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The current paper presents the ongoing development of a combination of two methods for monitoring creep strain in mechanical components of electrical power generation plants. This is to obtain, during plant shut-down maintenance periods, needed data to assess the remaining life of installed steam pipes and other components. Related to this research, but not reported on in the current paper, is the development of monitoring for detection of the onset of fatigue and other failure processes in wind turbine generator blades. The auto-reference creep management and control (ARCMAC) system uses precision optics and a charge-coupled device (CCD) camera for uniaxial and biaxial strain measurement. Digital image correlation (DIC) is employed to obtain strain distribution data about the ARCMAC point-to-point monitored sites. These and other systems are being developed to obtain a more comprehensive range of life assessment data. This is mostly for assessing longevity of steam pipes and other components in power stations that are subject to demanding and hostile operational environments. These permanently installed monitoring systems need to be rugged to withstand the demanding heat and mechanical forces to which they are subjected and of a compact design so they can be sited in difficult-to-access locations. This is one of the advantages of the combined ARCMAC and DIC system that is further being developed. These systems are essential for cost-effective management of power plant operation and maintenance and for achieving reliable continuity of service.

Sensors for monitoring creep strain in high-pressure steam pipes and other power plant components are subjected to very demanding environmental and operational conditions. It is important that the sensors are of a rugged design and that measurement can be made that only relates to creep movements in power plant components. The E.ON UK auto-reference creep management and control (ARCMAC) optical strain gauges have been designed to have this capability. These optical strain gauges are installed across sections of welded steam pipe and other plant components in locations that provide the best monitoring points to reveal the early onset of failure processes. Reported in this paper are recent developments to improve optical creep strain measurement to achieve a 65 microstrain accuracy level with an error of less than 10%. Also reported are trials of combining optical strain gauges with digital image correlation (DIC) to obtain detailed information of the creep strain distribution around the gauges. The DIC data for known defect geometries have been validated with finite element analysis.