ERV design at top of storage tank 2

[OPS M]

Hi all,

First of all I'm not engineer.

So, Why the ERV emergency relief valve location at side not in the center at top of storage tank?

What is the reason?

According to API 650 all storage tanks ERV designed to the side.

Thanks.

 

[pennpiper]

OPS M,
Point one: An ERV on a Storage Tank should be checked by Operators and Maintenance Techs on a regular basis.
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Point 2: The roofs of Storage Tanks are subject to corrosion rotting of the under side (inside) where it is not visable. This weakens the roof plated and has resulted in people walking on the top, hitting a weak point and falling through.
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Point 3: Any thing requiring periodic attention (ERVs and Level Instruments) are grouped (or should be) and located near the Tank edge and at the top of the access stairs.
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Point 4: The tank top where these items are located should have a small area of Platform Grating added to the Tank top for walking and working.

Does that help>

Sometimes its possible to do all the right things and still get bad results

 

[OPS M]

Pennpiper,

Thanks for your valuable reply.

The platform can provided to reach the center.

I believe there is different reason, Why an ERV not installed in the center of storage tank?

Thanks.

 

[pennpiper]

OPS M,
You wrote: "I believe there is different reason, Why an ERV not installed in the center of storage tank?".

Okay, so what is the "other" reason?

Sometimes its possible to do all the right things and still get bad results

 

[OPS M]

Sorry Penpiper.

If I had the answer I will not asking and looking for it.

Thanks.

 

[gerhardl]

Pennpiper's good answers illustrates 'the engineers' way of thinking: what practical issues must be considered before any decision is made?

On the other hand: is there anything else either hindering or making it necessary with a top placement of an ERV?

Constructionally I cant think of anything, apart from special local construction details or surroundings, that could prevent a top placement of an ERV.

The direction of the release from ERV (either pipeline or free, or if the ERV is a bursting disc) could, under circumstances, favor a top placement.

I do no know if API 650 directly forbid or prevent top mounting, but I do not think European regulations prevent this. If you remount a complete vessel with a side-mounted ERV by turning it 90 degrees and lay it on its side, I do not believe you have to move the ERV, or rotate the tank to make the ERV side-mounted.

Or am I wrong?

 

[LittleInch]

OPS M - Would you care to share with us why you believe API 650 " According to API 650 all storage tanks ERV designed to the side."??

I've just searched API 650 and can't readily locate any such stipulation. Please advise clause number. If someone just told you "The reason is because API 650 says so", ask them for the clause number. When they don't get back to you then it falls into the many cases where someone believes something o be the case without actually checking it or confirming it.

Having said that I agree with pennpiper - easy and safe access is the most important feature.
plus cost - why would you spend more money building a safe walkway across the roof when you don't have to? Hence location close to the top of the access stairs is the best location - but doesn't mean it is mandatory.

If you've ever walked over a fixed roof tank when it "springs" a bit as you do so then you'll understand why operators don't fancy doing it on a regular basis.




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