A Review of Methods to Estimate Creep Damage in Low-Alloy Steel Power Station Steam Pipes

摘要

For large complex structures, such as power stations, refineries and other processing plants, cost-effective operation is essential. With power stations, failures of components without prior warning can have serious consequences for personnel on-site and be extremely expensive in terms of both losses in generation revenue and repair costs. The ability to monitor and assess the evolution of damage is critical to maximise plant availability and to minimise the risk of failures that pose a threat to personnel safety. This paper relates to the methods used to estimate creep damage in service-aged low-alloy steel steam piping. Welds and the extrados of bends in steam pipes are a particular problem with regard to measuring for the onset and progression of creep failure. Existing techniques will be discussed with respect to traditional site-based, sample extraction and assessment. Emerging strain-monitoring techniques will also be described and evaluated that include point-to-point measurement and two-dimensional mapping of creep strain across the weld zone and other creep-susceptible components of power station steam piping.