Acoustic emission monitoring during hydrotesting of a mounded LPG storage vessel of petrochemical industry

One mounded LPG storage vessel of petrochemical plant got suddenly exposed to cryogenic nitrogenand developed cracks in the shell plate adjacent to the bottom nozzle and was subsequently repair welded.The structural integrity of the repair weld region was assessed by NDT examinations. The integrity of there paired weld region was conrmed by conducting hydrotest. Acoustic emission (AE) monitoring during thehydrotest was also carried out. The acoustic emission signals generated during the hydrotest indicated thatthe signals were due to structural noise and microyielding of the vessel material. During the repressurizingcycle of the hydrotest, negligible AE signals were generated and this conrmed the structural integrity of therepair welded region of the vessel monitored by acoustic emission technique (AET).