R-Pro › Field cases › Cooling towers
Steel Structure/Pipe Corrosion — pH Management Failure
Likely causes
Acidic operation below pH 6.5 — iron ion dissolution and uniform corrosion
Check: Measure pH precisely with digital meter (exclude test strips with ±0.5 error) — below 6.5 = immediate neutralization needed
What to do: Immediately adjust circulating water pH to target 7.5–8.2 — dose NaOH or soda ash → molybdate 10–20 ppm or zinc/phosphate combination treatment
Dissimilar metal contact — galvanic corrosion (copper/aluminum fins and carbon steel)
Check: Visually inspect dissimilar metal contact areas — check for pitting or concentrated reddish-brown rust
What to do: Isolate dissimilar metal contacts with insulating gaskets or plastic bushings → grind corroded areas and repair with epoxy coating or zinc spray
Excess chlorine dosing (residual Cl₂ >1.0 ppm) — induces pitting on stainless surfaces
Check: Measure residual chlorine — above 1.0 ppm = pitting risk on stainless; visually inspect stainless parts for pitting
What to do: Maintain residual chlorine 0.3–0.8 ppm → verify auto-dosing system settings → patch existing pitting with epoxy temporarily, then plan long-term replacement
Field test strips have ±0.5 pH error — calibrate a digital pH meter monthly and use it for precise readings.
All 565 cases work offline in R-Pro, with error codes for 62 brands and P-T data for 108 refrigerants.
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