API 579-1/ASME FFS-1 Part 9 provides assessment procedures for evaluating crack-like flaws in components to determine if it is fit for continued service. Although residual stress distribution is required as an input to perform a fatigue life assessment, no procedure or guideline is available for evaluating this crack driving force resulting from thermal shocks.
Through a systematic analysis, a conservative residual stress distribution can be obtained for pressure vessels subject to thermal shocks. For the two thick-walled vessels considered, the maximum residual stress occurs when the vessel is half filled with water. The conservative residual stress provides the needed input when using API 579-1/ASME FFS-1 for evaluating crack-like flaws in components. Dependence of the residual stress on film coefficient, temperature difference between water and metal surface, and water level inside the vessel is also presented so that refinement can be made on life assessment when additional field data becomes available.