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Dezincification of Brass Heat Exchanger


Slightly Alkaline Water


Heat Exchanger


Plug Type Dezincification


This heat exchanger experienced failure due to cracking of the heat exchanger tubes. A dark red/black deposit covering the ID contained several locations with cracks or pits (Figure 1).

A cross section was made of a typical pitted area. The ID pits were filled with a deposit and contained cracks growing from the bottom of the pit (Figure 2). This cross section was examined using energy dispersive x-ray analysis (EDS). EDS clearly showed that the pits were the result of dezincification.

Conditions favoring dezincification are: contact with slightly acid or alkaline water, not highly aerated, low rates of flow of the circulating liquid, relatively high tube-wall temperatures, and permeable deposits or coatings over the tube surface.

Figure 1. Crack on the ID of the copper tube Figure 2. Dezincification plug (100X Original Magnification)

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