| Summary: | Power generation companies are under a great deal of Government and other pressure to achieve and maintain their plants to a high efficiency standard with minimum release of CO2 into the atmosphere. Achieving and maintaining the required high level of operational integrity of large complex generating plants is a demanding task. One key requirement is to have data on the functional integrity of all major components of a power station plant This is to provide for removal from the plant of time expired components. This is particularly important for components that can only be replaced by shutting down the plant and having to do this very often is a problem. This dissertation relates to the life monitqfing of steam pipes and other components that are .subject to· demanding high temperatures and stresses. Life monitoring· of these components requires instrumentation that can withstand for long periods these very hostile conditions on and about the steam pipes. Creep monitoring is one key requirement and sensors need to be able to detect very small growth movements of the material and have the ability not to be affected by the hostile environment in which they are located. Ideally, for creep monitoring in steam pipe material, required is a precise point-to-point measurement in two or more directions together with strain mapping of the region in and about the point-ta-point sensors. E.ONUK is supporting this research to improve their life-monitoring systems and in so doing have regard for the trend to use even high temperature steam pipes in the next generation of power stations. To illustrate the above in this thesis, the development of a Strain Monitoring System is presented: the Auto Reference Creep Management And Control System (ARCMAC). This is a strain sensor system which is developed at Imperial College in collaboration with E.ON. UK. From design studies and operational experience of pipe degradation rates and failures, useful information is available as to parts of the pipe system that need to be monitored to obtain reliable data on the remaining life of the pipes. Also known is that a good and feasible monitoring method to reveal the onset of failure processes is the measurement of the increases in micra-strain generated in the outer skin of the pipe material. For these measurements, the ARCMAC system has been developed. The ARCMAC measurement system utilizes precision optics to capture successive images of a 'target' strain gauge and digital image processing is used to obtain estimates of creep s~in accumulated over the plant-operating period. The Digital Image Correlation (DIC) technique is also presented as an alternative measurement technique. In this technique a series of digital images of a surface is uSed under various levels of load, upon which a paint pattern has been applied. The first such pattern to be used in the UK on a power station was applied in Ratcliffe power station as part of this study. The DIC technique will be used in conjunction with ARCMAC gauges to evaluate any unusual strain distribution surrounding the gauge area in an effort to create a unified Strain Monitoring System combining both techniques. Full field case studies are examined and presented showing encouraging initial results.
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