Tuesday, March 24, 2009: 9:30 AM
C304 (Georgia World Congress Center)
OCR Reactors in Atmospheric Desulphurization Unit (ARDS) of Mina Abdulla Refinery are provided with 4” dia X sch. 160 Tp321 S.S piping for draining of reactor material during shutdowns to low pressure section. A total of 3 on-stream failures occurred on the weld/parent metal and caused unit shutdowns/SHE hazards. Failures occurred in the form of extensive multi branched cracking in the parent metal / welds / HAZ. Failure was itiated by the presence of high level of chlorides and due to poor weld quality and mismatch of thickness between 90o elbow/ pipe. The high pressure in the pipe , presence of high levels of chlorides in the stagnant section of pipe and low temperatures in the stagnant section of the pipe has aggravated the situation, which resulted in typical catastrophic Chloride Stress Corrosion Cracking (SCC) failure.