Air Pocket in Fuel Tank?

[MikeHalloran]

Imagine a truck saddle tank. Now turn it upside down, and put the fill and vent pipes on one side. There's an air pocket on the other side that you can't fill with fuel. You can only put ~80 gallons into what is nominally a 100 gallon tank. Aside from the reduced capacity, is that a problem?

Actually, the tank is built into a standby Diesel generator skid by welding plates between channels, and because of the engine bearers, that's how it turned out. Material is all mild steel.

It will eventually go into service on an oil rig off the coast of Africa.

What codes/standards/customary practices should apply?



Mike Halloran
Pembroke Pines, FL, USA

 

[MintJulep]

Does the geometry create any "low spots" in the unfillable portion that would not be able to drain by gravity into the rest of the tank?

If so, I can imagine water collecting in them over time due to condensation.

 

[BigInch]

A very short time, being offshore.

"If everything seems under control, you're just not moving fast enough."
- Mario Andretti- When asked about transient hydraulics

http://virtualpipeline.spaces.msn.com

 

[MikeHalloran]

No undrainable low spots.



Mike Halloran
Pembroke Pines, FL, USA

 

[Compositepro]

If you have an unvented vapor space at the top this vapor will expand and contract which could cause fuel to spray out when you open the fill cap.

 

[MikeHalloran]

The fill cap side is vented by a standpipe with flame arrestor.



Mike Halloran
Pembroke Pines, FL, USA

 

[IRstuff]

I think the post was regarding the other, sealed side. If the air pocket were filled with cold air at some point in time, and trapped there until it was hot, there might be sufficient air pressure to push the fuel out through the fill pipe.

TTFN

FAQ731-376