Acoustic emission testing of repaired storage tank

In order to check the structural defects of a repaired storage tank, acoustic emission (AE) signals were monitored during a load sequence of 90-110% maximum operating load range. Then, based on the AE activity indications, subsequent radiographic testing (RT) was conducted. The field AE test results showed the active emissions of weld-like defects and the inordinate emission bursts of mechanical noise signals. The mechanical noise resulting from valve shut-off was characterized by the high-density emissions of high-count events compared with the genuine emissions. Some activity indications were confirmed to be correlated with significant weld-like defects by the follow-up RT, but other emissions appeared to be unrelated to any detected defects. The observed weld-like defects were a through-wall weld crack of 1.5 cm length and a round individual porosity of 0.5 cm diameter, respectively. Under the 110% maximum operating load conditions of the repaired storage tank, the detected defect emissions were active but not characteristic of defect growth. (C) 2001 Published by Elsevier Science Ltd.