Evaluation of creep damage in some major components of power generator

Life extension of installed machinery and equipment has become a matter of strategic importance with significant economic implications especially in power plants. The paper presents a complex of methods aimed at assessment of the residual service lives of major components of power plant machinery (steam turbines, steam line systems) under creep conditions. The methods are based on a mathematical model of properties of creep-resistant steels based on the dislocation mechanism for which stochastic behavior of material in the course of the strain mechanism has been assumed. A method is proposed to evaluate the equivalent service load in actual service conditions by means of a computerized data acquisition. The method is applied to monitor creep damage of steam turbine pipelines. Creep damage of turbine rotors and casings and plastic deformation in their critical points were estimated numerically. The actual time span of reliable operation of a component is assessed by these method and compared with results obtained by diagnostic methods prepared in cooperation with manufactures of power generating machinery. (author)