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Plate Heat Exchanger Leak — Refrigerant and Chilled Water Cross-contamination

Likely causes

Micro-cracks in brazed plates

Check: metal fatigue from repeated thermal shock (start/stop cycles)

What to do: Cross-check pressures on refrigerant and chilled water sides — look for refrigerant bubbles or oil in chilled water circuit to determine contamination direction

Degraded/hardened gaskets in gasketed plate type

Check: loss of sealing

What to do: Pinpoint leak location in brazed plate — drain chilled water, pressurize refrigerant side with nitrogen (0.7 MPa), and detect bubbles on plate surface

Corrosion of plate material from excessive acidic descaling chemicals on chilled water side

Check: Inspect with instruments or visually

What to do: Replace entire unit if brazed plate is damaged (single-plate repair not feasible; re-brazing is temporary and typically recurs within 6 months)

Abnormal pressure rise on refrigerant side

Check: cracks from instantaneous overpressure due to repeated high-pressure trips

What to do: For gasketed type leaks — re-torque all bolts to manufacturer spec uniformly, replace full gasket set, and reassemble

Non-uniform bolt torque causing plate deformation

Check: localized leaks in gasketed type

What to do: After descaling chilled water side, measure pH and chloride level; readjust water treatment chemical concentration

Field tip

Early sign of plate cross-contamination: refrigeration oil smell (rotten egg or mineral oil odor) in chilled water piping or oil film on chilled water tank surface — inspect immediately.

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