Why are hard scale deposits on the inside of...

Question 1 / 270705eccefa0bacbc34ba4d46fbc

Question 1 of 270705eccefa0bacbc34ba4d46fbc

Why are hard scale deposits on the inside of boiler tubes most objectionable?

Question 1 of 27070

Why are hard scale deposits on the inside of boiler tubes most objectionable?

🔍 Key Concepts

• Boiler tube heat transfer – how heat moves from the flame, through the tube metal, into the water/steam • Effect of scale (insulating layer) on the rate of heat transfer and tube metal temperature • Difference between flow restriction problems and overheating/rupture problems

💭 Think About

• Ask yourself: what is the main job of a boiler tube, and how would an insulating layer on the inside affect that job? • Which consequence of scale will most quickly lead to serious tube damage or failure under high pressure and temperature? • Is scale more like an insulator or a corrosive chemical, and what does that imply for tube metal temperature?

✅ Before You Answer

• Verify which choice directly involves heat transfer and tube wall temperature, not just water flow. • Identify which options describe long-term chemical effects versus immediate physical/thermal effects. • Check which outcome would most likely cause tube failure or rupture, which is what exam questions usually mean by "most objectionable".

Question 1 of 27070

Why are hard scale deposits on the inside of boiler tubes most objectionable?

Flow of water within the tube is restricted.

Poor heat transfer due to hard scale deposits overheats tubes.

The metal of the tube interior is eaten away by scale.

Hydroxyl ions liberated by the scaling process form acid in the boiler water.

Question 1 / 270705eccefa0bacbc34ba4d46fbc

Question 1 of 270705eccefa0bacbc34ba4d46fbc

Why are hard scale deposits on the inside of boiler tubes most objectionable?

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Question 1 of 27070

Why are hard scale deposits on the inside of boiler tubes most objectionable?