A major natural gas pipeline operator contacted Rotating Machinery Services (RMS) with a critical challenge: increasing the supply of natural gas to meet rising demand. After a collaborative evaluation of options, the RMS team and the customer determined that refurbishing an out-of-service DeLaval 2B 12/12 centrifugal compressor was the most efficient and cost-effective solution. This compressor had been stored in a boneyard for over 20 years—exposed to the elements and long overdue for a comprehensive overhaul.
Project Kickoff: Mobilizing RMS Resources
The DeLaval 2B 12/12 is a beam-style compressor with inline nozzles, designed to be placed directly in-line with a natural gas pipeline. The complete compressor skid—including the compressor, auxiliary drive gearbox, lube and seal oil systems—was delivered to RMS, where the unit underwent full disassembly and assessment.
The compressor was sent to RMS’s Bethlehem, PA, facility for overhaul, while the gearbox and turbine starter were shipped to RMS’s Houston facility for specialized repair. This coordinated effort allowed RMS to efficiently utilize its nationwide resources and expertise to accelerate turnaround time and deliver top-tier results.
Inspection, Analysis, and a Plan for Renewal
Upon arrival at RMS Bethlehem, the weathered compressor was blast-cleaned and fully disassembled. RMS engineers conducted a detailed inspection, including dimensional data collection and non-destructive testing, to assess the health of each component. These findings were compiled into an inspection report, providing the customer with transparent, data-driven repair recommendations.
Many components were salvageable through expert refurbishment, while others—deemed beyond economical repair—were replaced with newly manufactured parts. Bearings were sent to RMS’s trusted supplier for further evaluation. In parallel, RMS performed a rotor dynamics analysis to investigate previously reported vibration issues and chart a path toward improved performance.
Solving Historic Vibration Problems with Modern Engineering
The analysis revealed that the compressor’s original rotor had a critical design flaw: the second rigid bearing critical speed coincided with the operating speed, resulting in instability and overhang vibration. RMS engineers re-designed the rotor-bearing-seal system using advanced rotor design tools to modernize performance and ensure stability. Key upgrades included:
- Increasing journal diameters and bearing pad lengths for enhanced stability.
- Shortening the shaft thrust end to reduce overhanging mass and improve damping.
- Designing a new low-profile thrust bearing and housing to accommodate the modified rotor.
- Specifying a custom longer coupling to align the shortened rotor with the existing drivetrain.
These changes effectively raised the critical speed well above the operating range, delivering a stable, reliable rotor while reusing OEM impellers—saving both cost and lead time for the customer.
Refurbishing the Compressor and Skid to Like-New Condition
In addition to the re-engineered rotor, RMS also refurbished the outer casing, inner casing, and inlet guide vane assemblies. Every component was stripped down and repaired to better-than-new condition, ensuring reliable long-term performance.
RMS’s overhaul scope extended beyond the compressor to include the complete refurbishment of the skid. Key upgrades included:
- Full disassembly, cleaning, and inspection of all skid components.
- Replacement of carbon steel piping with stainless steel buttweld piping.
- Upgrading all tubing to meet API-614 standards.
- Complete rewiring of the unit with NEC-rated electrical systems.
- Replacement of outdated control and monitoring devices with modern smart transmitters.
- Refurbishment and replacement of pumps, motors, fan bearings, and other auxiliary systems.
- Structural modifications and machining to improve alignment and structural integrity.
Results: Reliable Performance Supporting Critical Infrastructure
Thanks to RMS’s engineering expertise and integrated service capabilities, the refurbished compressor and skid now operate with performance and reliability that exceed the original specifications. The re-designed rotor eliminated systemic vibration issues, reducing maintenance costs and increasing operational stability. The upgraded skid components ensure safe, efficient, and long-lasting service.
The overhauled DeLaval 2B 12/12 compressor is now in operation, supporting critical natural gas pipeline infrastructure and helping meet the growing energy needs of communities across the country.