The internal corrosion of high pressure fossil fired boilers can lead to rapid metal wastage if the conditions required for the formation of protective indigenous magnetite are not maintained. Detection and recognition of conditions leading to accelerated corrosion are essential in reducing short and long term metal loss. Since many boilers operate for at least a year between inspections, indirect methods of corrosion monitoring must be used. Hydrogen results from the reaction between steel and water or steam. Measurements at suitable points of the water-steam circuit can supply qualitative and sometimes even quantitative statements on corrosion processes. Examples of these are excessive scale formation or destruction by chemical attack or thermal influences. Thus, it is important that hydrogen measurements are used frequently to check the operating behaviour of steam generating plants and to optimize their operation. In the past, it was felt that the results of hydrogen measurements would be no more than a summary indication of many processes which may take place within a system with a large surface and which could not be localized or defined. This is certainly true if the hydrogen measurement is considered only on its own. However, in combination with other analytical and operational parameters, it supplies useful information essential for tracing deficiencies in the mode of operation which could not have been found with the usual analytical methods alone.
