On aged machines significant power savings can be achieved with upgrades to modern impellers optimized by latest CAD/CAE methods to fit client gas specific parameters and deliver superior aerodynamic efficiencies.
Often integrally geared compressors can be upgraded by adding inlet guide vanes (IGV). If compressor is operated for prolonged periods at partial-load with suction throttling , IGV investment costs can be quickly returned by significantly reducing adsorbed power.

We can provide complex support from initial feasibly assessments up to detailed manufacturing documentation. See more details on compressor flow path rerates in section Energy savings.


Sometimes the original couplings are not market available anymore or user prefers to replace gear couplings by modern flexible type couplings. Often driver modernizations require also coupling replacements. Flexible couplings usually brings lower mass and somewhat increased inertia compared to gear types. While inertia changes are usually not critical, mass reduction may often have impact on lateral dynamics peformance.

RotMach can provide guidance on coupling replacements. Our evaluations include design packaging and API compliant compressor/driver lateral analysis and torsional rotordynamics analysis to confirm coupling compatibility and expected effect on overall machinery vibration levels.


In some cases, original bearings for centrifugal compressors cannot be obtained and replacement solution is needed. Wide range of aftermarket solutions is normally available. But replacement bearings should be carefully selected to not have detrimental effect on overall rotor dynamics (machine vibrations) under full spectrum of operating and transient conditions.

We can provide bearing design packaging and comprehensive lateral rotor dynamics analysis before bearing installation to ensure successful upgrade and reliable, problem free operation.


With current trends of Industry 4.0 and improved preventive maintenance strategies older compressors are frequently being upgraded with modern condition monitoring systems such as relative vibration eddy current probes.

We are ready to furnish such upgrades including:

– structural (FEM) validation of housing mechanical modifications
– custom eddy current probe holders
– shaft modifications with run-out bands specifications
– detailed design up to manufacturing drawings
– PID documentation


Significant part of energy costs can be saved by replacing old electric motor with a new one, return on investment can be in just few years.
In some cases, older gas turbines are increasingly difficult and expensive to maintain properly. Turbines are often operating in variable speed drive (VSD) mode, so replacements with VSD electric motors & frequency converters are typical solution. Return on investment is generally good, depends on available power connections and machine utilization through year.

We can furnish detailed API compliant torsional analysis for replacements of gas turbines by VSD electric motors with frequency converters. We can provide detailed baseplate designs with necessary structural analysis and auxiliary systems including lubrication & piping system designs.