Centrifugal compressors can be either a horizontal split case compressor or vertical split case centrifugal compressors. The type of case used will depend on the pressure rating. Vertical split casings are generally used for high-pressure applications. In vertical split case compressors, the barrel present in the compressor uses a vertical split construction, which is manufactured, in an integrally geared configuration. This compressor is basically an over hung style machine mounted on a gearbox and uses the gear pinion shaft extension to mount an impeller. The casing of the compressor is also attached to the gearbox and this style is built in both the single and the multistage configuration of vertical & horizontal split case centrifugal compressors.