Copper-pitting corrosion in drinking water has been
the subject of relatively intense research for more
than 50 years. Worldwide, several different water
types are known to support pitting. In Australia, New
Zealand, and some other locations around the world,
however, pitting predominates in soft, unbuffered
waters. The pitting corrosion of copper tubes in drinking
water systems is a sporadic but persistent problem
along, for example, the east coast of Australia.
Historically, the lack of an adequate theory for
localized soft water copper corrosion has made remedial
treatments speculative and based only on longterm
field trials. Even though several pitting models
have been developed over time, the earlier models had
their limitations.
Pitting corrosion of copper in soft water is known to
be dependent on water chemistry, particularly pH and
buffering capacity. The randomness of the problem,
however, along with the large number of chemical and
physical variables involved in its initiation and propagation,
required a better theoretical and practical
framework for understanding more about the essential
components of the pitting process.
For this work, the authors used novel microelectrode
electrochemical techniques, supported by field
observations and thermodynamic calculations, to propose
a new mechanism of copper-pitting corrosion in
soft waters. The proposed model for soft water copper
pitting stresses the dependency of pitting on the formation
of a suitable cathodic film on the tube surface. The
authors also discuss how the proposed theory may be
applied to the development of a remedial water treatment
strategy and used to calculate the optimum pH
and alkalinity set points for a soft water. Includes 19 references, figures.
| Edition : | Vol. 96 - No. 11 |
| File Size : | 1
file
, 370 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 10 |
| Published : | 11/01/2004 |
