A Comparison of Methods Used to Evaluate Field Measured Transient Thermal Data and the Impact on the Design and Fatigue Life

摘要

Many vessels experience significant thermal cycling during operation, which can have a severe effect on the fatigue life of the vessel. In a thermal analysis it is critical to determine the correct boundary conditions to achieve the proper results and behavior. Improperly applied heat input and losses can have a dramatic effect on the overall design and fatigue life of the equipment. On occasion classical equations are not available to calculate thermal boundary conditions. When direct correlations are not available it is possible to use field measured thermocouple data to develop the heat input. This paper compares two different methods of applying transient thermal boundary conditions using field measured data and discusses the impact on the fatigue life. Examples are provided to show how the assumptions on the boundary conditions can directly affect the results. The examples provided in this paper use Finite Element Analysis (FEA) to quantify the results due to the different methods.