Storage Tank Vent sizing

[roggs28]

Hi All:

How do you size a vent pipe for a storage tank? More specifically, a vent to atmosphere for a 12000USgal tank. The tank inlet is 4", 6" O/F, 4" discharge. The vent pipe will be approx. 50ft long.

any ideas??

Thanks

roggs28

 

[KernOily]

Yep. Start with the MAWP of the tank as your source pressure. Calc dP across the vent line using your required vent/relief rate. Set exit pressure of line at 0 psig. Iterate line size until the source pressure (tank pressure) is <= tank MAWP.

Thanks!
Pete

 

[Zapster]

Review API 2000 “Venting Atmospheric and Low Pressure Storage Tanks” to determine the required flow. Then follow the advice given in the post above.

 

[JStephen]

Check whatever design code the tank is built to, to see if it addresses the question. API-2000 would generally be used for API-650 or similar tanks, but UL specs may just state a vent size in the spec.