This is kinda hard to explain without a drawing but I'll try. Imagine an L-shaped structure with a weld going down the vertical part connecting the L to a vertical pipe on the left side of the L. The curvature of the pipe is insignificant. Then on the L's right end is a vertical downward load. I find that I have a [tex]\tau_\|[/tex]. This I can see, since the weld is being "streched" in a paralell direction, but my book also tells me that [tex]\sigma_\bot = \tau_\bot[/tex] is also part of the problem, and I am not able to see why this is...can someone please help me?