application of pressure vessel in vacuum service 1

[142846]

hello every body
In the oil and gas company there is a pressure vessel with name plate that shows the specification as follow:
design pressure (MAWP): 10 barg
design temperature: 100 C
length: 8 meter
I.D = 2.5 meter
material; carbon steel
and there is not any information about vacuum design pressure.

we want to apply this pressure vessel in another system that all conditions (pressure,temp., flow rate ,...) are same as above but there is possibility of vacuum in some scenario.

Can we use this pressure vessel for new service?
in the other hand can we say that " because of this pressure vessel is suitable and resist for 10 barg then it is suitable for vacuum services".

thanks for any respond.

 

[saplanti]

Clearly the answer is NO. You need to provide a code calculation by considering the diameter, wall thicknesses, and circumferential stiffeners if it has any. By looking at the diameter only I would say it will not take full vacuum at all.

 

[pierreick]

Hi,
NO!
You need to have your vessel certified for vacuum .

Pierre

 

[LittleInch]

I also agree. Vacuum service is very different to positive pressure.

You cannot assume that just because the vessel is good for 10 barg it is good for -1 barg.

It might be but you need to do the design work and recertification is required.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[MJCronin]

I agree with the three comments above ....

Additionally, if the pressure vessel were to be "re-used" here in the US, there is an issue of re-certification by the National Board.

Here in the US, if you have an ASME pressure vessel and operate the vessel outside of the limits of design, then you must re-certify via the addition of an "NB" stamp. This is done by paying for a rerating by an organization qualified by the National Board

https://www.nationalboard.org/

We, of course, do not know where in the world that you are located .... I can only guess


MJCronin
Sr. Process Engineer

 

[142846]

thank you every body .
based on your comments, I understood the vacuum vessels has own calculations.
Just to better understanding the subject (me), imagine the design pressure was 100 barg instead of 10 barg (we don't have this vessel and just imagine if we had) , what was your answer in this case?
your answer is vessel should be certified for vacuum even for 100 barg?
I try to understand which parameter of the pressure vessel is more important than another when we encounter with vacuum systems? length or diameter or thickness or ...?

 

[bimr]

Don't believe that it was stated anywhere that this is a code stamped vessel. It looks like you are located outside the United States and you will have the follow whatever code is in place in your country or on your particular project.

You need to do the calculations to determine if the vessel will withstand vacuum. You also need to determine the age and condition of the vessel.

It is not uncommon for smaller diameter vessel to be capable of withstanding vacuum if the design pressures are elevated. For larger vessels, the steel is generally to thin.

 

[TiCl4]

142846,

The answers provided would not change based on the MAWP, be it 10 or 100 bar. As the MAWP increases, the greater the likelihood is that the vessel will have a full vacuum capability due to increasing metal thicknesses everywhere to hold the higher MAWP. However, without proper design calculations, it is impossible to know if the vessel would be able to withstand a full vacuum.

 

[LittleInch]

Let's be realistic here. 10 bar design on a 2.5m diam PV is going to be fairly decent. 100 bar even more so.

So the chance that the PV will fail a design check for vacuum with a MAWP of 10 bar is probably 10 to 15%
With a MAWP of 100 bar reduces to probably 3-5%.

But it is not ZERO chance.
And it won't be certified if you just do it anyway and then the vessel collapses or becomes damaged in some way.

There's no one parameter more important than the other. They all interact with each other

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[TiCl4]

LI,

Having gone through a PV design process for a 10' diameter vessel a few years ago, I can say that had we increased MAWP from 50 to 100 psig and increased head thickness by one size (from 3/8 to 1/2", if I remember correctly), the vessel would have passed calculations for F.V. without any stiffening rings. From this, I agree with your % assessment on holding vacuum, and that this vessel is more likely than not to pass checks for vacuum.

However, in many places in the world anyone can put a stamp with a MAWP value on anything without oversight. OP didn't state the design code or certification authority for that stamp, so there isn't any telling if our normal assumptions are correct.

 

[georgeverghese]

My guess is it may be ok for FV. But a guess is not good enough. In many countries, the plant owner may be prosecuted for operating a pressure vessel beyond its design limits. So you should get a professional registered pressure vessel design engineer to document the calcs for FV operation and have the calcs peer reviewed also. The mechanical static technical authority in this plant should then check and sign off authorisation to extend these operating limits. Then the plant owner representative should write out an application to your national pressure vessel board to get the registration info for this PV amended, with these supporting calcs and conclusions.
If the source of this new requirement is from plant process operators, a process safety audit should also be conducted to formalise this request and address any other attendant concerns.

 

[shvet]

Can we use this pressure vessel for new service?

It is a widespread practice to put a mid pressure vessel in vacuum service and find out that external pressure requires much more thickness of metal. You are not alone.

Each loss prevention book contains fotos and descriptions of cases this kind of. For example see:
- Kletz's What Went Wrong
- Sanders' Chemical Process Safety

Also there is a lot of videos how such pressure vessels collapse:

https://www.youtube.com/watch?v=0N17tEW_WEU

https://www.youtube.com/watch?v=VS6IckF1CM0

https://www.youtube.com/watch?v=0AUcTip7lv8

https://www.youtube.com/watch?v=y5VRww1Ypwk