A descaling device for slabs or strips in hot rolling mills includes nozzles fed by a pressurized water piston pump for directing water jets against the slab or strip for removing scale adhering to the surface of the slab or strip. At least one additional pressurized water piston pump is provided, wherein the piston pumps are connected in parallel and the pumps can be switched on and off separately. A second row of nozzles may be arranged in front of the nozzles at a distance which ensures that the water jets do not influence each other. The water pressure of the water supplied to the second row of nozzles is preferably lower than the water pressure supplied to the first row of nozzles. 13
