How to adjust environmental controls to prevent corrosion

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If all factors in the environment that cause corrosion could be eliminated, corrosion would cease or slow down. However, most environmental conditions cannot be controlled; for instance, it is impossible to remove moisture from the atmosphere and soil, or oxygen from seawater. The chemical production process cannot be altered arbitrarily either. However, some local conditions can be adjusted; for example, deoxygenating the water entering the boiler by adding deoxidizing agents such as sodium sulfite and hydrazine can protect the boiler tubes from corrosion. The air entering a sealed warehouse has its moisture removed first, preventing the metal components stored there from rusting. If changing the environment does not affect the product or the manufacturing process, this method can also be applied to some production processes. To prevent cooling water from causing scaling and perforation in heat exchangers and other equipment, alkalis or acids are often added to the water to adjust the pH value to an optimal range (usually close to neutral). In refining processes, alkalis or ammonia are also often added to keep the production fluid neutral to alkaline. If the temperature is too high, it can be reduced by cooling the vessel walls, or insulation can be achieved by lining the inner walls of the equipment with refractory bricks. If permitted, milder media can be used in the process as alternatives to highly corrosive media.