DESIGN METHODS AND STANDARDS FOR RECTANGULAR STORAGE TANKS 3

[jamesh8448]

I have been trying to find recognized standards regarding design of large open rectangular storage tanks. My company has acquired this product line recently with no backup calculations. There are many sizes. I would like to check the designs, and also determine what modifications are necessary to handle seismic loading.

 

[juancito]

Have a look in page 213 (in my edition) of the Pressure Vessel Design Handbook by Eugene Megyesy. From what I´m seeing right now there is no reference to specific norms but classic strength of materials authors.

 

[bdog]

Omer W. Blodgett's "design of Welded Structures" Published by the Lincoln Arc Welding Foundation has a section on Tanks, Bins & Hopper design that is similiar to the methods in the Pressure Vessel Handbook.

 

[twjag]

I recommend that you follow bdog's advice & use Blodgett.
Note that the method in Megyesy is limited to small tanks: 30cuft for unstiffened & 140cuft for stiffened tanks.

On several occasions I have used Blodgett to check calc's using Megyesy method, & found the Megyesy method to be unconservative for larger tanks.

The Blodgett book is dirt cheap, as are all of the good reference books available from Lincoln.

 

[abbver98]

See ASME VIII Division 1 Appendix 13
There is another method called Nodal Circle or Mohr method that consist on searching the equivalent circle of the form and reinforce the portions compressed or stretched. It's very simple method. The thk calc remains the same as it's for regular form. Welding joint have to be arranged far from stressed places.
John, Would you please send me the article? Thank you so much.

 

[abbver98]

Thank you John for e-mailing me the Flange calculation spreadsheet. For people who just receive it, you can withdraw the sheet protection by copying the file.
I supposed it's a new method of flange calculation but it's the commonly used in ASME code Section VIII division 1 Appendix 2. I don't run the calculation because I have the same sheet that I used many years ago. My colleague (senior engineer) has very perfect program that calculate the stress due to external load any origin (wind, seismic, punctual, …) and the shape factor are calculated with high accuracy using appendix formulas so he doesn't get tired to use a graphics.
I'm about to finish an executable program that calculate flange stress with any load, any flange type with some features :
*High interactivity and user-friendliness.
*Material library for flange with mechanical properties (YS, TS, A%, main composition, Sr, St).
*Material library for bolting with mechanical properties(YS, TS, A%, main composition, Sr, St).
*Material library for gasket with mechanical properties (m, y, type).
*Flange type drawing display.
*Technical Report text format, can be printed.
*Calculation according to the new European code EN13445 for Unfired Pressure Vessel Part 3 Chapter 11 that is the same as EN1591 : Flanges and their joints – Design rules for gasketed circular flange connections – Part 1: Calculation method.
*Material library for Standard European steel.

 

[jamesh8448]

The tank design methods I have seen are based on a very important assumption that the deformation is small (less than half of the plate thickness). This is impractical for the large tanks that I am dealing with. Measurements of deformation of actual large tanks are much less than these methods predict. Analysis methods must account for the non-linear geometric stiffness of the diaphram plates. Does anyone know of tables of coefficients based on the aspect ratio of a flat plate under non-uniform load?

 

[twjag]

jamesh8448,

Check out "Tubular Steel Structures, Theory & Design"
The James F. Lincoln Arc Welding Foundation
$15.00 US at

http://www.jflf.org

Chapter 7 "Bins & Bunkers"
Provides design by large deflection theory

 

[chicopee]

DONT BE CONFUSED BY THDIFFERENCES BETWEEN ASME BUILT TANKS AND NON-ASE BUILT TANKS. ASME TANKS ARE BUILD NORMALLY AS PRESSURE VESSELS. NON ASME TANKS WILL CONTAIN SOME PRODUCTS BUT ARE NOT DESIGNED TO BE PRESSURIZED , THEREFORE NOT REQUIRING FULL WELD PENETRATION, POST & PRE HEAT OF WELDED JOINTS AND MANY OTHER REQUIREMENTS. WITH TANKS DESIGN, MEMBRANE THEORY IS USED AND THERE ARE MANY REFERENCES READILY AVAILABLE ON THE SUBJECT.

 

[jamesh8448]

chicopee:

I would be interested to know what references you refer to for tank design based on membrane theory. I have not been able to find anything that addresses large deflection analysis of rectangular flat plates subjected to non-uniform pressure. I have seen a table in Roark for large deflection of flat plates with uniform loading, but not hydrostatic type loading.

 

[arto]

There is a good old Machine Design article on membrane vs. plate vs. thin plate:
J.A.Martinelli,"Stress Analysis of Pressurized Panels," Machine Design, Dec. 9,1976, pp149-151. This should be available in engineering college libraries, or on the desk corner of your nearest ancient engineer

He has you calculate the stress & deflection by the various methods - if defl>10*t, then it's a &quot;membrane,&quot; if defl<0.2*t, it's a &quot;plate,&quot; if between these, it's a &quot;thin-plate&quot;

 

[chicopee]

The books are as follows:1)&quot;Pressure Vessel Design Hdbk&quot; by Henry H Bednar; Chapter 3 deals w/ membrane analysis
2)&quot;Tubular Steel Structures-Theory & Design&quot; by Triotsky and published by the James F. Lincoln Arc Welding Society.
Deflections are within the elastic range and not in the plastic region with the analysis presented above. No large deflection-
Timoshenko as an analysis for large deflection of beams however this is not what you are looking for.

 

[hockchong]

Anyone have any idea how to check external loading of nozzle on the flat plate e.i on the rectangular tank. Thanks for the help.