🔍 Key Concepts

• Thermal expansion of pressure parts in a boiler • Which components are designed to move vs. which must stay rigidly aligned • How the boiler drum is supported on its foundation or structure

💭 Think About

• Which part of the boiler support arrangement would most likely be designed to slide as the drum grows longer with heat? • Which listed components must maintain a tight, gas‑tight, or pressure‑tight seal and therefore are poor candidates for movement? • Think about what happens to the drum length when going from cold iron to full operating temperature – where can that movement be safely absorbed?

✅ Before You Answer

• Identify which option is associated with structural support of the boiler assembly, not sealing or lining. • Eliminate options that must remain fixed and tight to preserve pressure or combustion gas tightness (tube-to-sheet, casing, refractory). • Ask yourself: which component’s very purpose is to allow movement due to thermal expansion rather than resist it?