Multiple Tube Failure of Crude Distillation Unit Offgas Inter Stage Coolers

Abstract Crude Distillation Unit (CDU) consist of off-gas compressor which is a two-stage centrifugal machine type with inter and after cooling exchanger. Off-gas from the Pre-flash Column, Atmospheric Column and Vacuum System Liquid ring compressor is combined in the CDU off-gas compressor suction drum. Any condensate or liquid carried over is separated from the gas and pumped with the off-gas compressor suction drum pumps to the discharge line from the second stage. During the analysis of cooling water refinery wide the CDU off-gas compressor inter stage coolers were identified as prime source in impacting the quality of cooling water. These exchangers were offered further for inspection and found with multiple number of tubes failure. The external surfaces of these tubes were fully found with heavy amount of deposits surrounded all over the tube bundle. Considering above mentioned factor detail failure analysis was conducted to established root cause for multiple failure of tubes by the help of multi-disciplinary team to prevent similar failure within facility for different units. This paper will outline the significant efforts undertaken throughout the failure analysis in order conclude the direct root cause, contributing factors, mitigation, preventive measure and other control techniques. This paper will provide significant information to the industry to avoid similar failure in near future either existing or new constructional facility.