The API standard stipulates that the inner and outer surfaces of the imported and imported petroleum casings must not be folded, separated, cracked or scratched, and these defects should be completely removed. Petroleum casing must be fully covered for automatic wall thickness detection. Currently, there is an indirect measurement method of wall thickness based on the principle of magnetic flux leakage. It is not a method of directly measuring the wall thickness, but a method of indirectly measuring the wall thickness by measuring the magnetic field change information caused by the wall thickness change.

Therefore, the strength of the magnetic field has a great influence on the accuracy and resolution of wall thickness detection, and is not suitable for online automatic detection. The design and selection of the probe is critical to the thickness of the oil casing. The sound beam emitted by the round crystal piece of the general probe has a certain diameter and expands with increasing distance. Selecting the acoustic beam to focus locally through the acoustic lens to increase energy.