Bending stress in horizontal press. ves. saddle base plate

dannyo · Sep 26, 2001

I am looking for a correct formula for the bending stress in the saddle base plate of a horizontal pressure vessel. The current formula I have has incorrect units.

fb = [(6*M)/(tb^2)] is the formula I'm using (units of lb/in instead is lb/in^2), where fb = bending stress, M = bending moment, tb = base plate thickness.

I have limited access to references so I would appreciate any formula or online reference site anyone could provide.

Also, if this is the correct formula could someone explain to me why the units are not in psi.

prex · Sep 27, 2001

My first remark is that your baseplate for sure does not work alone, and should be stiffened by a web plate to which a cylindrically shaped plate is superposed (and onto the latter one is laid the vessel).
Your formula gives the stress in a plate alone, without any ribs, so it is not the correct one. However I'm not sure of the type of verification you want to conduct, so cannot be more precise.
Concerning the units, you should divide your formula by the plate width to get a correct result. Your formula is used for bidimensional plates, where the moment is expressed in lb in /in (called also a unit moment), so it is not incorrect, provided you use the correct definition for M.
prex
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Bending stress in horizontal press. ves. saddle base plate

dannyo

Chemical

prex

Structural

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