Control of Corrosion in Cooling Waters (EFC 40) PDF

Introduction

In cooling water circuits, corrosion and scaling 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 waters used are initially clean and non-corrosive, because of this concentration effect, they become corrosive and their tendency to induce scaling and biofouling increases.

Faced with this situation, those responsible for water treatment tend to respond on a case-by-case basis, leading to a wide variety of treatments. However, the circuit operator, who pays for these treatments, must be able to assess their validity. This is the purpose of the present guide, which endeavours to describe in clearly understandable terms what happens in the water as it becomes more concentrated, and what occurs during the different treatments to which it is subjected. It is then possible to consider the interaction between a particular water and the materials with which it is in contact. This is the problem of I corrosivity', which must be clearly distinguished from that of 'aggressivity' (with respect to marble).

It is emphasised that the design, the conditions of construction and the mode of operation of a plant can often be much more important than the composition of the circuit feed water.

Readers will discover that all the theoretical background necessary to understand what goes on within cooling circuits has given rise to methods for evaluating both corrosion and scaling. They will then be in a position to enter effectively into dialogue with their water treatment providers, and the aim of the present guide will have been achieved.

Edited by: J.D. Harston, F. Ropital