oil and vapour come out from roof legs
oil and vapour come out from roof legs
(OP)
Dear all,
our tanks is a floating roof double deck dim.88m.The problem is that oil with vapor come out from some legs. I have checked the pontoons and are okay.
As far as I know if there is a vapor should come out from vents. you will find attached some pics.
our tanks is a floating roof double deck dim.88m.The problem is that oil with vapor come out from some legs. I have checked the pontoons and are okay.
As far as I know if there is a vapor should come out from vents. you will find attached some pics.





RE: oil and vapour come out from roof legs
If it is from the leg, you are getting hot fumes condensing and dripping down the sleeve. The 'fix' would be to add a wiper seal to the sleeve. Is the oil in the tank hotter than the air temperature?
RE: oil and vapour come out from roof legs
No thing with the base of sleeve it is coming out throw legs
RE: oil and vapour come out from roof legs
RE: oil and vapour come out from roof legs
Picture 2 shows the same - same leg?
Picture 3 is different - the sleeve is not stained, this could be a small leak at the repad?
Picture 4 is similar to pictures 1 and 2
If these are the only legs that have this issue, are they above the fill line and could the fill condition be turbulent enough to splash liquid up through these sleeves? If not the liquid fill, are you pigging into the tank, which could cause similar turbulence?
RE: oil and vapour come out from roof legs
Is that wiper as a seal accepted by API 650 BECUSE OUR TANK IS API650>??
Dear IFRs:
your answer really interesting we do some times pigging in the pipeline to the tank. I have attached new photos they may give you all complete picture.
Cold you explain to me more what do you mean by "are they above the fill line and could the fill condition be turbulent enough to splash liquid up through these sleeves?"
is there any relation if the current crude in the tank has lower or higher API??
RE: oil and vapour come out from roof legs
To the extent that thinner liquid can flow easier, or splash through thinn places, yes, the API of the liquid is a factor.
If you have a liquid only diffuser and you bring gas into the tank through that line, there may be turbulence, it can be dramatic and it can create enough action to bring liquid up through sleeves. If the legs in question are in one area omly, see if they are in line with or above the fill pipe.
RE: oil and vapour come out from roof legs
RE: oil and vapour come out from roof legs
I will pass to you all information you requested within today. Please keep in tuch
RE: oil and vapour come out from roof legs
Please find attachment Nr.1 the sketch for the the tank I will send you the other DWGS
RE: oil and vapour come out from roof legs
RE: oil and vapour come out from roof legs
please note that our tank is just 7 years old. this thing happened some days ago , the weather was quit hot and MAy ( I am not sure) after the deck was landed and the tank refilled.
RE: oil and vapour come out from roof legs
This looks like a typical external double deck floating roof with a pantograph shoe seal and secondary compression plate seal. These types seldom have buoyancy or strength issues unless there was serious erection quality issues.
If the roof drains were closed and deck was overloaded with water from a storm, I would think that more legs would show oil and you would have widespread staining.
Since it is a double deck style, bad welds around the leg sleeves are an unlikely issue and since only a few legs are showing this, severely leaking compartments are not likely either.
It is hard for it to be vapors since the underside of the floating roof is normally in full contact with the liquid and while there could be some, you'd need a lot to condense into that much liquid, particularly in the hot summer months.
The sleeves are very tall and getting the floating roof that low in the liquid is quite unlikely.
I'm liking the idea that there was a turbulent fill event that splashed liquid up through these few sleeves, perhaps pigging or butane blending, etc. Bear in mind that getting liquid up through these small spaces in the leg sleeves is not easy, it would have to be quite turbulent.
If the rolling ladder froze up and held the floating roof down, I'd expect to see more and widespread liquid staining in other areas.
Question: do you have fill and suction pipe drawings?
Question: were the legs changed from low to high and position and back recently? If you pull a leg up, it may hold some liquid which might spill out.
Question: please help me understand what items 21 on page 9 of 12 of the tank drawings set are used for ( spherical caps )
Question: what does the floating roof company say?
Question: Were these legs always pinned in the low position or could the pins have been missing allowing the legs to telescope up and down as the floater came down to low liquid level, possibly bringing liquid up through, then they were "found" and "fixed"?
It's hard to find the cause without being there, getting a complete operational history, talking to those on site, etc. I'm basically shooting in the dark hoping to hit something. I am likely way off base and it will turn out to be something completely different.
Good luck, keep your ears and eyes open and let us know what happens!
RE: oil and vapour come out from roof legs
Question: were the legs changed from low to high and position and back recently? If you pull a leg up, it may hold some liquid which might spill out.
no but even if this happen you a mouse hole in the bottom of the leg unless is blogged by sludge[/color] Question: please help me understand what items 21 on page 9 of 12 of the tank drawings set are used for ( spherical caps ) Question: what does the floating roof company say? we have not called them yet, and you can not trust them especially if there is a mistake in design of the tank. [pre]Question: Were these legs always pinned in the low position or could the pins have been missing allowing the legs to telescope up and down as the floater came down to low liquid level, possibly bringing liquid up through, then they were "found" and "fixed"? [color #EF2929]no one touch the legs for seven years
RE: oil and vapour come out from roof legs
RE: oil and vapour come out from roof legs
It doesn't look like it is a constant thing, but a one off event caused by air / vapour sliding around the top of the fluid / tank. I couldn't actually tell where your vents were or how many as the pdf drawings in red and yellow were very difficult to read.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: oil and vapour come out from roof legs
To increase the sleeve length, we would have to block the pin holes and make longer legs.
Mustafa - the drawings show mouse holes and spherical caps - you don't use both. Probably not a big deal, I was just curious.
There are rubber devices available that can be retrofitted on the legs to reduce emissions, these will also serve to minimize splash up through.
If this was a one-time event, clean it off, monitor operations and observe the deck for more oil.
RE: oil and vapour come out from roof legs
If the tank has been there 7 years and it's only happened once then it's not a systemic problem and might not happen again. It probably hasn't been cleaned or entered since going into service so who knows what the inside floor now looks like.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: oil and vapour come out from roof legs
I am really appreciated your reply.
IFRs,
Could you please send me more information regarding rubber devices
RE: oil and vapour come out from roof legs
I was thinking of thest http://ateco.com.tr/product/emission_control_devic... but from the original manufacturer, whose name eludes me right now.
RE: oil and vapour come out from roof legs
Thank for your kind reply.
in another case we have a single roof deck damaged completely because the pontoons get punctures although the tank is only 10 years old.
Any way, I have proposed the DOME ALUMINUM with AIFR because our product is light product "condensate". My company agree , but I have still some concerns below:-
1- Frangible roof is not possible . The frangible roof specified by API 650 is a valuable explosion
and over pressure protection, it is not known how the Aluminum domed roof will perform under
similar over pressure situations.
2-The quality of the Aluminum dome weather-tight design will vary by manufacturer.
3-Aluminum's lower resistance to turbulence (lower mass) shall be considered on tank stability
checking.
4-Modification to the existing facilities such like as structural , mechanical, piping, instrumentation &
controls, fire fighting , and fire and gas detection systems are a big concern in this retrofit project.
5-Galvanic corrosion which is the most common cause for Aluminum corrosion is a very real
concern in and near to coastal applications. Higher initial cost when compare to steel EFRT.
Please your help
RE: oil and vapour come out from roof legs
This is not an issue because the circulation vent area that is present with any internal floating roof is enough to provide emergency venting.
2-The quality of the Aluminum dome weather-tight design will vary by manufacturer.
This is an issue - buy a quality dome roof, not the least expensive one.
3-Aluminum's lower resistance to turbulence (lower mass) shall be considered on tank stability
checking.
This is true but tank stability can be checked mathematically. If the tank was stable as an open-top tank then adding a dome will not change that. If the tank currently has a steel cone roof, why change to a dome?
4-Modification to the existing facilities such like as structural , mechanical, piping, instrumentation &
controls, fire fighting , and fire and gas detection systems are a big concern in this retrofit project.
I think the only issue will be fire fighting - the aluminum IFR may require full-surface foam protection per NFPA or whatever code your live by in your country. Piping should not change, detection systems may change (but can usually be improved). You may find that you have more capacity because the AIFR can have a lower profile ( certain vendors and especially their seals ).
5-Galvanic corrosion which is the most common cause for Aluminum corrosion is a very real
concern in and near to coastal applications. Higher initial cost when compare to steel EFRT.
A marine environment can be an issue but galvanic should not because the steel tank to dome interface is via Teflon bearing pads under the dome structural connections ( or should be ). The internal floating roof should not care but you can get marine type alloys ( 52xx series ) from some vendors.
If you have the budget, you may want to consider upgrading to a more expensive aluminum floating roof for strength, emissions and safety reasons. At least one is made that is designed for the same load as a steel floating roof and several that are nearly as good.
Note: Among other things, I have worked with aluminum floating roof companies for 37 years and am not unbiased.
RE: oil and vapour come out from roof legs
Regarding point Nr.3 our existing tank is single deck floating external roof.
Point 4 we are following NFPA THE VENDOR WILL UPGRADE AS NFPA 11.
regarding the expensive aluminum floating roof for strength, we have receive an offer from CTS , Is this company okay with domes with AIFR (is there any other best company)??Moreover, could you send me any reference regarding ALLOY(52xx) for more information
I have PICTERS THE OFFER could you send me your mail address please to pass to you all things
RE: oil and vapour come out from roof legs
NFPA-11 allows only a limited few type of IFRs to have rim protection, all others require full-surface foam. You may already have full-surface protection, it is worth finding out.
For info on 5052 alloy, see these and many others:
http://www.metalsuppliersonline.com/Research/Prope...
http://en.wikipedia.org/wiki/Aluminium_alloy#Marin...
It would be better to go off-line to discus specific dome vendor's products.
There is only one aluminum internal floating roof that I know of that is designed for the same loads as a steel floating roof, there are some that are lower priced but still high quality and there are still more that are average quality and even lower priced. As is common throughout the world, to some extent you get what you pay for...
Click my name, there should be more information about me there.