Fatigue

On header stubs and the combined parts of furnace waterwall tubes, high temperature low cycle thermal fatigue may occur due to cycle of thermal stress at start-up and shut-down. In addition, inside of the economizer or the waterwall tubes, corrosion fatigue combined with environmental corrosive action occurs. Such fatigue damage is influenced by the size of cyclic stress, the number of cycle, and atmospheric corrosiveness.

Fatigue Damage Detection Method

• Regarding high temperature low cycle fatigue, micro cracks of a maximum of 1 mm is detected before occurrence of macro cracks to diagnose the fatigue damage rate.

• Regarding corrosion fatigue of the inner surface of the tubes, cracks are detected, measured and diagnosed in a dedicated ultrasonic method.

Crack Propagation and Remaining Life Diagnosis Method

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