Pay attention to preventing corrosion in the shut-down boiler

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If appropriate protective measures are not taken during the shutdown period of the boiler, the metal surfaces of the boiler itself and the entire steam-water system will be corroded by dissolved oxygen, and the rate of corrosion is much faster than during operation. It has been found that boilers with severe corrosion are mostly due to improper shutdown protection, and if these corrosion products are not removed, they will accelerate electrochemical corrosion once the boiler is restarted. Therefore, shutdown corrosion not only shortens the service life of the boiler but also creates potential hazards during operation. After the boiler is shut down, a large amount of air from the outside environment enters the boiler’s steam and water system. Especially when the boiler is cooled and drained without being dried, a layer of water film forms on the metal surfaces; oxygen in the air can easily dissolve in this water film and reach saturation. When oxygen reacts with iron, it is quickly replenished by more oxygen from the air, which makes oxygen corrosion of the metal very likely to occur. Corrosion becomes more severe if the furnace water remaining on the metal surface contains Cl- or SO42-.