The contact condition of the sealing surface of premium tubing has a significant impact on the seal-ing performance.The different contact conditions of the sealing surface are difficult to be comprehensively evaluated only by the reflection coefficient in the ultrasonic reflection amplitude stress technology.Therefore,in the paper,by means of collecting the phased array ultrasonic images of tubing sealing surface under different torques and with-out threaded compound as well as extracting the texture features of the images,the qualitative and quantitative rela-tionship between texture feature parameters and different contact conditions was analyzed.The research results show that as the torque of tubing increases,the greyscale mean,greyscale variance and skewness of the ultrasonic image all decrease;the paragenetic matrix contrast of the ultrasonic image greyscale of tubing sealing surface shows a lin-ear decrease in the 45°,90° and 135° directions with the increase of tubing torque;in the 0° direction,the con-trast of ultrasonic image without threaded compound is 2.19 times of that with threaded compound at the same torque;the paragenetic matrix entropy value of the ultrasonic image greyscale of tubing sealing surface shows a lin-ear decrease in the 0°,45°,90° and 135° directions with the increase of tubing torque.The research results pro-vide data support for the qualitative and quantitative characterization of ultrasonic detection images of tubing sealing surface under different contact conditions.
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