Requirements for Cargo Tanks and tank support FEA-p- looks good so far

From: Hans Jostlein (
Date: Fri Jun 24 2005 - 11:00:20 CDT

I found the attached info using Google.

It states a minimumthickness of 0.187" (4.75 mm)
The Braidwood tank as analyzed has a 6 mm wall thickness.

The URL to the info is

I have also attached Ang Lee's FEA of the sphere and its support.
I don't know if this has been posted as a note yet -- it should be

A first reading unearthed these facts:

a. The code allows stress up to 25% of tensile strength.
Ang Lee's analysis shows under 4200 psi for the sphere, with anallowable of
21,000 psi

b. The code uses a "longitudinal deceleration of 2 g"
They are conmcerned with pressure buildup at the front end of the tank at
This acceleration must not create stresses larger than 75 % of the ultimate
We meet that requirement easily.

c. From Ang Lee's analysis, Table I, we see that:
The stresses in the sphere have a safety factor of 21,000psi / 4200 psi = 5
The stresses in the steel pads have a safety factor of 3
The stresses in the column legs have a safety factor of 2.25
The last two items can be beefed up inexpensively to whatever safety factor
is desired.
As an example, a safety factor of 3 would meet requirements up to 2 g
dynamic loading.

I will write a draft response for NUSAG along those lines.



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