CASE STUDY: Extending Chiller Life Through Condenser and Evaporator Tube Rehabilitation
The Challenge
A large northern New Jersey medical facility's water-cooled centrifugal chiller was experiencing declining performance and increased maintenance issues. Based on MSC's proven track record and trusted relationships at sister facilities within their healthcare system, the facility management team selected us to perform a comprehensive assessment of their chiller's condition before deciding between costly emergency repairs, major rehabilitation, or complete replacement.
MSC's Diagnostic Approach
Our first step was comprehensive tube analysis using Eddy Current Testing (ECT) on both the condenser and evaporator tube bundles. This non-destructive testing method allows accurate assessment of tube wall thickness and identifies corrosion without dismantling the equipment.
Condenser Tube Analysis (300 tubes total)
Eddy Current Testing revealed significant deterioration in the condenser tubes:
213 tubes showed less than 10% wall thickness loss—acceptable
39 tubes had 10-20% wall thickness loss—monitoring required
9 tubes showed 21-34% loss—intermediate concern
8 tubes had 35-49% loss—approaching failure
31 tubes had 50% or greater loss—replacement required
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​Evaporator Tube Assessment
ECT indicated that the evaporator tubes were in much better condition, with 145 tubes showing minimal corrosion and only 3 requiring monitoring. No immediate action was recommended for the evaporator system.
Condenser ECT results
Evaporator ECT results
Our Strategic Recommendation
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Rather than replacing the entire chiller—a major capital expense with long lead times—MSC prescribed targeted rehabilitation:
1. Condenser tube replacement of the 48 most deteriorated tubes to restore heat transfer efficiency
2. Epoxy coating application to tube sheets to prevent future erosion and corrosion
3. Continued monitoring of evaporator tubes through annual ECT as part of preventive maintenance
The Rehabilitation Process
The condenser tube replacement involved systematic extraction of all existing tubes while maintaining the integrity of the shell and internal components. The 48 condenser tubes were replaced using controlled expansion and industrial adhesive, followed by comprehensive quality verification. The end bells were then protected with a specialized multi-layer epoxy coating system applied under controlled environmental conditions and tested for coating thickness, coverage, and adhesion.
Pressure Testing Reveals Hidden Evaporator Issues
Once the condenser rehabilitation was completed, we pressure-tested the condenser tubes and they passed all pressure specifications with no detectable leaks. As part of our thorough approach, we also pressure-tested the evaporator tubes. Unexpectedly, the pressure testing revealed leaks in the evaporator tube system that the ECT had missed.
Upon further analysis by our technicians, we found that the leaks were occurring at the tube ends where they were sealed—an area that eddy current testing cannot effectively assess. We immediately showed these leaks to the customer and recommended replacement of all evaporator tubes and epoxy coating of the evaporator end bells, which they accepted.
Complete Solution
What began as a condenser-focused rehabilitation became a comprehensive chiller restoration, addressing both visible and hidden deterioration throughout the system. This comprehensive rehabilitation approach provided the customer with:
• Significant cost savings: Tube replacement cost approximately 70% less than chiller replacement
• Improved efficiency: New tubes and protective coatings restored heat transfer performance
• Extended equipment life: Retubing can provide 15-20 years of additional service
• Verified reliability: Pressure testing ensured no hidden leaks that could cause future failures
• Future protection: Periodic ECT monitoring prevents future surprises
The Bottom Line
This case demonstrates the importance of comprehensive testing beyond standard diagnostics. While eddy current testing identified the obvious condenser issues, pressure testing revealed critical evaporator problems that would have caused future failures. Through advanced diagnostics, strategic rehabilitation, and thorough verification testing, this customer transformed a potential equipment crisis into a planned maintenance success. Their chiller now operates like new at a fraction of replacement cost, with complete confidence in its reliability.
Key Takeaway
Sometimes the most thorough diagnostic approach reveals issues that individual testing methods miss. MSC's commitment to comprehensive testing—including pressure testing even when ECT results look good—ensures customers get complete solutions rather than partial fixes. MSC's combination of diagnostic expertise, thorough testing protocols, and engineering support enabled us to provide a comprehensive solution that maximized this healthcare facility's equipment investment while ensuring reliable operation for years to come.