Spherical tank, help please.. Thanx

1. You should design to whatever the specification/requirement of the end-user/client is. ASME VIII Div 2 gives a better engineered vessel with calculated stresses closer to actual stresses - a professional engineer is required, specifically for the user specification sheet. ASME VIII Div 1 will give a more conservative design. The greatest benefit to designing to Div 2 will be that thinner plates/materials can be used giving the advantage of cost savings in fabrication (the design/nde is more difficult and stringent though). I suspect that your LPG spherical tank is rather large, and the cost savings would be substantial. However, I would say (and not trying to be mean here) that you are not qualified, nor experienced enough to design to Div. 2. Even having said that, I hope that if you design to Div. 1 that your work is reviewed by an experienced engineer. The most difficult part of the design for a spherical tank is the loadings of the supports (and secondly any nozzle loadings), which ASME does not have formulas to spell out (the design of the shell and nozzles are relatively easy).
2. There are slight differences:
• ASME VIII Div 1: There are slight differences in the reinforcement required - please review UG-37, particulary paragraph UG-37(c).
• ASME VIII Div 2: Please review sec 4.5
• For actual nozzle thickness itself, no, there are no differences.

I am now registered user as a Premium. I am from Jakarta, Indonesia..

Thank you very much for the answers.. Actually, the internal diameter of my vessel is 22 meter.

Talking about the recommendation from client (end-user), they have not mentioned the specific standard in their specification (TOR - Term of Reference), but i have asked them, they simply answer "ASME VIII", with no specific "division". Actually this project is still in bidding phase (tender) for technical proposal. But the format of the bidding is "Beauty contest", which means only contractor with the best technical spec and affordable price that could be the winner. I do not know the relationship between this kind of tender with the availability of cleint recommendation standard.

Thank you for saying that i am not qualified, that was correct, because i am still a junior engineer and only a new graduate. Then please teach me Sir..

I am now designing the vessel using ASME VIII-1. I have calculated the minimum shell thickness which is 2.94 inch. And by using VIII-2, i got 2.55 inch.

Let me conclude this discussion before i propose new questions.

1. It is better for me to use div 1 instead of div 2. For your info guys, this project is a new one for my company, that is why NO ONE has good ability in this matter.

2. There are no differences in calculating nozzle thickness in spherical tank and cylindrical tank. (so it means that this is refer to ASME VIII-1 UG-45)

3. ASME does not have formula to calculate the tank suppurt (column). Then maybe i should refer to AISC then.

Ok, please let me propose two more questions.

1. Can i use two different ASME standard in calculating shell and nozzle. For example, i use ASME VIII-2 AD-202 to calculate shell thickness, and i use ASME VIII-1 UG-45 to calculate nozzle thickness. Can i do this?

2. Is there any practical rule to design spherical tank columns? Or is there any volunteer who wants to share with me about the fundamental in designing LPG spherical tank, from the material selection, how to calculate tank support, determine most economical design rule, etc.

Forgive me to ask you a lot of questions guys.. I hope you could help me. Any kind of answers will be appreciated.

Thank you very much..

Wow... that was horrible..

Sir, in what section in ASME VIII-2 that explaining about nozzle thickness calculation? To be honest, i am not familiar with Div2 (obviously, i am just junior engineer). I hope nozzle calculation in Div2 will be easy as in div1 UG-45 (sorry to say it "easy")

Ok will consider your input, evaluate the situation, and i will suggest to my supervisor.

Thank you for your brief answer..

In the lastest edition of Div 2 (2007) the nozzle thickness is given in section 4.3

The strictly "thickness" calculation is pretty straightforward; for a radial nozzle in a cylindrical shell:

t = [D/(2cosα)][exp{P/(SE)}-1]

where things get a little trickier are in the weld strength calculations, reinforcement calcs, external loadings, fatigue, .............

Like I also suggested by private message, if you aren't bidding against the pioneers of the Horton sphere, hire 'em .

Mr. Xmech

Thank you for mentioning the formula for calculating radial nozzle thickness.. But that is for cylindrical shell. What about for sphere? Same formula or not..

Thanx.