Emergency vent sizing for ATM Tank - API 2000

[Nik456]

For one of the storage tank (non flammable material- Flash pt >200F) has the capacity of 29000 Gallon (100,000 Liter). I have sized the normal vent for breathe in/out, which is atmospheric vent with bird screen.

I would like to know if i have to design the Emergency vent for this tank for fire case.

If I have to design emergency vent, what equation and releasing condition do I have to use for fire case.

The tank doesn't have frangible roof.

Thanks!

 

[ehsanunderline]

never vent of tank sized for fire case because it is very large size... emergency vent shall be considered

 

[Nik456]

I found following statement from one of the chemical engineering forum:

"API2000 standard basically supports the following emergency vent exceptions:

EXCEPTION #1:
Emergency venting for fire exposure is not
required if the tank is larger than 12,000 gallons
US and flash point is not less than 200 Deg F; and
tank is not exposed to other liquids with flash
point <140 Deg F "

Is there any reference to this statement? I couldn't find in API 2000. Is it still applicable to 6th edition?

 

[greenche]

Nik,
See NFPA 30 section 22.7.1 for this exception.

 

[Nik456]

Greenche,

Is it also applicable to API 2000?

 

[greenche]

API 2000 does not in all cases give absolute requirements on which potential causes of overpressure are applicable to a particular tank. This may require evaluation based on the particulars of the tank. It's good to have a sound engineering basis for determining applicability of scenarios and for the fire case some organizations use NFPA 30 as the criteria for applicability.

 

[CMA010]

What about construction code requirements of the tank?

 

[Nik456]

API 650/12F

 

[shahyar]

I am working in water treatment units of the oil industries dealing with water tank design.
1. In some cases "client" decided to ignore fire case because the liquid is non flammable and in some other cases they asked to include fire case as a valid case because "the tank is in vicinity of an oil plant".
2. Use API 2000.

Hope this help.

 

[proinwv2]

I would suggest that a fire can cause the tank contents to boil, and raise the pressure in the tank, if adequate venting is not available.

Careful consideration should be given to this. API 2000 6th edition in para. 4.3.3.3.2 has an equation for determining the required venting capacity, based upon heat input, latent heat of vaporization of the product, boiling point, and MW.





Paul

http://www.ostand.com