The principle of ultrasonic inspection of thick-walled seamless steel pipes is that the ultrasonic probe can realize mutual conversion between electrical energy and sound energy. The physical characteristics of ultrasonic waves propagating in elastic media are the basis of the principle of ultrasonic inspection of steel pipes. The directionally emitted ultrasonic beam generates a reflected wave when it encounters a defect during propagation in the steel pipe. After the defect reflected wave is picked up by the ultrasonic probe, the defect echo signal is obtained through flaw detector processing, and the defect equivalent is given.

Detection method: Use the shear wave reflection method to inspect while the probe and the steel pipe are moving relative to each other. During automatic or manual inspection, it should be ensured that the sound beam scans the entire surface of the pipe.
Defects in the longitudinal inner and outer walls of steel pipes should be inspected separately. When inspecting longitudinal defects, the sound beam propagates in the circumferential direction of the pipe wall; when inspecting transverse defects, the sound beam propagates in the pipe wall along the axis of the pipe. When detecting longitudinal and transverse defects, the sound beam should be scanned in two opposite directions in the steel pipe.

The flaw detection equipment includes pulse reflection multi-channel or single-channel ultrasonic flaw detectors, whose performance must comply with the regulations of JB/T 10061, as well as probes, detection devices, transmission devices, and sorting devices.