Abstract
After a concise survey of the two theories, suggested by North and Pryor and by Gasparini et al., for explaining the formation of a protective lepidocrocite layer on the surface of copper and its alloys when they come in contact with sea water conditioned with ferrous salts, the existence of another possibility based on the development of a heterogeneous reaction through an electrochemical path is suggested.
The authors' opinions on the physical meaning of monitoring the corrosion state of aluminium brass tubes and on its technological validity and usefulness when dealing with problems associated with the operation of the steam condenser of a thermal power plant are then discussed for examining the true content of the information obtained from this technique.
Finally, a detailed description is given of the monitoring system installed on the condensers of Units 3 and 4 at the Fusina thermal power station. At present the system consists of three-electrode probes of Electricity Board - Thermal and Nuclear Research Center (ENEL-CRTN) design, an Atel computerized corrosion rate meter and a Hewlett Packard (HP) instrument controller. The two programs, necessary for data acquisition and information retrieval, respectively, were developed by our laboratory, and their use requires a specific Hewlett-Packard operating system.
From a technological standpoint, the results obtained in three years period were satisfactory in that they helped the chemist of the thermal power station in such activities as run the ferrous chloride dosing system, define the length of the continuous sea water treatment, check the integrity of the protective film, detect the presence of extraneous bodies, and conduct the discontinuous conditioning operation correctly.
