Analysis of Fatigue–Creep Crack Growth in the Superheater Header of a Power Plant Boilers and Estimation of Its Remaining Lifetime

摘要

AbstractAs superheater header is exposed to high pressure and temperature in power plant boilers, it is one of the most sensitive parts in a power plant.Cracks may form where tubes and main steam outlet (nozzle) are connected to reservoir. This article examines a quarter-circle crack at the corner of a nozzle junction and its propagation steps under the influence of simultaneous interaction of creep and fatigue. Header loading in each cycle includes transient steps (increase and decrease in temperature and pressure) at the beginning and at the end of a cycle and intermediate steady state (fixed pressure and temperature) during operation. For crack growth calculations, stress distribution in a track-free part was calculated. Fatigue–creep crack growth was achieved using crack growth rules and the remaining lifetime was obtained. Research result shows that creep phenomenon is responsible for maximum crack growth.]]>