Bending stress in horizontal pressure vessel saddle base plate

[dannyo]

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.

 

[nicco]

the formula should be fb={(6*M)/[wb*(tb^2)]}, where wb is the base plate width

 

[ishvaaag]

What is implied in the first formulation is that M for the check corresponds to wb=1 in, i.e., is the moment that acts on a 1 in wide strip.

M in the second formulation would be the one acting in a full wb.