Which boiler water chemistry practice helps prevent corrosion and scaling in boiler tubes?

• A. Raising pH to extremely high levels is the primary method to prevent all corrosion.
• B. Allowing high chlorides to accumulate in water improves tube protection.
• C. Controlling pH/alkalinity to prevent corrosion, managing TDS to avoid carryover and scaling, and controlling chlorides/sulfates and iron to protect tubes.
• D. Ignoring TDS and relying on downstream chemical injection.

Answer: (C)

Preventing corrosion and scaling in boiler tubes relies on keeping boiler water chemistry within safe, recommended ranges and balancing several interdependent factors. Maintaining proper pH and alkalinity helps protect metal surfaces from acidic attack and supports a stable protective layer on the metal. Controlling total dissolved solids (TDS) prevents concentrated salts from precipitating as scale and reduces the risk of carryover that can deposit on heat transfer surfaces or in steam systems. Keeping chlorides, sulfates, and iron at low levels minimizes corrosive attack and reduces the formation of troublesome scales or deposits. When these elements are managed together, the tubes are protected from both corrosion and scaling, ensuring efficient heat transfer and longer equipment life. The other approaches—raising pH to extremes, allowing chlorides to accumulate, or ignoring TDS—risk causing more damage than they prevent.