Assessing Reliability of Testing Welded Joints of Steel Tank Walls Using Ultrasonic and Eddy Current Methods

The results of the combined application of ultrasonic and eddy current flaw detection to increase the detectability of surface cracks in welds of small thicknesses are considered. A statistical analysis of the noise parameters generated by the reinforcing beads during eddy current testing is carried out. The useful signal-to-noise ratio was evaluated when identifying transverse cracks of operational origin emerging to the surface in vertical and horizontal butt welds of the steel tanks wall. Welds made by manual arc and semiautomatic submerged arc welding are considered, including the most critical areas of the crossings of these welds. For such welds, the reliability of combined ultrasonic and eddy current testing was evaluated when detecting surface and internal longitudinal and transverse cracks compared with the results of radiographic and magnetic particle testing. The prospects of using a combination of methods in the tanks diagnosis as part of ultrasonic testing to detect cracks in the cross section of butt joints and their crossings and eddy current monitoring to detect surface cracks against the background of weld beads are demonstrated.