API 620 tank design 4

[alienitmeca]

hello

i am designing a vertical storage tank per API 620, i find this standart quit difficult to work with, specially when designing the shell and the roof, i could use a sample of the calculation, if possible, or any advice,

thank you in advance

 

[IFRs]

You don't need a sample. You need 10 years of experience, or someone you can learn from.

 

[fegenbush]

I agree with IFRs. Given the great variety of tank design options available with API 620, a sample is unlikely to do you much good. It could also be dangerous for you to believe you have the skills necessary to design such a project. Lawsuits are expensive, consultants are not.

 

[JStephen]

I believe there are some sample calculations in one of the Appendices/Annexes, I don't remember what all they cover.

The main issue with the standard is that it's written in such a way that it can be applied to a variety of tank shapes, which makes it much less of a cookbook approach.

 

[alienitmeca]

thx guys, that's actually what i needed to know, because i was starting to lose confidance in my skills,

i still have another question:

how long do you think it could take me to design a large vertical storage tank per API 620 now that you know that i have practically no experiance in this field ?

 

[fegenbush]

aliienitmeca,

The length of time it takes to design is proportional to the size. "Large" is insufficient information to determine appropriate scale.

 

[alienitmeca]

fegenbush

i dont see how the size of the tank is related to the time of the design, i beleive it has only to do with understanding the design steps, and calculations should not take a long time,

i would apreciate if you further explain your point

thank you

 

[fegenbush]

alienitmeca,

Depending on your background, you may think that a 20ft (6.09m) diameter tank is large. In comparison to most of the tanks I build, it is not. However, the larger the diameter, the more consideration is required for structural support of the roof, the shell-to-roof joint, anchorage, and foundation design.

On an API 620 project, determination of the thicknesses of the shell, roof, and floor plates are quick in comparison with the design details required for the aforementioned items. As an example, many customers request a single large tank (~150ft / 45.71m) which is physically possible, but not economical. Additional design considerations also come with refrigerated tanks or other low temperature service.

I hope that we have not been too discouraging to you, but it would be wise to seek a consultant on this project.

 

[alienitmeca]

fegenbush

actually, i am not designing the tank according to a specific diameter, i am suppoosed to establish a design procedur to be used for any tank dimension. i have already done one per API650, the one per API620 remains, so, as i already said, any example could be very helpful in my situation.

thank you

 

[IFRs]

650 is limited to one basic design while 620 tanks can take many shapes. You have your work cut out for you on this one! And you are building yourself a model that will need to be updated regularly as each code is updated and revised. You may be better off buying commercial software that is maintained as the codes change. I trust you are using the most recent version of each code now? I hope that the people using your design guides will have their work checked by an expert.

 

[alienitmeca]

IFRs

i am using the recent editions of both API620 and API650,

to reply to your question, no it will not be checked by an expert, however, it will be drawn on CAD software and tested .

 

[marty007]

alienitmeca,

As IFRs mentioned, API620 allows for a myriad of different geometries. Is your design going to be flat-bottomed like an API650 tank? Will it have conical sections? Will it be vertical or horizontal? Is it leg-supported, skirt-supported, saddle-supported, etc...?

I've gone through a few designs (by no means an expert if something unusual came up), but I know enough to wish you good luck in developing a single design procedure. API650 is like a cookbook for one type of geometry, API620 is everything else.

Sorry, I don't have any examples I can provide.

Good luck.

 

[alienitmeca]

marty007

thank you very much for your support and recomendations, as well as all other friends,
i believe am getting better every time i re-read the standard, i am sure it's gonna be a matter of time now.

thank you

 

[MJCronin]

alienitmeca,

The person who assigned to you this important, complex engineering tank design assignment...... does he have an MBA ? ? ?

MJCronin
Sr. Process Engineer
Venture Engineering & Construction

http://www.VentureEngr.com

 

[alienitmeca]

MJCronin,

i don't know that, but he has 6 years oil&gaz-related experience , however this is the first time he works on low pressure VST,

but i don't see the point of this question, could you explain more ?

thank you

 

[Duwe6]

I believe that MJCronin is aluding to a manager trying to save money by asignining a junior and/or inexperienced engineer to design his tank. Instead of hiring an experienced and fully qualified consultant to do the work.

But I could be wrong

 

[alienitmeca]

Duwe6,

you couldn't be more right, actually it's the strategy of the whole company, not my senior, any way i must have this job done perfectly. 1 month ago i new nothing about API 650, now i master it, and i am getting better every day in using API 620. i am getting a great deal of experience out of this project.

thank you for you support

 

[IFRs]

"master" is a pretty strong statement, I'm curious - how thick are your manway necks?

 

[alienitmeca]

IFRs,

i agree with you, "master" is a pretty strong statment.


IFRs, thank you for the advice.

 

[alienitmeca]

hello,

i have two questions that are related to shell design per API 620 :

-how to determine the number of courses constructing the shell, and the relative hight (h) of every course

- in the example (F1) given in APPENDIX F ,the assumed thickness in the beginning is t=3/4 in, i don't see how to choose a thickness for my case of design (is it t=3/4? , if not how do i know the right one?)

this is too important!!
thank you in advance