tank design standard

[alienitmeca]

Hello, i want to design a vertical tank for slug to produce biogaz, the probleme is the internal pressure may exceed 15 psig wich the maximum design pressure allowed by API 650

I need to know if there is another standard i can use in this case knowing that the pressure maybe close to 70 psig.
thank you in advance

 

[LittleInch]

You mean API 620 which is up to 15psig, not API 650 which is only up to 2.5 psig

After that you're really looking at a pressure vessel to ASME VIII or similar pressure vessel code in whatever country or location you are in. 70 psig is quite high if your tank / vessel needs to be a significant size.

You could also look at making it out of normal pipe if the volumes are not too large or if you have a lot of space.

What volume / size/ length are you looking at?

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[alienitmeca]

thx littleInch for your reply
i am interested in american standards only, i understand from your answer that neither API nor ASME BPVC can be used to design a vertical storage tank working under high pressure (70 psig) , tank diameter =15 meter, tank hight= 30meter

 

[LittleInch]

Err, no. Neither API 650 or 620 extend beyond 2.5 or 15 psig respectively.

A 70 psig tank or pressure vessel that big is just unreal. Also why is this so high?

A pressure vessel can be any size as far as I know, but something this big would be uneconomic and perhaps not feasible.

I think you need to go back to basics here and look again at your process conditions, but in theory an ASME VIII vessel could be built.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[marty007]

I agree with LittleInch, pressure vessel of that size would likely be uneconomical. For that pressure and volume, you may want to consider multiple tanks. This would allow shop fabrication with relatively easy shipping. That said, you would need a lot of vessels for that volume... I'd recommend you either reconsider your volume requirements or your pressure requirements.

 

[alienitmeca]

marty007 and littleInche,

i aprechiate very much your help, your replys were very helpful and informative.

 

[fegenbush]

If you or your client are set on a single vessel, it is possible to accomplish this using a sphere. Depending on the actual working volume requirements, between 74 ft (22.6 m) and 76.5 ft (23.3 m) diameter would be the size. This is a reasonable size and pressure rating for a pressure sphere to avoid PWHT of the entire vessel.

The pros of using a sphere are very efficient use of steel plate thickness for the pressure and maintaining only one vessel. The cons are cost (both from increased fabrication cost and a reduced number of fabricators capable of completing the work) and time of completion.

 

[alienitmeca]

fegenbush,

much apreciated, after doing my research it looks like i'm designing a digester for biogaz, so, it looks like i am the one to set the pressure inside the tank according to my needs, not the client, as a conclusion, i a designing the tank so the release pressure of the biogaz do not exceed 15 psig which allowed by API 620


i can't tell you my friends how happy i am to see you responding so quickly to my threads, i hope i can do the same.

 

[LittleInch]

30m high, but only 15 m diameter is still looking very odd to me and I think you need to talk to some vendors to understand what is possible for different pressures.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[JStephen]

That pressure is something to watch very closely. Once you get it into the scope of API-620, you still have a situation where any variation in pressure will make a corresponding change in price. Also, if the tank is built as a flat-bottom tank, foundation size and details will vary accordingly.

 

[alienitmeca]

the hight of the tank may be changed, it doesn't hove to be 30m, but i still need the insight of someone who have had the chance to design a digester,

 

[MartinLe]

Can someone close the other two of the three threads the OP started*? This is confusing already.

Also can you, alienitmeca, make a concise list of the requirements you actually know and the ones you are guessing?

My gut feeling is that this problem is pretty simple and you should talk more to whoever asked you to build/design a tank. My other gut feeling is that you don't need much pressure.

I'm sure we can help you, but you need to make it easy for us to do this - by narrowing down the problem and not starting so many threads.


*IMHO these should be closed:

http://eng-tips.com/viewthread.cfm?qid=360238

http://eng-tips.com/viewthread.cfm?qid=360202