NDE Inspections and Lifetime Assessment of Turbine Equipment

The growing demand for power is putting tremendous stress on existing power plants for generating electricity. The plants are being operated for longer periods of time under heavy load conditions. Reliability of key components of the power plant such as steam or gas turbines and generators is of prime importance. Many utilities are interested in extending the life of turbine-generator components to reduce costs while maintaining safe operating conditions. Turbine rotors being operated past their anticipated design life objectives are of special concern. Life assessment studies must have metallurgical and nondestructive testing evaluations to help assess the suitability, if any, for the continued operation of the component. Conventional nondestructive testing such as visual and magnetic particle inspection can be used for surface assessment while ultrasonic testing as well as phased array ultrasonic testing can be used for internal assessments. Phased array ultrasonic inspection of critical areas such as blade attachments and blade roots allows the inspection to be performed without removal of blades. Information obtained from both NDE and metallurgical assessments is combined with engineering evaluations to perform an effective life assessment of components. Using unit operational information and NDE tools, combined with metallurgical data gathered on service components, provides a comprehensive assessment allowing users to make informed judgments regarding potential further safe and reliable operation of critical power plant components.