To ensure against elastic buckling an approximate formula from Roark (see
Reference 24, Formulas for Stress and Strain, 1965) is employed
ts
[sigma]cr = 0.3 E ----
rs
where
[sigma]cr = critical compressive stress, psi
E = modulus of elasticity, psi
rs = mean radius of cylinder, inches
[sigma]cr = 0.3(29 x 106) (0.25)/60.125
[sigma]cr = 36,175 psi >> 2,000 psi
Thus the support skirt will not buckle under the dead weight load.
(6) Penetrations & Openings, Reinforcement. Paragraph AD-510 of
Article D-5 sets the diameter limits on penetrations and openings that
require no reinforcement. This limit is
This means that penetrations for the 4.0 inch inlet and outlet pipes as well
as the penetration for the 40.0 inch entranceway will require additional
material to act as reinforcement. Penetrations with a diameter equal to or
less than 2.69 inches require no reinforcement so long as the conditions
stipulated in AD-510(b) and (c) are also met. These conditions deal with
spacing limitations between adjacent unreinforced openings or proximity of
unreinforced openings to the edge of outer holes and/or local stress areas.
It must be emphasized that this limitation is based solely on pressure
loading. In the words of paragraph AD-500
"... These rules do not include design requirements for piping
loads that may be imposed on the nozzle and/or shell portion and
that may be added to the pressure loadings. Such additional
loadings should be carefully considered by the designer."
Paragraph AD-520 "Required Reinforcement for Openings in Shells and Formed
Heads." This delineates the area replacement concept inherent in the
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