Laser ultrasonic system for metal pipe wall thickness measurement: Differential signal processing and geometric compensation calculation model

Metal pipes are extensively utilized in various industries. However, uneven wall thickness resulting from aging, corrosion, and other factors can pose safety hazards. While traditional inspection methods have limitations, laser ultrasonic technology provides non-contact, long-distance detection, making it suitable for online inspection in challenging environments. In this study, laser ultrasonic technology is employed to detect the wall thickness of metal pipes, overcoming challenges such as same-side detection and signal processing. A signal processing method based on the differential algorithm successfully extracted a clear and stable longitudinal wave signal while effectively suppressing noise interference. Additionally, a new wall thickness calculation model considering the pipe's geometry is developed. Experimental validation demonstrated that the calculation results of the model are in good agreement with the actual measured values, with a relative error of 2.19%. These results confirm the high accuracy and reliability of the laser ultrasonic method in the wall thickness inspection of metal pipes and demonstrate its potential in this field.