Catastrophic Failure Analysis of HP Urea Scrubber

This case study examines the catastrophic failure of a high-pressure (HP) scrubber in a CO2 stripping urea plant, which occurred in 1998 after 17 years of operation. The incident involved the rupture of the scrubber's dome, resulting in significant damage to surrounding infrastructure. Initial hypotheses suggested an explosion due to a hydrogen-ammonia-air mixture or mechanical deterioration of the dome. However, analysis determined that the failure was caused by severe corrosion of the inner carbon steel layers, which was due to ammonium carbamate leakage through a defective weld in a cover plate. This corrosion went undetected because a leak detection hole was plugged during commissioning, disabling the system. The study emphasizes the critical need for effective leak detection systems, robust welding practices, and diligent maintenance protocols to prevent such incidents in high-pressure urea production facilities. The findings highlight the risks associated with ammonium carbamate corrosion and the importance of adhering to stringent operational standards.