Five Questions about Rotor Inspections and Repairs

The rotor is one of the most critical components of any turbomachine.  A rotor is subject to many factors that influence its condition, such as gases or steam, vibrations, pollution, abrasive parts in the medium, temperature variations and starts/stops. Over time, these factors will lead to erosion, corrosion, cracks or even broken parts.

Rotor inspections can detect faults at an early stage and repairs can prevent unplanned outages. That is why rotor inspections are an essential part of maintenance programs for turbomachinery.

We regularly receive questions about rotor inspections and repairs and hope to answer the most frequently asked questions below.

Did you know that Maintenance Partners performs rotor inspections according to the API687 standard?

To ensure the quality of rotor inspections and to clearly define the contents of a rotor inspection, Maintenance Partners has implemented the API687 for rotor inspections of centrifugal compressors, axial compressors, steam turbines, gears, expanders and positive displacement rotary screw type compressors.

What is API687?

The API687 standard has been drawn up by American Petroleum Institute and is a recommended practice for repairing rotors. API687 is the only written standard covering rotor inspection and repairs in all aspects and defines what vendor and equipment owner responsibilities are during the inspection/repair process. Inspections and repairs generally follow the following sequence:

During the entire process the equipment owner has the lead for approving job scopes, work procedures, welding procedures and quality plans. The vendor shall have all details of repairs, material certificates and records of heat treatments available for the equipment owner.

API divides the inspection process into two phases:

  • Phase I, Inspection: Assembled Rotor
  • Phase II, Inspection: Disassembled Rotor
  Phase I inspection Phase II inspection
Unload and unpack rotor
Conduct incoming visual inspection
Protect all critical areas & clean by glass peen blasting
Perform visual inspection after cleaning
Perform NDT
Check and record dimensions, electrical & mechanical runouts
Perform low speed balancing check
Prepare Phase I inspection report
Disassemble rotor (blades or impellers)
Perform visual inspection of all removed parts
Measure all shaft component sizes
Perform NDT on all removed parts
Prepare Phase II inspection report


How is API687 implemented at Maintenance Partners?

Embedding the API687 workflow in our ISO9001 procedures has resulted in standardization in sales and operations. Maintenance Partners uses standard job scopes, quality plans, procedures and reporting templates.

What if a rotor needs to be repaired?

Maintenance Partners’ rotorshop is fully equipped with state of art equipment for all types of rotors. Depending on the condition of the rotor, the rotor repair may include the following:

  • Rotor journal repairs by welding, laser cladding or HVOF coating
  • Spare parts: manufacturing of new impellers, shafts, blades, diaphragms, blade carriers, etc.
  • Reblading
  • Replacement of seal strips
  • Low speed balancing
  • High speed balancing
  • Over speed test
  • Impeller spin test
  • Coating application on compressor impellers for corrosion protection, reduction of fouling rates and a smooth surface, resulting in an increased efficiency

Are spare parts for rotors available?

Lead times of parts can be very long. To overcome this, Maintenance Partners offers reverse engineering. Our engineering capabilities enable us to carry out the entire re-engineering process internally. From scanning, redesigning and modeling to manufacturing. We supply blades, shafts, rotor discs, single impellers as spare parts, but also completely assembled rotors.

Our spare parts are manufactured according to the most stringent standards and are 100% compatible. We combine the highest standards of turbo machinery knowledge with an in-depth understanding of material specifications, manufacturing standards and tolerances:

  • Fast delivery
  • Inhouse engineering
  • Inhouse manufacturing
  • Inhouse high speed balancing
  • Onsite installation & commissioning

More information

For more information, please visit the pages about rotor repairs and reverse engineering of parts on our website. You can also call us at +32 (0)3 541 71 40 or send us a message using the form below:

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