Passivation and Common Corrosion Problems

It is a general rule that as boiler design pressure and heat flux increases, so the requirement for a progressively higher quality (higher purity) MU water also increases. 

As a result of these more exacting operational demands and the reduction in MU water dissolved impurities, basic waterside problems 

Problems of short-term and long-term overheating, which leads to fatigue and metal failure, also are associated with deposition on boiler surfaces and restricted BW flow—the particular mechanisms depend on the nature and quantity of the waterside deposits formed. 

As a consequence, when a boiler is taken offline (because of pitting corrosion, tube leaks, or some other problem), it is vitally important to understand the chain of cause and effect and to ensure that the correct remedy or work protocol is in place before putting the boiler back in service. 

In practice, the potential causes of boiler section corrosion are many and often commonplace. Initiators include oxygen, carbon dioxide, acid, caustic, copper plating, chelant, and even the water itself. In addition, mechanical problems may be an initiator of corrosion, which in turn may lead to boiler mechanical failure. 

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