Which of the following would not prevent boiler tube corrosion?

Slightly acidic boiler water would not prevent boiler tube corrosion because acid contributes to the deterioration of metal surfaces. Corrosion is an electrochemical process that is accelerated in acidic environments, as acids can increase the rate at which metals like steel or iron oxidize. Therefore, having even slightly acidic conditions in the boiler water creates an environment that can lead to pitting and thinning of boiler tubes, ultimately compromising their structural integrity.

Proper chemical treatment and phosphates are used to maintain the correct pH level and form protective layers on the metal surfaces in the boiler, which helps to prevent corrosion. An open feedwater heater can also aid in the prevention of corrosion by allowing for better temperature control and deaeration, which helps reduce oxygen content in the water, another contributor to corrosion.