A plasma arc process and a combination plasma arc torch and nozzle assembly in which the arc plasma gas composition contains at least 50% oxygen. An oxygen containing reactive gas is passed through a gap between a first and second nozzle body of a nozzle assembly having a first and second arc constricting passageway adapted to constrict the arc plasma. The width of the gap is of a critical dimension to permit a tungsten electrode to be used without suffering from rapid electrode erosion.
