This paper discuses assessment and repair methodology for the Boiler tubes. The subject boiler experienced defective tubes that impacted its operational efficiency. Defective tube presence had a significant effect on Boiler reliability and would lead to operational failure if it was not appropriately maintained. Interrelated chronic issues required a systematic analysis to identify the optimum repair methodology. The impacted Boiler was evaluated through life assessment procedure and recommended to be re-tubed. A specific repair procedure was proposed to tackle this failure. Feasibility and cost-effectiveness of the Boiler settlement, age, and structural durability was considered while repairing this equipment. As a result, both reliability and maintainability have been enhanced following re-tubing project completion addressing all defective tubes and returning equipment back to operation.