Abstract: To address the issue that the riding ring surface of the steam tube rotary dryer in PTA units is prone to wear, scratches, and pitting during long-term operation, an on-line turning of the riding ring method is proposed for repair. Practical application demonstrates that this method enables on-site inspection, turning, and grinding of the riding ring surface without dismantling, while effectively controlling its surface roughness and dimensional accuracy. This process ensures controllable repair quality, saves time and labor, significantly reduces downtime for resuming production, and guarantees the long-cycle stable operation of the unit.