Any oil or steel tank experts in here?

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12/12/2017 8:34 PM

working on a risk assessment paper for the Murphy oil spill

https://en.wikipedia.org/wiki/Murphy_Oil_USA_refinery_spill

The tank that ruptured had a storage capacity of 250k bbls, a diameter of 95 meters, est height of 16.6 meters, with a floating roof design.

Can any of you help estimate the mass of the steel tank?

I am having a hard time finding any material that suggests the mass of tanks this large.

For this assignment, we can estimate numbers for quantitative attributes (like mass of the tank) as long as they are "close"

Any of you out their have experience? millwrights, oil refinery folks, other engineers?

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12/12/2017 11:24 PM

Okay, I’m not the sharpest pencil in the drawer, are you asking the holding capacity, in weight, for this tank? From my Patch days, I recall a cubic metre holds 6.29 barrels, but you’d need the density of the oil, to figure the capacity for the tank. Heavy oil is up around 910-950 kgs per cube, light sweet is high 700’s, I believe. Been over 5 years since I hauled in the Bakken field.

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12/13/2017 4:17 AM

Tank and oil combined ? Oil weight should have a constant to figure the weight . Do a Google search on tubing calculator, there is plenty of info for figuring the weight of material based on the volume .

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12/13/2017 5:45 AM

scooter5002 wrote:

Okay, I’m not the sharpest pencil in the drawer, are you asking the holding capacity, in weight, for this tank? From my Patch days, I recall a cubic metre holds 6.29 barrels, but you’d need the density of the oil, to figure the capacity for the tank. Heavy oil is up around 910-950 kgs per cube, light sweet is high 700’s, I believe. Been over 5 years since I hauled in the Bakken field.

That is what I am going to calculate. One of the inputs for this calculation is the mass of the tank itself. I am having a difficult time even making an educated guess as to what the tank weighs empty.

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12/13/2017 6:40 AM
Edited Date/Time: 12/13/2017 6:42 AM

scooter5002 wrote:

Okay, I’m not the sharpest pencil in the drawer, are you asking the holding capacity, in weight, for this tank? From my Patch days, I recall a cubic metre holds 6.29 barrels, but you’d need the density of the oil, to figure the capacity for the tank. Heavy oil is up around 910-950 kgs per cube, light sweet is high 700’s, I believe. Been over 5 years since I hauled in the Bakken field.

mxtech1 wrote:

That is what I am going to calculate. One of the inputs for this calculation is the mass of the tank itself. I am having a difficult time even making an educated guess as to what the tank weighs empty.

The bottom ring is normally 3/4" to 1" thick with successive rings being thinner and with the top ring being 3/8" normally. The floor is usually 5/8" or 3/4". The floating roof would be 3/8" to 1/2" with an extra percentage added for the pontoons. Thickness times 40.8 will give you Lbs/ft2. Might be worth it to give someone at a tank building company like Horton/CBI a call for some rough numbers. https://www.cbi.com/Who-We-Serve/Industrial-Storage-Maintenance/Storage-Tanks-Vessels

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12/13/2017 6:58 AM

Foghorn wrote:

The bottom ring is normally 3/4" to 1" thick with successive rings being thinner and with the top ring being 3/8" normally. The floor is usually 5/8" or 3/4". The floating roof would be 3/8" to 1/2" with an extra percentage added for the pontoons. Thickness times 40.8 will give you Lbs/ft2. Might be worth it to give someone at a tank building company like Horton/CBI a call for some rough numbers. https://www.cbi.com/Who-We-Serve/Industrial-Storage-Maintenance/Storage-Tanks-Vessels

yes that's the rub...need to know the thickness of the steel in the tank before doing the math...

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12/13/2017 7:03 AM

Here's a guide for the wall thickness of the tank sides by height. Course 1 is always the bottom ring. Dimensions are in millimeters.Photo

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12/13/2017 7:06 AM

The thickness depends upon the standards that the tank is built to. Use API 620 or 650. The thickness is determined by a specific formula. Should be easy to look up.

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12/13/2017 7:18 AM

I did some calculations based on the information that has been posted. Thank you for your help.

My estimated tank weight from the calculation came out to about 655 tons.

Does this seem practical?

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12/13/2017 7:21 AM

mxtech1 wrote:

I did some calculations based on the information that has been posted. Thank you for your help.

My estimated tank weight from the calculation came out to about 655 tons.

Does this seem practical?

Without doing the math, it sounds like it's in the ball park for sure.

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12/13/2017 9:56 AM

Foghorn wrote:

Here's a guide for the wall thickness of the tank sides by height. Course 1 is always the bottom ring. Dimensions are in millimeters.Photo

Courses 1-6 are standard 96" plate dimensions. Why is 7-9 smaller?

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12/13/2017 10:36 AM

Foghorn wrote:

Here's a guide for the wall thickness of the tank sides by height. Course 1 is always the bottom ring. Dimensions are in millimeters.Photo

borg wrote:

Courses 1-6 are standard 96" plate dimensions. Why is 7-9 smaller?

Good question. My best guess without diving into design and code requirements is that in handling thinner plates, there is less possibility in damaging them during handling and placement based on structural stability.

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