Stress Intensification Factor for Large Diameter Welding Tee Connections

Stress Intensification Factors (SIFs) are factors relating to fatigue characteristics of piping components. SIF is fatigue correlation which compares fatigue life of a typical piping component such as a tee and elbow to the reference fatigue life, that is girth butt welds in straight pipe subjected to bending moments. In order to calculate localized stress of such piping component, above mentioned figured out SIF shall be multiplied by nominal stress. ASME B31 contains several formulas for stress intensification factors considering limitation that those formulas are valid only for D/T≤100 (diameter to thickness). Extending the valid range mentioned in ASME B31 this paper is dedicated to SIF calculation for D/T≤100 and also for D/T>100 by utilizing Finite Element Analyzing (FEA) for welding tee. The computed SIF for D/T>100 welding tee can now be placed to typical pipe stressing program which analyzes piping system using beam elements. In addition, this paper investigates the effect of R_x (the magnitude of corner radius of shoulder at branch) on SIF of Welding Tee Connections.