Ultrasonic thickness measurement of power station boiler tubes using electromagnetic acoustic transducers

Ageing coal-fired power station boilers require a considerable amount of life management because of environmental conditions, whether due to fuel combustion, heat, water chemistry and so on. This life management includes regular non-destructive testing surveys, particularly monitoring of the wall thickness of boiler tubes by ultrasonics in susceptible or targeted locations. In turn, this requires a significant amount of expenditure on surface preparation, often considerably more than the cost of inspection. With this in mind, National Power plc has for some time been interested in exploiting non-contact NDT Techniques for wall thickness monitoring, thus minimising these costs. This paper describes such an application using Electromagnetic Acoustic Transducers (EMATs) that has been developed by Warwick University within a DTI-funded Teaching Company Scheme