Crack modelling in power plant components

Abstract

Much of the process plant designed in the early 1970s, in response to increased demandfor power, is now 'ageing' and necessitates an on-going fitness for service' assessment. This is necessary to satisfy licensing authorities requirements for continuous operations. Fitness for service assessment involves many issues including evaluation of structural flaws, material degradation, damage due to creep, fatigue and plasticity and the overall effect on the residual life of components. Codes of practice such as API 579, BS 7910 and R6 give detailed assessment procedures and may involve very detailed and time consuming finite element analyses. The authors have developed an FEA tool, Zencrack, to accurately evaluate single or multiple cracks in any structure (e.g. pressure vessels, piping, etc.). Further, 3D non planar crack growth under general fatigue or time dependent loading is possible. The software can help to increase efficiencyin performing sensitivity studies, thus allowing more accurateassessment of the residual life of the plant than would otherwise be possible in a given timeframe.