INTRODUCTION

In cooling water systems, corrosion and fouling problems are not new, but continuing trends in environmental legislation are leading to ever-greater degrees of evaporation and consequently to very high residual concentrations of various species. Thus, even if the make-up waters used are initially clean and noncorrosive, because of this concentration effect, they become corrosive and their tendency to induce fouling increases.

Faced with this situation, those responsible for cooling water treatment tend to respond on a case-by-case basis, leading to a wide variety of treatments. However, the cooling water system operator, who pays for these treatments, must be able to assess their validity. This publication endeavors to describe in clearly understandable terms what happens in the cooling water as it becomes more concentrated, and what occurs during the different treatments to which the cooling water is subjected. It is then possible to consider the interaction between a particular cooling water and the materials with which it is in contact.

It is emphasized that the design, construction materials, and the mode of operation of a plant can often be much more important than the composition of the make-up water to its cooling water system.

This publication provides the theoretical and practical background necessary to understand what goes on within cooling water systems, and how to evaluate corrosion and fouling. Readers will then be in a position to discuss problems and solutions with their cooling water treatment vendors, and the aim of this publication will have been achieved.

Appendix A incorporates four tables listing important criteria for selecting and applying water treatment chemicals and controls for open recirculating cooling water systems based on available technology at the time of publication.