside the swivel.