API standards stipulate that the inner and outer surfaces of inlet and outlet oil casings must be free of folds, separations, cracks, and scratches. These defects must be thoroughly removed to a depth not less than 12.5% of the nominal wall thickness. Oil casings must undergo full-coverage automated wall thickness measurement. Currently, there is an indirect method for measuring oil casing wall thickness based on the principle of magnetic leakage. It does not directly measure the wall thickness but rather indirectly measures it by measuring the magnetic field changes caused by variations in the oil casing wall thickness.
Therefore, magnetic field strength has a significant impact on the accuracy and resolution of oil casing wall thickness measurement, making it unsuitable for online automated inspection. Magnetic ultrasonic testing does not require coupling agents, but it is difficult to excite ultrasonic waves in oil casings with uneven surfaces. Industrial ultrasonic phased array probes are expensive to manufacture and have complex systems. Currently, such equipment is rarely seen in my country.
Based on the principle of ultrasonic measurement of oil casing wall thickness, oil casing manufacturers have analyzed focusing probes suitable for automated oil casing inspection. By selecting appropriate focal lengths and crystal sizes, a full-coverage automated wall thickness measurement system has been constructed, resulting in significant improvements within the full coverage range. The design and selection of the probe are crucial to the thickness of the oil casing. Generally, the circular crystal plate of the probe emits an acoustic beam with a certain diameter, which expands with increasing distance. Selecting the right acoustic beam involves focusing it locally through an acoustic lens to increase energy.
After the oil casing inspection is completed, the required thickness detector is completely covered. The ultrasonic thickness detection system is typically installed after testing equipment (e.g., a magnetic flux leakage detection system). Under the specified parameters, the probe angle is adjusted, and the rotation speed of the rotary motor and the scanning speed of the oil casing are determined.
Post time: Dec-08-2025