An assessment of the condition of the boiler tube is necessary to determine its fit for service, especially for an old boiler. Most of the time, the challenge is a limited record of the boiler inspection and design and commissioning data. This tube inspection and condition assessment needs to be conducted as part of the remnant life assessment. In the present work, inspections and remaining life assessments of tubes in the boiler in the petrochemical plant are reported. The tube inspection comprises a thickness survey, in situ metallography, and hardness measurement. The results show that all those data is correlated and can be used to estimate the boiler’s remaining life, which can also be used as a maintenance baseline for further operation. The present investigation is a field experience and might be used as a guideline for performing RLA for old boilers for fit-to-service or regulation needs.