Storage Tank by PV Elite

[mhfitri]

Hi guys,

I`m designing a flat head storage by atmospheric pressure using PV Elite software and report the design data. However, i`ve been asked to include the foundation loading table, force and moment in all direction Fx, Fy Fz, Mx, My and Mz. I`ve been informed that PV Elite does not give the moment and force directly, and uses the worst load, Q. How should i solve this? Thanks in advanced

[FATHI]

Hope you can share with us the following:
Do you have a :ATMOSPHERIC, Vertical, cylindrical, flat bottom tank ??
Diameter ?
Height ?
corrosion allwance ?
Seismic ?
Type of roof : cone, floating roof ..?
Wind speed ?
Liquid density ?
material ? what is your Minimum mean day temperature to check material selection

But be aware that:
PVelite is for pressure vessels, heat exchangers, columns, drums according to ASME VIII , EN...
Storage tanks ( ATMOSPHERIC, Vertical, cylindrical, flat bottom ) are according to API 650 one of the software you could use is TANK (produced by PVelite owner).
You can also design a tank by hand calculation or bymaking your own excel sheets, probably you can find in this site some suitable excel spreadsheet for this purpose.
Tanks are limited in design internal pressure (very low not higher than atmospheric).

Tank are thin walled structure the wind and seismic are somewhat different to conduct than Vessels, further you have to select the thickness of the annular plate and design the roof as a structure when it is not self supported (within the limitation given in API 650).Checking for vacuum and adding stiffeners is also a special feature for tank (API has it is own rules). Also API 650 has other rules about testing and radiography ...

For your case calculate the empty case, the hydrotest case , the seismic case and check if you need anchor bolts or not. Give the loads ( H, V, Overturning ) to the civil for sizing the structure, estimating the settlement, design foundation if needed.

Do you have a :ATMOSPHERIC, Vertical, cylindrical, flat bottom tank ??
Diameter ?
Height ?
Type of roof : cone, floating roof ..?
Wind speed ?
Liquid density ?
material ? what is your Minimum mean day temperature to check material selection

[mhfitri]

Hi FATHI,

I`m designing an atmospheric diesel storage tank according to the ASME VIII DIV I,

Wind Speed = 117 km/hr
CA = 1.5
Seismic Load Reduction Factor = 0.7
Importance Factor = 1.15

Wind and Seismic is as per ASCE7-2010.
Should i wish to manual calculate the foundation load of the horizontal tank, wish appendix should i refer to?

[FATHI]

Load on foundation are due to:
1/- Tank empty load, including all structure ( roof, rails, fittings,etc)
2/- Same as 1/ above but tank full of liquid = operating case
3/- Same as 1/- above but tank full of water = hydrotest case, this will give probably the highest uniform bearing load
4/- Case 2 + wind load
5/- Case 2 + seismic load
Case 3 , 4 and 5 have a vertical , a horizontal (shear) loads and also an overturning moment

case 4 and 5 will give you the highest bolting load ( if anchor bolts or strips are used)

Civil department needs to design foundation + check bearing pressure versus their allowable , and ensure that foundation settlement is acceptable, remember than most of the settlement will occur during hydrotest.

you have not suppied Tank daimeter , height, liquid density, type of roof, materials to enable me or other colleagues on this help you.
I believe you can find on this forum some excel spreadsheets to help you to calculate all the loads on the foundation.

[mhfitri]

Hi FATHI,

Diameter : 2400
Height (Include Saddle) : 2750
Liquid : Diesel
Flat head horizontal tank
Material : SA-36

it seem that you know your way around PV Elite. How do we get the foundation load of force and moment at the anchor?

[FATHI]

There is a small semantic issue here..a problem of terminology.

Although this is called a tank on a PID or on a process datasheet this is not a tank (as per API 650), Because it is not vertical , not flat bottom etc..
because of the very low internal pressure , this is not a pressure vessel ( as per ASME VIII)

Such non-ASME vessel would be designed as per good practice for instance according UL 142
Standard for Steel Aboveground Tanks for Flammable and Combustible Liquids

this is not a big issue providing you ensure and check:
1- Do you have a have a vacuum or partial vacuum case ? check with your process people please.
2- when you add saddles ( two) underneath your tank make sure that one is sliding to allow one side of this tank to expand freely and avoid thermal loads
3- make sure that you use elliptical heads , because flat heads for such diameters will get thick very quickly.

you can use PVelite and enter all your infos and get the weight and the loads

all in all you will get small overturning moments and only the tank + its weight will count really , I suggest you enter 1 bar = 0.1 N/mm2 as internal pressure , you enter your vacumm if any , seismic , wind ..you will get the weight, you can calculate with a density of 1 , select a saddle from PV elite data base
I expect you to have a thickness of about 5 to 6 mm including corrosion allowance and try to avoid flat heads (also hard to weld)

good luck
And salam to all

[mhfitri]

Hi FATHI,

Thank you for your information time and patient, i learn a lot from this. One last thing, what is the different between Pv Elite and Code Calc? I usually use pv elite and try to use Code Calc yesterday and came with this. I put the 121kpa for internal and 101kpa for external pressure and PV elite gives thickness of 11.5mm while Code Calc does not calculate the external pressure and only gives min req 3mm thk due to internal pressure of the cylindrical shell. Why did Code Calc did not take external pressure into consideration of the plate thickness?

I went through the design report, the data for the Force and Moment at the anchor does not shows as Fx, Fy, Fz of each bolting/saddle. Does it shows in another form?

[FATHI]

1-PVelite is for a vessels as a whole. It contains already Codecalc.
Codecalc alone is for component design ( a head alone, a shell alone,flange alone ..) it can also not calculate wind or seimic.


2-A vacuum give quickly a thick vessel shell, unless you use stiffer rings to make shell a bit stiff ( rigid).

3-It seems that your external pressure is a bit high, why don' t you talk to your process people a use a more realistic value than you will get lower thicknesses.
4-For your case the load of the vessel= horizontal tank is governing this means the reaction of the saddles and their disposition will give some moment onto the vessel, but no worries PVelite will calculate that for you

5-Flat heads are thick, why don't you use elliptical heads: cheaper and easy to weld a also can get more external pressure. Flat heads are a bad idea.

6-Easier for you to calculate wind loads ( forces and moment) on anchor bolts/foundation. You have the whole procedure here (=Vessel Design Manual / By Moses) , just follow the procedure a do calcs by hand till you understand them, at the end use excel or similar.
here is the link for dowloding this manual:

[link Point to another website Only the registered members can access]
PVelite uses also this book and it refers to it in his calcs
7- for your case , DO NOT forget to leave one saddle free to expand/ move
6/-Use a wear plate between saddle and vessel , this a good practice, also remove sharp edges of wear plates.


talk care

greetings to all people on this forum

[mhfitri]

Hi FATHI,

I cannot thank you enough, you`re really a big help to me. Thank you

[FATHI]

mhfitri,

..no thanks,
always ready to help.
I believe this is the spirit of this forum.

[marian_g]

Unless you use the "tank" as a submarine able to submerse 10 meters in water, you don't need 121kpa for internal pressure and 101kpa for external pressure.
I mean in case your 101 kPa means atmospheric pressure you don't need to consider it as external. When you input something as external pressure, it means that there is a scenario in which that external pressure acts alone.
For your case it is likely that 101 kPa external is coincident with 121 kPa inside tank, or- in case tank is empty- 101 kPa external is coincident with 101 kPa internal.
Am I right making such assumption or really you have a case in which you have a full vacuum inside, which is equivalent with 101 kPa external and 0 kPa internal?

[mhfitri]

Dear marian,

Thus by your wisdom, when designing an atmospheric tank, what is the appropriate internal and external pressure for the tank? I was made to understand that the external pressure should be 1 atm and internal pressure is 1 atm + liquid level when designing the tank. The storage tank content is expected to have free flow at the outlets and drain without using any pump, and maybe expected to have a vacuum when the liquid level is low.