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Failure Analysis Case Histories
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Pitting of Copper in Heat Exchanger System
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EQUIPMENT:
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Heat Exchanger |
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ENVIRONMENT:
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Water |
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MATERIAL: |
Copper |
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SERVICE TIME:
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Unknown |
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FAILURE:
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Pitting Attack |
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Copper tubing with aluminum fins was employed in a heat exchanger system.
Temperature was controlled by circulating water through the copper tubes. Pin
hole leaks were observed in the copper tubing at the time of failure. |
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Cutting the tubes in half longitudinally revealed extensive corrosive attack,
primarily pitting on the inside diameter (Figure 1). |
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SEM (scanning electron microscope) equipped with EDS (energy dispersive x-ray
spectroscopy) was used to identify the elemental components of the various
corrosion products observed. A high level of chlorine along with lower levels of
sulfur and iron were detected. |
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Corrosive attack was due to a high level of chloride and sulfur compound most
likely present in the water. The presence of iron indicates contamination due to
corrosion occurring elsewhere in the system. |
