bolted tanks

huangyhg

bolted tanks
hi all,
the pe i work for is out of town and our mech guys "don't do tanks." so here it is - working on a 24' diameter pressurized tank.  the tank consists of 3 rings with an average width of 13'. the shell thickness is 3/16" a-36 steel.  the tank is bolted construction with a top and bottom flange that is welded onto the panels (3/8" plate 6" wide). the sides are overlaped and reinforced with 3/8" plate 6" wide. the bolts are a-325 5/8"diameter.  the operating pressure of the tank is about 1psi (20"wc)with an explosion relief vents that engage at 3.25psi. ok, here is my question: i calculated my tangential and axial stresses (2.496ksi and 1.248ksi respectively)but i am a little confused as to how this data translates to the bolt spacing along the edges. my preliminary calcs give me 5 1/4" o.c. at the overlap and 4 3/4" o.c. at the flanges. am i on the right track?  
have you gotten the seismic overturning moment?