🔍 Key Concepts

• thermal expansion of boiler drums during heating • which boiler parts are designed to be rigid supports versus flexible connections • how motion between parts is taken up in marine boiler construction

💭 Think About

• Which component in the choices could realistically flex or move slightly without cracking when the drum gets hotter and longer? • Which components are normally heavy, rigid, or anchored to the ship’s structure and therefore not intended to move with expansion? • Think about how the drum is connected to the rest of the boiler pressure parts: what forms the path for water/steam flow and can accommodate small movements?

✅ Before You Answer

• Eliminate any part that is primarily a structural support or anchorage to the hull. • Eliminate parts that are mainly for insulation or heat protection, not for movement. • Focus on the part that forms the pressure boundary connection between drums and can safely flex or accommodate small dimensional changes.