THE BASIC ASPECTS of the theories proposed by North and Pryor (12) and Gaparini et al.(14) to explain the growth of a protective lepidocrocite layer on the surface of copper and its alloys exposed to seawater conditioned with ferrous salts, and the approach dealing with a heterogeneous reaction occurring through an electrochemical path, are discussed. Some general considerations concerning the physical meaning of aluminium brass corrosion monitoring are developed, and the usefulness of performing in-field measurements to detect anomalous situations during the operation of steam condensers cooled with seawater is carefully examined in order to check the actual validity of information produced using suitable electrochemical techniques. The monitoring system, constituted by three- and five-electrode probes and a computerized corrosion rate meter, installed on the steam condensers of two units of an Italian power station, is described in detail. Concise considerations concerning the computer program developed to control the operation of the corrosion meter and collect experimental data are also given. Some data obtained from the electrode probes installed on the tube sheets of the pass of the Unit 3 condenser are examined in detail to establish empirical guidelines for an optimal injection of Fe2+ ions seawater. Finally, experimental data collected during a three-year period were rather useful for proper operation of the ferrous chloride injection system, for defining the optimal length of the continuous seawater treatment, detecting failures of the protective film, and carrying out discontinuous conditioning operations.
In-field corrosion rate monitoring of copper-aluminium alloy 687 in seawater
Corrosion Prevention and Control ; 51 , 2 ; 43-54
2004
12 Seiten, 22 Quellen
Aufsatz (Zeitschrift)
Englisch
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