Key Issues On T、K、Y Tubular Joint With Ultrasonic Phased Array Technology

T,K,Y tubular joint is one of the most important type of the steel structure, whosequality have been paid more and more attention. For these welds, people commonlyuse transverse wave probe to detect. However, the probe is needed to move frequentlyor even replaced during the operation of the detection. In addition, there are so manysteps and time to check defects by manual drawing, which are unfavorable to theinspection. In order to improve the detection efficiency and avoid positioningdifficults of T,K,Y, this paper mainly adopts the ultrasonic phased array inspectiontechnology and computer-aided technology to research this type of welds. The paperaims to solve the key issues of bigger blind area, difficult defect recognition and slowpositioning speed in the conventional inspection. The main contents summarized asfollows:Firstly, theories of ultrasonic phased array technology and the sound field of alinear array probe have been researched. The author derived delay algorithm ofultrasonic phased array shear wave detection, and proposed "equivalent" elementconcept.Secondly, based on the analysis of the structural features of T,K,Y, the authorestablishes the mathematical model of space tubular joint, the weld joint model, thephased array beam coverage model, which aims at simulating the profile of weldand the range of beam coverage in the weld joint. According to the above models,defect recognition and positioning method is established.Subsequently, those models of T、K、Y by the use of computer-aided technologyhave become a set of software, which is compiled by Visual Basic. This software canachieve to draw the cross-section of weld quickly, display the beam coverage vividlyand locate the defeats in the welds. With this software, the inspection craft of T,K,Yusing ultrasonic phased array have been designed in the paper.Finally, a specimen of Y tubular joint weld is designed on the basis of offshoreplatform characteristics. The experiments of imaging and rapid defect location havebeen done with the equipment of ultrasonic phased array. Positioning precision isanalyzed afterward.The results of the study show that it is beneficial to improve the detectionefficiency of T,K,Y with ultrasonic phased array inspection technology, and to reducethe movement of the probe in conventional way. To a certain extent, those models based on "drawing-analytic method" could simulation the real cross section of T,K,Y.Computer-aided software can be used to guide parameters settings of ultrasonicphased array, and achieves the fast drawing of weld section, signal identification,quick-location defects. Tests of artificial horizontal hole suggests that defect locationerror is less than2mm. Testing methods and means used in this paper meet thedetection requirements of T, K, Y. Meanwhile, efficiency is improved significantlyand this is beneficial to the development of intelligence to this kinds of welds.