Design of Circular Flat Endplate with Stiffeners 1

[aobjr]

I have been asked to look into designing a circular flat endplte with stiffeners havin a diameter of 3m~5m for storage (water crude oil, chemicals) horizontal tank. ASME Sec. VIII Div. I has discussed it but without stiffeners, so the resulting thickness is too big even atmospheric condition. Can someone recommend a design procedure/information? I have 5 reference PV books by Megyesy, bednar, Young,etc but does not discussed design procedures on this topic

In particular, I am unsure how to consider the interaction of bending stress, shear stress, allowable deflections. I'm in the Philippines, so my references are limited. I also surfed the internet but nothing so far.

 

[JStephen]

Don't over-complicate it. Treat a strip of plate as a fixed-fixed beam between stiffeners to figure the spacing of stiffeners. Then transfer that load to the stiffeners and design them as pinned-end beams. You could figure some width of the end plate as part of the stiffener as well. At the end of the beam, check bending in the plate itself to see if you need to attach the beam end to the shell, or can just end it on the plate. Be sure the beam compression flanges are adequately designed for the degree of support they have.

I believe UL 142 has some guidelines on stiffeners, but I don't recall the details- and it's an expensive standard, too.

 

[arto]

Azbel& Cheremisinoff's "Chemical & Process Equipment Design, Vessel Design & Selection" has a simplified method in chapter 7.7, where they assume the ribs take half the load.

 

[aobjr]

JStephen,
Thanks. Will try.

Arto,
Thanks. Basically it would take time before I could get the book as part of my additional reference. Can you provide advanced scanned copy at the moment? aobautista@bhpi.com.ph

 

[MJCronin]

aobjr...

Are you sure that you want to do this ?

Many times it is cheaper to purchase and install a dished head than it is to design, fabricate weld and inspect a flat head for a storage tank.

What is the diameter of the tank and why must you install a flat head ?


-MJC

 

[Rolando68]

If your vessel must comply with any of the Pressure Vessel standards, then I agree with MJCronin and you should look into using a formed head rather than a flat plate. If your vessel is non-code, then you can use the procedure described by Jstephen or use Rork's Formulas for Stress and Strain.

 

[jodyed]

You are correct Jstephen, UL 142 has an excellent, easy to understand design for subject baffles. Suggest you use the seventh edition.

Thanks,

jodyed

 

[jodyed]

P.S. to jodyed above:

UL 142 refers to the subject as: "Stayed Flat Heads"
Sorry to have used term "Baffles"

Thanks,

jodyed