Corrosion Monitoring for Chemical Plant

The successful exploitation of many chemical processes is influenced to a marked extent by the availability of suitable constructional materials. Sometimes it is possible to reduce the danger of corrosion by operating at below the desired temperature, acid concentration or pressure, while in other cases an unnecessarily expensive material has to be chosen for the sake of safety. Generally it is advisable to work at temperatures, etc., considerably below those which would normally cause corrosion because, if the plant is not monitored from a corrosion point of view, no risk of even a temporary breakdown can be taken. In other words, it is difficult to make the best use of the available materials without some sort of instrumentation which can give warning of impending trouble. Coupled with such instrumentation there must be a knowledge of possible emergency measures which can be taken to ‘help’ the plant over a difficult period (e.g. when an unusually corrosive batch of material happens to be passing through). The possible techniques for these purposes must depend on the system under consideration, but it seems that the monitoring instrument could very often consist of a simple valve voltmeter and a multi‐point recorder or indicator. Potential measurements are frequently used in the laboratory to follow corrosion reactions on specimens, and in the present paper it is suggested that this well‐tried laboratory technique could well be used in practice more often than it is.