What is the purpose of beading some tube ends in a water tube boiler?

The purpose of beading some tube ends in a water tube boiler is primarily to keep them secured and prevent air pockets. Beading involves forming a bead or raised edge at the end of the tubes, which helps ensure a tight and secure fit when the tube is inserted into the headers or drum. This design feature is essential because it creates a mechanical seal that minimizes leaks and air pockets that can disrupt the flow of water and steam within the system.

A well-sealed connection ensures that the boiler operates efficiently and safely, maintaining the intended pressure and temperature without the risk of air entrainment, which can lead to cavitation or other operational issues. Effective sealing through beading also extends the lifespan of the boiler components by reducing wear and tear caused by improper fits or excessive movement.

While other choices relate to aspects of boiler performance, they do not directly address the specific role that beading plays in securing the tube ends and promoting effective system function.