Hot-Gas Descaling
A thermochemical process for removing scale layers on steel surfaces using reactive gases at elevated temperatures prior to subsequent coating steps.
Hot gas descaling is basically a controlled burning off of the scale. You heat the part and then run a reactive gas over it that loosens and removes the scale layer. Grease and oil burn off at the same time. It's important to keep an eye on the temperature. If it gets too hot, you ruin the structure; if it's too cold, nothing happens and the scale stays on. For welding, this is crucial: without a clean, scale-free surface, you won't get a proper weld and later problems with coating adhesion. In practice: gas on, set temperature, and watch the time. When the surface has flaked off evenly, let the part cool slowly and you can continue working.