Weight of Oil Storage Tank

[lovethecold]

I need to know the weight of an oil storage tank. The tank is 8.5 feet by 8.75 feet. It is insulated with 3" of foam, and aluminum sheeting. The tank has a 7000 gal capacity. It is my understanding that the dimensions include the insulation.

I would like this for my report and settlement calculations. At the moment I am assuming the tank weighs 15 kips. This is light considering the weight of the oil when fully loaded. But, I would like to at least be in the ballpark. The contractor we are working with doesn't have the requested information.

Thanks for your help.

- EIT Geotechnical Engineer. I am here hoping to help, and learn a little along the way.

 

[EdR]

Why don't you just compute the volume of steel times the density of steel (490 #/ft^3), the volume of the foam and sheeting times their densities, and the volume of the tank times the density of the liquid.......then add them together.....

Ed.R.

 

[ThePenguin]

From the outter dimensions less the thickness of the foam you should be able to find the area of the steel. However you will need the thickness of the various parts of the tank to get the volume and thus the weight of the steel as EdR proposed. If the tank is UL listed (UL-142 etc) the UL standard should contain the steel thickness, or atleast the minimum thickness for your size and type of tank.

Perhaps a little easier, you should be able to find the weight of similar tanks listed in manufacturers catalogs to get a ballpark idea. You mentioned that it is an oil tank, it may be possible that it is a double wall tank.

I assume since you only gave 2 dimensions, one is a diameter and the other is a height. The following is a link to some MFG data on single wall steel vertical above ground storage tanks (UL-142 listed). Also note they provide wall thicknesses for the head and shell.

http://www.highlandtank.com/LIT/HT_Aboveground_Vertical.pdf

If my assumptions are not correct

http://www.highlandtank.com

has numerous tanks and lists their weights, find a similar size and type of tank and you are in the ballpark.

Hope this helps.

 

[lovethecold]

EdR

I certainly could do as you suggest, accept how thick is the steel on such a tank, are there typically access doors or other steel inserts that I would have to account for, etc. Are these tanks typically 1/4 inch or 1/2 inch thick, or neither. I would guess these tanks are overdesigned, but to what extent. The contractor that we are working with is going mostly from memory, I am fortunate to have that info. I found some weight data for some smaller tanks (the largest less than half the volume). I doubled it, but was hoping to find some values that would confirm or give a closer value.

ThePenguin,

Thanks for the links. I would assume the tank is UL listed as they are for the DOT. As I understand it will be supported on end, on a stand 5.5' above ground. Based on the dimensions, I am assuming the tank is single wall.

I want to try to at least be in the ballpark when estimating the weight on this job. I would guess my tank is somewhere around 7 to 8 kips. I am trying to be closer in estimating the actual weight is the soil conditions are rather bad, even for a small tank like this and really shouldn't warrant recommending a deep foundation for this job. If this were for a house, then deep foundations may very well be recommended.

Thanks for the responses.

- EIT Geotechnical Engineer. I am here hoping to help, and learn a little along the way.

 

[rb1957]

you could ask a tank manufacturer roughly how heavy a 7000 gln tank would be ...

 

[EdR]

lovethecold:

I still think you would be better off computing the weight from each component part (and guessing what you don't know) than trying to guess an overall weight....Doing it by pieces will at least allow you a better estimate of where any errors might be....and will give a better idea of where and what might be important in the determination of the weight...i.e. if the weight of the contents is multiple times the weight of the steel tank then errors in the tank assumptions are not critical....etc..

Ed.R.

 

[BigH]

I think that you, and I am sorry, that you are going overboard. Just compute the weight by the steel as indicated above and forget the other things. Do you really think that in the weight of the tank, 5 to 10% difference in the weight of the tank will be significant for your settlement computations? How accurate do you think settlement computations are? If using consolidation theory, if you are within 25 to 35% you've had a good day, in sands it is not a heck of a lot different - and results by various methods differ. Keep the focus.