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Galvanic Corrosion in Chiller Tubesheets
Galvanic corrosion at tube-to-tubesheet interfaces can cripple chiller performance. Case #035
The Situation
Galvanic Attack at the Tube-to-Tubesheet Interface
A water chiller system experienced heavy corrosion with carbon steel tubesheets suffering severe metal loss at the tube-to-tubesheet interface. The galvanic corrosion was attacking the junction where copper tubes connected to the carbon steel tubesheet, creating the classic dissimilar metal corrosion cell that plagues chiller systems operating with cooling tower water.
The Application
Three-Stage Coating System
Stage 1 — Base Protection
Two-coat immersion-grade epoxy system providing comprehensive base protection with proven resistance to cooling tower water chemistry.
Stage 2 — Metal Rebuild
High-performance metal rebuilding compound applied specifically at tube-to-tubesheet interfaces where corrosion was most severe — rebuilding lost metal profiles while creating a protective barrier.
Stage 3 — Topcoat & Inspection
Fluorescent-pigmented topcoat bringing total protection to 30 mils DFT, enabling easy UV inspection for quality control.
The Result
The tubesheets were successfully protected from galvanic corrosion. The coating system created an electrically insulating barrier that stopped the electrochemical reaction between the dissimilar metals — eliminating the root cause rather than just treating the symptoms.
Industries: Power Generation
Categories: Chiller, Maintenance & Repair
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