Theory and practice of steel surface protection in boilers

摘要

Protective magnetite steel surface layers developing in steam generators may be subject to aggressive attacks. However, even if general guidelines for the bulk water are met with respect to the water purity (acid conductivity) and conditioningchemicals, damage can occur. The reason may be the disregarding of interaction among material, design and chemistry. Different boiler water treatments are discussed in detail. The influence of pressure and pH on the stability of the protective layer isdescribed. Experience on how solid alkaline conditioning combined with inadequate design can result in severe corrosion and boiler tube failures is outlined. It is also being described how simple modifications of the boiler design can resolve solidalkaline corrosion.