Study On The Ultrasonic Testing Technology Of Drill Pipe Upset Transition Area

Oil drill pipe is an important tool in the drilling work,and the tube body and the joint is connected by butt welding.In order to enhance the strength of the joint,both ends of the tube body need to be thickened.The drill pipe works under various loads,and it contains many kinds of corrosive medium in a high temperature and high pressure environment.Thickened transitional disappeared zone easy to produce stress concentration,and prone to defects in corrosive environment.So it causes significant financial losses for the drill pipe failure.Non blind detection of oil drill pipe upset transitionzone ensure the safety and efficiency of the drilling work.The paper has completed the design and processing of ultrasonic transducer and water immersion focusing probe according to the characteristics of the two kinds of probes designed coupling device.And Ensure the accuracy and precision of ultrasonic testing system's test results by experiments.The emissive frequency of normal probe is 5MHz.The piezoelectric material is PZT-5X and the wafer diameter is 8mm.The material of damping block is epoxy resin and tungsten powder.The protective film is made of plexiglass.The protective film of normal probe is made curved surface,and the curvature is the same as the outer surface of the drill pipe.With the increase of the transmission frequency,the directivity of the sound beam becomes better,and the length of the near field region increases after analyzing different frequency(2MHz?2.5MHz?3MHz and 4MHz)simulation of circular transducer ultrasonic field.The focus probe is used to converge the ultrasonic wave through an acoustic lens,and the material of acoustic lens is plexiglass.Simulate the internal flow field coupling device.The water entering the internal flow field of the coupling device can fully flow.The pressure of lower area of probe is stable.The water can excluded from the probe and the surface of the workpiece,and it enhances the effect of coupling.The accuracy of ultrasonic detection system detection results is high by testing the standard test blocks,and the largest error is 0.1mm.The test results are accurate and can meet the actual needs by using the common direct probe to test the drill pipe and pipe in the field.By testing the step test block and the inclined test block with immersion focusing type probe,the result can reflect the shape of the test block by analyzing the test data.