| The basic working principle of Time of Flight Diffraction Technique(referred to as TOFD)is based on the diffraction wave from the probe emitted ultrasonic reflected back in contact with the tip of the defect to detection of pressure vessel equipment.TOFD technology has the characteristics of high accuracy,high reliability and good adaptability to various environments,so it is widely used in the non-destructive testing of pressure vessels.TOFD technology also has some limitations,because the related technology is not perfect,resulting in map evaluation prone to miscarriage of justice and Missing,making its stability.In this paper.TOFD technology for pressure vessel defects in the study of the problems faced by the study,has important theoretical significance and engineering value.The main contents and results are as follows:(1)The working principle of TOFD detection technology is introduced,the detection theory of TOFD defect height is expounded,and the imaging method and gray scale imaging principle of TOFD detection imaging and scanning are analyzed.(2)Using CIVA software to build the simulation model.the TOFD imaging process parameters were analyzed.A non-parallel and 45 ° oblique non-parallel joint scanning method is proposed to effectively improve the detection rate of lateral defects.The TOFD detection method is better than the TOFD detection method.(3)Analyze the causes of common weld defects,including cracking,unmelting,non-penetration,porosity,welding slag,etc.of the pressure vessel,and the TOFD characteristics of these typical welding defects are proposed.(4)The specific girth weld is selected as the test object,and the TOFD detection process parameters are set up properly.In order to ensure that the whole weld is fully detected,the joint detection method of 100%TOFD and 100% climbing detection is adopted.Comparison between the two detection results found that climbing detection is very good to solve the TOFD surface area of the impact. |
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