[PSUBS-MAILIST] Pressure Vessels

[Tim Curtis <navark@yahoo.com>]

Phil,

What numbers did you use for yield strength, modulus
of elasticity, and Poisson's Ratio?

 -Tim



Hi, Bill:
Just as a guide . . . for your mild steel 15' X 46" X
.27 hull - the calculated depth before the hull  turns
into a halibut from assymetric buckling is:
Unstiffened: 100 feet
Single stiffener: ( unsupported section = 90"): 200
feet Three stiffeners, ( unsupported section= 45") 400
 feet Cut these approximate values in half to get the
safe working depth . . with no stiffeners you're
looking at 50 feet and so on.If you can't afford the
space inside, put them externally - but remember to
cap the perpendicular with a flat band so that you
have a 'T' section. If you want to avoid either a
doubler ( the traditional fix) under your 'conning
tower' or a series of gussets, you can put a wide
horseshoe - shaped stiffener right in the 'V' - so the
stiffener is at 1:30 if the side of the 'conning
tower' is 12:00 and the flat of the hull is 3:00 ( 
assuming that your trunk ends in a point on each side
of the hull.) By the way, a 46" dia. hull by 15' is
pretty big.  A more usual length is 10 - 12' What's
goin' in there besides you?
Phil Nuytten


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