1. In combination with a welding tractor for arc welding on vertical to horizontal curved surfaces of the type having a welding electrode, at least one welding powder vessel, and supply lines for powder application upon a weld zone and for covering the arc, an improved feed device for feeding granulated and powdery welding powders and additives comprising at least one welding powder vessel for pivoting about a horizontal axis on the welding tractor, means for holding the vessel such that the vessel is always held in a vertical position, independently of the angle of inclination of the welding tractor moving over the curved surfaces; a supply conduit pivotably mounted on each welding powder vessel, a powder applicator in communication with said supply conduit for receiving welding powder, and surrounding said powder applicator being rigidly arrangd on the welding tractor and surrounding the welding electrode for applying the powder upon the weld area.