An on-line fouling monitor was employed to obtain over five million hours of data on
fouling in recirculating cooling water heat exchangers. From these data a model was developed
to predict cooling water heat exchanger fouling performance irrespective of water chemistry. The
predictive index was subsequently applied to actual operating exchangers with excellent correlation. A Case study is presented demonstrating verification of the predictive index.

Key words: Wilson Plot; fouling factor; Hydrothermal Stress Coefficient; residence time; cost of ownership