Water and Energy Abstracts
Year : 2004, Volume : 14, Issue : 1
First page : ( 39) Last page : ( 40)
Print ISSN : 0021-1672.

103. In-situ Estimation of Fatigue Life of Power Plant Components through Measurement of Surface Residual Stress

Prasad C.R., Jayaraman G.

(BHEL Journal, December 2003, pp. 42).

Abstract

Thermal power plant components subjected to fatigue damage are conventionally designed to operate for a period of 30 years. However, the safety factors used during design can permit some of the major components to be used well beyond their design lives. On the other hand, if the equipment is used beyond its rated capacity, the service life could be much shorter than the design life. Any evaluation of life is meaningful only if it is non-destructive. The fact that fatigue is a surface-dependent phenomenon and that a build-up of tensile residual stress is a must for fatigue crack initiation, has been taken advantage of to develop a non-destructive method of fatigue damage evaluation prior to crack initiation. X-ray diffraction and Barkhausen Noise techniques were used to develop methods for evaluating low-cycle fatigue damages and high-cycle fatigue damages in steam turbine components. These techniques, after being developed and tested in the laboratory, have been used at a few sites for determining the fatigue life of service-exposed components.

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Keywords

Thermal power plant, Low-cycle fatigue, High-cycle fatigue, Residual stress, Damage evaluation, Life assessment.

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