API standards stipulate that the internal and external surfaces of import and export oil casing shall not be folded, separated, cracked, or scarred. These defects should be completely removed, and the removal depth should not be less than 12.5% of the nominal wall thickness. Petroleum casing must undergo full coverage automatic wall thickness detection. Currently, there is an indirect measurement method of wall thickness based on the magnetic flux leakage principle. It is not a method of directly measuring wall thickness, but a method of indirectly measuring wall thickness by measuring the magnetic field change information caused by changes in wall thickness.

Therefore, the magnetic field strength has a great impact on the accuracy and resolution of wall thickness detection and is not suitable for online automatic detection. Magnetic ultrasound does not require a coupling agent, but it is difficult to excite ultrasound in pipes with uneven surfaces. Industrial ultrasonic phased array probes have high manufacturing costs and complex systems. At present, this kind of equipment rarely appears in our country.

Based on the principle of ultrasonic measurement of petroleum casing wall thickness, petroleum casing manufacturers analyzed focusing probes suitable for automatic detection of petroleum casing, and selected appropriate focal length and chip size probes to form a full-coverage automatic wall thickness detection system. There are obvious improvements. The design and selection of the probe are crucial to the thickness of the oil casing. Generally, the acoustic beam emitted by the circular crystal piece of the probe has a certain diameter and expands as the distance increases. The acoustic beam is selected to focus locally through the acoustic lens. to increase energy.

After the oil casing inspection is completed, the required thickness detector is completely covered, and the ultrasonic thickness detection system is installed after general testing equipment (for example, magnetic flux leakage detection system). Under the conditions of parameters, adjust the angle of the probe to determine the rotation speed of the rotating motor and the scanning speed of the oil casing.