A system of compressors powered by surface condensing steam turbines is inherent in the operation of a typical ethane cracker unit. These turbines run by extracting work from high-pressure steam, while a surface condenser condenses the turbine’s exhaust to both maximize compressor horsepower and recover valuable condensate. In an ethane cracking unit, a troubleshooting study was undertaken to investigate an inter-after condensing unit and vacuum instability in the surface condenser. The troubleshooting study, summarized in this article by Graham, consisted of field observations, equipment review, trial runs and data collection. Click to see the complete details of the study and what it discovered.