Internal FLoating Roof Requirement

[yanuarsaja]

HI all,
as per the Tittle, is it Non Mandatory/Optional to Install Secondary Seal.
Refer to API 650 Appendix H :

"H.4.4 Peripheral Seals
In addition to the required floating roof primary peripheral seal, secondary peripheral seals shall be provided if
specified on the Data Sheet, Line 31. Floating roof primary and secondary peripheral seal types and configurations
shall be provided as specified on the Data Sheet, Line 31.
H.4.4.1 A peripheral seal (also referred to as “rim seal”) that spans the annular space between the internal floating
roof deck and the shell shall be provided.... "

What is the industrial practice commonly used for internal floating roof?

Thank you
Yanuar

 

[bimr]

Would depend on the application wouldn't it? What are you storing?

 

[IFRs]

API does not care or specify what seals to use. The requirement for any seal, a primary only seal or a primary and secondary seal comes from the environmental regulations in your country / state or province or region. The tank owner can specify better seals than required if desired, for odor control, emissions reductions or safety reasons. Various seals and seal combinations have different efficiencies, some have not been measured or documented so watch out for those.

 

[LittleInch]

An internal floating roof is generally understood not to provide sealing, with or without secondary seals whereby the inner void would not, over time, have the potential to be heavily filled with the vapour of whatever is in the tank. The key is then what happens to that vapour space as the roof rises and falls. If this space is kept inerted and or sent off to a vapour handling unit then a secondary seal would seem superfluous. If however the void space is free vented and the roof is only there to relieve rain or snow loads on the floating roof or is a retrofit, then secondary seals would be more likely.

So basically its an option - only you hold the information as to whether this is a good option or an unnecessary cost...

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[Syahar1975]

I did install the alumunium floating roof inside the dome roof tank.

We only have primary seal (rubber type) no secondary seal.

 

[yanuarsaja]

Hi...thanks for the input.
The fluid is condensate and we olan to use ponton type.
There is circulation vent will be installed on the tank.

I think we also wlwill use alumunium floating roof.

Another question, is iit mandatory the liquid directly contact to floating roof?
We keep some distance beetween liquid level and the floating roof..

Thank you
Yanuar

 

[IFRs]

In the USA, the EPA says that you must keep your floating roof floating.
If you don't, it is not a conservation device, just an expensive sieve and serves no significant purpose.

 

[Duwe6]

"Another question, is iit mandatory the liquid directly contact to floating roof?"

It is not practical to bridge a floating roof across the entire tank, and it seems a little silly to have a bunch of pontoons scattered about the underside of the roof to keep it dry. And the underside will not be dry; the air trapped under the floater will be saturated with your product, and some will condense on the floater. And, because the floater is elevated, that area will remain oxygenated, giving a LOT of corrosion. "There is always a good reason why things are done they way that they have been done" If nobody else in the world has an air-gap under their floater, you probably should reconsider your idea.*

*I'm good; sometimes I'm extremely good, approaching brilliance. But I will never be as good as the combined knowledge, talents, and experience of the rest of the world.

 

[LittleInch]

"We keep some distance between liquid level and the floating roof.."

How?? - anti gravity pads?

More importantly why? It seems to make little sense to go to the trouble and expense of a floating roof then have it not resting on the liquid surface where it significantly reduces vapourisation of the fluid

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[IFRs]

If the OP means: is a full-contact floating roof required ( vs a non-contact skin-and-pontoon style, the answer is "no" but some owners prefer the full-contact variety for strength, emissions, safety, long life, etc. Again there are many to choose from these days...

 

[yanuarsaja]

Hi all...
Sorry for unclear question.

To be honest.. I am new in designing the storage tank.
Attached vendor drawing from existing equipment.

There is a air gap between liquid level and the floating roof = half Dia. Of ponton.

I think,1st question is about the concept how to select type of internal floating roof as the starting point to design it.

Again.. Thank you very much for all the input.

Thanks
Yanuar