Failure Probability and Remaining Life Assessment of Reheater Tubes

In this study, a real and significant industrial problem in a steam power plant was investigated. Reheater tubes in boilers are under the creep and the fireside corrosion mechanism that cause some of them to fail. Since the estimation of probability of failure (PoF) and remaining life (RL) is expensive and time consuming in the deterministic methods, in this work they were evaluated using structural reliability analysis and distribution analysis based on in-site tests and selecting an appropriate limit state function (LSF).The criterion used for this purpose is based on the creep lifetime model and uncertainties. Sensitivity analysis was also studied in this research. The considered relationship among three affecting parameters on boiler tube failure including time, creep and fireside corrosion leads to evaluating RL besides PoF as well as obtaining PoF and RL simultaneously by selecting an appropriate time-based LSF. Most accurate results were achieved based on obtained PoF and RL values which cause to provide more reliable results for economic planning of future inspection periods. This leads to significant cost savings and operational safety improvements. A new software package, named RALA was developed via programming in Matlab. The obtained results are in good agreement with all data gained from the practical experiments in the power plant based on the previous studies.