TOFD Inspection of Welds in Spherical Tank in-Service

A detection scheme based on flight diffraction (TOFD) and manual ultrasonic testing (UT), as well as magnetic particle testing (MT) was designed to detect butt welds in oxygen tank in-service.MT was used for the compensation detection to TOFD testing blind spots which are in the top and bottom surface of weld.Using UT re-inspects the defects which were detected by TOFD, Additionally, the results were compared with X-Ray testingresults.The results is that TOFD detects many intensive stomatal defects, one of them is serious and does not meet the qualificationrequirements.However, UT and MT only detect one stomatal defect, which also does not meet the qualificationrequirements.It showed that TOFD is more efficiency compared to other NDT methods, at the same time, it also confirmed that the detection scheme was feasible.