Remaining Creep Life Assessment Techniques Based on Creep Cavitation Modeling

The boiler and its components are built with assumed nominal design and reasonable life of operation about two to three decades (one or two hundred thousand hours). These units are generally replaced or life is extended at the end of this period. Under normal operating conditions, after the initial period of teething troubles, the reliability of these units remains fairly constant up to about two decades of normal operation. The failure rate then increases as a result of their time-dependent material damage. Further running of these units may become uneconomical and dangerous in some cases. In the following article, step-by-step methodology to quantify creep cavitation based on statistical probability analysis and continuum damage mechanics has been described. The concepts of creep cavity nucleation have also been discussed with a special emphasis on the need for development of a model based on creep cavity growth kinetics.