The actual life of a component may be more than the design life if the properties assumed were lower or the factor of safety was higher or if the plant was operated conservatively or the oxidation effects were over estimated. Hence a residual life assessment may be quite appropriate.
Two methods are available for Residual Life Assessment Plant components, one using data analysis based on operational history and the other based on periodic examination of critical components. The latter method is widely adopted in the industry as it is more reliable.
Standard techniques utilized at AEIS for for RLA studies include: Visual examination, Dimensional measurement, Ultrasonic thickness gauging, Penetrant testing, Magnetic particle inspection using wet fluorescent method and Eddy current test.
Specialized techniques utilized are: In-situ replica technique to study the material degradation and the presence of micro cracks, Fibreoptics, ultrasonic testing using high frequency pulser and transducer for measurement of oxide scale, ultrasonic attenuation measurement to detect hydrogen damage, boresonic inspection using multi probes with special attachment to detect cracking in rotor bores and special eddy current technique to detect turbine blade root cracks.
