What is the recommended pH range for boiler tubes and surfaces?

The recommended pH range for boiler tubes and surfaces is crucial for preventing corrosion and scaling, which can significantly impact the efficiency and lifespan of the equipment. A pH range of 7.8 to 8.5 is deemed optimal because it strikes a balance that minimizes the risk of acidic corrosion while also preventing alkaline conditions that could lead to scale formation.

At this pH range, the water is slightly alkaline, which helps form a protective layer on the metal surfaces within the boiler. This protective layer, often due to the presence of hydroxide ions, can effectively shield the metal from aggressive water chemistry and temperature changes that may otherwise lead to blistering or pitting.

In contrast, pH levels that are too low (like those in the options suggesting 5.5 to 6.5 or 6.7 to 7.7) may create acidic conditions that can accelerate corrosion processes. Similarly, pH levels that are too high (as suggested in the option of 8.6 to 9.5) could lead to increased risk of deposits and scaling, reducing heat transfer efficiency and harming the system over time.

Therefore, maintaining a pH of 7.8 to 8.5 is fundamental for the