Originally Posted By: RyanF
Not sure it makes any difference to the discussion of what loads to shoot but, hoop stresses are in fact highest on the inside face. You cant figure it out from the Pr/t equation (a simplification) You need a different method.

Hoop stress = ri^2 x P/(ro^2-ri^2)x(1 +(Ro^2/r^2))

ri = inside radius, ro = outside radius, r=spot in question (r=ri if you want the max stress)

I've always believed it was higher on the O.D.in part due to the bending moment of the wall. I also understood that a thick wall cylinder had different force ratios going on than thin wall cylinders. Is that what you refer to?