In April 2010, Urea Plant’ operating staff indicated vacuum losing in Separator (324F001) which reduced urea quantities obtained from urea recovery process and increased the washing rate of granulation unit (production time loss). This paper presents how the damages were detected, damages description, problem root cause analysis, remedies executed and conclusion. 

Observed damages were had the following characteristics: 

1. No previous experience was recorded for this problem in similar local operating plants. 

2. External on-steam inspection (by inspection, operation and maintenance staff) was not indicating any problem seriousness.   

3. Internal off-stream inspection indicating severe chemical corrosion attack of carbon steel parts as well as severe longitudinal separation cracks follows the fusion line of welding seams in both of SS internal liner and external welding of CS flange. 

4. If the corrosion was propagated more than observed damages, it could lead to catastrophic disaster, falling of Evaporator (consequences could be: personnel death/injuring, damaging of other equipment/piping, environmental pollution, production interruption….etc).