High-Pressure Water Descaling
The breaking and removal of thermal oxide layers from hot-formed semi-finished products using focused water jets at pressures exceeding 100 MPa. This avoids chemical acids during primary scale removal.
Water jet descaling is a purely mechanical process. You take a high-pressure water jet and blast the scale layer off the surface. It works without chemicals and is good for materials you don't want to treat with acid.
It's important to set the pressure and distance to the surface correctly. If the jet is too weak or you move too fast, scale remains. If you stay too long on one spot, you can attack the base material.
For welding, it's good because you get a clean, metallically bright surface. But after descaling, you have to be careful that the surface doesn't tarnish or get dirty again before you weld.