Stainless Steel Storage Tank

[fred2002]

Can anybody suggest a suitable design code (British or European preferably) for a vertical stainless steel storage tank which will contain an acidic solution?

The tank will have removable heaters, probably electric, to raise the temperature of the contents to about 50 deg Celsius. Will this make it a fired or an unfired pressure vessel?

Due to access constraints, the tank will also have to be built up from various sections and either bolted together or welded in proximity to its final location.

Sorry this is a bit vague at the moment, but we are at the project scoping stage at the moment.

Thank you in advance for any answers

Fred2002

 

[JStephen]

API-650 App. S is one standard that could be applied to it. Assuming it is atmospheric, the heaters would not prevent it from being built under that standard.

 

[MJCronin]

fred..

The selection of the appropriate design code, tank features etc is mostly controlled by the design pressure.

Generally speaking, if it is over 15 psig, use ASME VIII, BS 5500 etc, if under 15 psig consider a flat-bottomed code such as API620, Under 2.5 psig use API-650 or it's euro equivalent....

My opinion only...

What is the temperature & pressure of your application ?

What is the volume cobtained and vapor pressure of the liquid ?

My opinion only

-MJC

 

[dig1]

If the tank is flat bottomed, has pressure limits of 500 mbarg to -20 mbarg, and temperature limits of between -40c and 300C then I would use EN 14015; check the document for exact scope requirements. EN 1993-4-2 may also be an applicable document. If you are a pressure vessel, then EN 13445 or BS5500 would be the applicable documents.

I hope this helps.

BR,

Patrick

 

[fred2002]

Thank you for your responses so far.

I've not heard of API-650 before, presumably it's an American standard. I wasn't aware of BS EN 1993-4-2 either, so I'll try and get hold of it.

The bottom will probably be conical shaped to help any sediment drain out. The tank it's replacing is flat-bottomed, though.

I presume the pressures you are referring to are static depth pressures. The maximum tank height will be about 1.5 metres and the depth of solution about 1.2 metres. So depth pressure = 1000*9.81*1.2 = 11772 Pa = 0.117 bar = 117 mbar.

5% acid solution temperature will be 50 deg celsius. The tank, although covered, will be open to atmospheric pressure. I would think that the vapour pressure would be similar to water. Tank volume is 400 UK gallons (~1.8 m^3)

I'm still not entirely certain if adding electric heating to raise temp to 50 deg C turns it into a pressure vessel which means that PD 5500 or BS EN 13445 need to be consulted.

I hope this clarifies a few issues.

fred2002

 

[gr2vessels]

No, the tank fitted with heating coils is not a pressure vessel. Please note that the mentioned API 650 can only be used for tanks with the bottom fully supported, ie flat bottom on flat soil or concrete plinth. If you design the tank as an atmospheric bin with conical bottom, it will be most likely supported on a ring or legs. In this case, your best bet will be BS-EN-1993-4-1. The heating could be internal electric coil or fluids like oil or even steam coil heating, in which case the coil itself will be designed, fabricated and tested as pressure piping. Your choice of pressure piping is unlimited, USA, South Africa, Norsok, Hungary, Australia, etc.. Best bet, buy the heating coils from an experienced manufacturer and ask for 10-20 years guarantees. He will use the most appropriate code, to support his guarantees.
cheers,
gr2vessels

 

[JStephen]

The pressure in a tank, for classification purposes, would be the gauge pressure at the top of the tank, not the pressure in the fluid at the bottom. A tank may be 10 or 20 meters high and still be an atmospheric tank.

 

[IFRs]

The OP states that the tank will be open to the atmosphere, so it will not be a pressure vessel. If the bottom is fully supported on a concrete or sand pad API 650 can be used. API 650 requires a 1:120 cone up bottom unless otherwise specified but is silent on the maximum slope of the bottom.

 

[Aconnell]

We have cone bottom tanks with steam coils for a similar application on our plant. Even though they are atomospheric we had them built to ASME VIII, Div 1, the designer also used API 650 as a reference. I do not know of a specific code which covers atmospheric cone bottom tanks.

 

[carthago]

Please be aware that there is an european Code for storage tanks.It is
EN14015 "Specification for the design and manufacturer of site built vertical, clindrical, flat bottomed , above ground , welded steel tanks.."

Thus flat bottom and welded..

This replaces the old BS 2425 or was it 2524 ??
Replaces the french CODRES ( which is similar to API 650)