🔍 Key Concepts

• Coil-type water-tube, forced-circulation boiler construction (many small-diameter, tightly wound tubes) • How accessibility of the water-side surfaces affects both inspection and cleaning methods • Differences between mechanical cleaning (jets/brushes) vs chemical cleaning in very small, curved passages

💭 Think About

• Picture the inside of a coil-type boiler: are the water-side passages straight and open, or small, curved, and hard to reach? How would that affect visual inspection? • For narrow, tightly wound coils, which cleaning method can realistically reach all internal surfaces: something you insert physically, or something you can circulate through the coils? • If scale forms on the inside of many small coils, what method is commonly used in industry for such hard-to-reach internal surfaces?

✅ Before You Answer

• Verify whether coils in a forced-circulation auxiliary boiler are generally easy or difficult to inspect on the water side. • Consider whether mechanical cleaning tools (wire brushes, lances) can effectively reach through long, small, curved coils. • Consider if chemical cleaning with suitable acid solutions is typically used where internal surfaces cannot be reached mechanically.