Anchor bolts and grounding lugs

[Syahar1975]

Good morning all,

We have plenty of anchor bolts on our tank.

In this condition do we need grounding lugs ?

Your comments is highly appreciated.

 

[fegenbush]

Anchor bolts will not provide the same grounding effect as a proper grounding lug connected to either a ground rod or ground circuit. Grounding lugs, for one, are stainless steel per API 650 so as to provide a better connection (no coatings). The cost of grounding lugs is small in comparison to the effects of an emergency caused by an improperly grounded tank.

 

[bimr]

You need grounding lug on the tank as well as one on the tank foundation steel.

It is important that all of the metallic components in the tank farm are bonded together.

 

[valleytank]

You will find ground lugs much more effective as well as they are typically connected via heavy gauge wire to grounding rods which are driven a fair length into the ground while your anchors are only embedded into your concrete.

 

[bimr]

Exothermically welded connections are preferred.

Since grounding conductors are usually copper, and grounding clamps are usually copper alloy or steel, you make a bimetallic couple (copper and steel) when using a clamp. In the presence of moisture, a corrosion cell occurs in which the steel corrodes to protect the copper. No matter how tightly you bolt the connection, the bimetallic interface still exists; and so does the corrosion, which increases the connection's resistance.

The exothermically welded connection eliminates the conductor-to-steel bimetallic interface. A welded connection has no mechanical interface in the electrical path between the two dissimilar metals. Therefore, no bimetallic corrosion can occur in the current path.

http://ecmweb.com/content/hard-facts-about-bonding-steel

 

[Syahar1975]

Good morning Gents,

Thanks for the response.

BIMR,

I have never heard Exothermically welded connection. But yes this is very good info that I would addressed in the future projects.

 

[IFRs]

Not only that but anchor bolts are not tightened, per the code. They form a really poor electrical connection. They are not tied into the plant grounding system.

 

[darthsoilsguy2]

tank questions should always include minimum information about the configuration of the tank, contents, and preferably design code it was built to. to throw a little hyperbole into the mix... there are some swimming pools, sludge holding bins, and many large electrical transformers out there which meet the tank description we have and have much different requirements for electrical grounding. That said, there are thousands of fuel storage tanks (both API650 and STI) out there with lots of anchor bolts and a separate grounding system.