Eileen Chant, Ph.D., P.E.; J. Robert Sims; Charles Becht V
Boiler tube failures are the leading cause of fossil plant downtime worldwide. Advances in life assessment modeling tools could improve fossil plant reliability while minimizing maintenance costs by improving timing of inspection, repair and replacement activities. Becht Engineering was commissioned by the Electric Power Research Institute to better understand the remaining life predictions produced by the EPRI software programs Remaining Life Simulations and Monitoring (RLSM) and Boiler Life Evaluation and Simulation Software (BLESS), and compare those methods and results with the API 579-1/ASME FFS-1, 2007 Edition model. The types of damage considered in the study include creep rupture, creep-fatigue and creep crack growth.
RLSM and BLESS have many features in common with the modeling approaches in API 579-1/ASME FFS-1, the main exception being the absence of the Omega Material model in the EPRI software programs. Because of this, one emphasis of the project was to present the Omega model and contrast it with the legacy approach, the Larson Miller Parameter (LMP) model.
Some discrepancies between LMP and Omega models in API 579-1/ASME FFS-1 were discovered and described in our findings.For the BLESS comparison, data sources referenced by BLESS were reviewed in performing fatigue crack growth and creep crack growth and recreated these calculations. Comparisons with API 579-1/ASME FFS-1 predictions were made and the reasons for any noted discrepancies described.
Finally, Becht Engineering has made a number of recommendations regarding future enhancements of the EPRI programs.