Double Wall Tank Annulus Covers 1

[rab1944]

Is anyone aware of a limitation for the size of double wall tank that can have a roof over the annulus space. This may go into NFPA 30 and I am caught between a customer and an engineer. The enginner says that there is a 20,000 gallon thresshold for tank with a covered annulus.

Thanks for the consideration.

 

[JoeTank]

I've never heard of such a limit. I have designed several tanks in the one-million gallon plus range with covers over the annular space.

Joe Tank

 

[carthago]

Could you please give more information or direct me to specific vendor for this specific type of covers.

Sending sketch or indicating specialized vendor would be helpful

I am dealing with a double containment tank , with a cover above the annulus.

The inner tank has a dome roof and I have no question there.

Thanks

 

[JoeTank]

I was in one yesterday. 150ft diameter tank with a 156ft diameter outer tank. The 3ft annular space was convered with a conical roof of 3/16" thick plate. Radial stiffeners were used to support the roof about every 6ft. A very simple layout. Rafters were weld to both tank shells. Ventilation fans were provided

Joe Tank

 

[rab1944]

Thanks for the confirmation.