What action should be taken if a boiler tube cannot be removed but needs to be plugged?

When a boiler tube cannot be removed but needs to be plugged, the appropriate action is to puncture. Puncturing a tube allows for the removal of the weakened or damaged section while preventing the presence of steam or water from escaping, effectively sealing off the flow through that particular tube. This action is critical because it maintains the integrity and operational efficiency of the boiler system.

Using the puncture method enables the technician to efficiently deal with a problematic tube without the complexities and risks associated with sealing or welding, which could potentially lead to further complications or stresses in the boiler. As a result, puncturing simplifies the repair process while ensuring safety and reliability in the system's operation.