Reliability Prediction for Reforming Tube by Probabilistic Assessment of Outer Diameter Distribution

摘要

In using the annual data of outer diameters in reformer tube, a statistical treatment was accomplished in order to predict expansion rate and reliability of the tube by probabilistic assessment The distribution of outer diameters detected by ultrasonic test was identified as the 3-parameter Lognormal distribution deviated from the normal distribution by severe increasing of dispersion and its fluctuation as annually using the tubes. In the assumption of critical value (CV) determination for the outer diameter the probabilistic assessment was proceeded into deriving the failure probability from the statistical information. Finally, the safety index was also derived from the failure probability, making the failure estimation available for each annual using of the reformer tubes.