How should freeboard be determined ?

[MJCronin]

I am having trouble finding any guidelines on establishing what is reasonable "freeboard" for a small process chemical tank. ( An FRP tank less than 10,000 gallons)

(Freeboard is defined as the distance from the bottom of the overflow connection to the top of shell)

This is NOT a SEIMIC TANK DESIGN (I am aware of the API-650 requirements for freeboard in a seismic design i.e. to prevent excessive roof loadings during a "sloshing event")

What are reasoonable numbers ? 6 inches....12 inches ? ZERO ?

Is there any reference of guideline available ?

Does the amount of freeboard in the design depend on the tank loading method ?

Is it just a guess ?????????????

 

[fegenbush]

The general API usage is 0.7 times the calculated wave height. I would use this value as a starting point then adjust for ease of fabrication.

 

[IFRs]

To a large degree it depends on your fill rate, your containment capacity around the tank, the severity of issues should there be a overfill condition, your ability to monitor your fill rate, your high-level sensors and alarms and how long it takes to turn off the fill pumps in the event that your high level sensors activate. API 2350 covers most of this in detail and would be a good guide.