🔍 Key Concepts

• Heat transfer and metal deformation in fire-tube (Scotch) auxiliary boilers • Effects of waterside vs. fireside problems (deposits, alkalinity, firing rate) • Relationship between tube/crown sheet overheating and distortion

💭 Think About

• Which option directly causes the metal of the furnace or crown sheet to become excessively hot, softening it so pressure can deform it? • Which options mainly affect water chemistry or normal operation, and would cause other issues (like foaming or corrosion) before actually distorting the furnace? • Think about how an insulating layer (on which side?) would change heat transfer and metal temperature.

✅ Before You Answer

• Identify which choice most clearly leads to localized overheating of furnace metal rather than just general poor operation • Consider whether water level variations alone are likely to physically distort thick furnace plates under normal operation • Distinguish between issues that primarily cause chemical/water quality problems and those that cause mechanical deformation from heat and pressure