Correct hydraulic parameters are required for safe long-term operation of coke batteries. Maintaining positive pressure in the ovens throughout coking preserves the lining of the coke oven, because air leakage into the chamber is prevented. The chronological development of concepts regarding coke-oven hydrodynamics is reviewed and, on that basis, low pressure in the coke ovens is shown to appear only in the case of lining defects or incorrect measurements. Therefore, the pressure in the gas lines of the coke battery should be considerably less than that currently employed, so as to decrease the leakage of raw coke-oven gas into the heating system. Such decrease in gas pressure in the coke ovens decreases the consumption of coke-oven gas in heating, without loss of coke quality. To maintain the lining of each coke battery, hot repair must be employed: for example, ceramic surfacing or welding; the application of special ceramic coatings; and stopping of cracks and seams by insertion of ceramic. In addition, by sealing cracks and seams with ceramic, the expansion of the lining may be slowed, with corresponding extension of battery life.