In-Service Structural Integrity Assessment Using Computerized Materials Models and Data

Abstract

Many large-scale engineering structures, such as steam generation plant and petro-chemical plant, operate under conditions in which the key materials properties diminish with time. Detailed understanding of this degradation is essential for structural integrity assessments, and computerization of the collection and analysis of these materials data can realise significant savings in the cost of structural integrity assessment. The authors give examples of the various methods used to obtain data and to extrapolate rates of material degradation in order to predict failure. It is shown that, from the design stage, certain assumptions, some necessary, some dubious, are incorporated into standard materials property data. Such simplification may be necessary during design but represents a challenge for in-service assessment, when a statistical or stochastic approach is required. In addition, it is noted that hardly any publicly-available computerized materials databases contain the properties of alloys following service exposure. A natural extension of computerized assessment of data is to monitor the consumption of life during service. A continuous monitoring system is described which will take advantage of material degradation models to provide real-time analysis of plant integrity.