Exxon’s South Texas Division operates approximately 100 engine/compressors ranging from 1000 to 3400 hp (746–2535 kW) each. Traditionally, engine frame realignment procedures for these units have been basically trial and error. This paper presents an analytical procedure that eliminates much of the trial and error associated with engine frame realignment efforts by converting crankshaft web deflection readings to a profile of the main bearing shells. The program output indicates both the magnitude and direction of corrections that are needed to reduce any excessive web deflection readings. Raw field data are mathematically smoothed by a curve-fitting routine to provide insight on possible errors which could be easily overlooked in a visual examination of a web deflection survey. This paper addresses the key aspects of applying this approach in both routine evaluation and in major realignment work. Several examples are presented, including one case history showing how computer modeling of a 3400 hp (2535 kW) engine/compressor crankshaft profile permitted new chocks to be custom made before shutdown of the unit for realignment. This reduced downtime for the complete rechocking and realignment from 4 days to 14 h.

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