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

The correct answer is the boiler tube renewal sheet, which is specifically designed to document details about defective boiler tubes as well as the tubes that have been replaced or renewed. This sheet serves as an essential record for maintenance personnel, ensuring that there is a clear history of which tubes need attention and when they have been replaced. This information is crucial for maintaining the efficiency and safety of the boiler system, as it provides insights into the performance and longevity of each tube, helping to identify patterns of failure and allowing for better planning of maintenance activities.

In contrast, while a boiler tube inspection report could document findings from inspections, it does not specifically track the renewal of tubes. The boiler maintenance log typically records all maintenance activities but may not focus on the specifics of tube defects and renewals. The boiler condition matrix is more likely concerned with the overall operational status of the boiler rather than detailed records of tube transactions. Therefore, the renewal sheet is the most appropriate tool for this particular record-keeping purpose.