Abstract: According to the complicated conditions ans and specific environment of large Francle turbine, a comprehensive design method for avolding fatigue failure is proposed in the paper. The method made use of the theories of random fatigue and corrosion fatigue is based on a large number of statistical data and fatigue experiments. The paper includes the determination of design load spectrum, fatigue charactristion of the materials in corrosive environment, various factors affecting fatigue strength and ways of calculating service life and safety factor etc. The results of this study would supersede static design method of the turbines and can more efficiently evaluate the safety of the turbine against fatigue failure in design or in service.

Key words: Fatigue strength, Francis turbine, Safety factor, Service life