Storage Tank by PV Elite

[marian_g]

As numbers, considering absolute pressure in and out appears to be OK, but when you use a software like PV elite, it is understood that you have two scenarios- one with external pressure alone, one with internal pressure alone.

In fact a pressure vessel is essentially designed to the relative internal pressure. In some cases, you must consider the external pressure which can be created in three ways:

-From a vacuum inside a vessel and atmospheric pressure outside (two simple examples of sources of vacuum – unloading a vessel or a tank that is not adequately vented – or – cooling down a vessel filled with steam that condenses to water);
-From a pressure outside a vessel greater than atmospheric (typically from some types of jacket or a surrounding vessel)
-From a combination of the first two – vacuum inside + pressure greater than atmospheric outside.


To answer specifically to your question, you may design your tank according to EN 12285-2:2005 (Workshop fabricated steel tanks - Part 2: Horizontal cylindrical single skin and double skin tanks for the aboveground storage of flammable and non-flammable water polluting liquids) to the limits of this standard, or any other specification having this subject.

[mhfitri]

Dear marian,

Thank you for being patient with me.
By the way, the storage tank that i`m designing (according to ASME VIII) having a vent and no relief valve. There might be vacuum happened, so we might have to consider partial vacuum or full vacuum.
I tried with full vacuum condition, where internal pressure is 0 and external is 1 atm, still the trext boost up to 11.5mm. Am i correct having 1 atm during full vacuum or there is a formula to calculate the external pressure of full/partial vacuum condition?

[marian_g]

Normally, if the vessel is to be 'U' stamped, and it is subjected to external pressure, that external pressure must be set to a minimum of 15 psig (103.42 kPa) or FV. It is true also that by UG-116 and 119, is required to specify the maximum allowable external working pressure (only when specified as a design condition), hence the PV can be dimensioned also to other conditions than FV.
You are not under U stamp ASME VIII Div 1 condition, you don't need to follow it.
In case you are interested, you can search the subject trough PVElite/ Coade forum- in fact you just posted there your question.
See for expample

[link Point to another website Only the registered members can access]

For your case, be sure that the vents are generously dimensioned as the air inlet flow rate can far exceed the flowrate when drain the tank and never your tank will be subject to vacuum.

[mhfitri]

Dear marian,

Thank you for your help. Really appreciate it

[marian_g]

If I were you I would consider preliminary the minimum nominal thickness from EN mentioned adding corrosion allowance. EN gives you some numbers in between of those calculated by you. Be aware that there are differences when tank has welded saddles or loose-fitting type. I would use a rough hand calculation or PVElite just to confirm wind and seismic scenarios/ saddles load and tank thickness.
Some things do not need to be deeply calculated, that's the real engineering.

[rosenice]

Dear all

Using compress we can easily convert files into xml format which can be opened in other softwares.I am using pvelite 2016 v18 SP1 . I want to convert my pvelite file into xml format. Kindly give me way out.Actually I want to open my pvelite model into AMPreva by technosoft which can import xml files.Looking for your expert response.Sincere regards,