The descaling process is crucial in steel industry to obtain higher quality products. Descaling nozzles are used for an efficient scale removal in hot rolling. The best method is the hydro-mechanical descaling process using high pressure water jets formed by special descaling nozzles. Working pressure range is from 50 to 400 bar (725 to 5.800 psi ), for GW type from 30 to 200 bar ( 435 to 2.900 psi). The impact of the water jet on the steel hot surface produces an impact force that, combined with the thermal action due to the temperature difference between jets and slabs, generates the descaling effect. The jet quality of the nozzle has a great effect upon the steel surface descaling in hot-rolling and is crucial for the quality of the final product.