Lightning Arrestors

I am sure that provision of lightning protection for aboveground oil tank is a must. Try API RP 545 (American Petroleum Institute) for more details.

You can also have a look at this. Note that some of other standards are also recommended at end of the report.

http://ws9.iee.usp.br/sipdax/papersix/sessao12/12.9.pdf

thanks a lit for the link. it was very informative. but i have not seen any storage tanks havin arrestors over the roof may be the provision is at the walls of the dyke farm area. anyways thanks again.

You then will need to have a chat with the lightning protection vendors especially in oil and gas field to have a clearer view on this.

The whole structure can be used as a lightning arrestor as we did with Cold Box. But if the tank has the instruments mounted around on it wall. It should have an arrestor.

Your second comment reminds me about the answer of my question. If we drop a lit cigarette into a bowl of petrol, the petrol will distinguish it. But if it lights the vapor before it hits the liquid...

Does it light up something?

i do accpet the provision to be compulsory, as there are codes which describes the designing n other aspects like NFPA 780, but none of the storage tank design codes indicate the need and the location of these arrestors. this makes it very difficult for us to ask the vendor with out any proper basis. anyways thanks for the info.

Several standards will just focus on materials or on how to erect the tank correctly because it is availabe other standards for protection. You should have a look at some additional standards like API RP 545 (Recommended Practice for Lightning Protection of Aboveground Storage Tanks for Flammable or Combustible Liquids) which will tell us how to protect the tank after we installed it.

If you have never seen any arrester on the top of tank, it is OK because it depends on what method of lightning protection being used.

We used to have problem with Cold box (CB) lightning protection, the CB was about 25m high and when we asked the supplier if it needs lightning protection? They said, no because the CB itself was an arrester. But month later, it was struck by the lightning. Yes, the CB is Ok but all the instrumentation was broken. Now, who can we blame? The designer said it is ok but the instrument manual said the instruments need protection.

Just go back and ask the tank maker or designer for this. I am sure that they will have the answer.

As hien.nguyenquoc says, the tank will need lightning protection. It may be provided by means other than commercial lightning arrestors, but you may need lightning arrestors to protect instrumentation on the tank.

If you need to buy commercial lightning arrestors, review the following posts and avoid the products mentioned:

• http://cr4.globalspec.com/comment/709103
  
• http://cr4.globalspec.com/comment/667868
• http://cr4.globalspec.com/comment/676167
  

Well, finally, this is what APR RP 545 says:

1. Install submerged shunts between the roof and shell every three meters around the roof perimeter, and remove any existing above-seal shunts.

2. Electrically insulate all seal assembly components (including springs, scissor assemblies and seal membranes) and all gauge and guide poles, from the tank roof.

This is submerged shunt: