The maintenance and inspection of large vertical or horizontal tubes in an autonomous manner is still an unsolved issue. Existing techniques can traverse various types of surfaces but cannot measure inner cracks in a long tube. However, most of these techniques are restricted by accuracy level, type of construction material and cost efficiency. This research is mainly focused on the studies of various types of design investigations related to the climbing robots for the inspections, and design and development of a new robot to solve the existing problem in measuring various pipes diameter in petroleum industries. Based on the existing prototypes, a new type of adhesion, locomotion, sensor mechanisms and a modernized design was accomplished. The importance of this work is to prevent hazardous failures, which probably can be determined through the on-site analyses of the tubes. At this point, it is a laborious, time-consuming and dangerous process, which is performed by the human being. Finally, a climbing robot based on duct fan is designed and developed as a prototype. The thrust force, provided by the fan, ensures that the robot is not falling while the DC motors generate the motion. The ultrasonic sensor is chosen for the defect detection. It generates a reference signal of a proper tube and compares it to the signals received from the defected tubes. The preliminary design and development of the robot are done in SolidWorks software together with the available components in the market.