Rotating machinery and especially centrifugal compressors typically provide long lifetime. It is no exception that if well maintained, several decades old machines are in service without major issues. Users may favor to keep such machines running, however sometimes spare parts are not available or the use of original parts would be a limiting factor in total ownership costs evaluations. Progress in modern 3D scanning methods has allowed for highly cost-efficient reverse engineering of components and created whole new options for spare parts manufacturing.



However, in many cases more advanced engineering including in depth knowledge of design & analysis of rotating parts is needed. This is where RotMach expertise provides real value to our clients. We are ready to support on both planned & emergency repairs. If needed, we can advise on compliance with API standards such as API 617 or API 687 for rotor repairs.



We can also provide engineering support on rotor balancing, especially for flexible rotors where often in-depth understanding of rotor mode shapes and bearing properties is required to successfully meet stringent rotor residual unbalance and machinery mechanical vibration limits. 



We have experience with various repairs of centrifugal compressor components. We can carry our detailed structural, flow and vibration analysis to validate both planned and emergency repairs.

Sometimes shaft close clearance locations (such as surface under seals, bearings etc.) experience rubbing events and consequently surface renewal is required. Minor damages can be simply grind off and possibly metal sprayed, larger damages are fixed my means for shaft sleeves, if feasible.

RotMach can evaluate effect of such repairs on rotor vibrations (lateral dynamics analysis) and stress / fatigue life.

Impellers (especially open type) can be damaged to a point where large sections of all blades are missing and 3D scanning cannot provide full geometry anymore.

By utilizing 3D CFD analysis we can confirm if CAD geometry restorations provide similar thermodynamic performance (pressure ratio etc.) to original design.

We can also provide in-depth expertise for impeller dynamics (SAFE diagrams) for cases of altered manufacturing methods (for example replacement of riveted impellers). For rotors experiencing vibrations issues we can provide engineering support for balancing and complex rotor dynamics.




Thanks to our specialization on integrally geared compressors (IGC) we have also in-depth knowledge of high-speed gearboxes. Shaft sleeving, bearing & seal surface restorations, impeller interfaces (Hirth connections) are typical repairs carried out on gearbox shafts. With overhung impellers and typical operating speed above 1st or 2nd critical, IGC shaft can be prone to increased vibrations if not balanced by correct methods. We can provide technical support on balancing issues (low speed, high speed, sequential).


We can readily provide support on repairs and vibration problems of IGC and high gearboxes. We are ready to upgrade gearboxes with relative vibration probes, see more details in Upgrades & modernizations.



If you are involved with major structural rotor repairs, shaft sleeves etc. we can provide technical support and reviews by means of static and dynamic FEM structural analysis.


We have experience with repairs from compact air end units up to large process screw compressors.


Shaft sleeves, and surface repairs are common also for electrical machines rotors. Centrifugal forces and uneven thermal filed can induce complex stresses that should be understood and respected while carrying out electrical machines advanced rotors repairs (retaining rings, fans etc.)

These are typical tasks for application of 3D FEM structural analysis.



Sometimes larger repairs / modifications or coupling replacements are performed on reciprocating compressors.

We can support workshop repairs of main components – crankshafts, piston rods, housings etc. with structural 3D FEM analysis.

With larger parts modification, sometimes in order to avoid vibration problems complete drivetrain torsional analysis should be also performed. If sufficient compressor data are available, RotMach is able to perform torsional analysis to evaluate possible effect of components modificatons.