The water and steam side surfaces of a high pressure fossil fuel boiler are subject to a variety of potential corrosion problems. Construction materials include copper alloys, carbon steels, ferritic alloys, and austenitic stainless steels. Assessing the degree of corrosion of components is important to allow planning for maintenance during scheduled outages and to avoid unscheduled downtime. Corrosion control programs recommended by Combustion Engineering, Inc. (CE) include two areas of corrosion monitoring. First, on-line monitoring of the water and steam side environment is used to evaluate the duration and degree of exposure to corrodents, and to provide feedback information to assist in minimizing corrosion. In addition, both nondestructive testing and destructive testing during unit outages is used to assess corrosion damage. Typical operational corrosion problems in a high pressure (1241 kPa [ > 1800 psi]) fossil fuel utility boiler are detailed and recommended corrective measures are presented.