Ring Stiffeners

["richard hess" <rohess@hotmail.com>]

Gene,

The "T" stiffener is a piece of steel that has a "T" shaped cross 
section, The "T" might measure 2.5" X 3" in cross section.  A length of 
this shape of steel is rolled into a ring, with either the leg of the 
"T" pointing in toward the hull or out. The ring stiffener should be 
made of the same kind of steel as the hull cylinder. The ring is then 
welded on the outside of the hull at positions located according to a 
pressure vessel formula. Typically more ring stiffeners are placed 
around any large opening or "nozzle" as it is called in pressure vessel 
lingo. Being located on the outside of the hull the ring stiffeners do 
not take up space inside, but they do add drag unless they are covered 
with some sort of a fairing, or ballast tanks.  The Perry PC-14 class of 
manned submersible is an example of a manned submersible built with this 
type of an external ring stiffener.

Richard Hess

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