Remaining Life Assessment Of Steam Turbine And Hot Gas Expander Components.

LecturePg. 77-92In today’s marketplace, a large percentage of oil refinery, petrochemical, and power generation plants throughout the world have been trying to reduce their operation cost by extending the service life of their critical machines, such as steam turbines and hot gas expanders, beyond the design life criteria. The key ingredient in plant life extension is remaining life assessment technology. This paper will outline the remaining life assessment procedures, and review the various damage mechanisms such as creep, fatigue, creep-fatigue, and various embrittlement mechanisms that can occur in these machines. Also highlighted will be the various testing methods for determining remaining life or life extension of components such as high precision stress relaxation (STR) test, which determines creep strength, and constant displacement rate (CDR) test, which evaluates fracture resistance. Other test such as replication/microstructure analysis and toughness test will also b reviewed for calculating the remaining life or life extension of the components. Use of the latest computer software will also be highlighted showing how creep-life, fatigue-life, and creep/fatigue-life calculations can be performed. Also shown will be actual life extension examples of steam turbines and hot gas expander components performed in the field