IJE TRANSACTIONS B: Applications Vol. 26, No. 5, (May 2013) 543-552 International Journal of Engineering Journal Homepage: www.ije.ir Failure Probability and Remaining Life Assessment of Reheater Tubes E. Poursaeidi *, A. Moharrami, M. Amini Department of Mechanical Engineering, University of Zanjan, P. O. Box 45371-38791, Zanjan, Iran PAPER INFO Paper history: Received 19 December 2012 Accepted in revised form 24 January 2013 Keywords: Structural Reliability Analysis Failure Probability Remaining Life Assessment Reheater Tubes RALA software ABSTRACT In this study, a real and significant industrial problem in a steam power plant was investigated. Reheater tubes in boilers are under 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 by 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 carried out 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. doi: 10.5829/idosi.ije.2013.26.05b.11 Nomenclatures C Material constant x * Design point in the physical space f x(x) Joint probability density function of basic random variables x * i a Sensitivity factor g(x) Failure function or limit state function or performance function b Reliability index j k Main curvatures of the quadratic hyper-surface at the design point ax s Axial stress K Wall thinning rate H s Hoop stress M Total independent samples r s Radial stress * M Number of samples among them satisfying g(x) 0 £ ref s Reference stress n Stress sensitivity coefficient U s Material ultimate strength N Number of simulations y s Material yield stress P Internal pressure * s Von mises stress F P Failure probability F Cumulative standard normal distribution function L P Current load X Random variables in physical space * Corresponding Author Email: epsaeidi@znu.ac.ir (E. Poursaeidi)