The stress state for various pipe tees under combined thermal and mechanical loading is analyzed using a Finite Element Analysis (FEA). The stress states produced for loaded branch tees of different aspect ratio geometries are found by FEA method. The stress intensification factor is calculated and compared to the Code values and experimental data.
The state of stress in a piping system is produced by the combined loading of in and out of plane forces and moments due to the applied loading, dead weight and constrained thermal expansion or contraction. The highest states of stress in a piping system are usually found at fittings and components where there is a major change in the geometry. This localized peak stress is described by a Stress Intensity Factor, SIF which is defined as the peak stress in the body to a nominal stress. Determination of the SIF is not easily calculated due to the complexity of the piping network. As the SIF may not be readily determined analytically for branch tees under combined loading, the use of a computational method such as the finite element method is beneficial. Early work in this area using finite element analysis had been limited by the large computational requirement for three dimensional solid modeling. As the capabilities of FEA software and the capacities of computers have increased, the ability to perform large, tightly meshed finite element analysis has greatly improved with good results for complex loading. Early analytical work was limited, therefore experimental research on piping components was performed to determine an empirical means of characterizing the stress for application purposes. Testing was performed on a 4x4x4 standard tee at ambient temperature to develop Stress Intensification and
