Hello everybody,

Can anyone explain me how to consider "steam out condition" in case of PVElite?

Given Data for the vessel is as follows,

Internal Pressure = 4 Kgf/cm2
Internal Design Temp = 120 deg C
External Pressure = FV (1.055 Kgf/cm2)
External Design Temp = 100 deg C

One additional note given for "steam out condition" is 0.5 Kgf/cm2 @ 230 deg C.

At first i have designed my vessel for Internal & External Design conditions. But now i have to design for "steam out condition", so how to consider it?
I mean what is inside & outside, pressure & temp to enter in PVElite for "Steam out condition".

Makrand.

Hi Makrand,

For steam out condition you have to apply steam out pressure 0.5 kgf/cm2 as external design pressure for vessel design. However, Internal pressure remains same as 4 kgf/cm2.

For your vessel design, you may have to consider the worst case of external design pressure which will include steam out condition also i.e. 1.055 kgf/cm2 (FV) + 0.5 kgf/cm2(Steam out condition).



S.K.

Mak,

I tend to disagree with the above advice, as the steam out condition is not necessarily a design condition, but a design verification condition. In no case, the steam out condition would refer to external pressure, unless the Client specification clearly mentioned the partial or full vacuum condition as a consequence of steam out process (in case of blocked vents, the condensing steam may generate a vacuum in the vessel). In your case the the external pressure has been nominated FV, but the internal pressure of 0.5 kgf/cm2 (please note that the steam is applied inside the vessels for clean-out purposes) is less than the design pressure, hence no effect on the vessel components. However the steam out temperature may affect other components, say during an earthquake the excess temperature could affect adversely the support design...So in the loading conditions, you may include the 230 deg C for the supports check, with 0.5 barg internal pressure, instead of the design or operating pressure.

cheers,
gr2vessels

Thanks Mr. S.K.,

But can you please tell me what inside & outside temperature would be?