Flexibility Factors for Branch Pipe Connections Subjected to In-Plane and Out-of-Plane Moments

Stress intensity factor and flexibility factor are important analysis parameters for branch pipe connections subjected to in-plane and out-of-plane moments. The calculation of stress intensity factors for a large range of unreinforced fabricated tees (⁠$0.333⩽d∕D⩽1$⁠, $20⩽D∕T⩽250$⁠, $d∕D⩽t∕T⩽3$⁠) was performed by Widera and Wei [WRC Bulletin 497 2004] and empirical formulas were provided based upon a parametric finite element analysis employing four-node shell elements. The purpose of this paper is to extend the previous effort by Widera and Wei and calculate the in-plane and out-of-plane flexibility factors for the same range of geometric parameters. Similarly, empirical formulas for the determination of these flexibility factors are proposed. The results show that the lengths of the branch and run pipes as well as the geometric parameters (⁠$d∕D$⁠, $D∕T$ and $t∕T$⁠) have an effect on the calculation of flexibility factors.