Emergency overfill nozzle in external floating roof possible/advisable

[inammanj123]

Hello,

I have a 44 m dia water buffer tank. Client is asking for a external floating roof and also an overflow nozzle. Considering seal system, is overflow nozzle advisable.
As per C.3.1.1 of API 650 overflow opening can be provided, SO what need to be considered when locating overflow nozzle, I mean it should be above HHLL, and any special consideration when selecting seal system, so that it doesn't interfere in operation of overflow nozzle

Regards,
Inam

 

[LittleInch]

It should be above HHLL but below max roof height.

Apart from wondering why you have an EFR for a water tank, there are many types of overflow. - what's wrong with a dome roof or does the client like spending money he doesn't have to?

You could have holes simply cut into the tank shell will little spouts or you could have pipe(s) which extend through the roof with holes cut into the pipe at the required height if you're worried about roof seals which go down into the tank and out at the bottom through a nozzle. Less splashing that way.

All depends on your max inlet flowrate.



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[HTURKAK]

Mr. inammanj123,

Pls ask to the client to show a water tank constructed with floating roof.. Ask also the EFR seal manufacturers what type of seal is appropriate for water storage tank..

 

[inammanj123]

I agree that floating roof for water service is not seen. I also prefer stiffened dome roof. I am discussing with process to know the exact reason for floating roof

Secondly the exact service is waster water, so maybe due oil in water they are asking for floating roof. what do you guys think.

Regards,
Inam

 

[inammanj123]

Hi,
As mentioned above tank is for waste water service. Additionally The tanks shall be also provided with an adequate overflow line to route any excess flow to the existing Firewater/Storm Water Basins. Overflow shall be constructed with an internal dip pipe so that the oil layer on the top of the tank is retained within the tanks. In case of floating roof tank, kindly suggest possible arrangement of overflow dip pipe with floating roof present.

 

[LittleInch]

without actuated valves or pumps I can't see a way of having an overflow which operates below the top level of any oil or floating debris.

You might be able to come up with some sort of sliding collar, but it's quite odd. I'll sketch something up later.

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Also: If you get a response it's polite to respond to it.

 

[inammanj123]

Dear LittleInch,
Thankyou for your feedback. If possible kindly send some data on the actuated valve or pump and how it can allow an overflow nozzle in a floating roof tank.

When you have time , kindly do send some sketch for sliding collar system.

Regards,
Inam

 

[LittleInch]

OK, I've just sketched this up but never seen it in practice because what you're asking for is rather odd.

However what this is a top hat sliding sleeve intended to be pulled up by the roof structure.

If you locate the holes in the right location and the sleeve the right length then it should allow a certain amount of liquid above the holes in the overflow.

Just an idea....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.