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Galadanchi
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Join Date: Jan 2013
Posts: 3

Earthing of Fuel Station's Underground Storage Tank

01/24/2013 4:02 AM

I want to earth a fuel station's underground fuel storage tank. If the base of the tank is buried at say 5M below the surface level, can the lower tip of my earth rod be at 3M below the surface level? That is at a level above the base of the tank? Please assist.
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PWSlack
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#1

Re: Earthing of fuel station's underground storage tank

01/24/2013 4:14 AM

Beware galvanic corrosion. What are the materials-of-construction of both the tank and the earth rod, please?

What is in the tank, its temperature and pressure, please?

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Galadanchi
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#3
In reply to #1

Re: Earthing of fuel station's underground storage tank

01/24/2013 5:33 AM

The tank is made of steel and the earth rod is made of copper. The tank temperature is betwee 30 to 45 deg.C and for its pressure it can be up to 3 bar.
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PWSlack
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#6
In reply to #3

Re: Earthing of fuel station's underground storage tank

01/24/2013 6:25 AM

Then the best thing to do would be to isolate the tank electrically from the earth rod, and rely on the groundwater making the earth connection between the two. Were the two items to be connected electrically through some form of earthing network, then the steel tank would corrode and over time the material in the tank would leak out. Not knowing what the material is inside the tank could mean either:

  • a fuel vapour cloud above the tank looking for a source of ignition, or
  • a leak of fuel liquid into the local groundwater, or
  • some combination of both

Refer to local contruction codes for fuel tank installations, as indicated in #4↓, and go from there. If a local code is not available, or not applicable, then borrow a national code from elsewhere, such as British Standards.

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The.Tinkerer
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#8
In reply to #6

Re: Earthing of fuel station's underground storage tank

01/24/2013 2:49 PM

Not sure what country OP is in, but under US law (Title 40, Part 280), the tank must be coated with a suitable dielectric material. Using the steel tank (and groundwater, if/when there is any) as part of the earthing system is not acceptable.

If the groundwater were to go away, there would be no earth connection and a difference of potential would be looking for a way to make itself known.

CFR-40, Part 280.20 also provides some other industry standard titles, including Canada's.

Here again...I don't know what country's laws apply to the OP.

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PWSlack
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Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
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#9
In reply to #8

Re: Earthing of fuel station's underground storage tank

01/25/2013 5:05 PM

In that case it would not be possible to ground the tank were it to be installed in the US, and therefore the original poster's quest is not viable. GA for the useful snippet, as several CR4 readers are in that country.

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PWSlack
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#2

Re: Earthing of fuel station's underground storage tank

01/24/2013 5:19 AM
  • What is the nature of the medium in which the tank is buried and how wet is it on an average basis?
  • How far down is the average water table?
  • What features are in place to stop the tank becoming a boat?
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Galadanchi
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#5
In reply to #2

Re: Earthing of fuel station's underground storage tank

01/24/2013 5:41 AM

The tank is buried in sandy soil. The water table is about 2M down. The tank was bolted on top of reinforced concrete base using metal belts.
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pnaban
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#4

Re: Earthing of fuel station's underground storage tank

01/24/2013 5:37 AM

Refer codes.

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 pnaban
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The.Tinkerer
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#7
In reply to #4

Re: Earthing of fuel station's underground storage tank

01/24/2013 2:39 PM

I can't believe the comments got this far without someone stating the obvious.

It doesn't matter what we think or what is right...it matters what the code (or law) says!

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Galadanchi (2); pnaban (1); PWSlack (4); The.Tinkerer (2)

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