As part of a routine maintenance program, a scheduled overhaul was planned for a Mitsubishi centrifugal compressor. Approximately one year prior to the overhaul, the customer supplied a new spare rotor and associated components to the Blackstone Repair Services shop for inspection. Following completion of the inspection, the rotor was returned to the customer’s site and stored until required. 

In April 2026, the compressor was removed from service by the Blackstone Field Services Team and transported to the Blackstone shop for overhaul. Upon arrival, the field services team assisted with the removal of the bearings and seals before transitioning the project to the Blackstone repair team. Following this initial work, responsibility for the overhaul was transferred to the Blackstone team, which carried out the remaining disassembly, cleaning, inspection, repair, and reassembly activities. 

The overhaul was executed under a compressed outage schedule and involved extensive inspection and verification activities to ensure the compressor was returned to service in optimal operating condition. Through close coordination between field and shop personnel, the project was completed successfully and delivered on schedule. 

Above: Bundle as received

• Complete disassembly of the compressor 

• Chemical cleaning of all components using specialized cleaning processes 

• Borescope inspection of the compressor bundle and flow path components 

• Non-Destructive Testing (NDT) carried out on the bundle to verify its integrity and identify any indications requiring further evaluation  

• Inspection and evaluation of all internal components 

• Following completion of the inspection activities, the unit was reassembled using the new spare rotor and associated parts that had been previously inspected. 

• Verification and documentation of all dimensional and running clearances 

• Establishment of rotor running position in accordance with OEM requirements 

• Complete reassembly of the compressor to conclude the overhaul 

Above: Balance Testing & Assembly

1. One of the primary challenges involved cleaning the compressor bundle. Due to the sensitive nature of the internal components, conventional abrasive cleaning methods such as sandblasting could not be utilized. To effectively remove deposits while protecting the component surfaces, a specialized cleaning process was developed using an industrial-strength vinegar solution containing 7.5% acetic acid. This approach successfully restored the cleanliness of the bundle without risking damage to critical surfaces.  
2.  Another significant challenge was the handling and installation of the dry gas seals. The dry gas seal assembly required careful alignment throughout the installation process, as any misalignment of the seal could result in contact between the seal components and the shaft. Such contact could damage the shaft surface and compromise seal performance. Due to the precision required, the installation process was particularly time-consuming and demanded meticulous attention to alignment and handling procedures.  
3. The project also presented supply chain challenges related to sourcing the replacement hardware and seal materials required for the overhaul. The compressor utilized metric fasteners and a proprietary seal material critical to the internal sealing system, neither of which was readily available through local Canadian suppliers. To prevent delays to the outage schedule, the team conducted an extensive search across multiple suppliers in Canada and the United States. After an extensive sourcing effort, a U.S.-based supplier was identified that could provide the correct hardware specifications and sizes within the required timeframe. Through effective supply chain coordination and procurement management, the project remained on schedule.  

Above: Preservation & Packaging

• Successful completion of the overhaul within a compressed outage schedule allowing the customer to meet a critical outage deadline and return the compressor to service on time 

• Minimized production impacts through efficient project planning, coordination, and execution 

• Improved reliability and readiness through the installation of a pre-inspected spare rotor 

• Comprehensive inspection and testing to verify equipment integrity and performance 

• Reduced outage risk through proactive sourcing and supply chain management 

• Highest standards of quality and workmanship while maintaining aggressive turnaround requirements 

• On-time return to service to support operational objectives 

This overhaul represented the first Mitsubishi compressor service project completed by Blackstone Repair Services. The project was performed under the oversight of Mitsubishi management, a third-party technical advisor, and the customer’s engineering representative, providing a high level of technical scrutiny throughout the process. 

The successful execution of the overhaul demonstrated Blackstone’s ability to deliver complex OEM-equivalent repair and maintenance services while meeting demanding outage schedules and quality expectations. The successful execution of the work resulted in positive feedback from all stakeholders, who expressed confidence in Blackstone’s technical expertise and service quality. As a result, Blackstone was identified as a preferred service provider for future Mitsubishi compressor repairs and overhauls.