Final answer:
The ends of fire tubes are flared and beaded to aid in the flow of flue gases and accommodate expansion and contraction.
Step-by-step explanation:
The ends of fire tubes in boilers are often flared and beaded for two main reasons:
- To aid in the flow of flue gases: The flared and beaded ends create a smoother transition for the gases, reducing turbulence and improving the efficiency of heat transfer.
- For expansion and contraction: Flaring and beading the ends allows the tubes to expand and contract without causing damage or leaks. It provides a mechanical lock between the tubes and the tube sheets, ensuring a secure connection.