Engineering · Steam — Water Treatment
Scale formation on the water side of boiler tubes is harmful mainly because it:
- AIncreases heat transfer and overheats the water
- BInsulates the tubes, causing overheating and possible failure✓ Correct
- CLowers the boiler pressure
- DImproves circulation
Explanation
Scale (from hardness salts) is a poor conductor. It insulates the metal from the cooling water, letting tube metal overheat, weaken, and rupture. Feedwater treatment controls scale-forming salts.
Authority: Steam Plants (USCG engineering topic)
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