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In light of the background on pitting corrosion in the heat transfer tubes of steam generators mentioned earlier, the following are the key factors that accelerate this type of corrosion: Water chemistry impurities – An increase in the levels of chlorides and sulfates in the feed water on the secondary side, or salts introduced due to leaks in the condenser, can lead to the concentration of these substances in certain areas, creating an acidic environment. This significantly speeds up the corrosion rate of carbon steel support plates, resulting in the formation of large amounts of corrosion products that press against the tube walls and cause pitting. Dissolved oxygen and metal ion factors: When there is an adequate level of dissolved oxygen in water, along with the presence of copper ions or copper oxides, this provides an additional oxidative driving force for the corrosion of carbon steel, further accelerating the formation of corrosion products and shortening the time required for pits to form. Structural and temperature factors: The gap overheat in the heat transfer tube section is higher, and local temperature increases significantly accelerate the corrosion reaction rate, causing the formation of indentations to proceed much more rapidly than in the cold end area. Water chemistry factors: The water chemistry model that employs full vaporization treatment (AVT) lacks buffering substances such as phosphates, which are needed to maintain a high pH level in the gaps; as a result, local acidic corrosion cannot be suppressed, thereby significantly increasing the likelihood of pit formation. Gap size factor: When the annular gap between the heat transfer tube and the carbon steel support plate is within the appropriate range, it is easier to create a locally concentrated environment that leads to blockages, accelerating the accumulation of corrosion products and facilitating the rapid formation of indentations.