The economics of repeated tube thickness surveys

The use of tube thickness surveys in boilers is an example of a commonly applied condition monitoring (CM) technique for maintenance and it leads to condition-based maintenance (CBM) of the boiler tubes. There are, however, limits to the economics of this type of strategy which are frequently overlooked in discussion of CBM strategies. This paper considers several models of maintenance strategies. Conditions in which breakdown maintenance (BM), routine total replacement (routine maintenance, RM) and condition-based replacement (which for simplicity is referred to as CM) are considered. Some general rules about the economical range of each strategy are developed. The case study examines the use of ultrasonic testing of boiler tubes in power stations in some detail