Stiffeners internal ring

An internal stiffening ring is the most desirable from a strength standpoint because the maximum stress in the shell is compressive, which is reduced by internal pressure. An internal ring may not be practical from a process or corrosion standpoint, however. 

Fl = longitudinal force due to wind, seismic, expansion, contraction, etc., lb Ft = transverse force, wind or seismic, lb CTx = longitudinal stress, internal pressure, psi = circumferential stress, internal pressure, psi CT,. = longitudinal stress, external pressure, psi CTs = circumferential stress in stiffening ring, psi <7h = latitudinal stress in head due to internal pressure, psi... 

Whenever possible, shipping saddles should be located adjacent to some major stiffening element. Some common stiffening elements include stiffening rings, heads (both internal and external), or cones. If necessary, temporaiy internal spiders can be used and removed after shipment is complete. 

Kj = internal tension/compression coefficient in circular ring due to radial load Ls = length of skirt/base stiffener/strut, in. 

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