What is used to maintain a record of defective boiler tubes and newly renewed tubes?

The correct answer is the boiler tube renewal sheet. This document specifically helps in tracking both defective boiler tubes that need replacement and newly installed tubes following maintenance. It serves as a comprehensive inventory of changes made to the tubes and is crucial for ensuring that all boiler tubes are up to the required standards for safety and efficiency.

Using a boiler tube renewal sheet allows for organized record-keeping, enabling maintenance personnel to easily reference the status of each tube and schedule future inspections or renewals accordingly. This tracking mechanism is essential not only for maintaining operational efficiency but also for compliance with safety regulations.

In contrast, the other options do not serve the same specific purpose. A boiler tube inspection log would focus more on inspections and findings rather than specifically documenting renewals. A maintenance activity report generally covers broader maintenance activities and may not concentrate solely on boiler tubes. A repair and renewal log might include a variety of repairs across different systems, lacking the specificity needed for detailed boiler tube records.