Abstract : This paper analyzes the installation, commissioning, and usage of the hydraulic AGC servo system in the 3000mm medium plate rolling mill of Wuhan Iron and Steel Group (WISCO), illustrating some basic issues in pollution control of the hydraulic AGC servo system. The actual operation of the 3000mm rolling mill at WISCO proves the success of the pollution control of the hydraulic AGC servo system. Keywords : Hydraulic AGC; Pollution control; Electro-hydraulic servo system 1 Introduction Faced with fierce market competition and development needs, the development direction of steel rolling technology is to improve product quality, increase yield, develop high-value-added and high-performance steel plates, and reduce costs to meet users' increasingly higher requirements for the quality and specifications of steel plates. The hydraulic automatic thickness control device (HAGC) has technical advantages such as fast dynamic response, high control accuracy, and good acceleration performance. During the rolling process, it can control the roll gap in real time, eliminate thickness deviations caused by various disturbance factors, and maintain a stable plate thickness at the mill exit. Nearly 30 years of practical application have proven that the hydraulic AGC device is an important technical equipment for solving longitudinal thickness differences in finished strips, improving yield, enhancing automation, increasing productivity, and stabilizing and optimizing the rolling process. To improve product quality and market competitiveness, and to develop high-value-added, high-performance steel plates, Wuhan Iron and Steel (WISCO) upgraded and updated its old 2800mm rolling mill in December 1998. Utilizing the original foundation, a new 3000mm rolling mill with high rigidity and a new high-precision hydraulic AGC device was built. The upgrade project was completed and put into operation in March 1999. 2. Pollution Control Scheme The WISCO 3000mm rolling mill's hydraulic AGC servo system operates at a pressure of 25MPa with a maximum flow rate of approximately 1400L/min. It features high pressure, high flow rate, and high power. The precision hydraulic components of the hydraulic AGC servo system, such as the electro-hydraulic servo valves, pressing servo hydraulic cylinders, and high-pressure column pumps, are sensitive to oil contamination. Deterioration in oil cleanliness directly leads to decreased system performance, shortened component lifespan, and may cause sudden failures, affecting system operation. Therefore, to ensure the continuous, safe, reliable, and stable operation of the hydraulic AGC servo system, the cleanliness of the working oil must reach NAS5-6 level. Pollution control can be summarized in two main points: First, before the hydraulic AGC system is put into operation, any residual contaminants in the system must be removed to meet the requirements for normal system operation. Second, after the hydraulic AGC system is in operation, the generation and intrusion of contaminants must be controlled to achieve a dynamic balance of contaminants in the system's working oil. This balance should be maintained below the contamination level that the components can tolerate, ensuring the system operates normally and reliably. [b][align=center]For more details, please click: Pollution Control of the Hydraulic Automatic Thickness Control Servo System for the Wuhan Iron and Steel 3000mm Rolling Mill[/align][/b]