Above Ground Fuel Storage Tank

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rgwilliamson

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A question I can't find an answer to:
What is the classification of the area surrounding a double-wall above ground tank storing fuel products?

Some say it would be Class I Div 2 for a 10 foot area around the tank, another opinion is that the secondary containment (outer wall of the tank) allows for the area around the tank, exclusive of any hazard classifications due to piping, dispensers, pits, etc., to be unclassified.
 
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wlittle

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Location
midwest
Above ground storage tank

Above ground storage tank

I believe that table 515.3 lays out class 1 div 1 for the area within 5' of a vent, inside a fixed or floating roof on the tank, and any area inside a dike withere teh height is greater than the distance from the tank to teh dike for more than 50% of the tank circumference. (this is a tad grey, hope someone may be able to clear that up, but i think it means if you have an 8' tank, and the dike is 4' or less away from teh tank, that area is class 1 div 1 too).

class 1 div 2 is located in that 10' area - basically from most parts of the tank - and the area between 5' adn 10' from vents.

rgwilliamson said:
A question I can't find an answer to:
What is the classification of the area surrounding a double-wall above ground tank storing fuel products?

Some say it would be Class I Div 2 for a 10 foot area around the tank, another opinion is that the secondary containment (outer wall of the tank) allows for the area around the tank, exclusive of any hazard classifications due to piping, dispensers, pits, etc., to be unclassified.
Click to expand...
 
rbalex

rbalex

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Location
Mission Viejo, CA
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Professional Electrical Engineer
wlittle said:
I believe that table 515.3 lays out class 1 div 1 for the area within 5' of a vent, inside a fixed or floating roof on the tank, and any area inside a dike withere teh height is greater than the distance from the tank to teh dike for more than 50% of the tank circumference. (this is a tad grey, hope someone may be able to clear that up, but i think it means if you have an 8' tank, and the dike is 4' or less away from teh tank, that area is class 1 div 1 too).

class 1 div 2 is located in that 10' area - basically from most parts of the tank - and the area between 5' adn 10' from vents.
Click to expand...
The application as you cited it is primarily for cryogenic applications. For more general applications, assuming the product does need electrical area classification, see the text and diagram for NFPA 497 5.9.4(a).
 
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clarice

Member
Bonding grid under LPG Fuel Storage concrete slab

Bonding grid under LPG Fuel Storage concrete slab

Hi Guys - We are installing the slab and a bond ring for LPG storage tanks on a military base here in Hawaii. I am concerned about the placement of the 3-0 ring and ground rods under the 100' x 30' pad. Should this ring be tied into the enormous amount of rebar? Each tank (18 total) has a pigtail coming up through the top of the slab as a tank bond.

I'm apprehensive about the design! Any feedback will help.
 
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